PIC18F4520TI/MLQTP [MICROCHIP]
28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology; 28 /40/ 44引脚增强型闪存微控制器与10位A / D和纳瓦技术
| 型号： | PIC18F4520TI/MLQTP |
| 厂家： | 
MICROCHIP |
| 描述： | 28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology |
| 文件： | 总390页 (文件大小：7139K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PIC18F2420/2520/4420/4520
Data Sheet
28/40/44-Pin
Enhanced Flash Microcontrollers
with 10-Bit A/D and nanoWatt Technology
2004 Microchip Technology Inc.
Preliminary
DS39631A
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical
components in life support systems is not authorized except
with express written approval by Microchip. No licenses are
conveyed, implicitly or otherwise, under any intellectual
property rights.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, microID, MPLAB, PIC, PICmicro, PICSTART,
PRO MATE, PowerSmart, rfPIC, and SmartShunt are
registered trademarks of Microchip Technology Incorporated
in the U.S.A. and other countries.
AmpLab, FilterLab, MXDEV, MXLAB, PICMASTER, SEEVAL,
SmartSensor and The Embedded Control Solutions Company
are registered trademarks of Microchip Technology
Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, dsPICDEM,
dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR,
FanSense, FlexROM, fuzzyLAB, In-Circuit Serial
Programming, ICSP, ICEPIC, Migratable Memory, MPASM,
MPLIB, MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net,
PICLAB, PICtail, PowerCal, PowerInfo, PowerMate,
PowerTool, rfLAB, rfPICDEM, Select Mode, Smart Serial,
SmartTel and Total Endurance are trademarks of Microchip
Technology Incorporated in the U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2004, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received ISO/TS-16949:2002 quality system certification for
its worldwide headquarters, design and wafer fabrication facilities in
Chandler and Tempe, Arizona and Mountain View, California in
October 2003. The Company’s quality system processes and
procedures are for its PICmicro® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
DS39631A-page ii
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
28/40/44-Pin Enhanced Flash Microcontrollers with
10-Bit A/D and nanoWatt Technology
Power Managed Modes:
Flexible Oscillator Structure:
• Run: CPU on, peripherals on
• Four Crystal modes, up to 40 MHz
• Idle: CPU off, peripherals on
• 4X Phase Lock Loop (available for crystal and
internal oscillators)
• Two External RC modes, up to 4 MHz
• Two External Clock modes, up to 40 MHz
• Internal oscillator block:
- 8 user selectable frequencies, from 31 kHz to 8 MHz
- Provides a complete range of clock speeds
from 31 kHz to 32 MHz when used with PLL
- User tunable to compensate for frequency drift
• Secondary oscillator using Timer1 @ 32 kHz
• Fail-Safe Clock Monitor:
• Sleep: CPU off, peripherals off
• Idle mode currents down to 5.8 µA typical
• Sleep mode current down to 0.1 µA typical
• Timer1 Oscillator: 1.8 µA, 32 kHz, 2V
• Watchdog Timer: 2.1 µA
• Two-Speed Oscillator Start-up
Peripheral Highlights:
• High-current sink/source 25 mA/25 mA
• Three programmable external interrupts
• Four input change interrupts
- Allows for safe shutdown if peripheral clock stops
• Up to 2 Capture/Compare/PWM (CCP) modules,
one with Auto-Shutdown (28-pin devices)
• Enhanced Capture/Compare/PWM (ECCP)
module (40/44-pin devices only):
Special Microcontroller Features:
• C compiler optimized architecture:
- Optional extended instruction set designed to
optimize re-entrant code
- One, two or four PWM outputs
• 100,000 erase/write cycle Enhanced Flash
program memory typical
- Selectable polarity
- Programmable dead time
• 1,000,000 erase/write cycle Data EEPROM
memory typical
• Flash/Data EEPROM Retention: 100 years typical
• Self-programmable under software control
• Priority levels for interrupts
• 8 x 8 Single-Cycle Hardware Multiplier
• Extended Watchdog Timer (WDT):
- Programmable period from 4 ms to 131s
• Single-supply 5V In-Circuit Serial
Programming™ (ICSP™) via two pins
• In-Circuit Debug (ICD) via two pins
• Wide operating voltage range: 2.0V to 5.5V
• Programmable 16-level High/Low-Voltage
Detection (HLVD) module:
- Auto-Shutdown and Auto-Restart
• Master Synchronous Serial Port (MSSP) module
supporting 3-wire SPI™ (all 4 modes) and I2C™
Master and Slave Modes
• Enhanced Addressable USART module:
- Supports RS-485, RS-232 and LIN 1.2
- RS-232 operation using internal oscillator
block (no external crystal required)
- Auto-Wake-up on Start bit
- Auto-Baud Detect
• 10-bit, up to 13-channel Analog-to-Digital
Converter module (A/D):
- Auto-acquisition capability
- Conversion available during Sleep
• Dual analog comparators with input multiplexing)
- Supports interrupt on High/Low-Voltage
Detection
• Programmable Brown-out Reset (BOR
- With software enable option
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 1
PIC18F2420/2520/4420/4520
-
Program Memory
Data Memory
MSSP
CCP/
ECCP
(PWM)
10-bit
A/D (ch)
Timers
8/16-bit
Device
I/O
Comp.
Flash # Single-Word SRAM EEPROM
(bytes) Instructions (bytes) (bytes)
Master
SPI
2
I C
PIC18F2420
PIC18F2520
PIC18F4420
PIC18F4520
16K
32K
16K
32K
8192
16384
8192
768
1536
768
256
256
256
256
25
25
36
36
10
10
13
13
2/0
2/0
1/1
1/1
Y
Y
Y
Y
Y
Y
Y
Y
1
1
1
1
2
2
2
2
1/3
1/3
1/3
1/3
16384
1536
DS39631A-page 2
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
Pin Diagrams
28-pin PDIP, SOIC
1
2
3
4
5
6
7
8
9
28
27
26
25
24
23
22
21
20
19
18
17
16
15
RB7/KBI3/PGD
RB6//KBI2/PGC
RB5/KBI1/PGM
RB4/KBI0/AN11
RB3/AN9/CCP2(1)
RB2/INT2/AN8
RB1/INT1/AN10
MCLR/VPP/RE3
RA0/AN0
RA1/AN1
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
VSS
RB0/INT0/FLT0/AN12
VDD
OSC1/CLKI/RA7
OSC2/CLKO/RA6
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1
VSS
10
11
RC7/RX/DT
RC6/TX/CK
RC5/SDO
RC4/SDI/SDA
12
13
14
RC3/SCK/SCL
40-pin PDIP
MCLR/VPP/RE3
RA0/AN0
1
2
3
4
5
6
7
8
9
RB7/KBI3/PGD
RB6/KBI2/PGC
RB5/KBI1/PGM
RB4/KBI0/AN11
RB3/AN9/CCP2(1)
RB2/INT2/AN8
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
RA1/AN1
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
RE0/RD/AN5
RB1/INT1/AN10
RB0/INT0/FLT0/AN12
VDD
VSS
RE1/WR/AN6
RE2/CS/AN7
10
VDD
VSS
11
12
13
14
15
16
17
18
19
20
RD7/PSP7/P1D
RD6/PSP6/P1C
RD5/PSP5/P1B
RD4/PSP4
RC7/RX/DT
RC6/TX/CK
RC5/SDO
OSC1/CLKI/RA7
OSC2/CLKO/RA6
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1/P1A
RC3/SCK/SCL
RD0/PSP0
RC4/SDI/SDA
RD3/PSP3
RD1/PSP1
RD2/PSP2
28-pin QFN
28272625242322
RB3/AN9/CCP2(1)
RB2/INT2/AN8
RB1/INT1/AN10
RB0/INT0/FLT0/AN12
VDD
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
VSS
1
2
3
4
5
6
7
21
20
19
18
17
16
15
PIC18F2420
PIC18F2520
OSC1/CLKI/RA7
OSC2/CLKO/RA6
VSS
RC7/RX/DT
8
9 1011 121314
Note 1: RB3 is the alternate pin for CCP2 multiplexing.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 3
PIC18F2420/2520/4420/4520
Pin Diagrams (Cont.’d)
44-pin TQFP
NC
33
32
31
30
29
28
27
26
25
24
23
RC7/RX/DT
RD4/PSP4
RD5/PSP5/P1B
RD6/PSP6/P1C
RD7/PSP7/P1D
VSS
1
2
3
4
5
6
7
8
9
RC0/T1OSO/T13CKI
OSC2/CLKO/RA6
OSC1/CLKI/RA7
VSS
PIC18F4420
PIC18F4520
VDD
RE2/CS/AN7
RE1/WR/AN6
RE0/RD/AN5
RA5/AN4/SS/HLVDIN/C2OUT
RA4/T0CKI/C1OUT
VDD
RB0/INT0/FLT0/AN12
RB1/INT1/AN10
RB2/INT2/AN8
RB3/AN9/CCP2(1)
10
11
44-pin QFN
RC7/RX/DT
RD4/PSP4
RD5/PSP5/P1B
RD6/PSP6/P1C
RD7/PSP7/P1D
VSS
OSC2/CLKO/RA6
OSC1/CLKI/RA7
VSS
VSS
VDD
VDD
RE2/CS/AN7
RE1/WR/AN6
RE0/RD/AN5
RA5/AN4/SS/HLVDIN/C2OUT
RA4/T0CKI/C1OUT
33
1
2
3
4
5
6
7
8
9
32
31
30
29
28
27
26
PIC18F4420
PIC18F4520
VDD
VDD
RB0/INT0/FLT0/AN12
RB1/INT1/AN10
RB2/INT2/AN8
25
24
23
10
11
Note 1: RB3 is the alternate pin for CCP2 multiplexing.
DS39631A-page 4
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
Table of Contents
1.0 Device Overview .......................................................................................................................................................................... 7
2.0 Oscillator Configurations ............................................................................................................................................................ 23
3.0 Power Managed Modes ............................................................................................................................................................. 33
4.0 Reset.......................................................................................................................................................................................... 41
5.0 Memory Organization................................................................................................................................................................. 53
6.0 Flash Program Memory.............................................................................................................................................................. 73
7.0 Data EEPROM Memory ............................................................................................................................................................. 83
8.0 8 x 8 Hardware Multiplier............................................................................................................................................................ 89
9.0 Interrupts .................................................................................................................................................................................... 91
10.0 I/O Ports ................................................................................................................................................................................... 105
11.0 Timer0 Module ......................................................................................................................................................................... 123
12.0 Timer1 Module ......................................................................................................................................................................... 127
13.0 Timer2 Module ......................................................................................................................................................................... 133
14.0 Timer3 Module ......................................................................................................................................................................... 135
15.0 Capture/Compare/Pwm (CCP) Modules .................................................................................................................................. 139
16.0 Enhanced Capture/Compare/PWM (ECCP) Module................................................................................................................ 147
17.0 Master Synchronous Serial Port (MSSP) Module .................................................................................................................... 161
18.0 Enhanced Universal Synchronous Receiver Transmitter (EUSART)....................................................................................... 201
19.0 10-Bit Analog-to-Digital Converter (A/D) Module ..................................................................................................................... 223
20.0 Comparator Module.................................................................................................................................................................. 233
21.0 Comparator Voltage Reference Module................................................................................................................................... 239
22.0 High/Low-Voltage Detect (HLVD)............................................................................................................................................. 243
23.0 Special Features of the CPU.................................................................................................................................................... 249
24.0 Instruction Set Summary.......................................................................................................................................................... 267
25.0 Development Support............................................................................................................................................................... 317
26.0 Electrical Characteristics.......................................................................................................................................................... 323
27.0 DC and AC Characteristics Graphs and Tables....................................................................................................................... 361
28.0 Packaging Information.............................................................................................................................................................. 363
Appendix A: Revision History............................................................................................................................................................. 371
Appendix B: Device Differences ........................................................................................................................................................ 371
Appendix C: Conversion Considerations ........................................................................................................................................... 372
Appendix D: Migration from Baseline to Enhanced Devices.............................................................................................................. 372
Appendix E: Migration from Mid-Range to Enhanced Devices.......................................................................................................... 373
Appendix F: Migration from High-End to Enhanced Devices............................................................................................................. 373
Index .................................................................................................................................................................................................. 375
On-Line Support................................................................................................................................................................................. 385
Systems Information and Upgrade Hot Line ...................................................................................................................................... 385
Reader Response.............................................................................................................................................................................. 386
PIC18F2420/2520/4420/4520 Product Identification System ............................................................................................................ 387
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 5
PIC18F2420/2520/4420/4520
TO OUR VALUED CUSTOMERS
It is our intention to provide our valued customers with the best documentation possible to ensure successful use of your Microchip
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We welcome your feedback.
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The last character of the literature number is the version number, (e.g., DS30000A is version A of document DS30000).
Errata
An errata sheet, describing minor operational differences from the data sheet and recommended workarounds, may exist for current
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To determine if an errata sheet exists for a particular device, please check with one of the following:
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DS39631A-page 6
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
1.1.2
MULTIPLE OSCILLATOR OPTIONS
AND FEATURES
1.0
DEVICE OVERVIEW
This document contains device specific information for
the following devices:
All of the devices in the PIC18F2420/2520/4420/4520
family offer ten different oscillator options, allowing
users a wide range of choices in developing application
hardware. These include:
• PIC18F2420
• PIC18F2520
• PIC18F4420
• PIC18F4520
• PIC18LF2420
• PIC18LF2520
• PIC18LF4420
• PIC18LF4520
• Four Crystal modes, using crystals or ceramic
resonators
• Two External Clock modes, offering the option of
using two pins (oscillator input and a divide-by-4
clock output) or one pin (oscillator input, with the
second pin reassigned as general I/O)
This family offers the advantages of all PIC18 micro-
controllers – namely, high computational performance
at an economical price – with the addition of high-
endurance, Enhanced Flash program memory. On top
of these features, the PIC18F2420/2520/4420/4520
family introduces design enhancements that make
these microcontrollers a logical choice for many high-
performance, power sensitive applications.
• Two External RC Oscillator modes with the same
pin options as the External Clock modes
• An internal oscillator block which provides an
8 MHz clock and an INTRC source (approxi-
mately 31 kHz), as well as a range of 6 user
selectable clock frequencies, between 125 kHz to
4 MHz, for a total of 8 clock frequencies. This
option frees the two oscillator pins for use as
additional general purpose I/O.
1.1
New Core Features
1.1.1
nanoWatt TECHNOLOGY
All of the devices in the PIC18F2420/2520/4420/4520
family incorporate a range of features that can signifi-
cantly reduce power consumption during operation.
Key items include:
• A Phase Lock Loop (PLL) frequency multiplier,
available to both the high-speed crystal and inter-
nal oscillator modes, which allows clock speeds of
up to 40 MHz. Used with the internal oscillator, the
PLL gives users a complete selection of clock
speeds, from 31 kHz to 32 MHz – all without using
an external crystal or clock circuit.
• Alternate Run Modes: By clocking the controller
from the Timer1 source or the internal oscillator
block, power consumption during code execution
can be reduced by as much as 90%.
Besides its availability as a clock source, the internal
oscillator block provides a stable reference source that
gives the family additional features for robust
operation:
• Multiple Idle Modes: The controller can also run
with its CPU core disabled but the peripherals still
active. In these states, power consumption can be
reduced even further, to as little as 4% of normal
operation requirements.
• Fail-Safe Clock Monitor: This option constantly
monitors the main clock source against a refer-
ence signal provided by the internal oscillator. If a
clock failure occurs, the controller is switched to
the internal oscillator block, allowing for continued
low-speed operation or a safe application
shutdown.
• On-the-fly Mode Switching: The power
managed modes are invoked by user code during
operation, allowing the user to incorporate power-
saving ideas into their application’s software
design.
• Low Consumption in Key Modules: The
power requirements for both Timer1 and the
Watchdog Timer are minimized. See
Section 26.0 “Electrical Characteristics”
for values.
• Two-Speed Start-up: This option allows the
internal oscillator to serve as the clock source
from Power-on Reset, or wake-up from Sleep
mode, until the primary clock source is available.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 7
PIC18F2420/2520/4420/4520
1.2
Other Special Features
1.3
Details on Individual Family
Members
• Memory Endurance: The Enhanced Flash cells
for both program memory and data EEPROM are
rated to last for many thousands of erase/write
cycles – up to 100,000 for program memory and
1,000,000 for EEPROM. Data retention without
refresh is conservatively estimated to be greater
than 40 years.
Devices in the PIC18F2420/2520/4420/4520 family are
available in 28-pin and 40/44-pin packages. Block
diagrams for the two groups are shown in Figure 1-1
and Figure 1-2.
The devices are differentiated from each other in five
ways:
• Self-programmability: These devices can write
to their own program memory spaces under inter-
nal software control. By using a bootloader routine
located in the protected Boot Block at the top of
program memory, it becomes possible to create
an application that can update itself in the field.
1. Flash program memory (16 Kbytes for
PIC18F2420/4420 devices and 32 Kbytes for
PIC18F2520/4520).
2. A/D channels (10 for 28-pin devices, 13 for
40/44-pin devices).
3. I/O ports (3 bidirectional ports on 28-pin devices,
5 bidirectional ports on 40/44-pin devices).
• Extended Instruction Set: The PIC18F2420/
2520/4420/4520 family introduces an optional
extension to the PIC18 instruction set, which adds
8 new instructions and an Indexed Addressing
mode. This extension, enabled as a device con-
figuration option, has been specifically designed
to optimize re-entrant application code originally
developed in high-level languages, such as C.
4. CCP and Enhanced CCP implementation
(28-pin devices have 2 standard CCP mod-
ules, 40/44-pin devices have one standard CCP
module and one ECCP module).
5. Parallel Slave Port (present only on 40/44-pin
devices).
• Enhanced CCP module: In PWM mode, this
module provides 1, 2 or 4 modulated outputs for
controlling half-bridge and full-bridge drivers.
Other features include Auto-Shutdown, for dis-
abling PWM outputs on interrupt or other select
conditions and Auto-Restart, to reactivate outputs
once the condition has cleared.
All other features for devices in this family are identical.
These are summarized in Table 1-1.
The pinouts for all devices are listed in Table 1-2 and
Table 1-3.
Like all Microchip PIC18 devices, members of the
PIC18F2420/2520/4420/4520 family are available as
both standard and low-voltage devices. Standard
devices with Enhanced Flash memory, designated with
an “F” in the part number (such as PIC18F2420),
accommodate an operating VDD range of 4.2V to 5.5V.
Low-voltage parts, designated by “LF” (such as
PIC18LF2420), function over an extended VDD range
of 2.0V to 5.5V.
• Enhanced Addressable USART: This serial
communication module is capable of standard
RS-232 operation and provides support for the LIN
bus protocol. Other enhancements include
automatic baud rate detection and a 16-bit Baud
Rate Generator for improved resolution. When the
microcontroller is using the internal oscillator
block, the USART provides stable operation for
applications that talk to the outside world without
using an external crystal (or its accompanying
power requirement).
• 10-bit A/D Converter: This module incorporates
programmable acquisition time, allowing for a
channel to be selected and a conversion to be
initiated without waiting for a sampling period and
thus, reduce code overhead.
• Extended Watchdog Timer (WDT): This
enhanced version incorporates a 16-bit prescaler,
allowing an extended time-out range that is stable
across operating voltage and temperature. See
Section 26.0 “Electrical Characteristics” for
time-out periods.
DS39631A-page 8
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-1:
DEVICE FEATURES
Features
PIC18F2420
PIC18F2520
PIC18F4420
PIC18F4520
Operating Frequency
DC – 40 MHz
16384
DC – 40 MHz
32768
DC – 40 MHz
16384
DC – 40 MHz
32768
Program Memory (Bytes)
Program Memory
(Instructions)
8192
16384
8192
16384
Data Memory (Bytes)
Data EEPROM Memory (Bytes)
Interrupt Sources
768
1536
768
1536
256
256
256
256
19
19
20
20
I/O Ports
Ports A, B, C, (E)
Ports A, B, C, (E)
Ports A, B, C, D, E
Ports A, B, C, D, E
Timers
4
2
0
4
2
0
4
1
1
4
1
1
Capture/Compare/PWM Modules
Enhanced
Capture/Compare/PWM Modules
Serial Communications
MSSP,
MSSP,
MSSP,
MSSP,
Enhanced USART
Enhanced USART
Enhanced USART
Enhanced USART
Parallel Communications (PSP)
10-bit Analog-to-Digital Module
Resets (and Delays)
No
No
Yes
Yes
10 Input Channels
10 Input Channels
13 Input Channels
13 Input Channels
POR, BOR,
POR, BOR,
POR, BOR,
POR, BOR,
RESETInstruction,
Stack Full, Stack
RESETInstruction,
Stack Full, Stack
RESETInstruction,
Stack Full, Stack
RESETInstruction,
Stack Full, Stack
Underflow (PWRT, OST), Underflow (PWRT, OST), Underflow (PWRT, OST), Underflow (PWRT, OST),
MCLR (optional), WDT
MCLR (optional), WDT
MCLR (optional), WDT
MCLR (optional), WDT
Programmable
Yes
Yes
Yes
Yes
High/Low-Voltage Detect
Programmable Brown-out Reset
Instruction Set
Yes
Yes
Yes
Yes
75 Instructions;
83 with Extended
75 Instructions;
83 with Extended
75 Instructions;
83 with Extended
75 Instructions;
83 with Extended
Instruction Set enabled
Instruction Set enabled
Instruction Set enabled
Instruction Set enabled
Packages
28-pin PDIP
28-pin SOIC
28-pin QFN
28-pin PDIP
28-pin SOIC
28-pin QFN
40-pin PDIP
44-pin QFN
44-pin TQFP
40-pin PDIP
44-pin QFN
44-pin TQFP
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 9
PIC18F2420/2520/4420/4520
FIGURE 1-1:
PIC18F2420/2520 (28-PIN) BLOCK DIAGRAM
Data Bus<8>
Table Pointer<21>
Data Latch
PORTA
8
8
inc/dec logic
21
RA0/AN0
RA1/AN1
Data Memory
( 3.9 Kbytes )
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
OSC2/CLKO(3)/RA6
OSC1/CLKI(3)/RA7
PCLATH
PCLATU
Address Latch
20
PCU PCH PCL
Program Counter
12
Data Address<12>
31 Level Stack
STKPTR
4
BSR
12
FSR0
FSR1
FSR2
4
Address Latch
Access
Bank
Program Memory
(16/32 Kbytes)
12
Data Latch
PORTB
RB0/INT0/FLT0/AN12
RB1/INT1/AN10
RB2/INT2/AN8
inc/dec
logic
8
Table Latch
RB3/AN9/CCP2(1)
RB4/KBI0/AN11
RB5/KBI1/PGM
RB6/KBI2/PGC
RB7/KBI3/PGD
Address
Decode
ROM Latch
IR
Instruction Bus <16>
8
State machine
control signals
Instruction
Decode and
Control
PRODH PRODL
8 x 8 Multiply
PORTC
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1
3
8
W
BITOP
8
RC3/SCK/SCL
RC4/SDI/SDA
RC5/SDO
8
8
Internal
Oscillator
Block
OSC1(3)
OSC2(3)
T1OSI
Power-up
Timer
RC6/TX/CK
RC7/RX/DT
8
8
Oscillator
Start-up Timer
ALU<8>
8
INTRC
Oscillator
Power-on
Reset
8 MHz
Oscillator
Watchdog
Timer
T1OSO
Precision
Band Gap
Reference
Brown-out
Reset
Fail-Safe
MCLR(2)
VDD, VSS
Single-Supply
Programming
In-Circuit
PORTE
Clock Monitor
MCLR/VPP/RE3(2)
Debugger
Data
EEPROM
BOR
Timer0
CCP2
Timer1
MSSP
Timer2
Timer3
HLVD
ADC
10-bit
Comparator
CCP1
EUSART
Note 1: CCP2 is multiplexed with RC1 when configuration bit CCP2MX is set, or RB3 when CCP2MX is not set.
2: RE3 is only available when MCLR functionality is disabled.
3: OSC1/CLKI and OSC2/CLKO are only available in select oscillator modes and when these pins are not being used as digital I/O.
Refer to Section 2.0 “Oscillator Configurations” for additional information.
DS39631A-page 10
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 1-2:
PIC18F4420/4520 (40/44-PIN) BLOCK DIAGRAM
Data Bus<8>
PORTA
Table Pointer<21>
RA0/AN0
RA1/AN1
Data Latch
8
8
inc/dec logic
21
RA2/AN2/VREF-/CVREF
RA3/AN3/VREF+
RA4/T0CKI/C1OUT
RA5/AN4/SS/HLVDIN/C2OUT
OSC2/CLKO(3)/RA6
OSC1/CLKI(3)/RA7
Data Memory
( 3.9 Kbytes )
PCLATH
PCLATU
Address Latch
20
PCU PCH PCL
Program Counter
12
Data Address<12>
PORTB
31 Level Stack
STKPTR
RB0/INT0/FLT0/AN12
RB1/INT1/AN10
RB2/INT2/AN8
4
BSR
12
FSR0
FSR1
FSR2
4
Address Latch
Access
Bank
Program Memory
(16/32 Kbytes)
RB3/AN9/CCP2(1)
RB4/KBI0/AN11
RB5/KBI1/PGM
RB6/KBI2/PGC
RB7/KBI3/PGD
12
Data Latch
inc/dec
logic
8
Table Latch
Address
Decode
PORTC
ROM Latch
IR
RC0/T1OSO/T13CKI
RC1/T1OSI/CCP2(1)
RC2/CCP1/P1A
RC3/SCK/SCL
RC4/SDI/SDA
Instruction Bus <16>
RC5/SDO
RC6/TX/CK
RC7/RX/DT
8
State machine
control signals
Instruction
Decode and
Control
PRODH PRODL
8 x 8 Multiply
PORTD
3
8
RD0/PSP0:RD4/PSP4
RD5/PSP5/P1B
RD6/PSP6/P1C
W
BITOP
8
8
8
Internal
Oscillator
Block
RD7/PSP7/P1D
OSC1(3)
OSC2(3)
T1OSI
Power-up
Timer
8
8
Oscillator
Start-up Timer
ALU<8>
8
INTRC
Oscillator
Power-on
Reset
8 MHz
Oscillator
Watchdog
Timer
T1OSO
PORTE
RE0/RD/AN5
Precision
Band Gap
Reference
Brown-out
Reset
Fail-Safe
RE1/WR/AN6
RE2/CS/AN7
MCLR(2)
VDD, VSS
Single-Supply
Programming
In-Circuit
MCLR/VPP/RE3(2)
Clock Monitor
Debugger
Data
EEPROM
BOR
Timer0
Timer1
MSSP
Timer2
Timer3
HLVD
ADC
10-bit
Comparator
ECCP1
CCP2
EUSART
Note 1: CCP2 is multiplexed with RC1 when configuration bit CCP2MX is set, or RB3 when CCP2MX is not set.
2: RE3 is only available when MCLR functionality is disabled.
3: OSC1/CLKI and OSC2/CLKO are only available in select oscillator modes and when these pins are not being used as digital I/O.
Refer to Section 2.0 “Oscillator Configurations” for additional information.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 11
PIC18F2420/2520/4420/4520
TABLE 1-2:
PIC18F2420/2520 PINOUT I/O DESCRIPTIONS
Pin Number
Pin Buffer
PDIP,
SOIC
Pin Name
Description
Type Type
QFN
MCLR/VPP/RE3
MCLR
1
26
Master Clear (input) or programming voltage (input).
Master Clear (Reset) input. This pin is an active-low
Reset to the device.
I
ST
ST
VPP
RE3
P
I
Programming voltage input.
Digital input.
OSC1/CLKI/RA7
OSC1
9
6
7
Oscillator crystal or external clock input.
Oscillator crystal input or external clock source input.
ST buffer when configured in RC mode; CMOS otherwise.
External clock source input. Always associated with pin
function OSC1. (See related OSC1/CLKI, OSC2/CLKO
pins.)
I
I
ST
CLKI
CMOS
RA7
I/O
TTL
General purpose I/O pin.
OSC2/CLKO/RA6
OSC2
10
Oscillator crystal or clock output.
O
O
—
—
Oscillator crystal output. Connects to crystal or
resonator in Crystal Oscillator mode.
In RC mode, OSC2 pin outputs CLKO which has 1/4 the
frequency of OSC1 and denotes the instruction cycle rate.
General purpose I/O pin.
CLKO
RA6
I/O
TTL
Legend: TTL= TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: Default assignment for CCP2 when configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when configuration bit CCP2MX is cleared.
DS39631A-page 12
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-2:
PIC18F2420/2520 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Pin Name
Description
PORTA is a bidirectional I/O port.
PDIP,
QFN
SOIC
RA0/AN0
RA0
2
3
4
27
28
1
I/O
I
TTL
Analog
Digital I/O.
Analog input 0.
AN0
RA1/AN1
RA1
I/O
I
TTL
Analog
Digital I/O.
Analog input 1.
AN1
RA2/AN2/VREF-/CVREF
RA2
I/O
TTL
Digital I/O.
AN2
VREF-
CVREF
I
I
O
Analog
Analog
Analog
Analog input 2.
A/D reference voltage (low) input.
Comparator reference voltage output.
RA3/AN3/VREF+
RA3
5
6
7
2
3
4
I/O
I
I
TTL
Analog
Analog
Digital I/O.
Analog input 3.
A/D reference voltage (high) input.
AN3
VREF+
RA4/T0CKI/C1OUT
RA4
I/O
I
O
ST
ST
—
Digital I/O.
Timer0 external clock input.
Comparator 1 output.
T0CKI
C1OUT
RA5/AN4/SS/HLVDIN/
C2OUT
RA5
I/O
I
I
I
O
TTL
Analog
TTL
Analog
—
Digital I/O.
Analog input 4.
SPI™ slave select input.
High/Low-Voltage Detect input.
Comparator 2 output.
AN4
SS
HLVDIN
C2OUT
RA6
RA7
See the OSC2/CLKO/RA6 pin.
See the OSC1/CLKI/RA7 pin.
Legend: TTL= TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: Default assignment for CCP2 when configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when configuration bit CCP2MX is cleared.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 13
PIC18F2420/2520/4420/4520
TABLE 1-2:
PIC18F2420/2520 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Pin Name
Description
PDIP,
SOIC
Type Type
QFN
PORTB is a bidirectional I/O port. PORTB can be software
programmed for internal weak pull-ups on all inputs.
RB0/INT0/FLT0/AN12
21
18
RB0
I/O
TTL
ST
ST
Digital I/O.
INT0
FLT0
AN12
I
I
I
External interrupt 0.
PWM Fault input for CCP1.
Analog input 12.
Analog
RB1/INT1/AN10
RB1
22
23
24
25
26
27
28
19
20
21
22
23
24
25
I/O
I
I
TTL
ST
Analog
Digital I/O.
External interrupt 1.
Analog input 10.
INT1
AN10
RB2/INT2/AN8
RB2
I/O
I
I
TTL
ST
Analog
Digital I/O.
External interrupt 2.
Analog input 8.
INT2
AN8
RB3/AN9/CCP2
RB3
I/O
I
I/O
TTL
Analog
ST
Digital I/O.
Analog input 9.
Capture 2 input/Compare 2 output/PWM 2 output.
AN9
CCP2(1)
RB4/KBI0/AN11
RB4
I/O
I
I
TTL
TTL
Analog
Digital I/O.
Interrupt-on-change pin.
Analog input 11.
KBI0
AN11
RB5/KBI1/PGM
RB5
I/O
I
I/O
TTL
TTL
ST
Digital I/O.
Interrupt-on-change pin.
Low-Voltage ICSP™ Programming enable pin.
KBI1
PGM
RB6/KBI2/PGC
RB6
I/O
I
I/O
TTL
TTL
ST
Digital I/O.
Interrupt-on-change pin.
In-Circuit Debugger and ICSP programming clock pin.
KBI2
PGC
RB7/KBI3/PGD
RB7
I/O
I
I/O
TTL
TTL
ST
Digital I/O.
Interrupt-on-change pin.
In-Circuit Debugger and ICSP programming data pin.
KBI3
PGD
Legend: TTL= TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: Default assignment for CCP2 when configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when configuration bit CCP2MX is cleared.
DS39631A-page 14
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-2:
PIC18F2420/2520 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Pin Name
Description
PORTC is a bidirectional I/O port.
PDIP,
QFN
SOIC
RC0/T1OSO/T13CKI
RC0
11
12
8
9
I/O
O
I
ST
—
ST
Digital I/O.
Timer1 oscillator output.
Timer1/Timer3 external clock input.
T1OSO
T13CKI
RC1/T1OSI/CCP2
RC1
I/O
I
I/O
ST
Analog
ST
Digital I/O.
Timer1 oscillator input.
Capture 2 input/Compare 2 output/PWM 2 output.
T1OSI
CCP2(2)
RC2/CCP1
RC2
13
14
10
11
I/O
I/O
ST
ST
Digital I/O.
CCP1
Capture 1 input/Compare 1 output/PWM 1 output.
RC3/SCK/SCL
RC3
I/O
I/O
I/O
ST
ST
ST
Digital I/O.
SCK
SCL
Synchronous serial clock input/output for SPI™ mode.
Synchronous serial clock input/output for I2C™ mode.
RC4/SDI/SDA
RC4
15
12
I/O
I
I/O
ST
ST
ST
Digital I/O.
SDI
SDA
SPI data in.
I2C data I/O.
RC5/SDO
RC5
16
17
13
14
I/O
O
ST
—
Digital I/O.
SPI data out.
SDO
RC6/TX/CK
RC6
I/O
O
I/O
ST
—
ST
Digital I/O.
TX
CK
EUSART asynchronous transmit.
EUSART synchronous clock (see related RX/DT).
RC7/RX/DT
RC7
18
—
15
—
I/O
I
I/O
ST
ST
ST
Digital I/O.
RX
DT
EUSART asynchronous receive.
EUSART synchronous data (see related TX/CK).
RE3
VSS
VDD
—
P
—
—
—
See MCLR/VPP/RE3 pin.
8, 19 5, 16
20 17
Ground reference for logic and I/O pins.
Positive supply for logic and I/O pins.
CMOS = CMOS compatible input or output
P
Legend: TTL= TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
I
= Input
O
P
= Power
Note 1: Default assignment for CCP2 when configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when configuration bit CCP2MX is cleared.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 15
PIC18F2420/2520/4420/4520
TABLE 1-3:
Pin Name
PIC18F4420/4520 PINOUT I/O DESCRIPTIONS
Pin Number
Pin Buffer
Type Type
Description
PDIP QFN TQFP
MCLR/VPP/RE3
MCLR
1
18
18
Master Clear (input) or programming voltage (input).
Master Clear (Reset) input. This pin is an active-low
Reset to the device.
I
ST
VPP
RE3
P
I
Programming voltage input.
Digital input.
ST
ST
OSC1/CLKI/RA7
OSC1
13
32
30
Oscillator crystal or external clock input.
Oscillator crystal input or external clock source input.
ST buffer when configured in RC mode;
analog otherwise.
I
I
CLKI
CMOS
TTL
External clock source input. Always associated with
pin function OSC1. (See related OSC1/CLKI,
OSC2/CLKO pins.)
RA7
I/O
General purpose I/O pin.
OSC2/CLKO/RA6
OSC2
14
33
31
Oscillator crystal or clock output.
Oscillator crystal output. Connects to crystal
or resonator in Crystal Oscillator mode.
In RC mode, OSC2 pin outputs CLKO which
has 1/4 the frequency of OSC1 and denotes
the instruction cycle rate.
O
O
—
—
CLKO
RA6
I/O
TTL
General purpose I/O pin.
Legend: TTL= TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: Default assignment for CCP2 when configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when configuration bit CCP2MX is cleared.
DS39631A-page 16
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-3:
Pin Name
PIC18F4420/4520 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Description
PDIP QFN TQFP
PORTA is a bidirectional I/O port.
RA0/AN0
RA0
2
3
4
19
20
21
19
20
21
I/O
I
TTL
Analog
Digital I/O.
Analog input 0.
AN0
RA1/AN1
RA1
I/O
I
TTL
Analog
Digital I/O.
Analog input 1.
AN1
RA2/AN2/VREF-/CVREF
RA2
I/O
TTL
Digital I/O.
AN2
VREF-
CVREF
I
I
O
Analog
Analog
Analog
Analog input 2.
A/D reference voltage (low) input.
Comparator reference voltage output.
RA3/AN3/VREF+
RA3
5
6
7
22
23
24
22
23
24
I/O
I
I
TTL
Analog
Analog
Digital I/O.
Analog input 3.
A/D reference voltage (high) input.
AN3
VREF+
RA4/T0CKI/C1OUT
RA4
I/O
I
O
ST
ST
—
Digital I/O.
Timer0 external clock input.
Comparator 1 output.
T0CKI
C1OUT
RA5/AN4/SS/HLVDIN/
C2OUT
RA5
I/O
I
I
I
O
TTL
Analog
TTL
Analog
—
Digital I/O.
Analog input 4.
SPI slave select input.
High/Low-Voltage Detect input.
Comparator 2 output.
AN4
SS
HLVDIN
C2OUT
RA6
RA7
See the OSC2/CLKO/RA6 pin.
See the OSC1/CLKI/RA7 pin.
Legend: TTL= TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: Default assignment for CCP2 when configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when configuration bit CCP2MX is cleared.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 17
PIC18F2420/2520/4420/4520
TABLE 1-3:
Pin Name
PIC18F4420/4520 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Description
PDIP QFN TQFP
PORTB is a bidirectional I/O port. PORTB can be
software programmed for internal weak pull-ups on all
inputs.
RB0/INT0/FLT0/AN12
33
9
8
RB0
I/O
TTL
ST
ST
Digital I/O.
INT0
FLT0
AN12
I
I
I
External interrupt 0.
PWM Fault input for Enhanced CCP1.
Analog input 12.
Analog
RB1/INT1/AN10
RB1
34
35
36
37
38
39
10
11
12
14
15
16
9
I/O
I
I
TTL
ST
Analog
Digital I/O.
External interrupt 1.
Analog input 10.
INT1
AN10
RB2/INT2/AN8
RB2
10
11
14
15
16
I/O
I
I
TTL
ST
Analog
Digital I/O.
External interrupt 2.
Analog input 8.
INT2
AN8
RB3/AN9/CCP2
RB3
I/O
I
I/O
TTL
Analog
ST
Digital I/O.
Analog input 9.
Capture 2 input/Compare 2 output/PWM 2 output.
AN9
CCP2(1)
RB4/KBI0/AN11
RB4
I/O
I
I
TTL
TTL
Analog
Digital I/O.
Interrupt-on-change pin.
Analog input 11.
KBI0
AN11
RB5/KBI1/PGM
RB5
I/O
I
I/O
TTL
TTL
ST
Digital I/O.
Interrupt-on-change pin.
Low-Voltage ICSP™ Programming enable pin.
KBI1
PGM
RB6/KBI2/PGC
RB6
I/O
I
I/O
TTL
TTL
ST
Digital I/O.
KBI2
PGC
Interrupt-on-change pin.
In-Circuit Debugger and ICSP programming
clock pin.
RB7/KBI3/PGD
RB7
40
17
17
I/O
I
I/O
TTL
TTL
ST
Digital I/O.
KBI3
PGD
Interrupt-on-change pin.
In-Circuit Debugger and ICSP programming
data pin.
Legend: TTL= TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: Default assignment for CCP2 when configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when configuration bit CCP2MX is cleared.
DS39631A-page 18
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-3:
Pin Name
PIC18F4420/4520 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Description
PDIP QFN TQFP
PORTC is a bidirectional I/O port.
RC0/T1OSO/T13CKI
RC0
15
16
17
18
34
35
36
37
32
35
36
37
I/O
O
I
ST
—
ST
Digital I/O.
Timer1 oscillator output.
Timer1/Timer3 external clock input.
T1OSO
T13CKI
RC1/T1OSI/CCP2
RC1
I/O
I
I/O
ST
CMOS
ST
Digital I/O.
Timer1 oscillator input.
Capture 2 input/Compare 2 output/PWM 2 output.
T1OSI
CCP2(2)
RC2/CCP1/P1A
RC2
I/O
I/O
O
ST
ST
—
Digital I/O.
CCP1
P1A
Capture 1 input/Compare 1 output/PWM 1 output.
Enhanced CCP1 output.
RC3/SCK/SCL
RC3
I/O
I/O
ST
ST
Digital I/O.
SCK
Synchronous serial clock input/output for
SPI™ mode.
SCL
I/O
ST
Synchronous serial clock input/output for I2C™ mode.
RC4/SDI/SDA
RC4
23
42
42
I/O
I
I/O
ST
ST
ST
Digital I/O.
SPI data in.
I2C data I/O.
SDI
SDA
RC5/SDO
RC5
24
25
43
44
43
44
I/O
O
ST
—
Digital I/O.
SPI data out.
SDO
RC6/TX/CK
RC6
I/O
O
I/O
ST
—
ST
Digital I/O.
TX
CK
EUSART asynchronous transmit.
EUSART synchronous clock (see related RX/DT).
RC7/RX/DT
RC7
26
1
1
I/O
I
I/O
ST
ST
ST
Digital I/O.
RX
DT
EUSART asynchronous receive.
EUSART synchronous data (see related TX/CK).
Legend: TTL= TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: Default assignment for CCP2 when configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when configuration bit CCP2MX is cleared.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 19
PIC18F2420/2520/4420/4520
TABLE 1-3:
Pin Name
PIC18F4420/4520 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Description
PDIP QFN TQFP
PORTD is a bidirectional I/O port or a Parallel Slave
Port (PSP) for interfacing to a microprocessor port.
These pins have TTL input buffers when PSP module
is enabled.
RD0/PSP0
RD0
19
20
21
22
27
28
38
39
40
41
2
38
39
40
41
2
I/O
I/O
ST
TTL
Digital I/O.
Parallel Slave Port data.
PSP0
RD1/PSP1
RD1
I/O
I/O
ST
TTL
Digital I/O.
Parallel Slave Port data.
PSP1
RD2/PSP2
RD2
I/O
I/O
ST
TTL
Digital I/O.
Parallel Slave Port data.
PSP2
RD3/PSP3
RD3
I/O
I/O
ST
TTL
Digital I/O.
Parallel Slave Port data.
PSP3
RD4/PSP4
RD4
I/O
I/O
ST
TTL
Digital I/O.
Parallel Slave Port data.
PSP4
RD5/PSP5/P1B
RD5
3
3
I/O
I/O
O
ST
TTL
—
Digital I/O.
Parallel Slave Port data.
Enhanced CCP1 output.
PSP5
P1B
RD6/PSP6/P1C
RD6
29
30
4
5
4
5
I/O
I/O
O
ST
TTL
—
Digital I/O.
Parallel Slave Port data.
Enhanced CCP1 output.
PSP6
P1C
RD7/PSP7/P1D
RD7
I/O
I/O
O
ST
TTL
—
Digital I/O.
Parallel Slave Port data.
Enhanced CCP1 output.
PSP7
P1D
Legend: TTL= TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: Default assignment for CCP2 when configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when configuration bit CCP2MX is cleared.
DS39631A-page 20
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 1-3:
Pin Name
PIC18F4420/4520 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Description
PDIP QFN TQFP
PORTE is a bidirectional I/O port.
RE0/RD/AN5
RE0
8
9
25
26
27
—
25
26
27
—
I/O
I
ST
TTL
Digital I/O.
RD
Read control for Parallel Slave Port
(see also WR and CS pins).
Analog input 5.
AN5
I
Analog
RE1/WR/AN6
RE1
I/O
I
ST
TTL
Digital I/O.
WR
Write control for Parallel Slave Port
(see CS and RD pins).
Analog input 6.
AN6
I
Analog
RE2/CS/AN7
RE2
10
—
I/O
I
ST
TTL
Digital I/O.
CS
Chip Select control for Parallel Slave Port
(see related RD and WR).
Analog input 7.
AN7
RE3
I
Analog
—
—
P
See MCLR/VPP/RE3 pin.
VSS
12, 31 6, 30, 6, 29
31
—
Ground reference for logic and I/O pins.
VDD
NC
11, 32 7, 8, 7, 28
28, 29
P
—
—
Positive supply for logic and I/O pins.
No connect.
—
13 12,13,
33, 34
—
Legend: TTL= TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: Default assignment for CCP2 when configuration bit CCP2MX is set.
2: Alternate assignment for CCP2 when configuration bit CCP2MX is cleared.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 21
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 22
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 2-1:
CRYSTAL/CERAMIC
RESONATOROPERATION
(XT, LP, HS OR HSPLL
CONFIGURATION)
2.0
2.1
OSCILLATOR
CONFIGURATIONS
Oscillator Types
(1)
C1
PIC18F2420/2520/4420/4520 devices can be operated
in ten different oscillator modes. The user can program
the configuration bits, FOSC3:FOSC0, in Configuration
Register 1H to select one of these ten modes:
OSC1
To
Internal
Logic
(3)
RF
XTAL
1. LP
2. XT
3. HS
Low-Power Crystal
Sleep
(2)
RS
Crystal/Resonator
(1)
PIC18FXXXX
C2
OSC2
High-Speed Crystal/Resonator
4. HSPLL High-Speed Crystal/Resonator
with PLL enabled
Note 1: See Table 2-1 and Table 2-2 for initial values of
C1 and C2.
5. RC
External Resistor/Capacitor with
FOSC/4 output on RA6
2: A series resistor (RS) may be required for AT
strip cut crystals.
6. RCIO
External Resistor/Capacitor with I/O
on RA6
3: RF varies with the oscillator mode chosen.
7. INTIO1 Internal Oscillator with FOSC/4 output
on RA6 and I/O on RA7
TABLE 2-1:
CAPACITOR SELECTION FOR
CERAMIC RESONATORS
8. INTIO2 Internal Oscillator with I/O on RA6
and RA7
Typical Capacitor Values Used:
9. EC
External Clock with FOSC/4 output
External Clock with I/O on RA6
10. ECIO
Mode
Freq
OSC1
OSC2
XT
3.58 MHz
4.19 MHz
4 MHz
15 pF
15 pF
30 pF
50 pF
15 pF
15 pF
30 pF
50 pF
2.2
Crystal Oscillator/Ceramic
Resonators
4 MHz
In XT, LP, HS or HSPLL Oscillator modes, a crystal or
ceramic resonator is connected to the OSC1 and
OSC2 pins to establish oscillation. Figure 2-1 shows
the pin connections.
Capacitor values are for design guidance only.
Different capacitor values may be required to produce
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
VDD and temperature range for the application.
The oscillator design requires the use of a parallel cut
crystal.
See the notes following Table 2-2 for additional
information.
Note:
Use of a series cut crystal may give a fre-
quency out of the crystal manufacturer’s
specifications.
Note:
When using resonators with frequencies
above 3.5 MHz, the use of HS mode,
rather than XT mode, is recommended.
HS mode may be used at any VDD for
which the controller is rated. If HS is
selected, it is possible that the gain of the
oscillator will overdrive the resonator.
Therefore, a series resistor should be
placed between the OSC2 pin and the
resonator. As a good starting point, the
recommended value of RS is 330Ω.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 23
PIC18F2420/2520/4420/4520
An external clock source may also be connected to the
OSC1 pin in the HS mode, as shown in Figure 2-2.
TABLE 2-2:
CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
Typical Capacitor Values
FIGURE 2-2:
EXTERNAL CLOCK INPUT
OPERATION (HS OSC
CONFIGURATION)
Crystal
Freq
Tested:
Osc Type
C1
C2
LP
XT
32 kHz
30 pF
30 pF
1 MHz
4 MHz
15 pF
15 pF
15 pF
15 pF
OSC1
Clock from
Ext. System
PIC18FXXXX
(HS Mode)
HS
4 MHz
10 MHz
20 MHz
25 MHz
25 MHz
15 pF
15 pF
15 pF
0 pF
15 pF
15 pF
15 pF
5 pF
OSC2
Open
15 pF
15 pF
2.3
External Clock Input
Capacitor values are for design guidance only.
The EC and ECIO Oscillator modes require an external
clock source to be connected to the OSC1 pin. There is
no oscillator start-up time required after a Power-on
Reset or after an exit from Sleep mode.
These capacitors were tested with the crystals listed
below for basic start-up and operation. These values
are not optimized.
Different capacitor values may be required to produce
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
VDD and temperature range for the application.
In the EC Oscillator mode, the oscillator frequency
divided by 4 is available on the OSC2 pin. This signal
may be used for test purposes or to synchronize other
logic. Figure 2-3 shows the pin connections for the EC
Oscillator mode.
See the notes following this table for additional
information.
FIGURE 2-3:
EXTERNAL CLOCK
INPUT OPERATION
(EC CONFIGURATION)
Crystals Used:
32 kHz
25 MHz
1 MHz
4 MHz
10 MHz
20 MHz
OSC1/CLKI
Clock from
Ext. System
PIC18FXXXX
OSC2/CLKO
FOSC/4
Note 1: Higher capacitance increases the stability
of the oscillator but also increases the
start-up time.
The ECIO Oscillator mode functions like the EC mode,
except that the OSC2 pin becomes an additional gen-
eral purpose I/O pin. The I/O pin becomes bit 6 of
PORTA (RA6). Figure 2-4 shows the pin connections
for the ECIO Oscillator mode.
2: When operating below 3V VDD, or when
using certain ceramic resonators at any
voltage, it may be necessary to use the
HS mode or switch to a crystal oscillator.
3: Since each resonator/crystal has its own
characteristics, the user should consult
the resonator/crystal manufacturer for
FIGURE 2-4:
EXTERNAL CLOCK
INPUT OPERATION
(ECIO CONFIGURATION)
appropriate
values
of
external
components.
4: Rs may be required to avoid overdriving
OSC1/CLKI
PIC18FXXXX
I/O (OSC2)
Clock from
Ext. System
crystals with low drive level specification.
5: Always verify oscillator performance over
the VDD and temperature range that is
expected for the application.
RA6
DS39631A-page 24
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
2.4
RC Oscillator
2.5
PLL Frequency Multiplier
For timing insensitive applications, the “RC” and
“RCIO” device options offer additional cost savings.
The actual oscillator frequency is a function of several
factors:
A Phase Locked Loop (PLL) circuit is provided as an
option for users who wish to use a lower frequency
oscillator circuit or to clock the device up to its highest
rated frequency from a crystal oscillator. This may be
useful for customers who are concerned with EMI due
to high-frequency crystals or users who require higher
clock speeds from an internal oscillator.
• supply voltage
• values of the external resistor (REXT) and
capacitor (CEXT)
• operating temperature
2.5.1
HSPLL OSCILLATOR MODE
Given the same device, operating voltage and tempera-
ture and component values, there will also be unit-to-unit
frequency variations. These are due to factors such as:
The HSPLL mode makes use of the HS mode oscillator
for frequencies up to 10 MHz. A PLL then multiplies the
oscillator output frequency by 4 to produce an internal
clock frequency up to 40 MHz. The PLLEN bit is not
available in this oscillator mode.
• normal manufacturing variation
• difference in lead frame capacitance between
package types (especially for low CEXT values)
The PLL is only available to the crystal oscillator when
the FOSC3:FOSC0 configuration bits are programmed
for HSPLL mode (= 0110).
• variations within the tolerance of limits of REXT
and CEXT
In the RC Oscillator mode, the oscillator frequency
divided by 4 is available on the OSC2 pin. This signal
may be used for test purposes or to synchronize other
logic. Figure 2-5 shows how the R/C combination is
connected.
FIGURE 2-7:
PLL BLOCK DIAGRAM
(HS MODE)
HS Oscillator Enable
PLL Enable
(from Configuration Register 1H)
FIGURE 2-5:
RC OSCILLATOR MODE
VDD
OSC2
OSC1
Phase
Comparator
HS Mode
Crystal
Osc
FIN
REXT
FOUT
Internal
OSC1
Clock
Loop
Filter
CEXT
VSS
PIC18FXXXX
OSC2/CLKO
FOSC/4
÷4
VCO
SYSCLK
Recommended values: 3 kΩ ≤ REXT ≤ 100 kΩ
CEXT > 20 pF
The RCIO Oscillator mode (Figure 2-6) functions like
the RC mode, except that the OSC2 pin becomes an
additional general purpose I/O pin. The I/O pin
becomes bit 6 of PORTA (RA6).
2.5.2
PLL AND INTOSC
The PLL is also available to the internal oscillator block
in selected oscillator modes. In this configuration, the
PLL is enabled in software and generates a clock out-
put of up to 32 MHz. The operation of INTOSC with the
PLL is described in Section 2.6.4 “PLL in INTOSC
Modes”.
FIGURE 2-6:
RCIO OSCILLATOR MODE
VDD
REXT
Internal
OSC1
Clock
CEXT
PIC18FXXXX
VSS
I/O (OSC2)
RA6
Recommended values: 3 kΩ ≤ REXT ≤ 100 kΩ
CEXT > 20 pF
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 25
PIC18F2420/2520/4420/4520
When the OSCTUNE register is modified, the INTOSC
frequency will begin shifting to the new frequency. The
INTRC clock will reach the new frequency within
8 clock cycles (approximately 8 * 32 µs = 256 µs). The
INTOSC clock will stabilize within 1 ms. Code execu-
tion continues during this shift. There is no indication
that the shift has occurred.
2.6
Internal Oscillator Block
The PIC18F2420/2520/4420/4520 devices include an
internal oscillator block which generates two different
clock signals; either can be used as the microcontrol-
ler’s clock source. This may eliminate the need for
external oscillator circuits on the OSC1 and/or OSC2
pins.
The OSCTUNE register also implements the INTSRC
and PLLEN bits, which control certain features of the
internal oscillator block. The INTSRC bit allows users
to select which internal oscillator provides the clock
source when the 31 kHz frequency option is selected.
This is covered in greater detail in Section 2.7.1
“Oscillator Control Register”.
The main output (INTOSC) is an 8 MHz clock source,
which can be used to directly drive the device clock. It
also drives a postscaler, which can provide a range of
clock frequencies from 31 kHz to 4 MHz. The INTOSC
output is enabled when a clock frequency from 125 kHz
to 8 MHz is selected.
The other clock source is the internal RC oscillator
(INTRC), which provides a nominal 31 kHz output.
INTRC is enabled if it is selected as the device clock
source; it is also enabled automatically when any of the
following are enabled:
The PLLEN bit controls the operation of the frequency
multiplier, PLL, in internal oscillator modes.
2.6.4
PLL IN INTOSC MODES
The 4x frequency multiplier can be used with the inter-
nal oscillator block to produce faster device clock
speeds than are normally possible with an internal
oscillator. When enabled, the PLL produces a clock
speed of up to 32 MHz.
• Power-up Timer
• Fail-Safe Clock Monitor
• Watchdog Timer
• Two-Speed Start-up
Unlike HSPLL mode, the PLL is controlled through
software. The control bit, PLLEN (OSCTUNE<6>), is
used to enable or disable its operation.
These features are discussed in greater detail in
Section 23.0 “Special Features of the CPU”.
The clock source frequency (INTOSC direct, INTRC
direct or INTOSC postscaler) is selected by configuring
the IRCF bits of the OSCCON register (page 30).
The PLL is available when the device is configured to
use the internal oscillator block as its primary clock
source (FOSC3:FOSC0 = 1001or 1000). Additionally,
the PLL will only function when the selected output fre-
quency is either 4 MHz or 8 MHz (OSCCON<6:4> = 111
or 110). If both of these conditions are not met, the PLL
is disabled.
2.6.1
INTIO MODES
Using the internal oscillator as the clock source elimi-
nates the need for up to two external oscillator pins,
which can then be used for digital I/O. Two distinct
configurations are available:
The PLLEN control bit is only functional in those inter-
nal oscillator modes where the PLL is available. In all
other modes, it is forced to ‘0’ and is effectively
unavailable.
• In INTIO1 mode, the OSC2 pin outputs FOSC/4,
while OSC1 functions as RA7 for digital input and
output.
• In INTIO2 mode, OSC1 functions as RA7 and
OSC2 functions as RA6, both for digital input and
output.
2.6.5
INTOSC FREQUENCY DRIFT
The factory calibrates the internal oscillator block
output (INTOSC) for 8 MHz. However, this frequency
may drift as VDD or temperature changes, which can
affect the controller operation in a variety of ways. It is
possible to adjust the INTOSC frequency by modifying
the value in the OSCTUNE register. This has no effect
on the INTRC clock source frequency.
2.6.2
INTOSC OUTPUT FREQUENCY
The internal oscillator block is calibrated at the factory
to produce an INTOSC output frequency of 8.0 MHz.
The INTRC oscillator operates independently of the
INTOSC source. Any changes in INTOSC across
voltage and temperature are not necessarily reflected
by changes in INTRC and vice versa.
Tuning the INTOSC source requires knowing when to
make the adjustment, in which direction it should be
made and in some cases, how large a change is
needed. Three compensation techniques are discussed
in Section 2.6.5.1 “Compensating with the USART”,
Section 2.6.5.2 “Compensating with the Timers” and
Section 2.6.5.3 “Compensating with the CCP Module
in Capture Mode”, but other techniques may be used.
2.6.3
OSCTUNE REGISTER
The internal oscillator’s output has been calibrated at
the factory but can be adjusted in the user’s applica-
tion. This is done by writing to the OSCTUNE register
(Register 2-1).
DS39631A-page 26
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 2-1:
OSCTUNE: OSCILLATOR TUNING REGISTER
R/W-0
R/W-0(1)
U-0
—
R/W-0
TUN4
R/W-0
TUN3
R/W-0
TUN2
R/W-0
TUN1
R/W-0
TUN0
INTSRC PLLEN(1)
bit 7
bit 0
bit 7
bit 6
INTSRC: Internal Oscillator Low-Frequency Source Select bit
1= 31.25 kHz device clock derived from 8 MHz INTOSC source (divide-by-256 enabled)
0= 31 kHz device clock derived directly from INTRC internal oscillator
PLLEN: Frequency Multiplier PLL for INTOSC Enable bit(1)
1= PLL enabled for INTOSC (4 MHz and 8 MHz only)
0= PLL disabled
Note 1: Available only in certain oscillator configurations; otherwise, this bit is unavailable
and reads as ‘0’. See Section 2.6.4 “PLL in INTOSC Modes” for details.
bit 5
Unimplemented: Read as ‘0’
TUN4:TUN0: Frequency Tuning bits
01111= Maximum frequency
bit 4-0
•
•
•
•
00001
00000= Center frequency. Oscillator module is running at the calibrated frequency.
11111
•
•
•
•
10000= Minimum frequency
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
2.6.5.1
Compensating with the USART
2.6.5.3
Compensating with the CCP Module
in Capture Mode
An adjustment may be required when the USART
begins to generate framing errors or receives data with
errors while in Asynchronous mode. Framing errors
indicate that the device clock frequency is too high; to
adjust for this, decrement the value in OSCTUNE to
reduce the clock frequency. On the other hand, errors
in data may suggest that the clock speed is too low; to
compensate, increment OSCTUNE to increase the
clock frequency.
A CCP module can use free running Timer1 (or
Timer3), clocked by the internal oscillator block and an
external event with a known period (i.e., AC power fre-
quency). The time of the first event is captured in the
CCPRxH:CCPRxL registers and is recorded for use
later. When the second event causes a capture, the
time of the first event is subtracted from the time of the
second event. Since the period of the external event is
known, the time difference between events can be
calculated.
2.6.5.2
Compensating with the Timers
This technique compares device clock speed to some
reference clock. Two timers may be used; one timer is
clocked by the peripheral clock, while the other is
clocked by a fixed reference source, such as the
Timer1 oscillator.
If the measured time is much greater than the calcu-
lated time, the internal oscillator block is running too
fast; to compensate, decrement the OSCTUNE register.
If the measured time is much less than the calculated
time, the internal oscillator block is running too slow; to
compensate, increment the OSCTUNE register.
Both timers are cleared, but the timer clocked by the
reference generates interrupts. When an interrupt
occurs, the internally clocked timer is read and both
timers are cleared. If the internally clocked timer value
is greater than expected, then the internal oscillator
block is running too fast. To adjust for this, decrement
the OSCTUNE register.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 27
PIC18F2420/2520/4420/4520
The secondary oscillators are those external sources
not connected to the OSC1 or OSC2 pins. These
sources may continue to operate even after the
controller is placed in a power managed mode.
2.7
Clock Sources and Oscillator
Switching
Like previous PIC18 devices, the PIC18F2420/2520/
4420/4520 family includes a feature that allows the
device clock source to be switched from the main oscil-
lator to an alternate low-frequency clock source.
PIC18F2420/2520/4420/4520 devices offer two alternate
clock sources. When an alternate clock source is enabled,
the various power managed operating modes are avail-
able.
PIC18F2420/2520/4420/4520 devices offer the Timer1
oscillator as a secondary oscillator. This oscillator, in all
power managed modes, is often the time base for
functions such as a real-time clock.
Most often, a 32.768 kHz watch crystal is connected
between the RC0/T1OSO/T13CKI and RC1/T1OSI
pins. Like the LP mode oscillator circuit, loading
capacitors are also connected from each pin to ground.
Essentially, there are three clock sources for these
devices:
The Timer1 oscillator is discussed in greater detail in
Section 12.3 “Timer1 Oscillator”.
• Primary oscillators
• Secondary oscillators
• Internal oscillator block
In addition to being a primary clock source, the internal
oscillator block is available as a power managed
mode clock source. The INTRC source is also used as
the clock source for several special features, such as
the WDT and Fail-Safe Clock Monitor.
The primary oscillators include the External Crystal
and Resonator modes, the External RC modes, the
External Clock modes and the internal oscillator block.
The particular mode is defined by the FOSC3:FOSC0
configuration bits. The details of these modes are
covered earlier in this chapter.
The clock sources for the PIC18F2420/2520/4420/4520
devices are shown in Figure 2-8. See Section 23.0
“Special Features of the CPU” for Configuration
register details.
FIGURE 2-8:
PIC18F2420/2520/4420/4520 CLOCK DIAGRAM
PIC18F2420/2520/4420/4520
Primary Oscillator
LP, XT, HS, RC, EC
HSPLL, INTOSC/PLL
T1OSC
OSC2
Sleep
4 x PLL
OSC1
OSCTUNE<6>
Peripherals
Secondary Oscillator
T1OSO
T1OSCEN
Enable
Oscillator
T1OSI
OSCCON<6:4>
Internal Oscillator
CPU
8 MHz
OSCCON<6:4>
111
110
101
4 MHz
2 MHz
Internal
Oscillator
Block
IDLEN
Clock
Control
1 MHz
100
011
010
001
000
8 MHz
Source
500 kHz
250 kHz
125 kHz
31 kHz
8 MHz
(INTOSC)
INTRC
Source
FOSC3:FOSC0 OSCCON<1:0>
Clock Source Option
for other Modules
1
0
31 kHz (INTRC)
OSCTUNE<7>
WDT, PWRT, FSCM
and Two-Speed Start-up
DS39631A-page 28
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
The IDLEN bit determines if the device goes into Sleep
mode or one of the Idle modes when the SLEEP
instruction is executed.
2.7.1
OSCILLATOR CONTROL REGISTER
The OSCCON register (Register 2-2) controls several
aspects of the device clock’s operation, both in full
power operation and in power managed modes.
The use of the flag and control bits in the OSCCON
register is discussed in more detail in Section 3.0
“Power Managed Modes”.
The System Clock Select bits, SCS1:SCS0, select the
clock source. The available clock sources are the
primary clock (defined by the FOSC3:FOSC0 configu-
ration bits), the secondary clock (Timer1 oscillator) and
the internal oscillator block. The clock source changes
immediately after one or more of the bits is written to,
following a brief clock transition interval. The SCS bits
are cleared on all forms of Reset.
Note 1: The Timer1 oscillator must be enabled to
select the secondary clock source. The
Timer1 oscillator is enabled by setting the
T1OSCEN bit in the Timer1 Control regis-
ter (T1CON<3>). If the Timer1 oscillator
is not enabled, then any attempt to select
a secondary clock source will be ignored.
The Internal Oscillator Frequency Select bits
(IRCF2:IRCF0) select the frequency output of the
internal oscillator block to drive the device clock. The
choices are the INTRC source, the INTOSC source
(8 MHz) or one of the frequencies derived from the
INTOSC postscaler (31.25 kHz to 4 MHz). If the
internal oscillator block is supplying the device clock,
changing the states of these bits will have an immedi-
ate change on the internal oscillator’s output. On
device Resets, the default output frequency of the
internal oscillator block is set at 1 MHz.
2: It is recommended that the Timer1
oscillator be operating and stable before
selecting the secondary clock source or a
very long delay may occur while the
Timer1 oscillator starts.
2.7.2
OSCILLATOR TRANSITIONS
PIC18F2420/2520/4420/4520 devices contain circuitry
to prevent clock “glitches” when switching between
clock sources. A short pause in the device clock occurs
during the clock switch. The length of this pause is the
sum of two cycles of the old clock source and three to
four cycles of the new clock source. This formula
assumes that the new clock source is stable.
When a nominal output frequency of 31 kHz is selected
(IRCF2:IRCF0 = 000), users may choose which inter-
nal oscillator acts as the source. This is done with the
INTSRC bit in the OSCTUNE register (OSCTUNE<7>).
Setting this bit selects INTOSC as a 31.25 kHz clock
source by enabling the divide-by-256 output of the
INTOSC postscaler. Clearing INTSRC selects INTRC
(nominally 31 kHz) as the clock source.
Clock transitions are discussed in greater detail in
Section 3.1.2 “Entering Power Managed Modes”.
This option allows users to select the tunable and more
precise INTOSC as a clock source, while maintaining
power savings with a very low clock speed. Regardless
of the setting of INTSRC, INTRC always remains the
clock source for features such as the Watchdog Timer
and the Fail-Safe Clock Monitor.
The OSTS, IOFS and T1RUN bits indicate which clock
source is currently providing the device clock. The
OSTS bit indicates that the Oscillator Start-up Timer
has timed out and the primary clock is providing the
device clock in primary clock modes. The IOFS bit
indicates when the internal oscillator block has stabi-
lized and is providing the device clock in RC Clock
modes. The T1RUN bit (T1CON<6>) indicates when
the Timer1 oscillator is providing the device clock in
secondary clock modes. In power managed modes,
only one of these three bits will be set at any time. If
none of these bits are set, the INTRC is providing the
clock or the internal oscillator block has just started and
is not yet stable.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 29
PIC18F2420/2520/4420/4520
REGISTER 2-2:
OSCCON REGISTER
R/W-0
IDLEN
R/W-1
IRCF2
R/W-0
IRCF1
R/W-0
IRCF0
R(1)
R-0
R/W-0
SCS1
R/W-0
SCS0
OSTS
IOFS
bit 7
bit 0
bit 7
IDLEN: Idle Enable bit
1= Device enters Idle mode on SLEEPinstruction
0= Device enters Sleep mode on SLEEPinstruction
bit 6-4 IRCF2:IRCF0: Internal Oscillator Frequency Select bits
111= 8 MHz (INTOSC drives clock directly)
110= 4 MHz
101= 2 MHz
100= 1 MHz(3)
011= 500 kHz
010= 250 kHz
001= 125 kHz
000= 31 kHz (from either INTOSC/256 or INTRC directly)(2)
bit 3
bit 2
OSTS: Oscillator Start-up Time-out Status bit(1)
1= Oscillator start-up time-out timer has expired; primary oscillator is running
0= Oscillator start-up time-out timer is running; primary oscillator is not ready
IOFS: INTOSC Frequency Stable bit
1= INTOSC frequency is stable
0= INTOSC frequency is not stable
bit 1-0 SCS1:SCS0: System Clock Select bits
1x= Internal oscillator block
01= Secondary (Timer1) oscillator
00= Primary oscillator
Note 1: Reset state depends on state of the IESO configuration bit.
2: Source selected by the INTSRC bit (OSCTUNE<7>), see text.
3: Default output frequency of INTOSC on Reset.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS39631A-page 30
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
require a device clock source (i.e., SSP slave, PSP,
2.8
Effects of Power Managed Modes
on the Various Clock Sources
INTn pins and others). Peripherals that may add
significant current consumption are listed in
Section 26.2 “DC Characteristics”.
When PRI_IDLE mode is selected, the designated pri-
mary oscillator continues to run without interruption.
For all other power managed modes, the oscillator
using the OSC1 pin is disabled. The OSC1 pin (and
OSC2 pin, if used by the oscillator) will stop oscillating.
2.9
Power-up Delays
Power-up delays are controlled by two timers, so that
no external Reset circuitry is required for most applica-
tions. The delays ensure that the device is kept in
Reset until the device power supply is stable under nor-
mal circumstances and the primary clock is operating
and stable. For additional information on power-up
delays, see Section 4.5 “Device Reset Timers”.
In secondary clock modes (SEC_RUN and
SEC_IDLE), the Timer1 oscillator is operating and pro-
viding the device clock. The Timer1 oscillator may also
run in all power managed modes if required to clock
Timer1 or Timer3.
In internal oscillator modes (RC_RUN and RC_IDLE),
the internal oscillator block provides the device clock
source. The 31 kHz INTRC output can be used directly
to provide the clock and may be enabled to support
various special features, regardless of the power
managed mode (see Section 23.2 “Watchdog Timer
(WDT)”, Section 23.3 “Two-Speed Start-up” and
Section 23.4 “Fail-Safe Clock Monitor” for more
information on WDT, Fail-Safe Clock Monitor and Two-
Speed Start-up). The INTOSC output at 8 MHz may be
used directly to clock the device or may be divided
down by the postscaler. The INTOSC output is disabled
if the clock is provided directly from the INTRC output.
The first timer is the Power-up Timer (PWRT), which
provides a fixed delay on power-up (parameter 33,
Table 26-10). It is enabled by clearing (= 0) the
PWRTEN configuration bit.
The second timer is the Oscillator Start-up Timer
(OST), intended to keep the chip in Reset until the
crystal oscillator is stable (LP, XT and HS modes). The
OST does this by counting 1024 oscillator cycles
before allowing the oscillator to clock the device.
When the HSPLL Oscillator mode is selected, the
device is kept in Reset for an additional 2 ms, following
the HS mode OST delay, so the PLL can lock to the
incoming clock frequency.
If the Sleep mode is selected, all clock sources are
stopped. Since all the transistor switching currents
have been stopped, Sleep mode achieves the lowest
current consumption of the device (only leakage
currents).
There is a delay of interval TCSD (parameter 38,
Table 26-10), following POR, while the controller
becomes ready to execute instructions. This delay runs
concurrently with any other delays. This may be the
only delay that occurs when any of the EC, RC or INTIO
modes are used as the primary clock source.
Enabling any on-chip feature that will operate during
Sleep will increase the current consumed during Sleep.
The INTRC is required to support WDT operation. The
Timer1 oscillator may be operating to support a real-
time clock. Other features may be operating that do not
TABLE 2-3:
OSC1 AND OSC2 PIN STATES IN SLEEP MODE
OSC1 Pin
OSC Mode
OSC2 Pin
RC, INTIO1
RCIO
Floating, external resistor should pull high
Floating, external resistor should pull high
Configured as PORTA, bit 7
At logic low (clock/4 output)
Configured as PORTA, bit 6
Configured as PORTA, bit 6
Configured as PORTA, bit 6
At logic low (clock/4 output)
INTIO2
ECIO
Floating, pulled by external clock
Floating, pulled by external clock
EC
LP, XT and HS
Feedback inverter disabled at quiescent
voltage level
Feedback inverter disabled at quiescent
voltage level
Note:
See Table 4-2 in Section 4.0 “Reset” for time-outs due to Sleep and MCLR Reset.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 31
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 32
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
3.1.1
CLOCK SOURCES
3.0
POWER MANAGED MODES
The SCS1:SCS0 bits allow the selection of one of three
clock sources for power managed modes. They are:
PIC18F2420/2520/4420/4520 devices offer a total of
seven operating modes for more efficient power man-
agement. These modes provide a variety of options for
selective power conservation in applications where
resources may be limited (i.e., battery-powered
devices).
• the primary clock, as defined by the
FOSC3:FOSC0 configuration bits
• the secondary clock (the Timer1 oscillator)
• the internal oscillator block (for RC modes)
There are three categories of power managed modes:
3.1.2
ENTERING POWER MANAGED
MODES
• Run modes
• Idle modes
• Sleep mode
Switching from one power managed mode to another
begins by loading the OSCCON register. The
SCS1:SCS0 bits select the clock source and determine
which Run or Idle mode is to be used. Changing these
bits causes an immediate switch to the new clock
source, assuming that it is running. The switch may
also be subject to clock transition delays. These are
discussed in Section 3.1.3 “Clock Transitions and
Status Indicators” and subsequent sections.
These categories define which portions of the device
are clocked and sometimes, what speed. The Run and
Idle modes may use any of the three available clock
sources (primary, secondary or internal oscillator
block); the Sleep mode does not use a clock source.
The power managed modes include several power-
saving features offered on previous PICmicro®
devices. One is the clock switching feature, offered in
other PIC18 devices, allowing the controller to use the
Timer1 oscillator in place of the primary oscillator. Also
included is the Sleep mode, offered by all PICmicro
devices, where all device clocks are stopped.
Entry to the Power Managed Idle or Sleep modes is
triggered by the execution of a SLEEPinstruction. The
actual mode that results depends on the status of the
IDLEN bit.
Depending on the current mode and the mode being
switched to, a change to a power managed mode does
not always require setting all of these bits. Many
transitions may be done by changing the oscillator select
bits, or changing the IDLEN bit, prior to issuing a SLEEP
instruction. If the IDLEN bit is already configured
correctly, it may only be necessary to perform a SLEEP
instruction to switch to the desired mode.
3.1
Selecting Power Managed Modes
Selecting a power managed mode requires two
decisions: if the CPU is to be clocked or not and the
selection of
(OSCCON<7>) controls CPU clocking, while the
SCS1:SCS0 bits (OSCCON<1:0>) select the clock
source. The individual modes, bit settings, clock sources
and affected modules are summarized in Table 3-1.
a
clock source. The IDLEN bit
TABLE 3-1:
Mode
POWER MANAGED MODES
OSCCON Bits
Module Clocking
IDLEN(1) SCS1:SCS0
Available Clock and Oscillator Source
CPU
Peripherals
<7>
<1:0>
Sleep
0
N/A
Off
Off
None – All clocks are disabled
PRI_RUN
N/A
00
Clocked
Clocked
Primary – LP, XT, HS, HSPLL, RC, EC and
Internal Oscillator Block(2)
.
This is the normal full power execution mode.
Secondary – Timer1 Oscillator
Internal Oscillator Block(2)
SEC_RUN
RC_RUN
PRI_IDLE
SEC_IDLE
RC_IDLE
N/A
N/A
1
01
1x
00
01
1x
Clocked
Clocked
Off
Clocked
Clocked
Clocked
Clocked
Clocked
Primary – LP, XT, HS, HSPLL, RC, EC
Secondary – Timer1 Oscillator
Internal Oscillator Block(2)
1
Off
1
Off
Note 1: IDLEN reflects its value when the SLEEPinstruction is executed.
2: Includes INTOSC and INTOSC postscaler, as well as the INTRC source.
2004 Microchip Technology Inc.
DS39631A-page 33
PIC18F2420/2520/4420/4520
3.1.3
CLOCK TRANSITIONS AND STATUS
INDICATORS
3.2
Run Modes
In the Run modes, clocks to both the core and
peripherals are active. The difference between these
modes is the clock source.
The length of the transition between clock sources is
the sum of two cycles of the old clock source and three
to four cycles of the new clock source. This formula
assumes that the new clock source is stable.
3.2.1
PRI_RUN MODE
Three bits indicate the current clock source and its
status. They are:
The PRI_RUN mode is the normal, full power execution
mode of the microcontroller. This is also the default
mode upon a device Reset, unless Two-Speed Start-up
is enabled (see Section 23.3 “Two-Speed Start-up”
for details). In this mode, the OSTS bit is set. The IOFS
bit may be set if the internal oscillator block is the pri-
mary clock source (see Section 2.7.1 “Oscillator
Control Register”).
• OSTS (OSCCON<3>)
• IOFS (OSCCON<2>)
• T1RUN (T1CON<6>)
In general, only one of these bits will be set while in a
given power managed mode. When the OSTS bit is
set, the primary clock is providing the device clock.
When the IOFS bit is set, the INTOSC output is
providing a stable 8 MHz clock source to a divider that
actually drives the device clock. When the T1RUN bit is
set, the Timer1 oscillator is providing the clock. If none
of these bits are set, then either the INTRC clock
source is clocking the device, or the INTOSC source is
not yet stable.
3.2.2
SEC_RUN MODE
The SEC_RUN mode is the compatible mode to the
“clock switching” feature offered in other PIC18
devices. In this mode, the CPU and peripherals are
clocked from the Timer1 oscillator. This gives users the
option of lower power consumption while still using a
high accuracy clock source.
If the internal oscillator block is configured as the pri-
mary clock source by the FOSC3:FOSC0 configuration
bits, then both the OSTS and IOFS bits may be set
when in PRI_RUN or PRI_IDLE modes. This indicates
that the primary clock (INTOSC output) is generating a
stable 8 MHz output. Entering another RC Power
Managed mode at the same frequency would clear the
OSTS bit.
SEC_RUN mode is entered by setting the SCS1:SCS0
bits to ‘01’. The device clock source is switched to the
Timer1 oscillator (see Figure 3-1), the primary oscilla-
tor is shut down, the T1RUN bit (T1CON<6>) is set and
the OSTS bit is cleared.
Note:
The Timer1 oscillator should already be
running prior to entering SEC_RUN mode.
If the T1OSCEN bit is not set when the
SCS1:SCS0 bits are set to ‘01’, entry to
SEC_RUN mode will not occur. If the
Timer1 oscillator is enabled, but not yet
running, device clocks will be delayed until
the oscillator has started; in such situa-
tions, initial oscillator operation is far from
stable and unpredictable operation may
result.
Note 1: Caution should be used when modifying a
single IRCF bit. If VDD is less than 3V, it is
possible to select a higher clock speed
than is supported by the low VDD.
Improper device operation may result if
the VDD/FOSC specifications are violated.
2: Executing a SLEEP instruction does not
necessarily place the device into Sleep
mode. It acts as the trigger to place the
controller into either the Sleep mode or
one of the Idle modes, depending on the
setting of the IDLEN bit.
On transitions from SEC_RUN mode to PRI_RUN, the
peripherals and CPU continue to be clocked from the
Timer1 oscillator while the primary clock is started.
When the primary clock becomes ready, a clock switch
back to the primary clock occurs (see Figure 3-2).
When the clock switch is complete, the T1RUN bit is
cleared, the OSTS bit is set and the primary clock is
providing the clock. The IDLEN and SCS bits are not
affected by the wake-up; the Timer1 oscillator
continues to run.
3.1.4
MULTIPLE SLEEP COMMANDS
The power managed mode that is invoked with the
SLEEP instruction is determined by the setting of the
IDLEN bit at the time the instruction is executed. If
another SLEEPinstruction is executed, the device will
enter the power managed mode specified by IDLEN at
that time. If IDLEN has changed, the device will enter
the new power managed mode specified by the new
setting.
DS39631A-page 34
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 3-1:
TRANSITION TIMING FOR ENTRY TO SEC_RUN MODE
Q1 Q2 Q3 Q4 Q1
Q2
Q3
Q4
Q1
Q2
Q3
1
2
3
n-1
n
T1OSI
Clock Transition(1)
OSC1
CPU
Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
PC + 4
Note 1: Clock transition typically occurs within 2-4 TOSC.
FIGURE 3-2:
TRANSITION TIMING FROM SEC_RUN MODE TO PRI_RUN MODE (HSPLL)
Q1
Q2
Q3
Q4
Q1
Q2 Q3 Q4 Q1 Q2 Q3
T1OSI
OSC1
(1)
TOST
(1)
TPLL
1
2
n-1 n
PLL Clock
Output
Clock
Transition(2)
CPU Clock
Peripheral
Clock
Program
Counter
PC + 2
PC + 4
PC
OSTS bit set
SCS1:SCS0 bits changed
Note1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
2: Clock transition typically occurs within 2-4 TOSC.
This mode is entered by setting the SCS1 bit to ‘1’.
Although it is ignored, it is recommended that the SCS0
bit also be cleared; this is to maintain software compat-
ibility with future devices. When the clock source is
switched to the INTOSC multiplexer (see Figure 3-3),
the primary oscillator is shut down and the OSTS bit is
cleared. The IRCF bits may be modified at any time to
immediately change the clock speed.
3.2.3
RC_RUN MODE
In RC_RUN mode, the CPU and peripherals are
clocked from the internal oscillator block using the
INTOSC multiplexer. In this mode, the primary clock is
shut down. When using the INTRC source, this mode
provides the best power conservation of all the Run
modes, while still executing code. It works well for user
applications which are not highly timing sensitive or do
not require high-speed clocks at all times.
Note:
Caution should be used when modifying a
single IRCF bit. If VDD is less than 3V, it is
possible to select a higher clock speed
than is supported by the low VDD.
Improper device operation may result if
the VDD/FOSC specifications are violated.
If the primary clock source is the internal oscillator
block (either INTRC or INTOSC), there are no distin-
guishable differences between PRI_RUN and
RC_RUN modes during execution. However, a clock
switch delay will occur during entry to and exit from
RC_RUN mode. Therefore, if the primary clock source
is the internal oscillator block, the use of RC_RUN
mode is not recommended.
2004 Microchip Technology Inc.
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PIC18F2420/2520/4420/4520
If the IRCF bits and the INTSRC bit are all clear, the
INTOSC output is not enabled and the IOFS bit will
remain clear; there will be no indication of the current
clock source. The INTRC source is providing the
device clocks.
On transitions from RC_RUN mode to PRI_RUN mode,
the device continues to be clocked from the INTOSC
multiplexer while the primary clock is started. When the
primary clock becomes ready, a clock switch to the pri-
mary clock occurs (see Figure 3-4). When the clock
switch is complete, the IOFS bit is cleared, the OSTS
bit is set and the primary clock is providing the device
clock. The IDLEN and SCS bits are not affected by the
switch. The INTRC source will continue to run if either
the WDT or the Fail-Safe Clock Monitor is enabled.
If the IRCF bits are changed from all clear (thus,
enabling the INTOSC output) or if INTSRC is set, the
IOFS bit becomes set after the INTOSC output
becomes stable. Clocks to the device continue while
the INTOSC source stabilizes after an interval of
TIOBST.
If the IRCF bits were previously at a non-zero value, or
if INTSRC was set before setting SCS1 and the
INTOSC source was already stable, the IOFS bit will
remain set.
FIGURE 3-3:
TRANSITION TIMING TO RC_RUN MODE
Q1 Q2 Q3 Q4 Q1
Q2
Q3
Q4
Q1
Q2
Q3
1
2
3
n-1
n
INTRC
OSC1
Clock Transition(1)
CPU
Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
PC + 4
Note 1: Clock transition typically occurs within 2-4 TOSC.
FIGURE 3-4:
TRANSITION TIMING FROM RC_RUN MODE TO PRI_RUN MODE
Q3
Q4
Q1
Q2 Q3 Q4 Q1 Q2 Q3
Q1
Q2
INTOSC
Multiplexer
OSC1
(1)
TOST
(1)
TPLL
1
2
n-1
n
PLL Clock
Output
Clock
Transition(2)
CPU Clock
Peripheral
Clock
Program
Counter
PC + 2
PC + 4
PC
SCS1:SCS0 bits changed
OSTS bit set
Note1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
2: Clock transition typically occurs within 2-4 TOSC.
DS39631A-page 36
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
3.3
Sleep Mode
3.4
Idle Modes
The Power Managed Sleep mode in the PIC18F2420/
2520/4420/4520 devices is identical to the legacy
Sleep mode offered in all other PICmicro devices. It is
entered by clearing the IDLEN bit (the default state on
device Reset) and executing the SLEEP instruction.
This shuts down the selected oscillator (Figure 3-5). All
clock source status bits are cleared.
The Idle modes allow the controller’s CPU to be
selectively shut down while the peripherals continue to
operate. Selecting a particular Idle mode allows users
to further manage power consumption.
If the IDLEN bit is set to a ‘1’ when a SLEEPinstruction is
executed, the peripherals will be clocked from the clock
source selected using the SCS1:SCS0 bits; however, the
CPU will not be clocked. The clock source status bits are
not affected. Setting IDLEN and executing a SLEEP
instruction provides a quick method of switching from a
given Run mode to its corresponding Idle mode.
Entering the Sleep mode from any other mode does not
require a clock switch. This is because no clocks are
needed once the controller has entered Sleep. If the
WDT is selected, the INTRC source will continue to
operate. If the Timer1 oscillator is enabled, it will also
continue to run.
If the WDT is selected, the INTRC source will continue
to operate. If the Timer1 oscillator is enabled, it will also
continue to run.
When a wake event occurs in Sleep mode (by interrupt,
Reset or WDT time-out), the device will not be clocked
until the clock source selected by the SCS1:SCS0 bits
becomes ready (see Figure 3-6), or it will be clocked
from the internal oscillator block if either the Two-
Speed Start-up or the Fail-Safe Clock Monitor are
enabled (see Section 23.0 “Special Features of the
CPU”). In either case, the OSTS bit is set when the
primary clock is providing the device clocks. The
IDLEN and SCS bits are not affected by the wake-up.
Since the CPU is not executing instructions, the only
exits from any of the Idle modes are by interrupt, WDT
time-out or a Reset. When a wake event occurs, CPU
execution is delayed by an interval of TCSD
(parameter 38, Table 26-10) while it becomes ready to
execute code. When the CPU begins executing code,
it resumes with the same clock source for the current
Idle mode. For example, when waking from RC_IDLE
mode, the internal oscillator block will clock the CPU
and peripherals (in other words, RC_RUN mode). The
IDLEN and SCS bits are not affected by the wake-up.
While in any Idle mode or the Sleep mode, a WDT
time-out will result in a WDT wake-up to the Run mode
currently specified by the SCS1:SCS0 bits.
FIGURE 3-5:
TRANSITION TIMING FOR ENTRY TO SLEEP MODE
Q1 Q2 Q3 Q4 Q1
OSC1
CPU
Clock
Peripheral
Clock
Sleep
Program
Counter
PC
PC + 2
FIGURE 3-6:
TRANSITION TIMING FOR WAKE FROM SLEEP (HSPLL)
Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Q2 Q3 Q4 Q1 Q2
Q1
OSC1
(1)
(1)
TOST
TPLL
PLL Clock
Output
CPU Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
PC + 4
PC + 6
Wake Event
Note1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
OSTS bit set
2004 Microchip Technology Inc.
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PIC18F2420/2520/4420/4520
ting the IDLEN bit and executing a SLEEPinstruction. If
the device is in another Run mode, set the IDLEN bit
first, then set the SCS1:SCS0 bits to ‘01’ and execute
SLEEP. When the clock source is switched to the
Timer1 oscillator, the primary oscillator is shut down,
the OSTS bit is cleared and the T1RUN bit is set.
3.4.1
PRI_IDLE MODE
This mode is unique among the three Low-Power Idle
modes, in that it does not disable the primary device
clock. For timing sensitive applications, this allows for
the fastest resumption of device operation with its more
accurate primary clock source, since the clock source
does not have to “warm-up” or transition from another
oscillator.
When a wake event occurs, the peripherals continue to
be clocked from the Timer1 oscillator. After an interval
of TCSD following the wake event, the CPU begins exe-
cuting code being clocked by the Timer1 oscillator. The
IDLEN and SCS bits are not affected by the wake-up;
the Timer1 oscillator continues to run (see Figure 3-8).
PRI_IDLE mode is entered from PRI_RUN mode by
setting the IDLEN bit and executing a SLEEPinstruc-
tion. If the device is in another Run mode, set IDLEN
first, then clear the SCS bits and execute SLEEP.
Although the CPU is disabled, the peripherals continue
to be clocked from the primary clock source specified
by the FOSC3:FOSC0 configuration bits. The OSTS bit
remains set (see Figure 3-7).
Note:
The Timer1 oscillator should already be
running prior to entering SEC_IDLE mode.
If the T1OSCEN bit is not set when the
SLEEPinstruction is executed, the SLEEP
instruction will be ignored and entry to
SEC_IDLE mode will not occur. If the
Timer1 oscillator is enabled but not yet
running, peripheral clocks will be delayed
until the oscillator has started. In such sit-
uations, initial oscillator operation is far
from stable and unpredictable operation
may result.
When a wake event occurs, the CPU is clocked from the
primary clock source. A delay of interval TCSD is
required between the wake event and when code
execution starts. This is required to allow the CPU to
become ready to execute instructions. After the wake-
up, the OSTS bit remains set. The IDLEN and SCS bits
are not affected by the wake-up (see Figure 3-8).
3.4.2
SEC_IDLE MODE
In SEC_IDLE mode, the CPU is disabled but the
peripherals continue to be clocked from the Timer1
oscillator. This mode is entered from SEC_RUN by set-
FIGURE 3-7:
TRANSITION TIMING FOR ENTRY TO IDLE MODE
Q3
Q4
Q1
Q1
Q2
OSC1
CPU Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
FIGURE 3-8:
TRANSITION TIMING FOR WAKE FROM IDLE TO RUN MODE
Q1
Q3
Q4
Q2
OSC1
TCSD
CPU Clock
Peripheral
Clock
Program
Counter
PC
Wake Event
DS39631A-page 38
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
On all exits from Idle or Sleep modes by interrupt, code
execution branches to the interrupt vector if the GIE/
GIEH bit (INTCON<7>) is set. Otherwise, code execu-
tion continues or resumes without branching (see
Section 9.0 “Interrupts”).
3.4.3
RC_IDLE MODE
In RC_IDLE mode, the CPU is disabled but the periph-
erals continue to be clocked from the internal oscillator
block using the INTOSC multiplexer. This mode allows
for controllable power conservation during Idle periods.
A fixed delay of interval TCSD following the wake event
is required when leaving Sleep and Idle modes. This
delay is required for the CPU to prepare for execution.
Instruction execution resumes on the first clock cycle
following this delay.
From RC_RUN, this mode is entered by setting the
IDLEN bit and executing a SLEEP instruction. If the
device is in another Run mode, first set IDLEN, then set
the SCS1 bit and execute SLEEP. Although its value is
ignored, it is recommended that SCS0 also be cleared;
this is to maintain software compatibility with future
devices. The INTOSC multiplexer may be used to
select a higher clock frequency by modifying the IRCF
bits before executing the SLEEPinstruction. When the
clock source is switched to the INTOSC multiplexer, the
primary oscillator is shut down and the OSTS bit is
cleared.
3.5.2
EXIT BY WDT TIME-OUT
A WDT time-out will cause different actions depending
on which power managed mode the device is in when
the time-out occurs.
If the device is not executing code (all Idle modes and
Sleep mode), the time-out will result in an exit from the
power managed mode (see Section 3.2 “Run Modes”
and Section 3.3 “Sleep Mode”). If the device is exe-
cuting code (all Run modes), the time-out will result in
a WDT Reset (see Section 23.2 “Watchdog Timer
(WDT)”).
If the IRCF bits are set to any non-zero value, or the
INTSRC bit is set, the INTOSC output is enabled. The
IOFS bit becomes set, after the INTOSC output
becomes stable, after an interval of TIOBST
(parameter 39, Table 26-10). Clocks to the peripherals
continue while the INTOSC source stabilizes. If the
IRCF bits were previously at a non-zero value, or
INTSRC was set before the SLEEPinstruction was exe-
cuted and the INTOSC source was already stable, the
IOFS bit will remain set. If the IRCF bits and INTSRC
are all clear, the INTOSC output will not be enabled, the
IOFS bit will remain clear and there will be no indication
of the current clock source.
The WDT timer and postscaler are cleared by
executing a SLEEPor CLRWDTinstruction, the loss of a
currently selected clock source (if the Fail-Safe Clock
Monitor is enabled) and modifying the IRCF bits in the
OSCCON register if the internal oscillator block is the
device clock source.
3.5.3
EXIT BY RESET
When a wake event occurs, the peripherals continue to
be clocked from the INTOSC multiplexer. After a delay
of TCSD following the wake event, the CPU begins exe-
cuting code being clocked by the INTOSC multiplexer.
The IDLEN and SCS bits are not affected by the wake-
up. The INTRC source will continue to run if either the
WDT or the Fail-Safe Clock Monitor is enabled.
Normally, the device is held in Reset by the Oscillator
Start-up Timer (OST) until the primary clock becomes
ready. At that time, the OSTS bit is set and the device
begins executing code. If the internal oscillator block is
the new clock source, the IOFS bit is set instead.
The exit delay time from Reset to the start of code
execution depends on both the clock sources before
and after the wake-up and the type of oscillator if the
new clock source is the primary clock. Exit delays are
summarized in Table 3-2.
3.5
Exiting Idle and Sleep Modes
An exit from Sleep mode or any of the Idle modes is
triggered by an interrupt, a Reset or a WDT time-out.
This section discusses the triggers that cause exits
from power managed modes. The clocking subsystem
actions are discussed in each of the power managed
modes (see Section 3.2 “Run Modes”, Section 3.3
“Sleep Mode” and Section 3.4 “Idle Modes”).
Code execution can begin before the primary clock
becomes ready. If either the Two-Speed Start-up (see
Section 23.3 “Two-Speed Start-up”) or Fail-Safe
Clock Monitor (see Section 23.4 “Fail-Safe Clock
Monitor”) is enabled, the device may begin execution
as soon as the Reset source has cleared. Execution is
clocked by the INTOSC multiplexer driven by the inter-
nal oscillator block. Execution is clocked by the internal
oscillator block until either the primary clock becomes
ready or a power managed mode is entered before the
primary clock becomes ready; the primary clock is then
shut down.
3.5.1
EXIT BY INTERRUPT
Any of the available interrupt sources can cause the
device to exit from an Idle mode or the Sleep mode to
a Run mode. To enable this functionality, an interrupt
source must be enabled by setting its enable bit in one
of the INTCON or PIE registers. The exit sequence is
initiated when the corresponding interrupt flag bit is set.
2004 Microchip Technology Inc.
DS39631A-page 39
PIC18F2420/2520/4420/4520
In these instances, the primary clock source either
does not require an oscillator start-up delay since it is
already running (PRI_IDLE), or normally does not
require an oscillator start-up delay (RC, EC and INTIO
Oscillator modes). However, a fixed delay of interval
TCSD following the wake event is still required when
leaving Sleep and Idle modes to allow the CPU to
prepare for execution. Instruction execution resumes
on the first clock cycle following this delay.
3.5.4
EXIT WITHOUT AN OSCILLATOR
START-UP DELAY
Certain exits from power managed modes do not
invoke the OST at all. There are two cases:
• PRI_IDLE mode, where the primary clock source
is not stopped and
• the primary clock source is not any of the LP, XT,
HS or HSPLL modes.
TABLE 3-2:
EXIT DELAY ON WAKE-UP BY RESET FROM SLEEP MODE OR ANY IDLE MODE
(BY CLOCK SOURCES)
Clock Source
before Wake-up
Clock Source
after Wake-up
Clock Ready Status
Bit (OSCCON)
Exit Delay
LP, XT, HS
HSPLL
OSTS
IOFS
OSTS
IOFS
OSTS
IOFS
OSTS
IOFS
Primary Device Clock
(PRI_IDLE mode)
(1)
TCSD
EC, RC
INTOSC(2)
LP, XT, HS
HSPLL
(3)
TOST
(3)
TOST + trc
T1OSC or INTRC(1)
(1)
EC, RC
TCSD
INTOSC(1)
LP, XT, HS
HSPLL
TIOBST
(4)
(4)
TOST
(3)
TOST + trc
INTOSC(2)
(1)
EC, RC
TCSD
INTOSC(1)
LP, XT, HS
HSPLL
None
(3)
TOST
(3)
TOST + trc
None
(Sleep mode)
(1)
EC, RC
INTOSC(1)
TCSD
(4)
TIOBST
Note 1: TCSD (parameter 38) is a required delay when waking from Sleep and all Idle modes and runs concurrently
with any other required delays (see Section 3.4 “Idle Modes”). On Reset, INTOSC defaults to 1 MHz.
2: Includes both the INTOSC 8 MHz source and postscaler derived frequencies.
3: TOST is the Oscillator Start-up Timer (parameter 32). trc is the PLL Lock-out Timer (parameter F12); it is
also designated as TPLL.
4: Execution continues during TIOBST (parameter 39), the INTOSC stabilization period.
DS39631A-page 40
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
A simplified block diagram of the On-Chip Reset Circuit
is shown in Figure 4-1.
4.0
RESET
The PIC18F2420/2520/4420/4520 devices differentiate
between various kinds of Reset:
4.1
RCON Register
a) Power-on Reset (POR)
Device Reset events are tracked through the RCON
register (Register 4-1). The lower five bits of the regis-
ter indicate that a specific Reset event has occurred. In
most cases, these bits can only be cleared by the event
and must be set by the application after the event. The
state of these flag bits, taken together, can be read to
indicate the type of Reset that just occurred. This is
described in more detail in Section 4.6 “Reset State
of Registers”.
b) MCLR Reset during normal operation
c) MCLR Reset during power managed modes
d) Watchdog Timer (WDT) Reset (during
execution)
e) Programmable Brown-out Reset (BOR)
f) RESETInstruction
g) Stack Full Reset
h) Stack Underflow Reset
The RCON register also has control bits for setting
interrupt priority (IPEN) and software control of the
BOR (SBOREN). Interrupt priority is discussed in
Section 9.0 “Interrupts”. BOR is covered in
Section 4.4 “Brown-out Reset (BOR)”.
This section discusses Resets generated by MCLR,
POR and BOR and covers the operation of the various
start-up timers. Stack Reset events are covered in
Section 5.1.2.4 “Stack Full and Underflow Resets”.
WDT Resets are covered in Section 23.2 “Watchdog
Timer (WDT)”.
FIGURE 4-1:
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
RESET
Instruction
Stack Full/Underflow Reset
Stack
Pointer
External Reset
MCLRE
MCLR
( )_IDLE
Sleep
WDT
Time-out
VDD Rise
Detect
POR Pulse
BOREN
VDD
Brown-out
Reset
S
OST/PWRT
OST
10-bit Ripple Counter
1024 Cycles
Chip_Reset
R
Q
OSC1
32 µs
65.5 ms
PWRT
11-bit Ripple Counter
INTRC(1)
Enable PWRT
(2)
Enable OST
Note 1: This is the INTRC source from the internal oscillator block and is separate from the RC oscillator of the CLKI pin.
2: See Table 4-2 for time-out situations.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 41
PIC18F2420/2520/4420/4520
REGISTER 4-1:
RCON REGISTER
R/W-0
IPEN
R/W-1(1)
U-0
—
R/W-1
RI
R-1
TO
R-1
PD
R/W-0(2)
POR
R/W-0
BOR
SBOREN
bit 7
bit 0
bit 7
bit 6
IPEN: Interrupt Priority Enable bit
1= Enable priority levels on interrupts
0= Disable priority levels on interrupts (PIC16CXXX Compatibility mode)
SBOREN: BOR Software Enable bit(1)
If BOREN1:BOREN0 = 01:
1= BOR is enabled
0= BOR is disabled
If BOREN1:BOREN0 = 00, 10or 11:
Bit is disabled and read as ‘0’.
bit 5
bit 4
Unimplemented: Read as ‘0’
RI: RESETInstruction Flag bit
1= The RESETinstruction was not executed (set by firmware only)
0= The RESETinstruction was executed causing a device Reset (must be set in software after
a Brown-out Reset occurs)
bit 3
bit 2
bit 1
bit 0
TO: Watchdog Time-out Flag bit
1= Set by power-up, CLRWDTinstruction or SLEEPinstruction
0= A WDT time-out occurred
PD: Power-down Detection Flag bit
1= Set by power-up or by the CLRWDTinstruction
0= Set by execution of the SLEEPinstruction
POR: Power-on Reset Status bit(2)
1= A Power-on Reset has not occurred (set by firmware only)
0= A Power-on Reset occurred (must be set in software after a Power-on Reset occurs)
BOR: Brown-out Reset Status bit
1= A Brown-out Reset has not occurred (set by firmware only)
0= A Brown-out Reset occurred (must be set in software after a Brown-out Reset occurs)
Note 1: If SBOREN is enabled, its Reset state is ‘1’; otherwise, it is ‘0’.
2: The actual Reset value of POR is determined by the type of device Reset. See the
notes following this register and Section 4.6 “Reset State of Registers” for
additional information.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
Note 1: It is recommended that the POR bit be set after a Power-on Reset has been
detected so that subsequent Power-on Resets may be detected.
2: Brown-out Reset is said to have occurred when BOR is ‘0’ and POR is ‘1’ (assuming
that POR was set to ‘1’ by software immediately after POR).
DS39631A-page 42
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 4-2:
EXTERNAL POWER-ON
RESET CIRCUIT (FOR
SLOW VDD POWER-UP)
4.2
Master Clear (MCLR)
The MCLR pin provides a method for triggering an
external Reset of the device. A Reset is generated by
holding the pin low. These devices have a noise filter in
the MCLR Reset path which detects and ignores small
pulses.
VDD
VDD
D
The MCLR pin is not driven low by any internal Resets,
including the WDT.
R
R1
MCLR
In PIC18F2420/2520/4420/4520 devices, the MCLR
input can be disabled with the MCLRE configuration bit.
When MCLR is disabled, the pin becomes a digital
input. See Section 10.5 “PORTE, TRISE and LATE
Registers” for more information.
PIC18FXXXX
C
Note 1: External Power-on Reset circuit is required
only if the VDD power-up slope is too slow.
The diode D helps discharge the capacitor
quickly when VDD powers down.
4.3
Power-on Reset (POR)
A
Power-on Reset pulse is generated on-chip
2: R < 40 kΩ is recommended to make sure that
the voltage drop across R does not violate
the device’s electrical specification.
whenever VDD rises above a certain threshold. This
allows the device to start in the initialized state when
VDD is adequate for operation.
3: R1 ≥ 1 kΩ will limit any current flowing into
MCLR from external capacitor C, in the event
of MCLR/VPP pin breakdown, due to
Electrostatic Discharge (ESD) or Electrical
Overstress (EOS).
To take advantage of the POR circuitry, tie the MCLR
pin through a resistor (1 kΩ to 10 kΩ) to VDD. This will
eliminate external RC components usually needed to
create a Power-on Reset delay. A minimum rise rate for
VDD is specified (parameter D004). For a slow rise
time, see Figure 4-2.
When the device starts normal operation (i.e., exits the
Reset condition), device operating parameters (volt-
age, frequency, temperature, etc.) must be met to
ensure operation. If these conditions are not met, the
device must be held in Reset until the operating
conditions are met.
POR events are captured by the POR bit (RCON<1>).
The state of the bit is set to ‘0’ whenever a POR occurs;
it does not change for any other Reset event. POR is
not reset to ‘1’ by any hardware event. To capture
multiple events, the user manually resets the bit to ‘1’
in software following any POR.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 43
PIC18F2420/2520/4420/4520
Placing the BOR under software control gives the user
the additional flexibility of tailoring the application to its
environment without having to reprogram the device to
change BOR configuration. It also allows the user to
tailor device power consumption in software by elimi-
nating the incremental current that the BOR consumes.
While the BOR current is typically very small, it may
have some impact in low-power applications.
4.4
Brown-out Reset (BOR)
PIC18F2420/2520/4420/4520 devices implement
BOR circuit that provides the user with a number of
configuration and power-saving options. The BOR is
a
controlled
by
the
BORV1:BORV0
and
BOREN1:BOREN0 configuration bits. There are a total
of four BOR configurations which are summarized in
Table 4-1.
Note:
Even when BOR is under software control,
the BOR Reset voltage level is still set by
the BORV1:BORV0 configuration bits. It
cannot be changed in software.
The BOR threshold is set by the BORV1:BORV0 bits. If
BOR is enabled (any values of BOREN1:BOREN0,
except ‘00’), any drop of VDD below VBOR (parameter
D005) for greater than TBOR (parameter 35) will reset
the device. A Reset may or may not occur if VDD falls
below VBOR for less than TBOR. The chip will remain in
Brown-out Reset until VDD rises above VBOR.
4.4.2
DETECTING BOR
When BOR is enabled, the BOR bit always resets to ‘0’
on any BOR or POR event. This makes it difficult to
determine if a BOR event has occurred just by reading
the state of BOR alone. A more reliable method is to
simultaneously check the state of both POR and BOR.
This assumes that the POR bit is reset to ‘1’ in software
immediately after any POR event. If BOR is ‘0’ while
POR is ‘1’, it can be reliably assumed that a BOR event
has occurred.
If the Power-up Timer is enabled, it will be invoked after
VDD rises above VBOR; it then will keep the chip in
Reset for an additional time delay, TPWRT
(parameter 33). If VDD drops below VBOR while the
Power-up Timer is running, the chip will go back into a
Brown-out Reset and the Power-up Timer will be
initialized. Once VDD rises above VBOR, the Power-up
Timer will execute the additional time delay.
4.4.3
DISABLING BOR IN SLEEP MODE
BOR and the Power-on Timer (PWRT) are
independently configured. Enabling BOR Reset does
not automatically enable the PWRT.
When BOREN1:BOREN0 = 10, the BOR remains
under hardware control and operates as previously
described. Whenever the device enters Sleep mode,
however, the BOR is automatically disabled. When the
device returns to any other operating mode, BOR is
automatically re-enabled.
4.4.1
SOFTWARE ENABLED BOR
When BOREN1:BOREN0 = 01, the BOR can be
enabled or disabled by the user in software. This is
done with the control bit, SBOREN (RCON<6>).
Setting SBOREN enables the BOR to function as
previously described. Clearing SBOREN disables the
BOR entirely. The SBOREN bit operates only in this
mode; otherwise it is read as ‘0’.
This mode allows for applications to recover from
brown-out situations, while actively executing code,
when the device requires BOR protection the most. At
the same time, it saves additional power in Sleep mode
by eliminating the small incremental BOR current.
TABLE 4-1:
BOREN1
BOR CONFIGURATIONS
BOR Configuration
Status of
SBOREN
BOR Operation
BOREN0
(RCON<6>)
0
0
1
0
1
0
Unavailable BOR disabled; must be enabled by reprogramming the configuration bits.
Available BOR enabled in software; operation controlled by SBOREN.
Unavailable BOR enabled in hardware in Run and Idle modes, disabled during
Sleep mode.
1
1
Unavailable BOR enabled in hardware; must be disabled by reprogramming the
configuration bits.
DS39631A-page 44
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
4.5.3
PLL LOCK TIME-OUT
4.5
Device Reset Timers
With the PLL enabled in its PLL mode, the time-out
sequence following a Power-on Reset is slightly differ-
ent from other oscillator modes. A separate timer is
used to provide a fixed time-out that is sufficient for the
PLL to lock to the main oscillator frequency. This PLL
lock time-out (TPLL) is typically 2 ms and follows the
oscillator start-up time-out.
PIC18F2420/2520/4420/4520 devices incorporate three
separate on-chip timers that help regulate the Power-on
Reset process. Their main function is to ensure that the
device clock is stable before code is executed. These
timers are:
• Power-up Timer (PWRT)
• Oscillator Start-up Timer (OST)
• PLL Lock Time-out
4.5.4
TIME-OUT SEQUENCE
On power-up, the time-out sequence is as follows:
4.5.1
POWER-UP TIMER (PWRT)
1. After the POR pulse has cleared, PWRT time-out
is invoked (if enabled).
The Power-up Timer (PWRT) of PIC18F2420/2520/
4420/4520 devices is an 11-bit counter which uses
the INTRC source as the clock input. This yields an
approximate time interval of 2048 x 32 µs = 65.6 ms.
While the PWRT is counting, the device is held in
Reset.
2. Then, the OST is activated.
The total time-out will vary based on oscillator configu-
ration and the status of the PWRT. Figure 4-3,
Figure 4-4, Figure 4-5, Figure 4-6 and Figure 4-7 all
depict time-out sequences on power-up, with the
Power-up Timer enabled and the device operating in
HS Oscillator mode. Figures 4-3 through 4-6 also
apply to devices operating in XT or LP modes. For
devices in RC mode and with the PWRT disabled, on
the other hand, there will be no time-out at all.
The power-up time delay depends on the INTRC clock
and will vary from chip to chip due to temperature and
process variation. See DC parameter 33 for details.
The PWRT is enabled by clearing the PWRTEN
configuration bit.
Since the time-outs occur from the POR pulse, if MCLR
is kept low long enough, all time-outs will expire. Bring-
ing MCLR high will begin execution immediately
(Figure 4-5). This is useful for testing purposes or to
synchronize more than one PIC18FXXXX device
operating in parallel.
4.5.2
OSCILLATOR START-UP TIMER
(OST)
The Oscillator Start-up Timer (OST) provides a 1024
oscillator cycle (from OSC1 input) delay after the
PWRT delay is over (parameter 33). This ensures that
the crystal oscillator or resonator has started and
stabilized.
The OST time-out is invoked only for XT, LP, HS and
HSPLL modes and only on Power-on Reset, or on exit
from most power managed modes.
TABLE 4-2:
Oscillator
TIME-OUT IN VARIOUS SITUATIONS
Power-up(2) and Brown-out
Exit from
Configuration
Power Managed Mode
PWRTEN = 0
PWRTEN = 1
HSPLL
66 ms(1) + 1024 TOSC + 2 ms(2)
66 ms(1) + 1024 TOSC
66 ms(1)
1024 TOSC + 2 ms(2)
1024 TOSC + 2 ms(2)
HS, XT, LP
EC, ECIO
1024 TOSC
1024 TOSC
—
—
—
—
—
—
RC, RCIO
66 ms(1)
66 ms(1)
INTIO1, INTIO2
Note 1: 66 ms (65.5 ms) is the nominal Power-up Timer (PWRT) delay.
2: 2 ms is the nominal time required for the PLL to lock.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 45
PIC18F2420/2520/4420/4520
FIGURE 4-3:
TIME-OUT SEQUENCE ON POWER-UP (MCLR TIED TO VDD, VDD RISE < TPWRT)
VDD
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
OST TIME-OUT
TOST
INTERNAL RESET
FIGURE 4-4:
TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 1
VDD
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
OST TIME-OUT
TOST
INTERNAL RESET
FIGURE 4-5:
TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 2
VDD
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
OST TIME-OUT
TOST
INTERNAL RESET
DS39631A-page 46
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 4-6:
SLOW RISE TIME (MCLR TIED TO VDD, VDD RISE > TPWRT)
5V
0V
VDD
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
TOST
OST TIME-OUT
INTERNAL RESET
FIGURE 4-7:
TIME-OUT SEQUENCE ON POR W/PLL ENABLED (MCLR TIED TO VDD)
VDD
MCLR
INTERNAL POR
TPWRT
PWRT TIME-OUT
OST TIME-OUT
TOST
TPLL
PLL TIME-OUT
INTERNAL RESET
Note:
TOST = 1024 clock cycles.
TPLL ≈ 2 ms max. First three stages of the PWRT timer.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 47
PIC18F2420/2520/4420/4520
Table 4-4 describes the Reset states for all of the
Special Function Registers. These are categorized by
Power-on and Brown-out Resets, Master Clear and
WDT Resets and WDT wake-ups.
4.6
Reset State of Registers
Most registers are unaffected by a Reset. Their status
is unknown on POR and unchanged by all other
Resets. The other registers are forced to a “Reset
state” depending on the type of Reset that occurred.
Most registers are not affected by a WDT wake-up,
since this is viewed as the resumption of normal oper-
ation. Status bits from the RCON register, RI, TO, PD,
POR and BOR, are set or cleared differently in different
Reset situations, as indicated in Table 4-3. These bits
are used in software to determine the nature of the
Reset.
TABLE 4-3:
STATUS BITS, THEIR SIGNIFICANCE AND THE INITIALIZATION CONDITION
FOR RCON REGISTER
RCON Register
STKPTR Register
Program
Counter
Condition
SBOREN
RI
TO
PD POR BOR STKFUL STKUNF
Power-on Reset
RESETInstruction
Brown-out Reset
0000h
0000h
0000h
0000h
1
1
0
1
u
1
u
1
1
1
u
1
u
0
u
u
u
0
u
0
u
0
u
u
u
0
u
u
u
u(2)
u(2)
u(2)
MCLR during Power Managed
Run Modes
MCLR during Power Managed
Idle Modes and Sleep Mode
0000h
0000h
0000h
u(2)
u(2)
u(2)
u
u
u
1
0
u
0
u
u
u
u
u
u
u
u
u
u
u
u
u
u
WDT Time-out during Full Power
or Power Managed Run Mode
MCLR during Full Power
Execution
Stack Full Reset (STVREN = 1)
0000h
0000h
u(2)
u(2)
u
u
u
u
u
u
u
u
u
u
1
u
u
1
Stack Underflow Reset
(STVREN = 1)
Stack Underflow Error (not an
actual Reset, STVREN = 0)
0000h
PC + 2
u(2)
u(2)
u(2)
u
u
u
u
0
u
u
0
0
u
u
u
u
u
u
u
u
u
1
u
u
WDT Time-out during Power
Managed Idle or Sleep Modes
Interrupt Exit from Power
Managed Modes
PC + 2(1)
Legend: u= unchanged
Note 1: When the wake-up is due to an interrupt and the GIEH or GIEL bits are set, the PC is loaded with the
interrupt vector (008h or 0018h).
2: Reset state is ‘1’ for POR and unchanged for all other Resets when software BOR is enabled
(BOREN1:BOREN0 configuration bits = 01and SBOREN = 1). Otherwise, the Reset state is ‘0’.
DS39631A-page 48
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS
MCLR Resets,
WDT Reset,
RESET Instruction,
Stack Resets
Power-on Reset,
Brown-out Reset
Wake-up via WDT
or Interrupt
Register
Applicable Devices
(3)
TOSU
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
---0 0000
0000 0000
0000 0000
00-0 0000
---0 0000
0000 0000
0000 0000
--00 0000
0000 0000
0000 0000
0000 0000
xxxx xxxx
xxxx xxxx
0000 000x
1111 -1-1
11-0 0-00
N/A
---0 0000
0000 0000
0000 0000
uu-0 0000
---0 0000
0000 0000
0000 0000
--00 0000
0000 0000
0000 0000
0000 0000
uuuu uuuu
uuuu uuuu
0000 000u
1111 -1-1
11-0 0-00
N/A
---0 uuuu
(3)
TOSH
uuuu uuuu
(3)
TOSL
uuuu uuuu
(3)
STKPTR
PCLATU
PCLATH
PCL
uu-u uuuu
---u uuuu
uuuu uuuu
(2)
PC + 2
TBLPTRU
TBLPTRH
TBLPTRL
TABLAT
PRODH
PRODL
--uu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
(1)
INTCON
INTCON2
INTCON3
INDF0
uuuu uuuu
(1)
uuuu -u-u
(1)
uu-u u-uu
N/A
N/A
POSTINC0
POSTDEC0
PREINC0
PLUSW0
FSR0H
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
---- 0000
xxxx xxxx
xxxx xxxx
N/A
---- 0000
uuuu uuuu
uuuu uuuu
N/A
---- uuuu
uuuu uuuu
uuuu uuuu
N/A
FSR0L
WREG
INDF1
POSTINC1
POSTDEC1
PREINC1
PLUSW1
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Legend:
u= unchanged, x= unknown, -= unimplemented bit, read as ‘0’, q= value depends on condition.
Shaded cells indicate conditions do not apply for the designated device.
Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).
2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector
(0008h or 0018h).
3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with
the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack.
4: See Table 4-3 for Reset value for specific condition.
5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled
as PORTA pins, they are disabled and read ‘0’.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 49
PIC18F2420/2520/4420/4520
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
MCLR Resets,
Power-on Reset,
Brown-out Reset
WDT Reset,
RESET Instruction,
Stack Resets
Wake-up via WDT
or Interrupt
Register
Applicable Devices
FSR1H
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
---- 0000
xxxx xxxx
---- 0000
N/A
---- 0000
uuuu uuuu
---- 0000
N/A
---- uuuu
uuuu uuuu
---- uuuu
N/A
FSR1L
BSR
INDF2
POSTINC2
POSTDEC2
PREINC2
PLUSW2
FSR2H
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
---- 0000
xxxx xxxx
---x xxxx
0000 0000
xxxx xxxx
1111 1111
0100 q000
0-00 0101
---- ---0
0q-1 11q0
xxxx xxxx
xxxx xxxx
0000 0000
0000 0000
1111 1111
-000 0000
xxxx xxxx
0000 0000
0000 0000
0000 0000
0000 0000
---- 0000
uuuu uuuu
---u uuuu
0000 0000
uuuu uuuu
1111 1111
0100 q000
0-00 0101
---- ---0
0q-q qquu
uuuu uuuu
uuuu uuuu
u0uu uuuu
0000 0000
1111 1111
-000 0000
uuuu uuuu
0000 0000
0000 0000
0000 0000
0000 0000
---- uuuu
uuuu uuuu
---u uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuqu
u-uu uuuu
---- ---u
uq-u qquu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
1111 1111
-uuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
FSR2L
STATUS
TMR0H
TMR0L
T0CON
OSCCON
HLVDCON
WDTCON
(4)
RCON
TMR1H
TMR1L
T1CON
TMR2
PR2
T2CON
SSPBUF
SSPADD
SSPSTAT
SSPCON1
SSPCON2
Legend:
u= unchanged, x= unknown, -= unimplemented bit, read as ‘0’, q= value depends on condition.
Shaded cells indicate conditions do not apply for the designated device.
Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).
2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector
(0008h or 0018h).
3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with
the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack.
4: See Table 4-3 for Reset value for specific condition.
5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled
as PORTA pins, they are disabled and read ‘0’.
DS39631A-page 50
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
MCLR Resets,
WDT Reset,
RESET Instruction,
Stack Resets
Power-on Reset,
Brown-out Reset
Wake-up via WDT
or Interrupt
Register
Applicable Devices
ADRESH
ADRESL
ADCON0
ADCON1
ADCON2
CCPR1H
CCPR1L
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
xxxx xxxx
xxxx xxxx
--00 0000
--00 0qqq
0-00 0000
xxxx xxxx
xxxx xxxx
0000 0000
--00 0000
xxxx xxxx
xxxx xxxx
--00 0000
01-0 0-00
0000 0000
0000 0000
0000 00--
0000 0000
0000 0111
xxxx xxxx
xxxx xxxx
0000 0000
0000 0000
0000 0000
0000 0000
0000 0000
0000 0010
0000 000x
0000 0000
0000 0000
0000 0000
xx-0 x000
uuuu uuuu
uuuu uuuu
--00 0000
--00 0qqq
0-00 0000
uuuu uuuu
uuuu uuuu
0000 0000
--00 0000
uuuu uuuu
uuuu uuuu
--00 0000
01-0 0-00
0000 0000
0000 0000
0000 00--
0000 0000
0000 0111
uuuu uuuu
uuuu uuuu
uuuu uuuu
0000 0000
0000 0000
0000 0000
0000 0000
0000 0010
0000 000x
0000 0000
0000 0000
0000 0000
uu-0 u000
uuuu uuuu
uuuu uuuu
--uu uuuu
--uu uuuu
u-uu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
--uu uuuu
uuuu uuuu
uuuu uuuu
--uu uuuu
--uu uuuu
uuuu uuuu
uuuu uuuu
uuuu uu--
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
0000 0000
uu-0 u000
CCP1CON
CCPR2H
CCPR2L
CCP2CON
BAUDCON
PWM1CON
ECCP1AS
CVRCON
CMCON
TMR3H
TMR3L
T3CON
SPBRGH
SPBRG
RCREG
TXREG
TXSTA
RCSTA
EEADR
EEDATA
EECON2
EECON1
Legend:
u= unchanged, x= unknown, -= unimplemented bit, read as ‘0’, q= value depends on condition.
Shaded cells indicate conditions do not apply for the designated device.
Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).
2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector
(0008h or 0018h).
3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with
the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack.
4: See Table 4-3 for Reset value for specific condition.
5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled
as PORTA pins, they are disabled and read ‘0’.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 51
PIC18F2420/2520/4420/4520
TABLE 4-4:
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
MCLR Resets,
Power-on Reset,
Brown-out Reset
WDT Reset,
RESET Instruction,
Stack Resets
Wake-up via WDT
or Interrupt
Register
Applicable Devices
IPR2
PIR2
PIE2
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2420
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
2520
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4420
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
4520
11-1 1111
00-0 0000
00-0 0000
1111 1111
-111 1111
0000 0000
-000 0000
0000 0000
-000 0000
00-0 0000
0000 -111
1111 1111
1111 1111
1111 1111
11-1 1111
00-0 0000
00-0 0000
1111 1111
-111 1111
0000 0000
-000 0000
0000 0000
-000 0000
00-0 0000
0000 -111
1111 1111
1111 1111
1111 1111
uu-u uuuu
(1)
uu-u uuuu
uu-u uuuu
uuuu uuuu
-uuu uuuu
IPR1
PIR1
PIE1
(1)
uuuu uuuu
(1)
-uuu uuuu
uuuu uuuu
-uuu uuuu
uu-u uuuu
uuuu -uuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
OSCTUNE
TRISE
TRISD
TRISC
TRISB
(5)
(5)
(5)
(5)
TRISA
1111 1111
1111 1111
uuuu uuuu
LATE
LATD
LATC
LATB
---- -xxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
---- -uuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
---- -uuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
(5)
(5)
(5)
(5)
LATA
xxxx xxxx
uuuu uuuu
uuuu uuuu
PORTE
PORTD
PORTC
PORTB
---- xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
---- uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
---- uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
(5)
(5)
(5)
(5)
PORTA
xx0x 0000
uu0u 0000
uuuu uuuu
Legend:
u= unchanged, x= unknown, -= unimplemented bit, read as ‘0’, q= value depends on condition.
Shaded cells indicate conditions do not apply for the designated device.
Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).
2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector
(0008h or 0018h).
3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with
the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack.
4: See Table 4-3 for Reset value for specific condition.
5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled
as PORTA pins, they are disabled and read ‘0’.
DS39631A-page 52
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
5.1
Program Memory Organization
5.0
MEMORY ORGANIZATION
PIC18 microcontrollers implement a 21-bit program
counter, which is capable of addressing a 2-Mbyte
program memory space. Accessing a location between
the upper boundary of the physically implemented
memory and the 2-Mbyte address will return all ‘0’s (a
NOPinstruction).
There are three types of memory in PIC18 Enhanced
microcontroller devices:
• Program Memory
• Data RAM
• Data EEPROM
As Harvard architecture devices, the data and program
memories use separate busses; this allows for concur-
rent access of the two memory spaces. The data
EEPROM, for practical purposes, can be regarded as
a peripheral device, since it is addressed and accessed
through a set of control registers.
The PIC18F2420 and PIC18F4420 each have
16 Kbytes of Flash memory and can store up to 8,192
single-word instructions. The PIC18F2520 and
PIC18F4520 each have 32 Kbytes of Flash memory
and can store up to 16,384 single-word instructions.
PIC18 devices have two interrupt vectors. The Reset
vector address is at 0000h and the interrupt vector
addresses are at 0008h and 0018h.
Additional detailed information on the operation of the
Flash program memory is provided in Section 6.0
“Flash Program Memory”. Data EEPROM is
discussed separately in Section 7.0 “Data EEPROM
Memory”.
The program memory map for PIC18F2420/2520/
4420/4520 devices is shown in Figure 5-1.
FIGURE 5-1:
PROGRAM MEMORY MAP AND STACK FOR
PIC18F2420/2520/4420/4520 DEVICES
PC<20:0>
CALL,RCALL,RETURN
RETFIE,RETLW
21
Stack Level 1
•
•
•
Stack Level 31
Reset Vector
0000h
High Priority Interrupt Vector
Low Priority Interrupt Vector
0008h
0018h
On-Chip
Program Memory
On-Chip
Program Memory
3FFFh
4000h
PIC18FX4X0
7FFFh
8000h
PIC18FX5X0
Read ‘0’
Read ‘0’
1FFFFFh
200000h
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 53
PIC18F2420/2520/4420/4520
The stack operates as a 31-word by 21-bit RAM and a
5-bit stack pointer, STKPTR. The stack space is not
part of either program or data space. The stack pointer
is readable and writable and the address on the top of
the stack is readable and writable through the top-of-
stack Special File Registers. Data can also be pushed
to, or popped from the stack, using these registers.
5.1.1
PROGRAM COUNTER
The Program Counter (PC) specifies the address of the
instruction to fetch for execution. The PC is 21 bits wide
and is contained in three separate 8-bit registers. The
low byte, known as the PCL register, is both readable
and writable. The high byte, or PCH register, contains
the PC<15:8> bits; it is not directly readable or writable.
Updates to the PCH register are performed through the
PCLATH register. The upper byte is called PCU. This
register contains the PC<20:16> bits; it is also not
directly readable or writable. Updates to the PCU
register are performed through the PCLATU register.
A CALLtype instruction causes a push onto the stack;
the stack pointer is first incremented and the location
pointed to by the stack pointer is written with the
contents of the PC (already pointing to the instruction
following the CALL). A RETURNtype instruction causes
a pop from the stack; the contents of the location
pointed to by the STKPTR are transferred to the PC
and then the stack pointer is decremented.
The contents of PCLATH and PCLATU are transferred
to the program counter by any operation that writes
PCL. Similarly, the upper two bytes of the program
counter are transferred to PCLATH and PCLATU by an
operation that reads PCL. This is useful for computed
offsets to the PC (see Section 5.1.4.1 “Computed
GOTO”).
The stack pointer is initialized to ‘00000’ after all
Resets. There is no RAM associated with the location
corresponding to a stack pointer value of ‘00000’; this
is only a Reset value. Status bits indicate if the stack is
full or has overflowed or has underflowed.
The PC addresses bytes in the program memory. To
prevent the PC from becoming misaligned with word
instructions, the Least Significant bit of PCL is fixed to
a value of ‘0’. The PC increments by 2 to address
sequential instructions in the program memory.
5.1.2.1
Top-of-Stack Access
Only the top of the return address stack (TOS) is
readable and writable. A set of three registers,
TOSU:TOSH:TOSL, hold the contents of the stack loca-
tion pointed to by the STKPTR register (Figure 5-2). This
allows users to implement a software stack if necessary.
After a CALL, RCALLor interrupt, the software can read
the pushed value by reading the TOSU:TOSH:TOSL
registers. These values can be placed on a user defined
software stack. At return time, the software can return
these values to TOSU:TOSH:TOSL and do a return.
The CALL, RCALL, GOTO and program branch
instructions write to the program counter directly. For
these instructions, the contents of PCLATH and
PCLATU are not transferred to the program counter.
5.1.2
RETURN ADDRESS STACK
The return address stack allows any combination of up
to 31 program calls and interrupts to occur. The PC is
pushed onto the stack when a CALLor RCALLinstruc-
tion is executed or an interrupt is Acknowledged. The
PC value is pulled off the stack on a RETURN, RETLW
or a RETFIEinstruction. PCLATU and PCLATH are not
affected by any of the RETURNor CALLinstructions.
The user must disable the global interrupt enable bits
while accessing the stack to prevent inadvertent stack
corruption.
FIGURE 5-2:
RETURN ADDRESS STACK AND ASSOCIATED REGISTERS
Return Address Stack <20:0>
11111
11110
11101
Top-of-Stack Registers
Stack Pointer
STKPTR<4:0>
TOSU
00h
TOSH
1Ah
TOSL
34h
00010
00011
00010
00001
00000
001A34h
000D58h
Top-of-Stack
DS39631A-page 54
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
When the stack has been popped enough times to
unload the stack, the next pop will return a value of zero
to the PC and sets the STKUNF bit, while the stack
pointer remains at zero. The STKUNF bit will remain
set until cleared by software or until a POR occurs.
5.1.2.2
Return Stack Pointer (STKPTR)
The STKPTR register (Register 5-1) contains the stack
pointer value, the STKFUL (stack full) status bit and the
STKUNF (stack underflow) status bits. The value of the
stack pointer can be 0 through 31. The stack pointer
increments before values are pushed onto the stack
and decrements after values are popped off the stack.
On Reset, the stack pointer value will be zero. The user
may read and write the stack pointer value. This feature
can be used by a Real-Time Operating System (RTOS)
for return stack maintenance.
Note:
Returning a value of zero to the PC on an
underflow has the effect of vectoring the
program to the Reset vector, where the
stack conditions can be verified and
appropriate actions can be taken. This is
not the same as a Reset, as the contents
of the SFRs are not affected.
After the PC is pushed onto the stack 31 times (without
popping any values off the stack), the STKFUL bit is
set. The STKFUL bit is cleared by software or by a
POR.
5.1.2.3
PUSH and POP Instructions
Since the Top-of-Stack is readable and writable, the
ability to push values onto the stack and pull values off
the stack without disturbing normal program execution
is a desirable feature. The PIC18 instruction set
includes two instructions, PUSH and POP, that permit
the TOS to be manipulated under software control.
TOSU, TOSH and TOSL can be modified to place data
or a return address on the stack.
The action that takes place when the stack becomes
full depends on the state of the STVREN (Stack Over-
flow Reset Enable) configuration bit. (Refer to
Section 23.1 “Configuration Bits” for a description of
the device configuration bits.) If STVREN is set
(default), the 31st push will push the (PC + 2) value
onto the stack, set the STKFUL bit and reset the
device. The STKFUL bit will remain set and the stack
pointer will be set to zero.
The PUSHinstruction places the current PC value onto
the stack. This increments the stack pointer and loads
the current PC value onto the stack.
If STVREN is cleared, the STKFUL bit will be set on the
31st push and the stack pointer will increment to 31.
Any additional pushes will not overwrite the 31st push
and STKPTR will remain at 31.
The POPinstruction discards the current TOS by decre-
menting the stack pointer. The previous value pushed
onto the stack then becomes the TOS value.
REGISTER 5-1:
STKPTR REGISTER
R/C-0 R/C-0
U-0
—
R/W-0
SP4
R/W-0
SP3
R/W-0
SP2
R/W-0
SP1
R/W-0
SP0
STKFUL(1) STKUNF(1)
bit 7
bit 0
bit 7
bit 6
STKFUL: Stack Full Flag bit(1)
1= Stack became full or overflowed
0= Stack has not become full or overflowed
STKUNF: Stack Underflow Flag bit(1)
1= Stack underflow occurred
0= Stack underflow did not occur
bit 5
Unimplemented: Read as ‘0’
bit 4-0
SP4:SP0: Stack Pointer Location bits
Note 1: Bit 7 and bit 6 are cleared by user software or by a POR.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented
‘0’ = Bit is cleared
C = Clearable only bit
x = Bit is unknown
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5.1.2.4
Stack Full and Underflow Resets
5.1.4
LOOK-UP TABLES IN PROGRAM
MEMORY
Device Resets on stack overflow and stack underflow
conditions are enabled by setting the STVREN bit in
Configuration Register 4L. When STVREN is set, a full
or underflow will set the appropriate STKFUL or
STKUNF bit and then cause a device Reset. When
STVREN is cleared, a full or underflow condition will set
the appropriate STKFUL or STKUNF bit but not cause
a device Reset. The STKFUL or STKUNF bits are
cleared by the user software or a Power-on Reset.
There may be programming situations that require the
creation of data structures, or look-up tables, in
program memory. For PIC18 devices, look-up tables
can be implemented in two ways:
• Computed GOTO
• Table Reads
5.1.4.1
Computed GOTO
5.1.3
FAST REGISTER STACK
A computed GOTOis accomplished by adding an offset
to the program counter. An example is shown in
Example 5-2.
A fast register stack is provided for the Status, WREG
and BSR registers, to provide a “fast return” option for
interrupts. The stack for each register is only one level
deep and is neither readable nor writable. It is loaded
with the current value of the corresponding register
when the processor vectors for an interrupt. All inter-
rupt sources will push values into the stack registers.
The values in the registers are then loaded back into
their associated registers if the RETFIE, FAST
instruction is used to return from the interrupt.
A look-up table can be formed with an ADDWF PCL
instruction and a group of RETLW nninstructions. The
W register is loaded with an offset into the table before
executing a call to that table. The first instruction of the
called routine is the ADDWF PCLinstruction. The next
instruction executed will be one of the RETLW nn
instructions that returns the value ‘nn’ to the calling
function.
If both low and high priority interrupts are enabled, the
stack registers cannot be used reliably to return from
low priority interrupts. If a high priority interrupt occurs
while servicing a low priority interrupt, the stack register
values stored by the low priority interrupt will be
overwritten. In these cases, users must save the key
registers in software during a low priority interrupt.
The offset value (in WREG) specifies the number of
bytes that the program counter should advance and
should be multiples of 2 (LSb = 0).
In this method, only one data byte may be stored in
each instruction location and room on the return
address stack is required.
If interrupt priority is not used, all interrupts may use the
fast register stack for returns from interrupt. If no inter-
rupts are used, the fast register stack can be used to
restore the Status, WREG and BSR registers at the end
of a subroutine call. To use the fast register stack for a
subroutine call, a CALLlabel, FASTinstruction must
be executed to save the Status, WREG and BSR
registers to the fast register stack. A RETURN, FAST
instruction is then executed to restore these registers
from the fast register stack.
EXAMPLE 5-2:
COMPUTED GOTO USING
AN OFFSET VALUE
OFFSET, W
TABLE
MOVF
CALL
ORG
TABLE
nn00h
ADDWF
RETLW
RETLW
RETLW
.
PCL
nnh
nnh
nnh
.
Example 5-1 shows a source code example that uses
the fast register stack during a subroutine call and
return.
.
5.1.4.2
Table Reads and Table Writes
A better method of storing data in program memory
allows two bytes of data to be stored in each instruction
location.
EXAMPLE 5-1:
FAST REGISTER STACK
CODE EXAMPLE
;STATUS, WREG, BSR
;SAVED IN FAST REGISTER
;STACK
CALL SUB1, FAST
Look-up table data may be stored two bytes per pro-
gram word by using table reads and writes. The Table
Pointer (TBLPTR) register specifies the byte address
and the Table Latch (TABLAT) register contains the
data that is read from or written to program memory.
Data is transferred to or from program memory one
byte at a time.
•
•
SUB1
•
•
RETURN, FAST
;RESTORE VALUES SAVED
;IN FAST REGISTER STACK
Table read and table write operations are discussed
further in Section 6.1 “Table Reads and Table
Writes”.
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5.2.2
INSTRUCTION FLOW/PIPELINING
5.2
PIC18 Instruction Cycle
An “Instruction Cycle” consists of four Q cycles: Q1
through Q4. The instruction fetch and execute are
pipelined in such a manner that a fetch takes one
instruction cycle, while the decode and execute take
another instruction cycle. However, due to the pipe-
lining, each instruction effectively executes in one
cycle. If an instruction causes the program counter to
change (e.g., GOTO), then two cycles are required to
complete the instruction (Example 5-3).
5.2.1
CLOCKING SCHEME
The microcontroller clock input, whether from an inter-
nal or external source, is internally divided by four to
generate four non-overlapping quadrature clocks (Q1,
Q2, Q3 and Q4). Internally, the program counter is
incremented on every Q1; the instruction is fetched
from the program memory and latched into the instruc-
tion register during Q4. The instruction is decoded and
executed during the following Q1 through Q4. The
clocks and instruction execution flow are shown in
Figure 5-3.
A fetch cycle begins with the Program Counter (PC)
incrementing in Q1.
In the execution cycle, the fetched instruction is latched
into the Instruction Register (IR) in cycle Q1. This
instruction is then decoded and executed during the
Q2, Q3 and Q4 cycles. Data memory is read during Q2
(operand read) and written during Q4 (destination
write).
FIGURE 5-3:
CLOCK/INSTRUCTION CYCLE
Q2
Q3
Q4
Q2
Q3
Q4
Q2
Q3
Q4
Q1
Q1
Q1
OSC1
Q1
Q2
Q3
Q4
Internal
Phase
Clock
PC
PC
PC + 2
PC + 4
OSC2/CLKO
(RC mode)
Execute INST (PC – 2)
Fetch INST (PC)
Execute INST (PC)
Fetch INST (PC + 2)
Execute INST (PC + 2)
Fetch INST (PC + 4)
EXAMPLE 5-3:
INSTRUCTION PIPELINE FLOW
TCY0
TCY1
TCY2
TCY3
TCY4
TCY5
1. MOVLW 55h
2. MOVWF PORTB
3. BRA SUB_1
Fetch 1
Execute 1
Fetch 2
Execute 2
Fetch 3
Execute 3
Fetch 4
4. BSF
PORTA, BIT3 (Forced NOP)
Flush (NOP)
5. Instruction @ address SUB_1
Fetch SUB_1 Execute SUB_1
All instructions are single cycle, except for any program branches. These take two cycles since the fetch instruction
is “flushed” from the pipeline while the new instruction is being fetched and then executed.
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The CALLand GOTOinstructions have the absolute pro-
gram memory address embedded into the instruction.
Since instructions are always stored on word bound-
aries, the data contained in the instruction is a word
address. The word address is written to PC<20:1>,
which accesses the desired byte address in program
memory. Instruction #2 in Figure 5-4 shows how the
instruction GOTO 0006h is encoded in the program
memory. Program branch instructions, which encode a
relative address offset, operate in the same manner. The
offset value stored in a branch instruction represents the
number of single-word instructions that the PC will be
offset by. Section 24.0 “Instruction Set Summary”
provides further details of the instruction set.
5.2.3
INSTRUCTIONS IN PROGRAM
MEMORY
The program memory is addressed in bytes. Instruc-
tions are stored as two bytes or four bytes in program
memory. The Least Significant Byte of an instruction
word is always stored in a program memory location
with an even address (LSb = 0). To maintain alignment
with instruction boundaries, the PC increments in steps
of 2 and the LSb will always read ‘0’ (see Section 5.1.1
“Program Counter”).
Figure 5-4 shows an example of how instruction words
are stored in the program memory.
FIGURE 5-4:
INSTRUCTIONS IN PROGRAM MEMORY
Word Address
LSB = 1
LSB = 0
↓
Program Memory
Byte Locations →
000000h
000002h
000004h
000006h
000008h
00000Ah
00000Ch
00000Eh
000010h
000012h
000014h
Instruction 1:
Instruction 2:
MOVLW
GOTO
055h
0006h
0Fh
EFh
F0h
C1h
F4h
55h
03h
00h
23h
56h
Instruction 3:
MOVFF
123h, 456h
the instruction sequence. If the first word is skipped for
some reason and the second word is executed by itself,
a NOPis executed instead. This is necessary for cases
when the two-word instruction is preceded by a condi-
tional instruction that changes the PC. Example 5-4
shows how this works.
5.2.4
TWO-WORD INSTRUCTIONS
The standard PIC18 instruction set has four two-word
instructions: CALL, MOVFF, GOTO and LSFR. In all
cases, the second word of the instructions always has
‘1111’ as its four Most Significant bits; the other 12 bits
are literal data, usually a data memory address.
Note:
See Section 5.6 “PIC18 Instruction
Execution and the Extended Instruc-
tion Set” for information on two-word
instructions in the extended instruction set.
The use of ‘1111’ in the 4 MSbs of an instruction spec-
ifies a special form of NOP. If the instruction is executed
in proper sequence – immediately after the first word –
the data in the second word is accessed and used by
EXAMPLE 5-4:
CASE 1:
TWO-WORD INSTRUCTIONS
Source Code
Object Code
0110 0110 0000 0000 TSTFSZ
REG1
REG1, REG2 ; No, skip this word
; Execute this word as a NOP
; continue code
; is RAM location 0?
1100 0001 0010 0011
1111 0100 0101 0110
0010 0100 0000 0000
CASE 2:
MOVFF
ADDWF
REG3
Object Code
Source Code
TSTFSZ
0110 0110 0000 0000
1100 0001 0010 0011
1111 0100 0101 0110
0010 0100 0000 0000
REG1
; is RAM location 0?
MOVFF
REG1, REG2 ; Yes, execute this word
; 2nd word of instruction
ADDWF
REG3
; continue code
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5.3.1
BANK SELECT REGISTER (BSR)
5.3
Data Memory Organization
Large areas of data memory require an efficient
addressing scheme to make rapid access to any
address possible. Ideally, this means that an entire
address does not need to be provided for each read or
write operation. For PIC18 devices, this is accom-
plished with a RAM banking scheme. This divides the
memory space into 16 contiguous banks of 256 bytes.
Depending on the instruction, each location can be
addressed directly by its full 12-bit address, or an 8-bit
low-order address and a 4-bit bank pointer.
Note:
The operation of some aspects of data
memory are changed when the PIC18
extended instruction set is enabled. See
Section 5.5 “Data Memory and the
Extended Instruction Set” for more
information.
The data memory in PIC18 devices is implemented as
static RAM. Each register in the data memory has a
12-bit address, allowing up to 4096 bytes of data
memory. The memory space is divided into as many as
16 banks that contain 256 bytes each; PIC18F2420/
2520/4420/4520 devices implement all 16 banks.
Figure 5-5 shows the data memory organization for the
PIC18F2420/2520/4420/4520 devices.
Most instructions in the PIC18 instruction set make use
of the bank pointer, known as the Bank Select Register
(BSR). This SFR holds the 4 Most Significant bits of a
location’s address; the instruction itself includes the
8 Least Significant bits. Only the four lower bits of the
BSR are implemented (BSR3:BSR0). The upper four
bits are unused; they will always read ‘0’ and cannot be
written to. The BSR can be loaded directly by using the
MOVLBinstruction.
The data memory contains Special Function Registers
(SFRs) and General Purpose Registers (GPRs). The
SFRs are used for control and status of the controller
and peripheral functions, while GPRs are used for data
storage and scratchpad operations in the user’s
application. Any read of an unimplemented location will
read as ‘0’s.
The value of the BSR indicates the bank in data
memory; the 8 bits in the instruction show the location
in the bank and can be thought of as an offset from the
bank’s lower boundary. The relationship between the
BSR’s value and the bank division in data memory is
shown in Figure 5-7.
The instruction set and architecture allow operations
across all banks. The entire data memory may be
accessed by Direct, Indirect or Indexed Addressing
modes. Addressing modes are discussed later in this
subsection.
Since up to 16 registers may share the same low-order
address, the user must always be careful to ensure that
the proper bank is selected before performing a data
read or write. For example, writing what should be
program data to an 8-bit address of F9h while the BSR
is 0Fh will end up resetting the program counter.
To ensure that commonly used registers (SFRs and
select GPRs) can be accessed in a single cycle, PIC18
devices implement an Access Bank. This is a 256-byte
memory space that provides fast access to SFRs and
the lower portion of GPR Bank 0 without using the
BSR. Section 5.3.2 “Access Bank” provides a
detailed description of the Access RAM.
While any bank can be selected, only those banks that
are actually implemented can be read or written to.
Writes to unimplemented banks are ignored, while
reads from unimplemented banks will return ‘0’s. Even
so, the Status register will still be affected as if the
operation was successful. The data memory map in
Figure 5-5 indicates which banks are implemented.
In the core PIC18 instruction set, only the MOVFF
instruction fully specifies the 12-bit address of the
source and target registers. This instruction ignores the
BSR completely when it executes. All other instructions
include only the low-order address as an operand and
must use either the BSR or the Access Bank to locate
their target registers.
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PIC18F2420/2520/4420/4520
FIGURE 5-5:
DATA MEMORY MAP FOR PIC18F2420/4420 DEVICES
When ‘a’ = 0:
BSR<3:0>
Data Memory Map
The BSR is ignored and the
Access Bank is used.
000h
07Fh
080h
0FFh
100h
00h
Access RAM
GPR
= 0000
= 0001
= 0010
The first 128 bytes are
general purpose RAM
(from Bank 0).
Bank 0
FFh
00h
The second 128 bytes are
Special Function Registers
(from Bank 15).
GPR
GPR
Bank 1
Bank 2
1FFh
200h
FFh
00h
FFh
00h
2FFh
300h
When ‘a’ = 1:
= 0011
The BSR specifies the Bank
used by the instruction.
Bank 3
Bank 4
Bank 5
Bank 6
Bank 7
Bank 8
Bank 9
Bank 10
Bank 11
Bank 12
Bank 13
3FFh
400h
FFh
00h
= 0100
= 0101
4FFh
500h
FFh
00h
5FFh
600h
FFh
00h
= 0110
= 0111
Access Bank
FFh
00h
6FFh
700h
00h
Access RAM Low
7Fh
Access RAM High
80h
FFh
00h
7FFh
800h
(SFRs)
= 1000
= 1001
FFh
8FFh
900h
FFh
00h
Unused
Read 00h
9FFh
A00h
FFh
00h
= 1010
= 1011
= 1100
= 1101
AFFh
B00h
FFh
00h
BFFh
C00h
FFh
00h
CFFh
D00h
FFh
00h
DFFh
E00h
FFh
00h
= 1110
= 1111
Bank 14
Bank 15
EFFh
F00h
F7Fh
F80h
FFFh
FFh
00h
Unused
SFR
FFh
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FIGURE 5-6:
DATA MEMORY MAP FOR PIC18F2520/4520 DEVICES
When ‘a’ = 0:
The BSR is ignored and the
BSR<3:0>
Data Memory Map
Access Bank is used.
000h
07Fh
080h
0FFh
100h
00h
Access RAM
GPR
= 0000
= 0001
= 0010
The first 128 bytes are
general purpose RAM
(from Bank 0).
Bank 0
FFh
00h
The second 128 bytes are
Special Function Registers
(from Bank 15).
GPR
GPR
GPR
GPR
GPR
Bank 1
Bank 2
1FFh
200h
FFh
00h
FFh
00h
2FFh
300h
When ‘a’ = 1:
= 0011
The BSR specifies the Bank
used by the instruction.
Bank 3
Bank 4
Bank 5
Bank 6
Bank 7
Bank 8
Bank 9
Bank 10
Bank 11
Bank 12
Bank 13
3FFh
400h
FFh
00h
= 0100
= 0101
4FFh
500h
FFh
00h
5FFh
600h
FFh
00h
= 0110
= 0111
Access Bank
FFh
00h
6FFh
700h
00h
Access RAM Low
7Fh
Access RAM High
80h
FFh
00h
7FFh
800h
(SFRs)
= 1000
= 1001
FFh
8FFh
900h
FFh
00h
9FFh
A00h
FFh
00h
Unused
Read 00h
= 1010
= 1011
= 1100
= 1101
AFFh
B00h
FFh
00h
BFFh
C00h
FFh
00h
CFFh
D00h
FFh
00h
DFFh
E00h
FFh
00h
= 1110
= 1111
Bank 14
Bank 15
EFFh
F00h
F7Fh
F80h
FFFh
FFh
00h
Unused
SFR
FFh
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FIGURE 5-7:
USE OF THE BANK SELECT REGISTER (DIRECT ADDRESSING)
Memory
Data
(2)
(1)
From Opcode
BSR
000h
100h
7
0
7
0
00h
Bank 0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
1
1
FFh
00h
Bank 1
Bank 2
(2)
Bank Select
FFh
00h
200h
300h
FFh
00h
Bank 3
through
Bank 13
FFh
00h
E00h
Bank 14
Bank 15
FFh
00h
F00h
FFFh
FFh
Note 1: The Access RAM bit of the instruction can be used to force an override of the selected bank (BSR<3:0>) to
the registers of the Access Bank.
2: The MOVFF instruction embeds the entire 12-bit address in the instruction.
however, the instruction is forced to use the Access
Bank address map; the current value of the BSR is
ignored entirely.
5.3.2
ACCESS BANK
While the use of the BSR with an embedded 8-bit
address allows users to address the entire range of
data memory, it also means that the user must always
ensure that the correct bank is selected. Otherwise,
data may be read from or written to the wrong location.
This can be disastrous if a GPR is the intended target
of an operation, but an SFR is written to instead.
Verifying and/or changing the BSR for each read or
write to data memory can become very inefficient.
Using this “forced” addressing allows the instruction to
operate on a data address in a single cycle, without
updating the BSR first. For 8-bit addresses of 80h and
above, this means that users can evaluate and operate
on SFRs more efficiently. The Access RAM below 80h
is a good place for data values that the user might need
to access rapidly, such as immediate computational
results or common program variables. Access RAM
also allows for faster and more code efficient context
saving and switching of variables.
To streamline access for the most commonly used data
memory locations, the data memory is configured with
an Access Bank, which allows users to access a
mapped block of memory without specifying a BSR.
The Access Bank consists of the first 128 bytes of
memory (00h-7Fh) in Bank 0 and the last 128 bytes of
memory (80h-FFh) in Block 15. The lower half is known
as the “Access RAM” and is composed of GPRs. This
upper half is also where the device’s SFRs are
mapped. These two areas are mapped contiguously in
the Access Bank and can be addressed in a linear
fashion by an 8-bit address (Figure 5-5).
The mapping of the Access Bank is slightly different
when the extended instruction set is enabled (XINST
configuration bit = 1). This is discussed in more detail
in Section 5.5.3 “Mapping the Access Bank in
Indexed Literal Offset Mode”.
5.3.3
GENERAL PURPOSE REGISTER
FILE
PIC18 devices may have banked memory in the GPR
area. This is data RAM, which is available for use by all
instructions. GPRs start at the bottom of Bank 0
(address 000h) and grow upwards towards the bottom of
the SFR area. GPRs are not initialized by a Power-on
Reset and are unchanged on all other Resets.
The Access Bank is used by core PIC18 instructions
that include the Access RAM bit (the ‘a’ parameter in
the instruction). When ‘a’ is equal to ‘1’, the instruction
uses the BSR and the 8-bit address included in the
opcode for the data memory address. When ‘a’ is ‘0’,
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The SFRs can be classified into two sets: those asso-
ciated with the “core” device functionality (ALU, Resets
and interrupts) and those related to the peripheral func-
tions. The reset and interrupt registers are described in
their respective chapters, while the ALU’s Status regis-
ter is described later in this section. Registers related to
the operation of a peripheral feature are described in
the chapter for that peripheral.
5.3.4
SPECIAL FUNCTION REGISTERS
The Special Function Registers (SFRs) are registers
used by the CPU and peripheral modules for controlling
the desired operation of the device. These registers are
implemented as static RAM. SFRs start at the top of
data memory (FFFh) and extend downward to occupy
the top half of Bank 15 (F80h to FFFh). A list of these
registers is given in Table 5-1 and Table 5-2.
The SFRs are typically distributed among the
peripherals whose functions they control. Unused SFR
locations are unimplemented and read as ‘0’s.
TABLE 5-1:
Address
SPECIAL FUNCTION REGISTER MAP FOR PIC18F2420/2520/4420/4520 DEVICES
Name
Address
Name
Address
FBFh
FBEh
Name
Address
F9Fh
Name
FFFh
FFEh
FFDh
FFCh
FFBh
FFAh
FF9h
FF8h
FF7h
FF6h
FF5h
FF4h
FF3h
FF2h
FF1h
FF0h
FEFh
TOSU
TOSH
FDFh
INDF2(1)
CCPR1H
CCPR1L
IPR1
PIR1
PIE1
FDEh POSTINC2(1)
FDDh POSTDEC2(1)
FDCh PREINC2(1)
FDBh PLUSW2(1)
F9Eh
F9Dh
F9Ch
TOSL
FBDh CCP1CON
(2)
STKPTR
PCLATU
PCLATH
PCL
FBCh
FBBh
CCPR2H
CCPR2L
—
F9Bh OSCTUNE
(2)
FDAh
FD9h
FD8h
FD7h
FD6h
FD5h
FD4h
FD3h
FSR2H
FSR2L
FBAh CCP2CON
F9Ah
F99h
F98h
F97h
F96h
F95h
F94h
F93h
F92h
F91h
F90h
F8Fh
F8Eh
F8Dh
F8Ch
F8Bh
F8Ah
F89h
F88h
F87h
F86h
F85h
F84h
F83h
F82h
F81h
F80h
—
—
—
—
(2)
(2)
(2)
(2)
FB9h
—
TBLPTRU
TBLPTRH
TBLPTRL
TABLAT
PRODH
PRODL
INTCON
INTCON2
INTCON3
INDF0(1)
STATUS
TMR0H
TMR0L
T0CON
FB8h BAUDCON
FB7h PWM1CON(3)
FB6h ECCP1AS(3)
TRISE(3)
TRISD(3)
TRISC
FB5h
FB4h
FB3h
FB2h
FB1h
FB0h
FAFh
FAEh
FADh
FACh
FABh
FAAh
FA9h
FA8h
CVRCON
CMCON
TMR3H
TMR3L
T3CON
SPBRGH
SPBRG
RCREG
TXREG
TXSTA
(2)
—
OSCCON
TRISB
FD2h HLVDCON
TRISA
(2)
FD1h
FD0h
FCFh
FCEh
FCDh
FCCh
FCBh
FCAh
FC9h
FC8h
FC7h
FC6h
FC5h
FC4h
FC3h
FC2h
FC1h
FC0h
WDTCON
RCON
—
(2)
—
(2)
TMR1H
—
FEEh POSTINC0(1)
FEDh POSTDEC0(1)
FECh PREINC0(1)
FEBh PLUSW0(1)
TMR1L
—
(2)
T1CON
LATE(3)
LATD(3)
LATC
TMR2
PR2
RCSTA
(2)
FEAh
FE9h
FE8h
FE7h
FE6h POSTINC1(1)
FE5h POSTDEC1(1)
FE4h PREINC1(1)
FE3h PLUSW1(1)
FSR0H
FSR0L
WREG
INDF1(1)
T2CON
—
LATB
SSPBUF
SSPADD
SSPSTAT
SSPCON1
SSPCON2
ADRESH
ADRESL
ADCON0
ADCON1
ADCON2
EEADR
LATA
(2)
EEDATA
—
FA7h EECON2(1)
—
(2)
(2)
FA6h
FA5h
FA4h
FA3h
FA2h
FA1h
FA0h
EECON1
—
(2)
(2)
—
—
(2)
—
PORTE(3)
PORTD(3)
PORTC
PORTB
(2)
—
FE2h
FE1h
FE0h
FSR1H
FSR1L
BSR
IPR2
PIR2
PIE2
PORTA
Note 1: This is not a physical register.
2: Unimplemented registers are read as ‘0’.
3: This register is not available on 28-pin devices.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 63
PIC18F2420/2520/4420/4520
TABLE 5-2:
File Name
TOSU
REGISTER FILE SUMMARY (PIC18F2420/2520/4420/4520)
Value on
POR, BOR on page:
Details
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
—
—
—
Top-of-Stack Upper Byte (TOS<20:16>)
---0 0000 49, 54
0000 0000 49, 54
0000 0000 49, 54
00-0 0000 49, 55
---0 0000 49, 54
0000 0000 49, 54
0000 0000 49, 54
--00 0000 49, 76
0000 0000 49, 76
0000 0000 49, 76
0000 0000 49, 76
xxxx xxxx 49, 89
xxxx xxxx 49, 89
0000 000x 49, 93
1111 -1-1 49, 94
11-0 0-00 49, 95
TOSH
Top-of-Stack, High Byte (TOS<15:8>)
Top-of-Stack, Low Byte (TOS<7:0>)
TOSL
STKPTR
PCLATU
PCLATH
PCL
STKFUL
—
STKUNF
—
—
—
SP4
SP3
SP2
SP1
SP0
Holding Register for PC<20:16>
Holding Register for PC<15:8>
PC, Low Byte (PC<7:0>)
TBLPTRU
TBLPTRH
TBLPTRL
TABLAT
PRODH
PRODL
INTCON
INTCON2
INTCON3
INDF0
—
—
bit 21
Program Memory Table Pointer Upper Byte (TBLPTR<20:16>)
Program Memory Table Pointer, High Byte (TBLPTR<15:8>)
Program Memory Table Pointer, Low Byte (TBLPTR<7:0>)
Program Memory Table Latch
Product Register, High Byte
Product Register, Low Byte
GIE/GIEH
RBPU
PEIE/GIEL
INTEDG0
INT1IP
TMR0IE
INTEDG1
—
INT0IE
INTEDG2
INT2IE
RBIE
—
TMR0IF
TMR0IP
—
INT0IF
—
RBIF
RBIP
INT2IP
INT1IE
INT2IF
INT1IF
Uses contents of FSR0 to address data memory – value of FSR0 not changed (not a physical register)
N/A
N/A
N/A
N/A
N/A
49, 69
49, 69
49, 69
49, 69
49, 69
POSTINC0 Uses contents of FSR0 to address data memory – value of FSR0 post-incremented (not a physical register)
POSTDEC0 Uses contents of FSR0 to address data memory – value of FSR0 post-decremented (not a physical register)
PREINC0
PLUSW0
Uses contents of FSR0 to address data memory – value of FSR0 pre-incremented (not a physical register)
Uses contents of FSR0 to address data memory – value of FSR0 pre-incremented (not a physical register) –
value of FSR0 offset by W
FSR0H
FSR0L
WREG
INDF1
—
—
—
—
Indirect Data Memory Address Pointer 0, High Byte
---- 0000 49, 69
xxxx xxxx 49, 69
Indirect Data Memory Address Pointer 0, Low Byte
Working Register
xxxx xxxx
N/A
49
Uses contents of FSR1 to address data memory – value of FSR1 not changed (not a physical register)
49, 69
49, 69
49, 69
49, 69
49, 69
POSTINC1 Uses contents of FSR1 to address data memory – value of FSR1 post-incremented (not a physical register)
POSTDEC1 Uses contents of FSR1 to address data memory – value of FSR1 post-decremented (not a physical register)
N/A
N/A
PREINC1
PLUSW1
Uses contents of FSR1 to address data memory – value of FSR1 pre-incremented (not a physical register)
N/A
Uses contents of FSR1 to address data memory – value of FSR1 pre-incremented (not a physical register) –
value of FSR1 offset by W
N/A
FSR1H
FSR1L
BSR
—
—
—
—
Indirect Data Memory Address Pointer 1, High Byte
---- 0000 50, 69
xxxx xxxx 50, 69
---- 0000 50, 59
Indirect Data Memory Address Pointer 1, Low Byte
—
—
—
—
Bank Select Register
INDF2
Uses contents of FSR2 to address data memory – value of FSR2 not changed (not a physical register)
N/A
N/A
N/A
N/A
N/A
50, 69
50, 69
50, 69
50, 69
50, 69
POSTINC2 Uses contents of FSR2 to address data memory – value of FSR2 post-incremented (not a physical register)
POSTDEC2 Uses contents of FSR2 to address data memory – value of FSR2 post-decremented (not a physical register)
PREINC2
PLUSW2
Uses contents of FSR2 to address data memory – value of FSR2 pre-incremented (not a physical register)
Uses contents of FSR2 to address data memory – value of FSR2 pre-incremented (not a physical register) –
value of FSR2 offset by W
FSR2H
FSR2L
STATUS
—
—
—
—
Indirect Data Memory Address Pointer 2, High Byte
---- 0000 50, 69
xxxx xxxx 50, 69
---x xxxx 50, 67
Indirect Data Memory Address Pointer 2, Low Byte
—
—
—
N
OV
Z
DC
C
Legend:
x= unknown, u= unchanged, —= unimplemented, q= value depends on condition
Note 1:
The SBOREN bit is only available when the BOREN1:BOREN0 configuration bits = 01; otherwise it is disabled and reads as ‘0’. See
Section 4.4 “Brown-out Reset (BOR)”.
2:
3:
4:
5:
These registers and/or bits are not implemented on 28-pin devices and are read as ‘0’. Reset values are shown for 40/44-pin devices;
individual unimplemented bits should be interpreted as ‘-’.
The PLLEN bit is only available in specific oscillator configuration; otherwise it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in
INTOSC Modes”.
The RE3 bit is only available when Master Clear Reset is disabled (MCLRE configuration bit = 0). Otherwise, RE3 reads as ‘0’. This bit is
read-only.
RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes.
When disabled, these bits read as ‘0’.
DS39631A-page 64
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 5-2:
REGISTER FILE SUMMARY (PIC18F2420/2520/4420/4520) (CONTINUED)
Value on
POR, BOR on page:
Details
File Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TMR0H
Timer0 Register, High Byte
Timer0 Register, Low Byte
0000 0000 50, 125
xxxx xxxx 50, 125
1111 1111 50, 123
0100 q000 30, 50
0-00 0101 50, 245
--- ---0 50, 259
TMR0L
T0CON
TMR0ON
IDLEN
T08BIT
IRCF2
—
T0CS
IRCF1
IRVST
—
T0SE
IRCF0
HLVDEN
—
PSA
OSTS
HLVDL3
—
T0PS2
IOFS
T0PS1
SCS1
HLVDL1
—
T0PS0
SCS0
OSCCON
HLVDCON
WDTCON
VDIRMAG
—
HLVDL2
—
HLVDL0
SWDTEN
—
RCON
IPEN
SBOREN(1)
—
RI
TO
PD
POR
BOR
0q-1 11q0 42, 48,
102
TMR1H
TMR1L
Timer1 Register, High Byte
Timer1 Register, Low Bytes
xxxx xxxx 50, 131
xxxx xxxx 50, 131
T1CON
TMR2
RD16
T1RUN
T1CKPS1
T1CKPS0
T1OSCEN
T1SYNC
TMR2ON
TMR1CS
T2CKPS1
TMR1ON 0000 0000 50, 127
0000 0000 50, 134
Timer2 Register
PR2
Timer2 Period Register
T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0
SSP Receive Buffer/Transmit Register
1111 1111 50, 134
T2CON
SSPBUF
—
T2CKPS0 -000 0000 50, 133
xxxx xxxx 50, 169,
170
SSPADD
SSPSTAT
SSP Address Register in I2C Slave Mode. SSP Baud Rate Reload Register in I2C Master Mode.
0000 0000 50, 170
SMP
WCOL
GCEN
CKE
D/A
P
S
R/W
SSPM2
PEN
UA
BF
0000 0000 50, 162,
171
SSPCON1
SSPOV
ACKSTAT
SSPEN
ACKDT
CKP
SSPM3
RCEN
SSPM1
RSEN
SSPM0
SEN
0000 0000 50, 163,
172
SSPCON2
ADRESH
ADRESL
ACKEN
0000 0000 50, 173
xxxx xxxx 51, 232
xxxx xxxx 51, 232
A/D Result Register, High Byte
A/D Result Register, Low Byte
ADCON0
ADCON1
ADCON2
CCPR1H
CCPR1L
CCP1CON
—
—
—
—
—
CHS3
VCFG1
ACQT2
CHS2
VCFG0
ACQT1
CHS1
PCFG3
ACQT0
CHS0
PCFG2
ADCS2
GO/DONE
PCFG1
ADON
PCFG0
ADCS0
--00 0000 51, 223
--00 0qqq 51, 224
0-00 0000 51, 225
xxxx xxxx 51, 140
xxxx xxxx 51, 140
ADFM
ADCS1
Capture/Compare/PWM Register 1, High Byte
Capture/Compare/PWM Register 1, Low Byte
P1M1(2)
P1M0(2)
DC1B1
DC1B0
CCP1M3
CCP1M2
CCP1M1
CCP1M0 0000 0000 51, 139,
147
CCPR2H
CCPR2L
CCP2CON
BAUDCON
PWM1CON
ECCP1AS
CVRCON
CMCON
Capture/Compare/PWM Register 2, High Byte
Capture/Compare/PWM Register 2, Low Byte
xxxx xxxx 51, 140
xxxx xxxx 51, 140
—
—
DC2B1
—
PDC5(2)
ECCPAS1
CVRR
DC2B0
SCKP
PDC4(2)
ECCPAS0
CVRSS
C1INV
CCP2M3
BRG16
PDC3(2)
PSSAC1
CVR3
CCP2M2
—
PDC2(2)
PSSAC0
CVR2
CM2
CCP2M1
WUE
PDC1(2)
CCP2M0 --00 0000 51, 139
ABDOVF
PRSEN
ECCPASE
CVREN
C2OUT
RCIDL
ABDEN
PDC0(2)
01-0 0-00 51, 204
PDC6(2)
ECCPAS2
CVROE
C1OUT
0000 0000 51, 156
PSSBD1(2) PSSBD0(2) 0000 0000 51, 157
CVR1
CM1
CVR0
CM0
0000 0000 51, 239
0000 0111 51, 233
xxxx xxxx 51, 137
xxxx xxxx 51, 137
C2INV
CIS
TMR3H
Timer3 Register, High Byte
Timer3 Register, Low Byte
TMR3L
T3CON
RD16
T3CCP2
T3CKPS1
T3CKPS0
T3CCP1
T3SYNC
TMR3CS
TMR3ON 0000 0000 51, 135
Legend:
x= unknown, u= unchanged, —= unimplemented, q= value depends on condition
Note 1:
The SBOREN bit is only available when the BOREN1:BOREN0 configuration bits = 01; otherwise it is disabled and reads as ‘0’. See
Section 4.4 “Brown-out Reset (BOR)”.
2:
3:
4:
5:
These registers and/or bits are not implemented on 28-pin devices and are read as ‘0’. Reset values are shown for 40/44-pin devices;
individual unimplemented bits should be interpreted as ‘-’.
The PLLEN bit is only available in specific oscillator configuration; otherwise it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in
INTOSC Modes”.
The RE3 bit is only available when Master Clear Reset is disabled (MCLRE configuration bit = 0). Otherwise, RE3 reads as ‘0’. This bit is
read-only.
RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes.
When disabled, these bits read as ‘0’.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 65
PIC18F2420/2520/4420/4520
TABLE 5-2:
REGISTER FILE SUMMARY (PIC18F2420/2520/4420/4520) (CONTINUED)
Value on
POR, BOR on page:
Details
File Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
SPBRGH
SPBRG
RCREG
TXREG
TXSTA
RCSTA
EEADR
EEDATA
EECON2
EECON1
IPR2
EUSART Baud Rate Generator Register, High Byte
EUSART Baud Rate Generator Register, Low Byte
EUSART Receive Register
0000 0000 51, 206
0000 0000 51, 206
0000 0000 51, 213
0000 0000 51, 211
0000 0010 51, 202
0000 000x 51, 203
0000 0000 51, 74, 83
0000 0000 51, 74, 83
0000 0000 51, 74, 83
xx-0 x000 51, 75, 84
11-1 1111 52, 101
00-0 0000 52, 97
00-0 0000 52, 99
1111 1111 52, 100
0000 0000 52, 96
0000 0000 52, 98
0q-0 0000 27, 52
0000 -111 52, 118
1111 1111 52, 114
1111 1111 52, 111
1111 1111 52, 108
1111 1111 52, 105
---- -xxx 52, 117
EUSART Transmit Register
CSRC
SPEN
TX9
RX9
TXEN
SREN
SYNC
CREN
SENDB
ADDEN
BRGH
FERR
TRMT
OERR
TX9D
RX9D
EEPROM Address Register
EEPROM Data Register
EEPROM Control Register 2 (not a physical register)
EEPGD
OSCFIP
OSCFIF
OSCFIE
PSPIP(2)
PSPIF(2)
PSPIE(2)
INTSRC
IBF
CFGS
CMIP
CMIF
CMIE
ADIP
—
—
FREE
EEIP
WRERR
BCLIP
BCLIF
BCLIE
SSPIP
SSPIF
SSPIE
TUN3
—
WREN
HLVDIP
HLVDIF
HLVDIE
CCP1IP
CCP1IF
CCP1IE
TUN2
WR
RD
TMR3IP
TMR3IF
TMR3IE
TMR2IP
TMR2IF
TMR2IE
TUN1
CCP2IP
CCP2IF
CCP2IE
TMR1IP
TMR1IF
TMR1IE
TUN0
PIR2
—
EEIF
PIE2
—
EEIE
IPR1
RCIP
RCIF
RCIE
—
TXIP
PIR1
ADIF
TXIF
PIE1
ADIE
PLLEN(3)
TXIE
OSCTUNE
TRISE(2)
TRISD(2)
TRISC
TRISB
TUN4
PSPMODE
OBF
IBOV
TRISE2
TRISE1
TRISE0
PORTD Data Direction Control Register
PORTC Data Direction Control Register
PORTB Data Direction Control Register
TRISA
LATE(2)
TRISA7(5)
TRISA6(5) Data Direction Control Register for PORTA
—
—
—
—
—
PORTE Data Latch Register
(Read and Write to Data Latch)
LATD(2)
LATC
PORTD Data Latch Register (Read and Write to Data Latch)
PORTC Data Latch Register (Read and Write to Data Latch)
PORTB Data Latch Register (Read and Write to Data Latch)
xxxx xxxx 52, 114
xxxx xxxx 52, 111
xxxx xxxx 52, 108
xxxx xxxx 52, 105
---- xxxx 52, 117
xxxx xxxx 52, 114
xxxx xxxx 52, 111
xxxx xxxx 52, 108
xx0x 0000 52, 105
LATB
LATA
LATA7(5)
LATA6(5) PORTA Data Latch Register (Read and Write to Data Latch)
PORTE
PORTD(2)
PORTC
PORTB
PORTA
—
—
—
—
RE3(4)
RD3
RC3
RB3
RE2(2)
RD2
RC2
RB2
RE1(2)
RD1
RC1
RB1
RE0(2)
RD0
RC0
RB0
RD7
RD6
RC6
RB6
RD5
RC5
RB5
RA5
RD4
RC4
RB4
RA4
RC7
RB7
RA7(5)
RA6(5)
RA3
RA2
RA1
RA0
Legend:
x= unknown, u= unchanged, —= unimplemented, q= value depends on condition
Note 1:
The SBOREN bit is only available when the BOREN1:BOREN0 configuration bits = 01; otherwise it is disabled and reads as ‘0’. See
Section 4.4 “Brown-out Reset (BOR)”.
2:
3:
4:
5:
These registers and/or bits are not implemented on 28-pin devices and are read as ‘0’. Reset values are shown for 40/44-pin devices;
individual unimplemented bits should be interpreted as ‘-’.
The PLLEN bit is only available in specific oscillator configuration; otherwise it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in
INTOSC Modes”.
The RE3 bit is only available when Master Clear Reset is disabled (MCLRE configuration bit = 0). Otherwise, RE3 reads as ‘0’. This bit is
read-only.
RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes.
When disabled, these bits read as ‘0’.
DS39631A-page 66
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
It is recommended that only BCF, BSF, SWAPF, MOVFF
and MOVWF instructions are used to alter the Status
register, because these instructions do not affect the Z,
C, DC, OV or N bits in the Status register.
5.3.5
STATUS REGISTER
The Status register, shown in Register 5-2, contains the
arithmetic status of the ALU. As with any other SFR, it
can be the operand for any instruction.
For other instructions that do not affect Status bits, see
the instruction set summaries in Table 24-2 and
Table 24-3.
If the Status register is the destination for an instruction
that affects the Z, DC, C, OV or N bits, the results of the
instruction are not written; instead, the Status register
is updated according to the instruction performed.
Therefore, the result of an instruction with the Status
register as its destination may be different than
intended. As an example, CLRF STATUSwill set the Z
bit and leave the remaining status bits unchanged
(‘000u u1uu’).
Note:
The C and DC bits operate as the borrow
and digit borrow bits, respectively, in
subtraction.
REGISTER 5-2:
STATUS REGISTER
U-0
—
U-0
—
U-0
—
R/W-x
R/W-x
OV
R/W-x
Z
R/W-x
DC
R/W-x
C
N
bit 7
bit 0
bit 7-5
bit 4
Unimplemented: Read as ‘0’
N: Negative bit
This bit is used for signed arithmetic (2’s complement). It indicates whether the result was
negative (ALU MSB = 1).
1= Result was negative
0= Result was positive
bit 3
OV: Overflow bit
This bit is used for signed arithmetic (2’s complement). It indicates an overflow of the 7-bit
magnitude which causes the sign bit (bit 7 of the result) to change state.
1= Overflow occurred for signed arithmetic (in this arithmetic operation)
0= No overflow occurred
bit 2
bit 1
Z: Zero bit
1= The result of an arithmetic or logic operation is zero
0= The result of an arithmetic or logic operation is not zero
DC: Digit Carry/borrow bit
For ADDWF, ADDLW, SUBLWand SUBWFinstructions:
1= A carry-out from the 4th low-order bit of the result occurred
0= No carry-out from the 4th low-order bit of the result
Note:
For borrow, the polarity is reversed. A subtraction is executed by adding the 2’s
complement of the second operand. For rotate (RRF, RLF) instructions, this bit is
loaded with either bit 4 or bit 3 of the source register.
bit 0
C: Carry/borrow bit
For ADDWF, ADDLW, SUBLWand SUBWFinstructions:
1= A carry-out from the Most Significant bit of the result occurred
0= No carry-out from the Most Significant bit of the result occurred
Note:
For borrow, the polarity is reversed. A subtraction is executed by adding the 2’s
complement of the second operand. For rotate (RRF, RLF) instructions, this bit is
loaded with either the high or low-order bit of the source register.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 67
PIC18F2420/2520/4420/4520
The Access RAM bit ‘a’ determines how the address is
interpreted. When ‘a’ is ‘1’, the contents of the BSR
(Section 5.3.1 “Bank Select Register (BSR)”) are
used with the address to determine the complete 12-bit
address of the register. When ‘a’ is ‘0’, the address is
interpreted as being a register in the Access Bank.
Addressing that uses the Access RAM is sometimes
also known as Direct Forced Addressing mode.
5.4
Data Addressing Modes
Note:
The execution of some instructions in the
core PIC18 instruction set are changed
when the PIC18 extended instruction set is
enabled. See Section 5.5 “Data Memory
and the Extended Instruction Set” for
more information.
A few instructions, such as MOVFF, include the entire
12-bit address (either source or destination) in their
opcodes. In these cases, the BSR is ignored entirely.
While the program memory can be addressed in only
one way – through the program counter – information
in the data memory space can be addressed in several
ways. For most instructions, the addressing mode is
fixed. Other instructions may use up to three modes,
depending on which operands are used and whether or
not the extended instruction set is enabled.
The destination of the operation’s results is determined
by the destination bit ‘d’. When ‘d’ is ‘1’, the results are
stored back in the source register, overwriting its origi-
nal contents. When ‘d’ is ‘0’, the results are stored in
the W register. Instructions without the ‘d’ argument
have a destination that is implicit in the instruction; their
destination is either the target register being operated
on or the W register.
The addressing modes are:
• Inherent
• Literal
• Direct
5.4.3
INDIRECT ADDRESSING
• Indirect
Indirect addressing allows the user to access a location
in data memory without giving a fixed address in the
instruction. This is done by using File Select Registers
(FSRs) as pointers to the locations to be read or written
to. Since the FSRs are themselves located in RAM as
Special File Registers, they can also be directly manip-
ulated under program control. This makes FSRs very
useful in implementing data structures, such as tables
and arrays in data memory.
An additional addressing mode, Indexed Literal Offset,
is available when the extended instruction set is
enabled (XINST configuration bit = 1). Its operation is
discussed in greater detail in Section 5.5.1 “Indexed
Addressing with Literal Offset”.
5.4.1
INHERENT AND LITERAL
ADDRESSING
Many PIC18 control instructions do not need any argu-
ment at all; they either perform an operation that glo-
bally affects the device or they operate implicitly on one
register. This addressing mode is known as Inherent
Addressing. Examples include SLEEP, RESETand DAW.
The registers for indirect addressing are also
implemented with Indirect File Operands (INDFs) that
permit automatic manipulation of the pointer value with
auto-incrementing, auto-decrementing or offsetting
with another value. This allows for efficient code, using
loops, such as the example of clearing an entire RAM
bank in Example 5-5.
Other instructions work in a similar way but require an
additional explicit argument in the opcode. This is
known as Literal Addressing mode because they
require some literal value as an argument. Examples
include ADDLWand MOVLW, which respectively, add or
move a literal value to the W register. Other examples
include CALL and GOTO, which include a 20-bit
program memory address.
EXAMPLE 5-5:
HOW TO CLEAR RAM
(BANK 1) USING
INDIRECT ADDRESSING
LFSR
FSR0, 100h ;
NEXT
CLRF
POSTINC0
; Clear INDF
; register then
; inc pointer
; All done with
; Bank1?
; NO, clear next
; YES, continue
5.4.2
DIRECT ADDRESSING
Direct addressing specifies all or part of the source
and/or destination address of the operation within the
opcode itself. The options are specified by the
arguments accompanying the instruction.
BTFSS
BRA
FSR0H, 1
NEXT
CONTINUE
In the core PIC18 instruction set, bit-oriented and byte-
oriented instructions use some version of direct
addressing by default. All of these instructions include
some 8-bit literal address as their Least Significant
Byte. This address specifies either a register address in
one of the banks of data RAM (Section 5.3.3 “General
Purpose Register File”) or a location in the Access
Bank (Section 5.3.2 “Access Bank”) as the data
source for the instruction.
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5.4.3.1
FSR Registers and the INDF
Operand
5.4.3.2
FSR Registers and POSTINC,
POSTDEC, PREINC and PLUSW
At the core of indirect addressing are three sets of reg-
isters: FSR0, FSR1 and FSR2. Each represents a pair
of 8-bit registers, FSRnH and FSRnL. The four upper
bits of the FSRnH register are not used so each FSR
pair holds a 12-bit value. This represents a value that
can address the entire range of the data memory in a
linear fashion. The FSR register pairs, then, serve as
pointers to data memory locations.
In addition to the INDF operand, each FSR register pair
also has four additional indirect operands. Like INDF,
these are “virtual” registers that cannot be indirectly
read or written to. Accessing these registers actually
accesses the associated FSR register pair, but also
performs a specific action on it stored value. They are:
• POSTDEC: accesses the FSR value, then
automatically decrements it by 1 afterwards
Indirect addressing is accomplished with a set of
Indirect File Operands, INDF0 through INDF2. These
can be thought of as “virtual” registers: they are
mapped in the SFR space but are not physically imple-
mented. Reading or writing to a particular INDF register
actually accesses its corresponding FSR register pair.
A read from INDF1, for example, reads the data at the
address indicated by FSR1H:FSR1L. Instructions that
use the INDF registers as operands actually use the
contents of their corresponding FSR as a pointer to the
instruction’s target. The INDF operand is just a
convenient way of using the pointer.
• POSTINC: accesses the FSR value, then
automatically increments it by 1 afterwards
• PREINC: increments the FSR value by 1, then
uses it in the operation
• PLUSW: adds the signed value of the W register
(range of -127 to 128) to that of the FSR and uses
the new value in the operation.
In this context, accessing an INDF register uses the
value in the FSR registers without changing them. Sim-
ilarly, accessing a PLUSW register gives the FSR value
offset by that in the W register; neither value is actually
changed in the operation. Accessing the other virtual
registers changes the value of the FSR registers.
Because indirect addressing uses a full 12-bit address,
data RAM banking is not necessary. Thus, the current
contents of the BSR and the Access RAM bit have no
effect on determining the target address.
Operations on the FSRs with POSTDEC, POSTINC
and PREINC affect the entire register pair; that is, roll-
overs of the FSRnL register from FFh to 00h carry over
to the FSRnH register. On the other hand, results of
these operations do not change the value of any flags
in the Status register (e.g., Z, N, OV, etc.).
FIGURE 5-8:
INDIRECT ADDRESSING
000h
Using an instruction with one of the
indirect addressing registers as the
operand....
Bank 0
Bank 1
ADDWF, INDF1, 1
100h
200h
300h
Bank 2
FSR1H:FSR1L
...uses the 12-bit address stored in
the FSR pair associated with that
register....
7
0
7
0
Bank 3
through
Bank 13
x x x x 1 1 1 0
1 1 0 0 1 1 0 0
...to determine the data memory
location to be used in that operation.
E00h
In this case, the FSR1 pair contains
ECCh. This means the contents of
location ECCh will be added to that
of the W register and stored back in
ECCh.
Bank 14
Bank 15
F00h
FFFh
Data Memory
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The PLUSW register can be used to implement a form
of indexed addressing in the data memory space. By
manipulating the value in the W register, users can
reach addresses that are fixed offsets from pointer
addresses. In some applications, this can be used to
implement some powerful program control structure,
such as software stacks, inside of data memory.
5.5.1
INDEXED ADDRESSING WITH
LITERAL OFFSET
Enabling the PIC18 extended instruction set changes
the behavior of indirect addressing using the FSR2
register pair within Access RAM. Under the proper
conditions, instructions that use the Access Bank – that
is, most bit-oriented and byte-oriented instructions –
can invoke a form of indexed addressing using an
offset specified in the instruction. This special address-
ing mode is known as Indexed Addressing with Literal
Offset, or Indexed Literal Offset mode.
5.4.3.3
Operations by FSRs on FSRs
Indirect addressing operations that target other FSRs
or virtual registers represent special cases. For exam-
ple, using an FSR to point to one of the virtual registers
will not result in successful operations. As a specific
case, assume that FSR0H:FSR0L contains FE7h, the
address of INDF1. Attempts to read the value of the
INDF1 using INDF0 as an operand will return 00h.
Attempts to write to INDF1 using INDF0 as the operand
will result in a NOP.
When using the extended instruction set, this
addressing mode requires the following:
• The use of the Access Bank is forced (‘a’ = 0) and
• The file address argument is less than or equal to
5Fh.
Under these conditions, the file address of the instruc-
tion is not interpreted as the lower byte of an address
(used with the BSR in direct addressing), or as an 8-bit
address in the Access Bank. Instead, the value is
interpreted as an offset value to an address pointer,
specified by FSR2. The offset and the contents of
FSR2 are added to obtain the target address of the
operation.
On the other hand, using the virtual registers to write to
an FSR pair may not occur as planned. In these cases,
the value will be written to the FSR pair but without any
incrementing or decrementing. Thus, writing to INDF2
or POSTDEC2 will write the same value to the
FSR2H:FSR2L.
Since the FSRs are physical registers mapped in the
SFR space, they can be manipulated through all direct
operations. Users should proceed cautiously when
working on these registers, particularly if their code
uses indirect addressing.
5.5.2
INSTRUCTIONS AFFECTED BY
INDEXED LITERAL OFFSET MODE
Any of the core PIC18 instructions that can use direct
addressing are potentially affected by the Indexed
Literal Offset Addressing mode. This includes all
byte-oriented and bit-oriented instructions, or almost
one-half of the standard PIC18 instruction set.
Instructions that only use Inherent or Literal Addressing
modes are unaffected.
Similarly, operations by indirect addressing are gener-
ally permitted on all other SFRs. Users should exercise
the appropriate caution that they do not inadvertently
change settings that might affect the operation of the
device.
Additionally, byte-oriented and bit-oriented instructions
are not affected if they do not use the Access Bank
(Access RAM bit is ‘1’), or include a file address of 60h
or above. Instructions meeting these criteria will
continue to execute as before. A comparison of the dif-
ferent possible addressing modes when the extended
instruction set is enabled in shown in Figure 5-9.
5.5
Data Memory and the Extended
Instruction Set
Enabling the PIC18 extended instruction set (XINST
configuration bit = 1) significantly changes certain
aspects of data memory and its addressing. Specifi-
cally, the use of the Access Bank for many of the core
PIC18 instructions is different; this is due to the intro-
duction of a new addressing mode for the data memory
space.
Those who desire to use byte-oriented or bit-oriented
instructions in the Indexed Literal Offset mode should
note the changes to assembler syntax for this mode.
This is described in more detail in Section 24.2.1
“Extended Instruction Syntax”.
What does not change is just as important. The size of
the data memory space is unchanged, as well as its
linear addressing. The SFR map remains the same.
Core PIC18 instructions can still operate in both Direct
and Indirect Addressing mode; inherent and literal
instructions do not change at all. Indirect addressing
with FSR0 and FSR1 also remain unchanged.
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FIGURE 5-9:
COMPARING ADDRESSING OPTIONS FOR BIT-ORIENTED AND
BYTE-ORIENTED INSTRUCTIONS (EXTENDED INSTRUCTION SET ENABLED)
EXAMPLE INSTRUCTION: ADDWF, f, d, a (Opcode: 0010 01da ffff ffff)
000h
When ‘a’ = 0 and f ≥ 60h:
The instruction executes in
Direct Forced mode. ‘f’ is inter-
060h
080h
Bank 0
preted as a location in the
Access RAM between 060h
and 0FFh. This is the same as
locations 060h to 07Fh
(Bank 0) and F80h to FFFh
(Bank 15) of data memory.
100h
00h
Bank 1
through
Bank 14
60h
80h
Valid range
for ‘f’
FFh
Access RAM
F00h
Locations below 60h are not
available in this addressing
mode.
Bank 15
SFRs
F80h
FFFh
Data Memory
When ‘a’ = 0 and f ≤ 5Fh:
000h
080h
100h
Bank 0
The instruction executes in
Indexed Literal Offset mode. ‘f’
is interpreted as an offset to the
address value in FSR2. The
two are added together to
obtain the address of the target
register for the instruction. The
address can be anywhere in
the data memory space.
001001da ffffffff
Bank 1
through
Bank 14
FSR2H
FSR2L
F00h
F80h
Note that in this mode, the
correct syntax is now:
ADDWF [k], d
Bank 15
SFRs
where ‘k’ is the same as ‘f’.
FFFh
Data Memory
BSR
000h
080h
100h
00000000
When ‘a’ = 1 (all values of f):
Bank 0
The instruction executes in
Direct mode (also known as
Direct Long mode). ‘f’ is inter-
preted as a location in one of
the 16 banks of the data
memory space. The bank is
designated by the Bank Select
Register (BSR). The address
can be in any implemented
bank in the data memory
space.
001001da ffffffff
Bank 1
through
Bank 14
F00h
F80h
Bank 15
SFRs
FFFh
Data Memory
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Remapping of the Access Bank applies only to opera-
tions using the Indexed Literal Offset mode. Operations
that use the BSR (Access RAM bit is ‘1’) will continue
to use direct addressing as before.
5.5.3
MAPPING THE ACCESS BANK IN
INDEXED LITERAL OFFSET MODE
The use of Indexed Literal Offset Addressing mode
effectively changes how the first 96 locations of Access
RAM (00h to 5Fh) are mapped. Rather than containing
just the contents of the bottom half of Bank 0, this mode
maps the contents from Bank 0 and a user defined
“window” that can be located anywhere in the data
memory space. The value of FSR2 establishes the
lower boundary of the addresses mapped into the
window, while the upper boundary is defined by FSR2
plus 95 (5Fh). Addresses in the Access RAM above
5Fh are mapped as previously described (see
Section 5.3.2 “Access Bank”). An example of Access
Bank remapping in this addressing mode is shown in
Figure 5-10.
5.6
PIC18 Instruction Execution and
the Extended Instruction Set
Enabling the extended instruction set adds eight
additional commands to the existing PIC18 instruction
set. These instructions are executed as described in
Section 24.2 “Extended Instruction Set”.
FIGURE 5-10:
REMAPPING THE ACCESS BANK WITH INDEXED LITERAL OFFSET
ADDRESSING
Example Situation:
000h
05Fh
07Fh
ADDWF f, d, a
Bank 0
Bank 0
FSR2H:FSR2L = 120h
Locations in the region
from the FSR2 pointer
(120h) to the pointer plus
05Fh (17Fh) are mapped
to the bottom of the
Access RAM (000h-05Fh).
100h
120h
17Fh
Bank 1
Window
00h
Bank 1
Bank 1 “Window”
200h
5Fh
Locations in Bank 0 from
060h to 07Fh are mapped,
as usual, to the middle half
of the Access Bank.
Bank 0
7Fh
80h
Bank 2
through
Bank 14
SFRs
Special File Registers at
F80h through FFFh are
mapped to 80h through
FFh, as usual.
FFh
Access Bank
F00h
Bank 15
SFRs
Bank 0 addresses below
5Fh can still be addressed
by using the BSR.
F80h
FFFh
Data Memory
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6.1
Table Reads and Table Writes
6.0
FLASH PROGRAM MEMORY
In order to read and write program memory, there are
two operations that allow the processor to move bytes
between the program memory space and the data RAM:
The Flash program memory is readable, writable and
erasable during normal operation over the entire VDD
range.
• Table Read (TBLRD)
• Table Write (TBLWT)
A read from program memory is executed on one byte
at a time. A write to program memory is executed on
blocks of 64 bytes at a time. Program memory is
erased in blocks of 64 bytes at a time. A bulk erase
operation may not be issued from user code.
The program memory space is 16 bits wide, while the
data RAM space is 8 bits wide. Table reads and table
writes move data between these two memory spaces
through an 8-bit register (TABLAT).
Writing or erasing program memory will cease
instruction fetches until the operation is complete. The
program memory cannot be accessed during the write
or erase, therefore, code cannot execute. An internal
programming timer terminates program memory writes
and erases.
Table read operations retrieve data from program
memory and places it into the data RAM space.
Figure 6-1 shows the operation of a table read with
program memory and data RAM.
Table write operations store data from the data memory
space into holding registers in program memory. The
procedure to write the contents of the holding registers
into program memory is detailed in Section 6.5 “Writing
to Flash Program Memory”. Figure 6-2 shows the
operation of a table write with program memory and data
RAM.
A value written to program memory does not need to be
a valid instruction. Executing a program memory
location that forms an invalid instruction results in a
NOP.
Table operations work with byte entities. A table block
containing data, rather than program instructions, is not
required to be word aligned. Therefore, a table block can
start and end at any byte address. If a table write is being
used to write executable code into program memory,
program instructions will need to be word aligned.
FIGURE 6-1:
TABLE READ OPERATION
Instruction: TBLRD*
Program Memory
(1)
Table Pointer
Table Latch (8-bit)
TABLAT
TBLPTRU TBLPTRH TBLPTRL
Program Memory
(TBLPTR)
Note 1: Table Pointer register points to a byte in program memory.
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FIGURE 6-2:
TABLE WRITE OPERATION
Instruction: TBLWT*
Program Memory
Holding Registers
(1)
Table Pointer
Table Latch (8-bit)
TABLAT
TBLPTRU TBLPTRH TBLPTRL
Program Memory
(TBLPTR)
Note 1: Table Pointer actually points to one of 64 holding registers, the address of which is determined by
TBLPTRL<5:0>. The process for physically writing data to the program memory array is discussed in
Section 6.5 “Writing to Flash Program Memory”.
The FREE bit, when set, will allow a program memory
erase operation. When FREE is set, the erase
operation is initiated on the next WR command. When
FREE is clear, only writes are enabled.
6.2
Control Registers
Several control registers are used in conjunction with
the TBLRDand TBLWTinstructions. These include the:
• EECON1 register
• EECON2 register
• TABLAT register
• TBLPTR registers
The WREN bit, when set, will allow a write operation.
On power-up, the WREN bit is clear. The WRERR bit is
set in hardware when the WR bit is set and cleared
when the internal programming timer expires and the
write operation is complete.
6.2.1
EECON1 AND EECON2 REGISTERS
Note:
During normal operation, the WRERR is
read as ‘1’. This can indicate that a write
operation was prematurely terminated by
The EECON1 register (Register 6-1) is the control
register for memory accesses. The EECON2 register is
not a physical register; it is used exclusively in the
memory write and erase sequences. Reading
EECON2 will read all ‘0’s.
a
Reset, or
a write operation was
attempted improperly.
The WR control bit initiates write operations. The bit
cannot be cleared, only set, in software; it is cleared in
hardware at the completion of the write operation.
The EEPGD control bit determines if the access will be
a program or data EEPROM memory access. When
clear, any subsequent operations will operate on the
data EEPROM memory. When set, any subsequent
operations will operate on the program memory.
Note:
The EEIF interrupt flag bit (PIR2<4>) is set
when the write is complete. It must be
cleared in software.
The CFGS control bit determines if the access will be
to the configuration/calibration registers or to program
memory/data EEPROM memory. When set,
subsequent operations will operate on configuration
registers regardless of EEPGD (see Section 23.0
“Special Features of the CPU”). When clear, memory
selection access is determined by EEPGD.
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REGISTER 6-1:
EECON1 REGISTER
R/W-x
R/W-x
CFGS
U-0
—
R/W-0
FREE
R/W-x
R/W-0
WREN
R/S-0
WR
R/S-0
RD
EEPGD
WRERR
bit 7
bit 0
bit 7
bit 6
EEPGD: Flash Program or Data EEPROM Memory Select bit
1= Access Flash program memory
0= Access data EEPROM memory
CFGS: Flash Program/Data EEPROM or Configuration Select bit
1= Access Configuration registers
0= Access Flash program or data EEPROM memory
bit 5
bit 4
Unimplemented: Read as ‘0’
FREE: Flash Row Erase Enable bit
1= Erase the program memory row addressed by TBLPTR on the next WR command
(cleared by completion of erase operation)
0= Perform write only
bit 3
WRERR: Flash Program/Data EEPROM Error Flag bit
1= A write operation is prematurely terminated (any Reset during self-timed programming in
normal operation, or an improper write attempt)
0= The write operation completed
Note:
When a WRERR occurs, the EEPGD and CFGS bits are not cleared.
This allows tracing of the error condition.
bit 2
bit 1
WREN: Flash Program/Data EEPROM Write Enable bit
1= Allows write cycles to Flash program/data EEPROM
0= Inhibits write cycles to Flash program/data EEPROM
WR: Write Control bit
1= Initiates a data EEPROM erase/write cycle or a program memory erase cycle or write cycle.
(The operation is self-timed and the bit is cleared by hardware once write is complete.
The WR bit can only be set (not cleared) in software.)
0= Write cycle to the EEPROM is complete
bit 0
RD: Read Control bit
1= Initiates an EEPROM read (Read takes one cycle. RD is cleared in hardware. The RD bit can
only be set (not cleared) in software. RD bit cannot be set when EEPGD = 1or CFGS = 1.)
0= Does not initiate an EEPROM read
Legend:
R = Readable bit
W = Writable bit
S = Bit can be set by software, but not cleared U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
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6.2.2
TABLAT – TABLE LATCH REGISTER
6.2.4
TABLE POINTER BOUNDARIES
The Table Latch (TABLAT) is an 8-bit register mapped
into the SFR space. The Table Latch register is used to
hold 8-bit data during data transfers between program
memory and data RAM.
TBLPTR is used in reads, writes and erases of the
Flash program memory.
When a TBLRDis executed, all 22 bits of the TBLPTR
determine which byte is read from program memory
into TABLAT.
6.2.3
TBLPTR – TABLE POINTER
REGISTER
When a TBLWTis executed, the six LSbs of the Table
Pointer register (TBLPTR<5:0>) determine which of the
64 program memory holding registers is written to.
When the timed write to program memory begins (via
the WR bit), the 16 MSbs of the TBLPTR
(TBLPTR<21:6>) determine which program memory
block of 64 bytes is written to. For more detail, see
Section 6.5 “Writing to Flash Program Memory”.
The Table Pointer (TBLPTR) register addresses a byte
within the program memory. The TBLPTR is comprised
of three SFR registers: Table Pointer Upper Byte, Table
Pointer High Byte and Table Pointer Low Byte
(TBLPTRU:TBLPTRH:TBLPTRL). These three regis-
ters join to form a 22-bit wide pointer. The low-order
21 bits allow the device to address up to 2 Mbytes of
program memory space. The 22nd bit allows access to
the device ID, the user ID and the configuration bits.
When an erase of program memory is executed, the
16 MSbs of the Table Pointer register (TBLPTR<21:6>)
point to the 64-byte block that will be erased. The Least
Significant bits (TBLPTR<5:0>) are ignored.
The Table Pointer register, TBLPTR, is used by the
TBLRDand TBLWTinstructions. These instructions can
update the TBLPTR in one of four ways based on the
table operation. These operations are shown in
Table 6-1. These operations on the TBLPTR only affect
the low-order 21 bits.
Figure 6-3 describes the relevant boundaries of
TBLPTR based on Flash program memory operations.
TABLE 6-1:
Example
TABLE POINTER OPERATIONS WITH TBLRD AND TBLWT INSTRUCTIONS
Operation on Table Pointer
TBLRD*
TBLWT*
TBLPTR is not modified
TBLRD*+
TBLWT*+
TBLPTR is incremented after the read/write
TBLPTR is decremented after the read/write
TBLPTR is incremented before the read/write
TBLRD*-
TBLWT*-
TBLRD+*
TBLWT+*
FIGURE 6-3:
TABLE POINTER BOUNDARIES BASED ON OPERATION
21
16 15
TBLPTRH
8
7
TBLPTRL
0
TBLPTRU
TABLE ERASE/WRITE
TBLPTR<21:6>
TABLE WRITE
TBLPTR<5:0>
TABLE READ – TBLPTR<21:0>
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TBLPTR points to a byte address in program space.
Executing TBLRD places the byte pointed to into
TABLAT. In addition, TBLPTR can be modified
6.3
Reading the Flash Program
Memory
The TBLRD instruction is used to retrieve data from
program memory and places it into data RAM. Table
reads from program memory are performed one byte at
a time.
automatically for the next table read operation.
The internal program memory is typically organized by
words. The Least Significant bit of the address selects
between the high and low bytes of the word. Figure 6-4
shows the interface between the internal program
memory and the TABLAT.
FIGURE 6-4:
READS FROM FLASH PROGRAM MEMORY
Program Memory
(Even Byte Address)
(Odd Byte Address)
TBLPTR = xxxxx1
TBLPTR = xxxxx0
Instruction Register
(IR)
TABLAT
Read Register
FETCH
TBLRD
EXAMPLE 6-1:
READING A FLASH PROGRAM MEMORY WORD
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
; Load TBLPTR with the base
; address of the word
READ_WORD
TBLRD*+
MOVF
MOVWF
TBLRD*+
MOVFW
MOVF
; read into TABLAT and increment
; get data
TABLAT, W
WORD_EVEN
; read into TABLAT and increment
; get data
TABLAT, W
WORD_ODD
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6.4.1
FLASH PROGRAM MEMORY
ERASE SEQUENCE
6.4
Erasing Flash Program Memory
The minimum erase block is 32 words or 64 bytes. Only
through the use of an external programmer, or through
ICSP control, can larger blocks of program memory be
bulk erased. Word erase in the Flash array is not
supported.
The sequence of events for erasing a block of internal
program memory location is:
1. Load Table Pointer register with address of row
being erased.
When initiating an erase sequence from the micro-
controller itself, a block of 64 bytes of program memory
is erased. The Most Significant 16 bits of the
TBLPTR<21:6> point to the block being erased.
TBLPTR<5:0> are ignored.
2. Set the EECON1 register for the erase operation:
• set EEPGD bit to point to program memory;
• clear the CFGS bit to access program memory;
• set WREN bit to enable writes;
• set FREE bit to enable the erase.
3. Disable interrupts.
The EECON1 register commands the erase operation.
The EEPGD bit must be set to point to the Flash pro-
gram memory. The WREN bit must be set to enable
write operations. The FREE bit is set to select an erase
operation.
4. Write 55h to EECON2.
5. Write 0AAh to EECON2.
6. Set the WR bit. This will begin the row erase
cycle.
For protection, the write initiate sequence for EECON2
must be used.
7. The CPU will stall for duration of the erase
(about 2 ms using internal timer).
A long write is necessary for erasing the internal Flash.
Instruction execution is halted while in a long write
cycle. The long write will be terminated by the internal
programming timer.
8. Re-enable interrupts.
EXAMPLE 6-2:
ERASING A FLASH PROGRAM MEMORY ROW
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
; load TBLPTR with the base
; address of the memory block
ERASE_ROW
BSF
BCF
BSF
BSF
EECON1, EEPGD
EECON1, CFGS
EECON1, WREN
EECON1, FREE
INTCON, GIE
55h
EECON2
0AAh
EECON2
EECON1, WR
INTCON, GIE
; point to Flash program memory
; access Flash program memory
; enable write to memory
; enable Row Erase operation
; disable interrupts
BCF
Required
Sequence
MOVLW
MOVWF
MOVLW
MOVWF
BSF
; write 55h
; write 0AAh
; start erase (CPU stall)
; re-enable interrupts
BSF
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The long write is necessary for programming the inter-
6.5
Writing to Flash Program Memory
nal Flash. Instruction execution is halted while in a long
write cycle. The long write will be terminated by the
internal programming timer.
The minimum programming block is 32 words or
64 bytes. Word or byte programming is not supported.
Table writes are used internally to load the holding
registers needed to program the Flash memory. There
are 64 holding registers used by the table writes for
programming.
The EEPROM on-chip timer controls the write time.
The write/erase voltages are generated by an on-chip
charge pump, rated to operate over the voltage range
of the device.
Since the Table Latch (TABLAT) is only a single byte,
the TBLWT instruction may need to be executed 64
times for each programming operation. All of the table
write operations will essentially be short writes because
only the holding registers are written. At the end of
updating the 64 holding registers, the EECON1 register
must be written to in order to start the programming
operation with a long write.
Note:
The default value of the holding registers on
device Resets and after write operations is
FFh. A write of FFh to a holding register
does not modify that byte. This means that
individual bytes of program memory may be
modified, provided that the change does not
attempt to change any bit from a ‘0’ to a ‘1’.
When modifying individual bytes, it is not
necessary to load all 64 holding registers
before executing a write operation.
FIGURE 6-5:
TABLE WRITES TO FLASH PROGRAM MEMORY
TABLAT
Write Register
8
8
8
8
TBLPTR = xxxxx0
TBLPTR = xxxxx1
TBLPTR = xxxxx2
TBLPTR = xxxx3F
Holding Register
Holding Register
Holding Register
Holding Register
Program Memory
8. Disable interrupts.
6.5.1
FLASH PROGRAM MEMORY WRITE
SEQUENCE
9. Write 55h to EECON2.
10. Write 0AAh to EECON2.
The sequence of events for programming an internal
program memory location should be:
11. Set the WR bit. This will begin the write cycle.
12. The CPU will stall for duration of the write (about
2 ms using internal timer).
1. Read 64 bytes into RAM.
2. Update data values in RAM as necessary.
13. Re-enable interrupts.
3. Load Table Pointer register with address being
erased.
14. Verify the memory (table read).
This procedure will require about 6 ms to update one
row of 64 bytes of memory. An example of the required
code is given in Example 6-3.
4. Execute the row erase procedure.
5. Load Table Pointer register with address of first
byte being written.
6. Write the 64 bytes into the holding registers with
auto-increment.
Note:
Before setting the WR bit, the Table
Pointer address needs to be within the
intended address range of the 64 bytes in
the holding register.
7. Set the EECON1 register for the write operation:
• set EEPGD bit to point to program memory;
• clear the CFGS bit to access program memory;
• set WREN to enable byte writes.
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EXAMPLE 6-3:
WRITING TO FLASH PROGRAM MEMORY
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
D'64
COUNTER
BUFFER_ADDR_HIGH
FSR0H
BUFFER_ADDR_LOW
FSR0L
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
; number of bytes in erase block
; point to buffer
; Load TBLPTR with the base
; address of the memory block
READ_BLOCK
TBLRD*+
MOVF
MOVWF
DECFSZ
BRA
; read into TABLAT, and inc
; get data
; store data
; done?
TABLAT, W
POSTINC0
COUNTER
READ_BLOCK
; repeat
MODIFY_WORD
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
DATA_ADDR_HIGH
FSR0H
DATA_ADDR_LOW
FSR0L
NEW_DATA_LOW
POSTINC0
NEW_DATA_HIGH
INDF0
; point to buffer
; update buffer word
ERASE_BLOCK
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BCF
BSF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
EECON1, EEPGD
EECON1, CFGS
EECON1, WREN
EECON1, FREE
INTCON, GIE
55h
EECON2
0AAh
EECON2
EECON1, WR
INTCON, GIE
; load TBLPTR with the base
; address of the memory block
; point to Flash program memory
; access Flash program memory
; enable write to memory
; enable Row Erase operation
; disable interrupts
Required
Sequence
; write 55h
; write 0AAh
; start erase (CPU stall)
; re-enable interrupts
; dummy read decrement
; point to buffer
BSF
TBLRD*-
MOVLW
MOVWF
MOVLW
MOVWF
BUFFER_ADDR_HIGH
FSR0H
BUFFER_ADDR_LOW
FSR0L
WRITE_BUFFER_BACK
MOVLW
MOVWF
D’64
COUNTER
; number of bytes in holding register
WRITE_BYTE_TO_HREGS
MOVFF
MOVWF
TBLWT+*
POSTINC0, WREG
TABLAT
; get low byte of buffer data
; present data to table latch
; write data, perform a short write
; to internal TBLWT holding register.
; loop until buffers are full
DECFSZ
BRA
COUNTER
WRITE_WORD_TO_HREGS
DS39631A-page 80
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EXAMPLE 6-3:
WRITING TO FLASH PROGRAM MEMORY (CONTINUED)
PROGRAM_MEMORY
BSF
BCF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
EECON1, EEPGD
EECON1, CFGS
EECON1, WREN
INTCON, GIE
55h
EECON2
0AAh
EECON2
; point to Flash program memory
; access Flash program memory
; enable write to memory
; disable interrupts
Required
Sequence
; write 55h
; write 0AAh
EECON1, WR
INTCON, GIE
EECON1, WREN
; start program (CPU stall)
; re-enable interrupts
; disable write to memory
BSF
BCF
6.5.2
WRITE VERIFY
6.5.4
PROTECTION AGAINST
SPURIOUS WRITES
Depending on the application, good programming
practice may dictate that the value written to the
memory should be verified against the original value.
This should be used in applications where excessive
writes can stress bits near the specification limit.
To protect against spurious writes to Flash program
memory, the write initiate sequence must also be
followed. See Section 23.0 “Special Features of the
CPU” for more detail.
6.5.3
UNEXPECTED TERMINATION OF
WRITE OPERATION
6.6
Flash Program Operation During
Code Protection
If a write is terminated by an unplanned event, such as
loss of power or an unexpected Reset, the memory
location just programmed should be verified and repro-
grammed if needed. If the write operation is interrupted
by a MCLR Reset or a WDT Time-out Reset during
normal operation, the user can check the WRERR bit
and rewrite the location(s) as needed.
See Section 23.5 “Program Verification and Code
Protection” for details on code protection of Flash
program memory.
TABLE 6-2:
Name
REGISTERS ASSOCIATED WITH PROGRAM FLASH MEMORY
Reset
Valueson
page
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TBLPTRU
—
—
bit 21 Program Memory Table Pointer Upper Byte (TBLPTR<20:16>)
49
49
49
49
49
51
51
52
52
52
TBPLTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>)
TBLPTRL Program Memory Table Pointer Low Byte (TBLPTR<7:0>)
TABLAT
INTCON
Program Memory Table Latch
GIE/GIEH PEIE/GIEL TMR0IE INT0IE
RBIE
TMR0IF
INT0IF
RBIF
EECON2 EEPROM Control Register 2 (not a physical register)
EECON1
IPR2
EEPGD
OSCFIP
OSCFIF
OSCFIE
CFGS
CMIP
CMIF
CMIE
—
—
—
—
FREE
EEIP
EEIF
EEIE
WRERR
BCLIP
BCLIF
BCLIE
WREN
HLVDIP
HLVDIF
HLVDIE
WR
RD
TMR3IP
TMR3IF
TMR3IE
CCP2IP
CCP2IF
CCP2IE
PIR2
PIE2
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
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NOTES:
DS39631A-page 82
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The EECON1 register (Register 7-1) is the control reg-
ister for data and program memory access. Control bit
EEPGD determines if the access will be to program or
data EEPROM memory. When clear, operations will
access the data EEPROM memory. When set, program
memory is accessed.
7.0
DATA EEPROM MEMORY
The data EEPROM is a nonvolatile memory array, sep-
arate from the data RAM and program memory, that is
used for long-term storage of program data. It is not
directly mapped in either the register file or program
memory space but is indirectly addressed through the
Special Function Registers (SFRs). The EEPROM is
readable and writable during normal operation over the
entire VDD range.
Control bit, CFGS, determines if the access will be to
the configuration registers or to program memory/data
EEPROM memory. When set, subsequent operations
access configuration registers. When CFGS is clear,
the EEPGD bit selects either program Flash or data
EEPROM memory.
Five SFRs are used to read and write to the data
EEPROM as well as the program memory. They are:
• EECON1
• EECON2
• EEDATA
• EEADR
The WREN bit, when set, will allow a write operation.
On power-up, the WREN bit is clear. The WRERR bit is
set in hardware when the WR bit is set and cleared
when the internal programming timer expires and the
write operation is complete.
The data EEPROM allows byte read and write. When
interfacing to the data memory block, EEDATA holds
the 8-bit data for read/write and the EEADR register
holds the address of the EEPROM location being
accessed.
Note:
During normal operation, the WRERR
may read as ‘1’. This can indicate that a
write operation was prematurely termi-
nated by a Reset, or a write operation was
attempted improperly.
The EEPROM data memory is rated for high erase/write
cycle endurance. A byte write automatically erases the
location and writes the new data (erase-before-write).
The write time is controlled by an on-chip timer; it will
vary with voltage and temperature as well as from chip
to chip. Please refer to parameter D122 (Table 26-1 in
Section 26.0 “Electrical Characteristics”) for exact
limits.
The WR control bit initiates write operations. The bit
can be set but not cleared in software. It is only cleared
in hardware at the completion of the write operation.
Note:
The EEIF interrupt flag bit (PIR2<4>) is set
when the write is complete. It must be
cleared in software.
Control bits, RD and WR, start read and erase/write
operations, respectively. These bits are set by firmware
and cleared by hardware at the completion of the
operation.
7.1
EEADR Register
The EEADR register is used to address the data
EEPROM for read and write operations. The 8-bit
range of the register can address a memory range of
256 bytes (00h to FFh).
The RD bit cannot be set when accessing program
memory (EEPGD = 1). Program memory is read using
table read instructions. See Section 6.1 “Table Reads
and Table Writes” regarding table reads.
7.2
EECON1 and EECON2 Registers
The EECON2 register is not a physical register. It is
used exclusively in the memory write and erase
sequences. Reading EECON2 will read all ‘0’s.
Access to the data EEPROM is controlled by two
registers: EECON1 and EECON2. These are the same
registers which control access to the program memory
and are used in a similar manner for the data
EEPROM.
2004 Microchip Technology Inc.
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REGISTER 7-1:
EECON1 REGISTER
R/W-x
R/W-x
CFGS
U-0
—
R/W-0
FREE
R/W-x
R/W-0
WREN
R/S-0
WR
R/S-0
RD
EEPGD
WRERR
bit 7
bit 0
bit 7
bit 6
EEPGD: Flash Program or Data EEPROM Memory Select bit
1= Access Flash program memory
0= Access data EEPROM memory
CFGS: Flash Program/Data EEPROM or Configuration Select bit
1= Access configuration registers
0= Access Flash program or data EEPROM memory
bit 5
bit 4
Unimplemented: Read as ‘0’
FREE: Flash Row Erase Enable bit
1= Erase the program memory row addressed by TBLPTR on the next WR command
(cleared by completion of erase operation)
0= Perform write only
bit 3
WRERR: Flash Program/Data EEPROM Error Flag bit
1= A write operation is prematurely terminated (any Reset during self-timed programming in
normal operation, or an improper write attempt)
0= The write operation completed
Note:
When a WRERR occurs, the EEPGD and CFGS bits are not cleared.
This allows tracing of the error condition.
bit 2
bit 1
WREN: Flash Program/Data EEPROM Write Enable bit
1= Allows write cycles to Flash program/data EEPROM
0= Inhibits write cycles to Flash program/data EEPROM
WR: Write Control bit
1= Initiates a data EEPROM erase/write cycle or a program memory erase cycle or write cycle
(The operation is self-timed and the bit is cleared by hardware once write is complete.
The WR bit can only be set (not cleared) in software.)
0= Write cycle to the EEPROM is complete
bit 0
RD: Read Control bit
1= Initiates an EEPROM read (Read takes one cycle. RD is cleared in hardware. The RD bit can
only be set (not cleared) in software. RD bit cannot be set when EEPGD = 1or CFGS = 1.)
0= Does not initiate an EEPROM read
Legend:
R = Readable bit
W = Writable bit
S = Bit can be set by software, but not cleared U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
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Additionally, the WREN bit in EECON1 must be set to
enable writes. This mechanism prevents accidental
writes to data EEPROM due to unexpected code exe-
7.3
Reading the Data EEPROM
Memory
To read a data memory location, the user must write the
address to the EEADR register, clear the EEPGD con-
trol bit (EECON1<7>) and then set control bit, RD
(EECON1<0>). The data is available on the very next
instruction cycle; therefore, the EEDATA register can
be read by the next instruction. EEDATA will hold this
value until another read operation, or until it is written to
by the user (during a write operation).
cution (i.e., runaway programs). The WREN bit should
be kept clear at all times, except when updating the
EEPROM. The WREN bit is not cleared by hardware.
After a write sequence has been initiated, EECON1,
EEADR and EEDATA cannot be modified. The WR bit
will be inhibited from being set unless the WREN bit is
set. Both WR and WREN cannot be set with the same
instruction.
The basic process is shown in Example 7-1.
At the completion of the write cycle, the WR bit is
cleared in hardware and the EEPROM Interrupt Flag
bit, EEIF, is set. The user may either enable this
interrupt or poll this bit. EEIF must be cleared by
software.
7.4
Writing to the Data EEPROM
Memory
To write an EEPROM data location, the address must
first be written to the EEADR register and the data writ-
ten to the EEDATA register. The sequence in
Example 7-2 must be followed to initiate the write cycle.
7.5
Write Verify
Depending on the application, good programming
practice may dictate that the value written to the
memory should be verified against the original value.
This should be used in applications where excessive
writes can stress bits near the specification limit.
The write will not begin if this sequence is not exactly
followed (write 55h to EECON2, write 0AAh to
EECON2, then set WR bit) for each byte. It is strongly
recommended that interrupts be disabled during this
code segment.
EXAMPLE 7-1:
DATA EEPROM READ
MOVLW
MOVWF
BCF
DATA_EE_ADDR
EEADR
EECON1, EEPGD ; Point to DATA memory
;
; Data Memory Address to read
BCF
BSF
MOVF
EECON1, CFGS
EECON1, RD
EEDATA, W
; Access EEPROM
; EEPROM Read
; W = EEDATA
EXAMPLE 7-2:
DATA EEPROM WRITE
MOVLW
MOVWF
MOVLW
MOVWF
BCF
DATA_EE_ADDR
EEADR
;
; Data Memory Address to write
;
; Data Memory Value to write
; Point to DATA memory
; Access EEPROM
DATA_EE_DATA
EEDATA
EECON1, EEPGD
EECON1, CFGS
EECON1, WREN
BCF
BSF
; Enable writes
BCF
INTCON, GIE
55h
EECON2
0AAh
EECON2
; Disable Interrupts
;
; Write 55h
;
; Write 0AAh
; Set WR bit to begin write
; Enable Interrupts
MOVLW
MOVWF
MOVLW
MOVWF
BSF
Required
Sequence
EECON1, WR
INTCON, GIE
BSF
; User code execution
BCF
EECON1, WREN
; Disable writes on write complete (EEIF set)
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7.6
Operation During Code-Protect
7.8
Using the Data EEPROM
Data EEPROM memory has its own code-protect bits in
configuration words. External read and write
operations are disabled if code protection is enabled.
The data EEPROM is a high endurance, byte
addressable array that has been optimized for the
storage of frequently changing information (e.g.,
program variables or other data that are updated
often). Frequently changing values will typically be
updated more often than specification D124. If this is
not the case, an array refresh must be performed. For
this reason, variables that change infrequently (such as
constants, IDs, calibration, etc.) should be stored in
Flash program memory.
The microcontroller itself can both read and write to the
internal data EEPROM, regardless of the state of the
code-protect configuration bit. Refer to Section 23.0
“Special Features of the CPU” for additional
information.
7.7
Protection Against Spurious Write
A simple data EEPROM refresh routine is shown in
Example 7-3.
There are conditions when the user may not want to
write to the data EEPROM memory. To protect against
spurious EEPROM writes, various mechanisms have
been implemented. On power-up, the WREN bit is
cleared. In addition, writes to the EEPROM are blocked
during the Power-up Timer period (TPWRT,
parameter 33).
Note:
If data EEPROM is only used to store
constants and/or data that changes rarely,
an array refresh is likely not required. See
specification D124.
The write initiate sequence and the WREN bit together
help prevent an accidental write during brown-out,
power glitch or software malfunction.
EXAMPLE 7-3:
DATA EEPROM REFRESH ROUTINE
CLRF
BCF
BCF
BCF
BSF
EEADR
; Start at address 0
; Set for memory
; Set for Data EEPROM
; Disable interrupts
; Enable writes
; Loop to refresh array
; Read current address
;
; Write 55h
;
; Write 0AAh
; Set WR bit to begin write
; Wait for write to complete
EECON1, CFGS
EECON1, EEPGD
INTCON, GIE
EECON1, WREN
Loop
BSF
EECON1, RD
55h
EECON2
0AAh
EECON2
EECON1, WR
EECON1, WR
$-2
MOVLW
MOVWF
MOVLW
MOVWF
BSF
BTFSC
BRA
INCFSZ
BRA
EEADR, F
LOOP
; Increment address
; Not zero, do it again
BCF
BSF
EECON1, WREN
INTCON, GIE
; Disable writes
; Enable interrupts
DS39631A-page 86
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TABLE 7-1:
Name
REGISTERS ASSOCIATED WITH DATA EEPROM MEMORY
Reset
Values
on page
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
EEADR
EEDATA
EECON2
EECON1
IPR2
GIE/GIEH PEIE/GIEL TMR0IE
EEPROM Address Register
EEPROM Data Register
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
49
51
51
51
51
52
52
52
EEPROM Control Register 2 (not a physical register)
EEPGD
OSCFIP
OSCFIF
OSCFIE
CFGS
CMIP
CMIF
CMIE
—
—
—
—
FREE
EEIP
EEIF
EEIE
WRERR
BCLIP
BCLIF
BCLIE
WREN
WR
RD
HLVDIP TMR3IP CCP2IP
HLVDIF TMR3IF CCP2IF
HLVDIE TMR3IE CCP2IE
PIR2
PIE2
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
2004 Microchip Technology Inc.
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NOTES:
DS39631A-page 88
Preliminary
2004 Microchip Technology Inc.
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EXAMPLE 8-1:
8 x 8 UNSIGNED
MULTIPLY ROUTINE
8.0
8.1
8 x 8 HARDWARE MULTIPLIER
Introduction
MOVF
MULWF
ARG1, W
ARG2
;
; ARG1 * ARG2 ->
; PRODH:PRODL
All PIC18 devices include an 8 x 8 hardware multiplier
as part of the ALU. The multiplier performs an unsigned
operation and yields a 16-bit result that is stored in the
product register pair, PRODH:PRODL. The multiplier’s
operation does not affect any flags in the Status
register.
EXAMPLE 8-2:
8 x 8 SIGNED MULTIPLY
ROUTINE
Making multiplication a hardware operation allows it to
be completed in a single instruction cycle. This has the
advantages of higher computational throughput and
reduced code size for multiplication algorithms and
allows the PIC18 devices to be used in many applica-
tions previously reserved for digital signal processors.
A comparison of various hardware and software
multiply operations, along with the savings in memory
and execution time, is shown in Table 8-1.
MOVF
MULWF
ARG1, W
ARG2
; ARG1 * ARG2 ->
; PRODH:PRODL
; Test Sign Bit
; PRODH = PRODH
BTFSC
SUBWF
ARG2, SB
PRODH, F
;
- ARG1
MOVF
BTFSC
SUBWF
ARG2, W
ARG1, SB
PRODH, F
; Test Sign Bit
; PRODH = PRODH
;
- ARG2
8.2
Operation
Example 8-1 shows the instruction sequence for an 8 x 8
unsigned multiplication. Only one instruction is required
when one of the arguments is already loaded in the
WREG register.
Example 8-2 shows the sequence to do an 8 x 8 signed
multiplication. To account for the sign bits of the argu-
ments, each argument’s Most Significant bit (MSb) is
tested and the appropriate subtractions are done.
TABLE 8-1:
Routine
PERFORMANCE COMPARISON FOR VARIOUS MULTIPLY OPERATIONS
Program
Memory
(Words)
Time
Cycles
(Max)
Multiply Method
@ 40 MHz @ 10 MHz @ 4 MHz
Without hardware multiply
Hardware multiply
13
1
69
1
6.9 µs
100 ns
9.1 µs
600 ns
24.2 µs
2.8 µs
25.4 µs
4.0 µs
27.6 µs
400 ns
36.4 µs
2.4 µs
69 µs
1 µs
91 µs
6 µs
8 x 8 unsigned
8 x 8 signed
Without hardware multiply
Hardware multiply
33
6
91
6
Without hardware multiply
Hardware multiply
21
28
52
35
242
28
254
40
96.8 µs
11.2 µs
102.6 µs
16.0 µs
242 µs
28 µs
254 µs
40 µs
16 x 16 unsigned
16 x 16 signed
Without hardware multiply
Hardware multiply
2004 Microchip Technology Inc.
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Example 8-3 shows the sequence to do a 16 x 16
unsigned multiplication. Equation 8-1 shows the
algorithm that is used. The 32-bit result is stored in four
registers (RES3:RES0).
EQUATION 8-2:
16 x 16 SIGNED
MULTIPLICATION
ALGORITHM
RES3:RES0 = ARG1H:ARG1L • ARG2H:ARG2L
16
= (ARG1H • ARG2H • 2 ) +
(ARG1H • ARG2L • 2 ) +
(ARG1L • ARG2H • 2 ) +
(ARG1L • ARG2L) +
(-1 • ARG2H<7> • ARG1H:ARG1L • 2 ) +
(-1 • ARG1H<7> • ARG2H:ARG2L • 2
8
EQUATION 8-1:
16 x 16 UNSIGNED
MULTIPLICATION
ALGORITHM
8
16
RES3:RES0
=
=
ARG1H:ARG1L • ARG2H:ARG2L
16
)
16
(ARG1H • ARG2H • 2 ) +
8
(ARG1H • ARG2L • 2 ) +
8
(ARG1L • ARG2H • 2 ) +
EXAMPLE 8-4:
16 x 16 SIGNED
MULTIPLY ROUTINE
(ARG1L • ARG2L)
MOVF
MULWF
ARG1L, W
ARG2L
; ARG1L * ARG2L ->
; PRODH:PRODL
;
;
EXAMPLE 8-3:
16 x 16 UNSIGNED
MULTIPLY ROUTINE
MOVFF
MOVFF
PRODH, RES1
PRODL, RES0
MOVF
MULWF
ARG1L, W
ARG2L
; ARG1L * ARG2L->
; PRODH:PRODL
;
;
;
;
MOVF
MULWF
ARG1H, W
ARG2H
MOVFF
MOVFF
PRODH, RES1
PRODL, RES0
; ARG1H * ARG2H ->
; PRODH:PRODL
;
;
;
;
MOVFF
MOVFF
PRODH, RES3
PRODL, RES2
MOVF
MULWF
ARG1H, W
ARG2H
; ARG1H * ARG2H->
; PRODH:PRODL
;
;
MOVF
MULWF
ARG1L, W
ARG2H
MOVFF
MOVFF
PRODH, RES3
PRODL, RES2
; ARG1L * ARG2H ->
; PRODH:PRODL
;
; Add cross
; products
;
;
;
MOVF
ADDWF
MOVF
ADDWFC RES2, F
CLRF WREG
ADDWFC RES3, F
PRODL, W
RES1, F
PRODH, W
MOVF
MULWF
ARG1L, W
ARG2H
; ARG1L * ARG2H->
; PRODH:PRODL
;
; Add cross
; products
;
;
;
MOVF
ADDWF
MOVF
PRODL, W
RES1, F
PRODH, W
;
ADDWFC RES2, F
CLRF WREG
ADDWFC RES3, F
MOVF
MULWF
ARG1H, W
ARG2L
;
; ARG1H * ARG2L ->
; PRODH:PRODL
;
; Add cross
; products
;
;
;
;
MOVF
ADDWF
MOVF
ADDWFC RES2, F
CLRF WREG
ADDWFC RES3, F
PRODL, W
RES1, F
PRODH, W
MOVF
MULWF
ARG1H, W
ARG2L
;
; ARG1H * ARG2L->
; PRODH:PRODL
;
; Add cross
; products
MOVF
ADDWF
MOVF
PRODL, W
RES1, F
PRODH, W
;
;
ADDWFC RES2, F
CLRF WREG
ADDWFC RES3, F
;
;
;
BTFSS
BRA
MOVF
SUBWF
MOVF
ARG2H, 7
SIGN_ARG1
ARG1L, W
RES2
; ARG2H:ARG2L neg?
; no, check ARG1
;
;
;
Example 8-4 shows the sequence to do a 16 x 16
signed multiply. Equation 8-2 shows the algorithm
used. The 32-bit result is stored in four registers
(RES3:RES0). To account for the sign bits of the argu-
ments, the MSb for each argument pair is tested and
the appropriate subtractions are done.
ARG1H, W
SUBWFB RES3
SIGN_ARG1
BTFSS
BRA
ARG1H, 7
CONT_CODE
ARG2L, W
RES2
; ARG1H:ARG1L neg?
; no, done
;
;
;
MOVF
SUBWF
MOVF
ARG2H, W
SUBWFB RES3
;
CONT_CODE
:
DS39631A-page 90
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
When the IPEN bit is cleared (default state), the
interrupt priority feature is disabled and interrupts are
9.0
INTERRUPTS
compatible with PICmicro® mid-range devices. In Com-
patibility mode, the interrupt priority bits for each source
have no effect. INTCON<6> is the PEIE bit, which
enables/disables all peripheral interrupt sources.
INTCON<7> is the GIE bit, which enables/disables all
interrupt sources. All interrupts branch to address
0008h in Compatibility mode.
The PIC18F2420/2520/4420/4520 devices have multi-
ple interrupt sources and an interrupt priority feature
that allows most interrupt sources to be assigned a
high priority level or a low priority level. The high priority
interrupt vector is at 0008h and the low priority interrupt
vector is at 0018h. High priority interrupt events will
interrupt any low priority interrupts that may be in
progress.
When an interrupt is responded to, the global interrupt
enable bit is cleared to disable further interrupts. If the
IPEN bit is cleared, this is the GIE bit. If interrupt priority
levels are used, this will be either the GIEH or GIEL bit.
High priority interrupt sources can interrupt a low
priority interrupt. Low priority interrupts are not
processed while high priority interrupts are in progress.
There are ten registers which are used to control
interrupt operation. These registers are:
• RCON
• INTCON
• INTCON2
• INTCON3
• PIR1, PIR2
• PIE1, PIE2
• IPR1, IPR2
The return address is pushed onto the stack and the
PC is loaded with the interrupt vector address (0008h
or 0018h). Once in the Interrupt Service Routine, the
source(s) of the interrupt can be determined by polling
the interrupt flag bits. The interrupt flag bits must be
cleared in software before re-enabling interrupts to
avoid recursive interrupts.
It is recommended that the Microchip header files sup-
plied with MPLAB® IDE be used for the symbolic bit
names in these registers. This allows the assembler/
compiler to automatically take care of the placement of
these bits within the specified register.
The “return from interrupt” instruction, RETFIE, exits
the interrupt routine and sets the GIE bit (GIEH or GIEL
if priority levels are used), which re-enables interrupts.
In general, interrupt sources have three bits to control
their operation. They are:
For external interrupt events, such as the INT pins or
the PORTB input change interrupt, the interrupt latency
will be three to four instruction cycles. The exact
latency is the same for one or two-cycle instructions.
Individual interrupt flag bits are set, regardless of the
status of their corresponding enable bit or the GIE bit.
• Flag bit to indicate that an interrupt event
occurred
• Enable bit that allows program execution to
branch to the interrupt vector address when the
flag bit is set
Note:
Do not use the MOVFFinstruction to modify
any of the interrupt control registers while
any interrupt is enabled. Doing so may
cause erratic microcontroller behavior.
• Priority bit to select high priority or low priority
The interrupt priority feature is enabled by setting the
IPEN bit (RCON<7>). When interrupt priority is
enabled, there are two bits which enable interrupts
globally. Setting the GIEH bit (INTCON<7>) enables all
interrupts that have the priority bit set (high priority).
Setting the GIEL bit (INTCON<6>) enables all inter-
rupts that have the priority bit cleared (low priority).
When the interrupt flag, enable bit and appropriate
global interrupt enable bit are set, the interrupt will vec-
tor immediately to address 0008h or 0018h, depending
on the priority bit setting. Individual interrupts can be
disabled through their corresponding enable bits.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 91
PIC18F2420/2520/4420/4520
FIGURE 9-1:
PIC18 INTERRUPT LOGIC
Wake-up if in
Idle or Sleep modes
TMR0IF
TMR0IE
TMR0IP
RBIF
RBIE
RBIP
INT0IF
INT0IE
Interrupt to CPU
Vector to Location
0008h
INT1IF
INT1IE
INT1IP
INT2IF
INT2IE
INT2IP
SSPIF
SSPIE
SSPIP
GIEH/GIE
ADIF
ADIE
ADIP
IPEN
IPEN
RCIF
RCIE
RCIP
GIEL/PEIE
IPEN
Additional Peripheral Interrupts
High Priority Interrupt Generation
Low Priority Interrupt Generation
SSPIF
SSPIE
SSPIP
Interrupt to CPU
Vector to Location
0018h
TMR0IF
TMR0IE
TMR0IP
ADIF
ADIE
ADIP
RBIF
RBIE
RBIP
RCIF
RCIE
RCIP
GIEH/GIE
GIEL/PEIE
INT1IF
INT1IE
INT1IP
Additional Peripheral Interrupts
INT2IF
INT2IE
INT2IP
DS39631A-page 92
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
9.1
INTCON Registers
Note:
Interrupt flag bits are set when an interrupt
condition occurs, regardless of the state of
its corresponding enable bit or the global
enable bit. User software should ensure
the appropriate interrupt flag bits are clear
prior to enabling an interrupt. This feature
allows for software polling.
The INTCON registers are readable and writable
registers, which contain various enable, priority and
flag bits.
REGISTER 9-1:
INTCON REGISTER
R/W-0 R/W-0
R/W-0
R/W-0
INT0IE
R/W-0
RBIE
R/W-0
R/W-0
INT0IF
R/W-x
RBIF
GIE/GIEH PEIE/GIEL TMR0IE
bit 7
TMR0IF
bit 0
bit 7
GIE/GIEH: Global Interrupt Enable bit
When IPEN = 0:
1= Enables all unmasked interrupts
0= Disables all interrupts
When IPEN = 1:
1= Enables all high priority interrupts
0= Disables all interrupts
bit 6
PEIE/GIEL: Peripheral Interrupt Enable bit
When IPEN = 0:
1= Enables all unmasked peripheral interrupts
0= Disables all peripheral interrupts
When IPEN = 1:
1= Enables all low priority peripheral interrupts
0= Disables all low priority peripheral interrupts
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
TMR0IE: TMR0 Overflow Interrupt Enable bit
1= Enables the TMR0 overflow interrupt
0= Disables the TMR0 overflow interrupt
INT0IE: INT0 External Interrupt Enable bit
1= Enables the INT0 external interrupt
0= Disables the INT0 external interrupt
RBIE: RB Port Change Interrupt Enable bit
1= Enables the RB port change interrupt
0= Disables the RB port change interrupt
TMR0IF: TMR0 Overflow Interrupt Flag bit
1= TMR0 register has overflowed (must be cleared in software)
0= TMR0 register did not overflow
INT0IF: INT0 External Interrupt Flag bit
1= The INT0 external interrupt occurred (must be cleared in software)
0= The INT0 external interrupt did not occur
RBIF: RB Port Change Interrupt Flag bit
1= At least one of the RB7:RB4 pins changed state (must be cleared in software)
0= None of the RB7:RB4 pins have changed state
Note:
A mismatch condition will continue to set this bit. Reading PORTB will end the
mismatch condition and allow the bit to be cleared.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 93
PIC18F2420/2520/4420/4520
REGISTER 9-2:
INTCON2 REGISTER
R/W-1
RBPU
R/W-1
R/W-1
R/W-1
U-0
—
R/W-1
U-0
—
R/W-1
RBIP
INTEDG0 INTEDG1 INTEDG2
TMR0IP
bit 7
bit 0
bit 7
bit 6
bit 5
bit 4
RBPU: PORTB Pull-up Enable bit
1= All PORTB pull-ups are disabled
0= PORTB pull-ups are enabled by individual port latch values
INTEDG0: External Interrupt 0 Edge Select bit
1= Interrupt on rising edge
0= Interrupt on falling edge
INTEDG1: External Interrupt 1 Edge Select bit
1= Interrupt on rising edge
0= Interrupt on falling edge
INTEDG2: External Interrupt 2 Edge Select bit
1= Interrupt on rising edge
0= Interrupt on falling edge
bit 3
bit 2
Unimplemented: Read as ‘0’
TMR0IP: TMR0 Overflow Interrupt Priority bit
1= High priority
0= Low priority
bit 1
bit 0
Unimplemented: Read as ‘0’
RBIP: RB Port Change Interrupt Priority bit
1= High priority
0= Low priority
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
Note:
Interrupt flag bits are set when an interrupt condition occurs, regardless of the state
of its corresponding enable bit or the global enable bit. User software should ensure
the appropriate interrupt flag bits are clear prior to enabling an interrupt. This feature
allows for software polling.
DS39631A-page 94
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 9-3:
INTCON3 REGISTER
R/W-1
R/W-1
U-0
—
R/W-0
R/W-0
U-0
—
R/W-0
INT2IF
R/W-0
INT1IF
INT2IP
INT1IP
INT2IE
INT1IE
bit 7
bit 0
bit 7
bit 6
INT2IP: INT2 External Interrupt Priority bit
1= High priority
0= Low priority
INT1IP: INT1 External Interrupt Priority bit
1= High priority
0= Low priority
bit 5
bit 4
Unimplemented: Read as ‘0’
INT2IE: INT2 External Interrupt Enable bit
1= Enables the INT2 external interrupt
0= Disables the INT2 external interrupt
bit 3
INT1IE: INT1 External Interrupt Enable bit
1= Enables the INT1 external interrupt
0= Disables the INT1 external interrupt
bit 2
bit 1
Unimplemented: Read as ‘0’
INT2IF: INT2 External Interrupt Flag bit
1= The INT2 external interrupt occurred (must be cleared in software)
0= The INT2 external interrupt did not occur
bit 0
INT1IF: INT1 External Interrupt Flag bit
1= The INT1 external interrupt occurred (must be cleared in software)
0= The INT1 external interrupt did not occur
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
Note:
Interrupt flag bits are set when an interrupt condition occurs, regardless of the state
of its corresponding enable bit or the global enable bit. User software should ensure
the appropriate interrupt flag bits are clear prior to enabling an interrupt. This feature
allows for software polling.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 95
PIC18F2420/2520/4420/4520
9.2
PIR Registers
Note 1: Interrupt flag bits are set when an interrupt
condition occurs, regardless of the state of
its corresponding enable bit or the Global
Interrupt Enable bit, GIE (INTCON<7>).
The PIR registers contain the individual flag bits for the
peripheral interrupts. Due to the number of peripheral
interrupt sources, there are two Peripheral Interrupt
Request Flag registers (PIR1 and PIR2).
2: User software should ensure the appropri-
ate interrupt flag bits are cleared prior to
enabling an interrupt and after servicing
that interrupt.
REGISTER 9-4:
PIR1: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 1
R/W-0
PSPIF(1)
bit 7
R/W-0
ADIF
R-0
R-0
R/W-0
SSPIF
R/W-0
R/W-0
R/W-0
RCIF
TXIF
CCP1IF
TMR2IF
TMR1IF
bit 0
bit 7
PSPIF: Parallel Slave Port Read/Write Interrupt Flag bit(1)
1= A read or a write operation has taken place (must be cleared in software)
0= No read or write has occurred
Note 1: This bit is unimplemented on 28-pin devices and will read as ‘0’.
bit 6
bit 5
bit 4
bit 3
bit 2
ADIF: A/D Converter Interrupt Flag bit
1= An A/D conversion completed (must be cleared in software)
0= The A/D conversion is not complete
RCIF: EUSART Receive Interrupt Flag bit
1= The EUSART receive buffer, RCREG, is full (cleared when RCREG is read)
0= The EUSART receive buffer is empty
TXIF: EUSART Transmit Interrupt Flag bit
1= The EUSART transmit buffer, TXREG, is empty (cleared when TXREG is written)
0= The EUSART transmit buffer is full
SSPIF: Master Synchronous Serial Port Interrupt Flag bit
1= The transmission/reception is complete (must be cleared in software)
0= Waiting to transmit/receive
CCP1IF: CCP1 Interrupt Flag bit
Capture mode:
1= A TMR1 register capture occurred (must be cleared in software)
0= No TMR1 register capture occurred
Compare mode:
1= A TMR1 register compare match occurred (must be cleared in software)
0= No TMR1 register compare match occurred
PWM mode:
Unused in this mode.
bit 1
bit 0
TMR2IF: TMR2 to PR2 Match Interrupt Flag bit
1= TMR2 to PR2 match occurred (must be cleared in software)
0= No TMR2 to PR2 match occurred
TMR1IF: TMR1 Overflow Interrupt Flag bit
1= TMR1 register overflowed (must be cleared in software)
0= TMR1 register did not overflow
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS39631A-page 96
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 9-5:
PIR2: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 2
R/W-0
OSCFIF
bit 7
R/W-0
CMIF
U-0
—
R/W-0
EEIF
R/W-0
BCLIF
R/W-0
R/W-0
R/W-0
HLVDIF
TMR3IF
CCP2IF
bit 0
bit 7
bit 6
OSCFIF: Oscillator Fail Interrupt Flag bit
1= Device oscillator failed, clock input has changed to INTOSC (must be cleared in software)
0= Device clock operating
CMIF: Comparator Interrupt Flag bit
1= Comparator input has changed (must be cleared in software)
0= Comparator input has not changed
bit 5
bit 4
Unimplemented: Read as ‘0’
EEIF: Data EEPROM/Flash Write Operation Interrupt Flag bit
1= The write operation is complete (must be cleared in software)
0= The write operation is not complete or has not been started
bit 3
bit 2
BCLIF: Bus Collision Interrupt Flag bit
1= A bus collision occurred (must be cleared in software)
0= No bus collision occurred
HLVDIF: High/Low-Voltage Detect Interrupt Flag bit
1= A high/low-voltage condition occurred (direction determined by
VDIRMAG bit, HLVDCON<7>)
0= A high/low-voltage condition has not occurred
bit 1
bit 0
TMR3IF: TMR3 Overflow Interrupt Flag bit
1= TMR3 register overflowed (must be cleared in software)
0= TMR3 register did not overflow
CCP2IF: CCPx Interrupt Flag bit
Capture mode:
1= A TMR1 register capture occurred (must be cleared in software)
0= No TMR1 register capture occurred
Compare mode:
1= A TMR1 register compare match occurred (must be cleared in software)
0= No TMR1 register compare match occurred
PWM mode:
Unused in this mode.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 97
PIC18F2420/2520/4420/4520
9.3
PIE Registers
The PIE registers contain the individual enable bits for
the peripheral interrupts. Due to the number of periph-
eral interrupt sources, there are two Peripheral Interrupt
Enable registers (PIE1 and PIE2). When IPEN = 0, the
PEIE bit must be set to enable any of these peripheral
interrupts.
REGISTER 9-6:
PIE1: PERIPHERAL INTERRUPT ENABLE REGISTER 1
R/W-0
PSPIE(1)
bit 7
R/W-0
ADIE
R/W-0
RCIE
R/W-0
TXIE
R/W-0
SSPIE
R/W-0
R/W-0
R/W-0
TMR1IE
bit 0
CCP1IE
TMR2IE
bit 7
PSPIE: Parallel Slave Port Read/Write Interrupt Enable bit(1)
1= Enables the PSP read/write interrupt
0= Disables the PSP read/write interrupt
Note 1: This bit is unimplemented on 28-pin devices and will read as ‘0’.
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
ADIE: A/D Converter Interrupt Enable bit
1= Enables the A/D interrupt
0= Disables the A/D interrupt
RCIE: EUSART Receive Interrupt Enable bit
1= Enables the EUSART receive interrupt
0= Disables the EUSART receive interrupt
TXIE: EUSART Transmit Interrupt Enable bit
1= Enables the EUSART transmit interrupt
0= Disables the EUSART transmit interrupt
SSPIE: Master Synchronous Serial Port Interrupt Enable bit
1= Enables the MSSP interrupt
0= Disables the MSSP interrupt
CCP1IE: CCP1 Interrupt Enable bit
1= Enables the CCP1 interrupt
0= Disables the CCP1 interrupt
TMR2IE: TMR2 to PR2 Match Interrupt Enable bit
1= Enables the TMR2 to PR2 match interrupt
0= Disables the TMR2 to PR2 match interrupt
TMR1IE: TMR1 Overflow Interrupt Enable bit
1= Enables the TMR1 overflow interrupt
0= Disables the TMR1 overflow interrupt
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS39631A-page 98
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 9-7:
PIE2: PERIPHERAL INTERRUPT ENABLE REGISTER 2
R/W-0
OSCFIE
bit 7
R/W-0
CMIE
U-0
—
R/W-0
EEIE
R/W-0
BCLIE
R/W-0
R/W-0
R/W-0
HLVDIE
TMR3IE
CCP2IE
bit 0
bit 7
bit 6
OSCFIE: Oscillator Fail Interrupt Enable bit
1= Enabled
0= Disabled
CMIE: Comparator Interrupt Enable bit
1= Enabled
0= Disabled
bit 5
bit 4
Unimplemented: Read as ‘0’
EEIE: Data EEPROM/Flash Write Operation Interrupt Enable bit
1= Enabled
0= Disabled
bit 3
bit 2
bit 1
bit 0
BCLIE: Bus Collision Interrupt Enable bit
1= Enabled
0= Disabled
HLVDIE: High/Low-Voltage Detect Interrupt Enable bit
1= Enabled
0= Disabled
TMR3IE: TMR3 Overflow Interrupt Enable bit
1= Enabled
0= Disabled
CCP2IE: CCP2 Interrupt Enable bit
1= Enabled
0= Disabled
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 99
PIC18F2420/2520/4420/4520
9.4
IPR Registers
The IPR registers contain the individual priority bits for
the peripheral interrupts. Due to the number of periph-
eral interrupt sources, there are two Peripheral Interrupt
Priority registers (IPR1 and IPR2). Using the priority bits
requires that the Interrupt Priority Enable (IPEN) bit be
set.
REGISTER 9-8:
IPR1: PERIPHERAL INTERRUPT PRIORITY REGISTER 1
R/W-1
PSPIP(1)
bit 7
R/W-1
ADIP
R/W-1
RCIP
R/W-1
TXIP
R/W-1
SSPIP
R/W-1
R/W-1
R/W-1
TMR1IP
bit 0
CCP1IP
TMR2IP
bit 7
PSPIP: Parallel Slave Port Read/Write Interrupt Priority bit(1)
1= High priority
0= Low priority
Note 1: This bit is unimplemented on 28-pin devices and will read as ‘0’.
bit 6
bit 5
bit 4
ADIP: A/D Converter Interrupt Priority bit
1= High priority
0= Low priority
RCIP: EUSART Receive Interrupt Priority bit
1= High priority
0= Low priority
TXIP: EUSART Transmit Interrupt Priority bit
1= High priority
0= Low priority
bit 3
bit 2
bit 1
bit 0
SSPIP: Master Synchronous Serial Port Interrupt Priority bit
1= High priority
0= Low priority
CCP1IP: CCP1 Interrupt Priority bit
1= High priority
0= Low priority
TMR2IP: TMR2 to PR2 Match Interrupt Priority bit
1= High priority
0= Low priority
TMR1IP: TMR1 Overflow Interrupt Priority bit
1= High priority
0= Low priority
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS39631A-page 100
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 9-9:
IPR2: PERIPHERAL INTERRUPT PRIORITY REGISTER 2
R/W-1
OSCFIP
bit 7
R/W-1
CMIP
U-0
—
R/W-1
EEIP
R/W-1
BCLIP
R/W-1
R/W-1
R/W-1
HLVDIP
TMR3IP
CCP2IP
bit 0
bit 7
bit 6
OSCFIP: Oscillator Fail Interrupt Priority bit
1= High priority
0= Low priority
CMIP: Comparator Interrupt Priority bit
1= High priority
0= Low priority
bit 5
bit 4
Unimplemented: Read as ‘0’
EEIP: Data EEPROM/Flash Write Operation Interrupt Priority bit
1= High priority
0= Low priority
bit 3
bit 2
bit 1
bit 0
BCLIP: Bus Collision Interrupt Priority bit
1= High priority
0= Low priority
HLVDIP: High/Low-Voltage Detect Interrupt Priority bit
1= High priority
0= Low priority
TMR3IP: TMR3 Overflow Interrupt Priority bit
1= High priority
0= Low priority
CCP2IP: CCP2 Interrupt Priority bit
1= High priority
0= Low priority
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 101
PIC18F2420/2520/4420/4520
The operation of the SBOREN bit and the Reset flag
bits is discussed in more detail in Section 4.1 “RCON
Register”.
9.5
RCON Register
The RCON register contains flag bits which are used to
determine the cause of the last Reset or wake-up from
Idle or Sleep modes. RCON also contains the IPEN bit
which enables interrupt priorities.
REGISTER 9-10: RCON REGISTER
R/W-0
IPEN
R/W-1(1)
U-0
—
R/W-1
RI
R-1
TO
R-1
PD
R/W-0(1)
POR
R/W-0
BOR
SBOREN
bit 7
bit 0
bit 7
bit 6
IPEN: Interrupt Priority Enable bit
1= Enable priority levels on interrupts
0= Disable priority levels on interrupts (PIC16XXX Compatibility mode)
SBOREN: Software BOR Enable bit(1)
For details of bit operation, see Register 4-1.
Note 1: Actual Reset values are determined by device configuration and the nature of the
device Reset. See Register 4-1 for additional information.
bit 5
bit 4
Unimplemented: Read as ‘0’
RI: RESETInstruction Flag bit
For details of bit operation, see Register 4-1.
TO: Watchdog Time-out Flag bit
bit 3
bit 2
bit 1
bit 0
For details of bit operation, see Register 4-1.
PD: Power-down Detection Flag bit
For details of bit operation, see Register 4-1.
POR: Power-on Reset Status bit
For details of bit operation, see Register 4-1.
BOR: Brown-out Reset Status bit
For details of bit operation, see Register 4-1.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS39631A-page 102
Preliminary
2004 Microchip Technology Inc.
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9.6
INTn Pin Interrupts
9.7
TMR0 Interrupt
External interrupts on the RB0/INT0, RB1/INT1 and
RB2/INT2 pins are edge-triggered. If the corresponding
INTEDGx bit in the INTCON2 register is set (= 1), the
interrupt is triggered by a rising edge; if the bit is clear,
the trigger is on the falling edge. When a valid edge
appears on the RBx/INTx pin, the corresponding flag
bit, INTxF, is set. This interrupt can be disabled by
clearing the corresponding enable bit, INTxE. Flag bit,
INTxF, must be cleared in software in the Interrupt
Service Routine before re-enabling the interrupt.
In 8-bit mode (which is the default), an overflow in the
TMR0 register (FFh → 00h) will set flag bit, TMR0IF. In
16-bit mode, an overflow in the TMR0H:TMR0L regis-
ter pair (FFFFh → 0000h) will set TMR0IF. The interrupt
can be enabled/disabled by setting/clearing enable bit,
TMR0IE (INTCON<5>). Interrupt priority for Timer0 is
determined by the value contained in the interrupt pri-
ority bit, TMR0IP (INTCON2<2>). See Section 11.0
“Timer0 Module” for further details on the Timer0
module.
All external interrupts (INT0, INT1 and INT2) can wake-
up the processor from Idle or Sleep modes if bit INTxE
was set prior to going into those modes. If the Global
Interrupt Enable bit, GIE, is set, the processor will
branch to the interrupt vector following wake-up.
9.8
PORTB Interrupt-on-Change
An input change on PORTB<7:4> sets flag bit, RBIF
(INTCON<0>). The interrupt can be enabled/disabled
by setting/clearing enable bit, RBIE (INTCON<3>).
Interrupt priority for PORTB interrupt-on-change is
determined by the value contained in the interrupt
priority bit, RBIP (INTCON2<0>).
Interrupt priority for INT1 and INT2 is determined by the
value contained in the interrupt priority bits, INT1IP
(INTCON3<6>) and INT2IP (INTCON3<7>). There is
no priority bit associated with INT0. It is always a high
priority interrupt source.
9.9
Context Saving During Interrupts
During interrupts, the return PC address is saved on
the stack. Additionally, the WREG, Status and BSR reg-
isters are saved on the fast return stack. If a fast return
from interrupt is not used (see Section 5.3 “Data
Memory Organization”), the user may need to save
the WREG, Status and BSR registers on entry to the
Interrupt Service Routine. Depending on the user’s
application, other registers may also need to be saved.
Example 9-1 saves and restores the WREG, Status
and BSR registers during an Interrupt Service Routine.
EXAMPLE 9-1:
SAVING STATUS, WREG AND BSR REGISTERS IN RAM
MOVWF
MOVFF
MOVFF
;
W_TEMP
STATUS, STATUS_TEMP
BSR, BSR_TEMP
; W_TEMP is in virtual bank
; STATUS_TEMP located anywhere
; BSR_TMEP located anywhere
; USER ISR CODE
;
MOVFF
MOVF
MOVFF
BSR_TEMP, BSR
W_TEMP, W
STATUS_TEMP, STATUS
; Restore BSR
; Restore WREG
; Restore STATUS
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 103
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 104
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
Reading the PORTA register reads the status of the
pins, whereas writing to it, will write to the port latch.
10.0 I/O PORTS
Depending on the device selected and features
enabled, there are up to five ports available. Some pins
of the I/O ports are multiplexed with an alternate
function from the peripheral features on the device. In
general, when a peripheral is enabled, that pin may not
be used as a general purpose I/O pin.
The Data Latch (LATA) register is also memory mapped.
Read-modify-write operations on the LATA register read
and write the latched output value for PORTA.
The RA4 pin is multiplexed with the Timer0 module
clock input and one of the comparator outputs to
become the RA4/T0CKI/C1OUT pin. Pins RA6 and
RA7 are multiplexed with the main oscillator pins; they
are enabled as oscillator or I/O pins by the selection of
the main oscillator in the configuration register (see
Section 23.1 “Configuration Bits” for details). When
they are not used as port pins, RA6 and RA7 and their
associated TRIS and LAT bits are read as ‘0’.
Each port has three registers for its operation. These
registers are:
• TRIS register (data direction register)
• PORT register (reads the levels on the pins of the
device)
• LAT register (output latch)
The other PORTA pins are multiplexed with analog
inputs, the analog VREF+ and VREF- inputs and the com-
parator voltage reference output. The operation of pins
RA3:RA0 and RA5 as A/D converter inputs is selected
by clearing or setting the control bits in the ADCON1
register (A/D Control Register 1).
The Data Latch (LAT register) is useful for read-modify-
write operations on the value that the I/O pins are
driving.
A simplified model of a generic I/O port, without the
interfaces to other peripherals, is shown in Figure 10-1.
Pins RA0 through RA5 may also be used as comparator
inputs or outputs by setting the appropriate bits in the
CMCON register. To use RA3:RA0 as digital inputs, it is
also necessary to turn off the comparators.
FIGURE 10-1:
GENERIC I/O PORT
OPERATION
RD LAT
Note:
On a Power-on Reset, RA5 and RA3:RA0
are configured as analog inputs and read
as ‘0’. RA4 is configured as a digital input.
Data
Bus
D
Q
I/O pin(1)
WR LAT
or
The RA4/T0CKI/C1OUT pin is a Schmitt Trigger input.
All other PORTA pins have TTL input levels and full
CMOS output drivers.
Port
CK
Data Latch
D
Q
The TRISA register controls the direction of the PORTA
pins, even when they are being used as analog inputs.
The user must ensure the bits in the TRISA register are
maintained set when using them as analog inputs.
WR TRIS
RD TRIS
CK
TRIS Latch
Input
Buffer
EXAMPLE 10-1:
INITIALIZING PORTA
CLRF
PORTA
LATA
07h
; Initialize PORTA by
; clearing output
; data latches
; Alternate method
; to clear output
; data latches
Q
D
CLRF
EN
RD Port
MOVLW
MOVWF
MOVWF
MOVWF
MOVLW
; Configure A/D
ADCON1 ; for digital inputs
07h
CMCON
0CFh
Note 1: I/O pins have diode protection to VDD and VSS.
; Configure comparators
; for digital input
; Value used to
10.1 PORTA, TRISA and LATA Registers
; initialize data
; direction
PORTA is a 8-bit wide, bidirectional port. The corre-
sponding data direction register is TRISA. Setting a
TRISA bit (= 1) will make the corresponding PORTA pin
an input (i.e., put the corresponding output driver in a
high-impedance mode). Clearing a TRISA bit (= 0) will
make the corresponding PORTA pin an output (i.e., put
the contents of the output latch on the selected pin).
MOVWF
TRISA
; Set RA<3:0> as inputs
; RA<5:4> as outputs
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 105
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TABLE 10-1: PORTA I/O SUMMARY
TRIS
Setting
I/O
Type
Pin
RA0/AN0
Function
I/O
Description
RA0
0
1
1
O
I
DIG LATA<0> data output; not affected by analog input.
TTL PORTA<0> data input; disabled when analog input enabled.
AN0
RA1
I
ANA A/D input channel 0 and Comparator C1- input. Default input
configuration on POR; does not affect digital output.
RA1/AN1
0
1
1
O
I
DIG LATA<1> data output; not affected by analog input.
TTL PORTA<1> data input; disabled when analog input enabled.
AN1
RA2
I
ANA A/D input channel 1 and Comparator C2- input. Default input
configuration on POR; does not affect digital output.
RA2/AN2/
VREF-/CVREF
0
1
1
O
I
DIG LATA<2> data output; not affected by analog input. Disabled when
CVREF output enabled.
TTL PORTA<2> data input. Disabled when analog functions enabled;
disabled when CVREF output enabled.
AN2
I
ANA A/D input channel 2 and Comparator C2+ input. Default input
configuration on POR; not affected by analog output.
VREF-
1
x
I
ANA A/D and comparator voltage reference low input.
CVREF
O
ANA Comparator voltage reference output. Enabling this feature disables
digital I/O.
RA3/AN3/VREF+
RA3
AN3
0
1
1
O
I
DIG LATA<3> data output; not affected by analog input.
TTL PORTA<3> data input; disabled when analog input enabled.
I
ANA A/D input channel 3 and Comparator C1+ input. Default input
configuration on POR.
VREF+
RA4
1
0
1
1
0
0
1
1
1
1
0
0
1
I
O
I
ANA A/D and comparator voltage reference high input.
DIG LATA<4> data output.
RA4/T0CKI/C1OUT
ST
ST
PORTA<4> data input; default configuration on POR.
Timer0 clock input.
T0CKI
C1OUT
RA5
I
O
O
I
DIG Comparator 1 output; takes priority over port data.
DIG LATA<5> data output; not affected by analog input.
TTL PORTA<5> data input; disabled when analog input enabled.
ANA A/D input channel 4. Default configuration on POR.
TTL Slave select input for SSP (MSSP module).
RA5/AN4/SS/
HLVDIN/C2OUT
AN4
SS
I
I
HLVDIN
C2OUT
RA6
I
ANA High/Low-Voltage Detect external trip point input.
DIG Comparator 2 output; takes priority over port data.
DIG LATA<6> data output. Enabled in RCIO, INTIO2 and ECIO modes only.
O
O
I
OSC2/CLKO/RA6
OSC1/CLKI/RA7
TTL PORTA<6> data input. Enabled in RCIO, INTIO2 and ECIO modes
only.
OSC2
CLKO
x
x
O
O
ANA Main oscillator feedback output connection (XT, HS and LP modes).
DIG System cycle clock output (FOSC/4) in RC, INTIO1 and EC Oscillator
modes.
RA7
0
1
x
x
O
I
DIG LATA<7> data output. Disabled in external oscillator modes.
TTL PORTA<7> data input. Disabled in external oscillator modes.
ANA Main oscillator input connection.
OSC1
CLKI
I
I
ANA Main clock input connection.
Legend:
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output;
x= Don’t care (TRIS bit does not affect port direction or is overridden for this option).
DS39631A-page 106
Preliminary
2004 Microchip Technology Inc.
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TABLE 10-2: SUMMARY OF REGISTERS ASSOCIATED WITH PORTA
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
PORTA
RA7(1)
RA6(1)
RA5
RA4
RA3
RA2
RA1
RA0
52
52
52
51
51
51
LATA
LATA7(1) LATA6(1) PORTA Data Latch Register (Read and Write to Data Latch)
TRISA7(1) TRISA6(1) PORTA Data Direction Control Register
TRISA
ADCON1
CMCON
CVRCON
—
—
VCFG1
C2INV
CVRR
VCFG0
C1INV
PCFG3
CIS
PCFG2
CM2
PCFG1
CM1
PCFG0
CM0
C2OUT
CVREN
C1OUT
CVROE
CVRSS
CVR3
CVR2
CVR1
CVR0
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTA.
Note 1: RA7:RA6 and their associated latch and data direction bits are enabled as I/O pins based on oscillator
configuration; otherwise, they are read as ‘0’.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 107
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Four of the PORTB pins (RB7:RB4) have an interrupt-
10.2 PORTB, TRISB and LATB
Registers
on-change feature. Only pins configured as inputs can
cause this interrupt to occur (i.e., any RB7:RB4 pin
configured as an output is excluded from the interrupt-
on-change comparison). The input pins (of RB7:RB4)
are compared with the old value latched on the last
read of PORTB. The “mismatch” outputs of RB7:RB4
are ORed together to generate the RB Port Change
Interrupt with Flag bit, RBIF (INTCON<0>).
PORTB is an 8-bit wide, bidirectional port. The corre-
sponding data direction register is TRISB. Setting a
TRISB bit (= 1) will make the corresponding PORTB
pin an input (i.e., put the corresponding output driver in
a high-impedance mode). Clearing a TRISB bit (= 0)
will make the corresponding PORTB pin an output (i.e.,
put the contents of the output latch on the selected pin).
This interrupt can wake the device from the Sleep
mode, or any of the Idle modes. The user, in the
Interrupt Service Routine, can clear the interrupt in the
following manner:
The Data Latch register (LATB) is also memory
mapped. Read-modify-write operations on the LATB
register read and write the latched output value for
PORTB.
a) Any read or write of PORTB (except with the
MOVFF (ANY), PORTBinstruction).
EXAMPLE 10-2:
INITIALIZING PORTB
b) Clear flag bit, RBIF.
CLRF
PORTB
LATB
0Fh
; Initialize PORTB by
; clearing output
; data latches
; Alternate method
; to clear output
; data latches
A mismatch condition will continue to set flag bit, RBIF.
Reading PORTB will end the mismatch condition and
allow flag bit, RBIF, to be cleared.
CLRF
The interrupt-on-change feature is recommended for
wake-up on key depression operation and operations
where PORTB is only used for the interrupt-on-change
feature. Polling of PORTB is not recommended while
using the interrupt-on-change feature.
MOVLW
MOVWF
; Set RB<4:0> as
ADCON1 ; digital I/O pins
; (required if config bit
; PBADEN is set)
; Value used to
; initialize data
; direction
; Set RB<3:0> as inputs
; RB<5:4> as outputs
; RB<7:6> as inputs
MOVLW
MOVWF
0CFh
RB3 can be configured by the configuration bit,
CCP2MX, as the alternate peripheral pin for the CCP2
module (CCP2MX = 0).
TRISB
Each of the PORTB pins has a weak internal pull-up. A
single control bit can turn on all the pull-ups. This is per-
formed by clearing bit, RBPU (INTCON2<7>). The
weak pull-up is automatically turned off when the port
pin is configured as an output. The pull-ups are
disabled on a Power-on Reset.
Note:
On a Power-on Reset, RB4:RB0 are
configured as analog inputs by default and
read as ‘0’; RB7:RB5 are configured as
digital inputs.
By programming the configuration bit,
PBADEN, RB4:RB0 will alternatively be
configured as digital inputs on POR.
DS39631A-page 108
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 10-3: PORTB I/O SUMMARY
TRIS
Setting
I/O
Pin
Function
I/O
Description
Type
RB0/INT0/FLT0/
AN12
RB0
0
1
O
I
DIG
TTL
LATB<0> data output; not affected by analog input.
PORTB<0> data input; weak pull-up when RBPU bit is cleared.
(1)
Disabled when analog input enabled.
INT0
FLT0
AN12
RB1
1
1
1
0
1
I
I
ST
ST
External interrupt 0 input.
Enhanced PWM Fault input (ECCP1 module); enabled in software.
(1)
I
ANA
DIG
TTL
A/D input channel 12.
RB1/INT1/AN10
RB2/INT2/AN8
RB3/AN9/CCP2
O
I
LATB<1> data output; not affected by analog input.
PORTB<1> data input; weak pull-up when RBPU bit is cleared.
Disabled when analog input enabled.
(1)
INT1
AN10
RB2
1
1
0
1
I
I
ST
ANA
DIG
TTL
External Interrupt 1 input.
(1)
A/D input channel 10.
O
I
LATB<2> data output; not affected by analog input.
PORTB<2> data input; weak pull-up when RBPU bit is cleared.
Disabled when analog input enabled.
(1)
INT2
AN8
RB3
1
1
0
1
I
I
ST
ANA
DIG
TTL
External interrupt 2 input.
(1)
A/D input channel 8.
O
I
LATB<3> data output; not affected by analog input.
PORTB<3> data input; weak pull-up when RBPU bit is cleared.
Disabled when analog input enabled.
(1)
(1)
AN9
1
0
1
0
1
I
O
I
ANA
DIG
ST
A/D input channel 9.
(2)
CCP2
CCP2 compare and PWM output.
CCP2 capture input
RB4/KBI0/AN11
RB5/KBI1/PGM
RB4
O
I
DIG
TTL
LATB<4> data output; not affected by analog input.
PORTB<4> data input; weak pull-up when RBPU bit is cleared.
Disabled when analog input enabled.
(1)
KBI0
AN11
RB5
1
1
0
1
1
x
I
I
TTL
ANA
DIG
TTL
TTL
ST
Interrupt on pin change.
(1)
A/D input channel 11.
O
I
LATB<5> data output.
PORTB<5> data input; weak pull-up when RBPU bit is cleared.
Interrupt on pin change.
KBI1
PGM
I
I
Single-Supply Programming mode entry (ICSP™). Enabled by LVP
configuration bit; all other pin functions disabled.
RB6/KBI2/PGC
RB7/KBI3/PGD
RB6
0
1
1
x
0
1
1
x
x
O
I
DIG
TTL
TTL
ST
LATB<6> data output.
PORTB<6> data input; weak pull-up when RBPU bit is cleared.
Interrupt on pin change.
KBI2
PGC
RB7
I
(3)
I
Serial execution (ICSP) clock input for ICSP and ICD operation.
O
I
DIG
TTL
TTL
DIG
ST
LATB<7> data output.
PORTB<7> data input; weak pull-up when RBPU bit is cleared.
Interrupt on pin change.
KBI3
PGD
I
(3)
O
I
Serial execution data output for ICSP and ICD operation.
(3)
Serial execution data input for ICSP and ICD operation.
Legend:
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output;
x= Don’t care (TRIS bit does not affect port direction or is overridden for this option).
Note 1: Configuration on POR is determined by the PBADEN configuration bit. Pins are configured as analog inputs by default
when PBADEN is set and digital inputs when PBADEN is cleared.
2: Alternate assignment for CCP2 when the CCP2MX configuration bit is ‘0’. Default assignment is RC1.
3: All other pin functions are disabled when ICSP or ICD are enabled.
2004 Microchip Technology Inc.
Preliminary
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TABLE 10-4: SUMMARY OF REGISTERS ASSOCIATED WITH PORTB
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
PORTB
RB7
RB6
RB5
RB4
RB3
RB2
RB1
RB0
52
52
52
49
49
49
51
LATB
PORTB Data Latch Register (Read and Write to Data Latch)
PORTB Data Direction Control Register
TRISB
INTCON
INTCON2
INTCON3
ADCON1
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
RBIE
—
TMR0IF
TMR0IP
—
INT0IF
—
RBIF
RBIP
RBPU
INT2IP
—
INTEDG0 INTEDG1 INTEDG2
INT1IP
—
—
INT2IE
VCFG0
INT1IE
PCFG3
INT2IF
PCFG1
INT1IF
PCFG0
VCFG1
PCFG2
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTB.
DS39631A-page 110
Preliminary
2004 Microchip Technology Inc.
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10.3 PORTC, TRISC and LATC
Registers
Note:
On a Power-on Reset, these pins are
configured as digital inputs.
PORTC is an 8-bit wide, bidirectional port. The corre-
sponding data direction register is TRISC. Setting a
TRISC bit (= 1) will make the corresponding PORTC
pin an input (i.e., put the corresponding output driver in
a high-impedance mode). Clearing a TRISC bit (= 0)
will make the corresponding PORTC pin an output (i.e.,
put the contents of the output latch on the selected pin).
The contents of the TRISC register are affected by
peripheral overrides. Reading TRISC always returns
the current contents, even though a peripheral device
may be overriding one or more of the pins.
EXAMPLE 10-3:
INITIALIZING PORTC
CLRF
PORTC
; Initialize PORTC by
; clearing output
; data latches
The Data Latch register (LATC) is also memory
mapped. Read-modify-write operations on the LATC
register read and write the latched output value for
PORTC.
CLRF
LATC
; Alternate method
; to clear output
; data latches
PORTC is multiplexed with several peripheral functions
(Table 10-5). The pins have Schmitt Trigger input buff-
ers. RC1 is normally configured by configuration bit,
CCP2MX, as the default peripheral pin of the CCP2
module (default/erased state, CCP2MX = 1).
MOVLW
MOVWF
0CFh
; Value used to
; initialize data
; direction
; Set RC<3:0> as inputs
; RC<5:4> as outputs
; RC<7:6> as inputs
TRISC
When enabling peripheral functions, care should be
taken in defining TRIS bits for each PORTC pin. Some
peripherals override the TRIS bit to make a pin an output,
while other peripherals override the TRIS bit to make a
pin an input. The user should refer to the corresponding
peripheral section for additional information.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 111
PIC18F2420/2520/4420/4520
TABLE 10-5: PORTC I/O SUMMARY
TRIS
Setting
I/O
Type
Pin
Function
I/O
Description
RC0/T1OSO/
T13CKI
RC0
0
1
x
O
I
DIG
ST
LATC<0> data output.
PORTC<0> data input.
T1OSO
O
ANA
Timer1 oscillator output; enabled when Timer1 oscillator enabled.
Disables digital I/O.
T13CKI
RC1
1
0
1
x
I
O
I
ST
DIG
ST
Timer1/Timer3 counter input.
LATC<1> data output.
RC1/T1OSI/CCP2
PORTC<1> data input.
T1OSI
I
ANA
Timer1 oscillator input; enabled when Timer1 oscillator enabled.
Disables digital I/O.
(1)
CCP2
0
1
0
1
0
1
0
O
I
DIG
ST
CCP2 compare and PWM output; takes priority over port data.
CCP2 capture input.
RC2/CCP1/P1A
RC2
O
I
DIG
ST
LATC<2> data output.
PORTC<2> data input.
CCP1
O
I
DIG
ST
ECCP1 compare or PWM output; takes priority over port data.
ECCP1 capture input.
(2)
P1A
O
DIG
ECCP1 Enhanced PWM output, channel A. May be configured for
tri-state during Enhanced PWM shutdown events. Takes priority over
port data.
RC3/SCK/SCL
RC3
SCK
SCL
RC4
0
1
0
1
0
1
0
1
1
1
1
0
1
0
0
1
1
O
I
DIG
ST
LATC<3> data output.
PORTC<3> data input.
O
I
DIG
ST
SPI™ clock output (MSSP module); takes priority over port data.
SPI clock input (MSSP module).
2
O
I
DIG
I C™ clock output (MSSP module); takes priority over port data.
2
2
I C/SMB I C clock input (MSSP module); input type depends on module setting.
RC4/SDI/SDA
O
I
DIG
ST
LATC<4> data output.
PORTC<4> data input.
SDI
I
ST
SPI data input (MSSP module).
2
SDA
O
I
DIG
I C data output (MSSP module); takes priority over port data.
2
2
I C/SMB I C data input (MSSP module); input type depends on module setting.
RC5/SDO
RC5
O
I
DIG
ST
LATC<5> data output.
PORTC<5> data input.
SDO
RC6
O
O
I
DIG
DIG
ST
SPI data output (MSSP module); takes priority over port data.
LATC<6> data output.
RC6/TX/CK
PORTC<6> data input.
TX
CK
O
DIG
Asynchronous serial transmit data output (USART module);
takes priority over port data. User must configure as output.
1
O
DIG
Synchronous serial clock output (USART module); takes priority
over port data.
1
0
1
1
1
I
O
I
ST
DIG
ST
Synchronous serial clock input (USART module).
LATC<7> data output.
RC7/RX/DT
RC7
PORTC<7> data input.
RX
DT
I
ST
Asynchronous serial receive data input (USART module).
O
DIG
Synchronous serial data output (USART module); takes priority over
port data.
1
I
ST
Synchronous serial data input (USART module). User must
configure as an input.
Legend:
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output;
I C/SMB = I C/SMBus input buffer; x= Don’t care (TRIS bit does not affect port direction or is overridden for this option).
2
2
Note 1: Default assignment for CCP2 when the CCP2MX configuration bit is set. Alternate assignment is RB3.
2: Enhanced PWM output is available only on PIC18F4520 devices.
DS39631A-page 112
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 10-6: SUMMARY OF REGISTERS ASSOCIATED WITH PORTC
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
PORTC
RC7
RC6
RC5
RC4
RC3
RC2
RC1
RC0
52
52
52
LATC
PORTC Data Latch Register (Read and Write to Data Latch)
PORTC Data Direction Control Register
TRISC
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 113
PIC18F2420/2520/4420/4520
PORTD can also be configured as an 8-bit wide micro-
10.4 PORTD, TRISD and LATD
Registers
processor port (Parallel Slave Port) by setting control
bit, PSPMODE (TRISE<4>). In this mode, the input
buffers are TTL. See Section 10.6 “Parallel Slave
Port” for additional information on the Parallel Slave
Port (PSP).
Note:
PORTD is only available on 40/44-pin
devices.
PORTD is an 8-bit wide, bidirectional port. The corre-
sponding data direction register is TRISD. Setting a
TRISD bit (= 1) will make the corresponding PORTD
pin an input (i.e., put the corresponding output driver in
a high-impedance mode). Clearing a TRISD bit (= 0)
will make the corresponding PORTD pin an output (i.e.,
put the contents of the output latch on the selected pin).
Note:
When the enhanced PWM mode is used
with either dual or quad outputs, the PSP
functions of PORTD are automatically
disabled.
EXAMPLE 10-4:
INITIALIZING PORTD
CLRF
PORTD
; Initialize PORTD by
; clearing output
; data latches
; Alternate method
; to clear output
; data latches
; Value used to
; initialize data
; direction
The Data Latch register (LATD) is also memory
mapped. Read-modify-write operations on the LATD
register read and write the latched output value for
PORTD.
CLRF
LATD
All pins on PORTD are implemented with Schmitt Trig-
ger input buffers. Each pin is individually configurable
as an input or output.
MOVLW
MOVWF
0CFh
Three of the PORTD pins are multiplexed with outputs
P1B, P1C and P1D of the enhanced CCP module. The
operation of these additional PWM output pins is
covered in greater detail in Section 16.0 “Enhanced
Capture/Compare/PWM (ECCP) Module”.
TRISD
; Set RD<3:0> as inputs
; RD<5:4> as outputs
; RD<7:6> as inputs
Note:
On a Power-on Reset, these pins are
configured as digital inputs.
DS39631A-page 114
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 10-7: PORTD I/O SUMMARY
TRIS
Setting
I/O
Pin
Function
I/O
Description
Type
RD0/PSP0
RD0
0
1
x
x
0
1
x
x
0
1
x
x
0
1
x
x
0
1
x
x
0
1
x
x
0
O
I
DIG
ST
LATD<0> data output.
PORTD<0> data input.
PSP0
RD1
O
I
DIG
TTL
DIG
ST
PSP read data output (LATD<0>); takes priority over port data.
PSP write data input.
RD1/PSP1
RD2/PSP2
RD3/PSP3
RD4/PSP4
RD5/PSP5/P1B
O
I
LATD<1> data output.
PORTD<1> data input.
PSP1
RD2
O
I
DIG
TTL
DIG
ST
PSP read data output (LATD<1>); takes priority over port data.
PSP write data input.
O
I
LATD<2> data output.
PORTD<2> data input.
PSP2
RD3
O
I
DIG
TTL
DIG
ST
PSP read data output (LATD<2>); takes priority over port data.
PSP write data input.
O
I
LATD<3> data output.
PORTD<3> data input.
PSP3
RD4
O
I
DIG
TTL
DIG
ST
PSP read data output (LATD<3>); takes priority over port data.
PSP write data input.
O
I
LATD<4> data output.
PORTD<4> data input.
PSP4
RD5
O
I
DIG
TTL
DIG
ST
PSP read data output (LATD<4>); takes priority over port data.
PSP write data input.
O
I
LATD<5> data output.
PORTD<5> data input.
PSP5
P1B
O
I
DIG
TTL
DIG
PSP read data output (LATD<5>); takes priority over port data.
PSP write data input.
O
ECCP1 Enhanced PWM output, channel B; takes priority over port and
PSP data. May be configured for tri-state during Enhanced PWM
shutdown events.
RD6/PSP6/P1C
RD6
PSP6
P1C
0
1
x
x
0
O
I
DIG
ST
LATD<6> data output.
PORTD<6> data input.
O
I
DIG
TTL
DIG
PSP read data output (LATD<6>); takes priority over port data.
PSP write data input.
O
ECCP1 Enhanced PWM output, channel C; takes priority over port and
PSP data. May be configured for tri-state during Enhanced PWM
shutdown events.
RD7/PSP7/P1D
RD7
PSP7
P1D
0
1
x
x
0
O
I
DIG
ST
LATD<7> data output.
PORTD<7> data input.
O
I
DIG
TTL
DIG
PSP read data output (LATD<7>); takes priority over port data.
PSP write data input.
O
ECCP1 Enhanced PWM output, channel D; takes priority over port and
PSP data. May be configured for tri-state during Enhanced PWM
shutdown events.
Legend:
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; x= Don’t care
(TRIS bit does not affect port direction or is overridden for this option).
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 115
PIC18F2420/2520/4420/4520
TABLE 10-8: SUMMARY OF REGISTERS ASSOCIATED WITH PORTD
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
PORTD
LATD
RD7
RD6
RD5
RD4
RD3
RD2
RD1
RD0
52
52
52
52
51
PORTD Data Latch Register (Read and Write to Data Latch)
PORTD Data Direction Control Register
TRISD
TRISE
IBF
OBF
IBOV
PSPMODE
—
TRISE2
TRISE1
TRISE0
CCP1CON
P1M1
P1M0
DC1B1
DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTD.
DS39631A-page 116
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
The fourth pin of PORTE (MCLR/VPP/RE3) is an input
only pin. Its operation is controlled by the MCLRE con-
figuration bit. When selected as a port pin (MCLRE = 0),
10.5 PORTE, TRISE and LATE
Registers
Depending on the particular PIC18F2420/2520/4420/
4520 device selected, PORTE is implemented in two
different ways.
it functions as a digital input only pin; as such, it does not
have TRIS or LAT bits associated with its operation.
Otherwise, it functions as the device’s Master Clear
input. In either configuration, RE3 also functions as the
programming voltage input during programming.
For 40/44-pin devices, PORTE is a 4-bit wide port.
Three pins (RE0/RD/AN5, RE1/WR/AN6 and RE2/CS/
AN7) are individually configurable as inputs or outputs.
These pins have Schmitt Trigger input buffers. When
selected as an analog input, these pins will read as ‘0’s.
Note:
On a Power-on Reset, RE3 is enabled as
digital input only if Master Clear
functionality is disabled.
a
The corresponding data direction register is TRISE.
Setting a TRISE bit (= 1) will make the corresponding
PORTE pin an input (i.e., put the corresponding output
driver in a high-impedance mode). Clearing a TRISE bit
(= 0) will make the corresponding PORTE pin an output
(i.e., put the contents of the output latch on the selected
pin).
EXAMPLE 10-5:
INITIALIZING PORTE
CLRF
PORTE
LATE
0Ah
; Initialize PORTE by
; clearing output
; data latches
; Alternate method
; to clear output
; data latches
CLRF
TRISE controls the direction of the RE pins, even when
they are being used as analog inputs. The user must
make sure to keep the pins configured as inputs when
using them as analog inputs.
MOVLW
MOVWF
MOVLW
; Configure A/D
ADCON1 ; for digital inputs
03h
; Value used to
; initialize data
; direction
; Set RE<0> as inputs
; RE<1> as outputs
; RE<2> as inputs
Note:
On a Power-on Reset, RE2:RE0 are
configured as analog inputs.
MOVWF
TRISE
The upper four bits of the TRISE register also control
the operation of the Parallel Slave Port. Their operation
is explained in Register 10-1.
10.5.1
PORTE IN 28-PIN DEVICES
For 28-pin devices, PORTE is only available when
Master Clear functionality is disabled (MCLRE = 0). In
these cases, PORTE is a single bit, input only port com-
prised of RE3 only. The pin operates as previously
described.
The Data Latch register (LATE) is also memory
mapped. Read-modify-write operations on the LATE
register, read and write the latched output value for
PORTE.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 117
PIC18F2420/2520/4420/4520
REGISTER 10-1: TRISE REGISTER (40/44-PIN DEVICES ONLY)
R-0
IBF
R-0
R/W-0
IBOV
R/W-0
U-0
—
R/W-1
R/W-1
R/W-1
OBF
PSPMODE
TRISE2
TRISE1
TRISE0
bit 7
bit 0
bit 7
bit 6
bit 5
bit 4
IBF: Input Buffer Full Status bit
1= A word has been received and waiting to be read by the CPU
0= No word has been received
OBF: Output Buffer Full Status bit
1= The output buffer still holds a previously written word
0= The output buffer has been read
IBOV: Input Buffer Overflow Detect bit (in Microprocessor mode)
1= A write occurred when a previously input word has not been read (must be cleared in software)
0= No overflow occurred
PSPMODE: Parallel Slave Port Mode Select bit
1= Parallel Slave Port mode
0= General purpose I/O mode
bit 3
bit 2
Unimplemented: Read as ‘0’
TRISE2: RE2 Direction Control bit
1= Input
0= Output
bit 1
bit 0
TRISE1: RE1 Direction Control bit
1= Input
0= Output
TRISE0: RE0 Direction Control bit
1= Input
0= Output
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS39631A-page 118
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 10-9: PORTE I/O SUMMARY
TRIS
Setting
I/O
Pin
Function
I/O
Description
Type
RE0/RD/AN5
RE0
0
1
1
1
0
1
1
1
0
1
1
1
—
O
I
DIG
ST
LATE<0> data output; not affected by analog input.
PORTE<0> data input; disabled when analog input enabled.
PSP read enable input (PSP enabled).
RD
I
TTL
ANA
DIG
ST
AN5
RE1
I
A/D input channel 5; default input configuration on POR.
LATE<1> data output; not affected by analog input.
PORTE<1> data input; disabled when analog input enabled.
PSP write enable input (PSP enabled).
RE1/WR/AN6
RE2/CS/AN7
MCLR/VPP/RE3
O
I
WR
AN6
RE2
I
TTL
ANA
DIG
ST
I
A/D input channel 6; default input configuration on POR.
LATE<2> data output; not affected by analog input.
PORTE<2> data input; disabled when analog input enabled.
PSP write enable input (PSP enabled).
O
I
CS
AN7
I
TTL
ANA
ST
I
A/D input channel 7; default input configuration on POR.
(1)
MCLR
I
External Master Clear input; enabled when MCLRE configuration bit is
set.
VPP
—
I
I
ANA
ST
High-voltage detection; used for ICSP™ mode entry detection. Always
available, regardless of pin mode.
(2)
RE3
—
PORTE<3> data input; enabled when MCLRE configuration bit is clear.
Legend:
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output;
x= Don’t care (TRIS bit does not affect port direction or is overridden for this option).
Note 1: RE3 is available on both 28-pin and 40/44-pin devices. All other PORTE pins are only implemented on 40/44-pin
devices.
2: RE3 does not have a corresponding TRIS bit to control data direction.
TABLE 10-10: SUMMARY OF REGISTERS ASSOCIATED WITH PORTE
Reset
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Values
on page
PORTE
LATE(2)
TRISE
—
—
—
—
—
—
—
—
RE3(1,2)
—
RE2
RE1
RE0
52
52
52
51
LATE Data Output Register
IBF
—
OBF
—
IBOV
VCFG1
PSPMODE
VCFG0
—
TRISE2
PCFG2
TRISE1
PCFG1
TRISE0
PCFG0
ADCON1
PCFG3
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTE.
Note 1: Implemented only when Master Clear functionality is disabled (MCLRE configuration bit = 0).
2: RE3 is the only PORTE bit implemented on both 28-pin and 40/44-pin devices. All other bits are
implemented only when PORTE is implemented (i.e., 40/44-pin devices).
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 119
PIC18F2420/2520/4420/4520
The timing for the control signals in Write and Read
modes is shown in Figure 10-3 and Figure 10-4,
respectively.
10.6 Parallel Slave Port
Note:
The Parallel Slave Port is only available on
40/44-pin devices.
FIGURE 10-2:
PORTD AND PORTE
BLOCK DIAGRAM
(PARALLEL SLAVE PORT)
In addition to its function as a general I/O port, PORTD
can also operate as an 8-bit wide Parallel Slave Port
(PSP) or microprocessor port. PSP operation is con-
trolled by the 4 upper bits of the TRISE register
(Register 10-1). Setting control bit, PSPMODE
(TRISE<4>), enables PSP operation as long as the
enhanced CCP module is not operating in dual output
or quad output PWM mode. In Slave mode, the port is
asynchronously readable and writable by the external
world.
One bit of PORTD
Data Bus
D
Q
RDx pin
WR LATD
or
WR PORTD
CK
Data Latch
TTL
The PSP can directly interface to an 8-bit micro-
processor data bus. The external microprocessor can
read or write the PORTD latch as an 8-bit latch. Setting
the control bit, PSPMODE, enables the PORTE I/O
pins to become control inputs for the microprocessor
port. When set, port pin RE0 is the RD input, RE1 is the
WR input and RE2 is the CS (Chip Select) input. For
this functionality, the corresponding data direction bits
of the TRISE register (TRISE<2:0>) must be config-
ured as inputs (set). The A/D port configuration bits,
PFCG3:PFCG0 (ADCON1<3:0>), must also be set to a
value in the range of ‘1010’ through ‘1111’.
Q
D
RD PORTD
RD LATD
EN
Set Interrupt Flag
PSPIF (PIR1<7>)
A write to the PSP occurs when both the CS and WR
lines are first detected low and ends when either are
detected high. The PSPIF and IBF flag bits are both set
when the write ends.
PORTE Pins
Read
RD
CS
WR
TTL
Chip Select
TTL
A read from the PSP occurs when both the CS and RD
lines are first detected low. The data in PORTD is read
out and the OBF bit is clear. If the user writes new data
to PORTD to set OBF, the data is immediately read out;
however, the OBF bit is not set.
Write
TTL
Note:
I/O pins have diode protection to VDD and VSS.
When either the CS or RD lines are detected high, the
PORTD pins return to the input state and the PSPIF bit
is set. User applications should wait for PSPIF to be set
before servicing the PSP; when this happens, the IBF
and OBF bits can be polled and the appropriate action
taken.
DS39631A-page 120
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 10-3:
PARALLEL SLAVE PORT WRITE WAVEFORMS
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
CS
WR
RD
PORTD<7:0>
IBF
OBF
PSPIF
FIGURE 10-4:
PARALLEL SLAVE PORT READ WAVEFORMS
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
CS
WR
RD
PORTD<7:0>
IBF
OBF
PSPIF
TABLE 10-11: REGISTERS ASSOCIATED WITH PARALLEL SLAVE PORT
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
PORTD
LATD
RD7
RD6
RD5
RD4
RD3
RD2
RD1
RD0
RE0
52
52
52
52
52
52
49
52
52
52
51
PORTD Data Latch Register (Read and Write to Data Latch)
PORTD Data Direction Control Register
TRISD
PORTE
LATE
—
—
—
—
—
—
—
—
RE3
—
RE2
RE1
LATE Data Output bits
TRISE
INTCON
PIR1
IBF
OBF
IBOV
PSPMODE
INT0IE
TXIF
—
TRISE2
TMR0IF
CCP1IF
TRISE1
INT0IF
TRISE0
RBIF
GIE/GIEH PEIE/GIEL TMR0IF
RBIE
SSPIF
SSPIE
SSPIP
PCFG3
PSPIF
PSPIE
PSPIP
—
ADIF
ADIE
ADIP
—
RCIF
RCIE
TMR2IF
TMR1IF
PIE1
TXIE
CCP1IE TMR2IE TMR1IE
CCP1IP TMR2IP TMR1IP
IPR1
RCIP
TXIP
ADCON1
VCFG1
VCFG0
PCFG2
PCFG1
PCFG0
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Parallel Slave Port.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 121
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 122
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
The T0CON register (Register 11-1) controls all
aspects of the module’s operation, including the
prescale selection. It is both readable and writable.
11.0 TIMER0 MODULE
The Timer0 module incorporates the following features:
• Software selectable operation as a timer or
counter in both 8-bit or 16-bit modes
A simplified block diagram of the Timer0 module in 8-bit
mode is shown in Figure 11-1. Figure 11-2 shows a
simplified block diagram of the Timer0 module in 16-bit
mode.
• Readable and writable registers
• Dedicated 8-bit, software programmable
prescaler
• Selectable clock source (internal or external)
• Edge select for external clock
• Interrupt-on-overflow
REGISTER 11-1: T0CON: TIMER0 CONTROL REGISTER
R/W-1
TMR0ON
bit 7
R/W-1
R/W-1
T0CS
R/W-1
T0SE
R/W-1
PSA
R/W-1
T0PS2
R/W-1
T0PS1
R/W-1
T0PS0
T08BIT
bit 0
bit 7
bit 6
bit 5
bit 4
bit 3
TMR0ON: Timer0 On/Off Control bit
1= Enables Timer0
0= Stops Timer0
T08BIT: Timer0 8-bit/16-bit Control bit
1= Timer0 is configured as an 8-bit timer/counter
0= Timer0 is configured as a 16-bit timer/counter
T0CS: Timer0 Clock Source Select bit
1= Transition on T0CKI pin
0= Internal instruction cycle clock (CLKO)
T0SE: Timer0 Source Edge Select bit
1= Increment on high-to-low transition on T0CKI pin
0= Increment on low-to-high transition on T0CKI pin
PSA: Timer0 Prescaler Assignment bit
1= TImer0 prescaler is NOT assigned. Timer0 clock input bypasses prescaler.
0= Timer0 prescaler is assigned. Timer0 clock input comes from prescaler output.
bit 2-0 T0PS2:T0PS0: Timer0 Prescaler Select bits
111= 1:256 prescale value
110= 1:128 prescale value
101= 1:64 prescale value
100= 1:32 prescale value
011= 1:16 prescale value
010= 1:8 prescale value
001= 1:4 prescale value
000= 1:2 prescale value
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 123
PIC18F2420/2520/4420/4520
internal phase clock (TOSC). There is a delay between
synchronization and the onset of incrementing the
timer/counter.
11.1 Timer0 Operation
Timer0 can operate as either a timer or a counter; the
mode is selected with the T0CS bit (T0CON<5>). In
Timer mode (T0CS = 0), the module increments on
every clock by default unless a different prescaler value
is selected (see Section 11.3 “Prescaler”). If the
TMR0 register is written to, the increment is inhibited
for the following two instruction cycles. The user can
work around this by writing an adjusted value to the
TMR0 register.
11.2 Timer0 Reads and Writes in
16-Bit Mode
TMR0H is not the actual high byte of Timer0 in 16-bit
mode; it is actually a buffered version of the real high
byte of Timer0 which is not directly readable nor writ-
able (refer to Figure 11-2). TMR0H is updated with the
contents of the high byte of Timer0 during a read of
TMR0L. This provides the ability to read all 16 bits of
Timer0 without having to verify that the read of the high
and low byte were valid, due to a rollover between
successive reads of the high and low byte.
The Counter mode is selected by setting the T0CS bit
(= 1). In this mode, Timer0 increments either on every
rising or falling edge of pin RA4/T0CKI. The increment-
ing edge is determined by the Timer0 Source Edge
Select bit, T0SE (T0CON<4>); clearing this bit selects
the rising edge. Restrictions on the external clock input
are discussed below.
Similarly, a write to the high byte of Timer0 must also
take place through the TMR0H Buffer register. The high
byte is updated with the contents of TMR0H when a
write occurs to TMR0L. This allows all 16 bits of Timer0
to be updated at once.
An external clock source can be used to drive Timer0;
however, it must meet certain requirements to ensure
that the external clock can be synchronized with the
FIGURE 11-1:
TIMER0 BLOCK DIAGRAM (8-BIT MODE)
FOSC/4
0
1
0
1
Set
TMR0IF
on Overflow
Sync with
Internal
Clocks
TMR0L
8
Programmable
Prescaler
T0CKI pin
(2 TCY Delay)
T0SE
T0CS
3
T0PS2:T0PS0
PSA
8
Internal Data Bus
Note: Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale.
FIGURE 11-2:
TIMER0 BLOCK DIAGRAM (16-BIT MODE)
FOSC/4
0
0
Sync with
Internal
Clocks
Set
TMR0
High Byte
1
TMR0L
TMR0IF
Programmable
Prescaler
on Overflow
T0CKI pin
1
8
(2 TCY Delay)
T0SE
T0CS
3
Read TMR0L
Write TMR0L
T0PS2:T0PS0
PSA
8
8
TMR0H
8
8
Internal Data Bus
Note: Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale.
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11.3.1
SWITCHING PRESCALER
ASSIGNMENT
11.3 Prescaler
An 8-bit counter is available as a prescaler for the Timer0
module. The prescaler is not directly readable or writable;
its value is set by the PSA and T0PS2:T0PS0 bits
(T0CON<3:0>) which determine the prescaler
assignment and prescale ratio.
The prescaler assignment is fully under software
control and can be changed “on-the-fly” during program
execution.
11.4 Timer0 Interrupt
Clearing the PSA bit assigns the prescaler to the
Timer0 module. When it is assigned, prescale values
from 1:2 through 1:256 in power-of-2 increments are
selectable.
The TMR0 interrupt is generated when the TMR0 reg-
ister overflows from FFh to 00h in 8-bit mode, or from
FFFFh to 0000h in 16-bit mode. This overflow sets the
TMR0IF flag bit. The interrupt can be masked by clear-
ing the TMR0IE bit (INTCON<5>). Before re-enabling
the interrupt, the TMR0IF bit must be cleared in
software by the Interrupt Service Routine.
When assigned to the Timer0 module, all instructions
writing to the TMR0 register (e.g., CLRF TMR0, MOVWF
TMR0, BSF TMR0, etc.) clear the prescaler count.
Note:
Writing to TMR0 when the prescaler is
assigned to Timer0 will clear the prescaler
count but will not change the prescaler
assignment.
Since Timer0 is shut down in Sleep mode, the TMR0
interrupt cannot awaken the processor from Sleep.
TABLE 11-1: REGISTERS ASSOCIATED WITH TIMER0
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TMR0L
Timer0 Register, Low Byte
Timer0 Register, High Byte
50
50
49
50
52
TMR0H
INTCON
T0CON
TRISA
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
T0SE
RA4
RBIE
PSA
RA3
TMR0IF
T0PS2
RA2
INT0IF
T0PS1
RA1
RBIF
T0PS0
RA0
TMR0ON
RA7(1)
T08BIT
RA6(1)
T0CS
RA5
Legend: Shaded cells are not used by Timer0.
Note 1: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary
oscillator modes. When disabled, these bits read as ‘0’.
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NOTES:
DS39631A-page 126
Preliminary
2004 Microchip Technology Inc.
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A simplified block diagram of the Timer1 module is
shown in Figure 12-1. A block diagram of the module’s
operation in Read/Write mode is shown in Figure 12-2.
12.0 TIMER1 MODULE
The Timer1 timer/counter module incorporates these
features:
The module incorporates its own low-power oscillator
to provide an additional clocking option. The Timer1
oscillator can also be used as a low-power clock source
for the microcontroller in power managed operation.
• Software selectable operation as a 16-bit timer or
counter
• Readable and writable 8-bit registers (TMR1H
and TMR1L)
Timer1 can also be used to provide Real-Time Clock
(RTC) functionality to applications with only a minimal
addition of external components and code overhead.
• Selectable clock source (internal or external) with
device clock or Timer1 oscillator internal options
• Interrupt-on-overflow
Timer1 is controlled through the T1CON Control
register (Register 12-1). It also contains the Timer1
Oscillator Enable bit (T1OSCEN). Timer1 can be
enabled or disabled by setting or clearing control bit,
TMR1ON (T1CON<0>).
• Reset on CCP Special Event Trigger
• Device clock status flag (T1RUN)
REGISTER 12-1: T1CON: TIMER1 CONTROL REGISTER
R/W-0
RD16
R-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON
bit 0
bit 7
bit 7
bit 6
RD16: 16-bit Read/Write Mode Enable bit
1= Enables register read/write of TImer1 in one 16-bit operation
0= Enables register read/write of Timer1 in two 8-bit operations
T1RUN: Timer1 System Clock Status bit
1= Device clock is derived from Timer1 oscillator
0= Device clock is derived from another source
bit 5-4 T1CKPS1:T1CKPS0: Timer1 Input Clock Prescale Select bits
11= 1:8 Prescale value
10= 1:4 Prescale value
01= 1:2 Prescale value
00= 1:1 Prescale value
bit 3
bit 2
T1OSCEN: Timer1 Oscillator Enable bit
1= Timer1 oscillator is enabled
0= Timer1 oscillator is shut off
The oscillator inverter and feedback resistor are turned off to eliminate power drain.
T1SYNC: Timer1 External Clock Input Synchronization Select bit
When TMR1CS = 1:
1= Do not synchronize external clock input
0= Synchronize external clock input
When TMR1CS = 0:
This bit is ignored. Timer1 uses the internal clock when TMR1CS = 0.
bit 1
bit 0
TMR1CS: Timer1 Clock Source Select bit
1= External clock from pin RC0/T1OSO/T13CKI (on the rising edge)
0= Internal clock (FOSC/4)
TMR1ON: Timer1 On bit
1= Enables Timer1
0= Stops Timer1
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
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cycle (Fosc/4). When the bit is set, Timer1 increments
on every rising edge of the Timer1 external clock input
or the Timer1 oscillator, if enabled.
12.1 Timer1 Operation
Timer1 can operate in one of these modes:
• Timer
When Timer1 is enabled, the RC1/T1OSI and RC0/
T1OSO/T13CKI pins become inputs. This means the
values of TRISC<1:0> are ignored and the pins are
read as ‘0’.
• Synchronous Counter
• Asynchronous Counter
The operating mode is determined by the clock select
bit, TMR1CS (T1CON<1>). When TMR3CS is cleared
(= 0), Timer1 increments on every internal instruction
FIGURE 12-1:
TIMER1 BLOCK DIAGRAM
Timer1 Oscillator
Timer1 Clock Input
1
0
On/Off
T1OSO/T13CKI
T1OSI
1
Synchronize
Detect
Prescaler
1, 2, 4, 8
FOSC/4
Internal
Clock
0
2
Sleep Input
T1OSCEN(1)
T1CKPS1:T1CKPS0
T1SYNC
Timer1
On/Off
TMR1CS
TMR1ON
Set
TMR1
High Byte
Clear TMR1
(CCP Special Event Trigger)
TMR1L
TMR1IF
on Overflow
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
FIGURE 12-2:
TIMER1 BLOCK DIAGRAM (16-BIT READ/WRITE MODE)
Timer1 Oscillator
Timer1 Clock Input
1
0
T1OSO/T13CKI
T1OSI
1
0
Synchronize
Detect
Prescaler
1, 2, 4, 8
FOSC/4
Internal
Clock
2
Sleep Input
T1OSCEN(1)
T1CKPS1:T1CKPS0
T1SYNC
Timer1
On/Off
TMR1CS
TMR1ON
Set
TMR1
High Byte
Clear TMR1
(CCP Special Event Trigger)
TMR1L
TMR1IF
on Overflow
8
Read TMR1L
Write TMR1L
8
8
TMR1H
8
8
Internal Data Bus
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
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TABLE 12-1: CAPACITOR SELECTION FOR
THE TIMER OSCILLATOR
12.2 Timer1 16-Bit Read/Write Mode
Timer1 can be configured for 16-bit reads and writes
(see Figure 12-2). When the RD16 control bit
(T1CON<7>) is set, the address for TMR1H is mapped
to a buffer register for the high byte of Timer1. A read
from TMR1L will load the contents of the high byte of
Timer1 into the Timer1 high byte buffer. This provides
the user with the ability to accurately read all 16 bits of
Timer1 without having to determine whether a read of
the high byte, followed by a read of the low byte, has
become invalid due to a rollover between reads.
Osc Type
Freq
C1
C2
LP
32 kHz
27 pF(1)
27 pF(1)
Note 1: Microchip suggests these values as a
starting point in validating the oscillator
circuit.
2: Higher capacitance increases the stability
of the oscillator but also increases the
start-up time.
A write to the high byte of Timer1 must also take place
through the TMR1H Buffer register. The Timer1 high
byte is updated with the contents of TMR1H when a
write occurs to TMR1L. This allows a user to write all
16 bits to both the high and low bytes of Timer1 at once.
3: Since each resonator/crystal has its own
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate
values
of
external
components.
The high byte of Timer1 is not directly readable or
writable in this mode. All reads and writes must take
place through the Timer1 High Byte Buffer register.
Writes to TMR1H do not clear the Timer1 prescaler.
The prescaler is only cleared on writes to TMR1L.
4: Capacitor values are for design guidance
only.
12.3.1
USING TIMER1 AS A
CLOCK SOURCE
The Timer1 oscillator is also available as a clock source
in power managed modes. By setting the clock select
bits, SCS1:SCS0 (OSCCON<1:0>), to ‘01’, the device
switches to SEC_RUN mode; both the CPU and
peripherals are clocked from the Timer1 oscillator. If the
IDLEN bit (OSCCON<7>) is cleared and a SLEEP
instruction is executed, the device enters SEC_IDLE
mode. Additional details are available in Section 3.0
“Power Managed Modes”.
12.3 Timer1 Oscillator
An on-chip crystal oscillator circuit is incorporated
between pins T1OSI (input) and T1OSO (amplifier out-
put). It is enabled by setting the Timer1 Oscillator Enable
bit, T1OSCEN (T1CON<3>). The oscillator is a low-
power circuit rated for 32 kHz crystals. It will continue to
run during all power managed modes. The circuit for a
typical LP oscillator is shown in Figure 12-3. Table 12-1
shows the capacitor selection for the Timer1 oscillator.
Whenever the Timer1 oscillator is providing the clock
source, the Timer1 system clock status flag, T1RUN
(T1CON<6>), is set. This can be used to determine the
controller’s current clocking mode. It can also indicate
the clock source being currently used by the Fail-Safe
Clock Monitor. If the Clock Monitor is enabled and the
Timer1 oscillator fails while providing the clock, polling
the T1RUN bit will indicate whether the clock is being
provided by the Timer1 oscillator or another source.
The user must provide a software time delay to ensure
proper start-up of the Timer1 oscillator.
FIGURE 12-3:
EXTERNAL
COMPONENTS FOR THE
TIMER1 LP OSCILLATOR
C1
27 pF
PIC18FXXXX
T1OSI
12.3.2
LOW-POWER TIMER1 OPTION
The Timer1 oscillator can operate at two distinct levels
of power consumption based on device configuration.
When the LPT1OSC configuration bit is set, the Timer1
oscillator operates in a low-power mode. When
LPT1OSC is not set, Timer1 operates at a higher power
level. Power consumption for a particular mode is rela-
tively constant, regardless of the device’s operating
mode. The default Timer1 configuration is the higher
power mode.
XTAL
32.768 kHz
T1OSO
C2
27 pF
Note:
See the Notes with Table 12-1 for additional
information about capacitor selection.
As the low-power Timer1 mode tends to be more sen-
sitive to interference, high noise environments may
cause some oscillator instability. The low-power option
is, therefore, best suited for low noise applications
where power conservation is an important design
consideration.
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12.3.3
TIMER1 OSCILLATOR LAYOUT
CONSIDERATIONS
12.5 Resetting Timer1 Using the CCP
Special Event Trigger
The Timer1 oscillator circuit draws very little power
during operation. Due to the low-power nature of the
oscillator, it may also be sensitive to rapidly changing
signals in close proximity.
If either of the CCP modules is configured to use Timer1
and generate a Special Event Trigger in Compare mode
(CCP1M3:CCP1M0 or CCP2M3:CCP2M0 = 1011), this
signal will reset Timer1. The trigger from CCP2 will also
start an A/D conversion if the A/D module is enabled
(see Section 15.3.4 “Special Event Trigger” for more
information).
The oscillator circuit, shown in Figure 12-3, should be
located as close as possible to the microcontroller.
There should be no circuits passing within the oscillator
circuit boundaries other than VSS or VDD.
The module must be configured as either a timer or a
synchronous counter to take advantage of this feature.
When used this way, the CCPRH:CCPRL register pair
effectively becomes a period register for Timer1.
If a high-speed circuit must be located near the oscilla-
tor (such as the CCP1 pin in Output Compare or PWM
mode, or the primary oscillator using the OSC2 pin), a
grounded guard ring around the oscillator circuit, as
shown in Figure 12-4, may be helpful when used on a
single-sided PCB or in addition to a ground plane.
If Timer1 is running in Asynchronous Counter mode,
this Reset operation may not work.
In the event that a write to Timer1 coincides with a
special Event Trigger, the write operation will take
precedence.
FIGURE 12-4:
OSCILLATOR CIRCUIT
WITH GROUNDED
GUARD RING
Note:
The Special Event Triggers from the
CCP2 module will not set the TMR1IF
interrupt flag bit (PIR1<0>).
VDD
VSS
12.6 Using Timer1 as a Real-Time Clock
OSC1
OSC2
Adding an external LP oscillator to Timer1 (such as the
one described in Section 12.3 “Timer1 Oscillator”
above) gives users the option to include RTC function-
ality to their applications. This is accomplished with an
inexpensive watch crystal to provide an accurate time
base and several lines of application code to calculate
the time. When operating in Sleep mode and using a
battery or supercapacitor as a power source, it can
completely eliminate the need for a separate RTC
device and battery backup.
RC0
RC1
RC2
The application code routine, RTCisr, shown in
Example 12-1, demonstrates a simple method to
increment a counter at one-second intervals using an
Interrupt Service Routine. Incrementing the TMR1 reg-
ister pair to overflow triggers the interrupt and calls the
routine, which increments the seconds counter by one;
additional counters for minutes and hours are
incremented as the previous counter overflow.
Note: Not drawn to scale.
12.4 Timer1 Interrupt
The TMR1 register pair (TMR1H:TMR1L) increments
from 0000h to FFFFh and rolls over to 0000h. The
Timer1 interrupt, if enabled, is generated on overflow,
which is latched in interrupt flag bit, TMR1IF
(PIR1<0>). This interrupt can be enabled or disabled
by setting or clearing the Timer1 Interrupt Enable bit,
TMR1IE (PIE1<0>).
Since the register pair is 16 bits wide, counting up to
overflow the register directly from a 32.768 kHz clock
would take 2 seconds. To force the overflow at the
required one-second intervals, it is necessary to pre-
load it; the simplest method is to set the MSb of TMR1H
with a BSFinstruction. Note that the TMR1L register is
never preloaded or altered; doing so may introduce
cumulative error over many cycles.
For this method to be accurate, Timer1 must operate in
Asynchronous mode and the Timer1 overflow interrupt
must be enabled (PIE1<0> = 1), as shown in the
routine, RTCinit. The Timer1 oscillator must also be
enabled and running at all times.
DS39631A-page 130
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EXAMPLE 12-1:
IMPLEMENTING A REAL-TIME CLOCK USING A TIMER1 INTERRUPT SERVICE
RTCinit
MOVLW
MOVWF
CLRF
80h
TMR1H
TMR1L
; Preload TMR1 register pair
; for 1 second overflow
MOVLW
MOVWF
CLRF
b’00001111’
T1CON
secs
; Configure for external clock,
; Asynchronous operation, external oscillator
; Initialize timekeeping registers
;
CLRF
mins
MOVLW
MOVWF
BSF
.12
hours
PIE1, TMR1IE
; Enable Timer1 interrupt
RETURN
RTCisr
BSF
BCF
INCF
MOVLW
CPFSGT
RETURN
CLRF
TMR1H, 7
PIR1, TMR1IF
secs, F
.59
; Preload for 1 sec overflow
; Clear interrupt flag
; Increment seconds
; 60 seconds elapsed?
secs
; No, done
secs
mins, F
.59
; Clear seconds
; Increment minutes
; 60 minutes elapsed?
INCF
MOVLW
CPFSGT
RETURN
CLRF
mins
; No, done
mins
hours, F
.23
; clear minutes
; Increment hours
; 24 hours elapsed?
INCF
MOVLW
CPFSGT
RETURN
CLRF
hours
; No, done
; Reset hours
; Done
hours
RETURN
TABLE 12-2: REGISTERS ASSOCIATED WITH TIMER1 AS A TIMER/COUNTER
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
PIR1
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
TXIF
RBIE
SSPIF
SSPIE
SSPIP
TMR0IF
CCP1IF
CCP1IE
CCP1IP
INT0IF
TMR2IF
TMR2IE
TMR2IP
RBIF
49
52
52
52
50
50
50
PSPIF(1)
PSPIE(1)
PSPIP(1)
ADIF
ADIE
ADIP
RCIF
RCIE
RCIP
TMR1IF
TMR1IE
TMR1IP
PIE1
TXIE
TXIP
IPR1
TMR1L
TMR1H
T1CON
Timer1 Register, Low Byte
Timer1 Register, High Byte
RD16
T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON
Legend: Shaded cells are not used by the Timer1 module.
Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear.
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NOTES:
DS39631A-page 132
Preliminary
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13.1 Timer2 Operation
13.0 TIMER2 MODULE
In normal operation, TMR2 is incremented from 00h on
each clock (FOSC/4). A 4-bit counter/prescaler on the
clock input gives direct input, divide-by-4 and divide-by-
16 prescale options; these are selected by the prescaler
control bits, T2CKPS1:T2CKPS0 (T2CON<1:0>). The
value of TMR2 is compared to that of the period register,
PR2, on each clock cycle. When the two values match,
the comparator generates a match signal as the timer
output. This signal also resets the value of TMR2 to 00h
on the next cycle and drives the output counter/
postscaler (see Section 13.2 “Timer2 Interrupt”).
The Timer2 module timer incorporates the following
features:
• 8-bit timer and period registers (TMR2 and PR2,
respectively)
• Readable and writable (both registers)
• Software programmable prescaler (1:1, 1:4 and
1:16)
• Software programmable postscaler (1:1 through
1:16)
• Interrupt on TMR2-to-PR2 match
• Optional use as the shift clock for the MSSP
module
The TMR2 and PR2 registers are both directly readable
and writable. The TMR2 register is cleared on any
device Reset, while the PR2 register initializes at FFh.
Both the prescaler and postscaler counters are cleared
on the following events:
The module is controlled through the T2CON register
(Register 13-1), which enables or disables the timer
and configures the prescaler and postscaler. Timer2
can be shut off by clearing control bit, TMR2ON
(T2CON<2>), to minimize power consumption.
• a write to the TMR2 register
• a write to the T2CON register
A simplified block diagram of the module is shown in
Figure 13-1.
• any device Reset (Power-on Reset, MCLR Reset,
Watchdog Timer Reset or Brown-out Reset)
TMR2 is not cleared when T2CON is written.
REGISTER 13-1: T2CON: TIMER2 CONTROL REGISTER
U-0
—
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0
bit 0
bit 7
bit 7
Unimplemented: Read as ‘0’
bit 6-3 T2OUTPS3:T2OUTPS0: Timer2 Output Postscale Select bits
0000= 1:1 Postscale
0001= 1:2 Postscale
•
•
•
1111= 1:16 Postscale
bit 2
TMR2ON: Timer2 On bit
1= Timer2 is on
0= Timer2 is off
bit 1-0 T2CKPS1:T2CKPS0: Timer2 Clock Prescale Select bits
00= Prescaler is 1
01= Prescaler is 4
1x= Prescaler is 16
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
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13.2 Timer2 Interrupt
13.3 Timer2 Output
Timer2 also can generate an optional device interrupt.
The Timer2 output signal (TMR2-to-PR2 match) pro-
vides the input for the 4-bit output counter/postscaler.
This counter generates the TMR2 match interrupt flag
which is latched in TMR2IF (PIR1<1>). The interrupt is
enabled by setting the TMR2 Match Interrupt Enable
bit, TMR2IE (PIE1<1>).
The unscaled output of TMR2 is available primarily to
the CCP modules, where it is used as a time base for
operations in PWM mode.
Timer2 can be optionally used as the shift clock source
for the MSSP module operating in SPI mode. Addi-
tional information is provided in Section 17.0 “Master
Synchronous Serial Port (MSSP) Module”.
A range of 16 postscale options (from 1:1 through 1:16
inclusive) can be selected with the postscaler control
bits, T2OUTPS3:T2OUTPS0 (T2CON<6:3>).
FIGURE 13-1:
TIMER2 BLOCK DIAGRAM
4
1:1 to 1:16
Set TMR2IF
Postscaler
T2OUTPS3:T2OUTPS0
2
TMR2 Output
T2CKPS1:T2CKPS0
(to PWM or MSSP)
TMR2/PR2
Match
Reset
TMR2
1:1, 1:4, 1:16
Prescaler
PR2
FOSC/4
Comparator
8
8
8
Internal Data Bus
TABLE 13-1: REGISTERS ASSOCIATED WITH TIMER2 AS A TIMER/COUNTER
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
TXIF
RBIE
SSPIF
SSPIE
SSPIP
TMR0IF
CCP1IF
CCP1IE
CCP1IP
INT0IF
TMR2IF
TMR2IE
TMR2IP
RBIF
49
52
52
52
50
50
50
PIR1
PSPIF(1)
PSPIE(1)
PSPIP(1)
ADIF
ADIE
ADIP
RCIF
RCIE
RCIP
TMR1IF
TMR1IE
TMR1IP
PIE1
TXIE
TXIP
IPR1
TMR2
T2CON
PR2
Timer2 Register
T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0
Timer2 Period Register
—
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Timer2 module.
Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear.
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A simplified block diagram of the Timer3 module is
shown in Figure 14-1. A block diagram of the module’s
operation in Read/Write mode is shown in Figure 14-2.
14.0 TIMER3 MODULE
The Timer3 module timer/counter incorporates these
features:
The Timer3 module is controlled through the T3CON
register (Register 14-1). It also selects the clock source
options for the CCP modules (see Section 15.1.1
“CCP Modules and Timer Resources” for more
information).
• Software selectable operation as a 16-bit timer or
counter
• Readable and writable 8-bit registers (TMR3H
and TMR3L)
• Selectable clock source (internal or external) with
device clock or Timer1 oscillator internal options
• Interrupt-on-overflow
• Module Reset on CCP Special Event Trigger
REGISTER 14-1: T3CON: TIMER3 CONTROL REGISTER
R/W-0
RD16
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
T3CCP2 T3CKPS1 T3CKPS0 T3CCP1 T3SYNC TMR3CS TMR3ON
bit 0
bit 7
bit 7
RD16: 16-bit Read/Write Mode Enable bit
1= Enables register read/write of Timer3 in one 16-bit operation
0= Enables register read/write of Timer3 in two 8-bit operations
bit 6,3 T3CCP2:T3CCP1: Timer3 and Timer1 to CCPx Enable bits
1x= Timer3 is the capture/compare clock source for the CCP modules
01= Timer3 is the capture/compare clock source for CCP2;
Timer1 is the capture/compare clock source for CCP1
00= Timer1 is the capture/compare clock source for the CCP modules
bit 5-4 T3CKPS1:T3CKPS0: Timer3 Input Clock Prescale Select bits
11= 1:8 Prescale value
10= 1:4 Prescale value
01= 1:2 Prescale value
00= 1:1 Prescale value
bit 2
T3SYNC: Timer3 External Clock Input Synchronization Control bit
(Not usable if the device clock comes from Timer1/Timer3.)
When TMR3CS = 1:
1= Do not synchronize external clock input
0= Synchronize external clock input
When TMR3CS = 0:
This bit is ignored. Timer3 uses the internal clock when TMR3CS = 0.
bit 1
bit 0
TMR3CS: Timer3 Clock Source Select bit
1= External clock input from Timer1 oscillator or T13CKI (on the rising edge after the first
falling edge)
0= Internal clock (FOSC/4)
TMR3ON: Timer3 On bit
1= Enables Timer3
0= Stops Timer3
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 135
PIC18F2420/2520/4420/4520
The operating mode is determined by the clock select
14.1 Timer3 Operation
bit, TMR3CS (T3CON<1>). When TMR3CS is cleared
(= 0), Timer3 increments on every internal instruction
cycle (FOSC/4). When the bit is set, Timer3 increments
on every rising edge of the Timer1 external clock input
or the Timer1 oscillator, if enabled.
Timer3 can operate in one of three modes:
• Timer
• Synchronous Counter
• Asynchronous Counter
As with Timer1, the RC1/T1OSI and RC0/T1OSO/
T13CKI pins become inputs when the Timer1 oscillator
is enabled. This means the values of TRISC<1:0> are
ignored and the pins are read as ‘0’.
FIGURE 14-1:
TIMER3 BLOCK DIAGRAM
Timer1 Oscillator
Timer1 Clock Input
1
0
T1OSO/T13CKI
T1OSI
1
0
Synchronize
Detect
Prescaler
1, 2, 4, 8
FOSC/4
Internal
Clock
2
Sleep Input
T1OSCEN(1)
T3CKPS1:T3CKPS0
T3SYNC
Timer3
On/Off
TMR3CS
TMR3ON
CCP1/CCP2 Special Event Trigger
CCP1/CCP2 Select from T3CON<6,3>
Clear TMR3
Set
TMR3
High Byte
TMR3L
TMR3IF
on Overflow
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
FIGURE 14-2:
TIMER3 BLOCK DIAGRAM (16-BIT READ/WRITE MODE)
Timer1 Oscillator
Timer1 Clock Input
1
0
T13CKI/T1OSO
T1OSI
1
0
Synchronize
Detect
Prescaler
1, 2, 4, 8
FOSC/4
Internal
Clock
2
Sleep Input
T1OSCEN(1)
T3CKPS1:T3CKPS0
T3SYNC
Timer3
On/Off
TMR3CS
TMR3ON
CCP1/CCP2 Special Event Trigger
CCP1/CCP2 Select from T3CON<6,3>
Clear TMR3
Set
TMR3
High Byte
TMR3L
TMR3IF
on Overflow
8
Read TMR1L
Write TMR1L
8
8
TMR3H
8
8
Internal Data Bus
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
DS39631A-page 136
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
14.2 Timer3 16-Bit Read/Write Mode
14.4 Timer3 Interrupt
Timer3 can be configured for 16-bit reads and writes
(see Figure 14-2). When the RD16 control bit
(T3CON<7>) is set, the address for TMR3H is mapped
to a buffer register for the high byte of Timer3. A read
from TMR3L will load the contents of the high byte of
Timer3 into the Timer3 High Byte Buffer register. This
provides the user with the ability to accurately read all
16 bits of Timer1 without having to determine whether
a read of the high byte, followed by a read of the low
byte, has become invalid due to a rollover between
reads.
The TMR3 register pair (TMR3H:TMR3L) increments
from 0000h to FFFFh and overflows to 0000h. The
Timer3 interrupt, if enabled, is generated on overflow
and is latched in interrupt flag bit, TMR3IF (PIR2<1>).
This interrupt can be enabled or disabled by setting or
clearing the Timer3 Interrupt Enable bit, TMR3IE
(PIE2<1>).
14.5 Resetting Timer3 Using the CCP
Special Event Trigger
If either of the CCP modules is configured to use
Timer3 and to generate a Special Event Trigger
A write to the high byte of Timer3 must also take place
through the TMR3H Buffer register. The Timer3 high
byte is updated with the contents of TMR3H when a
write occurs to TMR3L. This allows a user to write all
16 bits to both the high and low bytes of Timer3 at once.
in Compare
mode
(CCP1M3:CCP1M0
or
CCP2M3:CCP2M0 = 1011), this signal will reset
Timer3. It will also start an A/D conversion if the A/D
module is enabled (see Section 15.3.4 “Special
Event Trigger” for more information).
The high byte of Timer3 is not directly readable or
writable in this mode. All reads and writes must take
place through the Timer3 High Byte Buffer register.
The module must be configured as either a timer or
synchronous counter to take advantage of this feature.
When used this way, the CCPR2H:CCPR2L register
pair effectively becomes a period register for Timer3.
Writes to TMR3H do not clear the Timer3 prescaler.
The prescaler is only cleared on writes to TMR3L.
If Timer3 is running in Asynchronous Counter mode,
the Reset operation may not work.
14.3 Using the Timer1 Oscillator as the
Timer3 Clock Source
In the event that a write to Timer3 coincides with a
Special Event Trigger from a CCP module, the write will
take precedence.
The Timer1 internal oscillator may be used as the clock
source for Timer3. The Timer1 oscillator is enabled by
setting the T1OSCEN (T1CON<3>) bit. To use it as the
Timer3 clock source, the TMR3CS bit must also be set.
As previously noted, this also configures Timer3 to
increment on every rising edge of the oscillator source.
Note:
The Special Event Triggers from the
CCP2 module will not set the TMR3IF
interrupt flag bit (PIR1<0>).
The Timer1 oscillator is described in Section 12.0
“Timer1 Module”.
TABLE 14-1: REGISTERS ASSOCIATED WITH TIMER3 AS A TIMER/COUNTER
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
PIR2
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
EEIF
RBIE
BCLIF
BCLIE
BCLIP
TMR0IF
HLVDIF
HLVDIE
HLVDIP
INT0IF
TMR3IF
TMR3IE
TMR3IP
RBIF
49
52
52
52
51
51
50
51
OSCFIF
OSCFIE
OSCFIP
CMIF
CMIE
CMIP
—
—
—
CCP2IF
CCP2IE
CCP2IP
PIE2
EEIE
EEIP
IPR2
TMR3L
TMR3H
T1CON
T3CON
Timer3 Register, Low Byte
Timer3 Register, High Byte
RD16
RD16
T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON
T3CCP2 T3CKPS1 T3CKPS0 T3CCP1 T3SYNC TMR3CS TMR3ON
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Timer3 module.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 137
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 138
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
The Capture and Compare operations described in this
chapter apply to all standard and enhanced CCP
modules.
15.0 CAPTURE/COMPARE/PWM
(CCP) MODULES
PIC18F2420/2520/4420/4520 devices all have two
CCP (Capture/Compare/PWM) modules. Each module
contains a 16-bit register which can operate as a 16-bit
Capture register, a 16-bit Compare register or a PWM
Master/Slave Duty Cycle register.
Note: Throughout this section and Section 16.0
“Enhanced Capture/Compare/PWM (ECCP)
Module”, references to the register and bit
names for CCP modules are referred to gener-
ically by the use of ‘x’ or ‘y’ in place of the
specific module number. Thus, “CCPxCON”
might refer to the control register for CCP1,
CCP2 or ECCP1. “CCPxCON” is used
throughout these sections to refer to the mod-
ule control register, regardless of whether the
CCP module is a standard or enhanced
implementation.
In 28-pin devices, the two standard CCP modules (CCP1
and CCP2) operate as described in this chapter. In 40/
44-pin devices, CCP1 is implemented as an enhanced
CCP module with standard Capture and Compare
modes and enhanced PWM modes. The ECCP imple-
mentation is discussed in Section 16.0 “Enhanced
Capture/Compare/PWM (ECCP) Module”.
REGISTER 15-1: CCPXCON REGISTER (CCP2 MODULE, CCP1 MODULE IN 28-PIN DEVICES)
U-0
—
U-0
—
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
DCxB1
DCxB0
CCPxM3 CCPxM2 CCPxM1 CCPxM0
bit 0
bit 7
bit 7-6 Unimplemented: Read as ‘0’
bit 5-4 DCxB1:DCxB0: PWM Duty Cycle bit 1 and bit 0 for CCP Module x
Capture mode:
Unused.
Compare mode:
Unused.
PWM mode:
These bits are the two LSbs (bit 1 and bit 0) of the 10-bit PWM duty cycle. The eight MSbs
(DCx9:DCx2) of the duty cycle are found in CCPRxL.
bit 3-0 CCPxM3:CCPxM0: CCP Module x Mode Select bits
0000= Capture/Compare/PWM disabled (resets CCP module)
0001= Reserved
0010= Compare mode, toggle output on match (CCPxIF bit is set)
0011= Reserved
0100= Capture mode, every falling edge
0101= Capture mode, every rising edge
0110= Capture mode, every 4th rising edge
0111= Capture mode, every 16th rising edge
1000= Compare mode: initialize CCP pin low; on compare match, force CCP pin high
(CCPIF bit is set)
1001= Compare mode: initialize CCP pin high; on compare match, force CCP pin low
(CCPIF bit is set)
1010= Compare mode: generate software interrupt on compare match (CCPxIF bit is set,
CCP pin reflects I/O state)
1011= Compare mode: trigger special event, reset timer, start A/D conversion on
CCP2 match (CCPxIF bit is set)
11xx= PWM mode
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 139
PIC18F2420/2520/4420/4520
The assignment of a particular timer to a module is
15.1 CCP Module Configuration
determined by the Timer-to-CCP enable bits in the
T3CON register (Register 14-1). Both modules may be
active at any given time and may share the same timer
resource if they are configured to operate in the same
mode (Capture/Compare or PWM) at the same time. The
interactions between the two modules are summarized in
Figure 15-1 and Figure 15-2. In Timer1 in Asynchronous
Counter mode, the capture operation will not work.
Each Capture/Compare/PWM module is associated
with a control register (generically, CCPxCON) and a
data register (CCPRx). The data register, in turn, is
comprised of two 8-bit registers: CCPRxL (low byte)
and CCPRxH (high byte). All registers are both
readable and writable.
15.1.1
CCP MODULES AND TIMER
RESOURCES
15.1.2
CCP2 PIN ASSIGNMENT
The CCP modules utilize Timers 1, 2 or 3, depending
on the mode selected. Timer1 and Timer3 are available
to modules in Capture or Compare modes, while
Timer2 is available for modules in PWM mode.
The pin assignment for CCP2 (Capture input, Compare
and PWM output) can change, based on device config-
uration. The CCP2MX configuration bit determines
which pin CCP2 is multiplexed to. By default, it is
assigned to RC1 (CCP2MX = 1). If the configuration bit
is cleared, CCP2 is multiplexed with RB3.
TABLE 15-1: CCP MODE – TIMER
RESOURCE
Changing the pin assignment of CCP2 does not auto-
matically change any requirements for configuring the
port pin. Users must always verify that the appropriate
TRIS register is configured correctly for CCP2
operation, regardless of where it is located.
CCP/ECCP Mode
Timer Resource
Capture
Compare
PWM
Timer1 or Timer3
Timer1 or Timer3
Timer2
TABLE 15-2: INTERACTIONS BETWEEN CCP1 AND CCP2 FOR TIMER RESOURCES
CCP1 Mode CCP2 Mode
Interaction
Capture
Capture
Each module can use TMR1 or TMR3 as the time base. The time base can be different
for each CCP.
Capture
Compare CCP2 can be configured for the Special Event Trigger to reset TMR1 or TMR3
(depending upon which time base is used). Automatic A/D conversions on trigger event
can also be done. Operation of CCP1 could be affected if it is using the same timer as a
time base.
Compare
Compare
Capture
CCP1 can be configured for the Special Event Trigger to reset TMR1 or TMR3
(depending upon which time base is used). Operation of CCP2 could be affected if it is
using the same timer as a time base.
Compare Either module can be configured for the Special Event Trigger to reset the time base.
Automatic A/D conversions on CCP2 trigger event can be done. Conflicts may occur if
both modules are using the same time base.
Capture
Compare
PWM(1)
PWM(1)
PWM(1)
PWM(1)
PWM(1)
Capture
None
None
None
Compare None
PWM Both PWMs will have the same frequency and update rate (TMR2 interrupt).
Note 1: Includes standard and enhanced PWM operation.
DS39631A-page 140
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
15.2.3
SOFTWARE INTERRUPT
15.2 Capture Mode
When the Capture mode is changed, a false capture
interrupt may be generated. The user should keep the
CCPxIE interrupt enable bit clear to avoid false inter-
rupts. The interrupt flag bit, CCPxIF, should also be
cleared following any such change in operating mode.
In Capture mode, the CCPRxH:CCPRxL register pair
captures the 16-bit value of the TMR1 or TMR3
registers when an event occurs on the corresponding
CCPx pin. An event is defined as one of the following:
• every falling edge
• every rising edge
15.2.4
CCP PRESCALER
• every 4th rising edge
• every 16th rising edge
There are four prescaler settings in Capture mode; they
are specified as part of the operating mode selected by
the mode select bits (CCPxM3:CCPxM0). Whenever
the CCP module is turned off or Capture mode is
disabled, the prescaler counter is cleared. This means
that any Reset will clear the prescaler counter.
The event is selected by the mode select bits,
CCPxM3:CCPxM0 (CCPxCON<3:0>). When a capture
is made, the interrupt request flag bit, CCPxIF, is set; it
must be cleared in software. If another capture occurs
before the value in register CCPRx is read, the old
captured value is overwritten by the new captured value.
Switching from one capture prescaler to another may
generate an interrupt. Also, the prescaler counter will
not be cleared; therefore, the first capture may be from
15.2.1
CCP PIN CONFIGURATION
a
non-zero prescaler. Example 15-1 shows the
recommended method for switching between capture
prescalers. This example also clears the prescaler
counter and will not generate the “false” interrupt.
In Capture mode, the appropriate CCPx pin should be
configured as an input by setting the corresponding
TRIS direction bit.
Note:
If RB3/CCP2 or RC1/CCP2 is configured
as an output, a write to the port can cause
a capture condition.
EXAMPLE 15-1:
CHANGING BETWEEN
CAPTURE PRESCALERS
(CCP2 SHOWN)
CLRF
CCP2CON
; Turn CCP module off
15.2.2
TIMER1/TIMER3 MODE SELECTION
MOVLW NEW_CAPT_PS ; Load WREG with the
; new prescaler mode
The timers that are to be used with the capture feature
(Timer1 and/or Timer3) must be running in Timer mode or
Synchronized Counter mode. In Asynchronous Counter
mode, the capture operation will not work. The timer to be
used with each CCP module is selected in the T3CON
register (see Section 15.1.1 “CCP Modules and Timer
Resources”).
; value and CCP ON
; Load CCP2CON with
; this value
MOVWF CCP2CON
FIGURE 15-1:
CAPTURE MODE OPERATION BLOCK DIAGRAM
TMR3H
TMR3
TMR3L
Set CCP1IF
T3CCP2
Enable
CCP1 pin
Prescaler
÷ 1, 4, 16
and
Edge Detect
CCPR1H
CCPR1L
TMR1
Enable
T3CCP2
TMR1H
TMR3H
TMR1L
TMR3L
4
4
CCP1CON<3:0>
Q1:Q4
Set CCP2IF
4
CCP2CON<3:0>
T3CCP1
T3CCP2
TMR3
Enable
CCP2 pin
Prescaler
÷ 1, 4, 16
and
Edge Detect
CCPR2H
CCPR2L
TMR1L
TMR1
Enable
T3CCP2
T3CCP1
TMR1H
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 141
PIC18F2420/2520/4420/4520
15.3.2
TIMER1/TIMER3 MODE SELECTION
15.3 Compare Mode
Timer1 and/or Timer3 must be running in Timer mode
or Synchronized Counter mode if the CCP module is
using the compare feature. In Asynchronous Counter
mode, the compare operation may not work.
In Compare mode, the 16-bit CCPRx register value is
constantly compared against either the TMR1 or TMR3
register pair value. When a match occurs, the CCPx pin
can be:
• driven high
15.3.3
SOFTWARE INTERRUPT MODE
• driven low
When the Generate Software Interrupt mode is chosen
(CCPxM3:CCPxM0 = 1010), the corresponding CCPx
pin is not affected. Only a CCP interrupt is generated,
if enabled and the CCPxIE bit is set.
• toggled (high-to-low or low-to-high)
• remain unchanged (that is, reflects the state of the
I/O latch)
The action on the pin is based on the value of the mode
select bits (CCPxM3:CCPxM0). At the same time, the
interrupt flag bit, CCPxIF, is set.
15.3.4
SPECIAL EVENT TRIGGER
Both CCP modules are equipped with a Special Event
Trigger. This is an internal hardware signal generated
in Compare mode to trigger actions by other modules.
The Special Event Trigger is enabled by selecting
the Compare Special Event Trigger mode
(CCPxM3:CCPxM0 = 1011).
15.3.1
CCP PIN CONFIGURATION
The user must configure the CCPx pin as an output by
clearing the appropriate TRIS bit.
Note:
Clearing the CCP2CON register will force
the RB3 or RC1 compare output latch
(depending on device configuration) to the
default low level. This is not the PORTB or
PORTC I/O data latch.
For either CCP module, the Special Event Trigger resets
the timer register pair for whichever timer resource is
currently assigned as the module’s time base. This
allows the CCPRx registers to serve as a programmable
period register for either timer.
The Special Event Trigger for CCP2 can also start an
A/D conversion. In order to do this, the A/D converter
must already be enabled.
FIGURE 15-2:
COMPARE MODE OPERATION BLOCK DIAGRAM
Special Event Trigger
(Timer1/Timer3 Reset)
Set CCP1IF
CCPR1H
CCPR1L
CCP1 pin
S
R
Q
Output
Logic
Compare
Match
Comparator
TRIS
Output Enable
4
CCP1CON<3:0>
TMR1H
TMR3H
TMR1L
TMR3L
0
0
1
1
Special Event Trigger
(Timer1/Timer3 Reset, A/D Trigger)
T3CCP1
T3CCP2
Set CCP2IF
CCP2 pin
S
R
Q
Compare
Match
Output
Logic
Comparator
TRIS
Output Enable
4
CCPR2H
CCPR2L
CCP2CON<3:0>
DS39631A-page 142
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 15-3: REGISTERS ASSOCIATED WITH CAPTURE, COMPARE, TIMER1 AND TIMER3
Reset
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Values
on page
INTCON
RCON
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
RI
RBIE
TO
TMR0IF
PD
INT0IF
POR
RBIF
BOR
49
48
52
52
52
52
52
52
52
52
50
50
50
51
51
51
51
51
51
51
51
51
IPEN
SBOREN
ADIF
—
RCIF
RCIE
RCIP
—
PIR1
PSPIF(1)
PSPIE(1)
PSPIP(1)
OSCFIF
OSCFIE
OSCFIP
TXIF
TXIE
TXIP
EEIF
EEIE
EEIP
SSPIF
SSPIE
SSPIP
BCLIF
BCLIE
BCLIP
CCP1IF
TMR2IF TMR1IF
PIE1
ADIE
CCP1IE TMR2IE TMR1IE
CCP1IP TMR2IP TMR1IP
IPR1
ADIP
PIR2
CMIF
CMIE
CMIP
HLVDIF
TMR3IF
CCP2IF
PIE2
—
HLVDIE TMR3IE CCP2IE
HLVDIP TMR3IP CCP2IP
IPR2
—
TRISB
PORTB Data Direction Control Register
PORTC Data Direction Control Register
Timer1 Register, Low Byte
TRISC
TMR1L
TMR1H
T1CON
TMR3H
TMR3L
T3CON
CCPR1L
CCPR1H
CCP1CON
CCPR2L
CCPR2H
CCP2CON
Timer1 Register, High Byte
RD16
T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON
Timer3 Register, High Byte
Timer3 Register, Low Byte
RD16
T3CCP2 T3CKPS1 T3CKPS0 T3CCP1 T3SYNC TMR3CS TMR3ON
Capture/Compare/PWM Register 1, Low Byte
Capture/Compare/PWM Register 1, High Byte
P1M1(1)
P1M0(1)
DC1B1
DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0
Capture/Compare/PWM Register 2, Low Byte
Capture/Compare/PWM Register 2, High Byte
—
—
DC2B1
DC2B0 CCP2M3 CCP2M2 CCP2M1 CCP2M0
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by Capture/Compare, Timer1 or Timer3.
Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 143
PIC18F2420/2520/4420/4520
15.4.1
PWM PERIOD
15.4 PWM Mode
The PWM period is specified by writing to the PR2
register. The PWM period can be calculated using the
following formula:
In Pulse Width Modulation (PWM) mode, the CCPx pin
produces up to a 10-bit resolution PWM output. Since
the CCP2 pin is multiplexed with a PORTB or PORTC
data latch, the appropriate TRIS bit must be cleared to
make the CCP2 pin an output.
EQUATION 15-1:
PWM Period = [(PR2) + 1] • 4 • TOSC •
(TMR2 Prescale Value)
Note:
Clearing the CCP2CON register will force
the RB3 or RC1 output latch (depending on
device configuration) to the default low
level. This is not the PORTB or PORTC I/O
data latch.
PWM frequency is defined as 1/[PWM period].
When TMR2 is equal to PR2, the following three events
occur on the next increment cycle:
Figure 15-3 shows a simplified block diagram of the
CCP module in PWM mode.
• TMR2 is cleared
For a step-by-step procedure on how to set up the CCP
module for PWM operation, see Section 15.4.4
“Setup for PWM Operation”.
• The CCPx pin is set (exception: if PWM duty
cycle = 0%, the CCPx pin will not be set)
• The PWM duty cycle is latched from CCPRxL into
CCPRxH
FIGURE 15-3:
SIMPLIFIED PWM BLOCK
DIAGRAM
Note:
The Timer2 postscalers (see Section 13.0
“Timer2 Module”) are not used in the
determination of the PWM frequency. The
postscaler could be used to have a servo
update rate at a different frequency than
the PWM output.
CCPxCON<5:4>
Duty Cycle Registers
CCPRxL
15.4.2
PWM DUTY CYCLE
CCPRxH (Slave)
Comparator
CCPx Output
The PWM duty cycle is specified by writing to the
CCPRxL register and to the CCPxCON<5:4> bits. Up
to 10-bit resolution is available. The CCPRxL contains
the eight MSbs and the CCPxCON<5:4> contains the
two LSbs. This 10-bit value is represented by
CCPRxL:CCPxCON<5:4>. The following equation is
used to calculate the PWM duty cycle in time:
Q
R
S
(Note 1)
TMR2
Corresponding
TRIS bit
Comparator
PR2
Clear Timer,
CCP1 pin and
latch D.C.
EQUATION 15-2:
PWM Duty Cycle = (CCPRXL:CCPXCON<5:4>) •
TOSC • (TMR2 Prescale Value)
Note 1: The 8-bit TMR2 value is concatenated with the 2-bit
internal Q clock, or 2 bits of the prescaler, to create the
10-bit time base.
CCPRxL and CCPxCON<5:4> can be written to at any
time, but the duty cycle value is not latched into
CCPRxH until after a match between PR2 and TMR2
occurs (i.e., the period is complete). In PWM mode,
CCPRxH is a read-only register.
A PWM output (Figure 15-4) has a time base (period)
and a time that the output stays high (duty cycle).
The frequency of the PWM is the inverse of the
period (1/period).
FIGURE 15-4:
PWM OUTPUT
Period
Duty Cycle
TMR2 = PR2
TMR2 = Duty Cycle
TMR2 = PR2
DS39631A-page 144
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
The CCPRxH register and a 2-bit internal latch are
EQUATION 15-3:
used to double-buffer the PWM duty cycle. This
double-buffering is essential for glitchless PWM
operation.
FOSC
---------------
log
FPWM
PWM Resolution (max)
= ----------------------------- b i t s
log(2)
When the CCPRxH and 2-bit latch match TMR2,
concatenated with an internal 2-bit Q clock or 2 bits of
the TMR2 prescaler, the CCPx pin is cleared.
Note:
If the PWM duty cycle value is longer than
the PWM period, the CCP2 pin will not be
cleared.
The maximum PWM resolution (bits) for a given PWM
frequency is given by the equation:
TABLE 15-4: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz
PWM Frequency
2.44 kHz
9.77 kHz
39.06 kHz 156.25 kHz 312.50 kHz 416.67 kHz
Timer Prescaler (1, 4, 16)
PR2 Value
16
FFh
10
4
1
1
3Fh
8
1
1Fh
7
1
FFh
10
FFh
10
17h
6.58
Maximum Resolution (bits)
15.4.3
PWM AUTO-SHUTDOWN
(CCP1 ONLY)
15.4.4
SETUP FOR PWM OPERATION
The following steps should be taken when configuring
the CCP module for PWM operation:
The PWM auto-shutdown features of the enhanced CCP
module are also available to CCP1 in 28-pin devices.
The operation of this feature is discussed in detail in
Section 16.4.7 “Enhanced PWM Auto-Shutdown”.
1. Set the PWM period by writing to the PR2
register.
2. Set the PWM duty cycle by writing to the
CCPRxL register and CCPxCON<5:4> bits.
Auto-shutdown features are not available for CCP2.
3. Make the CCPx pin an output by clearing the
appropriate TRIS bit.
4. Set the TMR2 prescale value, then enable
Timer2 by writing to T2CON.
5. Configure the CCPx module for PWM operation.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 145
PIC18F2420/2520/4420/4520
TABLE 15-5: REGISTERS ASSOCIATED WITH PWM AND TIMER2
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
RCON
PIR1
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
RI
RBIE
TO
TMR0IF
PD
INT0IF
POR
RBIF
BOR
49
48
52
52
52
52
52
50
50
50
51
51
51
51
51
51
51
51
IPEN
SBOREN
ADIF
—
PSPIF(1)
PSPIE(1)
PSPIP(1)
RCIF
RCIE
RCIP
TXIF
TXIE
TXIP
SSPIF
SSPIE
SSPIP
CCP1IF
TMR2IF
TMR1IF
TMR1IE
TMR1IP
PIE1
ADIE
CCP1IE TMR2IE
CCP1IP TMR2IP
IPR1
ADIP
TRISB
TRISC
TMR2
PR2
PORTB Data Direction Control Register
PORTC Data Direction Control Register
Timer2 Register
Timer2 Period Register
T2CON
CCPR1L
—
T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0
Capture/Compare/PWM Register 1, Low Byte
CCPR1H Capture/Compare/PWM Register 1, High Byte
CCP1CON P1M1(1) P1M0(1)
DC1B1 DC1B0
CCPR2L Capture/Compare/PWM Register 2, Low Byte
CCPR2H Capture/Compare/PWM Register 2, High Byte
CCP2CON DC2B1 DC2B0
ECCP1AS ECCPASE ECCPAS2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PSSBD1(1) PSSBD0(1)
PWM1CON PRSEN
PDC6(1) PDC5(1) PDC4(1) PDC3(1) PDC2(1) PDC1(1) PDC0(1)
CCP1M3 CCP1M2 CCP1M1 CCP1M0
CCP2M3 CCP2M2 CCP2M1 CCP2M0
—
—
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PWM or Timer2.
Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear.
DS39631A-page 146
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
enhanced features are discussed in detail in
Section 16.4 “Enhanced PWM Mode”. Capture,
Compare and single-output PWM functions of the
ECCP module are the same as described for the
standard CCP module.
16.0 ENHANCED CAPTURE/
COMPARE/PWM (ECCP)
MODULE
Note:
The ECCP module is implemented only in
40/44-pin devices.
The control register for the enhanced CCP module is
shown in Register 16-1. It differs from the CCPxCON
registers in PIC18F2420/2520 devices in that the two
Most Significant bits are implemented to control PWM
functionality.
In PIC18F4420/4520 devices, CCP1 is implemented
as a standard CCP module with enhanced PWM
capabilities. These include the provision for 2 or 4
output channels, user selectable polarity, dead-band
control and automatic shutdown and restart. The
REGISTER 16-1: CCP1CON REGISTER (ECCP1 MODULE, 40/44-PIN DEVICES)
R/W-0
P1M1
R/W-0
P1M0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
DC1B1
DC1B0
CCP1M3 CCP1M2 CCP1M1 CCP1M0
bit 0
bit 7
bit 7-6
P1M1:P1M0: Enhanced PWM Output Configuration bits
If CCP1M3:CCP1M2 = 00, 01, 10:
xx= P1A assigned as Capture/Compare input/output; P1B, P1C, P1D assigned as port pins
If CCP1M3:CCP1M2 = 11:
00= Single output: P1A modulated; P1B, P1C, P1D assigned as port pins
01= Full-bridge output forward: P1D modulated; P1A active; P1B, P1C inactive
10= Half-bridge output: P1A, P1B modulated with dead-band control; P1C, P1D assigned
as port pins
11= Full-bridge output reverse: P1B modulated; P1C active; P1A, P1D inactive
bit 5-4
DC1B1:DC1B0: PWM Duty Cycle bit 1 and bit 0
Capture mode:
Unused.
Compare mode:
Unused.
PWM mode:
These bits are the two LSbs of the 10-bit PWM duty cycle. The eight MSbs of the duty cycle are
found in CCPR1L.
bit 3-0
CCP1M3:CCP1M0: Enhanced CCP Mode Select bits
0000= Capture/Compare/PWM off (resets ECCP module)
0001= Reserved
0010= Compare mode, toggle output on match
0011= Capture mode
0100= Capture mode, every falling edge
0101= Capture mode, every rising edge
0110= Capture mode, every 4th rising edge
0111= Capture mode, every 16th rising edge
1000= Compare mode, initialize CCP1 pin low, set output on compare match (set CCP1IF)
1001= Compare mode, initialize CCP1 pin high, clear output on compare match (set CCP1IF)
1010= Compare mode, generate software interrupt only, CCP1 pin reverts to I/O state
1011= Compare mode, trigger special event (ECCP resets TMR1 or TMR3, sets CC1IF bit)
1100= PWM mode; P1A, P1C active-high; P1B, P1D active-high
1101= PWM mode; P1A, P1C active-high; P1B, P1D active-low
1110= PWM mode; P1A, P1C active-low; P1B, P1D active-high
1111= PWM mode; P1A, P1C active-low; P1B, P1D active-low
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 147
PIC18F2420/2520/4420/4520
In addition to the expanded range of modes available
16.2 Capture and Compare Modes
through the CCP1CON register and ECCP1AS
register, the ECCP module has an additional register
associated with Enhanced PWM operation and
auto-shutdown features. It is:
Except for the operation of the Special Event Trigger
discussed below, the Capture and Compare modes of
the ECCP module are identical in operation to that of
CCP2. These are discussed in detail in Section 15.2
“Capture Mode” and Section 15.3 “Compare
Mode”. No changes are required when moving
between 28-pin and 40/44-pin devices.
• PWM1CON (Dead-band delay)
16.1 ECCP Outputs and Configuration
The enhanced CCP module may have up to four PWM
outputs, depending on the selected operating mode.
These outputs, designated P1A through P1D, are
multiplexed with I/O pins on PORTC and PORTD. The
outputs that are active depend on the CCP operating
mode selected. The pin assignments are summarized
in Table 16-1.
16.2.1
SPECIAL EVENT TRIGGER
The Special Event Trigger output of ECCP1 resets the
TMR1 or TMR3 register pair, depending on which timer
resource is currently selected. This allows the CCPR1
register to effectively be a 16-bit programmable period
register for Timer1 or Timer3.
To configure the I/O pins as PWM outputs, the proper
PWM mode must be selected by setting the
P1M1:P1M0 and CCP1M3:CCP1M0 bits. The
appropriate TRISC and TRISD direction bits for the port
pins must also be set as outputs.
16.3 Standard PWM Mode
When configured in Single Output mode, the ECCP
module functions identically to the standard CCP
module in PWM mode, as described in Section 15.4
“PWM Mode”. This is also sometimes referred to as
“Compatible CCP” mode, as in Table 16-1.
16.1.1
ECCP MODULES AND TIMER
RESOURCES
Note:
When setting up single output PWM opera-
tions, users are free to use either of the pro-
cesses described in Section 15.4.4 “Setup
for PWM Operation” or Section 16.4.9
“Setup for PWM Operation”. The latter is
more generic and will work for either single
or multi-output PWM.
Like the standard CCP modules, the ECCP module can
utilize Timers 1, 2 or 3, depending on the mode
selected. Timer1 and Timer3 are available for modules
in Capture or Compare modes, while Timer2 is avail-
able for modules in PWM mode. Interactions between
the standard and enhanced CCP modules are identical
to those described for standard CCP modules.
Additional details on timer resources are provided in
Section 15.1.1
“CCP
Modules
and
Timer
Resources”.
TABLE 16-1: PIN ASSIGNMENTS FOR VARIOUS ECCP1 MODES
CCP1CON
ECCP Mode
RC2
RD5
RD6
RD7
Configuration
All 40/44-pin devices:
Compatible CCP
Dual PWM
00xx 11xx
10xx 11xx
x1xx 11xx
CCP1
P1A
RD5/PSP5
P1B
RD6/PSP6
RD6/PSP6
P1C
RD7/PSP7
RD7/PSP7
P1D
Quad PWM
P1A
P1B
Legend: x= Don’t care. Shaded cells indicate pin assignments not used by ECCP1 in a given mode.
DS39631A-page 148
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
16.4.1
PWM PERIOD
16.4 Enhanced PWM Mode
The PWM period is specified by writing to the PR2
register. The PWM period can be calculated using the
following equation.
The Enhanced PWM mode provides additional PWM
output options for a broader range of control applica-
tions. The module is a backward compatible version of
the standard CCP module and offers up to four outputs,
designated P1A through P1D. Users are also able to
select the polarity of the signal (either active-high or
active-low). The module’s output mode and polarity are
configured by setting the P1M1:P1M0 and
CCP1M3:CCP1M0 bits of the CCP1CON register.
EQUATION 16-1:
PWM Period = [(PR2) + 1] • 4 • TOSC •
(TMR2 Prescale Value)
PWM frequency is defined as 1/[PWM period]. When
TMR2 is equal to PR2, the following three events occur
on the next increment cycle:
Figure 16-1 shows a simplified block diagram of PWM
operation. All control registers are double-buffered and
are loaded at the beginning of a new PWM cycle (the
period boundary when Timer2 resets) in order to pre-
vent glitches on any of the outputs. The exception is the
PWM Delay register, PWM1CON, which is loaded at
either the duty cycle boundary or the period boundary
(whichever comes first). Because of the buffering, the
module waits until the assigned timer resets, instead of
starting immediately. This means that enhanced PWM
waveforms do not exactly match the standard PWM
waveforms, but are instead offset by one full instruction
cycle (4 TOSC).
• TMR2 is cleared
• The CCP1 pin is set (if PWM duty cycle = 0%, the
CCP1 pin will not be set)
• The PWM duty cycle is copied from CCPR1L into
CCPR1H
Note:
The Timer2 postscaler (see Section 13.0
“Timer2 Module”) is not used in the
determination of the PWM frequency. The
postscaler could be used to have a servo
update rate at a different frequency than
the PWM output.
As before, the user must manually configure the
appropriate TRIS bits for output.
FIGURE 16-1:
SIMPLIFIED BLOCK DIAGRAM OF THE ENHANCED PWM MODULE
CCP1CON<5:4>
P1M1<1:0>
CCP1M<3:0>
4
Duty Cycle Registers
2
CCPR1L
CCP1/P1A
CCP1/P1A
P1B
TRISx<x>
TRISx<x>
TRISx<x>
TRISx<x>
CCPR1H (Slave)
Comparator
P1B
Output
Controller
R
S
Q
P1C
P1C
P1D
(Note 1)
TMR2
P1D
Comparator
PR2
Clear Timer,
set CCP1 pin and
latch D.C.
PWM1CON
Note: The 8-bit TMR2 register is concatenated with the 2-bit internal Q clock, or 2 bits of the prescaler, to create the 10-bit
time base.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 149
PIC18F2420/2520/4420/4520
16.4.2
PWM DUTY CYCLE
EQUATION 16-3:
The PWM duty cycle is specified by writing to the
CCPR1L register and to the CCP1CON<5:4> bits. Up
to 10-bit resolution is available. The CCPR1L contains
the eight MSbs and the CCP1CON<5:4> contains the
two LSbs. This 10-bit value is represented by
CCPR1L:CCP1CON<5:4>. The PWM duty cycle is
calculated by the following equation.
FOSC
FPWM
log
(
)
bits
PWM Resolution (max) =
log(2)
Note:
If the PWM duty cycle value is longer than
the PWM period, the CCP1 pin will not be
cleared.
EQUATION 16-2:
PWM Duty Cycle = (CCPR1L:CCP1CON<5:4>) •
TOSC • (TMR2 Prescale Value)
16.4.3
PWM OUTPUT CONFIGURATIONS
The P1M1:P1M0 bits in the CCP1CON register allow
one of four configurations:
CCPR1L and CCP1CON<5:4> can be written to at any
time, but the duty cycle value is not copied into
CCPR1H until a match between PR2 and TMR2 occurs
(i.e., the period is complete). In PWM mode, CCPR1H
is a read-only register.
• Single Output
• Half-Bridge Output
• Full-Bridge Output, Forward mode
• Full-Bridge Output, Reverse mode
The CCPR1H register and a 2-bit internal latch are
used to double-buffer the PWM duty cycle. This
double-buffering is essential for glitchless PWM opera-
tion. When the CCPR1H and 2-bit latch match TMR2,
concatenated with an internal 2-bit Q clock or two bits
of the TMR2 prescaler, the CCP1 pin is cleared. The
maximum PWM resolution (bits) for a given PWM
frequency is given by the following equation.
The Single Output mode is the standard PWM mode
discussed in Section 16.4 “Enhanced PWM Mode”.
The Half-Bridge and Full-Bridge Output modes are
covered in detail in the sections that follow.
The general relationship of the outputs in all
configurations is summarized in Figure 16-2.
TABLE 16-2: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz
PWM Frequency
2.44 kHz
9.77 kHz
39.06 kHz 156.25 kHz 312.50 kHz 416.67 kHz
Timer Prescaler (1, 4, 16)
PR2 Value
16
FFh
10
4
1
1
3Fh
8
1
1Fh
7
1
FFh
10
FFh
10
17h
6.58
Maximum Resolution (bits)
DS39631A-page 150
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 16-2:
PWM OUTPUT RELATIONSHIPS (ACTIVE-HIGH STATE)
0
PR2 + 1
Duty
Cycle
SIGNAL
CCP1CON
<7:6>
Period
P1A Modulated
P1A Modulated
P1B Modulated
P1A Active
(Single Output)
00
10
(1)
(1)
Delay
Delay
(Half-Bridge)
P1B Inactive
P1C Inactive
P1D Modulated
P1A Inactive
P1B Modulated
P1C Active
(Full-Bridge,
Forward)
01
(Full-Bridge,
Reverse)
11
P1D Inactive
FIGURE 16-3:
PWM OUTPUT RELATIONSHIPS (ACTIVE-LOW STATE)
0
PR2 + 1
SIGNAL
CCP1CON
Duty
Cycle
<7:6>
Period
P1A Modulated
P1A Modulated
P1B Modulated
P1A Active
(Single Output)
00
10
(1)
(1)
Delay
Delay
(Half-Bridge)
P1B Inactive
P1C Inactive
P1D Modulated
P1A Inactive
P1B Modulated
P1C Active
(Full-Bridge,
Forward)
01
(Full-Bridge,
Reverse)
11
P1D Inactive
Relationships:
•
•
•
Period = 4 * TOSC * (PR2 + 1) * (TMR2 Prescale Value)
Duty Cycle = TOSC * (CCPR1L<7:0>:CCP1CON<5:4>) * (TMR2 Prescale Value)
Delay = 4 * TOSC * (PWM1CON<6:0>)
Note 1: Dead-band delay is programmed using the PWM1CON register (see Section 16.4.6 “Programmable
Dead-Band Delay”).
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 151
PIC18F2420/2520/4420/4520
16.4.4
HALF-BRIDGE MODE
FIGURE 16-4:
HALF-BRIDGE PWM
OUTPUT
In the Half-Bridge Output mode, two pins are used as
outputs to drive push-pull loads. The PWM output signal
is output on the P1A pin, while the complementary PWM
output signal is output on the P1B pin (Figure 16-4). This
mode can be used for half-bridge applications, as shown
in Figure 16-5, or for full-bridge applications where four
power switches are being modulated with two PWM
signals.
Period
Period
Duty Cycle
(2)
(2)
P1A
td
td
P1B
In Half-Bridge Output mode, the programmable dead-
band delay can be used to prevent shoot-through
current in half-bridge power devices. The value of bits,
PDC6:PDC0, sets the number of instruction cycles
before the output is driven active. If the value is greater
than the duty cycle, the corresponding output remains
inactive during the entire cycle. See Section 16.4.6
“Programmable Dead-Band Delay” for more details
of the dead-band delay operations.
(1)
(1)
(1)
td = Dead-Band Delay
Note 1: At this time, the TMR2 register is equal to the
PR2 register.
2: Output signals are shown as active-high.
Since the P1A and P1B outputs are multiplexed with
the PORTC<2> and PORTD<5> data latches, the
TRISC<2> and TRISD<5> bits must be cleared to
configure P1A and P1B as outputs.
FIGURE 16-5:
EXAMPLES OF HALF-BRIDGE OUTPUT MODE APPLICATIONS
V+
Standard Half-Bridge Circuit (“Push-Pull”)
PIC18F4X2X
P1A
FET
Driver
+
V
-
Load
FET
Driver
+
V
-
P1B
V-
Half-Bridge Output Driving a Full-Bridge Circuit
V+
PIC18F4X2X
FET
FET
Driver
Driver
P1A
Load
FET
FET
Driver
Driver
P1B
V-
DS39631A-page 152
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
P1A, P1B, P1C and P1D outputs are multiplexed with
the PORTC<2> and PORTD<7:5> data latches. The
TRISC<2> and TRISD<7:5> bits must be cleared to
make the P1A, P1B, P1C and P1D pins outputs.
16.4.5
FULL-BRIDGE MODE
In Full-Bridge Output mode, four pins are used as
outputs; however, only two outputs are active at a time.
In the Forward mode, pin P1A is continuously active
and pin P1D is modulated. In the Reverse mode, pin
P1C is continuously active and pin P1B is modulated.
These are illustrated in Figure 16-6.
FIGURE 16-6:
FULL-BRIDGE PWM OUTPUT
Forward Mode
Period
(2)
P1A
Duty Cycle
(2)
(2)
P1B
P1C
(2)
P1D
(1)
(1)
Reverse Mode
Period
Duty Cycle
(2)
P1A
(2)
P1B
(2)
P1C
(2)
P1D
(1)
(1)
Note 1: At this time, the TMR2 register is equal to the PR2 register.
Note 2: Output signal is shown as active-high.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 153
PIC18F2420/2520/4420/4520
FIGURE 16-7:
EXAMPLE OF FULL-BRIDGE APPLICATION
V+
PIC18F4X2X
QC
QA
FET
Driver
FET
Driver
P1A
Load
P1B
FET
Driver
FET
Driver
P1C
P1D
QD
QB
V-
Figure 16-9 shows an example where the PWM
direction changes from forward to reverse at a near
100% duty cycle. At time t1, the outputs P1A and P1D
become inactive, while output P1C becomes active. In
this example, since the turn-off time of the power
devices is longer than the turn-on time, a shoot-through
current may flow through power devices, QC and QD
(see Figure 16-7), for the duration of ‘t’. The same
phenomenon will occur to power devices, QA and QB,
for PWM direction change from reverse to forward.
16.4.5.1
Direction Change in Full-Bridge Mode
In the Full-Bridge Output mode, the P1M1 bit in the
CCP1CON register allows user to control the forward/
reverse direction. When the application firmware
changes this direction control bit, the module will
assume the new direction on the next PWM cycle.
Just before the end of the current PWM period, the
modulated outputs (P1B and P1D) are placed in their
inactive state, while the unmodulated outputs (P1A and
P1C) are switched to drive in the opposite direction.
This occurs in a time interval of 4 TOSC * (Timer2
Prescale Value) before the next PWM period begins.
The Timer2 prescaler will be either 1, 4 or 16, depend-
ing on the value of the T2CKPS1:T2CKPS0 bits
(T2CON<1:0>). During the interval from the switch of
the unmodulated outputs to the beginning of the next
period, the modulated outputs (P1B and P1D) remain
inactive. This relationship is shown in Figure 16-8.
If changing PWM direction at high duty cycle is required
for an application, one of the following requirements
must be met:
1. Reduce PWM for
changing directions.
a PWM period before
2. Use switch drivers that can drive the switches off
faster than they can drive them on.
Other options to prevent shoot-through current may
exist.
Note that in the Full-Bridge Output mode, the CCP1
module does not provide any dead-band delay. In gen-
eral, since only one output is modulated at all times,
dead-band delay is not required. However, there is a
situation where a dead-band delay might be required.
This situation occurs when both of the following
conditions are true:
1. The direction of the PWM output changes when
the duty cycle of the output is at or near 100%.
2. The turn-off time of the power switch, including
the power device and driver circuit, is greater
than the turn-on time.
DS39631A-page 154
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 16-8:
PWM DIRECTION CHANGE
(1)
Period
Period
SIGNAL
P1A (Active-High)
P1B (Active-High)
DC
P1C (Active-High)
P1D (Active-High)
(Note 2)
DC
Note 1: The direction bit in the CCP1 Control register (CCP1CON<7>) is written any time during the PWM cycle.
2: When changing directions, the P1A and P1C signals switch before the end of the current PWM cycle at intervals
of 4 TOSC, 16 TOSC or 64 TOSC, depending on the Timer2 prescaler value. The modulated P1B and P1D signals
are inactive at this time.
FIGURE 16-9:
PWM DIRECTION CHANGE AT NEAR 100% DUTY CYCLE
Forward Period
Reverse Period
t1
(1)
(1)
P1A
P1B
DC
(1)
(1)
P1C
P1D
DC
(2)
t
ON
(1)
(1)
External Switch C
External Switch D
(3)
t
OFF
(2,3)
Potential
t = t
– t
ON
OFF
Shoot-Through
(1)
Current
Note 1: All signals are shown as active-high.
2: t is the turn-on delay of power switch QC and its driver.
ON
3: t
is the turn-off delay of power switch QD and its driver.
OFF
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 155
PIC18F2420/2520/4420/4520
A shutdown event can be caused by either of the
comparator modules, a low level on the Fault input pin
(FLT0) or any combination of these three sources. The
comparators may be used to monitor a voltage input
proportional to a current being monitored in the bridge
16.4.6
PROGRAMMABLE DEAD-BAND
DELAY
Note:
Programmable dead-band delay is not
implemented in 28-pin devices with
standard CCP modules.
circuit. If the voltage exceeds
a threshold, the
comparator switches state and triggers a shutdown.
Alternatively, a low digital signal on FLT0 can also trigger
a shutdown. The auto-shutdown feature can be disabled
by not selecting any auto-shutdown sources. The auto-
shutdown sources to be used are selected using the
ECCPAS2:ECCPAS0 bits (bits<6:4> of the ECCP1AS
register).
In half-bridge applications where all power switches are
modulated at the PWM frequency at all times, the
power switches normally require more time to turn off
than to turn on. If both the upper and lower power
switches are switched at the same time (one turned on
and the other turned off), both switches may be on for
a short period of time until one switch completely turns
off. During this brief interval, a very high current (shoot-
through current) may flow through both power
switches, shorting the bridge supply. To avoid this
potentially destructive shoot-through current from flow-
ing during switching, turning on either of the power
switches is normally delayed to allow the other switch
to completely turn off.
When a shutdown occurs, the output pins are asyn-
chronously placed in their shutdown states, specified
by the PSSAC1:PSSAC0 and PSSBD1:PSSBD0 bits
(ECCPAS2:ECCPAS0). Each pin pair (P1A/P1C and
P1B/P1D) may be set to drive high, drive low or be tri-
stated (not driving). The ECCPASE bit (ECCP1AS<7>)
is also set to hold the enhanced PWM outputs in their
shutdown states.
In the Half-Bridge Output mode, a digitally programma-
ble dead-band delay is available to avoid shoot-through
current from destroying the bridge power switches. The
delay occurs at the signal transition from the nonactive
state to the active state. See Figure 16-4 for illustration.
Bits PDC6:PDC0 of the PWM1CON register
(Register 16-2) set the delay period in terms of micro-
controller instruction cycles (TCY or 4 TOSC). These bits
are not available on 28-pin devices as the standard
CCP module does not support half-bridge operation.
The ECCPASE bit is set by hardware when a shutdown
event occurs. If automatic restarts are not enabled, the
ECCPASE bit is cleared by firmware when the cause of
the shutdown clears. If automatic restarts are enabled,
the ECCPASE bit is automatically cleared when the
cause of the auto-shutdown has cleared.
If the ECCPASE bit is set when a PWM period begins,
the PWM outputs remain in their shutdown state for that
entire PWM period. When the ECCPASE bit is cleared,
the PWM outputs will return to normal operation at the
beginning of the next PWM period.
16.4.7
ENHANCED PWM AUTO-SHUTDOWN
When the CCP1 is programmed for any of the enhanced
PWM modes, the active output pins may be configured
for auto-shutdown. Auto-shutdown immediately places
the enhanced PWM output pins into a defined shutdown
state when a shutdown event occurs.
Note:
Writing to the ECCPASE bit is disabled
while a shutdown condition is active.
REGISTER 16-2: PWM1CON: PWM CONFIGURATION REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
PRSEN
PDC6(1)
PDC5(1)
PDC4(1)
PDC3(1)
PDC2(1)
PDC1(1)
PDC0(1)
bit 7
bit 0
bit 7
PRSEN: PWM Restart Enable bit
1= Upon auto-shutdown, the ECCPASE bit clears automatically once the shutdown event
goes away; the PWM restarts automatically
0= Upon auto-shutdown, ECCPASE must be cleared in software to restart the PWM
bit 6-0
PDC6:PDC0: PWM Delay Count bits(1)
Delay time, in number of FOSC/4 (4 * TOSC) cycles, between the scheduled and actual time for
a PWM signal to transition to active.
Note 1: Reserved on 28-pin devices; maintain these bits clear.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS39631A-page 156
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 16-3: ECCP1AS: ENHANCED CAPTURE/COMPARE/PWM AUTO-SHUTDOWN
CONTROL REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
ECCPASE ECCPAS2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PSSBD1(1) PSSBD0(1)
bit 7
bit 0
bit 7
ECCPASE: ECCP Auto-Shutdown Event Status bit
1= A shutdown event has occurred; ECCP outputs are in shutdown state
0= ECCP outputs are operating
bit 6-4
ECCPAS2:ECCPAS0: ECCP Auto-Shutdown Source Select bits
111= FLT0 or Comparator 1 or Comparator 2
110= FLT0 or Comparator 2
101= FLT0 or Comparator 1
100= FLT0
011= Either Comparator 1 or 2
010= Comparator 2 output
001= Comparator 1 output
000= Auto-shutdown is disabled
bit 3-2
bit 1-0
PSSAC1:PSSAC0: Pins A and C Shutdown State Control bits
1x= Pins A and C are tri-state (40/44-pin devices);
PWM output is tri-state (28-pin devices)
01= Drive Pins A and C to ‘1’
00= Drive Pins A and C to ‘0’
PSSBD1:PSSBD0: Pins B and D Shutdown State Control bits(1)
1x= Pins B and D tri-state
01= Drive Pins B and D to ‘1’
00= Drive Pins B and D to ‘0’
Note 1: Reserved on 28-pin devices; maintain these bits clear.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 157
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16.4.7.1
Auto-Shutdown and Automatic
Restart
16.4.8
START-UP CONSIDERATIONS
When the ECCP module is used in the PWM mode, the
application hardware must use the proper external pull-
up and/or pull-down resistors on the PWM output pins.
When the microcontroller is released from Reset, all of
the I/O pins are in the high-impedance state. The exter-
nal circuits must keep the power switch devices in the
off state until the microcontroller drives the I/O pins with
the proper signal levels, or activates the PWM
output(s).
The auto-shutdown feature can be configured to allow
automatic restarts of the module following a shutdown
event. This is enabled by setting the PRSEN bit of the
PWM1CON register (PWM1CON<7>).
In Shutdown mode with PRSEN = 1(Figure 16-10), the
ECCPASE bit will remain set for as long as the cause
of the shutdown continues. When the shutdown condi-
tion clears, the ECCP1ASE bit is cleared. If PRSEN = 0
(Figure 16-11), once a shutdown condition occurs, the
ECCPASE bit will remain set until it is cleared by firm-
ware. Once ECCPASE is cleared, the enhanced PWM
will resume at the beginning of the next PWM period.
The CCP1M1:CCP1M0 bits (CCP1CON<1:0>) allow
the user to choose whether the PWM output signals are
active-high or active-low for each pair of PWM output
pins (P1A/P1C and P1B/P1D). The PWM output
polarities must be selected before the PWM pins are
configured as outputs. Changing the polarity configura-
tion while the PWM pins are configured as outputs is
not recommended, since it may result in damage to the
application circuits.
Note:
Writing to the ECCPASE bit is disabled
while a shutdown condition is active.
Independent of the PRSEN bit setting, if the auto-
shutdown source is one of the comparators, the
shutdown condition is a level. The ECCPASE bit
cannot be cleared as long as the cause of the shutdown
persists.
The P1A, P1B, P1C and P1D output latches may not be
in the proper states when the PWM module is initialized.
Enabling the PWM pins for output at the same time as
the ECCP module may cause damage to the applica-
tion circuit. The ECCP module must be enabled in the
proper output mode and complete a full PWM cycle
before configuring the PWM pins as outputs. The com-
pletion of a full PWM cycle is indicated by the TMR2IF
bit being set as the second PWM period begins.
The Auto-Shutdown mode can be forced by writing a ‘1’
to the ECCPASE bit.
FIGURE 16-10:
PWM AUTO-SHUTDOWN (PRSEN = 1, AUTO-RESTART ENABLED)
PWM Period
Shutdown Event
ECCPASE bit
PWM Activity
Normal PWM
Start of
PWM Period
Shutdown
Event Occurs Event Clears
Shutdown
PWM
Resumes
FIGURE 16-11:
PWM AUTO-SHUTDOWN (PRSEN = 0, AUTO-RESTART DISABLED)
PWM Period
Shutdown Event
ECCPASE bit
PWM Activity
Normal PWM
ECCPASE
Cleared by
Firmware
Start of
PWM Period
Shutdown
Shutdown
PWM
Resumes
Event Occurs Event Clears
DS39631A-page 158
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
16.4.9
SETUP FOR PWM OPERATION
16.4.10 OPERATION IN POWER MANAGED
MODES
The following steps should be taken when configuring
the ECCP module for PWM operation:
In Sleep mode, all clock sources are disabled. Timer2
will not increment and the state of the module will not
change. If the ECCP pin is driving a value, it will con-
tinue to drive that value. When the device wakes up, it
will continue from this state. If Two-Speed Start-ups are
enabled, the initial start-up frequency from INTOSC
and the postscaler may not be stable immediately.
1. Configure the PWM pins, P1A and P1B (and
P1C and P1D, if used), as inputs by setting the
corresponding TRIS bits.
2. Set the PWM period by loading the PR2 register.
3. If auto-shutdown is required:
• Disable auto-shutdown (ECCP1AS = 0)
In PRI_IDLE mode, the primary clock will continue to
clock the ECCP module without change. In all other
power managed modes, the selected power managed
mode clock will clock Timer2. Other power managed
mode clocks will most likely be different than the
primary clock frequency.
• Configure source (FLT0, Comparator 1 or
Comparator 2)
• Wait for non-shutdown condition
4. Configure the ECCP module for the desired
PWM mode and configuration by loading the
CCP1CON register with the appropriate values:
16.4.10.1 Operation with Fail-Safe
Clock Monitor
• Select one of the available output
configurations and direction with the
P1M1:P1M0 bits.
If the Fail-Safe Clock Monitor is enabled, a clock failure
will force the device into the RC_RUN Power Managed
mode and the OSCFIF bit (PIR2<7>) will be set. The
ECCP will then be clocked from the internal oscillator
clock source, which may have a different clock
frequency than the primary clock.
• Select the polarities of the PWM output
signals with the CCP1M3:CCP1M0 bits.
5. Set the PWM duty cycle by loading the CCPR1L
register and CCP1CON<5:4> bits.
6. For Half-Bridge Output mode, set the dead-
band delay by loading PWM1CON<6:0> with
the appropriate value.
See the previous section for additional details.
16.4.11 EFFECTS OF A RESET
7. If auto-shutdown operation is required, load the
ECCP1AS register:
Both Power-on Reset and subsequent Resets will force
all ports to Input mode and the CCP registers to their
Reset states.
• Select the auto-shutdown sources using the
ECCPAS2:ECCPAS0 bits.
• Select the shutdown states of the PWM
output pins using the PSSAC1:PSSAC0 and
PSSBD1:PSSBD0 bits.
This forces the enhanced CCP module to reset to a
state compatible with the standard CCP module.
• Set the ECCPASE bit (ECCP1AS<7>).
• Configure the comparators using the CMCON
register.
• Configure the comparator inputs as analog
inputs.
8. If auto-restart operation is required, set the
PRSEN bit (PWM1CON<7>).
9. Configure and start TMR2:
• Clear the TMR2 interrupt flag bit by clearing
the TMR2IF bit (PIR1<1>).
• Set the TMR2 prescale value by loading the
T2CKPS bits (T2CON<1:0>).
• Enable Timer2 by setting the TMR2ON bit
(T2CON<2>).
10. Enable PWM outputs after a new PWM cycle
has started:
• Wait until TMRn overflows (TMRnIF bit is set).
• Enable the CCP1/P1A, P1B, P1C and/or P1D
pin outputs by clearing the respective TRIS
bits.
• Clear the ECCPASE bit (ECCP1AS<7>).
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 159
PIC18F2420/2520/4420/4520
TABLE 16-3: REGISTERS ASSOCIATED WITH ECCP1 MODULE AND TIMER1 TO TIMER3
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
RCON
PIR1
GIE/GIEH PEIE/GIEL
TMR0IE
—
INT0IE
RI
RBIE
TO
TMR0IF
PD
INT0IF
POR
RBIF
49
48
52
52
52
52
52
52
52
52
52
50
50
50
50
50
50
51
51
51
51
51
51
51
51
IPEN
PSPIF
SBOREN
ADIF
BOR
RCIF
RCIE
RCIP
—
TXIF
TXIE
TXIP
EEIF
EEIE
EEIP
SSPIF
SSPIE
SSPIP
BCLIF
BCLIE
BCLIP
CCP1IF
CCP1IE
CCP1IP
HLVDIF
HLVDIE
HLVDIP
TMR2IF
TMR2IE
TMR2IP
TMR3IF
TMR3IE
TMR3IP
TMR1IF
TMR1IE
TMR1IP
CCP2IF
CCP2IE
CCP2IP
PIE1
PSPIE
ADIE
IPR1
PSPIP
ADIP
PIR2
OSCFIF
OSCFIE
OSCFIP
CMIF
CMIE
CMIP
PIE2
—
IPR2
—
TRISB
TRISC
TRISD
TMR1L
TMR1H
T1CON
TMR2
PORTB Data Direction Control Register
PORTC Data Direction Control Register
PORTD Data Direction Control Register
Timer1 Register, Low Byte
Timer1 Register, High Byte
RD16
Timer2 Register
T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0
T1RUN
T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON
T2CON
PR2
—
Timer2 Period Register
TMR3L
TMR3H
T3CON
CCPR1L
CCPR1H
CCP1CON
Timer3 Register, Low Byte
Timer3 Register, High Byte
RD16
T3CCP2
T3CKPS1 T3CKPS0
T3CCP1
T3SYNC TMR3CS TMR3ON
CCP1M2 CCP1M1 CCP1M0
Capture/Compare/PWM Register 1, Low Byte
Capture/Compare/PWM Register 1, High Byte
(1)
(1)
P1M1
P1M0
DC1B1
DC1B0
CCP1M3
PSSAC1
(1)
(1)
ECCP1AS ECCPASE ECCPAS2 ECCPAS1 ECCPAS0
PSSAC0 PSSBD1
PSSBD0
(1)
(1)
(1)
(1)
(1)
(1)
(1)
PWM1CON
PRSEN
PDC6
PDC5
PDC4
PDC3
PDC2
PDC1
PDC0
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during ECCP operation.
Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear.
DS39631A-page 160
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
17.3 SPI Mode
17.0 MASTER SYNCHRONOUS
SERIAL PORT (MSSP)
MODULE
The SPI mode allows 8 bits of data to be synchronously
transmitted and received simultaneously. All four
modes of SPI are supported. To accomplish
communication, typically three pins are used:
17.1 Master SSP (MSSP) Module
Overview
• Serial Data Out (SDO) – RC5/SDO
• Serial Data In (SDI) – RC4/SDI/SDA
The Master Synchronous Serial Port (MSSP) module is
a serial interface, useful for communicating with other
peripheral or microcontroller devices. These peripheral
devices may be serial EEPROMs, shift registers, dis-
play drivers, A/D converters, etc. The MSSP module
can operate in one of two modes:
• Serial Clock (SCK) – RC3/SCK/SCL
Additionally, a fourth pin may be used when in a Slave
mode of operation:
• Slave Select (SS) – RA5/SS
Figure 17-1 shows the block diagram of the MSSP
module when operating in SPI mode.
• Serial Peripheral Interface (SPI)
• Inter-Integrated Circuit (I2C)
- Full Master mode
FIGURE 17-1:
MSSP BLOCK DIAGRAM
(SPI MODE)
- Slave mode (with general address call)
The I2C interface supports the following modes in
hardware:
Internal
Data Bus
Read
Write
• Master mode
• Multi-Master mode
• Slave mode
SSPBUF reg
SSPSR reg
17.2 Control Registers
RC4/SDI/SDA
RC5/SDO
The MSSP module has three associated registers.
These include a status register (SSPSTAT) and two
control registers (SSPCON1 and SSPCON2). The use
of these registers and their individual configuration bits
differ significantly depending on whether the MSSP
module is operated in SPI or I2C mode.
Shift
Clock
bit 0
RA5/AN4/SS/
HLVDIN/C2OUT
Control
Enable
SS
Additional details are provided under the individual
sections.
Edge
Select
2
Clock Select
SSPM3:SSPM0
SMP:CKE
2
4
TMR2 Output
RC3/SCK/
SCL
(
)
2
Edge
Select
TOSC
Prescaler
4, 16, 64
Data to TX/RX in SSPSR
TRIS bit
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 161
PIC18F2420/2520/4420/4520
SSPSR is the shift register used for shifting data in or
out. SSPBUF is the buffer register to which data bytes
are written to or read from.
17.3.1
REGISTERS
The MSSP module has four registers for SPI mode
operation. These are:
In receive operations, SSPSR and SSPBUF together
create a double-buffered receiver. When SSPSR
receives a complete byte, it is transferred to SSPBUF
and the SSPIF interrupt is set.
• MSSP Control Register 1 (SSPCON1)
• MSSP Status Register (SSPSTAT)
• Serial Receive/Transmit Buffer Register
(SSPBUF)
During transmission, the SSPBUF is not double-
buffered. A write to SSPBUF will write to both SSPBUF
and SSPSR.
• MSSP Shift Register (SSPSR) – Not directly
accessible
SSPCON1 and SSPSTAT are the control and status
registers in SPI mode operation. The SSPCON1 regis-
ter is readable and writable. The lower 6 bits of the
SSPSTAT are read-only. The upper two bits of the
SSPSTAT are read/write.
REGISTER 17-1: SSPSTAT: MSSP STATUS REGISTER (SPI MODE)
R/W-0
SMP
R/W-0
CKE
R-0
D/A
R-0
P
R-0
S
R-0
R-0
UA
R-0
BF
R/W
bit 7
bit 0
bit 7
bit 6
SMP: Sample bit
SPI Master mode:
1= Input data sampled at end of data output time
0= Input data sampled at middle of data output time
SPI Slave mode:
SMP must be cleared when SPI is used in Slave mode.
CKE: SPI Clock Select bit
1= Transmit occurs on transition from active to Idle clock state
0= Transmit occurs on transition from Idle to active clock state
Note:
Polarity of clock state is set by the CKP bit (SSPCON1<4>).
bit 5
bit 4
D/A: Data/Address bit
Used in I2C mode only.
P: Stop bit
Used in I2C mode only. This bit is cleared when the MSSP module is disabled, SSPEN is
cleared.
bit 3
bit 2
bit 1
bit 0
S: Start bit
Used in I2C mode only.
R/W: Read/Write Information bit
Used in I2C mode only.
UA: Update Address bit
Used in I2C mode only.
BF: Buffer Full Status bit (Receive mode only)
1= Receive complete, SSPBUF is full
0= Receive not complete, SSPBUF is empty
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS39631A-page 162
Preliminary
2004 Microchip Technology Inc.
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REGISTER 17-2: SSPCON1: MSSP CONTROL REGISTER 1 (SPI MODE)
R/W-0
WCOL
R/W-0
R/W-0
R/W-0
CKP
R/W-0
R/W-0
R/W-0
R/W-0
SSPOV
SSPEN
SSPM3
SSPM2
SSPM1
SSPM0
bit 7
bit 0
bit 7
bit 6
WCOL: Write Collision Detect bit (Transmit mode only)
1= The SSPBUF register is written while it is still transmitting the previous word
(must be cleared in software)
0= No collision
SSPOV: Receive Overflow Indicator bit
SPI Slave mode:
1= A new byte is received while the SSPBUF register is still holding the previous data. In case
of overflow, the data in SSPSR is lost. Overflow can only occur in Slave mode. The user
must read the SSPBUF, even if only transmitting data, to avoid setting overflow (must be
cleared in software).
0= No overflow
Note:
In Master mode, the overflow bit is not set since each new reception (and
transmission) is initiated by writing to the SSPBUF register.
bit 5
bit 4
SSPEN: Synchronous Serial Port Enable bit
1= Enables serial port and configures SCK, SDO, SDI and SS as serial port pins
0= Disables serial port and configures these pins as I/O port pins
Note:
When enabled, these pins must be properly configured as input or output.
CKP: Clock Polarity Select bit
1= Idle state for clock is a high level
0= Idle state for clock is a low level
bit 3-0 SSPM3:SSPM0: Synchronous Serial Port Mode Select bits
0101= SPI Slave mode, clock = SCK pin, SS pin control disabled, SS can be used as I/O pin
0100= SPI Slave mode, clock = SCK pin, SS pin control enabled
0011= SPI Master mode, clock = TMR2 output/2
0010= SPI Master mode, clock = FOSC/64
0001= SPI Master mode, clock = FOSC/16
0000= SPI Master mode, clock = FOSC/4
Note:
Bit combinations not specifically listed here are either reserved or implemented in
I2C mode only.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
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reading the data that was just received. Any write to the
SSPBUF register during transmission/reception of data
will be ignored and the write collision detect bit, WCOL
(SSPCON1<7>), will be set. User software must clear
the WCOL bit so that it can be determined if the follow-
ing write(s) to the SSPBUF register completed
successfully.
17.3.2
OPERATION
When initializing the SPI, several options need to be
specified. This is done by programming the appropriate
control bits (SSPCON1<5:0> and SSPSTAT<7:6>).
These control bits allow the following to be specified:
• Master mode (SCK is the clock output)
• Slave mode (SCK is the clock input)
• Clock Polarity (Idle state of SCK)
When the application software is expecting to receive
valid data, the SSPBUF should be read before the next
byte of data to transfer is written to the SSPBUF. The
Buffer Full bit, BF (SSPSTAT<0>), indicates when
SSPBUF has been loaded with the received data
(transmission is complete). When the SSPBUF is read,
the BF bit is cleared. This data may be irrelevant if the
SPI is only a transmitter. Generally, the MSSP interrupt
is used to determine when the transmission/reception
has completed. The SSPBUF must be read and/or
written. If the interrupt method is not going to be used,
then software polling can be done to ensure that a write
collision does not occur. Example 17-1 shows the
loading of the SSPBUF (SSPSR) for data transmission.
• Data Input Sample Phase (middle or end of data
output time)
• Clock Edge (output data on rising/falling edge of
SCK)
• Clock Rate (Master mode only)
• Slave Select mode (Slave mode only)
The MSSP consists of a transmit/receive shift register
(SSPSR) and a buffer register (SSPBUF). The SSPSR
shifts the data in and out of the device, MSb first. The
SSPBUF holds the data that was written to the SSPSR
until the received data is ready. Once the 8 bits of data
have been received, that byte is moved to the SSPBUF
register. Then, the Buffer Full detect bit, BF
(SSPSTAT<0>) and the interrupt flag bit, SSPIF, are
set. This double-buffering of the received data
(SSPBUF) allows the next byte to start reception before
The SSPSR is not directly readable or writable and can
only be accessed by addressing the SSPBUF register.
Additionally, the MSSP status register (SSPSTAT)
indicates the various status conditions.
EXAMPLE 17-1:
LOADING THE SSPBUF (SSPSR) REGISTER
LOOP
BTFSS
BRA
SSPSTAT, BF
LOOP
;Has data been received (transmit complete)?
;No
MOVF
SSPBUF, W
;WREG reg = contents of SSPBUF
MOVWF
RXDATA
;Save in user RAM, if data is meaningful
MOVF
MOVWF
TXDATA, W
SSPBUF
;W reg = contents of TXDATA
;New data to xmit
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17.3.3
ENABLING SPI I/O
17.3.4
TYPICAL CONNECTION
To enable the serial port, SSP Enable bit, SSPEN
(SSPCON1<5>), must be set. To reset or reconfigure
SPI mode, clear the SSPEN bit, reinitialize the
SSPCON registers and then set the SSPEN bit. This
configures the SDI, SDO, SCK and SS pins as serial
port pins. For the pins to behave as the serial port func-
tion, some must have their data direction bits (in the
TRIS register) appropriately programmed as follows:
Figure 17-2 shows a typical connection between two
microcontrollers. The master controller (Processor 1)
initiates the data transfer by sending the SCK signal.
Data is shifted out of both shift registers on their pro-
grammed clock edge and latched on the opposite edge
of the clock. Both processors should be programmed to
the same Clock Polarity (CKP), then both controllers
would send and receive data at the same time.
Whether the data is meaningful (or dummy data)
depends on the application software. This leads to
three scenarios for data transmission:
• SDI is automatically controlled by the SPI module
• SDO must have TRISC<5> bit cleared
• SCK (Master mode) must have TRISC<3> bit
cleared
• Master sends data – Slave sends dummy data
• Master sends data – Slave sends data
• SCK (Slave mode) must have TRISC<3> bit set
• SS must have TRISA<5> bit set
• Master sends dummy data – Slave sends data
Any serial port function that is not desired may be
overridden by programming the corresponding data
direction (TRIS) register to the opposite value.
FIGURE 17-2:
SPI MASTER/SLAVE CONNECTION
SPI Master SSPM3:SSPM0 = 00xxb
SPI Slave SSPM3:SSPM0 = 010xb
SDO
SDI
Serial Input Buffer
(SSPBUF)
Serial Input Buffer
(SSPBUF)
SDI
SDO
Shift Register
(SSPSR)
Shift Register
(SSPSR)
LSb
MSb
MSb
LSb
Serial Clock
SCK
SCK
PROCESSOR 1
PROCESSOR 2
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The clock polarity is selected by appropriately
programming the CKP bit (SSPCON1<4>). This then,
would give waveforms for SPI communication as
shown in Figure 17-3, Figure 17-5 and Figure 17-6,
where the MSB is transmitted first. In Master mode, the
SPI clock rate (bit rate) is user programmable to be one
of the following:
17.3.5
MASTER MODE
The master can initiate the data transfer at any time
because it controls the SCK. The master determines
when the slave (Processor 2, Figure 17-2) is to
broadcast data by the software protocol.
In Master mode, the data is transmitted/received as
soon as the SSPBUF register is written to. If the SPI is
only going to receive, the SDO output could be dis-
abled (programmed as an input). The SSPSR register
will continue to shift in the signal present on the SDI pin
at the programmed clock rate. As each byte is
received, it will be loaded into the SSPBUF register as
if a normal received byte (interrupts and status bits
appropriately set). This could be useful in receiver
applications as a “Line Activity Monitor” mode.
• FOSC/4 (or TCY)
• FOSC/16 (or 4 • TCY)
• FOSC/64 (or 16 • TCY)
• Timer2 output/2
This allows a maximum data rate (at 40 MHz) of
10.00 Mbps.
Figure 17-3 shows the waveforms for Master mode.
When the CKE bit is set, the SDO data is valid before
there is a clock edge on SCK. The change of the input
sample is shown based on the state of the SMP bit. The
time when the SSPBUF is loaded with the received
data is shown.
FIGURE 17-3:
SPI MODE WAVEFORM (MASTER MODE)
Write to
SSPBUF
SCK
(CKP = 0
CKE = 0)
SCK
(CKP = 1
CKE = 0)
4 Clock
Modes
SCK
(CKP = 0
CKE = 1)
SCK
(CKP = 1
CKE = 1)
bit 6
bit 6
bit 2
bit 2
bit 5
bit 5
bit 4
bit 4
bit 1
bit 1
bit 0
bit 0
SDO
(CKE = 0)
bit 7
bit 7
bit 3
bit 3
SDO
(CKE = 1)
SDI
(SMP = 0)
bit 0
bit 7
Input
Sample
(SMP = 0)
SDI
(SMP = 1)
bit 0
bit 7
Input
Sample
(SMP = 1)
SSPIF
Next Q4 Cycle
after Q2↓
SSPSR to
SSPBUF
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must be high. When the SS pin is low, transmission and
reception are enabled and the SDO pin is driven. When
the SS pin goes high, the SDO pin is no longer driven,
even if in the middle of a transmitted byte and becomes
a floating output. External pull-up/pull-down resistors
may be desirable depending on the application.
17.3.6
SLAVE MODE
In Slave mode, the data is transmitted and received as
the external clock pulses appear on SCK. When the
last bit is latched, the SSPIF interrupt flag bit is set.
Before enabling the module in SPI Slave mode, the
clock line must match the proper Idle state. The clock
line can be observed by reading the SCK pin. The Idle
state is determined by the CKP bit (SSPCON1<4>).
Note 1: When the SPI is in Slave mode with SS pin
control enabled (SSPCON<3:0> = 0100),
the SPI module will reset if the SS pin is set
to VDD.
While in Slave mode, the external clock is supplied by
the external clock source on the SCK pin. This external
clock must meet the minimum high and low times as
specified in the electrical specifications.
2: If the SPI is used in Slave mode with CKE
set, then the SS pin control must be
enabled.
While in Sleep mode, the slave can transmit/receive
data. When a byte is received, the device will wake-up
from Sleep.
When the SPI module resets, the bit counter is forced
to ‘0’. This can be done by either forcing the SS pin to
a high level or clearing the SSPEN bit.
17.3.7
SLAVE SELECT
SYNCHRONIZATION
To emulate two-wire communication, the SDO pin can
be connected to the SDI pin. When the SPI needs to
operate as a receiver, the SDO pin can be configured
as an input. This disables transmissions from the SDO.
The SDI can always be left as an input (SDI function)
since it cannot create a bus conflict.
The SS pin allows a Synchronous Slave mode. The
SPI must be in Slave mode with SS pin control enabled
(SSPCON1<3:0> = 04h). The pin must not be driven
low for the SS pin to function as an input. The data latch
FIGURE 17-4:
SLAVE SYNCHRONIZATION WAVEFORM
SS
SCK
(CKP = 0
CKE = 0)
SCK
(CKP = 1
CKE = 0)
Write to
SSPBUF
bit 6
bit 7
bit 7
bit 0
SDO
bit 7
SDI
(SMP = 0)
bit 0
bit 7
Input
Sample
(SMP = 0)
SSPIF
Interrupt
Flag
Next Q4 Cycle
after Q2↓
SSPSR to
SSPBUF
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FIGURE 17-5:
SPI MODE WAVEFORM (SLAVE MODE WITH CKE = 0)
SS
Optional
SCK
(CKP = 0
CKE = 0)
SCK
(CKP = 1
CKE = 0)
Write to
SSPBUF
bit 6
bit 2
bit 5
bit 4
bit 3
bit 1
bit 0
SDO
bit 7
SDI
(SMP = 0)
bit 0
bit 7
Input
Sample
(SMP = 0)
SSPIF
Interrupt
Flag
Next Q4 Cycle
after Q2↓
SSPSR to
SSPBUF
FIGURE 17-6:
SPI MODE WAVEFORM (SLAVE MODE WITH CKE = 1)
SS
Not Optional
SCK
(CKP = 0
CKE = 1)
SCK
(CKP = 1
CKE = 1)
Write to
SSPBUF
bit 6
bit 3
bit 2
bit 5
bit 4
bit 1
bit 0
SDO
bit 7
bit 7
SDI
(SMP = 0)
bit 0
Input
Sample
(SMP = 0)
SSPIF
Interrupt
Flag
Next Q4 Cycle
after Q2↓
SSPSR to
SSPBUF
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17.3.8
OPERATION IN POWER MANAGED
MODES
17.3.9
EFFECTS OF A RESET
A Reset disables the MSSP module and terminates the
current transfer.
In SPI Master mode, module clocks may be operating
at a different speed than when in full power mode; in
the case of the Sleep mode, all clocks are halted.
17.3.10 BUS MODE COMPATIBILITY
Table 17-1 shows the compatibility between the
standard SPI modes and the states of the CKP and
CKE control bits.
In most Idle modes, a clock is provided to the peripher-
als. That clock should be from the primary clock
source, the secondary clock (Timer1 oscillator at
32.768 kHz) or the INTOSC source. See Section 2.7
“Clock Sources and Oscillator Switching” for
additional information.
TABLE 17-1: SPI BUS MODES
Control Bits State
Standard SPI Mode
In most cases, the speed that the master clocks SPI
data is not important; however, this should be
evaluated for each system.
Terminology
CKP
CKE
0, 0
0, 1
1, 0
1, 1
0
0
1
1
1
0
1
0
If MSSP interrupts are enabled, they can wake the con-
troller from Sleep mode, or one of the Idle modes, when
the master completes sending data. If an exit from
Sleep or Idle mode is not desired, MSSP interrupts
should be disabled.
There is also an SMP bit which controls when the data
is sampled.
If the Sleep mode is selected, all module clocks are
halted and the transmission/reception will remain in
that state until the devices wakes. After the device
returns to Run mode, the module will resume
transmitting and receiving data.
In SPI Slave mode, the SPI Transmit/Receive Shift
register operates asynchronously to the device. This
allows the device to be placed in any power managed
mode and data to be shifted into the SPI Transmit/
Receive Shift register. When all 8 bits have been
received, the MSSP interrupt flag bit will be set and if
enabled, will wake the device.
TABLE 17-2: REGISTERS ASSOCIATED WITH SPI OPERATION
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
PIR1
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
TXIF
RBIE
SSPIF
SSPIE
SSPIP
TMR0IF
CCP1IF
CCP1IE
CCP1IP
INT0IF
RBIF
49
52
52
52
52
52
50
50
50
PSPIF(1)
PSPIE(1)
PSPIP(1)
ADIF
ADIE
ADIP
RCIF
RCIE
RCIP
TMR2IF
TMR1IF
PIE1
TXIE
TXIP
TMR2IE TMR1IE
TMR2IP TMR1IP
IPR1
TRISA
TRISA7(2) TRISA6(2) PORTA Data Direction Control Register
TRISC
SSPBUF
SSPCON1
SSPSTAT
PORTC Data Direction Control Register
SSP Receive Buffer/Transmit Register
WCOL
SMP
SSPOV
CKE
SSPEN
D/A
CKP
P
SSPM3
S
SSPM2
R/W
SSPM1
UA
SSPM0
BF
Legend: Shaded cells are not used by the MSSP in SPI mode.
Note 1: These bits are unimplemented in 28-pin devices; always maintain these bits clear.
2: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary
oscillator modes. When disabled, these bits read as ‘0’.
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2
17.4.1
REGISTERS
17.4 I C Mode
The MSSP module has six registers for I2C operation.
These are:
The MSSP module in I2C mode fully implements all
master and slave functions (including general call
support) and provides interrupts on Start and Stop bits
in hardware to determine a free bus (multi-master
function). The MSSP module implements the standard
mode specifications as well as 7-bit and 10-bit
addressing.
• MSSP Control Register 1 (SSPCON1)
• MSSP Control Register 2 (SSPCON2)
• MSSP Status Register (SSPSTAT)
• Serial Receive/Transmit Buffer Register
(SSPBUF)
Two pins are used for data transfer:
• MSSP Shift Register (SSPSR) – Not directly
accessible
• Serial clock (SCL) – RC3/SCK/SCL
• Serial data (SDA) – RC4/SDI/SDA
• MSSP Address Register (SSPADD)
The user must configure these pins as inputs or outputs
through the TRISC<4:3> bits.
SSPCON1, SSPCON2 and SSPSTAT are the control
and status registers in I2C mode operation. The
SSPCON1 and SSPCON2 registers are readable and
writable. The lower 6 bits of the SSPSTAT are read-only.
The upper two bits of the SSPSTAT are read/write.
FIGURE 17-7:
MSSP BLOCK DIAGRAM
(I2C MODE)
SSPSR is the shift register used for shifting data in or
out. SSPBUF is the buffer register to which data bytes
are written to or read from.
Internal
Data Bus
Read
Write
SSPADD register holds the slave device address when
the SSP is configured in I2C Slave mode. When the
SSP is configured in Master mode, the lower seven bits
of SSPADD act as the Baud Rate Generator reload
value.
SSPBUF reg
RC3/SCK/SCL
Shift
Clock
In receive operations, SSPSR and SSPBUF together
create a double-buffered receiver. When SSPSR
receives a complete byte, it is transferred to SSPBUF
and the SSPIF interrupt is set.
SSPSR reg
RC4/SDI/
SDA
MSb
LSb
Match Detect
Addr Match
During transmission, the SSPBUF is not double-
buffered. A write to SSPBUF will write to both SSPBUF
and SSPSR.
SSPADD reg
Start and
Set, Reset
S, P bits
(SSPSTAT reg)
Stop bit Detect
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REGISTER 17-3: SSPSTAT: MSSP STATUS REGISTER (I2C MODE)
R/W-0
SMP
R/W-0
CKE
R-0
D/A
R-0
P
R-0
S
R-0
R-0
UA
R-0
BF
R/W
bit 7
bit 0
bit 7
SMP: Slew Rate Control bit
In Master or Slave mode:
1 = Slew rate control disabled for standard speed mode (100 kHz and 1 MHz)
0 = Slew rate control enabled for high-speed mode (400 kHz)
bit 6
bit 5
CKE: SMBus Select bit
In Master or Slave mode:
1= Enable SMBus specific inputs
0= Disable SMBus specific inputs
D/A: Data/Address bit
In Master mode:
Reserved.
In Slave mode:
1= Indicates that the last byte received or transmitted was data
0= Indicates that the last byte received or transmitted was address
bit 4
bit 3
bit 2
P: Stop bit
1= Indicates that a Stop bit has been detected last
0= Stop bit was not detected last
Note:
This bit is cleared on Reset and when SSPEN is cleared.
S: Start bit
1= Indicates that a Start bit has been detected last
0= Start bit was not detected last
Note:
This bit is cleared on Reset and when SSPEN is cleared.
R/W: Read/Write Information bit (I2C mode only)
In Slave mode:
1= Read
0= Write
Note:
This bit holds the R/W bit information following the last address match. This bit is
only valid from the address match to the next Start bit, Stop bit or not ACK bit.
In Master mode:
1= Transmit is in progress
0= Transmit is not in progress
Note:
ORing this bit with SEN, RSEN, PEN, RCEN or ACKEN will indicate if the MSSP is
in Active mode.
bit 1
bit 0
UA: Update Address bit (10-bit Slave mode only)
1= Indicates that the user needs to update the address in the SSPADD register
0= Address does not need to be updated
BF: Buffer Full Status bit
In Transmit mode:
1= SSPBUF is full
0= SSPBUF is empty
In Receive mode:
1= SSPBUF is full (does not include the ACK and Stop bits)
0= SSPBUF is empty (does not include the ACK and Stop bits)
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
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REGISTER 17-4: SSPCON1: MSSP CONTROL REGISTER 1 (I2C MODE)
R/W-0
WCOL
R/W-0
R/W-0
R/W-0
CKP
R/W-0
R/W-0
R/W-0
R/W-0
SSPOV
SSPEN
SSPM3
SSPM2
SSPM1
SSPM0
bit 7
bit 0
bit 7
WCOL: Write Collision Detect bit
In Master Transmit mode:
1= A write to the SSPBUF register was attempted while the I2C conditions were not valid for a
transmission to be started (must be cleared in software)
0= No collision
In Slave Transmit mode:
1= The SSPBUF register is written while it is still transmitting the previous word (must be
cleared in software)
0= No collision
In Receive mode (Master or Slave modes):
This is a “don’t care” bit.
bit 6
SSPOV: Receive Overflow Indicator bit
In Receive mode:
1= A byte is received while the SSPBUF register is still holding the previous byte (must be
cleared in software)
0= No overflow
In Transmit mode:
This is a “don’t care” bit in Transmit mode.
bit 5
bit 4
SSPEN: Synchronous Serial Port Enable bit
1= Enables the serial port and configures the SDA and SCL pins as the serial port pins
0= Disables serial port and configures these pins as I/O port pins
Note:
When enabled, the SDA and SCL pins must be properly configured as input or
output.
CKP: SCK Release Control bit
In Slave mode:
1= Release clock
0= Holds clock low (clock stretch), used to ensure data setup time
In Master mode:
Unused in this mode.
bit 3-0 SSPM3:SSPM0: Synchronous Serial Port Mode Select bits
1111= I2C Slave mode, 10-bit address with Start and Stop bit interrupts enabled
1110= I2C Slave mode, 7-bit address with Start and Stop bit interrupts enabled
1011= I2C Firmware Controlled Master mode (Slave Idle)
1000= I2C Master mode, clock = FOSC/(4 * (SSPADD + 1))
0111= I2C Slave mode, 10-bit address
0110= I2C Slave mode, 7-bit address
Bit combinations not specifically listed here are either reserved or implemented in SPI mode only.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
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REGISTER 17-5: SSPCON2: MSSP CONTROL REGISTER 2 (I2C MODE)
R/W-0
GCEN
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
SEN(1)
ACKSTAT
ACKDT
ACKEN(1) RCEN(1) PEN(1) RSEN(1)
bit 7
bit 0
bit 7
bit 6
bit 5
GCEN: General Call Enable bit (Slave mode only)
1= Enable interrupt when a general call address (0000h) is received in the SSPSR
0= General call address disabled
ACKSTAT: Acknowledge Status bit (Master Transmit mode only)
1= Acknowledge was not received from slave
0= Acknowledge was received from slave
ACKDT: Acknowledge Data bit (Master Receive mode only)
1= Not Acknowledge
0= Acknowledge
Note:
Value that will be transmitted when the user initiates an Acknowledge sequence at
the end of a receive.
bit 4
ACKEN: Acknowledge Sequence Enable bit (Master Receive mode only)(1)
1= Initiate Acknowledge sequence on SDA and SCL pins and transmit ACKDT data bit.
Automatically cleared by hardware.
0= Acknowledge sequence Idle
bit 3
bit 2
RCEN: Receive Enable bit (Master mode only)(1)
1= Enables Receive mode for I2C
0= Receive Idle
PEN: Stop Condition Enable bit (Master mode only)(1)
1= Initiate Stop condition on SDA and SCL pins. Automatically cleared by hardware.
0= Stop condition Idle
bit 1
bit 0
RSEN: Repeated Start Condition Enable bit (Master mode only)(1)
1= Initiate Repeated Start condition on SDA and SCL pins. Automatically cleared by hardware.
0= Repeated Start condition Idle
SEN: Start Condition Enable/Stretch Enable bit(1)
In Master mode:
1= Initiate Start condition on SDA and SCL pins. Automatically cleared by hardware.
0= Start condition Idle
In Slave mode:
1= Clock stretching is enabled for both slave transmit and slave receive (stretch enabled)
0= Clock stretching is disabled
Note 1: For bits ACKEN, RCEN, PEN, RSEN, SEN: If the I2C module is not in the Idle mode,
these bits may not be set (no spooling) and the SSPBUF may not be written (or
writes to the SSPBUF are disabled).
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
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17.4.2
OPERATION
17.4.3.1
Addressing
The MSSP module functions are enabled by setting
MSSP Enable bit, SSPEN (SSPCON<5>).
The SSPCON1 register allows control of the I2C
operation. Four mode selection bits (SSPCON<3:0>)
allow one of the following I2C modes to be selected:
• I2C Master mode, clock = (FOSC/4) x (SSPADD + 1)
• I2C Slave mode (7-bit address)
• I2C Slave mode (10-bit address)
Once the MSSP module has been enabled, it waits for
a Start condition to occur. Following the Start condition,
the 8 bits are shifted into the SSPSR register. All
incoming bits are sampled with the rising edge of the
clock (SCL) line. The value of register SSPSR<7:1> is
compared to the value of the SSPADD register. The
address is compared on the falling edge of the eighth
clock (SCL) pulse. If the addresses match and the BF
and SSPOV bits are clear, the following events occur:
• I2C Slave mode (7-bit address) with Start and
Stop bit interrupts enabled
• I2C Slave mode (10-bit address) with Start and
Stop bit interrupts enabled
• I2C Firmware Controlled Master mode, slave is
Idle
Selection of any I2C mode with the SSPEN bit set,
forces the SCL and SDA pins to be open-drain,
provided these pins are programmed to inputs by
setting the appropriate TRISC bits. To ensure proper
operation of the module, pull-up resistors must be
provided externally to the SCL and SDA pins.
1. The SSPSR register value is loaded into the
SSPBUF register.
2. The Buffer Full bit, BF, is set.
3. An ACK pulse is generated.
4. MSSP Interrupt Flag bit, SSPIF (PIR1<3>), is
set (interrupt is generated, if enabled) on the
falling edge of the ninth SCL pulse.
In 10-bit Address mode, two address bytes need to be
received by the slave. The five Most Significant bits
(MSbs) of the first address byte specify if this is a 10-bit
address. Bit R/W (SSPSTAT<2>) must specify a write so
the slave device will receive the second address byte.
For a 10-bit address, the first byte would equal ‘11110
A9 A8 0’, where ‘A9’ and ‘A8’ are the two MSbs of the
address. The sequence of events for 10-bit address is as
follows, with steps 7 through 9 for the slave-transmitter:
17.4.3
SLAVE MODE
In Slave mode, the SCL and SDA pins must be config-
ured as inputs (TRISC<4:3> set). The MSSP module
will override the input state with the output data when
required (slave-transmitter).
The I2C Slave mode hardware will always generate an
interrupt on an address match. Through the mode
select bits, the user can also choose to interrupt on
Start and Stop bits
1. Receive first (high) byte of address (bits SSPIF,
BF and UA (SSPSTAT<1>) are set).
2. Update the SSPADD register with second (low)
byte of address (clears bit UA and releases the
SCL line).
3. Read the SSPBUF register (clears bit BF) and
clear flag bit, SSPIF.
When an address is matched, or the data transfer after
an address match is received, the hardware automati-
cally will generate the Acknowledge (ACK) pulse and
load the SSPBUF register with the received value
currently in the SSPSR register.
4. Receive second (low) byte of address (bits
SSPIF, BF and UA are set).
5. Update the SSPADD register with the first (high)
byte of address. If match releases SCL line, this
will clear bit UA.
Any combination of the following conditions will cause
the MSSP module not to give this ACK pulse:
6. Read the SSPBUF register (clears bit BF) and
clear flag bit, SSPIF.
• The Buffer Full bit, BF (SSPSTAT<0>), was set
before the transfer was received.
7. Receive Repeated Start condition.
• The overflow bit, SSPOV (SSPCON<6>), was set
before the transfer was received.
8. Receive first (high) byte of address (bits SSPIF
and BF are set).
9. Read the SSPBUF register (clears bit BF) and
clear flag bit, SSPIF.
In this case, the SSPSR register value is not loaded
into the SSPBUF, but bit SSPIF (PIR1<3>) is set. The
BF bit is cleared by reading the SSPBUF register, while
bit SSPOV is cleared through software.
The SCL clock input must have a minimum high and
low for proper operation. The high and low times of the
I2C specification, as well as the requirement of the
MSSP module, are shown in timing parameter 100 and
parameter 101.
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17.4.3.2
Reception
17.4.3.3
Transmission
When the R/W bit of the address byte is clear and an
address match occurs, the R/W bit of the SSPSTAT
register is cleared. The received address is loaded into
the SSPBUF register and the SDA line is held low
(ACK).
When the R/W bit of the incoming address byte is set
and an address match occurs, the R/W bit of the
SSPSTAT register is set. The received address is
loaded into the SSPBUF register. The ACK pulse will
be sent on the ninth bit and pin RC3/SCK/SCL is held
low regardless of SEN (see Section 17.4.4 “Clock
Stretching” for more detail). By stretching the clock,
the master will be unable to assert another clock pulse
until the slave is done preparing the transmit data. The
transmit data must be loaded into the SSPBUF register
which also loads the SSPSR register. Then pin RC3/
SCK/SCL should be enabled by setting bit, CKP
(SSPCON1<4>). The eight data bits are shifted out on
the falling edge of the SCL input. This ensures that the
SDA signal is valid during the SCL high time
(Figure 17-9).
When the address byte overflow condition exists, then
the no Acknowledge (ACK) pulse is given. An overflow
condition is defined as either bit BF (SSPSTAT<0>) is
set, or bit SSPOV (SSPCON1<6>) is set.
An MSSP interrupt is generated for each data transfer
byte. Flag bit, SSPIF (PIR1<3>), must be cleared in
software. The SSPSTAT register is used to determine
the status of the byte.
If SEN is enabled (SSPCON2<0> = 1), RC3/SCK/SCL
will be held low (clock stretch) following each data
transfer. The clock must be released by setting bit,
CKP (SSPCON<4>). See Section 17.4.4 “Clock
Stretching” for more detail.
The ACK pulse from the master-receiver is latched on
the rising edge of the ninth SCL input pulse. If the SDA
line is high (not ACK), then the data transfer is com-
plete. In this case, when the ACK is latched by the
slave, the slave logic is reset (resets SSPSTAT regis-
ter) and the slave monitors for another occurrence of
the Start bit. If the SDA line was low (ACK), the next
transmit data must be loaded into the SSPBUF register.
Again, pin RC3/SCK/SCL must be enabled by setting
bit CKP.
An MSSP interrupt is generated for each data transfer
byte. The SSPIF bit must be cleared in software and
the SSPSTAT register is used to determine the status
of the byte. The SSPIF bit is set on the falling edge of
the ninth clock pulse.
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2
FIGURE 17-8:
I C™ SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 7-BIT ADDRESS)
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2
FIGURE 17-9:
I C™ SLAVE MODE TIMING (TRANSMISSION, 7-BIT ADDRESS)
2004 Microchip Technology Inc.
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FIGURE 17-10:
I2C™ SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 10-BIT ADDRESS)
DS39631A-page 178
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2
FIGURE 17-11:
I C™ SLAVE MODE TIMING (TRANSMISSION, 10-BIT ADDRESS)
2004 Microchip Technology Inc.
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17.4.4
CLOCK STRETCHING
17.4.4.3
Clock Stretching for 7-bit Slave
Transmit Mode
Both 7-bit and 10-bit Slave modes implement
automatic clock stretching during a transmit sequence.
7-bit Slave Transmit mode implements clock stretching
by clearing the CKP bit after the falling edge of the
ninth clock if the BF bit is clear. This occurs regardless
of the state of the SEN bit.
The SEN bit (SSPCON2<0>) allows clock stretching to
be enabled during receives. Setting SEN will cause
the SCL pin to be held low at the end of each data
receive sequence.
The user’s ISR must set the CKP bit before transmis-
sion is allowed to continue. By holding the SCL line
low, the user has time to service the ISR and load the
contents of the SSPBUF before the master device can
initiate another transmit sequence (see Figure 17-9).
17.4.4.1
Clock Stretching for 7-bit Slave
Receive Mode (SEN = 1)
In 7-bit Slave Receive mode, on the falling edge of the
ninth clock at the end of the ACK sequence if the BF
bit is set, the CKP bit in the SSPCON1 register is
automatically cleared, forcing the SCL output to be
held low. The CKP being cleared to ‘0’ will assert the
SCL line low. The CKP bit must be set in the user’s
ISR before reception is allowed to continue. By holding
the SCL line low, the user has time to service the ISR
and read the contents of the SSPBUF before the
master device can initiate another receive sequence.
This will prevent buffer overruns from occurring (see
Figure 17-13).
Note 1: If the user loads the contents of SSPBUF,
setting the BF bit before the falling edge of
the ninth clock, the CKP bit will not be
cleared and clock stretching will not occur.
2: The CKP bit can be set in software
regardless of the state of the BF bit.
17.4.4.4
Clock Stretching for 10-bit Slave
Transmit Mode
In 10-bit Slave Transmit mode, clock stretching is con-
trolled during the first two address sequences by the
state of the UA bit, just as it is in 10-bit Slave Receive
mode. The first two addresses are followed by a third
address sequence which contains the high-order bits
of the 10-bit address and the R/W bit set to ‘1’. After
the third address sequence is performed, the UA bit is
not set, the module is now configured in Transmit
mode and clock stretching is controlled by the BF flag
as in 7-bit Slave Transmit mode (see Figure 17-11).
Note 1: If the user reads the contents of the
SSPBUF before the falling edge of the
ninth clock, thus clearing the BF bit, the
CKP bit will not be cleared and clock
stretching will not occur.
2: The CKP bit can be set in software
regardless of the state of the BF bit. The
user should be careful to clear the BF bit
in the ISR before the next receive
sequence in order to prevent an overflow
condition.
17.4.4.2
Clock Stretching for 10-bit Slave
Receive Mode (SEN = 1)
In 10-bit Slave Receive mode during the address
sequence, clock stretching automatically takes place
but CKP is not cleared. During this time, if the UA bit is
set after the ninth clock, clock stretching is initiated.
The UA bit is set after receiving the upper byte of the
10-bit address and following the receive of the second
byte of the 10-bit address with the R/W bit cleared to
‘0’. The release of the clock line occurs upon updating
SSPADD. Clock stretching will occur on each data
receive sequence as described in 7-bit mode.
Note:
If the user polls the UA bit and clears it by
updating the SSPADD register before the
falling edge of the ninth clock occurs and if
the user hasn’t cleared the BF bit by read-
ing the SSPBUF register before that time,
then the CKP bit will still NOT be asserted
low. Clock stretching on the basis of the
state of the BF bit only occurs during a
data sequence, not an address sequence.
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already asserted the SCL line. The SCL output will
remain low until the CKP bit is set and all other
devices on the I2C bus have deasserted SCL. This
ensures that a write to the CKP bit will not violate the
minimum high time requirement for SCL (see
Figure 17-12).
17.4.4.5
Clock Synchronization and
the CKP bit
When the CKP bit is cleared, the SCL output is forced
to ‘0’. However, clearing the CKP bit will not assert the
SCL output low until the SCL output is already sam-
pled low. Therefore, the CKP bit will not assert the
SCL line until an external I2C master device has
FIGURE 17-12:
CLOCK SYNCHRONIZATION TIMING
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
SDA
SCL
DX
DX – 1
Master device
asserts clock
CKP
Master device
deasserts clock
WR
SSPCON
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2
FIGURE 17-13:
I C™ SLAVE MODE TIMING WITH SEN = 1 (RECEPTION, 7-BIT ADDRESS)
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FIGURE 17-14:
I2C™ SLAVE MODE TIMING WITH SEN = 1 (RECEPTION, 10-BIT ADDRESS)
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 183
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If the general call address matches, the SSPSR is
transferred to the SSPBUF, the BF flag bit is set (eighth
bit) and on the falling edge of the ninth bit (ACK bit), the
SSPIF interrupt flag bit is set.
17.4.5
GENERAL CALL ADDRESS
SUPPORT
The addressing procedure for the I2C bus is such that
the first byte after the Start condition usually
determines which device will be the slave addressed by
the master. The exception is the general call address
which can address all devices. When this address is
used, all devices should, in theory, respond with an
Acknowledge.
When the interrupt is serviced, the source for the
interrupt can be checked by reading the contents of the
SSPBUF. The value can be used to determine if the
address was device specific or a general call address.
In 10-bit mode, the SSPADD is required to be updated
for the second half of the address to match and the UA
bit is set (SSPSTAT<1>). If the general call address is
sampled when the GCEN bit is set, while the slave is
configured in 10-bit Address mode, then the second
half of the address is not necessary, the UA bit will not
be set and the slave will begin receiving data after the
Acknowledge (Figure 17-15).
The general call address is one of eight addresses
reserved for specific purposes by the I2C protocol. It
consists of all ‘0’s with R/W = 0.
The general call address is recognized when the Gen-
eral Call Enable bit, GCEN, is enabled (SSPCON2<7>
is set). Following a Start bit detect, 8 bits are shifted into
the SSPSR and the address is compared against the
SSPADD. It is also compared to the general call
address and fixed in hardware.
FIGURE 17-15:
SLAVE MODE GENERAL CALL ADDRESS SEQUENCE
(7 OR 10-BIT ADDRESS MODE)
Address is compared to General Call Address
after ACK, set interrupt
Receiving Data
D5 D4 D3 D2 D1
ACK
R/W = 0
General Call Address
ACK
9
SDA
SCL
D7 D6
D0
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
9
S
SSPIF
BF (SSPSTAT<0>)
Cleared in software
SSPBUF is read
SSPOV (SSPCON1<6>)
GCEN (SSPCON2<7>)
‘0’
‘1’
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17.4.6
MASTER MODE
Note:
The MSSP module, when configured in
I2C Master mode, does not allow queueing
of events. For instance, the user is not
allowed to initiate a Start condition and
immediately write the SSPBUF register to
initiate transmission before the Start condi-
tion is complete. In this case, the SSPBUF
will not be written to and the WCOL bit will
be set, indicating that a write to the
SSPBUF did not occur.
Master mode is enabled by setting and clearing the
appropriate SSPM bits in SSPCON1 and by setting the
SSPEN bit. In Master mode, the SCL and SDA lines
are manipulated by the MSSP hardware.
Master mode of operation is supported by interrupt
generation on the detection of the Start and Stop con-
ditions. The Stop (P) and Start (S) bits are cleared from
a Reset or when the MSSP module is disabled. Control
of the I2C bus may be taken when the P bit is set, or the
bus is Idle, with both the S and P bits clear.
The following events will cause the SSP Interrupt Flag
bit, SSPIF, to be set (SSP interrupt, if enabled):
In Firmware Controlled Master mode, user code
conducts all I2C bus operations based on Start and
Stop bit conditions.
• Start condition
• Stop condition
Once Master mode is enabled, the user has six
options.
• Data transfer byte transmitted/received
• Acknowledge transmit
• Repeated Start
1. Assert a Start condition on SDA and SCL.
2. Assert a Repeated Start condition on SDA and
SCL.
3. Write to the SSPBUF register initiating
transmission of data/address.
4. Configure the I2C port to receive data.
5. Generate an Acknowledge condition at the end
of a received byte of data.
6. Generate a Stop condition on SDA and SCL.
2
FIGURE 17-16:
MSSP BLOCK DIAGRAM (I C MASTER MODE)
Internal
Data Bus
SSPM3:SSPM0
SSPADD<6:0>
Read
Write
SSPBUF
SSPSR
Baud
Rate
Generator
SDA
Shift
Clock
SDA In
MSb
LSb
Start bit, Stop bit,
Acknowledge
Generate
SCL
Start bit Detect
Stop bit Detect
Write Collision Detect
Clock Arbitration
State Counter for
end of XMIT/RCV
SCL In
Bus Collision
Set/Reset, S, P, WCOL (SSPSTAT)
Set SSPIF, BCLIF
Reset ACKSTAT, PEN (SSPCON2)
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I2C Master Mode Operation
A typical transmit sequence would go as follows:
17.4.6.1
1. The user generates a Start condition by setting
the Start Enable bit, SEN (SSPCON2<0>).
The master device generates all of the serial clock
pulses and the Start and Stop conditions. A transfer is
ended with a Stop condition or with a Repeated Start
condition. Since the Repeated Start condition is also
the beginning of the next serial transfer, the I2C bus will
not be released.
2. SSPIF is set. The MSSP module will wait the
required start time before any other operation
takes place.
3. The user loads the SSPBUF with the slave
address to transmit.
In Master Transmitter mode, serial data is output
through SDA, while SCL outputs the serial clock. The
first byte transmitted contains the slave address of the
receiving device (7 bits) and the Read/Write (R/W) bit.
In this case, the R/W bit will be logic ‘0’. Serial data is
transmitted 8 bits at a time. After each byte is transmit-
ted, an Acknowledge bit is received. Start and Stop
conditions are output to indicate the beginning and the
end of a serial transfer.
4. Address is shifted out the SDA pin until all 8 bits
are transmitted.
5. The MSSP module shifts in the ACK bit from the
slave device and writes its value into the
SSPCON2 register (SSPCON2<6>).
6. The MSSP module generates an interrupt at the
end of the ninth clock cycle by setting the SSPIF
bit.
In Master Receive mode, the first byte transmitted con-
tains the slave address of the transmitting device
(7 bits) and the R/W bit. In this case, the R/W bit will be
logic ‘1’. Thus, the first byte transmitted is a 7-bit slave
address followed by a ‘1’ to indicate the receive bit.
Serial data is received via SDA, while SCL outputs the
serial clock. Serial data is received 8 bits at a time. After
each byte is received, an Acknowledge bit is transmit-
ted. Start and Stop conditions indicate the beginning
and end of transmission.
7. The user loads the SSPBUF with eight bits of
data.
8. Data is shifted out the SDA pin until all 8 bits are
transmitted.
9. The MSSP module shifts in the ACK bit from the
slave device and writes its value into the
SSPCON2 register (SSPCON2<6>).
10. The MSSP module generates an interrupt at the
end of the ninth clock cycle by setting the SSPIF
bit.
The Baud Rate Generator used for the SPI mode
operation is used to set the SCL clock frequency for
either 100 kHz, 400 kHz or 1 MHz I2C operation. See
Section 17.4.7 “Baud Rate” for more detail.
11. The user generates a Stop condition by setting
the Stop Enable bit, PEN (SSPCON2<2>).
12. Interrupt is generated once the Stop condition is
complete.
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Once the given operation is complete (i.e., transmis-
sion of the last data bit is followed by ACK), the internal
clock will automatically stop counting and the SCL pin
will remain in its last state.
17.4.7
BAUD RATE
In I2C Master mode, the Baud Rate Generator (BRG)
reload value is placed in the lower 7 bits of the
SSPADD register (Figure 17-17). When a write occurs
to SSPBUF, the Baud Rate Generator will automatically
begin counting. The BRG counts down to ‘0’ and stops
until another reload has taken place. The BRG count is
decremented twice per instruction cycle (TCY) on the
Q2 and Q4 clocks. In I2C Master mode, the BRG is
reloaded automatically.
Table 17-3 demonstrates clock rates based on
instruction cycles and the BRG value loaded into
SSPADD.
FIGURE 17-17:
BAUD RATE GENERATOR BLOCK DIAGRAM
SSPM3:SSPM0
SSPADD<6:0>
SSPM3:SSPM0
SCL
Reload
Control
Reload
BRG Down Counter
CLKO
FOSC/4
TABLE 17-3: I2C CLOCK RATE W/BRG
FSCL
FCY
FCY*2
BRG Value
(2 Rollovers of BRG)
10 MHz
10 MHz
10 MHz
4 MHz
4 MHz
4 MHz
1 MHz
1 MHz
1 MHz
20 MHz
20 MHz
20 MHz
8 MHz
8 MHz
8 MHz
2 MHz
2 MHz
2 MHz
18h
1Fh
63h
09h
0Ch
27h
02h
09h
00h
400 kHz(1)
312.5 kHz
100 kHz
400 kHz(1)
308 kHz
100 kHz
333 kHz(1)
100 kHz
1 MHz(1)
Note 1: The I2C interface does not conform to the 400 kHz I2C specification (which applies to rates greater than
100 kHz) in all details, but may be used with care where higher rates are required by the application.
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SCL pin is sampled high, the Baud Rate Generator is
reloaded with the contents of SSPADD<6:0> and
begins counting. This ensures that the SCL high time
will always be at least one BRG rollover count in the
event that the clock is held low by an external device
(Figure 17-18).
17.4.7.1
Clock Arbitration
Clock arbitration occurs when the master, during any
receive, transmit or Repeated Start/Stop condition,
deasserts the SCL pin (SCL allowed to float high).
When the SCL pin is allowed to float high, the Baud
Rate Generator (BRG) is suspended from counting
until the SCL pin is actually sampled high. When the
FIGURE 17-18:
BAUD RATE GENERATOR TIMING WITH CLOCK ARBITRATION
SDA
DX
DX – 1
SCL allowed to transition high
SCL deasserted but slave holds
SCL low (clock arbitration)
SCL
BRG decrements on
Q2 and Q4 cycles
BRG
Value
03h
02h
01h
00h (hold off)
03h
02h
SCL is sampled high, reload takes
place and BRG starts its count
BRG
Reload
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17.4.8
I2C MASTER MODE START
CONDITION TIMING
Note:
If at the beginning of the Start condition,
the SDA and SCL pins are already sam-
pled low, or if during the Start condition, the
SCL line is sampled low before the SDA
line is driven low, a bus collision occurs,
the Bus Collision Interrupt Flag, BCLIF, is
set, the Start condition is aborted and the
I2C module is reset into its Idle state.
To initiate a Start condition, the user sets the Start
Enable bit, SEN (SSPCON2<0>). If the SDA and SCL
pins are sampled high, the Baud Rate Generator is
reloaded with the contents of SSPADD<6:0> and starts
its count. If SCL and SDA are both sampled high when
the Baud Rate Generator times out (TBRG), the SDA
pin is driven low. The action of the SDA being driven
low while SCL is high is the Start condition and causes
the S bit (SSPSTAT<3>) to be set. Following this, the
Baud Rate Generator is reloaded with the contents of
SSPADD<6:0> and resumes its count. When the Baud
Rate Generator times out (TBRG), the SEN bit
(SSPCON2<0>) will be automatically cleared by
hardware; the Baud Rate Generator is suspended,
leaving the SDA line held low and the Start condition is
complete.
17.4.8.1
WCOL Status Flag
If the user writes the SSPBUF when a Start sequence
is in progress, the WCOL is set and the contents of the
buffer are unchanged (the write doesn’t occur).
Note:
Because queueing of events is not
allowed, writing to the lower 5 bits of
SSPCON2 is disabled until the Start
condition is complete.
FIGURE 17-19:
FIRST START BIT TIMING
Set S bit (SSPSTAT<3>)
At completion of Start bit,
Write to SEN bit occurs here
SDA = 1,
SCL = 1
hardware clears SEN bit
and sets SSPIF bit
TBRG
TBRG
Write to SSPBUF occurs here
2nd bit
1st bit
SDA
TBRG
SCL
TBRG
S
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17.4.9
I2C MASTER MODE REPEATED
START CONDITION TIMING
Note 1: If RSEN is programmed while any other
event is in progress, it will not take effect.
A Repeated Start condition occurs when the RSEN bit
(SSPCON2<1>) is programmed high and the I2C logic
module is in the Idle state. When the RSEN bit is set,
the SCL pin is asserted low. When the SCL pin is sam-
pled low, the Baud Rate Generator is loaded with the
contents of SSPADD<5:0> and begins counting. The
SDA pin is released (brought high) for one Baud Rate
Generator count (TBRG). When the Baud Rate Genera-
tor times out, if SDA is sampled high, the SCL pin will
be deasserted (brought high). When SCL is sampled
high, the Baud Rate Generator is reloaded with the
contents of SSPADD<6:0> and begins counting. SDA
and SCL must be sampled high for one TBRG. This
action is then followed by assertion of the SDA pin
(SDA = 0) for one TBRG while SCL is high. Following
this, the RSEN bit (SSPCON2<1>) will be automatically
cleared and the Baud Rate Generator will not be
reloaded, leaving the SDA pin held low. As soon as a
Start condition is detected on the SDA and SCL pins,
the S bit (SSPSTAT<3>) will be set. The SSPIF bit will
not be set until the Baud Rate Generator has timed out.
2: A bus collision during the Repeated Start
condition occurs if:
• SDA is sampled low when SCL goes
from low-to-high.
• SCL goes low before SDA is
asserted low. This may indicate that
another master is attempting to
transmit a data ‘1’.
Immediately following the SSPIF bit getting set, the user
may write the SSPBUF with the 7-bit address in 7-bit
mode or the default first address in 10-bit mode. After the
first eight bits are transmitted and an ACK is received,
the user may then transmit an additional eight bits of
address (10-bit mode) or eight bits of data (7-bit mode).
17.4.9.1
WCOL Status Flag
If the user writes the SSPBUF when a Repeated Start
sequence is in progress, the WCOL is set and the
contents of the buffer are unchanged (the write doesn’t
occur).
Note:
Because queueing of events is not
allowed, writing of the lower 5 bits of
SSPCON2 is disabled until the Repeated
Start condition is complete.
FIGURE 17-20:
REPEAT START CONDITION WAVEFORM
S bit set by hardware
Write to SSPCON2
occurs here.
SDA = 1,
SCL (no change).
SDA = 1,
SCL = 1
At completion of Start bit,
hardware clears RSEN bit
and sets SSPIF
TBRG
TBRG
TBRG
1st bit
SDA
RSEN bit set by hardware
on falling edge of ninth clock,
end of Xmit
Write to SSPBUF occurs here
TBRG
SCL
TBRG
Sr = Repeated Start
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17.4.10 I2C MASTER MODE
TRANSMISSION
17.4.10.3 ACKSTAT Status Flag
In Transmit mode, the ACKSTAT bit (SSPCON2<6>) is
cleared when the slave has sent an Acknowledge
(ACK = 0) and is set when the slave does not Acknowl-
edge (ACK = 1). A slave sends an Acknowledge when
it has recognized its address (including a general call),
or when the slave has properly received its data.
Transmission of a data byte, a 7-bit address or the
other half of a 10-bit address is accomplished by simply
writing a value to the SSPBUF register. This action will
set the Buffer Full flag bit, BF and allow the Baud Rate
Generator to begin counting and start the next trans-
mission. Each bit of address/data will be shifted out
onto the SDA pin after the falling edge of SCL is
asserted (see data hold time specification
parameter 106). SCL is held low for one Baud Rate
Generator rollover count (TBRG). Data should be valid
before SCL is released high (see data setup time spec-
ification parameter 107). When the SCL pin is released
high, it is held that way for TBRG. The data on the SDA
pin must remain stable for that duration and some hold
time after the next falling edge of SCL. After the eighth
bit is shifted out (the falling edge of the eighth clock),
the BF flag is cleared and the master releases SDA.
This allows the slave device being addressed to
respond with an ACK bit during the ninth bit time if an
address match occurred, or if data was received prop-
erly. The status of ACK is written into the ACKDT bit on
the falling edge of the ninth clock. If the master receives
an Acknowledge, the Acknowledge Status bit,
ACKSTAT, is cleared. If not, the bit is set. After the ninth
clock, the SSPIF bit is set and the master clock (Baud
Rate Generator) is suspended until the next data byte
is loaded into the SSPBUF, leaving SCL low and SDA
unchanged (Figure 17-21).
17.4.11 I2C MASTER MODE RECEPTION
Master mode reception is enabled by programming the
Receive Enable bit, RCEN (SSPCON2<3>).
Note:
The MSSP module must be in an Idle state
before the RCEN bit is set or the RCEN bit
will be disregarded.
The Baud Rate Generator begins counting and on each
rollover, the state of the SCL pin changes (high-to-low/
low-to-high) and data is shifted into the SSPSR. After
the falling edge of the eighth clock, the receive enable
flag is automatically cleared, the contents of the
SSPSR are loaded into the SSPBUF, the BF flag bit is
set, the SSPIF flag bit is set and the Baud Rate Gener-
ator is suspended from counting, holding SCL low. The
MSSP is now in Idle state awaiting the next command.
When the buffer is read by the CPU, the BF flag bit is
automatically cleared. The user can then send an
Acknowledge bit at the end of reception by setting the
Acknowledge Sequence Enable bit, ACKEN
(SSPCON2<4>).
17.4.11.1 BF Status Flag
After the write to the SSPBUF, each bit of the address
will be shifted out on the falling edge of SCL until all
seven address bits and the R/W bit are completed. On
the falling edge of the eighth clock, the master will
deassert the SDA pin, allowing the slave to respond
with an Acknowledge. On the falling edge of the ninth
clock, the master will sample the SDA pin to see if the
address was recognized by a slave. The status of the
ACK bit is loaded into the ACKSTAT status bit
(SSPCON2<6>). Following the falling edge of the ninth
clock transmission of the address, the SSPIF is set, the
BF flag is cleared and the Baud Rate Generator is
turned off until another write to the SSPBUF takes
place, holding SCL low and allowing SDA to float.
In receive operation, the BF bit is set when an address
or data byte is loaded into SSPBUF from SSPSR. It is
cleared when the SSPBUF register is read.
17.4.11.2 SSPOV Status Flag
In receive operation, the SSPOV bit is set when 8 bits
are received into the SSPSR and the BF flag bit is
already set from a previous reception.
17.4.11.3 WCOL Status Flag
If the user writes the SSPBUF when a receive is
already in progress (i.e., SSPSR is still shifting in a data
byte), the WCOL bit is set and the contents of the buffer
are unchanged (the write doesn’t occur).
17.4.10.1 BF Status Flag
In Transmit mode, the BF bit (SSPSTAT<0>) is set
when the CPU writes to SSPBUF and is cleared when
all 8 bits are shifted out.
17.4.10.2 WCOL Status Flag
If the user writes the SSPBUF when a transmit is
already in progress (i.e., SSPSR is still shifting out a
data byte), the WCOL is set and the contents of the
buffer are unchanged (the write doesn’t occur).
WCOL must be cleared in software.
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2
FIGURE 17-21:
I C MASTER MODE WAVEFORM (TRANSMISSION, 7 OR 10-BIT ADDRESS)
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2
FIGURE 17-22:
I C MASTER MODE WAVEFORM (RECEPTION, 7-BIT ADDRESS)
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17.4.12 ACKNOWLEDGE SEQUENCE
TIMING
17.4.13 STOP CONDITION TIMING
A Stop bit is asserted on the SDA pin at the end of a
receive/transmit by setting the Stop Sequence Enable
bit, PEN (SSPCON2<2>). At the end of a receive/
transmit, the SCL line is held low after the falling edge
of the ninth clock. When the PEN bit is set, the master
will assert the SDA line low. When the SDA line is sam-
pled low, the Baud Rate Generator is reloaded and
counts down to ‘0’. When the Baud Rate Generator
times out, the SCL pin will be brought high and one
TBRG (Baud Rate Generator rollover count) later, the
SDA pin will be deasserted. When the SDA pin is sam-
pled high while SCL is high, the P bit (SSPSTAT<4>) is
set. A TBRG later, the PEN bit is cleared and the SSPIF
bit is set (Figure 17-24).
An Acknowledge sequence is enabled by setting the
Acknowledge Sequence Enable bit, ACKEN
(SSPCON2<4>). When this bit is set, the SCL pin is
pulled low and the contents of the Acknowledge data bit
are presented on the SDA pin. If the user wishes to gen-
erate an Acknowledge, then the ACKDT bit should be
cleared. If not, the user should set the ACKDT bit before
starting an Acknowledge sequence. The Baud Rate
Generator then counts for one rollover period (TBRG)
and the SCL pin is deasserted (pulled high). When the
SCL pin is sampled high (clock arbitration), the Baud
Rate Generator counts for TBRG. The SCL pin is then
pulled low. Following this, the ACKEN bit is automatically
cleared, the Baud Rate Generator is turned off and the
MSSP module then goes into Idle mode (Figure 17-23).
17.4.13.1 WCOL Status Flag
If the user writes the SSPBUF when a Stop sequence
is in progress, then the WCOL bit is set and the con-
tents of the buffer are unchanged (the write doesn’t
occur).
17.4.12.1 WCOL Status Flag
If the user writes the SSPBUF when an Acknowledge
sequence is in progress, then WCOL is set and the
contents of the buffer are unchanged (the write doesn’t
occur).
FIGURE 17-23:
ACKNOWLEDGE SEQUENCE WAVEFORM
Acknowledge sequence starts here,
write to SSPCON2
ACKEN automatically cleared
ACKEN = 1, ACKDT = 0
TBRG
ACK
TBRG
SDA
SCL
D0
8
9
SSPIF
Cleared in
SSPIF set at
the end of receive
software
Cleared in
software
SSPIF set at the end
of Acknowledge sequence
Note: TBRG = one Baud Rate Generator period.
FIGURE 17-24:
STOP CONDITION RECEIVE OR TRANSMIT MODE
SCL = 1for TBRG, followed by SDA = 1for TBRG
after SDA sampled high. P bit (SSPSTAT<4>) is set.
Write to SSPCON2,
set PEN
PEN bit (SSPCON2<2>) is cleared by
hardware and the SSPIF bit is set
Falling edge of
9th clock
TBRG
SCL
SDA
ACK
P
TBRG
TBRG
TBRG
SCL brought high after TBRG
SDA asserted low before rising edge of clock
to setup Stop condition
Note: TBRG = one Baud Rate Generator period.
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17.4.14 SLEEP OPERATION
17.4.17 MULTI -MASTER COMMUNICATION,
While in Sleep mode, the I2C module can receive
addresses or data and when an address match or com-
plete byte transfer occurs, wake the processor from
Sleep (if the MSSP interrupt is enabled).
BUS COLLISION AND BUS
ARBITRATION
Multi-Master mode support is achieved by bus arbitra-
tion. When the master outputs address/data bits onto
the SDA pin, arbitration takes place when the master
outputs a ‘1’ on SDA, by letting SDA float high and
another master asserts a ‘0’. When the SCL pin floats
high, data should be stable. If the expected data on
SDA is a ‘1’ and the data sampled on the SDA pin = 0,
then a bus collision has taken place. The master will set
the Bus Collision Interrupt Flag, BCLIF and reset the
I2C port to its Idle state (Figure 17-25).
17.4.15 EFFECTS OF A RESET
A Reset disables the MSSP module and terminates the
current transfer.
17.4.16 MULTI-MASTER MODE
In Multi-Master mode, the interrupt generation on the
detection of the Start and Stop conditions allows the
determination of when the bus is free. The Stop (P) and
Start (S) bits are cleared from a Reset or when the
MSSP module is disabled. Control of the I2C bus may
be taken when the P bit (SSPSTAT<4>) is set, or the
bus is Idle, with both the S and P bits clear. When the
bus is busy, enabling the SSP interrupt will generate
the interrupt when the Stop condition occurs.
If a transmit was in progress when the bus collision
occurred, the transmission is halted, the BF flag is
cleared, the SDA and SCL lines are deasserted and the
SSPBUF can be written to. When the user services the
bus collision Interrupt Service Routine and if the I2C
bus is free, the user can resume communication by
asserting a Start condition.
In multi-master operation, the SDA line must be
monitored for arbitration to see if the signal level is the
expected output level. This check is performed in
hardware with the result placed in the BCLIF bit.
If a Start, Repeated Start, Stop or Acknowledge condi-
tion was in progress when the bus collision occurred, the
condition is aborted, the SDA and SCL lines are deas-
serted and the respective control bits in the SSPCON2
register are cleared. When the user services the bus col-
lision Interrupt Service Routine and if the I2C bus is free,
the user can resume communication by asserting a Start
condition.
The states where arbitration can be lost are:
• Address Transfer
• Data Transfer
• A Start Condition
The master will continue to monitor the SDA and SCL
pins. If a Stop condition occurs, the SSPIF bit will be set.
• A Repeated Start Condition
• An Acknowledge Condition
A write to the SSPBUF will start the transmission of
data at the first data bit, regardless of where the
transmitter left off when the bus collision occurred.
In Multi-Master mode, the interrupt generation on the
detection of Start and Stop conditions allows the deter-
mination of when the bus is free. Control of the I2C bus
can be taken when the P bit is set in the SSPSTAT
register, or the bus is Idle and the S and P bits are
cleared.
FIGURE 17-25:
BUS COLLISION TIMING FOR TRANSMIT AND ACKNOWLEDGE
Sample SDA. While SCL is high,
data doesn’t match what is driven
by the master.
Data changes
while SCL = 0
SDA line pulled low
by another source
Bus collision has occurred.
SDA released
by master
SDA
SCL
Set bus collision
interrupt (BCLIF)
BCLIF
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If the SDA pin is sampled low during this count, the
17.4.17.1 Bus Collision During a Start
Condition
BRG is reset and the SDA line is asserted early
(Figure 17-28). If, however, a ‘1’ is sampled on the SDA
pin, the SDA pin is asserted low at the end of the BRG
count. The Baud Rate Generator is then reloaded and
counts down to 0; if the SCL pin is sampled as ‘0’
during this time, a bus collision does not occur. At the
end of the BRG count, the SCL pin is asserted low.
During a Start condition, a bus collision occurs if:
a) SDA or SCL are sampled low at the beginning of
the Start condition (Figure 17-26).
b) SCL is sampled low before SDA is asserted low
(Figure 17-27).
During a Start condition, both the SDA and the SCL
pins are monitored.
Note:
The reason that bus collision is not a factor
during a Start condition is that no two bus
masters can assert a Start condition at the
exact same time. Therefore, one master
will always assert SDA before the other.
This condition does not cause a bus colli-
sion because the two masters must be
allowed to arbitrate the first address fol-
lowing the Start condition. If the address is
the same, arbitration must be allowed to
continue into the data portion, Repeated
Start or Stop conditions.
If the SDA pin is already low, or the SCL pin is already
low, then all of the following occur:
• the Start condition is aborted,
• the BCLIF flag is set and
•
the MSSP module is reset to its Idle state
(Figure 17-26).
The Start condition begins with the SDA and SCL pins
deasserted. When the SDA pin is sampled high, the
Baud Rate Generator is loaded from SSPADD<6:0>
and counts down to 0. If the SCL pin is sampled low
while SDA is high, a bus collision occurs because it is
assumed that another master is attempting to drive a
data ‘1’ during the Start condition.
FIGURE 17-26:
BUS COLLISION DURING START CONDITION (SDA ONLY)
SDA goes low before the SEN bit is set.
Set BCLIF,
S bit and SSPIF set because
SDA = 0, SCL = 1.
SDA
SCL
SEN
Set SEN, enable Start
condition if SDA = 1, SCL = 1
SEN cleared automatically because of bus collision.
SSP module reset into Idle state.
SDA sampled low before
Start condition. Set BCLIF.
S bit and SSPIF set because
SDA = 0, SCL = 1.
BCLIF
SSPIF and BCLIF are
cleared in software
S
SSPIF
SSPIF and BCLIF are
cleared in software
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FIGURE 17-27:
BUS COLLISION DURING START CONDITION (SCL = 0)
SDA = 0, SCL = 1
TBRG
TBRG
SDA
Set SEN, enable Start
sequence if SDA = 1, SCL = 1
SCL
SEN
SCL = 0before SDA = 0,
bus collision occurs. Set BCLIF.
SCL = 0before BRG time-out,
bus collision occurs. Set BCLIF.
BCLIF
Interrupt cleared
in software
S
‘0’
‘0’
‘0’
‘0’
SSPIF
FIGURE 17-28:
BRG RESET DUE TO SDA ARBITRATION DURING START CONDITION
SDA = 0, SCL = 1
Set S
Set SSPIF
Less than TBRG
TBRG
SDA pulled low by other master.
Reset BRG and assert SDA.
SDA
SCL
S
SCL pulled low after BRG
time-out
SEN
Set SEN, enable START
sequence if SDA = 1, SCL = 1
‘0’
BCLIF
S
SSPIF
Interrupts cleared
in software
SDA = 0, SCL = 1,
set SSPIF
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If SDA is low, a bus collision has occurred (i.e., another
17.4.17.2 Bus Collision During a Repeated
Start Condition
master is attempting to transmit a data ‘0’, Figure 17-29).
If SDA is sampled high, the BRG is reloaded and begins
counting. If SDA goes from high-to-low before the BRG
times out, no bus collision occurs because no two
masters can assert SDA at exactly the same time.
During a Repeated Start condition, a bus collision
occurs if:
a) A low level is sampled on SDA when SCL goes
from low level to high level.
If SCL goes from high-to-low before the BRG times out
and SDA has not already been asserted, a bus collision
occurs. In this case, another master is attempting to
transmit a data ‘1’ during the Repeated Start condition,
see Figure 17-30.
b) SCL goes low before SDA is asserted low,
indicating that another master is attempting to
transmit a data ‘1’.
When the user deasserts SDA and the pin is allowed to
float high, the BRG is loaded with SSPADD<6:0> and
counts down to 0. The SCL pin is then deasserted and
when sampled high, the SDA pin is sampled.
If, at the end of the BRG time-out, both SCL and SDA
are still high, the SDA pin is driven low and the BRG is
reloaded and begins counting. At the end of the count,
regardless of the status of the SCL pin, the SCL pin is
driven low and the Repeated Start condition is
complete.
FIGURE 17-29:
BUS COLLISION DURING A REPEATED START CONDITION (CASE 1)
SDA
SCL
Sample SDA when SCL goes high.
If SDA = 0, set BCLIF and release SDA and SCL.
RSEN
BCLIF
Cleared in software
‘0’
S
‘0’
SSPIF
FIGURE 17-30:
BUS COLLISION DURING REPEATED START CONDITION (CASE 2)
TBRG
TBRG
SDA
SCL
SCL goes low before SDA,
BCLIF
RSEN
set BCLIF. Release SDA and SCL.
Interrupt cleared
in software
‘0’
S
SSPIF
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The Stop condition begins with SDA asserted low.
When SDA is sampled low, the SCL pin is allowed to
float. When the pin is sampled high (clock arbitration),
the Baud Rate Generator is loaded with SSPADD<6:0>
and counts down to 0. After the BRG times out, SDA is
sampled. If SDA is sampled low, a bus collision has
occurred. This is due to another master attempting to
drive a data ‘0’ (Figure 17-31). If the SCL pin is
sampled low before SDA is allowed to float high, a bus
collision occurs. This is another case of another master
attempting to drive a data ‘0’ (Figure 17-32).
17.4.17.3 Bus Collision During a Stop
Condition
Bus collision occurs during a Stop condition if:
a) After the SDA pin has been deasserted and
allowed to float high, SDA is sampled low after
the BRG has timed out.
b) After the SCL pin is deasserted, SCL is sampled
low before SDA goes high.
FIGURE 17-31:
BUS COLLISION DURING A STOP CONDITION (CASE 1)
SDA sampled
low after TBRG,
set BCLIF
TBRG
TBRG
TBRG
SDA
SDA asserted low
SCL
PEN
BCLIF
P
‘0’
‘0’
SSPIF
FIGURE 17-32:
BUS COLLISION DURING A STOP CONDITION (CASE 2)
TBRG
TBRG
TBRG
SDA
SCL goes low before SDA goes high,
set BCLIF
Assert SDA
SCL
PEN
BCLIF
P
‘0’
‘0’
SSPIF
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NOTES:
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The pins of the Enhanced USART are multiplexed
with PORTC. In order to configure RC6/TX/CK and
RC7/RX/DT as a USART:
18.0 ENHANCED UNIVERSAL
SYNCHRONOUS RECEIVER
TRANSMITTER (EUSART)
• bit SPEN (RCSTA<7>) must be set (= 1)
• bit TRISC<7> must be set (= 1)
• bit TRISC<6> must be set (= 1)
The Enhanced Universal Synchronous Asynchronous
Receiver Transmitter (EUSART) module is one of the
two serial I/O modules. (Generically, the USART is also
known as a Serial Communications Interface or SCI.)
The EUSART can be configured as a full-duplex
asynchronous system that can communicate with
peripheral devices, such as CRT terminals and
personal computers. It can also be configured as a half-
duplex synchronous system that can communicate
with peripheral devices, such as A/D or D/A integrated
circuits, serial EEPROMs, etc.
Note:
The EUSART control will automatically
reconfigure the pin from input to output as
needed.
The operation of the Enhanced USART module is
controlled through three registers:
• Transmit Status and Control (TXSTA)
• Receive Status and Control (RCSTA)
• Baud Rate Control (BAUDCON)
The Enhanced USART module implements additional
features, including automatic baud rate detection and
calibration, automatic wake-up on Sync Break recep-
tion and 12-bit Break character transmit. These make it
ideally suited for use in Local Interconnect Network bus
(LIN bus) systems.
These are detailed on the following pages in
Register 18-1, Register 18-2 and Register 18-3,
respectively.
The EUSART can be configured in the following
modes:
• Asynchronous (full duplex) with:
- Auto-wake-up on character reception
- Auto-baud calibration
- 12-bit Break character transmission
• Synchronous – Master (half duplex) with
selectable clock polarity
• Synchronous – Slave (half duplex) with selectable
clock polarity
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REGISTER 18-1: TXSTA: TRANSMIT STATUS AND CONTROL REGISTER
R/W-0
CSRC
R/W-0
TX9
R/W-0
TXEN
R/W-0
SYNC
R/W-0
R/W-0
BRGH
R-1
R/W-0
TX9D
SENDB
TRMT
bit 7
bit 0
bit 7
CSRC: Clock Source Select bit
Asynchronous mode:
Don’t care.
Synchronous mode:
1= Master mode (clock generated internally from BRG)
0= Slave mode (clock from external source)
bit 6
bit 5
TX9: 9-bit Transmit Enable bit
1= Selects 9-bit transmission
0= Selects 8-bit transmission
TXEN: Transmit Enable bit
1= Transmit enabled
0= Transmit disabled
Note:
SREN/CREN overrides TXEN in Sync mode.
bit 4
bit 3
SYNC: EUSART Mode Select bit
1= Synchronous mode
0= Asynchronous mode
SENDB: Send Break Character bit
Asynchronous mode:
1= Send Sync Break on next transmission (cleared by hardware upon completion)
0= Sync Break transmission completed
Synchronous mode:
Don’t care.
bit 2
BRGH: High Baud Rate Select bit
Asynchronous mode:
1= High speed
0= Low speed
Synchronous mode:
Unused in this mode.
bit 1
bit 0
TRMT: Transmit Shift Register Status bit
1= TSR empty
0= TSR full
TX9D: 9th bit of Transmit Data
Can be address/data bit or a parity bit.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
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REGISTER 18-2: RCSTA: RECEIVE STATUS AND CONTROL REGISTER
R/W-0
SPEN
R/W-0
RX9
R/W-0
SREN
R/W-0
CREN
R/W-0
R-0
R-0
R-x
ADDEN
FERR
OERR
RX9D
bit 7
bit 0
bit 7
bit 6
bit 5
SPEN: Serial Port Enable bit
1= Serial port enabled (configures RX/DT and TX/CK pins as serial port pins)
0= Serial port disabled (held in Reset)
RX9: 9-bit Receive Enable bit
1= Selects 9-bit reception
0= Selects 8-bit reception
SREN: Single Receive Enable bit
Asynchronous mode:
Don’t care.
Synchronous mode – Master:
1= Enables single receive
0= Disables single receive
This bit is cleared after reception is complete.
Synchronous mode – Slave:
Don’t care.
bit 4
CREN: Continuous Receive Enable bit
Asynchronous mode:
1= Enables receiver
0= Disables receiver
Synchronous mode:
1= Enables continuous receive until enable bit CREN is cleared (CREN overrides SREN)
0= Disables continuous receive
bit 3
ADDEN: Address Detect Enable bit
Asynchronous mode 9-bit (RX9 = 1):
1= Enables address detection, enables interrupt and loads the receive buffer when RSR<8>
is set
0= Disables address detection, all bytes are received and ninth bit can be used as parity bit
Asynchronous mode 9-bit (RX9 = 0):
Don’t care.
bit 2
bit 1
bit 0
FERR: Framing Error bit
1= Framing error (can be updated by reading RCREG register and receiving next valid byte)
0= No framing error
OERR: Overrun Error bit
1= Overrun error (can be cleared by clearing bit CREN)
0= No overrun error
RX9D: 9th bit of Received Data
This can be address/data bit or a parity bit and must be calculated by user firmware.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
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REGISTER 18-3: BAUDCON: BAUD RATE CONTROL REGISTER
R/W-0
ABDOVF
bit 7
R-1
U-0
—
R/W-0
SCKP
R/W-0
U-0
—
R/W-0
WUE
R/W-0
RCIDL
BRG16
ABDEN
bit 0
bit 7
bit 6
ABDOVF: Auto-Baud Acquisition Rollover Status bit
1= A BRG rollover has occurred during Auto-Baud Rate Detect mode
(must be cleared in software)
0= No BRG rollover has occurred
RCIDL: Receive Operation Idle Status bit
1= Receive operation is Idle
0= Receive operation is active
bit 5
bit 4
Unimplemented: Read as ‘0’
SCKP: Synchronous Clock Polarity Select bit
Asynchronous mode:
Unused in this mode.
Synchronous mode:
1= Idle state for clock (CK) is a high level
0= Idle state for clock (CK) is a low level
bit 3
BRG16: 16-bit Baud Rate Register Enable bit
1= 16-bit Baud Rate Generator – SPBRGH and SPBRG
0= 8-bit Baud Rate Generator – SPBRG only (Compatible mode), SPBRGH value ignored
bit 2
bit 1
Unimplemented: Read as ‘0’
WUE: Wake-up Enable bit
Asynchronous mode:
1= EUSART will continue to sample the RX pin – interrupt generated on falling edge; bit
cleared in hardware on following rising edge
0= RX pin not monitored or rising edge detected
Synchronous mode:
Unused in this mode.
bit 0
ABDEN: Auto-Baud Detect Enable bit
Asynchronous mode:
1= Enable baud rate measurement on the next character. Requires reception of a Sync field
(55h); cleared in hardware upon completion
0= Baud rate measurement disabled or completed
Synchronous mode:
Unused in this mode.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS39631A-page 204
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
tageous to use the high baud rate (BRGH = 1) or the
16-bit BRG to reduce the baud rate error, or achieve a
18.1
Baud Rate Generator (BRG)
The BRG is a dedicated 8-bit or 16-bit generator that
supports both the Asynchronous and Synchronous
modes of the EUSART. By default, the BRG operates
in 8-bit mode; setting the BRG16 bit (BAUDCON<3>)
selects 16-bit mode.
slow baud rate for a fast oscillator frequency.
Writing a new value to the SPBRGH:SPBRG registers
causes the BRG timer to be reset (or cleared). This
ensures the BRG does not wait for a timer overflow
before outputting the new baud rate.
The SPBRGH:SPBRG register pair controls the period
of a free running timer. In Asynchronous mode, bits
BRGH (TXSTA<2>) and BRG16 (BAUDCON<3>) also
control the baud rate. In Synchronous mode, BRGH is
ignored. Table 18-1 shows the formula for computation
of the baud rate for different EUSART modes which
only apply in Master mode (internally generated clock).
18.1.1
OPERATION IN POWER MANAGED
MODES
The device clock is used to generate the desired baud
rate. When one of the power managed modes is
entered, the new clock source may be operating at a
different frequency. This may require an adjustment to
the value in the SPBRG register pair.
Given the desired baud rate and FOSC, the nearest
integer value for the SPBRGH:SPBRG registers can be
calculated using the formulas in Table 18-1. From this,
the error in baud rate can be determined. An example
calculation is shown in Example 18-1. Typical baud
rates and error values for the various Asynchronous
modes are shown in Table 18-2. It may be advan-
18.1.2
SAMPLING
The data on the RX pin is sampled three times by a
majority detect circuit to determine if a high or a low
level is present at the RX pin.
TABLE 18-1: BAUD RATE FORMULAS
Configuration Bits
BRG/EUSART Mode
Baud Rate Formula
SYNC
BRG16
BRGH
0
0
0
0
1
1
0
0
1
1
0
1
0
1
0
1
x
x
8-bit/Asynchronous
8-bit/Asynchronous
16-bit/Asynchronous
16-bit/Asynchronous
8-bit/Synchronous
16-bit/Synchronous
FOSC/[64 (n + 1)]
FOSC/[16 (n + 1)]
FOSC/[4 (n + 1)]
Legend: x= Don’t care, n = value of SPBRGH:SPBRG register pair
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 205
PIC18F2420/2520/4420/4520
EXAMPLE 18-1:
CALCULATING BAUD RATE ERROR
For a device with FOSC of 16 MHz, desired baud rate of 9600, Asynchronous mode, 8-bit BRG:
Desired Baud Rate FOSC/(64 ([SPBRGH:SPBRG] + 1))
Solving for SPBRGH:SPBRG:
=
X
=
=
=
=
=
=
=
((FOSC/Desired Baud Rate)/64) – 1
((16000000/9600)/64) – 1
[25.042] = 25
16000000/(64 (25 + 1))
9615
Calculated Baud Rate
Error
(Calculated Baud Rate – Desired Baud Rate)/Desired Baud Rate
(9615 – 9600)/9600 = 0.16%
TABLE 18-2: REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR
Reset Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TXSTA
RCSTA
CSRC
SPEN
TX9
RX9
TXEN
SREN
—
SYNC
CREN
SCKP
SENDB
ADDEN
BRG16
BRGH
FERR
—
TRMT
OERR
WUE
TX9D
RX9D
51
51
51
51
51
BAUDCON ABDOVF RCIDL
ABDEN
SPBRGH EUSART Baud Rate Generator Register, High Byte
SPBRG EUSART Baud Rate Generator Register, Low Byte
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the BRG.
DS39631A-page 206
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 18-3: BAUD RATES FOR ASYNCHRONOUS MODES
SYNC = 0, BRGH = 0, BRG16 = 0
BAUD
RATE
(K)
FOSC = 40.000 MHz
FOSC = 20.000 MHz FOSC = 10.000 MHz
FOSC = 8.000 MHz
Actual
Rate
(K)
SPBRG Actual
value
SPBRG Actual
SPBRG Actual
value
(decimal)
SPBRG
value
(decimal)
%
%
Error
%
Error
%
Error
Rate
(K)
value
Rate
(K)
Rate
(K)
Error
(decimal)
(decimal)
0.3
1.2
—
—
—
—
—
—
—
255
129
31
15
4
—
—
—
129
64
15
7
—
1201
2403
9615
—
—
-0.16
-0.16
-0.16
—
—
103
51
12
—
—
—
1.221
1.73
0.16
1.73
1.73
8.51
-9.58
1.202
2.404
9.766
19.531
52.083
78.125
0.16
0.16
1.73
1.73
-9.58
-32.18
2.4
2.441
9.615
19.531
56.818
125.000
1.73
0.16
1.73
-1.36
8.51
255
64
31
10
4
2.404
9.6
9.766
19.2
57.6
115.2
19.531
62.500
104.167
2
—
—
—
2
1
—
—
—
SYNC = 0, BRGH = 0, BRG16 = 0
BAUD
RATE
(K)
FOSC = 4.000 MHz
FOSC = 2.000 MHz
FOSC = 1.000 MHz
Actual
Rate
(K)
SPBRG Actual
value
SPBRG Actual
value
(decimal)
SPBRG
value
(decimal)
%
%
Error
%
Error
Rate
(K)
Rate
(K)
Error
(decimal)
0.3
1.2
0.300
1.202
0.16
0.16
207
51
25
6
300
1201
2403
—
-0.16
-0.16
-0.16
—
103
25
12
—
300
1201
—
-0.16
-0.16
—
51
12
—
—
—
—
—
2.4
2.404
0.16
9.6
8.929
-6.99
8.51
—
—
19.2
57.6
115.2
20.833
62.500
62.500
2
—
—
—
—
—
8.51
0
—
—
—
—
—
-45.75
0
—
—
—
—
—
SYNC = 0, BRGH = 1, BRG16 = 0
BAUD
RATE
(K)
FOSC = 40.000 MHz
FOSC = 20.000 MHz
FOSC = 10.000 MHz
FOSC = 8.000 MHz
Actual
Rate
(K)
SPBRG Actual
value
(decimal)
SPBRG Actual
value
(decimal)
SPBRG Actual
value
(decimal)
SPBRG
value
%
Error
%
Error
%
Error
%
Error
Rate
(K)
Rate
(K)
Rate
(K)
(decimal)
0.3
1.2
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
2.4
—
—
—
—
—
—
2.441
9.615
19.531
56.818
125.000
1.73
0.16
1.73
-1.36
8.51
255
64
31
10
4
2403
9615
19230
55555
—
-0.16
-0.16
-0.16
3.55
—
207
51
25
8
9.6
9.766
19.231
58.140
113.636
1.73
0.16
0.94
-1.36
255
129
42
9.615
19.231
56.818
113.636
0.16
0.16
-1.36
-1.36
129
64
21
10
19.2
57.6
115.2
21
—
SYNC = 0, BRGH = 1, BRG16 = 0
BAUD
RATE
(K)
FOSC = 4.000 MHz
FOSC = 2.000 MHz
FOSC = 1.000 MHz
Actual
Rate
(K)
SPBRG Actual
value
SPBRG Actual
value
(decimal)
SPBRG
value
(decimal)
%
%
Error
%
Error
Rate
(K)
Rate
(K)
Error
(decimal)
0.3
1.2
—
—
—
207
103
25
12
3
—
1201
2403
9615
—
—
-0.16
-0.16
-0.16
—
—
103
51
12
—
300
1201
2403
—
-0.16
-0.16
-0.16
—
207
51
25
—
1.202
0.16
0.16
0.16
0.16
8.51
8.51
2.4
2.404
9.6
9.615
19.2
57.6
115.2
19.231
62.500
125.000
—
—
—
—
—
—
—
—
—
1
—
—
—
—
—
—
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 207
PIC18F2420/2520/4420/4520
TABLE 18-3: BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED)
SYNC = 0, BRGH = 0, BRG16 = 1
BAUD
RATE
(K)
FOSC = 40.000 MHz
FOSC = 20.000 MHz
FOSC = 10.000 MHz
FOSC = 8.000 MHz
Actual
Rate
(K)
SPBRG Actual
value
SPBRG Actual
value
(decimal)
SPBRG Actual
value
(decimal)
SPBRG
value
(decimal)
%
%
Error
%
Error
%
Error
Rate
(K)
Rate
(K)
Rate
(K)
Error
(decimal)
0.3
1.2
0.300
1.200
0.00
0.02
0.06
0.16
0.16
0.94
-1.36
8332
2082
1040
259
129
42
0.300
1.200
0.02
-0.03
-0.03
0.16
4165
1041
520
129
64
0.300
1.200
0.02
-0.03
0.16
0.16
1.73
-1.36
8.51
2082
520
259
64
300
1201
2403
9615
19230
55555
—
-0.04
-0.16
-0.16
-0.16
-0.16
3.55
—
1665
415
207
51
2.4
2.402
2.399
2.404
9.6
9.615
9.615
9.615
19.2
57.6
115.2
19.231
58.140
113.636
19.231
56.818
113.636
0.16
19.531
56.818
125.000
31
25
-1.36
-1.36
21
10
8
21
10
4
—
SYNC = 0, BRGH = 0, BRG16 = 1
BAUD
RATE
(K)
FOSC = 4.000 MHz
FOSC = 2.000 MHz
FOSC = 1.000 MHz
Actual
Rate
(K)
SPBRG Actual
value
SPBRG Actual
value
(decimal)
SPBRG
value
(decimal)
%
%
Error
%
Error
Rate
(K)
Rate
(K)
Error
(decimal)
0.3
1.2
0.300
1.202
0.04
0.16
0.16
0.16
0.16
8.51
8.51
832
207
103
25
12
3
300
1201
2403
9615
—
-0.16
-0.16
-0.16
-0.16
—
415
103
51
12
—
300
1201
2403
—
-0.16
-0.16
-0.16
—
207
51
25
—
2.4
2.404
9.6
9.615
19.2
57.6
115.2
19.231
62.500
125.000
—
—
—
—
—
—
—
—
—
1
—
—
—
—
—
—
SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1
FOSC = 20.000 MHz FOSC = 10.000 MHz
BAUD
RATE
(K)
FOSC = 40.000 MHz
FOSC = 8.000 MHz
Actual
Rate
(K)
SPBRG Actual
SPBRG Actual
SPBRG Actual
value
SPBRG
value
(decimal)
%
Error
%
%
%
Error
value
(decimal)
Rate
(K)
value
Rate
(K)
Rate
(K)
Error
Error
(decimal)
(decimal)
0.3
1.2
0.300
1.200
0.00
0.00
0.02
0.06
-0.03
0.35
-0.22
33332
8332
4165
1040
520
0.300
1.200
0.00
0.02
0.02
-0.03
0.16
-0.22
0.94
16665
4165
2082
520
259
86
0.300
1.200
0.00
0.02
0.06
0.16
0.16
0.94
-1.36
8332
2082
1040
259
129
42
300
1200
-0.01
-0.04
-0.04
-0.16
-0.16
0.79
6665
1665
832
207
103
34
2.4
2.400
2.400
2.402
2400
9.6
9.606
9.596
9.615
9615
19.2
57.6
115.2
19.193
57.803
114.943
19.231
57.471
116.279
19.231
58.140
113.636
19230
57142
117647
172
86
42
21
-2.12
16
SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1
FOSC = 4.000 MHz FOSC = 2.000 MHz FOSC = 1.000 MHz
BAUD
RATE
(K)
Actual
Rate
(K)
SPBRG Actual
SPBRG Actual
SPBRG
value
(decimal)
%
Error
%
Error
%
Error
value
Rate
(K)
value
Rate
(K)
(decimal)
(decimal)
0.3
1.2
0.300
1.200
0.01
0.04
0.16
0.16
0.16
2.12
-3.55
3332
832
415
103
51
300
1201
2403
9615
19230
55555
—
-0.04
-0.16
-0.16
-0.16
-0.16
3.55
—
1665
415
207
51
300
1201
2403
9615
19230
—
-0.04
-0.16
-0.16
-0.16
-0.16
—
832
207
103
25
2.4
2.404
9.6
9.615
19.2
57.6
115.2
19.231
58.824
111.111
25
12
16
8
—
8
—
—
—
—
DS39631A-page 208
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
18.1.3
AUTO-BAUD RATE DETECT
Note 1: If the WUE bit is set with the ABDEN bit,
Auto-Baud Rate Detection will occur on
the byte following the Break character.
The enhanced USART module supports the automatic
detection and calibration of baud rate. This feature is
active only in Asynchronous mode and while the WUE
bit is clear.
2: It is up to the user to determine that the
incoming character baud rate is within the
range of the selected BRG clock source.
Some combinations of oscillator frequency
and EUSART baud rates are not possible
due to bit error rates. Overall system tim-
ing and communication baud rates must
be taken into consideration when using the
Auto-Baud Rate Detection feature.
The automatic baud rate measurement sequence
(Figure 18-1) begins whenever a Start bit is received
and the ABDEN bit is set. The calculation is
self-averaging.
In the Auto-Baud Rate Detect (ABD) mode, the clock to
the BRG is reversed. Rather than the BRG clocking the
incoming RX signal, the RX signal is timing the BRG. In
ABD mode, the internal Baud Rate Generator is used
as a counter to time the bit period of the incoming serial
byte stream.
TABLE 18-4: BRG COUNTER
CLOCK RATES
Once the ABDEN bit is set, the state machine will clear
the BRG and look for a Start bit. The Auto-Baud Rate
Detect must receive a byte with the value 55h (ASCII
“U”, which is also the LIN bus Sync character) in order to
calculate the proper bit rate. The measurement is taken
over both a low and a high bit time in order to minimize
any effects caused by asymmetry of the incoming signal.
After a Start bit, the SPBRG begins counting up, using
the preselected clock source on the first rising edge of
RX. After eight bits on the RX pin or the fifth rising edge,
an accumulated value totalling the proper BRG period is
left in the SPBRGH:SPBRG register pair. Once the 5th
edge is seen (this should correspond to the Stop bit), the
ABDEN bit is automatically cleared.
BRG16 BRGH
BRG Counter Clock
0
0
1
1
0
1
0
1
FOSC/512
FOSC/128
FOSC/128
FOSC/32
Note: During the ABD sequence, SPBRG and
SPBRGH are both used as a 16-bit counter,
independent of BRG16 setting.
18.1.3.1
ABD and EUSART Transmission
Since the BRG clock is reversed during ABD acquisi-
tion, the EUSART transmitter cannot be used during
ABD. This means that whenever the ABDEN bit is set,
TXREG cannot be written to. Users should also ensure
that ABDEN does not become set during a transmit
sequence. Failing to do this may result in unpredictable
EUSART operation.
If a rollover of the BRG occurs (an overflow from FFFFh
to 0000h), the event is trapped by the ABDOVF status
bit (BAUDCON<7>). It is set in hardware by BRG roll-
overs and can be set or cleared by the user in software.
ABD mode remains active after rollover events and the
ABDEN bit remains set (Figure 18-2).
While calibrating the baud rate period, the BRG regis-
ters are clocked at 1/8th the preconfigured clock rate.
Note that the BRG clock will be configured by the
BRG16 and BRGH bits. Independent of the BRG16 bit
setting, both the SPBRG and SPBRGH will be used as
a 16-bit counter. This allows the user to verify that no
carry occurred for 8-bit modes by checking for 00h in
the SPBRGH register. Refer to Table 18-4 for counter
clock rates to the BRG.
While the ABD sequence takes place, the EUSART
state machine is held in Idle. The RCIF interrupt is set
once the fifth rising edge on RX is detected. The value
in the RCREG needs to be read to clear the RCIF
interrupt. ThecontentsofRCREG shouldbediscarded.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 209
PIC18F2420/2520/4420/4520
FIGURE 18-1:
AUTOMATIC BAUD RATE CALCULATION
BRG Value
RX pin
XXXXh
0000h
001Ch
Edge #5
Stop Bit
Edge #2
Bit 3
Edge #3
Bit 5
Edge #4
Bit 7
Bit 6
Edge #1
Bit 1
Start
Bit 0
Bit 2
Bit 4
BRG Clock
Auto-Cleared
Set by User
ABDEN bit
RCIF bit
(Interrupt)
Read
RCREG
XXXXh
XXXXh
1Ch
00h
SPBRG
SPBRGH
Note: The ABD sequence requires the EUSART module to be configured in Asynchronous mode and WUE = 0.
FIGURE 18-2:
BRG OVERFLOW SEQUENCE
BRG Clock
ABDEN bit
RX pin
Start
Bit 0
ABDOVF bit
BRG Value
FFFFh
XXXXh
0000h
0000h
DS39631A-page 210
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
Once the TXREG register transfers the data to the TSR
18.2 EUSART Asynchronous Mode
register (occurs in one TCY), the TXREG register is empty
and the TXIF flag bit (PIR1<4>) is set. This interrupt can
be enabled or disabled by setting or clearing the interrupt
enable bit, TXIE (PIE1<4>). TXIF will be set regardless of
the state of TXIE; it cannot be cleared in software. TXIF
is also not cleared immediately upon loading TXREG, but
becomes valid in the second instruction cycle following
the load instruction. Polling TXIF immediately following a
load of TXREG will return invalid results.
The Asynchronous mode of operation is selected by
clearing the SYNC bit (TXSTA<4>). In this mode, the
EUSART uses standard Non-Return-to-Zero (NRZ) for-
mat (one Start bit, eight or nine data bits and one Stop
bit). The most common data format is 8 bits. An on-chip
dedicated 8-bit/16-bit Baud Rate Generator can be used
to derive standard baud rate frequencies from the
oscillator.
The EUSART transmits and receives the LSb first. The
EUSART’s transmitter and receiver are functionally
independent but use the same data format and baud
rate. The Baud Rate Generator produces a clock, either
x16 or x64 of the bit shift rate depending on the BRGH
and BRG16 bits (TXSTA<2> and BAUDCON<3>). Parity
is not supported by the hardware but can be
implemented in software and stored as the 9th data bit.
While TXIF indicates the status of the TXREG register,
another bit, TRMT (TXSTA<1>), shows the status of
the TSR register. TRMT is a read-only bit which is set
when the TSR register is empty. No interrupt logic is
tied to this bit so the user has to poll this bit in order to
determine if the TSR register is empty.
Note 1: The TSR register is not mapped in data
When operating in Asynchronous mode, the EUSART
module consists of the following important elements:
memory so it is not available to the user.
2: Flag bit TXIF is set when enable bit TXEN
• Baud Rate Generator
is set.
• Sampling Circuit
To set up an Asynchronous Transmission:
• Asynchronous Transmitter
• Asynchronous Receiver
1. Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRGH
and BRG16 bits, as required, to achieve the
desired baud rate.
• Auto-Wake-up on Sync Break Character
• 12-bit Break Character Transmit
• Auto-Baud Rate Detection
2. Enable the asynchronous serial port by clearing
bit SYNC and setting bit SPEN.
18.2.1
EUSART ASYNCHRONOUS
TRANSMITTER
3. If interrupts are desired, set enable bit TXIE.
4. If 9-bit transmission is desired, set transmit bit
TX9. Can be used as address/data bit.
The EUSART transmitter block diagram is shown in
Figure 18-3. The heart of the transmitter is the Transmit
(Serial) Shift Register (TSR). The Shift register obtains
its data from the Read/Write Transmit Buffer register,
TXREG. The TXREG register is loaded with data in
software. The TSR register is not loaded until the Stop
bit has been transmitted from the previous load. As
soon as the Stop bit is transmitted, the TSR is loaded
with new data from the TXREG register (if available).
5. Enable the transmission by setting bit TXEN
which will also set bit TXIF.
6. If 9-bit transmission is selected, the ninth bit
should be loaded in bit TX9D.
7. Load data to the TXREG register (starts
transmission).
8. If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
FIGURE 18-3:
EUSART TRANSMIT BLOCK DIAGRAM
Data Bus
TXREG Register
TXIF
TXIE
8
MSb
(8)
LSb
Pin Buffer
and Control
TX pin
0
•
•
•
TSR Register
Interrupt
Baud Rate CLK
SPBRG
TXEN
TRMT
SPEN
BRG16
SPBRGH
TX9
Baud Rate Generator
TX9D
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 211
PIC18F2420/2520/4420/4520
FIGURE 18-4:
ASYNCHRONOUS TRANSMISSION
Write to TXREG
Word 1
BRG Output
(Shift Clock)
TX (pin)
Start bit
bit 0
bit 1
Word 1
bit 7/8
Stop bit
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
1 TCY
Word 1
Transmit Shift Reg
TRMT bit
(Transmit Shift
Reg. Empty Flag)
FIGURE 18-5:
ASYNCHRONOUS TRANSMISSION (BACK TO BACK)
Write to TXREG
Word 2
Start bit
Word 1
BRG Output
(Shift Clock)
TX (pin)
Start bit
Word 2
bit 0
bit 1
bit 7/8
bit 0
Stop bit
1 TCY
Word 1
TXIF bit
(Interrupt Reg. Flag)
1 TCY
Word 1
Transmit Shift Reg.
Word 2
Transmit Shift Reg.
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Note: This timing diagram shows two consecutive transmissions.
TABLE 18-5: REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
PIR1
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
TXIF
RBIE
SSPIF
SSPIE
SSPIP
ADDEN
TMR0IF
CCP1IF
INT0IF
RBIF
49
52
52
52
51
51
51
51
51
51
PSPIF(1)
PSPIE(1)
PSPIP(1)
SPEN
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
TMR2IF
TMR1IF
PIE1
TXIE
CCP1IE TMR2IE TMR1IE
CCP1IP TMR2IP TMR1IP
IPR1
TXIP
RCSTA
TXREG
TXSTA
BAUDCON
SPBRGH
SPBRG
CREN
FERR
OERR
RX9D
EUSART Transmit Register
CSRC
TX9
TXEN
—
SYNC
SCKP
SENDB
BRG16
BRGH
—
TRMT
WUE
TX9D
ABDOVF
RCIDL
ABDEN
EUSART Baud Rate Generator Register, High Byte
EUSART Baud Rate Generator Register, Low Byte
Legend: — = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous transmission.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
DS39631A-page 212
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
18.2.2
EUSART ASYNCHRONOUS
RECEIVER
18.2.3
SETTING UP 9-BIT MODE WITH
ADDRESS DETECT
The receiver block diagram is shown in Figure 18-6.
The data is received on the RX pin and drives the data
recovery block. The data recovery block is actually a
high-speed shifter operating at x16 times the baud rate,
whereas the main receive serial shifter operates at the
bit rate or at FOSC. This mode would typically be used
in RS-232 systems.
This mode would typically be used in RS-485 systems.
To set up an Asynchronous Reception with Address
Detect Enable:
1. Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRGH
and BRG16 bits, as required, to achieve the
desired baud rate.
To set up an Asynchronous Reception:
2. Enable the asynchronous serial port by clearing
the SYNC bit and setting the SPEN bit.
1. Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRGH
and BRG16 bits, as required, to achieve the
desired baud rate.
3. If interrupts are required, set the RCEN bit and
select the desired priority level with the RCIP bit.
4. Set the RX9 bit to enable 9-bit reception.
5. Set the ADDEN bit to enable address detect.
6. Enable reception by setting the CREN bit.
2. Enable the asynchronous serial port by clearing
bit SYNC and setting bit SPEN.
3. If interrupts are desired, set enable bit RCIE.
4. If 9-bit reception is desired, set bit RX9.
5. Enable the reception by setting bit CREN.
7. The RCIF bit will be set when reception is
complete. The interrupt will be Acknowledged if
the RCIE and GIE bits are set.
6. Flag bit, RCIF, will be set when reception is
complete and an interrupt will be generated if
enable bit, RCIE, was set.
8. Read the RCSTA register to determine if any
error occurred during reception, as well as read
bit 9 of data (if applicable).
7. Read the RCSTA register to get the 9th bit (if
enabled) and determine if any error occurred
during reception.
9. Read RCREG to determine if the device is being
addressed.
10. If any error occurred, clear the CREN bit.
8. Read the 8-bit received data by reading the
RCREG register.
11. If the device has been addressed, clear the
ADDEN bit to allow all received data into the
receive buffer and interrupt the CPU.
9. If any error occurred, clear the error by clearing
enable bit CREN.
10. If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
FIGURE 18-6:
EUSART RECEIVE BLOCK DIAGRAM
CREN
OERR
FERR
x64 Baud Rate CLK
SPBRGH SPBRG
÷ 64
RSR Register
• • •
MSb
Stop
LSb
Start
BRG16
or
÷ 16
(8)
7
1
0
or
Baud Rate Generator
÷ 4
RX9
Pin Buffer
and Control
Data
Recovery
RX
RX9D
RCREG Register
FIFO
SPEN
8
Interrupt
RCIF
RCIE
Data Bus
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 213
PIC18F2420/2520/4420/4520
FIGURE 18-7:
ASYNCHRONOUS RECEPTION
Start
bit
Start
bit
Start
bit
RX (pin)
Stop
bit
Stop
bit
Stop
bit
bit 0 bit 1
bit 7/8
bit 0
bit 7/8
bit 7/8
Rcv Shift Reg
Rcv Buffer Reg
Word 2
RCREG
Word 1
RCREG
Read Rcv
Buffer Reg
RCREG
RCIF
(Interrupt Flag)
OERR bit
CREN
Note: This timing diagram shows three words appearing on the RX input. The RCREG (receive buffer) is read after the third word
causing the OERR (overrun) bit to be set.
TABLE 18-6: REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
Reset
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Values
on page
INTCON
PIR1
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
TXIF
RBIE
SSPIF
SSPIE
SSPIP
ADDEN
TMR0IF
INT0IF
RBIF
49
52
52
52
51
51
51
51
51
51
PSPIF(1)
PSPIE(1)
PSPIP(1)
SPEN
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
CCP1IF TMR2IF TMR1IF
CCP1IE TMR2IE TMR1IE
CCP1IP TMR2IP TMR1IP
PIE1
TXIE
IPR1
TXIP
RCSTA
RCREG
TXSTA
CREN
FERR
OERR
RX9D
EUSART Receive Register
CSRC
TX9
TXEN
—
SYNC
SCKP
SENDB
BRG16
BRGH
—
TRMT
WUE
TX9D
BAUDCON ABDOVF
RCIDL
ABDEN
SPBRGH
SPBRG
EUSART Baud Rate Generator Register, High Byte
EUSART Baud Rate Generator Register, Low Byte
Legend: — = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous reception.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
Following a wake-up event, the module generates an
RCIF interrupt. The interrupt is generated synchro-
nously to the Q clocks in normal operating modes
(Figure 18-8) and asynchronously, if the device is in
Sleep mode (Figure 18-9). The interrupt condition is
cleared by reading the RCREG register.
18.2.4
AUTO-WAKE-UP ON SYNC BREAK
CHARACTER
During Sleep mode, all clocks to the EUSART are
suspended. Because of this, the Baud Rate Generator
is inactive and a proper byte reception cannot be per-
formed. The auto-wake-up feature allows the controller
to wake-up due to activity on the RX/DT line while the
EUSART is operating in Asynchronous mode.
The WUE bit is automatically cleared once a low-to-
high transition is observed on the RX line following the
wake-up event. At this point, the EUSART module is in
Idle mode and returns to normal operation. This signals
to the user that the Sync Break event is over.
The auto-wake-up feature is enabled by setting the
WUE bit (BAUDCON<1>). Once set, the typical receive
sequence on RX/DT is disabled and the EUSART
remains in an Idle state, monitoring for a wake-up event
independent of the CPU mode. A wake-up event con-
sists of a high-to-low transition on the RX/DT line. (This
coincides with the start of a Sync Break or a Wake-up
Signal character for the LIN protocol.)
DS39631A-page 214
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
18.2.4.1
Special Considerations Using
Auto-Wake-up
18.2.4.2
Special Considerations Using
the WUE Bit
Since auto-wake-up functions by sensing rising edge
transitions on RX/DT, information with any state
changes before the Stop bit may signal a false end-of-
character and cause data or framing errors. To work
properly, therefore, the initial character in the transmis-
sion must be all ‘0’s. This can be 00h (8 bytes) for
standard RS-232 devices or 000h (12 bits) for LIN bus.
The timing of WUE and RCIF events may cause some
confusion when it comes to determining the validity of
received data. As noted, setting the WUE bit places the
EUSART in an Idle mode. The wake-up event causes a
receive interrupt by setting the RCIF bit. The WUE bit is
cleared after this when a rising edge is seen on RX/DT.
The interrupt condition is then cleared by reading the
RCREG register. Ordinarily, the data in RCREG will be
dummy data and should be discarded.
Oscillator start-up time must also be considered,
especially in applications using oscillators with longer
start-up intervals (i.e., XT or HS mode). The Sync
Break (or Wake-up Signal) character must be of
sufficient length and be followed by a sufficient interval
to allow enough time for the selected oscillator to start
and provide proper initialization of the EUSART.
The fact that the WUE bit has been cleared (or is still
set) and the RCIF flag is set should not be used as an
indicator of the integrity of the data in RCREG. Users
should consider implementing a parallel method in
firmware to verify received data integrity.
To assure that no actual data is lost, check the RCIDL
bit to verify that a receive operation is not in process. If
a receive operation is not occurring, the WUE bit may
then be set just prior to entering the Sleep mode.
FIGURE 18-8:
AUTO-WAKE-UP BIT (WUE) TIMINGS DURING NORMAL OPERATION
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Bit set by user
Auto-Cleared
OSC1
WUE bit(1)
RX/DT Line
RCIF
Cleared due to user read of RCREG
Note 1: The EUSART remains in Idle while the WUE bit is set.
FIGURE 18-9:
AUTO-WAKE-UP BIT (WUE) TIMINGS DURING SLEEP
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Bit set by user
Q1
Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Auto-Cleared
OSC1
WUE bit(2)
RX/DT Line
RCIF
Note 1
Cleared due to user read of RCREG
Sleep Ends
Sleep Command Executed
Note 1: If the wake-up event requires long oscillator warm-up time, the auto-clear of the WUE bit can occur before the oscillator is ready. This
sequence should not depend on the presence of Q clocks.
2: The EUSART remains in Idle while the WUE bit is set.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 215
PIC18F2420/2520/4420/4520
1. Configure the EUSART for the desired mode.
18.2.5
BREAK CHARACTER SEQUENCE
2. Set the TXEN and SENDB bits to set up the
Break character.
The EUSART module has the capability of sending the
special Break character sequences that are required by
the LIN bus standard. The Break character transmit
consists of a Start bit, followed by twelve ‘0’ bits and a
Stop bit. The frame Break character is sent whenever
the SENDB and TXEN bits (TXSTA<3> and
TXSTA<5>) are set while the Transmit Shift register is
loaded with data. Note that the value of data written to
TXREG will be ignored and all ‘0’s will be transmitted.
3. Load the TXREG with a dummy character to
initiate transmission (the value is ignored).
4. Write ‘55h’ to TXREG to load the Sync character
into the transmit FIFO buffer.
5. After the Break has been sent, the SENDB bit is
reset by hardware. The Sync character now
transmits in the preconfigured mode.
The SENDB bit is automatically reset by hardware after
the corresponding Stop bit is sent. This allows the user
to preload the transmit FIFO with the next transmit byte
following the Break character (typically, the Sync
character in the LIN specification).
When the TXREG becomes empty, as indicated by the
TXIF, the next data byte can be written to TXREG.
18.2.6
RECEIVING A BREAK CHARACTER
The enhanced USART module can receive a Break
character in two ways.
Note that the data value written to the TXREG for the
Break character is ignored. The write simply serves the
purpose of initiating the proper sequence.
The first method forces configuration of the baud rate
at a frequency of 9/13 the typical speed. This allows for
the Stop bit transition to be at the correct sampling loca-
tion (13 bits for Break versus Start bit and 8 data bits for
typical data).
The TRMT bit indicates when the transmit operation is
active or Idle, just as it does during normal transmis-
sion. See Figure 18-10 for the timing of the Break
character sequence.
The second method uses the auto-wake-up feature
described in Section 18.2.4 “Auto-Wake-up on Sync
Break Character”. By enabling this feature, the
EUSART will sample the next two transitions on RX/DT,
cause an RCIF interrupt and receive the next data byte
followed by another interrupt.
18.2.5.1
Break and Sync Transmit Sequence
The following sequence will send a message frame
header made up of a Break, followed by an Auto-Baud
Sync byte. This sequence is typical of a LIN bus
master.
Note that following a Break character, the user will
typically want to enable the Auto-Baud Rate Detect
feature. For both methods, the user can set the ABD bit
once the TXIF interrupt is observed.
FIGURE 18-10:
SEND BREAK CHARACTER SEQUENCE
Write to TXREG
Dummy Write
BRG Output
(Shift Clock)
TX (pin)
Start Bit
Bit 0
Bit 1
Break
Bit 11
Stop Bit
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
SENDB sampled here
Auto-Cleared
SENDB
(Transmit Shift
Reg. Empty Flag)
DS39631A-page 216
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
Once the TXREG register transfers the data to the TSR
register (occurs in one TCY), the TXREG is empty and
the TXIF flag bit (PIR1<4>) is set. The interrupt can be
18.3 EUSART Synchronous
Master Mode
The Synchronous Master mode is entered by setting
the CSRC bit (TXSTA<7>). In this mode, the data is
transmitted in a half-duplex manner (i.e., transmission
and reception do not occur at the same time). When
transmitting data, the reception is inhibited and vice
versa. Synchronous mode is entered by setting bit
SYNC (TXSTA<4>). In addition, enable bit SPEN
(RCSTA<7>) is set in order to configure the TX and RX
pins to CK (clock) and DT (data) lines, respectively.
enabled or disabled by setting or clearing the interrupt
enable bit, TXIE (PIE1<4>). TXIF is set regardless of
the state of enable bit TXIE; it cannot be cleared in
software. It will reset only when new data is loaded into
the TXREG register.
While flag bit TXIF indicates the status of the TXREG
register, another bit, TRMT (TXSTA<1>), shows the
status of the TSR register. TRMT is a read-only bit which
is set when the TSR is empty. No interrupt logic is tied to
this bit so the user has to poll this bit in order to deter-
mine if the TSR register is empty. The TSR is not
mapped in data memory so it is not available to the user.
The Master mode indicates that the processor trans-
mits the master clock on the CK line. Clock polarity is
selected with the SCKP bit (BAUDCON<4>); setting
SCKP sets the Idle state on CK as high, while clearing
the bit sets the Idle state as low. This option is provided
to support Microwire devices with this module.
To set up a Synchronous Master Transmission:
1. Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRG16
bit, as required, to achieve the desired baud rate.
18.3.1
EUSART SYNCHRONOUS MASTER
TRANSMISSION
2. Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC.
The EUSART transmitter block diagram is shown in
Figure 18-3. The heart of the transmitter is the Transmit
(Serial) Shift Register (TSR). The Shift register obtains
its data from the Read/Write Transmit Buffer register,
TXREG. The TXREG register is loaded with data in
software. The TSR register is not loaded until the last
bit has been transmitted from the previous load. As
soon as the last bit is transmitted, the TSR is loaded
with new data from the TXREG (if available).
3. If interrupts are desired, set enable bit TXIE.
4. If 9-bit transmission is desired, set bit TX9.
5. Enable the transmission by setting bit TXEN.
6. If 9-bit transmission is selected, the ninth bit
should be loaded in bit TX9D.
7. Start transmission by loading data to the TXREG
register.
8. If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
FIGURE 18-11:
SYNCHRONOUS TRANSMISSION
Q1 Q2 Q3Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1 Q2 Q3 Q4
Q3 Q4 Q1 Q2 Q3Q4 Q1Q2 Q3Q4 Q1 Q2Q3Q4 Q1 Q2Q3 Q4Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
RC7/RX/DT
bit 0
bit 1
bit 2
bit 7
bit 0
bit 1
bit 7
Word 2
Word 1
RC6/TX/CK pin
(SCKP = 0)
RC6/TX/CK pin
(SCKP = 1)
Write to
TXREG Reg
Write Word 1
Write Word 2
TXIF bit
(Interrupt Flag)
TRMT bit
‘1’
‘1’
TXEN bit
Note: Sync Master mode, SPBRG = 0, continuous transmission of two 8-bit words.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 217
PIC18F2420/2520/4420/4520
FIGURE 18-12:
SYNCHRONOUS TRANSMISSION (THROUGH TXEN)
RC7/RX/DT pin
bit 0
bit 2
bit 1
bit 6
bit 7
RC6/TX/CK pin
Write to
TXREG reg
TXIF bit
TRMT bit
TXEN bit
TABLE 18-7: REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER TRANSMISSION
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
PIR1
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
TXIF
RBIE
SSPIF
SSPIE
SSPIP
ADDEN
TMR0IF
INT0IF
RBIF
49
52
52
52
51
51
51
51
51
51
PSPIF(1)
PSPIE(1)
PSPIP(1)
SPEN
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
CCP1IF TMR2IF TMR1IF
CCP1IE TMR2IE TMR1IE
CCP1IP TMR2IP TMR1IP
PIE1
TXIE
IPR1
TXIP
RCSTA
TXREG
TXSTA
CREN
FERR
OERR
RX9D
EUSART Transmit Register
CSRC
TX9
TXEN
—
SYNC
SCKP
SENDB
BRG16
BRGH
—
TRMT
WUE
TX9D
BAUDCON ABDOVF
RCIDL
ABDEN
SPBRGH
SPBRG
EUSART Baud Rate Generator Register, High Byte
EUSART Baud Rate Generator Register, Low Byte
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master transmission.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
DS39631A-page 218
Preliminary
2004 Microchip Technology Inc.
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3. Ensure bits CREN and SREN are clear.
4. If interrupts are desired, set enable bit RCIE.
5. If 9-bit reception is desired, set bit RX9.
18.3.2
EUSART SYNCHRONOUS
MASTER RECEPTION
Once Synchronous mode is selected, reception is
enabled by setting either the Single Receive Enable bit,
SREN (RCSTA<5>), or the Continuous Receive
Enable bit, CREN (RCSTA<4>). Data is sampled on the
RX pin on the falling edge of the clock.
6. If a single reception is required, set bit SREN.
For continuous reception, set bit CREN.
7. Interrupt flag bit, RCIF, will be set when reception
is complete and an interrupt will be generated if
the enable bit, RCIE, was set.
If enable bit SREN is set, only a single word is received.
If enable bit CREN is set, the reception is continuous
until CREN is cleared. If both bits are set, then CREN
takes precedence.
8. Read the RCSTA register to get the 9th bit (if
enabled) and determine if any error occurred
during reception.
9. Read the 8-bit received data by reading the
RCREG register.
To set up a Synchronous Master Reception:
1. Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRG16
bit, as required, to achieve the desired baud rate.
10. If any error occurred, clear the error by clearing
bit CREN.
11. If using interrupts, ensure that the GIE and PEIE bits
in the INTCON register (INTCON<7:6>) are set.
2. Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC.
FIGURE 18-13:
SYNCHRONOUS RECEPTION (MASTER MODE, SREN)
Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
RC7/RX/DT
pin
bit 0
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 7
RC6/TX/CK pin
(SCKP = 0)
RC6/TX/CK pin
(SCKP = 1)
Write to
bit SREN
SREN bit
CREN bit
‘0’
‘0’
RCIF bit
(Interrupt)
Read
RXREG
Note: Timing diagram demonstrates Sync Master mode with bit SREN = 1and bit BRGH = 0.
TABLE 18-8: REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER RECEPTION
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
PIR1
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
TXIF
RBIE
SSPIF
SSPIE
SSPIP
ADDEN
TMR0IF
CCP1IF
CCP1IE
CCP1IP
FERR
INT0IF
RBIF
49
52
52
52
51
51
51
51
51
51
PSPIF(1)
PSPIE(1)
PSPIP(1)
SPEN
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
TMR2IF TMR1IF
TMR2IE TMR1IE
TMR2IP TMR1IP
PIE1
TXIE
IPR1
TXIP
RCSTA
RCREG
TXSTA
CREN
OERR
RX9D
EUSART Receive Register
CSRC
TX9
TXEN
—
SYNC
SCKP
SENDB
BRG16
BRGH
—
TRMT
WUE
TX9D
BAUDCON ABDOVF
RCIDL
ABDEN
SPBRGH EUSART Baud Rate Generator Register, High Byte
SPBRG EUSART Baud Rate Generator Register, Low Byte
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master reception.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 219
PIC18F2420/2520/4420/4520
To set up a Synchronous Slave Transmission:
18.4 EUSART Synchronous
Slave Mode
1. Enable the synchronous slave serial port by
setting bits SYNC and SPEN and clearing bit
CSRC.
Synchronous Slave mode is entered by clearing bit,
CSRC (TXSTA<7>). This mode differs from the
Synchronous Master mode in that the shift clock is sup-
plied externally at the CK pin (instead of being supplied
internally in Master mode). This allows the device to
transfer or receive data while in any low-power mode.
2. Clear bits CREN and SREN.
3. If interrupts are desired, set enable bit TXIE.
4. If 9-bit transmission is desired, set bit TX9.
5. Enable the transmission by setting enable bit
TXEN.
18.4.1
EUSART SYNCHRONOUS
SLAVE TRANSMISSION
6. If 9-bit transmission is selected, the ninth bit
should be loaded in bit TX9D.
The operation of the Synchronous Master and Slave
modes are identical, except in the case of the Sleep
mode.
7. Start transmission by loading data to the
TXREGx register.
8. If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
If two words are written to the TXREG and then the
SLEEPinstruction is executed, the following will occur:
a) The first word will immediately transfer to the
TSR register and transmit.
b) The second word will remain in the TXREG
register.
c) Flag bit, TXIF, will not be set.
d) When the first word has been shifted out of TSR,
the TXREG register will transfer the second
word to the TSR and flag bit, TXIF, will now be
set.
e) If enable bit TXIE is set, the interrupt will wake the
chip from Sleep. If the global interrupt is enabled,
the program will branch to the interrupt vector.
TABLE 18-9: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE TRANSMISSION
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
PIR1
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
TXIF
RBIE
SSPIF
SSPIE
SSPIP
ADDEN
TMR0IF
CCP1IF
INT0IF
RBIF
49
52
52
52
51
51
51
51
51
51
PSPIF(1)
PSPIE(1)
PSPIP(1)
SPEN
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
TMR2IF TMR1IF
PIE1
TXIE
CCP1IE TMR2IE TMR1IE
CCP1IP TMR2IP TMR1IP
IPR1
TXIP
RCSTA
TXREG
TXSTA
CREN
FERR
OERR
RX9D
EUSART Transmit Register
CSRC
TX9
TXEN
—
SYNC
SCKP
SENDB
BRG16
BRGH
—
TRMT
WUE
TX9D
BAUDCON ABDOVF
RCIDL
ABDEN
SPBRGH
SPBRG
EUSART Baud Rate Generator Register, High Byte
EUSART Baud Rate Generator Register, Low Byte
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave transmission.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
DS39631A-page 220
Preliminary
2004 Microchip Technology Inc.
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To set up a Synchronous Slave Reception:
18.4.2
EUSART SYNCHRONOUS SLAVE
RECEPTION
1. Enable the synchronous master serial port by
setting bits SYNC and SPEN and clearing bit
CSRC.
The operation of the Synchronous Master and Slave
modes is identical, except in the case of Sleep, or any
Idle mode and bit SREN, which is a “don’t care” in
Slave mode.
2. If interrupts are desired, set enable bit RCIE.
3. If 9-bit reception is desired, set bit RX9.
4. To enable reception, set enable bit CREN.
If receive is enabled by setting the CREN bit prior to
entering Sleep or any Idle mode, then a word may be
received while in this low-power mode. Once the word
is received, the RSR register will transfer the data to the
RCREG register; if the RCIE enable bit is set, the inter-
rupt generated will wake the chip from the low-power
mode. If the global interrupt is enabled, the program will
branch to the interrupt vector.
5. Flag bit, RCIF, will be set when reception is
complete. An interrupt will be generated if
enable bit, RCIE, was set.
6. Read the RCSTA register to get the 9th bit (if
enabled) and determine if any error occurred
during reception.
7. Read the 8-bit received data by reading the
RCREG register.
8. If any error occurred, clear the error by clearing
bit CREN.
9. If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
TABLE 18-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
PIR1
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
TXIF
RBIE
SSPIF
SSPIE
SSPIP
ADDEN
TMR0IF
CCP1IF
INT0IF
RBIF
49
52
52
52
51
51
51
51
51
51
PSPIF(1)
PSPIE(1)
PSPIP(1)
SPEN
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
TMR2IF TMR1IF
PIE1
TXIE
CCP1IE TMR2IE TMR1IE
CCP1IP TMR2IP TMR1IP
IPR1
TXIP
RCSTA
RCREG
TXSTA
CREN
FERR
OERR
RX9D
EUSART Receive Register
CSRC
TX9
TXEN
—
SYNC
SCKP
SENDB
BRG16
BRGH
—
TRMT
WUE
TX9D
BAUDCON ABDOVF
RCIDL
ABDEN
SPBRGH
SPBRG
EUSART Baud Rate Generator Register, High Byte
EUSART Baud Rate Generator Register, Low Byte
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave reception.
Note 1: Reserved in 28-pin devices; always maintain these bits clear.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 221
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 222
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
The ADCON0 register, shown in Register 19-1,
19.0 10-BIT ANALOG-TO-DIGITAL
controls the operation of the A/D module. The
ADCON1 register, shown in Register 19-2, configures
the functions of the port pins. The ADCON2 register,
shown in Register 19-3, configures the A/D clock
source, programmed acquisition time and justification.
CONVERTER (A/D) MODULE
The Analog-to-Digital (A/D) converter module has
10 inputs for the 28-pin devices and 13 for the 40/44-pin
devices. This module allows conversion of an analog
input signal to a corresponding 10-bit digital number.
The module has five registers:
• A/D Result High Register (ADRESH)
• A/D Result Low Register (ADRESL)
• A/D Control Register 0 (ADCON0)
• A/D Control Register 1 (ADCON1)
• A/D Control Register 2 (ADCON2)
REGISTER 19-1: ADCON0 REGISTER
U-0
—
U-0
—
R/W-0
CHS3
R/W-0
CHS2
R/W-0
CHS1
R/W-0
CHS0
R/W-0
R/W-0
ADON
GO/DONE
bit 7
bit 0
bit 7-6
bit 5-2
Unimplemented: Read as ‘0’
CHS3:CHS0: Analog Channel Select bits
0000= Channel 0 (AN0)
0001= Channel 1 (AN1)
0010= Channel 2 (AN2)
0011= Channel 3 (AN3)
0100= Channel 4 (AN4)
0101= Channel 5 (AN5)(1,2)
0110= Channel 6 (AN6)(1,2)
0111= Channel 7 (AN7)(1,2)
1000= Channel 8 (AN8)
1001= Channel 9 (AN9)
1010= Channel 10 (AN10)
1011= Channel 11 (AN11)
1100= Channel 12 (AN12
1101= Unimplemented(2)
1110= Unimplemented(2)
1111= Unimplemented(2)
Note 1: These channels are not implemented on 28-pin devices.
2: Performing a conversion on unimplemented channels will return a floating input
measurement.
bit 1
bit 0
GO/DONE: A/D Conversion Status bit
When ADON = 1:
1= A/D conversion in progress
0= A/D Idle
ADON: A/D On bit
1= A/D converter module is enabled
0= A/D converter module is disabled
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 223
PIC18F2420/2520/4420/4520
REGISTER 19-2: ADCON1 REGISTER
U-0
—
U-0
—
R/W-0
R/W-0
R/W-0(1)
PCFG3
R/W(1)
R/W(1)
R/W(1)
VCFG1
VCFG0
PCFG2
PCFG1
PCFG0
bit 7
bit 0
bit 7-6
bit 5
Unimplemented: Read as ‘0’
VCFG1: Voltage Reference Configuration bit (VREF- source)
1= VREF- (AN2)
0= VSS
bit 4
VCFG0: Voltage Reference Configuration bit (VREF+ source)
1= VREF+ (AN3)
0= VDD
bit 3-0
PCFG3:PCFG0: A/D Port Configuration Control bits:
PCFG3:
PCFG0
0000(1)
0001
0010
0011
0100
0101
0110
A
A
A
D
D
D
D
D
A
A
A
A
D
D
D
D
A
A
A
A
A
D
D
D
A
A
A
A
A
A
D
D
A
A
A
A
A
A
A
D
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
0111(1)
1000
1001
1010
1011
1100
1101
1110
1111
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
A
D
D
D
D
D
D
D
A
A
D
D
D
D
D
D
A
A
A
D
D
D
D
D
A
A
A
A
D
D
D
D
A
A
A
A
A
D
D
D
A
A
A
A
A
A
D
D
A
A
A
A
A
A
A
D
A = Analog input
D = Digital I/O
Note 1: The POR value of the PCFG bits depends on the value of the PBADEN con-
figuration bit. When PBADEN = 1, PCFG<3:0> = 0000; when PBADEN = 0,
PCFG<3:0> = 0111.
2: AN5 through AN7 are available only on 40/44-pin devices.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS39631A-page 224
Preliminary
2004 Microchip Technology Inc.
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REGISTER 19-3: ADCON2 REGISTER
R/W-0
ADFM
U-0
—
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
ACQT2
ACQT1
ACQT0
ADCS2
ADCS1
ADCS0
bit 7
bit 0
bit 7
ADFM: A/D Result Format Select bit
1= Right justified
0= Left justified
bit 6
Unimplemented: Read as ‘0’
bit 5-3
ACQT2:ACQT0: A/D Acquisition Time Select bits
111= 20 TAD
110= 16 TAD
101= 12 TAD
100= 8 TAD
011= 6 TAD
010= 4 TAD
001= 2 TAD
(1)
000= 0 TAD
bit 2-0
ADCS2:ADCS0: A/D Conversion Clock Select bits
111= FRC (clock derived from A/D RC oscillator)(1)
110= FOSC/64
101= FOSC/16
100= FOSC/4
011= FRC (clock derived from A/D RC oscillator)(1)
010= FOSC/32
001= FOSC/8
000= FOSC/2
Note 1: If the A/D FRC clock source is selected, a delay of one TCY (instruction cycle) is
added before the A/D clock starts. This allows the SLEEPinstruction to be executed
before starting a conversion.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 225
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The analog reference voltage is software selectable to
either the device’s positive and negative supply voltage
(VDD and VSS), or the voltage level on the RA3/AN3/
VREF+ and RA2/AN2/VREF-/CVREF pins.
A device Reset forces all registers to their Reset state.
This forces the A/D module to be turned off and any
conversion in progress is aborted.
Each port pin associated with the A/D converter can be
configured as an analog input, or as a digital I/O. The
ADRESH and ADRESL registers contain the result of
the A/D conversion. When the A/D conversion is com-
plete, the result is loaded into the ADRESH:ADRESL
register pair, the GO/DONE bit (ADCON0 register) is
cleared and A/D Interrupt Flag bit, ADIF, is set. The block
diagram of the A/D module is shown in Figure 19-1.
The A/D converter has a unique feature of being able
to operate while the device is in Sleep mode. To oper-
ate in Sleep, the A/D conversion clock must be derived
from the A/D’s internal RC oscillator.
The output of the sample and hold is the input into the
converter, which generates the result via successive
approximation.
FIGURE 19-1:
A/D BLOCK DIAGRAM
CHS3:CHS0
1100
AN12
1011
AN11
1010
AN10
1001
AN9
1000
AN8
0111
AN7(1)
0110
AN6(1)
0101
AN5(1)
0100
AN4
VAIN
0011
(Input Voltage)
10-Bit
Converter
A/D
AN3
0010
AN2
0001
VCFG1:VCFG0
AN1
0000
VDD
AN0
X0
X1
1X
VREF+
VREF-
Reference
Voltage
0X
VSS
Note 1: Channels AN5 through AN7 are not available on 28-pin devices.
2: I/O pins have diode protection to VDD and VSS.
DS39631A-page 226
Preliminary
2004 Microchip Technology Inc.
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The value in the ADRESH:ADRESL registers is not
5. Wait for A/D conversion to complete, by either:
• Polling for the GO/DONE bit to be cleared
modified for a Power-on Reset. The ADRESH:ADRESL
registers will contain unknown data after a Power-on
Reset.
OR
• Waiting for the A/D interrupt
After the A/D module has been configured as desired,
the selected channel must be acquired before the
conversion is started. The analog input channels must
have their corresponding TRIS bits selected as an
input. To determine acquisition time, see Section 19.1
“A/D Acquisition Requirements”. After this acquisi-
tion time has elapsed, the A/D conversion can be
started. An acquisition time can be programmed to
occur between setting the GO/DONE bit and the actual
start of the conversion.
6. Read A/D Result registers (ADRESH:ADRESL);
clear bit ADIF, if required.
7. For next conversion, go to step 1 or step 2, as
required. The A/D conversion time per bit is
defined as TAD. A minimum wait of 2 TAD is
required before the next acquisition starts.
FIGURE 19-2:
A/D TRANSFER FUNCTION
The following steps should be followed to perform an A/D
conversion:
3FFh
3FEh
1. Configure the A/D module:
• Configure analog pins, voltage reference and
digital I/O (ADCON1)
• Select A/D input channel (ADCON0)
• Select A/D acquisition time (ADCON2)
• Select A/D conversion clock (ADCON2)
• Turn on A/D module (ADCON0)
2. Configure A/D interrupt (if desired):
• Clear ADIF bit
003h
002h
001h
000h
• Set ADIE bit
• Set GIE bit
3. Wait the required acquisition time (if required).
4. Start conversion:
Analog Input Voltage
• Set GO/DONE bit (ADCON0 register)
FIGURE 19-3:
ANALOG INPUT MODEL
VDD
Sampling
Switch
VT = 0.6V
ANx
SS
RIC ≤ 1k
RSS
Rs
CPIN
VAIN
ILEAKAGE
± 100 nA
CHOLD = 25 pF
VT = 0.6V
5 pF
VSS
Legend: CPIN
= input capacitance
= threshold voltage
VT
6 V
5 V
4 V
3 V
2 V
ILEAKAGE = leakage current at the pin due to
various junctions
VDD
RIC
= interconnect resistance
= sampling switch
SS
CHOLD
RSS
= sample/hold capacitance (from DAC)
= sampling switch resistance
1
2
3
4
(kΩ)
Sampling Switch
2004 Microchip Technology Inc.
Preliminary
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To calculate the minimum acquisition time,
19.1 A/D Acquisition Requirements
Equation 19-1 may be used. This equation assumes
that 1/2 LSb error is used (1024 steps for the A/D). The
1/2 LSb error is the maximum error allowed for the A/D
to meet its specified resolution.
For the A/D converter to meet its specified accuracy,
the charge holding capacitor (CHOLD) must be allowed
to fully charge to the input channel voltage level. The
analog input model is shown in Figure 19-3. The
source impedance (RS) and the internal sampling
switch (RSS) impedance directly affect the time
required to charge the capacitor CHOLD. The sampling
switch (RSS) impedance varies over the device voltage
(VDD). The source impedance affects the offset voltage
at the analog input (due to pin leakage current). The
maximum recommended impedance for analog
sources is 2.5 kΩ. After the analog input channel is
selected (changed), the channel must be sampled for
at least the minimum acquisition time before starting a
conversion.
Example 19-3 shows the calculation of the minimum
required acquisition time TACQ. This calculation is
based on the following application system
assumptions:
CHOLD
Rs
Conversion Error
VDD
Temperature
=
=
≤
=
=
25 pF
2.5 kΩ
1/2 LSb
5V → Rss = 2 kΩ
85°C (system max.)
Note:
When the conversion is started, the
holding capacitor is disconnected from the
input pin.
EQUATION 19-1: ACQUISITION TIME
TACQ
=
=
Amplifier Settling Time + Holding Capacitor Charging Time + Temperature Coefficient
TAMP + TC + TCOFF
EQUATION 19-2: A/D MINIMUM CHARGING TIME
VHOLD
or
TC
=
=
(VREF – (VREF/2048)) • (1 – e(-TC/CHOLD(RIC + RSS + RS))
)
-(CHOLD)(RIC + RSS + RS) ln(1/2048)
EQUATION 19-3: CALCULATING THE MINIMUM REQUIRED ACQUISITION TIME
TACQ
TAMP
TCOFF
=
=
=
TAMP + TC + TCOFF
0.2 µs
(Temp – 25°C)(0.02 µs/°C)
(85°C – 25°C)(0.02 µs/°C)
1.2 µs
Temperature coefficient is only required for temperatures > 25°C. Below 25°C, TCOFF = 0 ms.
TC
=
-(CHOLD)(RIC + RSS + RS) ln(1/2047) µs
-(25 pF) (1 kΩ + 2 kΩ + 2.5 kΩ) ln(0.0004883) µs
1.05 µs
TACQ
=
0.2 µs + 1 µs + 1.2 µs
2.4 µs
DS39631A-page 228
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
19.2 Selecting and Configuring
Acquisition Time
19.3 Selecting the A/D Conversion
Clock
The ADCON2 register allows the user to select an
acquisition time that occurs each time the GO/DONE
bit is set. It also gives users the option to use an
automatically determined acquisition time.
The A/D conversion time per bit is defined as TAD. The
A/D conversion requires 11 TAD per 10-bit conversion.
The source of the A/D conversion clock is software
selectable. There are seven possible options for TAD:
Acquisition time may be set with the ACQT2:ACQT0
bits (ADCON2<5:3>), which provides a range of 2 to
20 TAD. When the GO/DONE bit is set, the A/D module
continues to sample the input for the selected acquisi-
tion time, then automatically begins a conversion.
Since the acquisition time is programmed, there may
be no need to wait for an acquisition time between
selecting a channel and setting the GO/DONE bit.
• 2 TOSC
• 4 TOSC
• 8 TOSC
• 16 TOSC
• 32 TOSC
• 64 TOSC
• Internal RC Oscillator
Manual
acquisition
is
selected
when
For correct A/D conversions, the A/D conversion clock
(TAD) must be as short as possible, but greater than the
minimum TAD (see parameter 130 for more
information).
ACQT2:ACQT0 = 000. When the GO/DONE bit is set,
sampling is stopped and a conversion begins. The user
is responsible for ensuring the required acquisition time
has passed between selecting the desired input
channel and setting the GO/DONE bit. This option is
also the default Reset state of the ACQT2:ACQT0 bits
and is compatible with devices that do not offer
programmable acquisition times.
Table 19-1 shows the resultant TAD times derived from
the device operating frequencies and the A/D clock
source selected.
In either case, when the conversion is completed, the
GO/DONE bit is cleared, the ADIF flag is set and the
A/D begins sampling the currently selected channel
again. If an acquisition time is programmed, there is
nothing to indicate if the acquisition time has ended or
if the conversion has begun.
TABLE 19-1: TAD vs. DEVICE OPERATING FREQUENCIES
AD Clock Source (TAD)
Maximum Device Frequency
Operation
ADCS2:ADCS0
PIC18F2X20/4X20
PIC18LF2X20/4X20(4)
2 TOSC
4 TOSC
8 TOSC
16 TOSC
32 TOSC
64 TOSC
RC(3)
000
100
001
101
010
110
x11
2.86 MHz
5.71 MHz
11.43 MHz
22.86 MHz
40.0 MHz
40.0 MHz
1.00 MHz(1)
1.43 kHz
2.86 MHz
5.72 MHz
11.43 MHz
22.86 MHz
22.86 MHz
1.00 MHz(2)
Note 1: The RC source has a typical TAD time of 1.2 µs.
2: The RC source has a typical TAD time of 2.5 µs.
3: For device frequencies above 1 MHz, the device must be in Sleep for the entire conversion or the A/D
accuracy may be out of specification.
4: Low-power (PIC18LFXXXX) devices only.
2004 Microchip Technology Inc.
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19.4 Operation in Power Managed
Modes
19.5 Configuring Analog Port Pins
The ADCON1, TRISA, TRISB and TRISE registers all
configure the A/D port pins. The port pins needed as
analog inputs must have their corresponding TRIS bits
set (input). If the TRIS bit is cleared (output), the digital
output level (VOH or VOL) will be converted.
The selection of the automatic acquisition time and A/D
conversion clock is determined in part by the clock
source and frequency while in a power managed mode.
If the A/D is expected to operate while the device is in
a power managed mode, the ACQT2:ACQT0 and
ADCS2:ADCS0 bits in ADCON2 should be updated in
accordance with the clock source to be used in that
mode. After entering the mode, an A/D acquisition or
conversion may be started. Once started, the device
should continue to be clocked by the same clock
source until the conversion has been completed.
The A/D operation is independent of the state of the
CHS3:CHS0 bits and the TRIS bits.
Note 1: When reading the Port register, all pins
configured as analog input channels will
read as cleared (a low level). Pins con-
figured as digital inputs will convert as
analog inputs. Analog levels on a digitally
configured input will be accurately
converted.
If desired, the device may be placed into the
corresponding Idle mode during the conversion. If the
device clock frequency is less than 1 MHz, the A/D RC
clock source should be selected.
2: Analog levels on any pin defined as a dig-
ital input may cause the digital input buffer
to consume current out of the device’s
specification limits.
Operation in the Sleep mode requires the A/D FRC
clock to be selected. If bits ACQT2:ACQT0 are set to
‘000’ and a conversion is started, the conversion will be
delayed one instruction cycle to allow execution of the
SLEEPinstruction and entry to Sleep mode. The IDLEN
bit (OSCCON<7>) must have already been cleared
prior to starting the conversion.
3: The PBADEN bit in Configuration
Register 3H configures PORTB pins to
reset as analog or digital pins by control-
ling how the PCFG0 bits in ADCON1 are
reset.
DS39631A-page 230
Preliminary
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After the A/D conversion is completed or aborted, a
2 TAD wait is required before the next acquisition can
be started. After this wait, acquisition on the selected
channel is automatically started.
19.6 A/D Conversions
Figure 19-4 shows the operation of the A/D converter
after the GO bit has been set and the ACQT2:ACQT0
bits are cleared. A conversion is started after the follow-
ing instruction to allow entry into Sleep mode before the
conversion begins.
Note:
The GO/DONE bit should NOT be set in
the same instruction that turns on the A/D.
Figure 19-5 shows the operation of the A/D converter
after the GO bit has been set and the ACQT2:ACQT0
bits are set to ‘010’ and selecting a 4 TAD acquisition
time before the conversion starts.
19.7 Discharge
The discharge phase is used to initialize the value of
the capacitor array. The array is discharged before
every sample. This feature helps to optimize the unity-
gain amplifier, as the circuit always needs to charge the
capacitor array, rather than charge/discharge based on
previous measure values.
Clearing the GO/DONE bit during a conversion will abort
the current conversion. The A/D Result register pair will
NOT be updated with the partially completed A/D
conversion sample. This means the ADRESH:ADRESL
registers will continue to contain the value of the last
completed conversion (or the last value written to the
ADRESH:ADRESL registers).
FIGURE 19-4:
A/D CONVERSION TAD CYCLES (ACQT<2:0> = 000, TACQ = 0)
TCY - TAD
TAD6 TAD7 TAD8 TAD9 TAD10 TAD11 TAD1
TAD1 TAD2 TAD3 TAD4 TAD5
b7
b6
b4
b1
b0
b9
b8
b5
b3
b2
Conversion starts
Discharge
Holding capacitor is disconnected from analog input (typically 100 ns)
Set GO bit
On the following cycle:
ADRESH:ADRESL is loaded, GO bit is cleared,
ADIF bit is set, holding capacitor is connected to analog input.
FIGURE 19-5:
A/D CONVERSION TAD CYCLES (ACQT<2:0> = 010, TACQ = 4 TAD)
TAD Cycles
TACQT Cycles
7
8
9
10
b1
11 TAD1
b0
1
2
3
4
1
2
3
4
5
6
b7
b6
b3
b2
b8
b5
b4
b9
Automatic
Acquisition
Time
Discharge
Conversion starts
(Holding capacitor is disconnected)
Set GO bit
(Holding capacitor continues
acquiring input)
On the following cycle:
ADRESH:ADRESL is loaded, GO bit is cleared,
ADIF bit is set, holding capacitor is connected to analog input.
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desired location). The appropriate analog input chan-
19.8 Use of the CCP2 Trigger
nel must be selected and the minimum acquisition
period is either timed by the user, or an appropriate
TACQ time selected before the Special Event Trigger
sets the GO/DONE bit (starts a conversion).
An A/D conversion can be started by the Special Event
Trigger of the CCP2 module. This requires that the
CCP2M3:CCP2M0
bits
(CCP2CON<3:0>)
be
programmed as ‘1011’ and that the A/D module is
enabled (ADON bit is set). When the trigger occurs, the
GO/DONE bit will be set, starting the A/D acquisition
and conversion and the Timer1 (or Timer3) counter will
be reset to zero. Timer1 (or Timer3) is reset to automat-
ically repeat the A/D acquisition period with minimal
software overhead (moving ADRESH:ADRESL to the
If the A/D module is not enabled (ADON is cleared), the
Special Event Trigger will be ignored by the A/D
module, but will still reset the Timer1 (or Timer3)
counter.
TABLE 19-2: REGISTERS ASSOCIATED WITH A/D OPERATION
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
PIR1
PIE1
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
TXIF
TXIE
TXIP
EEIF
EEIE
EEIP
RBIE
SSPIF
SSPIE
SSPIP
BCLIF
BCLIE
BCLIP
TMR0IF
CCP1IF
CCP1IE
CCP1IP
HLVDIF
HLVDIE
HLVDIP
INT0IF
TMR2IF
TMR2IE
TMR2IP
TMR3IF
TMR3IE
TMR3IP
RBIF
49
52
52
52
52
52
52
51
51
51
51
51
52
52
52
52
52
52
52
52
PSPIF(1)
PSPIE(1)
PSPIP(1)
OSCFIF
OSCFIE
OSCFIP
ADIF
ADIE
ADIP
CMIF
CMIE
CMIP
RCIF
RCIE
RCIP
—
TMR1IF
TMR1IE
TMR1IP
CCP2IF
CCP2IE
CCP2IP
IPR1
PIR2
PIE2
—
IPR2
—
ADRESH A/D Result Register, High Byte
ADRESL A/D Result Register, Low Byte
ADCON0
ADCON1
ADCON2
PORTA
TRISA
—
—
—
CHS3
VCFG1
ACQT2
RA5
CHS2
VCFG0
ACQT1
RA4
CHS1
PCFG3
ACQT0
RA3
CHS0 GO/DONE ADON
—
PCFG2
ADCS2
RA2
PCFG1
ADCS1
RA1
PCFG0
ADCS0
RA0
ADFM
RA7(1)
—
RA6(1)
TRISA7(2) TRISA6(2) PORTA Data Direction Control Register
PORTB
TRISB
RB7
PORTB Data Direction Control Register
PORTB Data Latch Register (Read and Write to Data Latch)
RB6
RB5
RB4
RB3
RB2
RB1
RB0
LATB
PORTE(4)
TRISE(4)
LATE(4)
—
IBF
—
—
OBF
—
—
IBOV
—
—
PSPMODE
—
RE3(3)
RE2
RE1
RE0
—
TRISE2
TRISE1
TRISE0
—
PORTE Data Latch Register
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for A/D conversion.
Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear.
2: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary
oscillator modes. When disabled, these bits read as ‘0’.
3: RE3 port bit is available only as an input pin when the MCLRE configuration bit is ‘0’.
4: These registers are not implemented on 28-pin devices.
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The CMCON register (Register 20-1) selects the
comparator input and output configuration. Block
diagrams of the various comparator configurations are
shown in Figure 20-1.
20.0 COMPARATOR MODULE
The analog comparator module contains two
comparators that can be configured in a variety of
ways. The inputs can be selected from the analog
inputs multiplexed with pins RA0 through RA5, as well
as the on-chip voltage reference (see Section 21.0
“Comparator Voltage Reference Module”). The digi-
tal outputs (normal or inverted) are available at the pin
level and can also be read through the control register.
REGISTER 20-1: CMCON REGISTER
R-0
R-0
R/W-0
C2INV
R/W-0
C1INV
R/W-0
CIS
R/W-1
CM2
R/W-1
CM1
R/W-1
CM0
C2OUT
C1OUT
bit 7
bit 0
bit 7
C2OUT: Comparator 2 Output bit
When C2INV = 0:
1= C2 VIN+ > C2 VIN-
0= C2 VIN+ < C2 VIN-
When C2INV = 1:
1= C2 VIN+ < C2 VIN-
0= C2 VIN+ > C2 VIN-
bit 6
C1OUT: Comparator 1 Output bit
When C1INV = 0:
1= C1 VIN+ > C1 VIN-
0= C1 VIN+ < C1 VIN-
When C1INV = 1:
1= C1 VIN+ < C1 VIN-
0= C1 VIN+ > C1 VIN-
bit 5
bit 4
bit 3
C2INV: Comparator 2 Output Inversion bit
1= C2 output inverted
0= C2 output not inverted
C1INV: Comparator 1 Output Inversion bit
1= C1 output inverted
0= C1 output not inverted
CIS: Comparator Input Switch bit
When CM2:CM0 = 110:
1= C1 VIN- connects to RA3/AN3/VREF+
C2 VIN- connects to RA2/AN2/VREF-/CVREF
0= C1 VIN- connects to RA0/AN0
C2 VIN- connects to RA1/AN1
bit 2-0
CM2:CM0: Comparator Mode bits
Figure 20-1 shows the Comparator modes and the CM2:CM0 bit settings.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
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changed, the comparator output level may not be valid
for the specified mode change delay shown in
20.1 Comparator Configuration
There are eight modes of operation for the compara-
tors, shown in Figure 20-1. Bits CM2:CM0 of the
CMCON register are used to select these modes. The
TRISA register controls the data direction of the com-
parator pins for each mode. If the Comparator mode is
Section 26.0 “Electrical Characteristics”.
Note:
Comparator interrupts should be disabled
during Comparator mode change;
otherwise, a false interrupt may occur.
a
FIGURE 20-1:
COMPARATOR I/O OPERATING MODES
Comparators Reset
Comparators Off (POR Default Value)
CM2:CM0 = 000
CM2:CM0 = 111
A
D
VIN-
VIN-
RA0/AN0
RA0/AN0
Off (Read as ‘0’)
Off (Read as ‘0’)
Off (Read as ‘0’)
Off (Read as ‘0’)
C1
C2
C1
C2
VIN+
VIN+
A
D
RA3/AN3/
VREF+
RA3/AN3/
VREF+
A
D
D
VIN-
VIN-
RA1/AN1
RA1/AN1
VIN+
VIN+
A
RA2/AN2/
VREF-/CVREF
RA2/AN2/
VREF-/CVREF
Two Independent Comparators
Two Independent Comparators with Outputs
CM2:CM0 = 010
CM2:CM0 = 011
A
A
VIN-
VIN-
RA0/AN0
RA0/AN0
C1OUT
C2OUT
C1OUT
C2OUT
C1
C2
C1
C2
VIN+
RA3/AN3/
VREF+
VIN+
A
A
RA3/AN3/
VREF+
RA4/T0CKI/C1OUT*
A
A
VIN-
RA1/AN1
RA2/AN2/
A
A
VIN-
RA1/AN1
VIN+
RA2/AN2/
VREF-/CVREF
VIN+
VREF-/CVREF
RA5/AN4/SS/HLVDIN/C2OUT*
Two Common Reference Comparators
Two Common Reference Comparators with Outputs
CM2:CM0 = 100
CM2:CM0 = 101
A
A
VIN-
VIN-
RA0/AN0
RA0/AN0
C1OUT
C2OUT
C1OUT
C1
C2
C1
VIN+
VIN+
A
A
RA3/AN3/
VREF+
RA3/AN3/
VREF+
RA4/T0CKI/C1OUT*
A
D
VIN-
RA1/AN1
RA2/AN2/
A
VIN-
RA1/AN1
VIN+
C2OUT
RA2/AN2/
D
C2
VIN+
VREF-/CVREF
VREF-/CVREF
RA5/AN4/SS/HLVDIN/C2OUT*
Four Inputs Multiplexed to Two Comparators
One Independent Comparator with Output
CM2:CM0 = 110
CM2:CM0 = 001
A
A
A
VIN-
RA0/AN0
RA0/AN0
CIS = 0
CIS = 1
VIN-
A
C1OUT
C1
RA3/AN3/
VREF+
VIN+
RA3/AN3/
VREF+
C1OUT
C2OUT
C1
C2
VIN+
A
A
RA4/T0CKI/C1OUT*
RA1/AN1
VIN-
CIS = 0
CIS = 1
RA2/AN2/
VREF-/CVREF
VIN+
D
D
VIN-
RA1/AN1
RA2/AN2/
Off (Read as ‘0’)
C2
VIN+
CVREF
From VREF Module
VREF-/CVREF
A = Analog Input, port reads zeros always
D = Digital Input
CIS (CMCON<3>) is the Comparator Input Switch
* Setting the TRISA<5:4> bits will disable the comparator outputs by configuring the pins as inputs.
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20.3.2
INTERNAL REFERENCE SIGNAL
20.2 Comparator Operation
The comparator module also allows the selection of an
internally generated voltage reference from the
comparator voltage reference module. This module is
described in more detail in Section 21.0 “Comparator
Voltage Reference Module”.
A single comparator is shown in Figure 20-2, along with
the relationship between the analog input levels and
the digital output. When the analog input at VIN+ is less
than the analog input VIN-, the output of the comparator
is a digital low level. When the analog input at VIN+ is
greater than the analog input VIN-, the output of the
comparator is a digital high level. The shaded areas of
the output of the comparator in Figure 20-2 represent
the uncertainty, due to input offsets and response time.
The internal reference is only available in the mode
where four inputs are multiplexed to two comparators
(CM2:CM0 = 110). In this mode, the internal voltage
reference is applied to the VIN+ pin of both
comparators.
20.3 Comparator Reference
20.4 Comparator Response Time
Depending on the comparator operating mode, either
an external or internal voltage reference may be used.
The analog signal present at VIN- is compared to the
signal at VIN+ and the digital output of the comparator
is adjusted accordingly (Figure 20-2).
Response time is the minimum time, after selecting a
new reference voltage or input source, before the
comparator output has a valid level. If the internal ref-
erence is changed, the maximum delay of the internal
voltage reference must be considered when using the
comparator outputs. Otherwise, the maximum delay of
the comparators should be used (see Section 26.0
“Electrical Characteristics”).
FIGURE 20-2:
SINGLE COMPARATOR
VIN+
VIN-
+
20.5 Comparator Outputs
Output
–
The comparator outputs are read through the CMCON
register. These bits are read-only. The comparator
outputs may also be directly output to the RA4 and RA5
I/O pins. When enabled, multiplexors in the output path
of the RA4 and RA5 pins will switch and the output of
each pin will be the unsynchronized output of the
comparator. The uncertainty of each of the
comparators is related to the input offset voltage and
the response time given in the specifications.
Figure 20-3 shows the comparator output block
diagram.
VIN-
VIN+
Output
The TRISA bits will still function as an output enable/
disable for the RA4 and RA5 pins while in this mode.
The polarity of the comparator outputs can be changed
using the C2INV and C1INV bits (CMCON<4:5>).
20.3.1
EXTERNAL REFERENCE SIGNAL
Note 1: When reading the Port register, all pins
configured as analog inputs will read as a
‘0’. Pins configured as digital inputs will
convert an analog input according to the
Schmitt Trigger input specification.
When external voltage references are used, the
comparator module can be configured to have the com-
parators operate from the same or different reference
sources. However, threshold detector applications may
require the same reference. The reference signal must
be between VSS and VDD and can be applied to either
pin of the comparator(s).
2: Analog levels on any pin defined as a
digital input may cause the input buffer to
consume more current than is specified.
2004 Microchip Technology Inc.
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FIGURE 20-3:
COMPARATOR OUTPUT BLOCK DIAGRAM
Port pins
To RA4 or
RA5 pin
D
Q
Bus
Data
CxINV
EN
Read CMCON
D
Q
Set
CMIF
bit
EN
CL
From
other
Comparator
Reset
20.6 Comparator Interrupts
20.7 Comparator Operation
During Sleep
The comparator interrupt flag is set whenever there is
a change in the output value of either comparator.
Software will need to maintain information about the
status of the output bits, as read from CMCON<7:6>, to
determine the actual change that occurred. The CMIF
bit (PIR2<6>) is the Comparator Interrupt Flag. The
CMIF bit must be reset by clearing it. Since it is also
possible to write a ‘1’ to this register, a simulated
interrupt may be initiated.
When a comparator is active and the device is placed
in Sleep mode, the comparator remains active and the
interrupt is functional if enabled. This interrupt will
wake-up the device from Sleep mode, when enabled.
Each operational comparator will consume additional
current, as shown in the comparator specifications. To
minimize power consumption while in Sleep mode, turn
off the comparators (CM2:CM0 = 111) before entering
Sleep. If the device wakes up from Sleep, the contents
of the CMCON register are not affected.
Both the CMIE bit (PIE2<6>) and the PEIE bit
(INTCON<6>) must be set to enable the interrupt. In
addition, the GIE bit (INTCON<7>) must also be set. If
any of these bits are clear, the interrupt is not enabled,
though the CMIF bit will still be set if an interrupt
condition occurs.
20.8 Effects of a Reset
A device Reset forces the CMCON register to its Reset
state, causing the comparator modules to be turned off
(CM2:CM0 = 111). However, the input pins (RA0
through RA3) are configured as analog inputs by
default on device Reset. The I/O configuration for these
pins is determined by the setting of the PCFG3:PCFG0
bits (ADCON1<3:0>). Therefore, device current is
minimized when analog inputs are present at Reset
time.
Note:
If a change in the CMCON register
(C1OUT or C2OUT) should occur when a
read operation is being executed (start of
the Q2 cycle), then the CMIF (PIR
registers) interrupt flag may not get set.
The user, in the Interrupt Service Routine, can clear the
interrupt in the following manner:
a) Any read or write of CMCON will end the
mismatch condition.
b) Clear flag bit CMIF.
A mismatch condition will continue to set flag bit CMIF.
Reading CMCON will end the mismatch condition and
allow flag bit CMIF to be cleared.
DS39631A-page 236
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range by more than 0.6V in either direction, one of the
diodes is forward biased and a latch-up condition may
occur. A maximum source impedance of 10 kΩ is
recommended for the analog sources. Any external
component connected to an analog input pin, such as
a capacitor or a Zener diode, should have very little
leakage current.
20.9 Analog Input Connection
Considerations
A simplified circuit for an analog input is shown in
Figure 20-4. Since the analog pins are connected to a
digital output, they have reverse biased diodes to VDD
and VSS. The analog input, therefore, must be between
VSS and VDD. If the input voltage deviates from this
FIGURE 20-4:
COMPARATOR ANALOG INPUT MODEL
VDD
VT = 0.6V
RIC
RS < 10k
AIN
Comparator
Input
ILEAKAGE
±500 nA
CPIN
5 pF
VA
VT = 0.6V
VSS
Legend: CPIN
=
=
Input Capacitance
Threshold Voltage
VT
ILEAKAGE = Leakage Current at the pin due to various junctions
RIC
RS
VA
=
=
=
Interconnect Resistance
Source Impedance
Analog Voltage
TABLE 20-1: REGISTERS ASSOCIATED WITH COMPARATOR MODULE
Reset
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Values
on page
CMCON
CVRCON
INTCON
PIR2
C2OUT
CVREN
C1OUT
CVROE
C2INV
CVRR
C1INV
CVRSS
INT0IE
EEIF
CIS
CM2
CM1
CVR1
INT0IF
CM0
CVR0
RBIF
51
51
52
52
52
52
52
52
52
CVR3
RBIE
BCLIF
BCLIE
BCLIP
RA3
CVR2
GIE/GIEH PEIE/GIEL TMR0IE
TMR0IF
HLVDIF
OSCFIF
OSCFIE
OSCFIP
RA7(1)
CMIF
CMIE
CMIP
RA6(1)
—
—
TMR3IF CCP2IF
PIE2
EEIE
HLVDIE TMR3IE CCP2IE
HLVDIP TMR3IP CCP2IP
IPR2
—
EEIP
PORTA
LATA
RA5
RA4
RA2
RA1
RA0
LATA7(1)
LATA6(1) PORTA Data Latch Register (Read and Write to Data Latch)
TRISA
TRISA7(1) TRISA6(1) PORTA Data Direction Control Register
Legend: — = unimplemented, read as ‘0’. Shaded cells are unused by the comparator module.
Note 1: PORTA<7:6> and their direction and latch bits are individually configured as port pins based on various
primary oscillator modes. When disabled, these bits read as ‘0’.
2004 Microchip Technology Inc.
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NOTES:
DS39631A-page 238
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2004 Microchip Technology Inc.
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is selected by the CVRR bit (CVRCON<5>). The pri-
mary difference between the ranges is the size of the
steps selected by the CVREF Selection bits
21.0 COMPARATOR VOLTAGE
REFERENCE MODULE
(CVR3:CVR0), with one range offering finer resolution.
The equations used to calculate the output of the
comparator voltage reference are as follows:
The comparator voltage reference is a 16-tap resistor
ladder network that provides a selectable reference
voltage. Although its primary purpose is to provide a
reference for the analog comparators, it may also be
used independently of them.
If CVRR = 1:
CVREF = ((CVR3:CVR0)/24) x CVRSRC
A block diagram of the module is shown in Figure 21-1.
The resistor ladder is segmented to provide two ranges
of CVREF values and has a power-down function to
conserve power when the reference is not being used.
The module’s supply reference can be provided from
either device VDD/VSS or an external voltage reference.
If CVRR = 0:
CVREF = (CVRSRC x 1/4) + (((CVR3:CVR0)/32) x
CVRSRC)
The comparator reference supply voltage can come
from either VDD and VSS, or the external VREF+ and
VREF- that are multiplexed with RA2 and RA3. The
voltage source is selected by the CVRSS bit
(CVRCON<4>).
21.1 Configuring the Comparator
Voltage Reference
The settling time of the comparator voltage reference
must be considered when changing the CVREF out-
put (see Table 26-3 in Section 26.0 “Electrical
Characteristics”).
The voltage reference module is controlled through the
CVRCON register (Register 21-1). The comparator
voltage reference provides two ranges of output volt-
age, each with 16 distinct levels. The range to be used
REGISTER 21-1: CVRCON REGISTER
R/W-0
CVREN CVROE(1)
bit 7
R/W-0
R/W-0
CVRR
R/W-0
R/W-0
CVR3
R/W-0
CVR2
R/W-0
CVR1
R/W-0
CVR0
CVRSS
bit 0
bit 7
bit 6
CVREN: Comparator Voltage Reference Enable bit
1= CVREF circuit powered on
0= CVREF circuit powered down
CVROE: Comparator VREF Output Enable bit(1)
1= CVREF voltage level is also output on the RA2/AN2/VREF-/CVREF pin
0= CVREF voltage is disconnected from the RA2/AN2/VREF-/CVREF pin
Note 1: CVROE overrides the TRISA<2> bit setting.
bit 5
CVRR: Comparator VREF Range Selection bit
1= 0 to 0.667 CVRSRC, with CVRSRC/24 step size (low range)
0= 0.25 CVRSRC to 0.75 CVRSRC, with CVRSRC/32 step size (high range)
bit 4
CVRSS: Comparator VREF Source Selection bit
1= Comparator reference source, CVRSRC = (VREF+) – (VREF-)
0= Comparator reference source, CVRSRC = VDD – VSS
bit 3-0
CVR3:CVR0: Comparator VREF Value Selection bits (0 ≤ (CVR3:CVR0) ≤ 15)
When CVRR = 1:
CVREF = ((CVR3:CVR0)/24) • (CVRSRC)
When CVRR = 0:
CVREF = (CVRSRC/4) + ((CVR3:CVR0)/32) • (CVRSRC)
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
Preliminary
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FIGURE 21-1:
VOLTAGE REFERENCE BLOCK DIAGRAM
CVRSS = 1
VREF+
VDD
8R
CVRSS = 0
CVR3:CVR0
R
CVREN
R
R
R
16 Steps
CVREF
R
R
R
CVRR
VREF-
8R
CVRSS = 1
CVRSS = 0
21.2 Voltage Reference Accuracy/Error
21.4 Effects of a Reset
The full range of voltage reference cannot be realized
due to the construction of the module. The transistors
on the top and bottom of the resistor ladder network
(Figure 21-1) keep CVREF from approaching the refer-
ence source rails. The voltage reference is derived
from the reference source; therefore, the CVREF output
changes with fluctuations in that source. The tested
absolute accuracy of the voltage reference can be
found in Section 26.0 “Electrical Characteristics”.
A device Reset disables the voltage reference by
clearing bit, CVREN (CVRCON<7>). This Reset also
disconnects the reference from the RA2 pin by clearing
bit, CVROE (CVRCON<6>) and selects the high-voltage
range by clearing bit, CVRR (CVRCON<5>). The CVR
value select bits are also cleared.
21.5 Connection Considerations
The voltage reference module operates independently
of the comparator module. The output of the reference
generator may be connected to the RA2 pin if the
CVROE bit is set. Enabling the voltage reference out-
put onto RA2 when it is configured as a digital input will
increase current consumption. Connecting RA2 as a
digital output with CVRSS enabled will also increase
current consumption.
21.3 Operation During Sleep
When the device wakes up from Sleep through an
interrupt or a Watchdog Timer time-out, the contents of
the CVRCON register are not affected. To minimize
current consumption in Sleep mode, the voltage
reference should be disabled.
The RA2 pin can be used as a simple D/A output with
limited drive capability. Due to the limited current drive
capability, a buffer must be used on the voltage
reference output for external connections to VREF.
Figure 21-2 shows an example buffering technique.
DS39631A-page 240
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 21-2:
VOLTAGE REFERENCE OUTPUT BUFFER EXAMPLE
PIC18FXXXX
CVREF
Module
(1)
R
+
–
CVREF Output
RA2
Voltage
Reference
Output
Impedance
Note 1: R is dependent upon the voltage reference configuration bits, CVRCON<3:0> and CVRCON<5>.
TABLE 21-1: REGISTERS ASSOCIATED WITH COMPARATOR VOLTAGE REFERENCE
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
CVRCON
CMCON
TRISA
CVREN
C2OUT
CVROE
C1OUT
CVRR
C2INV
CVRSS
C1INV
CVR3
CIS
CVR2
CM2
CVR1
CM1
CVR0
CM0
51
51
52
TRISA7(1) TRISA6(1) PORTA Data Direction Control Register
Legend: Shaded cells are not used with the comparator voltage reference.
Note 1: PORTA pins are enabled based on oscillator configuration.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 241
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 242
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
The High/Low-Voltage Detect Control register
(Register 22-1) completely controls the operation of the
HLVD module. This allows the circuitry to be “turned
22.0 HIGH/LOW-VOLTAGE
DETECT (HLVD)
off” by the user under software control, which
minimizes the current consumption for the device.
PIC18F2420/2520/4420/4520
devices
have
a
High/Low-Voltage Detect module (HLVD). This is a pro-
grammable circuit that allows the user to specify both a
device voltage trip point and the direction of change from
that point. If the device experiences an excursion past
the trip point in that direction, an interrupt flag is set. If the
interrupt is enabled, the program execution will branch to
the interrupt vector address and the software can then
respond to the interrupt.
The block diagram for the HLVD module is shown in
Figure 22-1.
REGISTER 22-1: HLVDCON REGISTER (HIGH/LOW-VOLTAGE DETECT CONTROL)
R/W-0
VDIRMAG
bit 7
U-0
—
R-0
R/W-0
R/W-0
R/W-1
R/W-0
R/W-1
IRVST
HLVDEN HLVDL3(1) HLVDL2(1) HLVDL1(1) HLVDL0(1)
bit 0
bit 7
VDIRMAG: Voltage Direction Magnitude Select bit
1= Event occurs when voltage equals or exceeds trip point (HLVDL3:HLDVL0)
0= Event occurs when voltage equals or falls below trip point (HLVDL3:HLVDL0)
bit 6
bit 5
Unimplemented: Read as ‘0’
IRVST: Internal Reference Voltage Stable Flag bit
1= Indicates that the voltage detect logic will generate the interrupt flag at the specified voltage
range
0= Indicates that the voltage detect logic will not generate the interrupt flag at the specified
voltage range and the HLVD interrupt should not be enabled
bit 4
HLVDEN: High/Low-Voltage Detect Power Enable bit
1= HLVD enabled
0= HLVD disabled
bit 3-0
HLVDL3:HLVDL0: Voltage Detection Limit bits(1)
1111= External analog input is used (input comes from the HLVDIN pin)
1110= Maximum setting
.
.
.
0000= Minimum setting
Note 1: See Table 26-4 for specifications.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
2004 Microchip Technology Inc.
DS39631A-page 243
PIC18F2420/2520/4420/4520
The module is enabled by setting the HLVDEN bit.
Each time that the HLVD module is enabled, the cir-
cuitry requires some time to stabilize. The IRVST bit is
a read-only bit and is used to indicate when the circuit
is stable. The module can only generate an interrupt
after the circuit is stable and IRVST is set.
event, depending on the configuration of the module.
When the supply voltage is equal to the trip point, the
voltage tapped off of the resistor array is equal to the
internal reference voltage generated by the voltage
reference module. The comparator then generates an
interrupt signal by setting the HLVDIF bit.
The VDIRMAG bit determines the overall operation of
the module. When VDIRMAG is cleared, the module
monitors for drops in VDD below a predetermined set
point. When the bit is set, the module monitors for rises
in VDD above the set point.
The trip point voltage is software programmable to any one
of 16 values. The trip point is selected by programming the
HLVDL3:HLVDL0 bits (HLVDCON<3:0>).
The HLVD module has an additional feature that allows
the user to supply the trip voltage to the module from an
external source. This mode is enabled when bits
HLVDL3:HLVDL0 are set to ‘1111’. In this state, the
comparator input is multiplexed from the external input
pin, HLVDIN. This gives users flexibility because it
allows them to configure the High/Low-Voltage Detect
interrupt to occur at any voltage in the valid operating
range.
22.1 Operation
When the HLVD module is enabled, a comparator uses
an internally generated reference voltage as the set
point. The set point is compared with the trip point,
where each node in the resistor divider represents a
trip point voltage. The “trip point” voltage is the voltage
level at which the device detects a high or low-voltage
FIGURE 22-1:
HLVD MODULE BLOCK DIAGRAM (WITH EXTERNAL INPUT)
Externally Generated
Trip Point
VDD
VDD
HLVDL3:HLVDL0
HLVDCON
Register
HLVDIN
VDIRMAG
HLVDEN
HLVDIN
Set
HLVDIF
HLVDEN
BOREN
Internal Voltage
Reference
DS39631A-page 244
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
Depending on the application, the HLVD module does
not need to be operating constantly. To decrease the
current requirements, the HLVD circuitry may only
need to be enabled for short periods where the voltage
is checked. After doing the check, the HLVD module
may be disabled.
22.2 HLVD Setup
The following steps are needed to set up the HLVD
module:
1. Write the value to the HLVDL3:HLVDL0 bits that
selects the desired HLVD trip point.
2. Set the VDIRMAG bit to detect high voltage
22.4 HLVD Start-up Time
(VDIRMAG = 1) or low voltage (VDIRMAG = 0).
3. Enable the HLVD module by setting the
HLVDEN bit.
The internal reference voltage of the HLVD module,
specified in electrical specification parameter D420,
may be used by other internal circuitry, such as the
Programmable Brown-out Reset. If the HLVD or other
circuits using the voltage reference are disabled to
lower the device’s current consumption, the reference
voltage circuit will require time to become stable before
a low or high-voltage condition can be reliably
detected. This start-up time, TIRVST, is an interval that
is independent of device clock speed. It is specified in
electrical specification parameter 36.
4. Clear the HLVD interrupt flag (PIR2<2>), which
may have been set from a previous interrupt.
5. Enable the HLVD interrupt if interrupts are
desired by setting the HLVDIE and GIE bits
(PIE2<2> and INTCON<7>). An interrupt will not
be generated until the IRVST bit is set.
22.3 Current Consumption
When the module is enabled, the HLVD comparator
and voltage divider are enabled and will consume static
current. The total current consumption, when enabled,
is specified in electrical specification parameter D022B.
The HLVD interrupt flag is not enabled until TIRVST has
expired and a stable reference voltage is reached. For
this reason, brief excursions beyond the set point may
not be detected during this interval. Refer to
Figure 22-2 or Figure 22-3.
FIGURE 22-2:
LOW-VOLTAGE DETECT OPERATION (VDIRMAG = 0)
CASE 1:
HLVDIF may not be set
VDD
VLVD
HLVDIF
Enable HLVD
IRVST
TIVRST
HLVDIF cleared in software
Internal Reference is stable
CASE 2:
VDD
VLVD
HLVDIF
Enable HLVD
TIVRST
IRVST
Internal Reference is stable
HLVDIF cleared in software
HLVDIF cleared in software,
HLVDIF remains set since HLVD condition still exists
2004 Microchip Technology Inc.
DS39631A-page 245
PIC18F2420/2520/4420/4520
FIGURE 22-3:
HIGH-VOLTAGE DETECT OPERATION (VDIRMAG = 1)
CASE 1:
HLVDIF may not be set
VLVD
VDD
HLVDIF
Enable HLVD
IRVST
TIVRST
HLVDIF cleared in software
Internal Reference is stable
CASE 2:
VLVD
VDD
HLVDIF
Enable HLVD
TIVRST
IRVST
Internal Reference is stable
HLVDIF cleared in software
HLVDIF cleared in software,
HLVDIF remains set since HLVD condition still exists
FIGURE 22-4:
TYPICAL LOW-VOLTAGE
DETECT APPLICATION
22.5 Applications
In many applications, the ability to detect a drop below
or rise above a particular threshold is desirable. For
example, the HLVD module could be periodically
enabled to detect Universal Serial Bus (USB) attach or
detach. This assumes the device is powered by a lower
voltage source than the USB when detached. An attach
would indicate a high-voltage detect from, for example,
3.3V to 5V (the voltage on USB) and vice versa for a
detach. This feature could save a design a few extra
components and an attach signal (input pin).
VA
VB
For general battery applications, Figure 22-4 shows a
possible voltage curve. Over time, the device voltage
decreases. When the device voltage reaches voltage
VA, the HLVD logic generates an interrupt at time TA.
The interrupt could cause the execution of an ISR,
which would allow the application to perform “house-
keeping tasks” and perform a controlled shutdown
before the device voltage exits the valid operating
range at TB. The HLVD, thus, would give the applica-
tion a time window, represented by the difference
between TA and TB, to safely exit.
TB
VA = HLVD trip point
VB = Minimum valid device
operating voltage
TA
Time
Legend:
DS39631A-page 246
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
22.6 Operation During Sleep
22.7 Effects of a Reset
When enabled, the HLVD circuitry continues to operate
during Sleep. If the device voltage crosses the trip
point, the HLVDIF bit will be set and the device will
wake-up from Sleep. Device execution will continue
from the interrupt vector address if interrupts have
been globally enabled.
A device Reset forces all registers to their Reset state.
This forces the HLVD module to be turned off.
TABLE 22-1: REGISTERS ASSOCIATED WITH HIGH/LOW-VOLTAGE DETECT MODULE
Reset
Values
on Page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
HLVDCON VDIRMAG
—
IRVST
HLVDEN HLVDL3 HLVDL2 HLVDL1 HLVDL0
50
49
52
52
52
INTCON
PIR2
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
EEIF
RBIE
BCLIF
BCLIE
BCLIP
TMR0IF
HLVDIF
INT0IF
RBIF
OSCFIF
OCSFIE
OSCFIP
CMIF
CMIE
CMIP
—
—
—
TMR3IF CCP2IF
PIE2
EEIE
EEIP
HLVDIE TMR3IE CCP2IE
HLVDIP TMR3IP CCP2IP
IPR2
Legend: — = unimplemented, read as ‘0’. Shaded cells are unused by the HLVD module.
2004 Microchip Technology Inc.
DS39631A-page 247
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 248
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
The inclusion of an internal RC oscillator also provides
the additional benefits of a Fail-Safe Clock Monitor
(FSCM) and Two-Speed Start-up. FSCM provides for
23.0 SPECIAL FEATURES OF
THE CPU
background monitoring of the peripheral clock and
automatic switchover in the event of its failure. Two-
Speed Start-up enables code to be executed almost
immediately on start-up, while the primary clock source
completes its start-up delays.
PIC18F2420/2520/4420/4520 devices include several
features intended to maximize reliability and minimize
cost through elimination of external components. These
are:
• Oscillator Selection
• Resets:
All of these features are enabled and configured by
setting the appropriate configuration register bits.
- Power-on Reset (POR)
- Power-up Timer (PWRT)
- Oscillator Start-up Timer (OST)
- Brown-out Reset (BOR)
• Interrupts
23.1 Configuration Bits
The configuration bits can be programmed (read as ‘0’)
or left unprogrammed (read as ‘1’) to select various
device configurations. These bits are mapped starting
at program memory location 300000h.
• Watchdog Timer (WDT)
• Fail-Safe Clock Monitor
• Two-Speed Start-up
• Code Protection
The user will note that address 300000h is beyond the
user program memory space. In fact, it belongs to the
configuration memory space (300000h-3FFFFFh), which
can only be accessed using table reads and table writes.
• ID Locations
• In-Circuit Serial Programming
Programming the configuration registers is done in a
manner similar to programming the Flash memory. The
WR bit in the EECON1 register starts a self-timed write
to the configuration register. In normal operation mode,
a TBLWT instruction with the TBLPTR pointing to the
configuration register sets up the address and the data
for the configuration register write. Setting the WR bit
starts a long write to the configuration register. The
configuration registers are written a byte at a time. To
write or erase a configuration cell, a TBLWTinstruction
can write a ‘1’ or a ‘0’ into the cell. For additional details
on Flash programming, refer to Section 6.5 “Writing
to Flash Program Memory”.
The oscillator can be configured for the application
depending on frequency, power, accuracy and cost. All
of the options are discussed in detail in Section 2.0
“Oscillator Configurations”.
A complete discussion of device Resets and interrupts
is available in previous sections of this data sheet.
In addition to their Power-up and Oscillator Start-up
Timers provided for Resets, PIC18F2420/2520/4420/
4520 devices have a Watchdog Timer, which is either
permanently enabled via the configuration bits or
software controlled (if configured as disabled).
TABLE 23-1: CONFIGURATION BITS AND DEVICE IDs
Default/
Unprogrammed
Value
File Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
300001h CONFIG1H IESO
FCMEN
—
—
—
FOSC3
BORV0
FOSC2
FOSC1
FOSC0
00-- 0111
---1 1111
---1 1111
1--- -011
10-- -1-1
---- 1111
11-- ----
---- 1111
111- ----
---- 1111
-1-- ----
300002h CONFIG2L
300003h CONFIG2H
—
—
—
—
—
BORV1
BOREN1 BOREN0 PWRTEN
—
WDTPS3 WDTPS2 WDTPS1 WDTPS0 WDTEN
300005h CONFIG3H MCLRE
—
—
—
—
—
LPT1OSC PBADEN CCP2MX
300006h CONFIG4L DEBUG XINST
—
LVP
—
CP1
—
STVREN
CP0
(1)
(1)
300008h CONFIG5L
300009h CONFIG5H
30000Ah CONFIG6L
—
CPD
—
—
CPB
—
—
—
CP3
—
CP2
—
—
—
—
(1)
(1)
(1)
(1)
—
—
WRT3
—
WRT2
—
WRT1
—
WRT0
—
30000Bh CONFIG6H WRTD
WRTB
—
WRTC
—
—
30000Ch CONFIG7L
30000Dh CONFIG7H
—
—
—
EBTR3
—
EBTR2
—
EBTR1
—
EBTR0
—
EBTRB
DEV1
DEV9
—
—
(1)
(2)
3FFFFEh DEVID1
DEV2
DEV10
DEV0
DEV8
REV4
DEV7
REV3
DEV6
REV2
DEV5
REV1
DEV4
REV0
DEV3
xxxx xxxx
(1)
3FFFFFh DEVID2
0000 1100
Legend:
x= unknown, u= unchanged, — = unimplemented, q= value depends on condition.
Shaded cells are unimplemented, read as ‘0’.
Note 1: Unimplemented in PIC18F2420/4420 devices; maintain this bit set.
2: See Register 23-14 for DEVID1 values. DEVID registers are read-only and cannot be programmed by the user.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 249
PIC18F2420/2520/4420/4520
REGISTER 23-1: CONFIG1H:CONFIGURATIONREGISTER1HIGH(BYTEADDRESS300001h)
R/P-0
IESO
R/P-0
U-0
—
U-0
—
R/P-0
R/P-1
R/P-1
R/P-1
FCMEN
FOSC3
FOSC2
FOSC1
FOSC0
bit 7
bit 0
bit 7
bit 6
IESO: Internal/External Oscillator Switchover bit
1= Oscillator Switchover mode enabled
0= Oscillator Switchover mode disabled
FCMEN: Fail-Safe Clock Monitor Enable bit
1= Fail-Safe Clock Monitor enabled
0= Fail-Safe Clock Monitor disabled
bit 5-4 Unimplemented: Read as ‘0’
bit 3-0 FOSC3:FOSC0: Oscillator Selection bits
11xx= External RC oscillator, CLKO function on RA6
101x= External RC oscillator, CLKO function on RA6
1001= Internal oscillator block, CLKO function on RA6, port function on RA7
1000= Internal oscillator block, port function on RA6 and RA7
0111= External RC oscillator, port function on RA6
0110= HS oscillator, PLL enabled (Clock Frequency = 4 x FOSC1)
0101= EC oscillator, port function on RA6
0100= EC oscillator, CLKO function on RA6
0011= External RC oscillator, CLKO function on RA6
0010= HS oscillator
0001= XT oscillator
0000= LP oscillator
Legend:
R = Readable bit
P = Programmable bit U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
u = Unchanged from programmed state
DS39631A-page 250
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 23-2: CONFIG2L:CONFIGURATION REGISTER 2 LOW (BYTE ADDRESS300002h)
U-0
—
U-0
—
U-0
—
R/P-1
R/P-1
R/P-1
R/P-1
R/P-1
BORV1(1) BORV0(1) BOREN1(2) BOREN0(2) PWRTEN(2)
bit 7
bit 0
bit 7-5 Unimplemented: Read as ‘0’
bit 4-3 BORV1:BORV0: Brown-out Reset Voltage bits(1)
11= Maximum setting
.
.
.
00= Minimum setting
bit 2-1 BOREN1:BOREN0: Brown-out Reset Enable bits(2)
11= Brown-out Reset enabled in hardware only (SBOREN is disabled)
10= Brown-out Reset enabled in hardware only and disabled in Sleep mode
(SBOREN is disabled)
01= Brown-out Reset enabled and controlled by software (SBOREN is enabled)
00= Brown-out Reset disabled in hardware and software
bit 0
PWRTEN: Power-up Timer Enable bit(2)
1= PWRT disabled
0= PWRT enabled
Note 1: See Section 26.1 “DC Characteristics: Supply Voltage” for specifications.
2: The Power-up Timer is decoupled from Brown-out Reset, allowing these features to
be independently controlled.
Legend:
R = Readable bit
P = Programmable bit U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
-n = Value when device is unprogrammed
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 251
PIC18F2420/2520/4420/4520
REGISTER 23-3: CONFIG2H: CONFIGURATION REGISTER 2 HIGH (BYTE ADDRESS 300003h)
U-0
—
U-0
—
U-0
—
R/P-1
R/P-1
R/P-1
R/P-1
R/P-1
WDTPS3 WDTPS2 WDTPS1 WDTPS0 WDTEN
bit 0
bit 7
bit 7-5
bit 4-1
Unimplemented: Read as ‘0’
WDTPS3:WDTPS0: Watchdog Timer Postscale Select bits
1111= 1:32,768
1110= 1:16,384
1101= 1:8,192
1100= 1:4,096
1011= 1:2,048
1010= 1:1,024
1001= 1:512
1000= 1:256
0111= 1:128
0110= 1:64
0101= 1:32
0100= 1:16
0011= 1:8
0010= 1:4
0001= 1:2
0000= 1:1
bit 0
WDTEN: Watchdog Timer Enable bit
1= WDT enabled
0= WDT disabled (control is placed on the SWDTEN bit)
Legend:
R = Readable bit
P = Programmable bit U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
u = Unchanged from programmed state
DS39631A-page 252
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 23-4: CONFIG3H: CONFIGURATION REGISTER 3 HIGH (BYTE ADDRESS 300005h)
R/P-1
U-0
—
U-0
—
U-0
—
U-0
—
R/P-0
R/P-1
R/P-1
MCLRE
LPT1OSC PBADEN CCP2MX
bit 0
bit 7
bit 7
MCLRE: MCLR Pin Enable bit
1= MCLR pin enabled; RE3 input pin disabled
0= RE3 input pin enabled; MCLR disabled
bit 6-3 Unimplemented: Read as ‘0’
bit 2
LPT1OSC: Low-Power Timer1 Oscillator Enable bit
1= Timer1 configured for low-power operation
0= Timer1 configured for higher power operation
bit 1
PBADEN: PORTB A/D Enable bit
(Affects ADCON1 Reset state. ADCON1 controls PORTB<4:0> pin configuration.)
1= PORTB<4:0> pins are configured as analog input channels on Reset
0= PORTB<4:0> pins are configured as digital I/O on Reset
bit 0
CCP2MX: CCP2 Mux bit
1= CCP2 input/output is multiplexed with RC1
0= CCP2 input/output is multiplexed with RB3
Legend:
R = Readable bit
P = Programmable bit U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
-n = Value when device is unprogrammed
REGISTER 23-5: CONFIG4L:CONFIGURATION REGISTER 4 LOW (BYTE ADDRESS300006h)
R/P-1
R/P-0
U-0
—
U-0
—
U-0
—
R/P-1
LVP
U-0
—
R/P-1
STVREN
bit 0
DEBUG
XINST
bit 7
bit 7
bit 6
DEBUG: Background Debugger Enable bit
1= Background debugger disabled, RB6 and RB7 configured as general purpose I/O pins
0= Background debugger enabled, RB6 and RB7 are dedicated to In-Circuit Debug
XINST: Extended Instruction Set Enable bit
1= Instruction set extension and Indexed Addressing mode enabled
0= Instruction set extension and Indexed Addressing mode disabled (Legacy mode)
bit 5-3 Unimplemented: Read as ‘0’
bit 2
LVP: Single-Supply ICSP Enable bit
1= Single-Supply ICSP enabled
0= Single-Supply ICSP disabled
bit 1
bit 0
Unimplemented: Read as ‘0’
STVREN: Stack Full/Underflow Reset Enable bit
1= Stack full/underflow will cause Reset
0= Stack full/underflow will not cause Reset
Legend:
R = Readable bit
C = Clearable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
u = Unchanged from programmed state
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 253
PIC18F2420/2520/4420/4520
REGISTER 23-6: CONFIG5L:CONFIGURATION REGISTER 5 LOW (BYTE ADDRESS300008h)
U-0
—
U-0
—
U-0
—
U-0
—
R/C-1
CP3(1,2)
R/C-1
CP2(1)
R/C-1
CP1
R/C-1
CP0
bit 7
bit 0
bit 7-4 Unimplemented: Read as ‘0’
bit 3
bit 2
bit 1
bit 0
CP3: Code Protection bit(1,2)
1= Block 3 (006000-007FFFh) not code-protected
0= Block 3 (006000-007FFFh) code-protected
CP2: Code Protection bit(1)
1= Block 2 (004000-005FFFh) not code-protected
0= Block 2 (004000-005FFFh) code-protected
CP1: Code Protection bit
1= Block 1 (002000-003FFFh) not code-protected
0= Block 1 (002000-003FFFh) code-protected
CP0: Code Protection bit
1= Block 0 (000800-001FFFh) not code-protected
0= Block 0 (000800-001FFFh) code-protected
Note 1: Unimplemented in PIC18F2420/4420 devices; maintain this bit set.
2: Unimplemented in PIC18F2425/4425 devices; maintain this bit set.
Legend:
R = Readable bit
C = Clearable bit
U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
-n = Value when device is unprogrammed
REGISTER 23-7: CONFIG5H:CONFIGURATIONREGISTER5HIGH(BYTEADDRESS300009h)
R/C-1
CPD
R/C-1
CPB
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
bit 7
bit 0
bit 7
bit 6
CPD: Data EEPROM Code Protection bit
1= Data EEPROM not code-protected
0= Data EEPROM code-protected
CPB: Boot Block Code Protection bit
1= Boot block (000000-0007FFh) not code-protected
0= Boot block (000000-0007FFh) code-protected
bit 5-0 Unimplemented: Read as ‘0’
Legend:
R = Readable bit
C = Clearable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
u = Unchanged from programmed state
DS39631A-page 254
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 23-8: CONFIG6L: CONFIGURATION REGISTER 6 LOW (BYTE ADDRESS 30000Ah)
U-0
—
U-0
—
U-0
—
U-0
—
R/C-1
WRT3(1,2) WRT2(1)
R/C-1
R/C-1
WRT1
R/C-1
WRT0
bit 7
bit 0
bit 7-4 Unimplemented: Read as ‘0’
bit 3
bit 2
bit 1
bit 0
WRT3: Write Protection bit(1,2)
1= Block 3 (006000-007FFFh) not write-protected
0= Block 3 (006000-007FFFh) write-protected
WRT2: Write Protection bit(1)
1= Block 2 (004000-005FFFh) not write-protected
0= Block 2 (004000-005FFFh) write-protected
WRT1: Write Protection bit
1= Block 1 (002000-003FFFh) not write-protected
0= Block 1 (002000-003FFFh) write-protected
WRT0: Write Protection bit
1= Block 0 (000800-001FFFh) not write-protected
0= Block 0 (000800-001FFFh) write-protected
Note 1: Unimplemented in PIC18F2420/4420 devices; maintain this bit set.
2: Unimplemented in PIC18F2425/4425 devices; maintain this bit set.
Legend:
R = Readable bit
C = Clearable bit
U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
-n = Value when device is unprogrammed
REGISTER 23-9: CONFIG6H:CONFIGURATION REGISTER6 HIGH(BYTEADDRESS30000Bh)
R/C-1
R/C-1
R-1
WRTC(1)
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
WRTD
WRTB
bit 7
bit 0
bit 7
bit 6
bit 5
WRTD: Data EEPROM Write Protection bit
1= Data EEPROM not write-protected
0= Data EEPROM write-protected
WRTB: Boot Block Write Protection bit
1= Boot block (000000-0007FFh) not write-protected
0= Boot block (000000-0007FFh) write-protected
WRTC: Configuration Register Write Protection bit(1)
1= Configuration registers (300000-3000FFh) not write-protected
0= Configuration registers (300000-3000FFh) write-protected
Note 1: This bit is read-only in normal execution mode; it can be written only in Program mode.
bit 4-0 Unimplemented: Read as ‘0’
Legend:
R = Readable bit
C = Clearable bit
U = Unimplemented bit, read as ‘0’
- n = Value when device is unprogrammed
u = Unchanged from programmed state
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 255
PIC18F2420/2520/4420/4520
REGISTER 23-10: CONFIG7L:CONFIGURATIONREGISTER7LOW(BYTEADDRESS30000Ch)
U-0
—
U-0
—
U-0
—
U-0
—
R/C-1
EBTR3(1,2) EBTR2(1)
R/C-1
R/C-1
R/C-1
EBTR1
EBTR0
bit 7
bit 0
bit 7-4 Unimplemented: Read as ‘0’
bit 3
bit 2
bit 1
bit 0
EBTR3: Table Read Protection bit(1,2)
1= Block 3 (006000-007FFFh) not protected from table reads executed in other blocks
0= Block 3 (006000-007FFFh) protected from table reads executed in other blocks
EBTR2: Table Read Protection bit(1)
1= Block 2 (004000-005FFFh) not protected from table reads executed in other blocks
0= Block 2 (004000-005FFFh) protected from table reads executed in other blocks
EBTR1: Table Read Protection bit
1= Block 1 (002000-003FFFh) not protected from table reads executed in other blocks
0= Block 1 (002000-003FFFh) protected from table reads executed in other blocks
EBTR0: Table Read Protection bit
1= Block 0 (000800-001FFFh) not protected from table reads executed in other blocks
0= Block 0 (000800-001FFFh) protected from table reads executed in other blocks
Note 1: Unimplemented in PIC18F2420/4420 devices; maintain this bit set.
2: Unimplemented in PIC18F2425/4425 devices; maintain this bit set.
Legend:
R = Readable bit
C = Clearable bit
U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
-n = Value when device is unprogrammed
REGISTER 23-11: CONFIG7H:CONFIGURATION REGISTER7 HIGH(BYTEADDRESS30000Dh)
U-0
—
R/C-1
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
EBTRB
bit 7
bit 0
bit 7
bit 6
Unimplemented: Read as ‘0’
EBTRB: Boot Block Table Read Protection bit
1= Boot block (000000-0007FFh) not protected from table reads executed in other blocks
0= Boot block (000000-0007FFh) protected from table reads executed in other blocks
bit 5-0 Unimplemented: Read as ‘0’
Legend:
R = Readable bit
C = Clearable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
u = Unchanged from programmed state
DS39631A-page 256
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 23-12: DEVID1: DEVICE ID REGISTER 1 FOR PIC18F2420/2520/4420/4520
R
R
R
R
R
R
R
R
DEV2
DEV1
DEV0
REV4
REV3
REV2
REV1
REV0
bit 7
bit 0
bit 7-5 DEV2:DEV0: Device ID bits
000= PIC18F4520
010= PIC18F4420
100= PIC18F2520
110= PIC18F2420
bit 4-0 REV4:REV0: Revision ID bits
These bits are used to indicate the device revision.
Legend:
R = Read-only bit
P = Programmable bit U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
-n = Value when device is unprogrammed
REGISTER 23-13: DEVID2: DEVICE ID REGISTER 2 FOR PIC18F2420/2520/4420/4520
R
R
R
R
R
R
R
R
DEV10
DEV9
DEV8
DEV7
DEV6
DEV5
DEV4
DEV3
bit 7
bit 0
bit 7-0 DEV10:DEV3: Device ID bits
These bits are used with the DEV2:DEV0 bits in the Device ID Register 1 to identify the
part number.
0000 1100= PIC18F2420/2520/4420/4520 devices
Note:
These values for DEV10:DEV3 may be shared with other devices. The specific
device is always identified by using the entire DEV10:DEV0 bit sequence.
Legend:
R = Read-only bit
P = Programmable bit U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
-n = Value when device is unprogrammed
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 257
PIC18F2420/2520/4420/4520
23.2 Watchdog Timer (WDT)
Note 1: The CLRWDT and SLEEP instructions
clear the WDT and postscaler counts
when executed.
For PIC18F2420/2520/4420/4520 devices, the WDT is
driven by the INTRC source. When the WDT is
enabled, the clock source is also enabled. The nominal
WDT period is 4 ms and has the same stability as the
INTRC oscillator.
2: Changing the setting of the IRCF bits
(OSCCON<6:4>) clears the WDT and
postscaler counts.
The 4 ms period of the WDT is multiplied by a 16-bit
postscaler. Any output of the WDT postscaler is
selected by a multiplexer, controlled by bits in Configu-
ration Register 2H. Available periods range from 4 ms
to 131.072 seconds (2.18 minutes). The WDT and
postscaler are cleared when any of the following events
occur: a SLEEPor CLRWDTinstruction is executed, the
IRCF bits (OSCCON<6:4>) are changed or a clock
failure has occurred.
3: When a CLRWDTinstruction is executed,
the postscaler count will be cleared.
23.2.1
CONTROL REGISTER
Register 23-14 shows the WDTCON register. This is a
readable and writable register which contains a control
bit that allows software to override the WDT enable
configuration bit, but only if the configuration bit has
disabled the WDT.
FIGURE 23-1:
WDT BLOCK DIAGRAM
Enable WDT
SWDTEN
WDTEN
WDT Counter
Wake-up
from Power
Managed Modes
÷128
INTRC Source
Change on IRCF bits
CLRWDT
WDT
Reset
Reset
Programmable Postscaler
1:1 to 1:32,768
All Device Resets
4
WDTPS<3:0>
Sleep
DS39631A-page 258
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
REGISTER 23-14: WDTCON REGISTER
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
R/W-0
SWDTEN(1)
bit 0
bit 7
bit 7-1 Unimplemented: Read as ‘0’
bit 0
SWDTEN: Software Controlled Watchdog Timer Enable bit(1)
1= Watchdog Timer is on
0= Watchdog Timer is off
Note 1: This bit has no effect if the configuration bit, WDTEN, is enabled.
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
TABLE 23-2: SUMMARY OF WATCHDOG TIMER REGISTERS
Reset
Values
on page
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RCON
WDTCON
IPEN
—
SBOREN
—
—
—
RI
—
TO
—
PD
—
POR
—
BOR
48
50
SWDTEN
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Watchdog Timer.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 259
PIC18F2420/2520/4420/4520
In all other power managed modes, Two-Speed Start-
23.3 Two-Speed Start-up
up is not used. The device will be clocked by the
currently selected clock source until the primary clock
source becomes available. The setting of the IESO bit
is ignored.
The Two-Speed Start-up feature helps to minimize the
latency period from oscillator start-up to code execution
by allowing the microcontroller to use the INTOSC
oscillator as a clock source until the primary clock
source is available. It is enabled by setting the IESO
configuration bit.
23.3.1
SPECIAL CONSIDERATIONS FOR
USING TWO-SPEED START-UP
Two-Speed Start-up should be enabled only if the
primary oscillator mode is LP, XT, HS or HSPLL
(crystal-based modes). Other sources do not require
an OST start-up delay; for these, Two-Speed Start-up
should be disabled.
While using the INTOSC oscillator in Two-Speed Start-
up, the device still obeys the normal command
sequences for entering power managed modes,
including multiple SLEEP instructions (refer to
Section 3.1.4 “Multiple Sleep Commands”). In
practice, this means that user code can change the
SCS1:SCS0 bit settings or issue SLEEP instructions
before the OST times out. This would allow an
application to briefly wake-up, perform routine
“housekeeping” tasks and return to Sleep before the
device starts to operate from the primary oscillator.
When enabled, Resets and wake-ups from Sleep mode
cause the device to configure itself to run from the
internal oscillator block as the clock source, following
the time-out of the Power-up Timer after a Power-on
Reset is enabled. This allows almost immediate code
execution while the primary oscillator starts and the
OST is running. Once the OST times out, the device
automatically switches to PRI_RUN mode.
User code can also check if the primary clock source is
currently providing the device clocking by checking the
status of the OSTS bit (OSCCON<3>). If the bit is set,
the primary oscillator is providing the clock. Otherwise,
the internal oscillator block is providing the clock during
wake-up from Reset or Sleep mode.
To use a higher clock speed on wake-up, the INTOSC
or postscaler clock sources can be selected to provide
a higher clock speed by setting bits IRCF2:IRCF0
immediately after Reset. For wake-ups from Sleep, the
INTOSC or postscaler clock sources can be selected
by setting the IRCF2:IRCF0 bits prior to entering Sleep
mode.
FIGURE 23-2:
TIMING TRANSITION FOR TWO-SPEED START-UP (INTOSC TO HSPLL)
Q3
Q4
Q1
Q2 Q3 Q4 Q1 Q2 Q3
Q1
Q2
INTOSC
Multiplexer
OSC1
(1)
TOST
(1)
TPLL
1
2
n-1
n
PLL Clock
Output
Clock
Transition(2)
CPU Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
PC + 6
PC + 4
OSTS bit Set
Wake from Interrupt Event
Note 1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
2: Clock transition typically occurs within 2-4 TOSC.
DS39631A-page 260
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
an alternate power managed mode. This can be done to
attempt a partial recovery or execute a controlled shut-
down. See Section 3.1.4 “Multiple Sleep Commands”
and Section 23.3.1 “Special Considerations for
Using Two-Speed Start-up” for more details.
23.4 Fail-Safe Clock Monitor
The Fail-Safe Clock Monitor (FSCM) allows the
microcontroller to continue operation in the event of an
external oscillator failure by automatically switching the
device clock to the internal oscillator block. The FSCM
function is enabled by setting the FCMEN configuration
bit.
To use a higher clock speed on wake-up, the INTOSC or
postscaler clock sources can be selected to provide a
higher clock speed by setting bits, IRCF2:IRCF0, immedi-
ately after Reset. For wake-ups from Sleep, the INTOSC
or postscaler clock sources can be selected by setting the
IRCF2:IRCF0 bits prior to entering Sleep mode.
When FSCM is enabled, the INTRC oscillator runs at
all times to monitor clocks to peripherals and provide a
backup clock in the event of a clock failure. Clock
monitoring (shown in Figure 23-3) is accomplished by
creating a sample clock signal, which is the INTRC out-
put divided by 64. This allows ample time between
FSCM sample clocks for a peripheral clock edge to
occur. The peripheral device clock and the sample
clock are presented as inputs to the Clock Monitor latch
(CM). The CM is set on the falling edge of the device
clock source, but cleared on the rising edge of the
sample clock.
The FSCM will detect failures of the primary or second-
ary clock sources only. If the internal oscillator block
fails, no failure would be detected, nor would any action
be possible.
23.4.1
FSCM AND THE WATCHDOG TIMER
Both the FSCM and the WDT are clocked by the
INTRC oscillator. Since the WDT operates with a sep-
arate divider and counter, disabling the WDT has no
effect on the operation of the INTRC oscillator when the
FSCM is enabled.
FIGURE 23-3:
FSCM BLOCK DIAGRAM
Clock Monitor
Latch (CM)
(edge-triggered)
As already noted, the clock source is switched to the
INTOSC clock when a clock failure is detected.
Depending on the frequency selected by the
IRCF2:IRCF0 bits, this may mean a substantial change
in the speed of code execution. If the WDT is enabled
with a small prescale value, a decrease in clock speed
allows a WDT time-out to occur and a subsequent
device Reset. For this reason, fail-safe clock events
also reset the WDT and postscaler, allowing it to start
timing from when execution speed was changed and
decreasing the likelihood of an erroneous time-out.
Peripheral
Clock
S
Q
Q
INTRC
Source
C
÷ 64
(32 µs)
488 Hz
(2.048 ms)
Clock
Failure
Detected
23.4.2
EXITING FAIL-SAFE OPERATION
The fail-safe condition is terminated by either a device
Reset or by entering a power managed mode. On
Reset, the controller starts the primary clock source
specified in Configuration Register 1H (with any
required start-up delays that are required for the oscil-
lator mode, such as OST or PLL timer). The INTOSC
multiplexer provides the device clock until the primary
clock source becomes ready (similar to a Two-Speed
Start-up). The clock source is then switched to the pri-
mary clock (indicated by the OSTS bit in the OSCCON
register becoming set). The Fail-Safe Clock Monitor
then resumes monitoring the peripheral clock.
Clock failure is tested for on the falling edge of the sam-
ple clock. If a sample clock falling edge occurs while
CM is still set, a clock failure has been detected
(Figure 23-4). This causes the following:
• the FSCM generates an oscillator fail interrupt by
setting bit, OSCFIF (PIR2<7>);
• the device clock source is switched to the internal
oscillator block (OSCCON is not updated to show
the current clock source – this is the fail-safe
condition) and
• the WDT is reset.
The primary clock source may never become ready dur-
ing start-up. In this case, operation is clocked by the
INTOSC multiplexer. The OSCCON register will remain
in its Reset state until a power managed mode is entered.
During switchover, the postscaler frequency from the
internal oscillator block may not be sufficiently stable for
timing sensitive applications. In these cases, it may be
desirable to select another clock configuration and enter
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 261
PIC18F2420/2520/4420/4520
FIGURE 23-4:
FSCM TIMING DIAGRAM
Sample Clock
Oscillator
Failure
Device
Clock
Output
CM Output
(Q)
Failure
Detected
OSCFIF
CM Test
CM Test
CM Test
Note:
The device clock is normally at a much higher frequency than the sample clock. The relative frequencies in this
example have been chosen for clarity.
time considerably longer than the FCSM sample clock
time, a false clock failure may be detected. To prevent
this, the internal oscillator block is automatically config-
ured as the device clock and functions until the primary
clock is stable (the OST and PLL timers have timed
out). This is identical to Two-Speed Start-up mode.
Once the primary clock is stable, the INTRC returns to
its role as the FSCM source.
23.4.3
FSCM INTERRUPTS IN POWER
MANAGED MODES
By entering a power managed mode, the clock
multiplexer selects the clock source selected by the
OSCCON register. Fail-Safe Monitoring of the power
managed clock source resumes in the power managed
mode.
If an oscillator failure occurs during power managed
operation, the subsequent events depend on whether
or not the oscillator failure interrupt is enabled. If
enabled (OSCFIF = 1), code execution will be clocked
by the INTOSC multiplexer. An automatic transition
back to the failed clock source will not occur.
Note:
The same logic that prevents false oscilla-
tor failure interrupts on POR, or wake from
Sleep, will also prevent the detection of
the oscillator’s failure to start at all follow-
ing these events. This can be avoided by
monitoring the OSTS bit and using a
timing routine to determine if the oscillator
is taking too long to start. Even so, no
oscillator failure interrupt will be flagged.
If the interrupt is disabled, subsequent interrupts while
in Idle mode will cause the CPU to begin executing
instructions while being clocked by the INTOSC
source.
As noted in Section 23.3.1 “Special Considerations
for Using Two-Speed Start-up”, it is also possible to
select another clock configuration and enter an
alternate power managed mode while waiting for the
primary clock to become stable. When the new power
managed mode is selected, the primary clock is
disabled.
23.4.4
POR OR WAKE FROM SLEEP
The FSCM is designed to detect oscillator failure at any
point after the device has exited Power-on Reset
(POR) or low-power Sleep mode. When the primary
device clock is EC, RC or INTRC modes, monitoring
can begin immediately following these events.
For oscillator modes involving a crystal or resonator
(HS, HSPLL, LP or XT), the situation is somewhat
different. Since the oscillator may require a start-up
DS39631A-page 262
Preliminary
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Each of the five blocks has three code protection bits
associated with them. They are:
23.5 Program Verification and
Code Protection
• Code-Protect bit (CPn)
The overall structure of the code protection on the
PIC18 Flash devices differs significantly from other
PICmicro® devices.
• Write-Protect bit (WRTn)
• External Block Table Read bit (EBTRn)
Figure 23-5 shows the program memory organization
for 16 and 32-Kbyte devices and the specific code pro-
tection bit associated with each block. The actual
locations of the bits are summarized in Table 23-3.
The user program memory is divided into five blocks.
One of these is a boot block of 2 Kbytes. The remainder
of the memory is divided into four blocks on binary
boundaries.
FIGURE 23-5:
CODE-PROTECTED PROGRAM MEMORY FOR
PIC18F2420/2520/4420/4520
MEMORY SIZE/DEVICE
Block Code Protection
16 Kbytes
32 Kbytes
Address
Controlled By:
CPB, WRTB, EBTRB
CP0, WRT0, EBTR0
(PIC18F2420/4420) (PIC18F2520/4520) Range
000000h
0007FFh
Boot Block
Block 0
Boot Block
Block 0
000800h
001FFFh
002000h
Block 1
Block 1
Block 2
Block 3
CP1, WRT1, EBTR1
CP2, WRT2, EBTR2
CP3, WRT3, EBTR3
003FFFh
004000h
005FFFh
006000h
007FFFh
Unimplemented
Read ‘0’s
Unimplemented
Read ‘0’s
(Unimplemented Memory Space)
1FFFFFh
TABLE 23-3: SUMMARY OF CODE PROTECTION REGISTERS
File Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
300008h CONFIG5L
300009h CONFIG5H
30000Ah CONFIG6L
—
CPD
—
—
CPB
—
—
—
—
—
—
—
—
—
CP3(1,2)
—
WRT3(1,2) WRT2(1)
CP2(1)
—
CP1
—
CP0
—
—
WRT1
—
WRT0
—
30000Bh CONFIG6H WRTD
WRTB
—
WRTC
—
—
—
30000Ch CONFIG7L
30000Dh CONFIG7H
—
—
EBTR3(1,2) EBTR2(1) EBTR1
EBTR0
—
EBTRB
—
—
—
—
Legend: Shaded cells are unimplemented.
Note 1: Unimplemented in PIC18F2420/4420 devices; maintain this bit set.
2: Unimplemented in PIC18F2425/4425 devices; maintain this bit set.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 263
PIC18F2420/2520/4420/4520
tion that executes from a location outside of that block is
not allowed to read and will result in reading ‘0’s.
Figures 23-6 through 23-8 illustrate table write and table
read protection.
23.5.1
PROGRAM MEMORY
CODE PROTECTION
The program memory may be read to or written from
any location using the table read and table write
instructions. The device ID may be read with table
reads. The configuration registers may be read and
written with the table read and table write instructions.
Note:
Code protection bits may only be written to
a ‘0’ from a ‘1’ state. It is not possible to
write a ‘1’ to a bit in the ‘0’ state. Code pro-
tection bits are only set to ‘1’ by a full chip
erase or block erase function. The full chip
erase and block erase functions can only
be initiated via ICSP or an external
programmer.
In normal execution mode, the CPn bits have no direct
effect. CPn bits inhibit external reads and writes. A block
of user memory may be protected from table writes if the
WRTn configuration bit is ‘0’. The EBTRn bits control
table reads. For a block of user memory with the EBTRn
bit set to ‘0’, a table read instruction that executes from
within that block is allowed to read. A table read instruc-
FIGURE 23-6:
TABLE WRITE (WRTn) DISALLOWED
Register Values
Program Memory
Configuration Bit Settings
000000h
0007FFh
WRTB, EBTRB = 11
000800h
TBLPTR = 0008FFh
PC = 001FFEh
WRT0, EBTR0 = 01
TBLWT*
TBLWT*
001FFFh
002000h
WRT1, EBTR1 = 11
WRT2, EBTR2 = 11
WRT3, EBTR3 = 11
003FFFh
004000h
PC = 005FFEh
005FFFh
006000h
007FFFh
Results: All table writes disabled to Blockn whenever WRTn = 0.
DS39631A-page 264
Preliminary
2004 Microchip Technology Inc.
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FIGURE 23-7:
EXTERNAL BLOCK TABLE READ (EBTRn) DISALLOWED
Program Memory Configuration Bit Settings
Register Values
000000h
WRTB, EBTRB = 11
WRT0, EBTR0 = 10
0007FFh
000800h
TBLPTR = 0008FFh
001FFFh
002000h
TBLRD*
PC = 003FFEh
WRT1, EBTR1 = 11
WRT2, EBTR2 = 11
003FFFh
004000h
005FFFh
006000h
WRT3, EBTR3 = 11
007FFFh
Results: All table reads from external blocks to Blockn are disabled whenever EBTRn = 0.
TABLAT register returns a value of ‘0’.
FIGURE 23-8:
EXTERNAL BLOCK TABLE READ (EBTRn) ALLOWED
Register Values
Program Memory
Configuration Bit Settings
000000h
WRTB, EBTRB = 11
WRT0, EBTR0 = 10
0007FFh
000800h
TBLPTR = 0008FFh
PC = 001FFEh
TBLRD*
001FFFh
002000h
WRT1, EBTR1 = 11
WRT2, EBTR2 = 11
WRT3, EBTR3 = 11
003FFFh
004000h
005FFFh
006000h
007FFFh
Results: Table reads permitted within Blockn, even when EBTRBn = 0.
TABLAT register returns the value of the data at the location TBLPTR.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 265
PIC18F2420/2520/4420/4520
To use the In-Circuit Debugger function of the micro-
controller, the design must implement In-Circuit Serial
Programming connections to MCLR/VPP/RE3, VDD,
VSS, RB7 and RB6. This will interface to the In-Circuit
Debugger module available from Microchip or one of
the third party development tool companies.
23.5.2
DATA EEPROM
CODE PROTECTION
The entire data EEPROM is protected from external
reads and writes by two bits: CPD and WRTD. CPD
inhibits external reads and writes of data EEPROM.
WRTD inhibits internal and external writes to data
EEPROM. The CPU can always read data EEPROM
under normal operation, regardless of the protection bit
settings.
23.9 Single-Supply ICSP Programming
The LVP configuration bit enables Single-Supply ICSP
Programming (formerly known as Low-Voltage ICSP
Programming or LVP). When Single-Supply Program-
ming is enabled, the microcontroller can be programmed
without requiring high voltage being applied to the
MCLR/VPP/RE3 pin, but the RB5/KBI1/PGM pin is then
dedicated to controlling Program mode entry and is not
available as a general purpose I/O pin.
23.5.3
CONFIGURATION REGISTER
PROTECTION
The configuration registers can be write-protected. The
WRTC bit controls protection of the configuration
registers. In normal execution mode, the WRTC bit is
readable only. WRTC can only be written via ICSP or
an external programmer.
While programming, using Single-Supply Programming
mode, VDD is applied to the MCLR/VPP/RE3 pin as in
normal execution mode. To enter Programming mode,
VDD is applied to the PGM pin.
23.6 ID Locations
Eight memory locations (200000h-200007h) are
designated as ID locations, where the user can store
checksum or other code identification numbers. These
locations are both readable and writable during normal
execution through the TBLRD and TBLWT instructions
or during program/verify. The ID locations can be read
when the device is code-protected.
Note 1: High-voltage programming is always
available, regardless of the state of the
LVP bit or the PGM pin, by applying VIHH
to the MCLR pin.
2: By default, Single-Supply ICSP is
enabled in unprogrammed devices (as
supplied from Microchip) and erased
devices.
23.7
In-Circuit Serial Programming
3: When Single-Supply Programming is
enabled, the RB5 pin can no longer be
used as a general purpose I/O pin.
PIC18F2420/2520/4420/4520 devices can be serially
programmed while in the end application circuit. This is
simply done with two lines for clock and data and three
other lines for power, ground and the programming
voltage. This allows customers to manufacture boards
with unprogrammed devices and then program the
microcontroller just before shipping the product. This
also allows the most recent firmware or a custom
firmware to be programmed.
4: When LVP is enabled, externally pull the
PGM pin to VSS to allow normal program
execution.
If Single-Supply ICSP Programming mode will not be
used, the LVP bit can be cleared. RB5/KBI1/PGM then
becomes available as the digital I/O pin, RB5. The LVP
bit may be set or cleared only when using standard
high-voltage programming (VIHH applied to the MCLR/
VPP/RE3 pin). Once LVP has been disabled, only the
standard high-voltage programming is available and
must be used to program the device.
23.8 In-Circuit Debugger
When the DEBUG configuration bit is programmed to a
‘0’, the In-Circuit Debugger functionality is enabled.
This function allows simple debugging functions when
used with MPLAB® IDE. When the microcontroller has
this feature enabled, some resources are not available
for general use. Table 23-4 shows which resources are
required by the background debugger.
Memory that is not code-protected can be erased using
either a block erase, or erased row by row, then written
at any specified VDD. If code-protected memory is to be
erased, a block erase is required. If a block erase is to
be performed when using Low-Voltage Programming,
the device must be supplied with VDD of 4.5V to 5.5V.
TABLE 23-4: DEBUGGER RESOURCES
I/O pins:
RB6, RB7
2 levels
Stack:
Program Memory:
Data Memory:
512 bytes
10 bytes
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2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
The literal instructions may use some of the following
operands:
24.0 INSTRUCTION SET SUMMARY
PIC18F2420/2520/4420/4520 devices incorporate the
standard set of 75 PIC18 core instructions, as well as an
extended set of 8 new instructions, for the optimization
of code that is recursive or that utilizes a software stack.
The extended set is discussed later in this section.
• A literal value to be loaded into a file register
(specified by ‘k’)
• The desired FSR register to load the literal value
into (specified by ‘f’)
• No operand required
(specified by ‘—’)
24.1 Standard Instruction Set
The control instructions may use some of the following
operands:
The standard PIC18 instruction set adds many
enhancements to the previous PICmicro® instruction
sets, while maintaining an easy migration from these
PICmicro instruction sets. Most instructions are a sin-
gle program memory word (16 bits), but there are four
instructions that require two program memory
locations.
• A program memory address (specified by ‘n’)
• The mode of the CALLor RETURNinstructions
(specified by ‘s’)
• The mode of the table read and table write
instructions (specified by ‘m’)
Each single-word instruction is a 16-bit word divided
into an opcode, which specifies the instruction type and
one or more operands, which further specify the
operation of the instruction.
• No operand required
(specified by ‘—’)
All instructions are a single word, except for four
double-word instructions. These instructions were
made double-word to contain the required information
in 32 bits. In the second word, the 4 MSbs are ‘1’s. If
this second word is executed as an instruction (by
itself), it will execute as a NOP.
The instruction set is highly orthogonal and is grouped
into four basic categories:
• Byte-oriented operations
• Bit-oriented operations
• Literal operations
All single-word instructions are executed in a single
instruction cycle, unless a conditional test is true or the
program counter is changed as a result of the instruc-
tion. In these cases, the execution takes two instruction
cycles, with the additional instruction cycle(s) executed
as a NOP.
• Control operations
The PIC18 instruction set summary in Table 24-2 lists
byte-oriented, bit-oriented, literal and control
operations. Table 24-1 shows the opcode field
descriptions.
The double-word instructions execute in two instruction
cycles.
Most byte-oriented instructions have three operands:
1. The file register (specified by ‘f’)
One instruction cycle consists of four oscillator periods.
Thus, for an oscillator frequency of 4 MHz, the normal
instruction execution time is 1 µs. If a conditional test is
true, or the program counter is changed as a result of
an instruction, the instruction execution time is 2 µs.
Two-word branch instructions (if true) would take 3 µs.
2. The destination of the result (specified by ‘d’)
3. The accessed memory (specified by ‘a’)
The file register designator ‘f’ specifies which file
register is to be used by the instruction. The destination
designator ‘d’ specifies where the result of the opera-
tion is to be placed. If ‘d’ is zero, the result is placed in
the WREG register. If ‘d’ is one, the result is placed in
the file register specified in the instruction.
Figure 24-1 shows the general formats that the instruc-
tions can have. All examples use the convention ‘nnh’
to represent a hexadecimal number.
The Instruction Set Summary, shown in Table 24-2,
lists the standard instructions recognized by the
Microchip Assembler (MPASMTM).
All bit-oriented instructions have three operands:
1. The file register (specified by ‘f’)
2. The bit in the file register (specified by ‘b’)
3. The accessed memory (specified by ‘a’)
Section 24.1.1 “Standard Instruction Set” provides
a description of each instruction.
The bit field designator ‘b’ selects the number of the bit
affected by the operation, while the file register
designator ‘f’ represents the number of the file in which
the bit is located.
2004 Microchip Technology Inc.
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PIC18F2420/2520/4420/4520
TABLE 24-1: OPCODE FIELD DESCRIPTIONS
Field
Description
a
RAM access bit
a = 0: RAM location in Access RAM (BSR register is ignored)
a = 1: RAM bank is specified by BSR register
bbb
BSR
Bit address within an 8-bit file register (0 to 7).
Bank Select Register. Used to select the current RAM bank.
ALU Status bits: Carry, Digit Carry, Zero, Overflow, Negative.
C, DC, Z, OV, N
d
Destination select bit
d = 0: store result in WREG
d = 1: store result in file register f
dest
f
Destination: either the WREG register or the specified register file location.
8-bit Register file address (00h to FFh) or 2-bit FSR designator (0h to 3h).
12-bit Register file address (000h to FFFh). This is the source address.
12-bit Register file address (000h to FFFh). This is the destination address.
Global Interrupt Enable bit.
f
f
s
d
GIE
k
Literal field, constant data or label (may be either an 8-bit, 12-bit or a 20-bit value).
Label name.
label
mm
The mode of the TBLPTR register for the table read and table write instructions.
Only used with table read and table write instructions:
*
No change to register (such as TBLPTR with table reads and writes)
Post-Increment register (such as TBLPTR with table reads and writes)
Post-Decrement register (such as TBLPTR with table reads and writes)
Pre-Increment register (such as TBLPTR with table reads and writes)
*+
*-
+*
n
The relative address (2’s complement number) for relative branch instructions or the direct address for
Call/Branch and Return instructions.
PC
Program Counter.
PCL
Program Counter Low Byte.
Program Counter High Byte.
Program Counter High Byte Latch.
Program Counter Upper Byte Latch.
Power-down bit.
PCH
PCLATH
PCLATU
PD
PRODH
PRODL
s
Product of Multiply High Byte.
Product of Multiply Low Byte.
Fast Call/Return mode select bit
s = 0: do not update into/from shadow registers
s = 1: certain registers loaded into/from shadow registers (Fast mode)
TBLPTR
TABLAT
TO
21-bit Table Pointer (points to a Program Memory location).
8-bit Table Latch.
Time-out bit.
TOS
u
Top-of-Stack.
Unused or unchanged.
Watchdog Timer.
WDT
WREG
x
Working register (accumulator).
Don’t care (‘0’ or ‘1’). The assembler will generate code with x = 0. It is the recommended form of use for
compatibility with all Microchip software tools.
z
z
{
7-bit offset value for indirect addressing of register files (source).
7-bit offset value for indirect addressing of register files (destination).
Optional argument.
s
d
}
[text]
(text)
[expr]<n>
→
Indicates an indexed address.
The contents of text.
Specifies bit nof the register indicated by the pointer expr.
Assigned to.
< >
Register bit field.
∈
In the set of.
italics
User defined term (font is Courier).
DS39631A-page 268
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2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 24-1:
GENERAL FORMAT FOR INSTRUCTIONS
Byte-oriented file register operations
15 10
OPCODE f (FILE #)
Example Instruction
9
8
7
0
ADDWF MYREG, W, B
d
a
d = 0for result destination to be WREG register
d = 1for result destination to be file register (f)
a = 0to force Access Bank
a = 1for BSR to select bank
f = 8-bit file register address
Byte to Byte move operations (2-word)
15
12 11
0
0
OPCODE
f (Source FILE #)
MOVFF MYREG1, MYREG2
15
12 11
1111
f (Destination FILE #)
f = 12-bit file register address
Bit-oriented file register operations
15 12 11 9 8
OPCODE b (BIT #)
7
0
BSF MYREG, bit, B
a
f (FILE #)
b = 3-bit position of bit in file register (f)
a = 0to force Access Bank
a = 1for BSR to select bank
f = 8-bit file register address
Literal operations
15
8
7
0
MOVLW 7Fh
OPCODE
k (literal)
k = 8-bit immediate value
Control operations
CALL, GOTO and Branch operations
15
8 7
0
GOTO Label
OPCODE
12 11
n<7:0> (literal)
15
0
1111
n<19:8> (literal)
n = 20-bit immediate value
15
15
8
7
0
CALL MYFUNC
OPCODE
12 11
n<7:0> (literal)
S
0
1111
n<19:8> (literal)
S = Fast bit
15
11 10
0
0
BRA MYFUNC
BC MYFUNC
OPCODE
n<10:0> (literal)
15
OPCODE
8 7
n<7:0> (literal)
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 269
PIC18F2420/2520/4420/4520
TABLE 24-2: PIC18FXXXX INSTRUCTION SET
16-Bit Instruction Word
Mnemonic,
Operands
Status
Affected
Description
Cycles
Notes
MSb
LSb
BYTE-ORIENTED OPERATIONS
ADDWF f, d, a Add WREG and f
ADDWFC f, d, a Add WREG and CARRY bit to f
1
1
1
1
1
0010 01da0 ffff
ffff C, DC, Z, OV, N
ffff C, DC, Z, OV, N
ffff Z, N
1, 2
1, 2
1,2
2
1, 2
4
4
1, 2
1, 2, 3, 4
1, 2, 3, 4
1, 2
1, 2, 3, 4
4
1, 2
1, 2
1
0010 0da
0001 01da
0110 101a
0001 11da
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ffff
ANDWF
CLRF
COMF
f, d, a AND WREG with f
f, a Clear f
f, d, a Complement f
ffff
Z
ffff Z, N
ffff None
ffff None
ffff None
ffff C, DC, Z, OV, N
ffff None
ffff None
ffff C, DC, Z, OV, N
ffff None
ffff None
ffff Z, N
ffff Z, N
ffff None
ffff
ffff None
ffff None
CPFSEQ
CPFSGT
CPFSLT
DECF
f, a
f, a
f, a
Compare f with WREG, skip =
Compare f with WREG, skip >
Compare f with WREG, skip <
1 (2 or 3) 0110 001a
1 (2 or 3) 0110 010a
1 (2 or 3) 0110 000a
f, d, a Decrement f
1
0000 01da
DECFSZ
DCFSNZ
INCF
f, d, a Decrement f, Skip if 0
f, d, a Decrement f, Skip if Not 0
f, d, a Increment f
1 (2 or 3) 0010 11da
1 (2 or 3) 0100 11da
1
1 (2 or 3) 0011 11da
1 (2 or 3) 0100 10da
1
1
2
0010 10da
INCFSZ
INFSNZ
IORWF
MOVF
f, d, a Increment f, Skip if 0
f, d, a Increment f, Skip if Not 0
f, d, a Inclusive OR WREG with f
f, d, a Move f
0001 00da
0101 00da
1100 ffff
1111 ffff
0110 111a
0000 001a
0110 110a
0011 01da
0100 01da
0011 00da
0100 00da
0110 100a
0101 01da
MOVFF
f , f
Move f (source) to 1st word
s
d
s
f (destination) 2nd word
d
MOVWF
MULWF
NEGF
f, a
f, a
f, a
Move WREG to f
Multiply WREG with f
Negate f
1
1
1
1
1
1
1
1
1
1, 2
1, 2
ffff C, DC, Z, OV, N
ffff C, Z, N
ffff Z, N
ffff C, Z, N
ffff Z, N
RLCF
RLNCF
RRCF
RRNCF
SETF
f, d, a Rotate Left f through Carry
f, d, a Rotate Left f (No Carry)
f, d, a Rotate Right f through Carry
f, d, a Rotate Right f (No Carry)
f, a
Set f
ffff None
ffff C, DC, Z, OV, N
1, 2
1, 2
SUBFWB f, d, a Subtract f from WREG with
borrow
SUBWF
f, d, a Subtract WREG from f
1
1
0101 11da
0101 10da
ffff
ffff
ffff C, DC, Z, OV, N
ffff C, DC, Z, OV, N
SUBWFB f, d, a Subtract WREG from f with
borrow
SWAPF
TSTFSZ
XORWF
f, d, a Swap nibbles in f
f, a Test f, skip if 0
f, d, a Exclusive OR WREG with f
1
0011 10da
ffff
ffff
ffff
ffff None
ffff None
ffff Z, N
4
1, 2
1 (2 or 3) 0110 011a
0001 10da
1
Note 1: When a Port register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value
present on the pins themselves. For example, if the data latch is ‘1’ for a pin configured as input and is driven low by an
external device, the data will be written back with a ‘0’.
2: If this instruction is executed on the TMR0 register (and where applicable, ‘d’ = 1), the prescaler will be cleared if
assigned.
3: If Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second cycle is
executed as a NOP.
4: Some instructions are two-word instructions. The second word of these instructions will be executed as a NOPunless the
first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory
locations have a valid instruction.
DS39631A-page 270
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 24-2: PIC18FXXXX INSTRUCTION SET (CONTINUED)
16-Bit Instruction Word
Mnemonic,
Operands
Status
Affected
Description
Cycles
Notes
MSb LSb
BIT-ORIENTED OPERATIONS
BCF
BSF
BTFSC
BTFSS
BTG
f, b, a Bit Clear f
f, b, a Bit Set f
f, b, a Bit Test f, Skip if Clear
f, b, a Bit Test f, Skip if Set
f, d, a Bit Toggle f
1
1
1001 bbba
1000 bbba
ffff
ffff
ffff
ffff
ffff
ffff None
ffff None
ffff None
ffff None
ffff None
1, 2
1, 2
3, 4
3, 4
1, 2
1 (2 or 3) 1011 bbba
1 (2 or 3) 1010 bbba
1
0111 bbba
CONTROL OPERATIONS
BC
BN
n
n
n
n
n
n
n
n
Branch if Carry
1 (2)
1 (2)
1 (2)
1 (2)
1 (2)
1 (2)
1 (2)
2
1110 0010
1110 0110
1110 0011
1110 0111
1110 0101
1110 0001
1110 0100
1101 0nnn
1110 0000
1110 110s
1111 kkkk
0000 0000
0000 0000
1110 1111
1111 kkkk
0000 0000
1111 xxxx
0000 0000
0000 0000
1101 1nnn
0000 0000
0000 0000
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
nnnn
kkkk
kkkk
0000
0000
kkkk
kkkk
0000
xxxx
0000
0000
nnnn
1111
0001
nnnn None
nnnn None
nnnn None
nnnn None
nnnn None
nnnn None
nnnn None
nnnn None
nnnn None
kkkk None
kkkk
Branch if Negative
Branch if Not Carry
Branch if Not Negative
Branch if Not Overflow
Branch if Not Zero
Branch if Overflow
Branch Unconditionally
Branch if Zero
Call subroutine 1st word
2nd word
Clear Watchdog Timer
Decimal Adjust WREG
Go to address 1st word
2nd word
BNC
BNN
BNOV
BNZ
BOV
BRA
BZ
n
n, s
1 (2)
2
CALL
CLRWDT
DAW
GOTO
—
—
n
1
1
2
0100 TO, PD
0111
C
kkkk None
kkkk
NOP
NOP
POP
PUSH
RCALL
RESET
RETFIE
—
—
—
—
n
No Operation
No Operation
1
1
1
1
2
1
2
0000 None
xxxx None
0110 None
0101 None
nnnn None
1111 All
4
Pop top of return stack (TOS)
Push top of return stack (TOS)
Relative Call
Software device Reset
Return from interrupt enable
s
000s GIE/GIEH,
PEIE/GIEL
RETLW
RETURN
SLEEP
k
s
—
Return with literal in WREG
Return from Subroutine
Go into Standby mode
2
2
1
0000 1100
0000 0000
0000 0000
kkkk
0001
0000
kkkk None
001s None
0011 TO, PD
Note 1: When a Port register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value
present on the pins themselves. For example, if the data latch is ‘1’ for a pin configured as input and is driven low by an
external device, the data will be written back with a ‘0’.
2: If this instruction is executed on the TMR0 register (and where applicable, ‘d’ = 1), the prescaler will be cleared if
assigned.
3: If Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second cycle is
executed as a NOP.
4: Some instructions are two-word instructions. The second word of these instructions will be executed as a NOPunless the
first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory
locations have a valid instruction.
2004 Microchip Technology Inc.
Preliminary
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PIC18F2420/2520/4420/4520
TABLE 24-2: PIC18FXXXX INSTRUCTION SET (CONTINUED)
16-Bit Instruction Word
Mnemonic,
Operands
Status
Affected
Description
Cycles
Notes
MSb
LSb
LITERAL OPERATIONS
ADDLW
ANDLW
IORLW
LFSR
k
k
k
f, k
Add literal and WREG
AND literal with WREG
Inclusive OR literal with WREG
Move literal (12-bit) 2nd word
1
1
1
2
0000 1111 kkkk
0000 1011 kkkk
0000 1001 kkkk
1110 1110 00ff
1111 0000 kkkk
0000 0001 0000
0000 1110 kkkk
0000 1101 kkkk
0000 1100 kkkk
0000 1000 kkkk
0000 1010 kkkk
kkkk C, DC, Z, OV, N
kkkk Z, N
kkkk Z, N
kkkk None
kkkk
kkkk None
kkkk None
kkkk None
kkkk None
kkkk C, DC, Z, OV, N
kkkk Z, N
to FSR(f)
1st word
MOVLB
MOVLW
MULLW
RETLW
SUBLW
XORLW
k
k
k
k
k
k
Move literal to BSR<3:0>
Move literal to WREG
Multiply literal with WREG
Return with literal in WREG
Subtract WREG from literal
Exclusive OR literal with WREG
1
1
1
2
1
1
DATA MEMORY ↔ PROGRAM MEMORY OPERATIONS
TBLRD*
Table Read
2
0000 0000 0000
0000 0000 0000
0000 0000 0000
0000 0000 0000
0000 0000 0000
0000 0000 0000
0000 0000 0000
0000 0000 0000
1000 None
1001 None
1010 None
1011 None
1100 None
1101 None
1110 None
1111 None
TBLRD*+
TBLRD*-
TBLRD+*
TBLWT*
TBLWT*+
TBLWT*-
TBLWT+*
Table Read with post-increment
Table Read with post-decrement
Table Read with pre-increment
Table Write
Table Write with post-increment
Table Write with post-decrement
Table Write with pre-increment
2
Note 1: When a Port register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value
present on the pins themselves. For example, if the data latch is ‘1’ for a pin configured as input and is driven low by an
external device, the data will be written back with a ‘0’.
2: If this instruction is executed on the TMR0 register (and where applicable, ‘d’ = 1), the prescaler will be cleared if
assigned.
3: If Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second cycle is
executed as a NOP.
4: Some instructions are two-word instructions. The second word of these instructions will be executed as a NOPunless the
first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory
locations have a valid instruction.
DS39631A-page 272
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
24.1.1
STANDARD INSTRUCTION SET
ADDLW
ADD literal to W
ADDWF
ADD W to f
Syntax:
ADDLW
k
Syntax:
ADDWF
f {,d {,a}}
Operands:
Operation:
Status Affected:
Encoding:
Description:
0 ≤ k ≤ 255
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
(W) + k → W
N, OV, C, DC, Z
Operation:
(W) + (f) → dest
0000
1111
kkkk
kkkk
Status Affected:
Encoding:
N, OV, C, DC, Z
The contents of W are added to the
8-bit literal ‘k’ and the result is placed in
W.
0010
01da
ffff
ffff
Description:
Add W to register ‘f’. If ‘d’ is ‘0’, the
result is stored in W. If ‘d’ is ‘1’, the
result is stored back in register ‘f’
(default).
Words:
Cycles:
1
1
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to W
Example:
ADDLW
15h
Before Instruction
10h
After Instruction
25h
W
=
Words:
Cycles:
1
1
W
=
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
ADDWF
REG, 0, 0
Before Instruction
W
=
17h
REG
=
0C2h
After Instruction
W
REG
=
=
0D9h
0C2h
Note:
All PIC18 instructions may take an optional label argument preceding the instruction mnemonic for use in
symbolic addressing. If a label is used, the instruction format then becomes: {label} instruction argument(s).
2004 Microchip Technology Inc.
Preliminary
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ADDWFC
ADD W and CARRY bit to f
ANDLW
AND literal with W
Syntax:
ADDWFC
f {,d {,a}}
Syntax:
ANDLW
k
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operands:
Operation:
Status Affected:
Encoding:
Description:
0 ≤ k ≤ 255
(W) .AND. k → W
N, Z
Operation:
(W) + (f) + (C) → dest
0000
1011
kkkk
kkkk
Status Affected:
Encoding:
N,OV, C, DC, Z
The contents of W are AND’ed with the
8-bit literal ‘k’. The result is placed in W.
0010
00da
ffff
ffff
Description:
Add W, the CARRY flag and data mem-
ory location ‘f’. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed in data memory location ‘f’.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
1
Cycles:
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read literal
‘k’
Process
Data
Write to W
Example:
ANDLW
05Fh
Before Instruction
W
=
A3h
03h
After Instruction
W
=
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
ADDWFC
REG, 0, 1
Before Instruction
CARRY bit =
1
02h
4Dh
REG
W
=
=
After Instruction
CARRY bit =
0
02h
50h
REG
W
=
=
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ANDWF
AND W with f
BC
Branch if Carry
Syntax:
ANDWF
f {,d {,a}}
Syntax:
BC
n
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operands:
Operation:
-128 ≤ n ≤ 127
if CARRY bit is ‘1’
(PC) + 2 + 2n → PC
Operation:
(W) .AND. (f) → dest
Status Affected:
Encoding:
None
Status Affected:
Encoding:
N, Z
1110
0010
nnnn
nnnn
0001
01da
ffff
ffff
Description:
If the CARRY bit is ‘1’, then the program
will branch.
Description:
The contents of W are AND’ed with
register ‘f’. If ‘d’ is ‘0’, the result is stored
in W. If ‘d’ is ‘1’, the result is stored back
in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Cycles:
1
1(2)
Q Cycle Activity:
If Jump:
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
Words:
1
1
Cycles:
No
No
No
No
operation
operation
operation
operation
Q Cycle Activity:
Q1
If No Jump:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Decode
Read literal
‘n’
Process
Data
No
operation
Example:
ANDWF
REG, 0, 0
Example:
HERE
BC
5
Before Instruction
Before Instruction
W
REG
=
=
17h
C2h
PC
=
address (HERE)
After Instruction
After Instruction
If CARRY
PC
If CARRY
PC
=
=
=
=
1;
address (HERE + 12)
0;
address (HERE + 2)
W
REG
=
=
02h
C2h
2004 Microchip Technology Inc.
Preliminary
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BCF
Bit Clear f
BN
Branch if Negative
Syntax:
BCF f, b {,a}
Syntax:
BN
n
Operands:
0 ≤ f ≤ 255
0 ≤ b ≤ 7
a ∈ [0,1]
Operands:
Operation:
-128 ≤ n ≤ 127
if NEGATIVE bit is ‘1’
(PC) + 2 + 2n → PC
Operation:
0 → f<b>
Status Affected:
Encoding:
None
Status Affected:
Encoding:
None
1110
0110
nnnn
nnnn
1001
bbba
ffff
ffff
Description:
If the NEGATIVE bit is ‘1’, then the
program will branch.
Description:
Bit ‘b’ in register ‘f’ is cleared.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Words:
Cycles:
1
1(2)
Q Cycle Activity:
If Jump:
Words:
Cycles:
1
1
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
Q Cycle Activity:
Q1
Q2
Q3
Q4
No
No
No
No
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
operation
operation
operation
operation
If No Jump:
Q1
Q2
Q3
Q4
Example:
BCF
FLAG_REG, 7, 0
C7h
47h
Decode
Read literal
‘n’
Process
Data
No
operation
Before Instruction
FLAG_REG =
After Instruction
FLAG_REG =
Example:
HERE
BN Jump
Before Instruction
PC
=
address (HERE)
After Instruction
If NEGATIVE
PC
If NEGATIVE
PC
=
=
=
=
1;
address (Jump)
0;
address (HERE + 2)
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BNC
Branch if Not Carry
BNN
Branch if Not Negative
Syntax:
BNC
n
Syntax:
BNN
n
Operands:
Operation:
-128 ≤ n ≤ 127
Operands:
Operation:
-128 ≤ n ≤ 127
if CARRY bit is ‘0’
(PC) + 2 + 2n → PC
if NEGATIVE bit is ‘0’
(PC) + 2 + 2n → PC
Status Affected:
Encoding:
None
Status Affected:
Encoding:
None
1110
0011
nnnn
nnnn
1110
0111
nnnn
nnnn
Description:
If the CARRY bit is ‘0’, then the program
will branch.
Description:
If the NEGATIVE bit is ‘0’, then the
program will branch.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Words:
Cycles:
1
Words:
Cycles:
1
1(2)
1(2)
Q Cycle Activity:
If Jump:
Q Cycle Activity:
If Jump:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
Decode
Read literal
‘n’
Process
Data
Write to PC
No
No
No
No
No
No
No
No
operation
operation
operation
operation
operation
operation
operation
operation
If No Jump:
Q1
If No Jump:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
Decode
Read literal
‘n’
Process
Data
No
operation
Example:
HERE
BNC Jump
Example:
HERE
BNN Jump
Before Instruction
Before Instruction
PC
=
address (HERE)
PC
=
address (HERE)
After Instruction
After Instruction
If CARRY
PC
If CARRY
PC
=
=
=
=
0;
If NEGATIVE
PC
If NEGATIVE
PC
=
=
=
=
0;
address (Jump)
address (Jump)
1;
1;
address (HERE + 2)
address (HERE + 2)
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BNOV
Branch if Not Overflow
BNZ
Branch if Not Zero
Syntax:
BNOV
n
Syntax:
BNZ
n
Operands:
Operation:
-128 ≤ n ≤ 127
Operands:
Operation:
-128 ≤ n ≤ 127
if OVERFLOW bit is ‘0’
(PC) + 2 + 2n → PC
if ZERO bit is ‘0’
(PC) + 2 + 2n → PC
Status Affected:
Encoding:
None
Status Affected:
Encoding:
None
1110
0101
nnnn
nnnn
1110
0001
nnnn
nnnn
Description:
If the OVERFLOW bit is ‘0’, then the
program will branch.
Description:
If the ZERO bit is ‘0’, then the program
will branch.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Words:
Cycles:
1
Words:
Cycles:
1
1(2)
1(2)
Q Cycle Activity:
If Jump:
Q Cycle Activity:
If Jump:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
Decode
Read literal
‘n’
Process
Data
Write to PC
No
No
No
No
No
No
No
No
operation
operation
operation
operation
operation
operation
operation
operation
If No Jump:
Q1
If No Jump:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
Decode
Read literal
‘n’
Process
Data
No
operation
Example:
HERE
BNOV Jump
Example:
HERE
BNZ Jump
Before Instruction
Before Instruction
PC
=
address (HERE)
PC
=
address (HERE)
After Instruction
After Instruction
If OVERFLOW =
PC
0;
If ZERO
PC
If ZERO
PC
=
=
=
=
0;
=
address (Jump)
address (Jump)
If OVERFLOW =
1;
1;
PC
=
address (HERE + 2)
address (HERE + 2)
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BRA
Unconditional Branch
BSF
Bit Set f
Syntax:
BRA
n
Syntax:
BSF f, b {,a}
Operands:
Operation:
-1024 ≤ n ≤ 1023
Operands:
0 ≤ f ≤ 255
0 ≤ b ≤ 7
a ∈ [0,1]
(PC) + 2 + 2n → PC
Status Affected: None
Operation:
1 → f<b>
Encoding:
1101
0nnn
nnnn
nnnn
Status Affected:
Encoding:
None
Description:
Add the 2’s complement number ‘2n’ to
the PC. Since the PC will have incre-
mented to fetch the next instruction, the
new address will be PC + 2 + 2n. This
instruction is a two-cycle instruction.
1000
bbba
ffff
ffff
Description:
Bit ‘b’ in register ‘f’ is set.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Cycles:
1
2
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
No
operation
No
operation
No
operation
No
operation
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Example:
HERE
BRA Jump
Q2
Q3
Q4
Before Instruction
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
PC
=
=
address (HERE)
address (Jump)
After Instruction
PC
Example:
BSF
FLAG_REG, 7, 1
0Ah
8Ah
Before Instruction
FLAG_REG
After Instruction
FLAG_REG
=
=
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BTFSC
Bit Test File, Skip if Clear
BTFSS
Bit Test File, Skip if Set
Syntax:
BTFSC f, b {,a}
Syntax:
BTFSS f, b {,a}
Operands:
0 ≤ f ≤ 255
0 ≤ b ≤ 7
a ∈ [0,1]
Operands:
0 ≤ f ≤ 255
0 ≤ b < 7
a ∈ [0,1]
Operation:
skip if (f<b>) = 0
Operation:
skip if (f<b>) = 1
Status Affected:
Encoding:
None
Status Affected:
Encoding:
None
1011
bbba
ffff
ffff
1010
bbba
ffff
ffff
Description:
If bit ‘b’ in register ‘f’ is ‘0’, then the next
instruction is skipped. If bit ‘b’ is ‘0’, then
the next instruction fetched during the
current instruction execution is discarded
and a NOPis executed instead, making
this a two-cycle instruction.
Description:
If bit ‘b’ in register ‘f’ is ‘1’, then the next
instruction is skipped. If bit ‘b’ is ‘1’, then
the next instruction fetched during the
current instruction execution is discarded
and a NOPis executed instead, making
this a two-cycle instruction.
If ‘a’ is ‘0’, the Access Bank is selected. If
‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’, the Access Bank is selected. If
‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates in
Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh).
See Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh).
See Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Cycles:
1
Words:
Cycles:
1
1(2)
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
No
operation
Decode
Read
register ‘f’
Process
Data
No
operation
If skip:
Q1
If skip:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
No
No
No
No
No
No
No
No
operation
operation
operation
operation
operation
operation
operation
operation
If skip and followed by 2-word instruction:
If skip and followed by 2-word instruction:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
No
No
No
No
No
No
No
No
operation
operation
operation
operation
operation
operation
operation
operation
No
No
No
No
No
No
No
No
operation
operation
operation
operation
operation
operation
operation
operation
Example:
HERE
FALSE
TRUE
BTFSC
:
:
FLAG, 1, 0
Example:
HERE
FALSE
TRUE
BTFSS
:
:
FLAG, 1, 0
Before Instruction
PC
Before Instruction
PC
=
address (HERE)
=
address (HERE)
After Instruction
After Instruction
If FLAG<1>
PC
If FLAG<1>
PC
=
=
=
=
0;
If FLAG<1>
PC
If FLAG<1>
PC
=
=
=
=
0;
address (TRUE)
1;
address (FALSE)
1;
address (FALSE)
address (TRUE)
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BTG
Bit Toggle f
BOV
Branch if Overflow
Syntax:
BTG f, b {,a}
Syntax:
BOV
n
Operands:
0 ≤ f ≤ 255
0 ≤ b < 7
a ∈ [0,1]
Operands:
Operation:
-128 ≤ n ≤ 127
if OVERFLOW bit is ‘1’
(PC) + 2 + 2n → PC
Operation:
(f<b>) → f<b>
Status Affected:
Encoding:
None
Status Affected:
Encoding:
None
1110
0100
nnnn
nnnn
0111
bbba
ffff
ffff
Description:
If the OVERFLOW bit is ‘1’, then the
program will branch.
Description:
Bit ‘b’ in data memory location ‘f’ is
inverted.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will have
incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Words:
Cycles:
1
1(2)
Q Cycle Activity:
If Jump:
Words:
Cycles:
1
1
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
Q Cycle Activity:
Q1
No
operation
No
operation
No
operation
No
operation
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
If No Jump:
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
Example:
BTG
PORTC, 4, 0
Before Instruction:
PORTC
After Instruction:
PORTC
=
0111 0101 [75h]
0110 0101 [65h]
Example:
HERE
BOV Jump
Before Instruction
=
PC
=
address (HERE)
After Instruction
If OVERFLOW =
PC
If OVERFLOW =
PC
1;
=
address (Jump)
0;
=
address (HERE + 2)
2004 Microchip Technology Inc.
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BZ
Branch if Zero
CALL
Subroutine Call
Syntax:
BZ
n
Syntax:
CALL k {,s}
Operands:
Operation:
-128 ≤ n ≤ 127
Operands:
0 ≤ k ≤ 1048575
s ∈ [0,1]
if ZERO bit is ‘1’
(PC) + 2 + 2n → PC
Operation:
(PC) + 4 → TOS,
k → PC<20:1>,
if s = 1
Status Affected:
Encoding:
None
1110
0000
nnnn
nnnn
(W) → WS,
(Status) → STATUSS,
(BSR) → BSRS
Description:
If the ZERO bit is ‘1’, then the program
will branch.
The 2’s complement number ‘2n’ is
added to the PC. Since the PC will
have incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is then a
two-cycle instruction.
Status Affected:
None
Encoding:
1st word (k<7:0>)
2nd word(k<19:8>)
1110
1111
110s
k kkk
kkkk
kkkk
7
0
8
k
kkk kkkk
19
Description:
Subroutine call of entire 2-Mbyte
memory range. First, return address
(PC + 4) is pushed onto the return
stack. If ‘s’ = 1, the W, Status and BSR
registers are also pushed into their
respective shadow registers, WS,
STATUSS and BSRS. If ‘s’ = 0, no
update occurs (default). Then, the
20-bit value ‘k’ is loaded into PC<20:1>.
CALLis a two-cycle instruction.
Words:
Cycles:
1
1(2)
Q Cycle Activity:
If Jump:
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to PC
No
operation
No
No
No
Words:
Cycles:
2
2
operation
operation
operation
If No Jump:
Q1
Q2
Q3
Q4
Q Cycle Activity:
Q1
Decode
Read literal
‘n’
Process
Data
No
operation
Q2
Q3
Q4
Decode
Read literal PUSH PC to Read literal
‘k’<7:0>,
stack
‘k’<19:8>,
Write to PC
Example:
HERE
BZ Jump
No
operation
No
operation
No
operation
No
operation
Before Instruction
PC
=
address (HERE)
After Instruction
If ZERO
PC
If ZERO
PC
=
=
=
=
1;
Example:
HERE
CALL THERE, 1
address (Jump)
Before Instruction
PC
After Instruction
0;
address (HERE + 2)
=
address (HERE)
PC
TOS
WS
BSRS
STATUSS=
=
address (THERE)
=
=
=
address (HERE + 4)
W
BSR
Status
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CLRF
Clear f
CLRWDT
Clear Watchdog Timer
Syntax:
CLRF f {,a}
Syntax:
CLRWDT
None
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operands:
Operation:
000h → WDT,
000h → WDT postscaler,
1 → TO,
Operation:
000h → f
1 → Z
1 → PD
Status Affected:
Encoding:
Z
Status Affected:
Encoding:
TO, PD
0110
101a
ffff
ffff
0000
0000
0000
0100
Description:
Clears the contents of the specified
register.
Description:
CLRWDTinstruction resets the
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
Watchdog Timer. It also resets the
postscaler of the WDT. Status bits, TO
and PD, are set.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
No
Process
Data
No
operation
operation
Words:
Cycles:
1
1
Example:
CLRWDT
Q Cycle Activity:
Q1
Before Instruction
Q2
Q3
Q4
WDT Counter
After Instruction
WDT Counter
WDT Postscaler
TO
=
?
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
=
=
=
=
00h
0
1
Example:
CLRF
FLAG_REG, 1
PD
1
Before Instruction
FLAG_REG
After Instruction
FLAG_REG
=
=
5Ah
00h
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 283
PIC18F2420/2520/4420/4520
CPFSEQ
Compare f with W, skip if f = W
COMF
Complement f
Syntax:
CPFSEQ f {,a}
Syntax:
COMF f {,d {,a}}
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(f) – (W),
skip if (f) = (W)
(unsigned comparison)
Operation:
(f) → dest
Status Affected:
Encoding:
N, Z
Status Affected:
Encoding:
None
0001
11da
ffff
ffff
0110
001a
ffff
ffff
Description:
The contents of register ‘f’ are
Description:
Compares the contents of data memory
location ‘f’ to the contents of W by
performing an unsigned subtraction.
If ‘f’ = W, then the fetched instruction is
discarded and a NOPis executed
instead, making this a two-cycle
instruction.
complemented. If ‘d’ is ‘0’, the result is
stored in W. If ‘d’ is ‘1’, the result is
stored back in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Words:
Cycles:
1
Q2
Q3
Q4
1(2)
Decode
Read
register ‘f’
Process
Data
Write to
destination
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Example:
COMF
REG, 0, 0
Q2
Q3
Q4
Before Instruction
Decode
Read
register ‘f’
Process
Data
No
operation
REG
=
13h
After Instruction
If skip:
REG
W
=
=
13h
ECh
Q1
No
Q2
No
Q3
No
Q4
No
operation
operation
operation
operation
If skip and followed by 2-word instruction:
Q1
No
Q2
No
Q3
No
Q4
No
operation
No
operation
No
operation
No
operation
No
operation
operation
operation
operation
Example:
HERE
CPFSEQ REG, 0
NEQUAL
EQUAL
:
:
Before Instruction
PC Address
=
HERE
W
REG
=
=
?
?
After Instruction
If REG
PC
=
=
W;
Address (EQUAL)
If REG
PC
≠
=
W;
Address (NEQUAL)
DS39631A-page 284
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
CPFSGT
Compare f with W, skip if f > W
CPFSLT
Compare f with W, skip if f < W
Syntax:
CPFSGT f {,a}
Syntax:
CPFSLT f {,a}
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operation:
(f) – (W),
skip if (f) > (W)
(unsigned comparison)
Operation:
(f) – (W),
skip if (f) < (W)
(unsigned comparison)
Status Affected:
Encoding:
None
Status Affected:
Encoding:
None
0110
010a
ffff
ffff
0110
000a
ffff
ffff
Description:
Compares the contents of data memory
location ‘f’ to the contents of the W by
performing an unsigned subtraction.
If the contents of ‘f’ are greater than the
contents of WREG, then the fetched
instruction is discarded and a NOPis
executed instead, making this a
Description:
Compares the contents of data memory
location ‘f’ to the contents of W by
performing an unsigned subtraction.
If the contents of ‘f’ are less than the
contents of W, then the fetched
instruction is discarded and a NOPis
executed instead, making this a
two-cycle instruction.
two-cycle instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
Words:
Cycles:
1
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Words:
Cycles:
1
Decode
Read
register ‘f’
Process
Data
No
operation
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
If skip:
Q1
Q2
Q3
Q4
Q Cycle Activity:
Q1
No
operation
No
operation
No
operation
No
operation
Q2
Q3
Q4
No
operation
Decode
Read
register ‘f’
Process
Data
If skip and followed by 2-word instruction:
If skip:
Q1
Q2
Q3
Q4
Q1
No
Q2
No
Q3
No
Q4
No
No
operation
No
operation
No
operation
No
operation
operation
operation
operation
operation
No
No
No
No
If skip and followed by 2-word instruction:
operation
operation
operation
operation
Q1
No
operation
No
Q2
No
operation
No
Q3
No
operation
No
Q4
No
operation
No
Example:
HERE
NLESS
LESS
CPFSLT REG, 1
:
:
operation
operation
operation
operation
Before Instruction
PC
W
=
=
Address (HERE)
Example:
HERE
NGREATER
GREATER
CPFSGT REG, 0
:
:
?
After Instruction
If REG
PC
If REG
PC
<
=
≥
=
W;
Before Instruction
Address (LESS)
W;
Address (NLESS)
PC
W
=
=
Address (HERE)
?
After Instruction
If REG
PC
>
=
W;
Address (GREATER)
If REG
PC
≤
=
W;
Address (NGREATER)
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 285
PIC18F2420/2520/4420/4520
DAW
Decimal Adjust W Register
DECF
Decrement f
Syntax:
DAW
None
Syntax:
DECF f {,d {,a}}
Operands:
Operation:
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
If [W<3:0> > 9] or [DC = 1] then
(W<3:0>) + 6 → W<3:0>;
else
Operation:
(f) – 1 → dest
(W<3:0>) → W<3:0>;
Status Affected:
Encoding:
C, DC, N, OV, Z
0000
01da
ffff
ffff
If [W<7:4> + DC > 9] or [C = 1] then
(W<7:4>) + 6 + DC → W<7:4> ;
else
Description:
Decrement register ‘f’. If ‘d’ is ‘0’, the
result is stored in W. If ‘d’ is ‘1’, the
result is stored back in register ‘f’
(default).
(W<7:4>) + DC → W<7:4>
Status Affected:
Encoding:
C
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
0000
0000
0000
0111
Description:
DAW adjusts the eight-bit value in W,
resulting from the earlier addition of two
variables (each in packed BCD format)
and produces a correct packed BCD
result.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Words:
Cycles:
1
1
Q2
Q3
Q4
Decode
Read
register W
Process
Data
Write
W
Q Cycle Activity:
Q1
Q2
Q3
Q4
Example1:
Decode
Read
register ‘f’
Process
Data
Write to
destination
DAW
Before Instruction
W
C
DC
=
=
=
A5h
0
0
Example:
DECF
CNT,
1, 0
Before Instruction
After Instruction
CNT
Z
After Instruction
=
01h
0
=
W
=
05h
1
0
C
DC
=
=
CNT
Z
=
=
00h
1
Example 2:
Before Instruction
W
=
CEh
C
DC
=
=
0
0
After Instruction
W
=
34h
C
DC
=
=
1
0
DS39631A-page 286
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
DECFSZ
Decrement f, skip if 0
DCFSNZ
Decrement f, skip if not 0
Syntax:
DECFSZ f {,d {,a}}
Syntax:
DCFSNZ f {,d {,a}}
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(f) – 1 → dest,
Operation:
(f) – 1 → dest,
skip if result = 0
skip if result ≠ 0
Status Affected:
Encoding:
None
Status Affected:
Encoding:
None
0010
11da
ffff
ffff
0100
11da
ffff
ffff
Description:
The contents of register ‘f’ are
Description:
The contents of register ‘f’ are
decremented. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If the result is ‘0’, the next instruction,
which is already fetched, is discarded
and a NOPis executed instead, making
it a two-cycle instruction.
decremented. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If the result is not ‘0’, the next
instruction, which is already fetched, is
discarded and a NOPis executed
instead, making it a two-cycle
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Cycles:
1
Words:
Cycles:
1
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Decode
Read
Process
Data
Write to
destination
register ‘f’
If skip:
Q1
If skip:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
No
No
No
No
operation
operation
operation
operation
No
No
No
No
operation
operation
operation
operation
If skip and followed by 2-word instruction:
If skip and followed by 2-word instruction:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
No
No
No
No
operation
operation
operation
operation
No
No
No
No
operation
operation
operation
operation
No
No
No
No
operation
operation
operation
operation
No
No
No
No
operation
operation
operation
operation
Example:
HERE
DECFSZ
GOTO
CNT, 1, 1
LOOP
Example:
HERE
ZERO
NZERO
DCFSNZ TEMP, 1, 0
:
:
CONTINUE
Before Instruction
PC
After Instruction
Before Instruction
TEMP
After Instruction
=
Address (HERE)
=
?
CNT
=
CNT - 1
0;
If CNT
=
=
≠
=
TEMP
If TEMP
PC
If TEMP
PC
=
=
=
≠
=
TEMP – 1,
0;
Address (ZERO)
0;
Address (NZERO)
PC
Address (CONTINUE)
0;
If CNT
PC
Address (HERE + 2)
2004 Microchip Technology Inc.
Preliminary
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PIC18F2420/2520/4420/4520
GOTO
Unconditional Branch
INCF
Increment f
Syntax:
GOTO
k
Syntax:
INCF f {,d {,a}}
Operands:
Operation:
Status Affected:
0 ≤ k ≤ 1048575
k → PC<20:1>
None
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(f) + 1 → dest
Encoding:
1st word (k<7:0>)
2nd word(k<19:8>)
Status Affected:
Encoding:
C, DC, N, OV, Z
1110
1111
1111
kkk
k kkk
kkkk
kkkk
kkkk
7
0
8
k
0010
10da
ffff
ffff
19
Description:
GOTOallows an unconditional branch
anywhere within entire
2-Mbyte memory range. The 20-bit
value ‘k’ is loaded into PC<20:1>.
GOTOis always a two-cycle
instruction.
Description:
The contents of register ‘f’ are
incremented. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Cycles:
2
2
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read literal
‘k’<7:0>,
No
operation
Read literal
‘k’<19:8>,
Write to PC
Words:
Cycles:
1
1
No
operation
No
No
No
operation
operation
operation
Q Cycle Activity:
Q1
Example:
GOTO THERE
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
After Instruction
PC
=
Address (THERE)
Example:
INCF
CNT, 1, 0
Before Instruction
CNT
Z
=
FFh
0
=
=
=
C
?
DC
?
After Instruction
CNT
Z
=
00h
1
=
=
=
C
1
DC
1
DS39631A-page 288
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
INFSNZ
Increment f, skip if not 0
INCFSZ
Increment f, skip if 0
Syntax:
INFSNZ f {,d {,a}}
Syntax:
INCFSZ f {,d {,a}}
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(f) + 1 → dest,
skip if result ≠ 0
Operation:
(f) + 1 → dest,
skip if result = 0
Status Affected:
Encoding:
None
Status Affected:
Encoding:
None
0100
10da
ffff
ffff
0011
11da
ffff
ffff
Description:
The contents of register ‘f’ are
Description:
The contents of register ‘f’ are
incremented. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If the result is not ‘0’, the next
instruction, which is already fetched, is
discarded and a NOPis executed
instead, making it a two-cycle
incremented. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If the result is ‘0’, the next instruction,
which is already fetched, is discarded
and a NOPis executed instead, making
it a two-cycle instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Cycles:
1
Words:
Cycles:
1
1(2)
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Decode
Read
register ‘f’
Process
Data
Write to
destination
If skip:
Q1
If skip:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
No
No
No
No
No
No
No
No
operation
operation
operation
operation
operation
operation
operation
operation
If skip and followed by 2-word instruction:
If skip and followed by 2-word instruction:
Q1
Q2
Q3
Q4
Q1
Q2
Q3
Q4
No
No
No
No
No
No
No
No
operation
operation
operation
operation
operation
operation
operation
operation
No
No
No
No
No
No
No
No
operation
operation
operation
operation
operation
operation
operation
operation
Example:
HERE
NZERO
ZERO
INCFSZ
:
:
CNT, 1, 0
Example:
HERE
ZERO
NZERO
INFSNZ REG, 1, 0
Before Instruction
PC
After Instruction
Before Instruction
PC
After Instruction
=
Address (HERE)
=
Address (HERE)
REG
If REG
PC
If REG
PC
=
REG + 1
0;
Address (NZERO)
0;
Address (ZERO)
CNT
If CNT
PC
If CNT
PC
=
CNT + 1
≠
=
=
=
=
=
≠
=
0;
Address (ZERO)
0;
Address (NZERO)
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 289
PIC18F2420/2520/4420/4520
IORLW
Inclusive OR literal with W
IORWF
Inclusive OR W with f
Syntax:
IORLW
k
Syntax:
IORWF f {,d {,a}}
Operands:
Operation:
Status Affected:
Encoding:
Description:
0 ≤ k ≤ 255
(W) .OR. k → W
N, Z
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(W) .OR. (f) → dest
0000
1001
kkkk
kkkk
Status Affected:
Encoding:
N, Z
The contents of W are ORed with the
eight-bit literal ‘k’. The result is placed in
W.
0001
00da
ffff
ffff
Description:
Inclusive OR W with register ‘f’. If ‘d’ is
‘0’, the result is placed in W. If ‘d’ is ‘1’,
the result is placed back in register ‘f’
(default).
Words:
Cycles:
1
1
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to W
Example:
IORLW
35h
Before Instruction
W
=
9Ah
BFh
After Instruction
Words:
Cycles:
1
1
W
=
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
IORWF RESULT, 0, 1
Before Instruction
RESULT =
13h
91h
W
=
After Instruction
RESULT =
13h
93h
W
=
DS39631A-page 290
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
LFSR
Load FSR
MOVF
Move f
Syntax:
LFSR f, k
Syntax:
MOVF f {,d {,a}}
Operands:
0 ≤ f ≤ 2
0 ≤ k ≤ 4095
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
k → FSRf
Operation:
f → dest
Status Affected:
Encoding:
None
Status Affected:
Encoding:
N, Z
1110
1111
1110
0000
00ff
k kkk
k kkk
11
kkkk
0101
00da
ffff
ffff
7
Description:
The 12-bit literal ‘k’ is loaded into the
File Select Register pointed to by ‘f’.
Description:
The contents of register ‘f’ are moved to
a destination dependent upon the
status of ‘d’. If ‘d’ is ‘0’, the result is
placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
Location ‘f’ can be anywhere in the
256-byte bank.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Cycles:
2
2
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read literal
‘k’ MSB
Process
Data
Write
literal ‘k’
MSB to
FSRfH
Decode
Read literal
‘k’ LSB
Process
Data
Write literal
‘k’ to FSRfL
Example:
LFSR 2, 3ABh
After Instruction
Words:
Cycles:
1
1
FSR2H
FSR2L
=
=
03h
ABh
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write W
Example:
MOVF
REG, 0, 0
Before Instruction
REG
W
=
=
22h
FFh
After Instruction
REG
W
=
=
22h
22h
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MOVFF
Move f to f
MOVLB
Move literal to low nibble in BSR
Syntax:
MOVFF f ,f
Syntax:
MOVLW k
s
d
Operands:
0 ≤ f ≤ 4095
Operands:
Operation:
Status Affected:
Encoding:
Description:
0 ≤ k ≤ 255
k → BSR
None
s
0 ≤ f ≤ 4095
d
Operation:
(f ) → f
s
d
Status Affected:
None
0000
0001
kkkk
kkkk
Encoding:
1st word (source)
2nd word (destin.)
The eight-bit literal ‘k’ is loaded into the
Bank Select Register (BSR). The value
of BSR<7:4> always remains ‘0’,
1100
1111
ffff
ffff
ffff
ffff
ffffs
ffffd
Description:
The contents of source register ‘f ’ are
regardless of the value of k :k .
s
7 4
moved to destination register ‘f ’.
d
Words:
Cycles:
1
1
Location of source ‘f ’ can be anywhere
s
in the 4096-byte data space (000h to
FFFh) and location of destination ‘f ’
can also be anywhere from 000h to
FFFh.
Either source or destination can be W
(a useful special situation).
d
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write literal
‘k’ to BSR
MOVFFis particularly useful for
transferring a data memory location to a
peripheral register (such as the transmit
buffer or an I/O port).
The MOVFFinstruction cannot use the
PCL, TOSU, TOSH or TOSL as the
destination register.
Example:
MOVLB
5
Before Instruction
BSR Register =
After Instruction
BSR Register =
02h
05h
Words:
Cycles:
2
2 (3)
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
(src)
Process
Data
No
operation
Decode
No
operation
No
operation
Write
register ‘f’
(dest)
No dummy
read
Example:
MOVFF
REG1, REG2
Before Instruction
REG1
REG2
=
=
33h
11h
After Instruction
REG1
REG2
=
=
33h
33h
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MOVLW
Move literal to W
MOVWF
Move W to f
Syntax:
MOVLW
k
Syntax:
MOVWF f {,a}
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
0 ≤ k ≤ 255
k → W
None
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operation:
(W) → f
Status Affected:
Encoding:
None
0000
1110
kkkk
kkkk
0110
111a
ffff
ffff
The eight-bit literal ‘k’ is loaded into W.
Description:
Move data from W to register ‘f’.
Location ‘f’ can be anywhere in the
256-byte bank.
1
1
Cycles:
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to W
Example:
MOVLW
5Ah
After Instruction
W
=
5Ah
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Example:
MOVWF
REG, 0
Before Instruction
W
REG
=
=
4Fh
FFh
After Instruction
W
REG
=
=
4Fh
4Fh
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MULLW
Multiply literal with W
MULWF
Multiply W with f
Syntax:
MULLW
k
Syntax:
MULWF f {,a}
Operands:
Operation:
Status Affected:
Encoding:
Description:
0 ≤ k ≤ 255
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
(W) x k → PRODH:PRODL
Operation:
(W) x (f) → PRODH:PRODL
None
Status Affected:
Encoding:
None
0000
1101
kkkk
kkkk
0000
001a
ffff
ffff
An unsigned multiplication is carried
out between the contents of W and the
8-bit literal ‘k’. The 16-bit result is
placed in the PRODH:PRODL register
pair. PRODH contains the high byte.
W is unchanged.
None of the Status flags are affected.
Note that neither overflow nor carry is
possible in this operation. A zero result
is possible but not detected.
Description:
An unsigned multiplication is carried
out between the contents of W and the
register file location ‘f’. The 16-bit
result is stored in the PRODH:PRODL
register pair. PRODH contains the
high byte. Both W and ‘f’ are
unchanged.
None of the Status flags are affected.
Note that neither overflow nor carry is
possible in this operation. A zero
result is possible but not detected.
If ‘a’ is ‘0’, the Access Bank is
selected. If ‘a’ is ‘1’, the BSR is used
to select the GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction
operates in Indexed Literal Offset
Addressing mode whenever
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write
registers
PRODH:
PRODL
f ≤ 95 (5Fh). See Section 24.2.3
“Byte-Oriented and Bit-Oriented
Instructions in Indexed Literal Offset
Mode” for details.
Example:
MULLW
0C4h
Before Instruction
Words:
Cycles:
1
1
W
PRODH
PRODL
=
=
=
E2h
?
?
Q Cycle Activity:
Q1
After Instruction
Q2
Q3
Q4
W
PRODH
PRODL
=
=
=
E2h
ADh
08h
Decode
Read
register ‘f’
Process
Data
Write
registers
PRODH:
PRODL
Example:
MULWF
REG, 1
Before Instruction
W
REG
PRODH
PRODL
=
C4h
B5h
?
?
=
=
=
After Instruction
W
=
C4h
REG
PRODH
PRODL
=
=
=
B5h
8Ah
94h
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NEGF
Negate f
NOP
No Operation
Syntax:
NEGF f {,a}
Syntax:
NOP
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operands:
Operation:
Status Affected:
Encoding:
None
No operation
None
Operation:
( f ) + 1 → f
Status Affected:
Encoding:
N, OV, C, DC, Z
0000
1111
0000
xxxx
0000
xxxx
0000
xxxx
0110
110a
ffff
ffff
Description:
Location ‘f’ is negated using two’s
complement. The result is placed in the
data memory location ‘f’.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Description:
Words:
No operation.
1
1
Cycles:
Q Cycle Activity:
Q1
Q2
Q3
No
Q4
Decode
No
operation
No
operation
operation
Example:
None.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Example:
NEGF
REG, 1
Before Instruction
REG
After Instruction
REG
=
0011 1010 [3Ah]
1100 0110 [C6h]
=
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POP
Pop Top of Return Stack
PUSH
Push Top of Return Stack
Syntax:
POP
Syntax:
PUSH
Operands:
Operation:
Status Affected:
Encoding:
Description:
None
Operands:
Operation:
Status Affected:
Encoding:
Description:
None
(TOS) → bit bucket
(PC + 2) → TOS
None
None
0000
0000
0000
0110
0000
0000
0000
0101
The TOS value is pulled off the return
stack and is discarded. The TOS value
then becomes the previous value that
was pushed onto the return stack.
This instruction is provided to enable
the user to properly manage the return
stack to incorporate a software stack.
The PC + 2 is pushed onto the top of
the return stack. The previous TOS
value is pushed down on the stack.
This instruction allows implementing a
software stack by modifying TOS and
then pushing it onto the return stack.
Words:
Cycles:
1
1
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
Decode
PUSH
No
No
Decode
No
operation
POP TOS
value
No
operation
PC + 2 onto
return stack
operation
operation
Example:
POP
Example:
PUSH
GOTO
NEW
Before Instruction
Before Instruction
TOS
Stack (1 level down)
TOS
PC
=
=
345Ah
0124h
=
=
0031A2h
014332h
After Instruction
After Instruction
PC
=
=
=
0126h
0126h
345Ah
TOS
TOS
PC
=
=
014332h
NEW
Stack (1 level down)
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RCALL
Relative Call
RESET
Reset
Syntax:
RCALL
n
Syntax:
RESET
None
Operands:
Operation:
-1024 ≤ n ≤ 1023
Operands:
Operation:
(PC) + 2 → TOS,
(PC) + 2 + 2n → PC
Reset all registers and flags that are
affected by a MCLR Reset.
Status Affected:
Encoding:
None
Status Affected:
Encoding:
All
1101
1nnn
nnnn
nnnn
0000
0000
1111
1111
Description:
Subroutine call with a jump up to 1K
from the current location. First, return
address (PC + 2) is pushed onto the
stack. Then, add the 2’s complement
number ‘2n’ to the PC. Since the PC will
have incremented to fetch the next
instruction, the new address will be
PC + 2 + 2n. This instruction is a
two-cycle instruction.
Description:
This instruction provides a way to
execute a MCLR Reset in software.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Start
No
No
Reset
operation
operation
Words:
Cycles:
1
2
Example:
RESET
Q Cycle Activity:
Q1
After Instruction
Registers =
Q2
Q3
Q4
Reset Value
Reset Value
Flags*
=
Decode
Read literal
‘n’
Process
Data
Write to PC
PUSH PCto
stack
No
No
No
No
operation
operation
operation
operation
Example:
HERE
RCALL Jump
Before Instruction
PC
After Instruction
PC
TOS =
=
Address (HERE)
=
Address (Jump)
Address (HERE + 2)
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RETFIE
Return from Interrupt
RETLW
Return literal to W
Syntax:
RETFIE {s}
Syntax:
RETLW k
Operands:
Operation:
s ∈ [0,1]
Operands:
Operation:
0 ≤ k ≤ 255
(TOS) → PC,
k → W,
1 → GIE/GIEH or PEIE/GIEL,
if s = 1
(TOS) → PC,
PCLATU, PCLATH are unchanged
(WS) → W,
(STATUSS) → Status,
(BSRS) → BSR,
Status Affected:
Encoding:
None
0000
1100
kkkk
kkkk
PCLATU, PCLATH are unchanged.
Description:
W is loaded with the eight-bit literal ‘k’.
The program counter is loaded from the
top of the stack (the return address).
The high address latch (PCLATH)
remains unchanged.
Status Affected:
Encoding:
GIE/GIEH, PEIE/GIEL.
0000
0000
0001
000s
Description:
Return from interrupt. Stack is popped
and Top-of-Stack (TOS) is loaded into
the PC. Interrupts are enabled by
setting either the high or low priority
global interrupt enable bit. If ‘s’ = 1, the
contents of the shadow registers, WS,
STATUSS and BSRS, are loaded into
their corresponding registers, W,
Words:
Cycles:
1
2
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
POP PC
from stack,
Write to W
Status and BSR. If ‘s’ = 0, no update of
these registers occurs (default).
No
operation
No
operation
No
operation
No
operation
Words:
Cycles:
1
2
Q Cycle Activity:
Q1
Example:
Q2
Q3
Q4
CALL TABLE ; W contains table
; offset value
Decode
No
operation
No
operation
POP PC
from stack
; W now has
; table value
Set GIEH or
GIEL
:
No
operation
No
operation
No
operation
No
operation
TABLE
ADDWF PCL ; W = offset
RETLW k0
RETLW k1
; Begin table
;
Example:
RETFIE
1
:
:
After Interrupt
PC
W
=
=
=
=
=
TOS
WS
RETLW kn
; End of table
BSR
Status
GIE/GIEH, PEIE/GIEL
BSRS
STATUSS
1
Before Instruction
W
=
07h
After Instruction
W
=
value of kn
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RETURN
Return from Subroutine
RLCF
Rotate Left f through Carry
Syntax:
RETURN {s}
Syntax:
RLCF f {,d {,a}}
Operands:
Operation:
s ∈ [0,1]
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
(TOS) → PC,
if s = 1
(WS) → W,
Operation:
(f<n>) → dest<n + 1>,
(f<7>) → C,
(C) → dest<0>
(STATUSS) → Status,
(BSRS) → BSR,
PCLATU, PCLATH are unchanged
Status Affected:
Encoding:
C, N, Z
Status Affected:
Encoding:
None
0011
01da
ffff
ffff
0000
0000
0001
001s
Description:
The contents of register ‘f’ are rotated
one bit to the left through the CARRY
flag. If ‘d’ is ‘0’, the result is placed in
W. If ‘d’ is ‘1’, the result is stored back
in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is
selected. If ‘a’ is ‘1’, the BSR is used to
select the GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction
operates in Indexed Literal Offset
Addressing mode whenever
Description:
Return from subroutine. The stack is
popped and the top of the stack (TOS)
is loaded into the program counter. If
‘s’= 1, the contents of the shadow
registers, WS, STATUSS and BSRS,
are loaded into their corresponding
registers, W, Status and BSR. If
‘s’ = 0, no update of these registers
occurs (default).
Words:
Cycles:
1
2
f ≤ 95 (5Fh). See Section 24.2.3
“Byte-Oriented and Bit-Oriented
Instructions in Indexed Literal Offset
Mode” for details.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
No
operation
Process
Data
POP PC
from stack
register f
C
No
No
No
No
Words:
Cycles:
1
1
operation
operation
operation
operation
Q Cycle Activity:
Q1
Example:
RETURN
Q2
Q3
Q4
After Instruction:
PC = TOS
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
RLCF
REG, 0, 0
Before Instruction
REG
C
=
=
1110 0110
0
After Instruction
REG
=
1110 0110
W
C
=
=
1100 1100
1
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RLNCF
Rotate Left f (No Carry)
RRCF
Rotate Right f through Carry
Syntax:
RLNCF f {,d {,a}}
Syntax:
RRCF f {,d {,a}}
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(f<n>) → dest<n + 1>,
(f<7>) → dest<0>
Operation:
(f<n>) → dest<n – 1>,
(f<0>) → C,
(C) → dest<7>
Status Affected:
Encoding:
N, Z
Status Affected:
Encoding:
C, N, Z
0100
01da
ffff
ffff
0011
00da
ffff
ffff
Description:
The contents of register ‘f’ are rotated
one bit to the left. If ‘d’ is ‘0’, the result
is placed in W. If ‘d’ is ‘1’, the result is
stored back in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Description:
The contents of register ‘f’ are rotated
one bit to the right through the CARRY
flag. If ‘d’ is ‘0’, the result is placed in W.
If ‘d’ is ‘1’, the result is placed back in
register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
register f
register f
C
Words:
Cycles:
1
1
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q Cycle Activity:
Q1
Decode
Read
register ‘f’
Process
Data
Write to
destination
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
RLNCF
REG, 1, 0
Before Instruction
REG
After Instruction
Example:
RRCF
REG, 0, 0
=
1010 1011
0101 0111
Before Instruction
REG
=
REG
C
=
=
1110 0110
0
After Instruction
REG
=
1110 0110
W
C
=
=
0111 0011
0
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RRNCF
Rotate Right f (No Carry)
SETF
Set f
Syntax:
RRNCF f {,d {,a}}
Syntax:
SETF f {,a}
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operation:
FFh → f
Operation:
(f<n>) → dest<n – 1>,
(f<0>) → dest<7>
Status Affected:
Encoding:
None
0110
100a
ffff
ffff
Status Affected:
Encoding:
N, Z
Description:
The contents of the specified register
are set to FFh.
0100
00da
ffff
ffff
Description:
The contents of register ‘f’ are rotated
one bit to the right. If ‘d’ is ‘0’, the result
is placed in W. If ‘d’ is ‘1’, the result is
placed back in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank will be
selected, overriding the BSR value. If ‘a’
is ‘1’, then the bank will be selected as
per the BSR value (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
register f
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Words:
Cycles:
1
1
Example:
SETF
REG, 1
Q Cycle Activity:
Q1
Before Instruction
REG
After Instruction
REG
=
=
5Ah
FFh
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example 1:
RRNCF
REG, 1, 0
Before Instruction
REG
After Instruction
REG
=
1101 0111
1110 1011
RRNCF REG, 0, 0
=
Example 2:
Before Instruction
W
REG
=
=
?
1101 0111
After Instruction
W
REG
=
=
1110 1011
1101 0111
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SLEEP
Enter Sleep mode
SUBFWB
Subtract f from W with borrow
Syntax:
SLEEP
None
Syntax:
SUBFWB f {,d {,a}}
Operands:
Operation:
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
00h → WDT,
0 → WDT postscaler,
1 → TO,
Operation:
(W) – (f) – (C) → dest
0 → PD
Status Affected:
Encoding:
N, OV, C, DC, Z
Status Affected:
Encoding:
TO, PD
0101
01da
ffff
ffff
0000
0000
0000
0011
Description:
Subtract register ‘f’ and CARRY flag
(borrow) from W (2’s complement
method). If ‘d’ is ‘0’, the result is stored
in W. If ‘d’ is ‘1’, the result is stored in
register ‘f’ (default).
Description:
The Power-down status bit (PD) is
cleared. The Time-out status bit (TO)
is set. Watchdog Timer and its
postscaler are cleared.
The processor is put into Sleep mode
with the oscillator stopped.
If ‘a’ is ‘0’, the Access Bank is
selected. If ‘a’ is ‘1’, the BSR is used
to select the GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction
operates in Indexed Literal Offset
Addressing mode whenever
f ≤ 95 (5Fh). See Section 24.2.3
“Byte-Oriented and Bit-Oriented
Instructions in Indexed Literal Offset
Mode” for details.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
No
operation
Process
Data
Go to
Sleep
Example:
SLEEP
Words:
Cycles:
1
1
Before Instruction
TO
PD
=
=
?
?
Q Cycle Activity:
Q1
Q2
Q3
Q4
After Instruction
Decode
Read
register ‘f’
Process
Data
Write to
destination
TO
PD
=
=
1 †
0
Example 1:
SUBFWB
REG, 1, 0
†
If WDT causes wake-up, this bit is cleared.
Before Instruction
REG
W
C
=
=
=
3
2
1
After Instruction
REG
W
C
=
FF
2
=
=
=
=
0
Z
0
1
N
; result is negative
Example 2:
SUBFWB
REG, 0, 0
Before Instruction
REG
W
=
=
=
2
5
1
C
After Instruction
REG
W
C
=
2
3
1
0
=
=
=
=
Z
N
0
; result is positive
Example 3:
Before Instruction
SUBFWB
REG, 1, 0
REG
W
=
=
=
1
2
0
C
After Instruction
REG
W
C
=
0
2
1
1
0
=
=
=
=
Z
; result is zero
N
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SUBLW
Subtract W from literal
SUBWF
Subtract W from f
Syntax:
SUBLW
k
Syntax:
SUBWF f {,d {,a}}
Operands:
Operation:
Status Affected:
Encoding:
Description
0 ≤ k ≤ 255
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
k – (W) → W
N, OV, C, DC, Z
Operation:
(f) – (W) → dest
0000
1000
kkkk
kkkk
Status Affected:
Encoding:
N, OV, C, DC, Z
W is subtracted from the eight-bit
literal ‘k’. The result is placed in W.
0101
11da
ffff
ffff
Description:
Subtract W from register ‘f’ (2’s
complement method). If ‘d’ is ‘0’, the
result is stored in W. If ‘d’ is ‘1’, the
result is stored back in register ‘f’
(default).
Words:
1
1
Cycles:
Q Cycle Activity:
Q1
Q2
Q3
Q4
If ‘a’ is ‘0’, the Access Bank is
selected. If ‘a’ is ‘1’, the BSR is used
to select the GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction
operates in Indexed Literal Offset
Addressing mode whenever
f ≤ 95 (5Fh). See Section 24.2.3
“Byte-Oriented and Bit-Oriented
Instructions in Indexed Literal Offset
Mode” for details.
Decode
Read
literal ‘k’
Process
Data
Write to W
Example 1:
SUBLW 02h
Before Instruction
W
C
=
=
01h
?
After Instruction
W
C
Z
=
01h
=
=
=
1
0
0
; result is positive
N
Words:
Cycles:
1
1
Example 2:
SUBLW 02h
Before Instruction
Q Cycle Activity:
Q1
W
C
=
=
02h
?
Q2
Q3
Q4
After Instruction
Decode
Read
register ‘f’
Process
Data
Write to
destination
W
C
Z
=
00h
=
=
=
1
1
0
; result is zero
N
Example 1:
SUBWF
REG, 1, 0
Before Instruction
Example 3:
Before Instruction
SUBLW 02h
REG
W
C
=
3
2
?
=
=
W
C
=
=
03h
?
After Instruction
After Instruction
REG
W
C
=
1
2
1
0
0
W
C
Z
=
FFh ; (2’s complement)
=
=
=
=
=
=
=
0
0
1
; result is negative
; result is positive
Z
N
N
Example 2:
SUBWF
REG, 0, 0
Before Instruction
REG
W
=
=
=
2
2
?
C
After Instruction
REG
W
C
=
2
0
1
1
0
=
=
=
=
; result is zero
Z
N
Example 3:
Before Instruction
SUBWF
REG, 1, 0
REG
W
=
=
=
1
2
?
C
After Instruction
REG
W
C
=
FFh ;(2’s complement)
2
0
0
1
=
=
=
=
; result is negative
Z
N
2004 Microchip Technology Inc.
Preliminary
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SUBWFB
Subtract W from f with Borrow
SWAPF
Swap f
Syntax:
SUBWFB f {,d {,a}}
Syntax:
SWAPF f {,d {,a}}
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(f) – (W) – (C) → dest
Operation:
(f<3:0>) → dest<7:4>,
(f<7:4>) → dest<3:0>
Status Affected:
Encoding:
N, OV, C, DC, Z
0101
10da
ffff
ffff
Status Affected:
Encoding:
None
Description:
Subtract W and the CARRY flag
0011
10da
ffff
ffff
(borrow) from register ‘f’ (2’s comple-
ment method). If ‘d’ is ‘0’, the result is
stored in W. If ‘d’ is ‘1’, the result is
stored back in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Description:
The upper and lower nibbles of register
‘f’ are exchanged. If ‘d’ is ‘0’, the result
is placed in W. If ‘d’ is ‘1’, the result is
placed in register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
Cycles:
1
1
Words:
1
1
Cycles:
Q Cycle Activity:
Q1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example 1:
SUBWFB REG, 1, 0
Before Instruction
REG
W
=
=
=
19h
0Dh
1
(0001 1001)
(0000 1101)
Example:
SWAPF
REG, 1, 0
C
Before Instruction
After Instruction
REG
=
53h
35h
REG
W
C
=
0Ch
0Dh
1
(0000 1011)
(0000 1101)
After Instruction
=
=
=
=
REG
=
Z
0
N
0
; result is positive
Example 2:
Before Instruction
SUBWFB REG, 0, 0
REG
W
=
=
=
1Bh
1Ah
0
(0001 1011)
(0001 1010)
C
After Instruction
REG
W
C
=
1Bh
00h
1
(0001 1011)
=
=
=
=
Z
1
; result is zero
N
0
Example 3:
SUBWFB REG, 1, 0
Before Instruction
REG
W
=
=
=
03h
0Eh
1
(0000 0011)
(0000 1101)
C
After Instruction
REG
=
F5h
(1111 0100)
; [2’s comp]
W
C
Z
=
=
=
=
0Eh
0
0
1
(0000 1101)
N
; result is negative
DS39631A-page 304
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2004 Microchip Technology Inc.
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TBLRD
Table Read
TBLRD
Table Read (Continued)
Syntax:
TBLRD ( *; *+; *-; +*)
None
Example1:
TBLRD *+ ;
Operands:
Operation:
Before Instruction
TABLAT
TBLPTR
MEMORY (00A356h)
=
=
=
55h
00A356h
34h
if TBLRD *,
(Prog Mem (TBLPTR)) → TABLAT;
TBLPTR – No Change;
if TBLRD *+,
(Prog Mem (TBLPTR)) → TABLAT;
(TBLPTR) + 1 → TBLPTR;
if TBLRD *-,
(Prog Mem (TBLPTR)) → TABLAT;
(TBLPTR) – 1 → TBLPTR;
if TBLRD +*,
(TBLPTR) + 1 → TBLPTR;
(Prog Mem (TBLPTR)) → TABLAT;
After Instruction
TABLAT
TBLPTR
=
=
34h
00A357h
Example2:
TBLRD +* ;
Before Instruction
TABLAT
TBLPTR
MEMORY (01A357h)
MEMORY (01A358h)
After Instruction
=
=
=
=
AAh
01A357h
12h
34h
TABLAT
TBLPTR
=
=
34h
01A358h
Status Affected: None
Encoding:
0000
0000
0000
10nn
nn=0 *
=1 *+
=2 *-
=3 +*
Description:
This instruction is used to read the contents
of Program Memory (P.M.). To address the
program memory, a pointer called Table
Pointer (TBLPTR) is used.
The TBLPTR (a 21-bit pointer) points to
each byte in the program memory. TBLPTR
has a 2-Mbyte address range.
TBLPTR[0] = 0: LeastSignificantByte
of Program Memory
Word
TBLPTR[0] = 1: Most Significant Byte
of Program Memory
Word
The TBLRDinstruction can modify the value
of TBLPTR as follows:
•
•
•
•
no change
post-increment
post-decrement
pre-increment
Words:
Cycles:
1
2
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
No
No
No
operation
operation
operation
No
No operation
No
No operation
operation (Read Program operation (Write TABLAT)
Memory)
2004 Microchip Technology Inc.
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PIC18F2420/2520/4420/4520
TBLWT
Table Write
TBLWT
Table Write (Continued)
Syntax:
TBLWT ( *; *+; *-; +*)
None
Example1:
TBLWT *+;
Operands:
Operation:
Before Instruction
if TBLWT*,
TABLAT
TBLPTR
HOLDING REGISTER
(00A356h)
=
=
55h
00A356h
(TABLAT) → Holding Register;
TBLPTR – No Change;
if TBLWT*+,
(TABLAT) → Holding Register;
(TBLPTR) + 1 → TBLPTR;
if TBLWT*-,
(TABLAT) → Holding Register;
(TBLPTR) – 1 → TBLPTR;
if TBLWT+*,
(TBLPTR) + 1 → TBLPTR;
(TABLAT) → Holding Register;
=
FFh
After Instructions (table write completion)
TABLAT
TBLPTR
HOLDING REGISTER
(00A356h)
=
=
55h
00A357h
=
55h
Example 2:
TBLWT +*;
Before Instruction
TABLAT
TBLPTR
HOLDING REGISTER
(01389Ah)
HOLDING REGISTER
(01389Bh)
=
=
34h
01389Ah
Status Affected: None
=
FFh
Encoding:
0000
0000
0000
11nn
nn=0 *
=1 *+
=2 *-
=3 +*
=
FFh
After Instruction (table write completion)
TABLAT
TBLPTR
HOLDING REGISTER
(01389Ah)
HOLDING REGISTER
(01389Bh)
=
=
34h
01389Bh
Description:
This instruction uses the 3 LSBs of
TBLPTR to determine which of the
8 holding registers the TABLAT is written
to. The holding registers are used to
program the contents of Program
Memory (P.M.). (Refer to Section 6.0
“Flash Program Memory” for additional
details on programming Flash memory.)
The TBLPTR (a 21-bit pointer) points to
each byte in the program memory.
TBLPTR has a 2-MByte address range.
The LSb of the TBLPTR selects which
byte of the program memory location to
access.
=
=
FFh
34h
TBLPTR[0] = 0: Least Significant
Byte of Program
Memory Word
TBLPTR[0] = 1: Most Significant
Byte of Program
Memory Word
The TBLWT instruction can modify the
value of TBLPTR as follows:
•
•
•
•
no change
post-increment
post-decrement
pre-increment
Words:
1
2
Cycles:
Q Cycle Activity:
Q1
Q2
No
Q3
No
Q4
No
Decode
operation operation operation
No
No No No
operation operation operation operation
(Read
TABLAT)
(Write to
Holding
Register )
DS39631A-page 306
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TSTFSZ
Test f, skip if 0
XORLW
Exclusive OR literal with W
Syntax:
TSTFSZ f {,a}
Syntax:
XORLW k
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operands:
Operation:
Status Affected:
Encoding:
Description:
0 ≤ k ≤ 255
(W) .XOR. k → W
N, Z
Operation:
skip if f = 0
Status Affected:
Encoding:
None
0000
1010
kkkk
kkkk
0110
011a
ffff
ffff
The contents of W are XORed with
the 8-bit literal ‘k’. The result is placed
in W.
Description:
If ‘f’ = 0, the next instruction fetched
during the current instruction execution
is discarded and a NOPis executed,
making this a two-cycle instruction.
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
1
Cycles:
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to W
Example:
XORLW
0AFh
Before Instruction
W
=
B5h
1Ah
Words:
Cycles:
1
After Instruction
1(2)
W
=
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
No
operation
If skip:
Q1
Q2
Q3
Q4
No
No
No
No
operation
operation
operation
operation
If skip and followed by 2-word instruction:
Q1
Q2
Q3
Q4
No
No
No
No
operation
operation
operation
operation
No
No
No
No
operation
operation
operation
operation
Example:
HERE
NZERO
ZERO
TSTFSZ CNT, 1
:
:
Before Instruction
PC
=
Address (HERE)
After Instruction
If CNT
PC
If CNT
PC
=
=
≠
=
00h,
Address (ZERO)
00h,
Address (NZERO)
2004 Microchip Technology Inc.
Preliminary
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XORWF
Exclusive OR W with f
Syntax:
XORWF f {,d {,a}}
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(W) .XOR. (f) → dest
Status Affected:
Encoding:
N, Z
0001
10da
ffff
ffff
Description:
Exclusive OR the contents of W with
register ‘f’. If ‘d’ is ‘0’, the result is stored
in W. If ‘d’ is ‘1’, the result is stored back
in the register ‘f’ (default).
If ‘a’ is ‘0’, the Access Bank is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f ≤ 95 (5Fh). See
Section 24.2.3 “Byte-Oriented and
Bit-Oriented Instructions in Indexed
Literal Offset Mode” for details.
Words:
1
1
Cycles:
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
XORWF
REG, 1, 0
Before Instruction
REG
W
=
=
AFh
B5h
After Instruction
REG
W
=
=
1Ah
B5h
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A summary of the instructions in the extended instruc-
tion set is provided in Table 24-3. Detailed descriptions
are provided in Section 24.2.2 “Extended Instruction
Set”. The opcode field descriptions in Table 24-1
(page 268) apply to both the standard and extended
PIC18 instruction sets.
24.2 Extended Instruction Set
In addition to the standard 75 instructions of the PIC18
instruction set, PIC18F2420/2520/4420/4520 devices
also provide an optional extension to the core CPU
functionality. The added features include eight addi-
tional instructions that augment indirect and indexed
addressing operations and the implementation of
Indexed Literal Offset Addressing mode for many of the
standard PIC18 instructions.
Note:
The instruction set extension and the
Indexed Literal Offset Addressing mode
were designed for optimizing applications
written in C; the user may likely never use
these instructions directly in assembler.
The syntax for these commands is pro-
vided as a reference for users who may be
reviewing code that has been generated
by a compiler.
The additional features of the extended instruction set
are disabled by default. To enable them, users must set
the XINST configuration bit.
The instructions in the extended set can all be
classified as literal operations, which either manipulate
the File Select Registers, or use them for indexed
addressing. Two of the instructions, ADDFSR and
SUBFSR, each have an additional special instantiation
for using FSR2. These versions (ADDULNK and
SUBULNK) allow for automatic return after execution.
24.2.1
EXTENDED INSTRUCTION SYNTAX
Most of the extended instructions use indexed argu-
ments, using one of the File Select Registers and some
offset to specify a source or destination register. When
an argument for an instruction serves as part of
indexed addressing, it is enclosed in square brackets
(“[ ]”). This is done to indicate that the argument is used
as an index or offset. MPASM™ Assembler will flag an
error if it determines that an index or offset value is not
bracketed.
The extended instructions are specifically implemented
to optimize re-entrant program code (that is, code that
is recursive or that uses a software stack) written in
high-level languages, particularly C. Among other
things, they allow users working in high-level
languages to perform certain operations on data
structures more efficiently. These include:
When the extended instruction set is enabled, brackets
are also used to indicate index arguments in byte-
oriented and bit-oriented instructions. This is in addition
to other changes in their syntax. For more details, see
Section 24.2.3.1 “Extended Instruction Syntax with
Standard PIC18 Commands”.
• dynamic allocation and deallocation of software
stack space when entering and leaving
subroutines
• function pointer invocation
• software stack pointer manipulation
• manipulation of variables located in a software
stack
Note:
In the past, square brackets have been
used to denote optional arguments in the
PIC18 and earlier instruction sets. In this
text and going forward, optional
arguments are denoted by braces (“{ }”).
TABLE 24-3: EXTENSIONS TO THE PIC18 INSTRUCTION SET
16-Bit Instruction Word
MSb LSb
Mnemonic,
Operands
Status
Affected
Description
Cycles
ADDFSR
ADDULNK
CALLW
f, k
k
Add literal to FSR
Add literal to FSR2 and return
Call subroutine using WREG
1
2
2
2
1110 1000 ffkk kkkk
1110 1000 11kk kkkk
0000 0000 0001 0100
1110 1011 0zzz zzzz
1111 ffff ffff ffff
1110 1011 1zzz zzzz
1111 xxxx xzzz zzzz
1110 1010 kkkk kkkk
None
None
None
None
MOVSF
zs, fd Move zs (source) to 1st word
fd (destination) 2nd word
zs, zd Move zs (source) to 1st word
MOVSS
PUSHL
2
1
None
None
zd (destination)
Store literal at FSR2,
decrement FSR2
2nd word
k
SUBFSR
SUBULNK
f, k
k
Subtract literal from FSR
Subtract literal from FSR2 and
return
1
2
1110 1001 ffkk kkkk
1110 1001 11kk kkkk
None
None
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 309
PIC18F2420/2520/4420/4520
24.2.2
EXTENDED INSTRUCTION SET
ADDFSR
Add Literal to FSR
ADDULNK
Add Literal to FSR2 and Return
Syntax:
ADDFSR f, k
Syntax:
ADDULNK k
Operands:
0 ≤ k ≤ 63
f ∈ [ 0, 1, 2 ]
FSR(f) + k → FSR(f)
None
Operands:
Operation:
0 ≤ k ≤ 63
FSR2 + k → FSR2,
(TOS) → PC
None
Operation:
Status Affected:
Encoding:
Status Affected:
Encoding:
1110
1000
ffkk
kkkk
1110
1000
11kk
kkkk
Description:
The 6-bit literal ‘k’ is added to the
contents of the FSR specified by ‘f’.
Description:
The 6-bit literal ‘k’ is added to the
contents of FSR2. A RETURNis then
executed by loading the PC with the
TOS.
Words:
1
1
Cycles:
The instruction takes two cycles to
execute; a NOPis performed during
the second cycle.
This may be thought of as a special
case of the ADDFSRinstruction,
where f = 3 (binary ‘11’); it operates
only on FSR2.
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to
FSR
ADDFSR 2, 23h
Example:
Words:
Cycles:
1
2
Before Instruction
FSR2
After Instruction
FSR2
=
03FFh
0422h
Q Cycle Activity:
Q1
=
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to
FSR
No
No
No
No
Operation
Operation
Operation
Operation
ADDULNK 23h
Example:
Before Instruction
FSR2
PC
=
=
03FFh
0100h
After Instruction
FSR2
PC
=
=
0422h
(TOS)
Note:
All PIC18 instructions may take an optional label argument preceding the instruction mnemonic for use in
symbolic addressing. If a label is used, the instruction syntax then becomes: {label} instruction argument(s).
DS39631A-page 310
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2004 Microchip Technology Inc.
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CALLW
Subroutine Call Using WREG
MOVSF
Move Indexed to f
Syntax:
CALLW
None
Syntax:
MOVSF [z ], f
s
d
Operands:
Operation:
Operands:
0 ≤ z ≤ 127
s
0 ≤ f ≤ 4095
d
(PC + 2) → TOS,
(W) → PCL,
Operation:
((FSR2) + z ) → f
s
d
(PCLATH) → PCH,
(PCLATU) → PCU
Status Affected:
None
Encoding:
1st word (source)
2nd word (destin.)
Status Affected:
Encoding:
None
1110
1111
1011
ffff
0zzz
ffff
zzzz
ffff
s
0000
0000
0001
0100
d
Description
First, the return address (PC + 2) is
pushed onto the return stack. Next, the
contents of W are written to PCL; the
existing value is discarded. Then, the
contents of PCLATH and PCLATU are
latched into PCH and PCU,
respectively. The second cycle is
executed as a NOPinstruction while the
new next instruction is fetched.
Description:
The contents of the source register are
moved to destination register ‘f ’. The
d
actual address of the source register is
determined by adding the 7-bit literal
offset ‘z ’ in the first word to the value of
s
FSR2. The address of the destination
register is specified by the 12-bit literal
‘f ’ in the second word. Both addresses
d
can be anywhere in the 4096-byte data
space (000h to FFFh).
The MOVSFinstruction cannot use the
PCL, TOSU, TOSH or TOSL as the
destination register.
If the resultant source address points to
an indirect addressing register, the
value returned will be 00h.
Unlike CALL, there is no option to
update W, Status or BSR.
Words:
Cycles:
1
2
Q Cycle Activity:
Q1
Q2
Q3
Q4
Words:
Cycles:
2
2
Decode
Read
WREG
PUSH PC to
stack
No
operation
No
operation
No
operation
No
operation
No
operation
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Determine
Determine
Read
source addr source addr source reg
Example:
HERE
CALLW
Decode
No
operation
No
operation
Write
register ‘f’
(dest)
Before Instruction
PC
=
address (HERE)
PCLATH =
PCLATU =
10h
00h
06h
No dummy
read
W
=
After Instruction
PC
TOS
=
=
001006h
address (HERE + 2)
Example:
MOVSF
[05h], REG2
PCLATH =
PCLATU =
10h
00h
06h
Before Instruction
FSR2
=
80h
33h
W
=
Contents
of 85h
REG2
=
=
11h
After Instruction
FSR2
=
80h
Contents
of 85h
REG2
=
=
33h
33h
2004 Microchip Technology Inc.
Preliminary
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MOVSS
Move Indexed to Indexed
PUSHL
Store Literal at FSR2, Decrement FSR2
Syntax:
MOVSS [z ], [z ]
Syntax:
PUSHL k
s
d
Operands:
0 ≤ z ≤ 127
s
Operands:
Operation:
0 ≤ k ≤ 255
0 ≤ z ≤ 127
d
k → (FSR2),
FSR2 – 1 → FSR2
Operation:
((FSR2) + z ) → ((FSR2) + z )
s d
Status Affected:
None
Status Affected: None
Encoding:
1st word (source)
2nd word (dest.)
Encoding:
1111
1010
kkkk
kkkk
1110
1111
1011
xxxx
1zzz
xzzz
zzzz
zzzz
s
d
Description:
The 8-bit literal ‘k’ is written to the data
memory address specified by FSR2. FSR2
is decremented by 1 after the operation.
This instruction allows users to push values
onto a software stack.
Description
The contents of the source register are
moved to the destination register. The
addresses of the source and destination
registers are determined by adding the
7-bit literal offsets ‘z ’ or ‘z ’,
Words:
Cycles:
1
1
s
d
respectively, to the value of FSR2. Both
registers can be located anywhere in
the 4096-byte data memory space
(000h to FFFh).
Q Cycle Activity:
Q1
Q2
Q3
Q4
The MOVSSinstruction cannot use the
PCL, TOSU, TOSH or TOSL as the
destination register.
Decode
Read ‘k’
Process
data
Write to
destination
If the resultant source address points to
an indirect addressing register, the
value returned will be 00h. If the
resultant destination address points to
an indirect addressing register, the
instruction will execute as a NOP.
Example:
PUSHL 08h
Before Instruction
FSR2H:FSR2L
Memory (01ECh)
=
=
01ECh
00h
Words:
2
2
After Instruction
FSR2H:FSR2L
Memory (01ECh)
=
=
01EBh
08h
Cycles:
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Determine
Determine
Read
source addr source addr source reg
Decode
Determine
dest addr
Determine
dest addr
Write
to dest reg
Example:
MOVSS [05h], [06h]
Before Instruction
FSR2
=
=
=
80h
33h
11h
Contents
of 85h
Contents
of 86h
After Instruction
FSR2
=
=
=
80h
33h
33h
Contents
of 85h
Contents
of 86h
DS39631A-page 312
Preliminary
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SUBFSR
Subtract Literal from FSR
SUBULNK
Subtract Literal from FSR2 and Return
Syntax:
SUBFSR f, k
0 ≤ k ≤ 63
f ∈ [ 0, 1, 2 ]
FSR(f) – k → FSRf
None
Syntax:
SUBULNK k
Operands:
Operands:
Operation:
0 ≤ k ≤ 63
FSR2 – k → FSR2
(TOS) → PC
Operation:
Status Affected:
Encoding:
Status Affected: None
1110
1001
ffkk
kkkk
Encoding:
1110
1001
11kk
kkkk
Description:
The 6-bit literal ‘k’ is subtracted from
the contents of the FSR specified by
‘f’.
Description:
The 6-bit literal ‘k’ is subtracted from the
contents of the FSR2. A RETURNis then
executed by loading the PC with the TOS.
The instruction takes two cycles to
execute; a NOPis performed during the
second cycle.
This may be thought of as a special case of
the SUBFSRinstruction, where f = 3 (binary
‘11’); it operates only on FSR2.
Words:
1
1
Cycles:
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Words:
1
2
Cycles:
Q Cycle Activity:
Q1
Example:
SUBFSR 2, 23h
03FFh
Q2
Q3
Q4
Before Instruction
FSR2
After Instruction
FSR2
Decode
Read
register ‘f’
Process
Data
Write to
destination
=
No
Operation
No
Operation
No
Operation
No
Operation
=
03DCh
Example:
SUBULNK 23h
Before Instruction
FSR2
PC
=
=
03FFh
0100h
After Instruction
FSR2
PC
=
=
03DCh
(TOS)
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 313
PIC18F2420/2520/4420/4520
24.2.3
BYTE-ORIENTED AND
BIT-ORIENTED INSTRUCTIONS IN
INDEXED LITERAL OFFSET MODE
24.2.3.1
Extended Instruction Syntax with
Standard PIC18 Commands
When the extended instruction set is enabled, the file
register argument, ‘f’, in the standard byte-oriented and
bit-oriented commands is replaced with the literal offset
value, ‘k’. As already noted, this occurs only when ‘f’ is
less than or equal to 5Fh. When an offset value is used,
it must be indicated by square brackets (“[ ]”). As with
the extended instructions, the use of brackets indicates
to the compiler that the value is to be interpreted as an
index or an offset. Omitting the brackets, or using a
value greater than 5Fh within brackets, will generate an
error in the MPASM Assembler.
Note: Enabling the PIC18 instruction set
extension may cause legacy applications
to behave erratically or fail entirely.
In addition to eight new commands in the extended set,
enabling the extended instruction set also enables
Indexed Literal Offset Addressing mode (Section 5.5.1
“Indexed Addressing with Literal Offset”). This has
a significant impact on the way that many commands of
the standard PIC18 instruction set are interpreted.
When the extended set is disabled, addresses embed-
ded in opcodes are treated as literal memory locations:
either as a location in the Access Bank (‘a’ = 0), or in a
GPR bank designated by the BSR (‘a’ = 1). When the
extended instruction set is enabled and ‘a’ = 0, how-
ever, a file register argument of 5Fh or less is
interpreted as an offset from the pointer value in FSR2
and not as a literal address. For practical purposes, this
means that all instructions that use the Access RAM bit
as an argument – that is, all byte-oriented and bit-
oriented instructions, or almost half of the core PIC18
instructions – may behave differently when the
extended instruction set is enabled.
If the index argument is properly bracketed for Indexed
Literal Offset Addressing, the Access RAM argument is
never specified; it will automatically be assumed to be
‘0’. This is in contrast to standard operation (extended
instruction set disabled) when ‘a’ is set on the basis of
the target address. Declaring the Access RAM bit in
this mode will also generate an error in the MPASM
Assembler.
The destination argument, ‘d’, functions as before.
In the latest versions of the MPASM assembler,
language support for the extended instruction set must
be explicitly invoked. This is done with either the
command line option, /y, or the PE directive in the
source listing.
When the content of FSR2 is 00h, the boundaries of the
Access RAM are essentially remapped to their original
values. This may be useful in creating backward
compatible code. If this technique is used, it may be
necessary to save the value of FSR2 and restore it
when moving back and forth between C and assembly
routines in order to preserve the stack pointer. Users
must also keep in mind the syntax requirements of the
extended instruction set (see Section 24.2.3.1
“Extended Instruction Syntax with Standard PIC18
Commands”).
24.2.4
CONSIDERATIONS WHEN
ENABLING THE EXTENDED
INSTRUCTION SET
It is important to note that the extensions to the instruc-
tion set may not be beneficial to all users. In particular,
users who are not writing code that uses a software
stack may not benefit from using the extensions to the
instruction set.
Although the Indexed Literal Offset Addressing mode
can be very useful for dynamic stack and pointer
manipulation, it can also be very annoying if a simple
arithmetic operation is carried out on the wrong
register. Users who are accustomed to the PIC18 pro-
gramming must keep in mind that, when the extended
instruction set is enabled, register addresses of 5Fh or
less are used for Indexed Literal Offset Addressing.
Additionally, the Indexed Literal Offset Addressing
mode may create issues with legacy applications
written to the PIC18 assembler. This is because
instructions in the legacy code may attempt to address
registers in the Access Bank below 5Fh. Since these
addresses are interpreted as literal offsets to FSR2
when the instruction set extension is enabled, the
application may read or write to the wrong data
addresses.
Representative examples of typical byte-oriented and
bit-oriented instructions in the Indexed Literal Offset
Addressing mode are provided on the following page to
show how execution is affected. The operand condi-
tions shown in the examples are applicable to all
instructions of these types.
When porting an application to the PIC18F2420/2520/
4420/4520, it is very important to consider the type of
code. A large, re-entrant application that is written in ‘C’
and would benefit from efficient compilation will do well
when using the instruction set extensions. Legacy
applications that heavily use the Access Bank will most
likely not benefit from using the extended instruction
set.
DS39631A-page 314
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ADD W to Indexed
(Indexed Literal Offset mode)
Bit Set Indexed
BSF
ADDWF
(Indexed Literal Offset mode)
Syntax:
ADDWF
[k] {,d}
Syntax:
BSF [k], b
Operands:
0 ≤ k ≤ 95
d ∈ [0,1]
Operands:
0 ≤ f ≤ 95
0 ≤ b ≤ 7
Operation:
(W) + ((FSR2) + k) → dest
Operation:
1 → ((FSR2) + k)<b>
Status Affected:
Encoding:
N, OV, C, DC, Z
Status Affected:
Encoding:
None
0010
01d0
kkkk
kkkk
1000
bbb0
kkkk
kkkk
Description:
The contents of W are added to the
contents of the register indicated by
FSR2, offset by the value ‘k’.
If ‘d’ is ‘0’, the result is stored in W. If ‘d’
is ‘1’, the result is stored back in
register ‘f’ (default).
Description:
Bit ‘b’ of the register indicated by FSR2,
offset by the value ‘k’, is set.
Words:
1
1
Cycles:
Q Cycle Activity:
Q1
Words:
Cycles:
1
1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Q Cycle Activity:
Q1
Q2
Q3
Q4
Example:
BSF
[FLAG_OFST], 7
Decode
Read ‘k’
Process
Data
Write to
destination
Before Instruction
FLAG_OFST
FSR2
Contents
of 0A0Ah
=
=
0Ah
0A00h
Example:
ADDWF
[OFST], 0
=
55h
D5h
Before Instruction
After Instruction
W
OFST
FSR2
=
=
=
17h
2Ch
0A00h
Contents
of 0A0Ah
=
Contents
of 0A2Ch
=
20h
After Instruction
W
=
=
37h
20h
Set Indexed
(Indexed Literal Offset mode)
Contents
of 0A2Ch
SETF
Syntax:
SETF [k]
Operands:
Operation:
Status Affected:
Encoding:
Description:
0 ≤ k ≤ 95
FFh → ((FSR2) + k)
None
0110
1000
kkkk
kkkk
The contents of the register indicated by
FSR2, offset by ‘k’, are set to FFh.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read ‘k’
Process
Data
Write
register
Example:
SETF
[OFST]
2Ch
Before Instruction
OFST
=
=
FSR2
0A00h
Contents
of 0A2Ch
=
00h
After Instruction
Contents
of 0A2Ch
=
FFh
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 315
PIC18F2420/2520/4420/4520
To develop software for the extended instruction set,
the user must enable support for the instructions and
the Indexed Addressing mode in their language tool(s).
Depending on the environment being used, this may be
done in several ways:
24.2.5
SPECIAL CONSIDERATIONS WITH
MICROCHIP MPLAB® IDE TOOLS
The latest versions of Microchip’s software tools have
been designed to fully support the extended instruction
set of the PIC18F2420/2520/4420/4520 family of
devices. This includes the MPLAB C18 C compiler,
MPASM assembly language and MPLAB Integrated
Development Environment (IDE).
• A menu option, or dialog box within the
environment, that allows the user to configure the
language tool and its settings for the project
• A command line option
When selecting
a
target device for software
• A directive in the source code
development, MPLAB IDE will automatically set default
configuration bits for that device. The default setting for
the XINST configuration bit is ‘0’, disabling the
extended instruction set and Indexed Literal Offset
Addressing mode. For proper execution of applications
developed to take advantage of the extended
instruction set, XINST must be set during
programming.
These options vary between different compilers,
assemblers and development environments. Users are
encouraged to review the documentation accompany-
ing their development systems for the appropriate
information.
DS39631A-page 316
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25.1 MPLAB Integrated Development
Environment Software
25.0 DEVELOPMENT SUPPORT
The PICmicro® microcontrollers are supported with a
full range of hardware and software development tools:
The MPLAB IDE software brings an ease of software
development previously unseen in the 8/16-bit micro-
controller market. The MPLAB IDE is a Windows®
based application that contains:
• Integrated Development Environment
- MPLAB® IDE Software
• Assemblers/Compilers/Linkers
- MPASMTM Assembler
• An interface to debugging tools
- simulator
- MPLAB C17 and MPLAB C18 C Compilers
- MPLINKTM Object Linker/
MPLIBTM Object Librarian
- programmer (sold separately)
- emulator (sold separately)
- in-circuit debugger (sold separately)
• A full-featured editor with color coded context
• A multiple project manager
- MPLAB C30 C Compiler
- MPLAB ASM30 Assembler/Linker/Library
• Simulators
• Customizable data windows with direct edit of
contents
- MPLAB SIM Software Simulator
- MPLAB dsPIC30 Software Simulator
• Emulators
• High-level source code debugging
• Mouse over variable inspection
• Extensive on-line help
- MPLAB ICE 2000 In-Circuit Emulator
- MPLAB ICE 4000 In-Circuit Emulator
• In-Circuit Debugger
The MPLAB IDE allows you to:
• Edit your source files (either assembly or C)
- MPLAB ICD 2
• One touch assemble (or compile) and download
to PICmicro emulator and simulator tools
(automatically updates all project information)
• Device Programmers
- PRO MATE® II Universal Device Programmer
- PICSTART® Plus Development Programmer
- MPLAB PM3 Device Programmer
• Low-Cost Demonstration Boards
- PICDEMTM 1 Demonstration Board
- PICDEM.netTM Demonstration Board
- PICDEM 2 Plus Demonstration Board
- PICDEM 3 Demonstration Board
- PICDEM 4 Demonstration Board
- PICDEM 17 Demonstration Board
- PICDEM 18R Demonstration Board
- PICDEM LIN Demonstration Board
- PICDEM USB Demonstration Board
• Evaluation Kits
• Debug using:
- source files (assembly or C)
- mixed assembly and C
- machine code
MPLAB IDE supports multiple debugging tools in a
single development paradigm, from the cost effective
simulators, through low-cost in-circuit debuggers, to
full-featured emulators. This eliminates the learning
curve when upgrading to tools with increasing flexibility
and power.
25.2 MPASM Assembler
The MPASM assembler is a full-featured, universal
macro assembler for all PICmicro MCUs.
®
- KEELOQ Evaluation and Programming Tools
- PICDEM MSC
- microID® Developer Kits
- CAN
The MPASM assembler generates relocatable object
files for the MPLINK object linker, Intel® standard HEX
files, MAP files to detail memory usage and symbol ref-
erence, absolute LST files that contain source lines and
generated machine code and COFF files for
debugging.
- PowerSmart® Developer Kits
- Analog
The MPASM assembler features include:
• Integration into MPLAB IDE projects
• User defined macros to streamline assembly code
• Conditional assembly for multi-purpose source
files
• Directives that allow complete control over the
assembly process
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 317
PIC18F2420/2520/4420/4520
25.3 MPLAB C17 and MPLAB C18
C Compilers
25.6 MPLAB ASM30 Assembler, Linker
and Librarian
The MPLAB C17 and MPLAB C18 Code Development
MPLAB ASM30 assembler produces relocatable
machine code from symbolic assembly language for
dsPIC30F devices. MPLAB C30 compiler uses the
assembler to produce it’s object file. The assembler
generates relocatable object files that can then be
archived or linked with other relocatable object files and
archives to create an executable file. Notable features
of the assembler include:
Systems are complete ANSI
C
compilers for
Microchip’s PIC17CXXX and PIC18CXXX family of
microcontrollers. These compilers provide powerful
integration capabilities, superior code optimization and
ease of use not found with other compilers.
For easy source level debugging, the compilers provide
symbol information that is optimized to the MPLAB IDE
debugger.
• Support for the entire dsPIC30F instruction set
• Support for fixed-point and floating-point data
• Command line interface
25.4 MPLINK Object Linker/
MPLIB Object Librarian
• Rich directive set
The MPLINK object linker combines relocatable
objects created by the MPASM assembler and the
MPLAB C17 and MPLAB C18 C compilers. It can link
relocatable objects from precompiled libraries, using
directives from a linker script.
• Flexible macro language
• MPLAB IDE compatibility
25.7 MPLAB SIM Software Simulator
The MPLAB SIM software simulator allows code devel-
opment in a PC hosted environment by simulating the
PICmicro series microcontrollers on an instruction
level. On any given instruction, the data areas can be
examined or modified and stimuli can be applied from
a file, or user defined key press, to any pin. The execu-
tion can be performed in Single-Step, Execute Until
Break or Trace mode.
The MPLIB object librarian manages the creation and
modification of library files of precompiled code. When
a routine from a library is called from a source file, only
the modules that contain that routine will be linked in
with the application. This allows large libraries to be
used efficiently in many different applications.
The object linker/library features include:
• Efficient linking of single libraries instead of many
smaller files
The MPLAB SIM simulator fully supports symbolic
debugging using the MPLAB C17 and MPLAB C18
C Compilers, as well as the MPASM assembler. The
software simulator offers the flexibility to develop and
debug code outside of the laboratory environment,
making it an excellent, economical software
development tool.
• Enhanced code maintainability by grouping
related modules together
• Flexible creation of libraries with easy module
listing, replacement, deletion and extraction
25.5 MPLAB C30 C Compiler
25.8 MPLAB SIM30 Software Simulator
The MPLAB C30 C compiler is a full-featured, ANSI
compliant, optimizing compiler that translates standard
ANSI C programs into dsPIC30F assembly language
source. The compiler also supports many command
line options and language extensions to take full
advantage of the dsPIC30F device hardware capabili-
ties and afford fine control of the compiler code
generator.
The MPLAB SIM30 software simulator allows code
development in a PC hosted environment by simulating
the dsPIC30F series microcontrollers on an instruction
level. On any given instruction, the data areas can be
examined or modified and stimuli can be applied from
a file, or user defined key press, to any of the pins.
The MPLAB SIM30 simulator fully supports symbolic
debugging using the MPLAB C30 C Compiler and
MPLAB ASM30 assembler. The simulator runs in either
a Command Line mode for automated tasks, or from
MPLAB IDE. This high-speed simulator is designed to
debug, analyze and optimize time intensive DSP
routines.
MPLAB C30 is distributed with a complete ANSI C
standard library. All library functions have been vali-
dated and conform to the ANSI C library standard. The
library includes functions for string manipulation,
dynamic memory allocation, data conversion, time-
keeping and math functions (trigonometric, exponential
and hyperbolic). The compiler provides symbolic
information for high-level source debugging with the
MPLAB IDE.
DS39631A-page 318
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25.9 MPLAB ICE 2000
High-Performance Universal
In-Circuit Emulator
25.11 MPLAB ICD 2 In-Circuit Debugger
Microchip’s In-Circuit Debugger, MPLAB ICD 2, is a
powerful, low-cost, run-time development tool,
connecting to the host PC via an RS-232 or high-speed
The MPLAB ICE 2000 universal in-circuit emulator is
intended to provide the product development engineer
with a complete microcontroller design tool set for
PICmicro microcontrollers. Software control of the
MPLAB ICE 2000 in-circuit emulator is advanced by
the MPLAB Integrated Development Environment,
which allows editing, building, downloading and source
debugging from a single environment.
USB interface. This tool is based on the Flash
PICmicro MCUs and can be used to develop for these
and other PICmicro microcontrollers. The MPLAB
ICD 2 utilizes the in-circuit debugging capability built
into the Flash devices. This feature, along with
Microchip’s In-Circuit Serial ProgrammingTM (ICSPTM
)
protocol, offers cost effective in-circuit Flash debugging
from the graphical user interface of the MPLAB
Integrated Development Environment. This enables a
designer to develop and debug source code by setting
breakpoints, single-stepping and watching variables,
CPU status and peripheral registers. Running at full
speed enables testing hardware and applications in
real-time. MPLAB ICD 2 also serves as a development
programmer for selected PICmicro devices.
The MPLAB ICE 2000 is a full-featured emulator sys-
tem with enhanced trace, trigger and data monitoring
features. Interchangeable processor modules allow the
system to be easily reconfigured for emulation of differ-
ent processors. The universal architecture of the
MPLAB ICE in-circuit emulator allows expansion to
support new PICmicro microcontrollers.
The MPLAB ICE 2000 in-circuit emulator system has
been designed as a real-time emulation system with
advanced features that are typically found on more
expensive development tools. The PC platform and
Microsoft® Windows 32-bit operating system were
chosen to best make these features available in a
simple, unified application.
25.12 PRO MATE II Universal Device
Programmer
The PRO MATE II is a universal, CE compliant device
programmer with programmable voltage verification at
VDDMIN and VDDMAX for maximum reliability. It features
an LCD display for instructions and error messages
and a modular detachable socket assembly to support
various package types. In Stand-Alone mode, the
PRO MATE II device programmer can read, verify and
program PICmicro devices without a PC connection. It
can also set code protection in this mode.
25.10 MPLAB ICE 4000
High-Performance Universal
In-Circuit Emulator
The MPLAB ICE 4000 universal in-circuit emulator is
intended to provide the product development engineer
with a complete microcontroller design tool set for high-
end PICmicro microcontrollers. Software control of the
MPLAB ICE in-circuit emulator is provided by the
MPLAB Integrated Development Environment, which
allows editing, building, downloading and source
debugging from a single environment.
25.13 MPLAB PM3 Device Programmer
The MPLAB PM3 is a universal, CE compliant device
programmer with programmable voltage verification at
VDDMIN and VDDMAX for maximum reliability. It features
a large LCD display (128 x 64) for menus and error
messages and a modular detachable socket assembly
to support various package types. The ICSP™ cable
assembly is included as a standard item. In Stand-
Alone mode, the MPLAB PM3 device programmer can
read, verify and program PICmicro devices without a
PC connection. It can also set code protection in this
mode. MPLAB PM3 connects to the host PC via an RS-
232 or USB cable. MPLAB PM3 has high-speed com-
munications and optimized algorithms for quick pro-
gramming of large memory devices and incorporates
an SD/MMC card for file storage and secure data appli-
cations.
The MPLAB ICD 4000 is a premium emulator system,
providing the features of MPLAB ICE 2000, but with
increased emulation memory and high-speed perfor-
mance for dsPIC30F and PIC18XXXX devices. Its
advanced emulator features include complex triggering
and timing, up to 2 Mb of emulation memory and the
ability to view variables in real-time.
The MPLAB ICE 4000 in-circuit emulator system has
been designed as a real-time emulation system with
advanced features that are typically found on more
expensive development tools. The PC platform and
Microsoft Windows 32-bit operating system were
chosen to best make these features available in a
simple, unified application.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 319
PIC18F2420/2520/4420/4520
25.14 PICSTART Plus Development
Programmer
25.17 PICDEM 2 Plus
Demonstration Board
The PICSTART Plus development programmer is an
easy-to-use, low-cost, prototype programmer. It con-
nects to the PC via a COM (RS-232) port. MPLAB
Integrated Development Environment software makes
using the programmer simple and efficient. The
PICSTART Plus development programmer supports
most PICmicro devices up to 40 pins. Larger pin count
devices, such as the PIC16C92X and PIC17C76X,
may be supported with an adapter socket. The
PICSTART Plus development programmer is CE
compliant.
The PICDEM 2 Plus demonstration board supports
many 18, 28 and 40-pin microcontrollers, including
PIC16F87X and PIC18FXX2 devices. All the neces-
sary hardware and software is included to run the dem-
onstration programs. The sample microcontrollers
provided with the PICDEM 2 demonstration board can
be programmed with a PRO MATE II device program-
mer, PICSTART Plus development programmer, or
MPLAB ICD 2 with a Universal Programmer Adapter.
The MPLAB ICD 2 and MPLAB ICE in-circuit emulators
may also be used with the PICDEM 2 demonstration
board to test firmware. A prototype area extends the
circuitry for additional application components. Some
of the features include an RS-232 interface, a 2 x 16
LCD display, a piezo speaker, an on-board temperature
sensor, four LEDs and sample PIC18F452 and
PIC16F877 Flash microcontrollers.
25.15 PICDEM 1 PICmicro
Demonstration Board
The PICDEM 1 demonstration board demonstrates the
capabilities of the PIC16C5X (PIC16C54 to
PIC16C58A), PIC16C61, PIC16C62X, PIC16C71,
PIC16C8X, PIC17C42, PIC17C43 and PIC17C44. All
necessary hardware and software is included to run
basic demo programs. The sample microcontrollers
provided with the PICDEM 1 demonstration board can
be programmed with a PRO MATE II device program-
mer or a PICSTART Plus development programmer.
The PICDEM 1 demonstration board can be connected
to the MPLAB ICE in-circuit emulator for testing. A
prototype area extends the circuitry for additional appli-
cation components. Features include an RS-232
interface, a potentiometer for simulated analog input,
push button switches and eight LEDs.
25.18 PICDEM 3 PIC16C92X
Demonstration Board
The PICDEM 3 demonstration board supports the
PIC16C923 and PIC16C924 in the PLCC package. All
the necessary hardware and software is included to run
the demonstration programs.
25.19 PICDEM 4 8/14/18-Pin
Demonstration Board
The PICDEM 4 can be used to demonstrate the capa-
bilities of the 8, 14 and 18-pin PIC16XXXX and
PIC18XXXX MCUs, including the PIC16F818/819,
PIC16F87/88, PIC16F62XA and the PIC18F1320
family of microcontrollers. PICDEM 4 is intended to
showcase the many features of these low pin count
parts, including LIN and Motor Control using ECCP.
Special provisions are made for low-power operation
with the supercapacitor circuit and jumpers allow on-
board hardware to be disabled to eliminate current
draw in this mode. Included on the demo board are pro-
visions for Crystal, RC or Canned Oscillator modes, a
five volt regulator for use with a nine volt wall adapter
or battery, DB-9 RS-232 interface, ICD connector for
programming via ICSP and development with MPLAB
ICD 2, 2 x 16 liquid crystal display, PCB footprints for
H-Bridge motor driver, LIN transceiver and EEPROM.
Also included are: header for expansion, eight LEDs,
four potentiometers, three push buttons and a proto-
typing area. Included with the kit is a PIC16F627A and
a PIC18F1320. Tutorial firmware is included along
with the User’s Guide.
25.16 PICDEM.net Internet/Ethernet
Demonstration Board
The PICDEM.net demonstration board is an Internet/
Ethernet demonstration board using the PIC18F452
microcontroller and TCP/IP firmware. The board
supports any 40-pin DIP device that conforms to the
standard pinout used by the PIC16F877 or
PIC18C452. This kit features a user friendly TCP/IP
stack, web server with HTML, a 24L256 Serial
EEPROM for Xmodem download to web pages into
Serial EEPROM, ICSP/MPLAB ICD 2 interface con-
nector, an Ethernet interface, RS-232 interface and a
16 x 2 LCD display. Also included is the book and
CD-ROM “TCP/IP Lean, Web Servers for Embedded
Systems,” by Jeremy Bentham
DS39631A-page 320
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
25.20 PICDEM 17 Demonstration Board
25.24 PICDEM USB PIC16C7X5
Demonstration Board
The PICDEM 17 demonstration board is an evaluation
board that demonstrates the capabilities of several
Microchip microcontrollers, including PIC17C752,
PIC17C756A, PIC17C762 and PIC17C766. A pro-
grammed sample is included. The PRO MATE II device
programmer, or the PICSTART Plus development pro-
grammer, can be used to reprogram the device for user
tailored application development. The PICDEM 17
demonstration board supports program download and
execution from external on-board Flash memory. A
generous prototype area is available for user hardware
expansion.
The PICDEM USB Demonstration Board shows off the
capabilities of the PIC16C745 and PIC16C765 USB
microcontrollers. This board provides the basis for
future USB products.
25.25 Evaluation and
Programming Tools
In addition to the PICDEM series of circuits, Microchip
has a line of evaluation kits and demonstration software
for these products.
• KEELOQ evaluation and programming tools for
Microchip’s HCS Secure Data Products
25.21 PICDEM 18R PIC18C601/801
Demonstration Board
• CAN developers kit for automotive network
applications
The PICDEM 18R demonstration board serves to assist
development of the PIC18C601/801 family of Microchip
microcontrollers. It provides hardware implementation
of both 8-bit Multiplexed/Demultiplexed and 16-bit
Memory modes. The board includes 2 Mb external
Flash memory and 128 Kb SRAM memory, as well as
serial EEPROM, allowing access to the wide range of
memory types supported by the PIC18C601/801.
• Analog design boards and filter design software
• PowerSmart battery charging evaluation/
calibration kits
• IrDA® development kit
• microID development and rfLabTM development
software
• SEEVAL® designer kit for memory evaluation and
endurance calculations
25.22 PICDEM LIN PIC16C43X
Demonstration Board
• PICDEM MSC demo boards for Switching mode
power supply, high-power IR driver, delta sigma
ADC and flow rate sensor
The powerful LIN hardware and software kit includes a
series of boards and three PICmicro microcontrollers.
The small footprint PIC16C432 and PIC16C433 are
used as slaves in the LIN communication and feature
Check the Microchip web page and the latest Product
Selector Guide for the complete list of demonstration
and evaluation kits.
on-board LIN transceivers.
A PIC16F874 Flash
microcontroller serves as the master. All three micro-
controllers are programmed with firmware to provide
LIN bus communication.
25.23 PICkitTM 1 Flash Starter Kit
A complete “development system in a box”, the PICkit™
Flash Starter Kit includes a convenient multi-section
board for programming, evaluation and development of
8/14-pin Flash PIC® microcontrollers. Powered via USB,
the board operates under a simple Windows GUI. The
PICkit 1 Starter Kit includes the User’s Guide (on CD
ROM), PICkit 1 tutorial software and code for various
applications. Also included are MPLAB® IDE (Integrated
Development Environment) software, software and
hardware “Tips 'n Tricks for 8-pin Flash PIC®
Microcontrollers” Handbook and a USB interface cable.
Supports all current 8/14-pin Flash PIC microcontrollers,
as well as many future planned devices.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 321
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 322
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.0 ELECTRICAL CHARACTERISTICS
(†)
Absolute Maximum Ratings
Ambient temperature under bias.............................................................................................................-40°C to +125°C
Storage temperature .............................................................................................................................. -65°C to +150°C
Voltage on any pin with respect to VSS (except VDD, MCLR and RA4) .......................................... -0.3V to (VDD + 0.3V)
Voltage on VDD with respect to VSS ......................................................................................................... -0.3V to +7.5V
Voltage on MCLR with respect to VSS (Note 2) ......................................................................................... 0V to +13.25V
Total power dissipation (Note 1) ...............................................................................................................................1.0W
Maximum current out of VSS pin ...........................................................................................................................300 mA
Maximum current into VDD pin ..............................................................................................................................250 mA
Input clamp current, IIK (VI < 0 or VI > VDD)...................................................................................................................... 20 mA
Output clamp current, IOK (VO < 0 or VO > VDD) .............................................................................................................. 20 mA
Maximum output current sunk by any I/O pin..........................................................................................................25 mA
Maximum output current sourced by any I/O pin ....................................................................................................25 mA
Maximum current sunk by all ports .......................................................................................................................200 mA
Maximum current sourced by all ports ..................................................................................................................200 mA
Note 1: Power dissipation is calculated as follows:
Pdis = VDD x {IDD – ∑ IOH} + ∑ {(VDD – VOH) x IOH} + ∑(VOL x IOL)
2: Voltage spikes below VSS at the MCLR/VPP/RE3 pin, inducing currents greater than 80 mA, may cause
latch-up. Thus, a series resistor of 50-100Ω should be used when applying a “low” level to the MCLR/VPP/
RE3 pin, rather than pulling this pin directly to VSS.
† NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional operation of the device at those or any other conditions above those
indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for
extended periods may affect device reliability.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 323
PIC18F2420/2520/4420/4520
FIGURE 26-1:
PIC18F2420/2520/4420/4520 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL)
6.0V
5.5V
5.0V
4.5V
4.0V
PIC18FX42X/X52X
4.2V
3.5V
3.0V
2.5V
2.0V
40 MHz
Frequency
FIGURE 26-2:
PIC18LF2420/2520/4420/4520 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL)
6.0V
5.5V
5.0V
4.5V
4.0V
PIC18LFX42X/X52X
4.2V
3.5V
3.0V
2.5V
2.0V
40 MHz
4 MHz
Frequency
FMAX = (16.36 MHz/V) (VDDAPPMIN – 2.0V) + 4 MHz
Note: VDDAPPMIN is the minimum voltage of the PICmicro® device in the application.
DS39631A-page 324
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.1 DC Characteristics:Supply Voltage
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial)
PIC18LFX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18FX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
Param
Symbol
No.
Characteristic
Min
Typ
Max Units
Conditions
D001 VDD
D002 VDR
Supply Voltage
HS, XT, RC and LP Oscillator modes
2.0
1.5
—
—
5.5
—
V
V
RAM Data Retention
Voltage(1)
—
—
—
0.7
—
V
D003 VPOR
D004 SVDD
D005 VBOR
VDD Start Voltage
to ensure internal
Power-on Reset signal
See section on Power-on Reset for details
See section on Power-on Reset for details
0.05
V/ms
VDD Rise Rate
to ensure internal
Power-on Reset signal
Brown-out Reset Voltage
1.94
2.05
2.79
4.33
4.59
2.16
2.93
4.55
4.82
V
V
V
V
BORV1:BORV0 = 11
BORV1:BORV0 = 10
BORV1:BORV0 = 01
BORV1:BORV0 = 00
2.65
4.11
4.36
Legend: Shading of rows is to assist in readability of the table.
Note 1: This is the limit to which VDD can be lowered in Sleep mode, or during a device Reset, without losing RAM
data.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 325
PIC18F2420/2520/4420/4520
26.2 DC Characteristics: Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial)
PIC18LFX42X/X52X
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
(Industrial)
PIC18FX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
ParamNo.
Device
Power-down Current (IPD)
Typ
Max Units
Conditions
(1)
PIC18LFX42X/X52X 20
950
1.0
1.1
1.4
1.5
1.6
1.9
2.0
2.1
nA
µA
µA
µA
µA
µA
µA
µA
µA
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
VDD = 2.0V,
(Sleep mode)
0.02
0.6
PIC18LFX42X/X52X 0.03
VDD = 3.0V,
(Sleep mode)
0.03
0.8
All devices 0.04
0.04
VDD = 5.0V,
(Sleep mode)
1.7
Legend: Shading of rows is to assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured
with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that
add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin
loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have
an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be
estimated by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.
4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature
crystals are available at a much higher cost.
5: BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be
less than the sum of both specifications.
DS39631A-page 326
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.2 DC Characteristics: Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LFX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18FX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
Typ Max Units
-40°C ≤ TA ≤ +85°C for industrial
ParamNo.
Device
Supply Current (IDD)
Conditions
(2,3)
PIC18LFX42X/X52X 15
31.5
30
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
mA
mA
mA
mA
mA
mA
-40°C
15
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
15
28.5
63
PIC18LFX42X/X52X 40
FOSC = 31 kHz
(RC_RUN mode,
INTRC source)
35
60
30
57
All devices 105
168
160
152
630
600
570
1.3
1.2
1.1
2.3
2.2
2.1
90
80
PIC18LFX42X/X52X 0.32
0.33
0.33
PIC18LFX42X/X52X 0.6
FOSC = 1 MHz
(RC_RUN mode,
INTOSC source)
0.55
0.6
All devices 1.1
1.1
1.0
Legend: Shading of rows is to assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured
with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that
add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin
loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have
an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be
estimated by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.
4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature
crystals are available at a much higher cost.
5: BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be
less than the sum of both specifications.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 327
PIC18F2420/2520/4420/4520
26.2 DC Characteristics: Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LFX42X/X52X
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
(Industrial)
PIC18FX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
ParamNo.
Device
Supply Current (IDD)
Typ Max Units
Conditions
(2,3)
PIC18LFX42X/X52X 0.8
2.1
2.0
1.9
2.7
2.6
2.5
5.3
5.0
µA
µA
-40°C
0.8
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
0.8
µA
PIC18LFX42X/X52X 1.3
mA
mA
mA
mA
mA
FOSC = 4 MHz
(RC_RUN mode,
INTRC source)
1.3
1.3
All devices 2.5
2.5
2.5
4.8
6.5
mA
µA
µA
µA
µA
µA
µA
µA
µA
µA
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
PIC18LFX42X/X52X 2.9
3.1
6.2
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
3.6
5.9
PIC18LFX42X/X52X 4.5
10.1
9.6
FOSC = 31 kHz
(RC_IDLE mode,
INTRC source)
4.8
5.8
All devices 9.2
9.8
9.1
15.8
15
11.4
14.3
Legend: Shading of rows is to assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured
with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that
add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin
loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have
an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be
estimated by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.
4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature
crystals are available at a much higher cost.
5: BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be
less than the sum of both specifications.
DS39631A-page 328
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.2 DC Characteristics: Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LFX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18FX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
Typ Max Units
-40°C ≤ TA ≤ +85°C for industrial
ParamNo.
Device
Supply Current (IDD)
Conditions
(2,3)
PIC18LFX42X/X52X 165
315
300
285
470
450
430
840
800
760
525
500
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
-40°C
175
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
190
PIC18LFX42X/X52X 250
FOSC = 1 MHz
(RC_IDLE mode,
INTOSC source)
270
290
All devices 500
520
550
PIC18LFX42X/X52X 340
350
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
360
475
735
700
665
1.6
µA
µA
PIC18LFX42X/X52X 520
FOSC = 4 MHz
(RC_IDLE mode,
INTOSC source)
540
µA
580
µA
All devices 1.0
mA
mA
mA
1.1
1.1
1.5
1.4
Legend: Shading of rows is to assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured
with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that
add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin
loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have
an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be
estimated by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.
4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature
crystals are available at a much higher cost.
5: BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be
less than the sum of both specifications.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 329
PIC18F2420/2520/4420/4520
26.2 DC Characteristics: Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LFX42X/X52X
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
(Industrial)
PIC18FX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
ParamNo.
Device
Supply Current (IDD)
Typ Max Units
Conditions
(2,3)
PIC18LFX42X/X52X 250
420
400
380
740
700
670
1.6
1.5
1.4
1.6
1.5
1.4
2.6
2.5
2.4
4.7
4.5
4.3
26
µA
µA
-40°C
260
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
VDD = 4.2V
VDD = 5.0V
250
µA
PIC18LFX42X/X52X 550
µA
FOSC = 1 MHZ
(PRI_RUN,
EC oscillator)
480
µA
460
µA
All devices 1.2
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
1.1
1.0
PIC18LFX42X/X52X 0.72
0.74
0.74
PIC18LFX42X/X52X 1.3
FOSC = 4 MHz
(PRI_RUN,
EC oscillator)
1.3
1.3
All devices 2.7
2.6
2.5
All devices 15
16
25
FOSC = 40 MHZ
(PRI_RUN,
EC oscillator)
16
24
All devices 21
32
21
21
30
28
Legend: Shading of rows is to assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured
with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that
add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin
loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have
an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be
estimated by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.
4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature
crystals are available at a much higher cost.
5: BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be
less than the sum of both specifications.
DS39631A-page 330
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.2 DC Characteristics: Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LFX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18FX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
Typ Max Units
-40°C ≤ TA ≤ +85°C for industrial
ParamNo.
Device
Supply Current (IDD)
Conditions
(2,3)
All devices 7.5
16
15
14
21
20
19
35
34
33
46
45
43
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
-40°C
FOSC = 4 MHZ
(PRI_RUN HS+PLL)
7.4
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
VDD = 4.2V
VDD = 5.0V
VDD = 4.2V
VDD = 5.0V
7.3
All devices 10
FOSC = 4 MHZ
(PRI_RUN HS+PLL)
10
9.7
All devices 17
FOSC = 10 MHZ
(PRI_RUN HS+PLL)
17
17
All devices 23
FOSC = 10 MHZ
(PRI_RUN HS+PLL)
23
23
Legend: Shading of rows is to assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured
with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that
add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin
loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have
an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be
estimated by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.
4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature
crystals are available at a much higher cost.
5: BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be
less than the sum of both specifications.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 331
PIC18F2420/2520/4420/4520
26.2 DC Characteristics: Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LFX42X/X52X
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
(Industrial)
PIC18FX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
ParamNo.
Device
Supply Current (IDD)
Typ Max Units
Conditions
(2,3)
PIC18LFX42X/X52X 65
130
120
115
270
250
240
480
450
430
475
450
430
900
850
810
1.5
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
mA
mA
mA
mA
mA
mA
mA
mA
mA
-40°C
65
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
VDD = 4.2 V
VDD = 5.0V
70
PIC18LFX42X/X52X 120
FOSC = 1 MHz
(PRI_IDLE mode,
EC oscillator)
120
130
All devices 300
240
300
PIC18LFX42X/X52X 260
255
270
PIC18LFX42X/X52X 420
FOSC = 4 MHz
(PRI_IDLE mode,
EC oscillator)
430
450
All devices 0.9
0.9
1.4
0.9
1.3
All devices 6.0
9.5
6.2
9.0
FOSC = 40 MHz
(PRI_IDLE mode,
EC oscillator)
6.6
8.6
All devices 8.1
12.6
12.0
11.4
9.1
8.3
Legend: Shading of rows is to assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured
with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that
add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin
loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have
an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be
estimated by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.
4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature
crystals are available at a much higher cost.
5: BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be
less than the sum of both specifications.
DS39631A-page 332
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.2 DC Characteristics: Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LFX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18FX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
Typ Max Units
-40°C ≤ TA ≤ +85°C for industrial
ParamNo.
Device
Supply Current (IDD)
Conditions
(2,3)
PIC18LFX42X/X52X 14
31.5
30
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
-10°C
15
+25°C
+70°C
-10°C
+25°C
+70°C
-10°C
+25°C
+70°C
-10°C
+25°C
+70°C
-10°C
+25°C
+70°C
-10°C
+25°C
+70°C
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
16
29
(4)
PIC18LFX42X/X52X 40
74
FOSC = 32 kHz
35
70
(SEC_RUN mode,
Timer1 as clock)
31
67
All devices 99
126
120
114
7.4
7.0
6.7
10.5
10
81
75
PIC18LFX42X/X52X 2.5
3.7
4.5
(4)
PIC18LFX42X/X52X 5.0
FOSC = 32 kHz
5.4
(SEC_IDLE mode,
Timer1 as clock)
6.3
All devices 8.5
9.0
9.5
17
16
10.5
15
Legend: Shading of rows is to assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured
with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that
add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin
loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have
an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be
estimated by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.
4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature
crystals are available at a much higher cost.
5: BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be
less than the sum of both specifications.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 333
PIC18F2420/2520/4420/4520
26.2 DC Characteristics: Power-Down and Supply Current
PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
PIC18LFX42X/X52X
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
(Industrial)
PIC18FX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
Typ Max Units
Module Differential Currents (∆IWDT, ∆IBOR, ∆ILVD, ∆IOSCB, ∆IAD)
-40°C ≤ TA ≤ +85°C for industrial
ParamNo.
Device
Conditions
D022
(∆IWDT)
Watchdog Timer 1.3
7.6
8.0
µA
µA
µA
µA
µA
µA
µA
µA
µA
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
1.4
2.0
1.9
2.0
2.8
4.0
5.5
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
8.4
11.4
12.0
12.6
14.3
15.0
15.8
52
5.6
(5)
D022A
(∆IBOR)
Brown-out Reset
35
40
µA -40°C to +85°C
µA -40°C to +85°C
VDD = 3.0V
VDD = 5.0V
63
Sleep mode,
BOREN1:BOREN0 = 10
40
63
47
µA -40°C to +85°C
µA -40°C to +85°C
VDD = 5.0V
VDD = 2.0V
D022B
(∆ILVD)
High/Low-Voltage 22
(5)
Detect
25
58
69
µA -40°C to +85°C
µA -40°C to +85°C
VDD = 3.0V
VDD = 5.0V
29
D025
(∆IOSCB)
Timer1 Oscillator 0.01
4.8
5.0
5.3
7.6
8.0
8.4
9.5
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
-10°C
+25°C
+70°C
-10°C
+25°C
+70°C
-10°C
+25°C
+70°C
(4)
0.01
0.01
0.01
0.01
0.01
0.01
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
32 kHz on Timer1
(4)
32 kHz on Timer1
(4)
0.01 10.0
0.01 10.5
32 kHz on Timer1
D026
(∆IAD)
A/D Converter 1.0
2.0
2.0
2.0
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
1.0
1.0
A/D on, not converting
Legend: Shading of rows is to assist in readability of the table.
Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured
with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that
add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.).
2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin
loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have
an impact on the current consumption.
The test conditions for all IDD measurements in active operation mode are:
OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;
MCLR = VDD; WDT enabled/disabled as specified.
3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be
estimated by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.
4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature
crystals are available at a much higher cost.
5: BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be
less than the sum of both specifications.
DS39631A-page 334
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.3 DC Characteristics: PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial)
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
DC CHARACTERISTICS
Param
Symbol
No.
Characteristic
Min
Max
Units
Conditions
VIL
Input Low Voltage
I/O ports:
with TTL buffer
D030
D030A
D031
VSS
—
0.15 VDD
0.8
V
V
VDD < 4.5V
4.5V ≤ VDD ≤ 5.5V
with Schmitt Trigger buffer
RC3 and RC4
VSS
VSS
0.2 VDD
0.3 VDD
V
V
D032
D033
MCLR
VSS
VSS
0.2 VDD
0.3 VDD
V
V
OSC1
HS, HSPLL modes
D033A
D033B
D034
OSC1
OSC1
T13CKI
VSS
VSS
VSS
0.2 VDD
0.3 VDD
0.3 VDD
V
V
V
RC, EC modes(1)
XT, LP modes
VIH
Input High Voltage
I/O ports:
D040
D040A
D041
with TTL buffer
0.25 VDD + 0.8V
2.0
VDD
VDD
V
V
VDD < 4.5V
4.5V ≤ VDD ≤ 5.5V
with Schmitt Trigger buffer
RC3 and RC4
0.8 VDD
0.7 VDD
VDD
VDD
V
V
D042
D043
MCLR
OSC1
0.8 VDD
0.7 VDD
VDD
VDD
V
V
HS, HSPLL modes
D043A
D043B
D043C
D044
OSC1
OSC1
OSC1
T13CKI
0.8 VDD
0.9 VDD
1.6
VDD
VDD
VDD
VDD
V
V
V
V
EC mode
RC mode(1)
XT, LP modes
1.6
IIL
Input Leakage Current(2,3)
D060
I/O ports
—
1
µA VSS ≤ VPIN ≤ VDD,
Pin at high-impedance
D061
D063
MCLR
—
—
5
5
µA Vss ≤ VPIN ≤ VDD
µA Vss ≤ VPIN ≤ VDD
OSC1
IPU
Weak Pull-up Current
PORTB weak pull-up current
D070
IPURB
50
400
µA VDD = 5V, VPIN = VSS
Note 1: In RC oscillator configuration, the OSC1/CLKI pin is a Schmitt Trigger input. It is not recommended that the
PICmicro® device be driven with an external clock while in RC mode.
2: The leakage current on the MCLR pin is strongly dependent on the applied voltage level. The specified
levels represent normal operating conditions. Higher leakage current may be measured at different input
voltages.
3: Negative current is defined as current sourced by the pin.
4: Parameter is characterized but not tested.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 335
PIC18F2420/2520/4420/4520
26.3 DC Characteristics: PIC18F2420/2520/4420/4520 (Industrial)
PIC18LF2420/2520/4420/4520 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
DC CHARACTERISTICS
Param
Symbol
No.
Characteristic
Min
Max
Units
Conditions
VOL
VOH
Output Low Voltage
I/O ports
D080
D083
—
—
0.6
0.6
V
V
IOL = 8.5 mA, VDD = 4.5V,
-40°C to +85°C
OSC2/CLKO
(RC, RCIO, EC, ECIO modes)
Output High Voltage(3)
IOL = 1.6 mA, VDD = 4.5V,
-40°C to +85°C
D090
D092
I/O ports
VDD – 0.7
VDD – 0.7
—
—
V
V
IOH = -3.0 mA, VDD = 4.5V,
-40°C to +85°C
OSC2/CLKO
IOH = -1.3 mA, VDD = 4.5V,
(RC, RCIO, EC, ECIO modes)
-40°C to +85°C
Capacitive Loading Specs
on Output Pins
D100(4)
—
COSC2 OSC2 pin
15
pF In XT, HS and LP modes
when external clock is
used to drive OSC1
D101
D102
CIO
CB
All I/O pins and OSC2
(in RC mode)
—
—
50
pF To meet the AC Timing
Specifications
pF I2C™ Specification
SCL, SDA
400
Note 1: In RC oscillator configuration, the OSC1/CLKI pin is a Schmitt Trigger input. It is not recommended that the
PICmicro® device be driven with an external clock while in RC mode.
2: The leakage current on the MCLR pin is strongly dependent on the applied voltage level. The specified
levels represent normal operating conditions. Higher leakage current may be measured at different input
voltages.
3: Negative current is defined as current sourced by the pin.
4: Parameter is characterized but not tested.
DS39631A-page 336
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 26-1: MEMORY PROGRAMMING REQUIREMENTS
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
DC CHARACTERISTICS
Param
Sym
No.
Characteristic
Min
Typ†
Max
Units
Conditions
Internal Program Memory
Programming Specifications(1)
D110
D113
VPP
Voltage on MCLR/VPP/RE3 pin
9.00
—
—
—
13.25
10
V
(Note 3)
IDDP
Supply Current during
Programming
mA
Data EEPROM Memory
D120
ED
Byte Endurance
100K
VMIN
1M
—
—
E/W -40°C to +85°C
D121 VDRW VDD for Read/Write
5.5
V
Using EECON to read/write
VMIN = Minimum operating
voltage
D122 TDEW Erase/Write Cycle Time
D123 TRETD Characteristic Retention
—
4
—
—
ms
40
—
Year Provided no other
specifications are violated
D124
TREF
Number of Total Erase/Write
Cycles before Refresh(2)
1M
10M
—
E/W -40°C to +85°C
Program Flash Memory
Cell Endurance
—
D130
D131
EP
10K
100K
—
E/W -40°C to +85°C
VPR
VDD for Read
VMIN
5.5
V
VMIN = Minimum operating
voltage
—
—
D132
VIE
VDD for Block Erase
4.5
4.5
5.5
5.5
V
V
Using ICSP port
Using ICSP port
D132A VIW
VDD for Externally Timed Erase
or Write
—
D132B VPEW VDD for Self-timed Write
VMIN
5.5
V
VMIN = Minimum operating
voltage
D133
TIE
ICSP Block Erase Cycle Time
—
1
4
—
—
ms VDD > 4.5V
ms VDD > 4.5V
D133A TIW
ICSP Erase or Write Cycle Time
(externally timed)
—
D133A TIW
Self-timed Write Cycle Time
—
2
—
—
ms
D134 TRETD Characteristic Retention
40
100
Year Provided no other
specifications are violated
†
Data in “Typ” column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance
only and are not tested.
Note 1: These specifications are for programming the on-chip program memory through the use of table write
instructions.
2: Refer to Section 7.8 “Using the Data EEPROM” for a more detailed discussion on data EEPROM
endurance.
3: Required only if single-supply programming is disabled.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 337
PIC18F2420/2520/4420/4520
TABLE 26-2: COMPARATOR SPECIFICATIONS
Operating Conditions: 3.0V < VDD < 5.5V, -40°C < TA < +85°C (unless otherwise stated).
Param
No.
Sym
Characteristics
Input Offset Voltage
Min
Typ
Max
Units
Comments
D300
VIOFF
—
0
±5.0
—
±10
VDD – 1.5
—
mV
V
D301
D302
300
VICM
Input Common Mode Voltage*
Common Mode Rejection Ratio*
Response Time(1)*
CMRR
TRESP
55
—
—
—
dB
ns
ns
150
150
400
PIC18FXXXX
300A
600
PIC18LFXXXX,
VDD = 2.0V
301
TMC2OV Comparator Mode Change to
Output Valid*
—
—
10
µs
*
These parameters are characterized but not tested.
Note 1: Response time measured with one comparator input at (VDD – 1.5)/2, while the other input transitions
from VSS to VDD.
TABLE 26-3: VOLTAGE REFERENCE SPECIFICATIONS
Operating Conditions: 3.0V < VDD < 5.5V, -40°C < TA < +85°C (unless otherwise stated).
Param
No.
Sym
Characteristics
Resolution
Min
Typ
Max
Units
Comments
D310
VRES
VDD/24
—
—
—
2k
—
VDD/32
1/2
LSb
D311
D312
310
VRAA
VRUR
TSET
Absolute Accuracy
Unit Resistor Value (R)*
Settling Time(1)*
LSb Low Range (CVRR = 1)
—
—
Ω
—
10
µs
*
These parameters are characterized but not tested.
Note 1: Settling time measured while CVRR = 1and CVR3:CVR0 transitions from ‘0000’ to ‘1111’.
DS39631A-page 338
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-3:
HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS
VDD
(HLVDIF can be
cleared in software)
VLVD
(HLVDIF set by hardware)
HLVDIF
TABLE 26-4: HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
Param
No.
Symbol
Characteristic
Min
Typ† Max
Units
Conditions
D420
HLVD Voltage on VDD LVV = 0000 2.12
2.17
2.23
2.36
2.44
2.60
2.79
2.89
3.12
3.39
3.55
3.71
3.90
4.11
4.33
4.59
2.22
2.28
2.42
2.49
2.66
2.85
2.95
3.19
3.47
3.63
3.80
3.99
4.20
4.43
4.69
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
Transition High-to-Low
LVV = 0001 2.18
LVV = 0010 2.31
LVV = 0011 2.38
LVV = 0100 2.54
LVV = 0101 2.72
LVV = 0110 2.82
LVV = 0111 3.05
LVV = 1000 3.31
LVV = 1001 3.46
LVV = 1010 3.63
LVV = 1011 3.81
LVV = 1100 4.01
LVV = 1101 4.23
LVV = 1110 4.48
†
Production tested at TAMB = 25°C. Specifications over temperature limits ensured by characterization.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 339
PIC18F2420/2520/4420/4520
26.4 AC (Timing) Characteristics
26.4.1
TIMING PARAMETER SYMBOLOGY
The timing parameter symbols have been created
using one of the following formats:
1. TppS2ppS
2. TppS
T
3. TCC:ST
4. Ts
(I2C specifications only)
(I2C specifications only)
F
Frequency
T
Time
Lowercase letters (pp) and their meanings:
pp
cc
ck
cs
di
CCP1
CLKO
CS
osc
rd
OSC1
RD
rw
sc
ss
t0
RD or WR
SCK
SDI
do
dt
SDO
SS
Data in
I/O port
MCLR
T0CKI
T13CKI
WR
io
t1
mc
wr
Uppercase letters and their meanings:
S
F
Fall
P
R
V
Z
Period
H
High
Rise
I
L
Invalid (High-impedance)
Low
Valid
High-impedance
I2C only
AA
output access
Bus free
High
Low
High
Low
BUF
TCC:ST (I2C specifications only)
CC
HD
Hold
SU
Setup
ST
DAT
STA
DATA input hold
Start condition
STO
Stop condition
DS39631A-page 340
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
26.4.2
TIMING CONDITIONS
Note:
Because of space limitations, the generic
terms “PIC18FXXXX” and “PIC18LFXXXX”
are used throughout this section to refer to
the PIC18F2420/2520/4420/4520 and
PIC18LF2420/2520/4420/4520 families of
devices specifically and only those devices.
The temperature and voltages specified in Table 26-5
apply to all timing specifications unless otherwise
noted. Figure 26-4 specifies the load conditions for the
timing specifications.
TABLE 26-5: TEMPERATURE AND VOLTAGE SPECIFICATIONS – AC
Standard Operating Conditions (unless otherwise stated)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
AC CHARACTERISTICS
Operating voltage VDD range as described in DC spec Section 26.1 and
Section 26.3.
LF parts operate for industrial temperatures only.
FIGURE 26-4:
LOAD CONDITIONS FOR DEVICE TIMING SPECIFICATIONS
Load Condition 1 Load Condition 2
VDD/2
CL
RL
Pin
VSS
CL
Pin
RL = 464Ω
CL = 50 pF for all pins except OSC2/CLKO
and including D and E outputs as ports
VSS
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 341
PIC18F2420/2520/4420/4520
26.4.3
TIMING DIAGRAMS AND SPECIFICATIONS
FIGURE 26-5:
EXTERNAL CLOCK TIMING (ALL MODES EXCEPT PLL)
Q4
Q1
1
Q2
Q3
Q4
Q1
OSC1
CLKO
3
4
3
4
2
TABLE 26-6: EXTERNAL CLOCK TIMING REQUIREMENTS
Param.
Symbol
Characteristic
Min
Max
Units
Conditions
No.
1A
FOSC
External CLKI Frequency(1)
Oscillator Frequency(1)
DC
DC
0.1
4
40
4
MHz EC, ECIO Oscillator mode
MHz RC Oscillator mode
MHz XT Oscillator mode
MHz HS Oscillator mode
MHz HS + PLL Oscillator mode
kHz LP Oscillator mode
4
25
4
10
5
33
1
TOSC
External CLKI Period(1)
Oscillator Period(1)
25
250
250
—
ns
ns
ns
EC, ECIO Oscillator mode
RC Oscillator mode
—
10,000
XT Oscillator mode
40
100
250
250
ns
ns
HS Oscillator mode
HS + PLL Oscillator mode
30
100
30
2.5
10
—
—
—
µs
ns
ns
µs
ns
ns
ns
ns
LP Oscillator mode
TCY = 4/FOSC
2
3
TCY
Instruction Cycle Time(1)
TOSL,
TOSH
External Clock in (OSC1)
High or Low Time
—
XT Oscillator mode
LP Oscillator mode
HS Oscillator mode
XT Oscillator mode
LP Oscillator mode
HS Oscillator mode
—
—
4
TOSR,
TOSF
External Clock in (OSC1)
Rise or Fall Time
20
50
7.5
—
—
Note 1: Instruction cycle period (TCY) equals four times the input oscillator time base period for all configurations
except PLL. All specified values are based on characterization data for that particular oscillator type under
standard operating conditions with the device executing code. Exceeding these specified limits may result
in an unstable oscillator operation and/or higher than expected current consumption. All devices are tested
to operate at “min.” values with an external clock applied to the OSC1/CLKI pin. When an external clock
input is used, the “max.” cycle time limit is “DC” (no clock) for all devices.
DS39631A-page 342
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
TABLE 26-7: PLL CLOCK TIMING SPECIFICATIONS (VDD = 4.2V TO 5.5V)
Param
No.
Sym
Characteristic
Min
Typ†
Max
Units Conditions
F10
F11
F12
F13
FOSC Oscillator Frequency Range
4
—
—
—
—
10
40
2
MHz HS mode only
FSYS On-Chip VCO System Frequency
16
—
-2
MHz HS mode only
trc
PLL Start-up Time (Lock Time)
ms
%
∆CLK CLKO Stability (Jitter)
+2
†
Data in “Typ” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance
only and are not tested.
TABLE 26-8: AC CHARACTERISTICS: INTERNAL RC ACCURACY
PIC18F2420/2520/4420/4520 (INDUSTRIAL)
PIC18LF2420/2520/4420/4520 (INDUSTRIAL)
PIC18LFX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18FX42X/X52X
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
Param
No.
Device
Min
Typ
Max
Units
Conditions
INTOSC Accuracy @ Freq = 8 MHz, 4 MHz, 2 MHz, 1 MHz, 500 kHz, 250 kHz, 125 kHz(1)
PIC18LFX42X/X52X
PIC18FX42X/X52X
-2
-5
+/-1
—
2
5
%
%
%
%
%
%
+25°C
VDD = 2.7-3.3V
VDD = 2.7-3.3V
VDD = 2.7-3.3V
VDD = 4.5-5.5V
VDD = 4.5-5.5V
VDD = 4.5-5.5V
-10°C to +85°C
-40°C to +85°C
+25°C
-10
-2
+/-1
+/-1
—
10
2
-5
5
-10°C to +85°C
-40°C to +85°C
-10
+/-1
10
INTRC Accuracy @ Freq = 31 kHz(2)
PIC18LFX42X/X52X 26.562
PIC18FX42X/X52X 26.562
—
—
35.938 kHz
35.938 kHz
-40°C to +85°C
-40°C to +85°C
VDD = 2.7-3.3V
VDD = 4.5-5.5V
Legend: Shading of rows is to assist in readability of the table.
Note 1: Frequency calibrated at 25°C. OSCTUNE register can be used to compensate for temperature drift.
2: INTRC frequency after calibration.
3: Change of INTRC frequency as VDD changes.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 343
PIC18F2420/2520/4420/4520
FIGURE 26-6:
CLKO AND I/O TIMING
Q1
Q2
Q3
Q4
OSC1
11
10
CLKO
13
14
12
19
18
16
I/O pin
(Input)
15
17
I/O pin
(Output)
New Value
Old Value
20, 21
Note:
Refer to Figure 26-4 for load conditions.
TABLE 26-9: CLKO AND I/O TIMING REQUIREMENTS
Param
Symbol
Characteristic
Min
Typ
Max
Units Conditions
No.
10
TosH2ckL OSC1 ↑ to CLKO ↓
TosH2ckH OSC1 ↑ to CLKO ↑
—
—
—
—
—
75
75
35
35
—
—
—
50
—
—
200
200
100
100
ns
ns
ns
ns
(Note 1)
(Note 1)
(Note 1)
(Note 1)
(Note 1)
(Note 1)
(Note 1)
11
12
13
14
15
16
17
18
18A
TckR
TckF
CLKO Rise Time
CLKO Fall Time
TckL2ioV CLKO ↓ to Port Out Valid
TioV2ckH Port In Valid before CLKO ↑
TckH2ioI Port In Hold after CLKO ↑
TosH2ioV OSC1 ↑ (Q1 cycle) to Port Out Valid
0.5 TCY + 20 ns
0.25 TCY + 25
—
—
ns
ns
ns
ns
0
—
150
—
TosH2ioI OSC1 ↑ (Q2 cycle) to
Port Input Invalid
PIC18FXXXX
100
200
PIC18LFXXXX
—
ns VDD = 2.0V
(I/O in hold time)
19
TioV2osH Port Input Valid to OSC1 ↑ (I/O in setup time)
0
—
—
10
—
10
—
—
—
—
25
60
25
60
—
—
ns
20
TioR
Port Output Rise Time
Port Output Fall Time
INT pin High or Low Time
PIC18FXXXX
PIC18LFXXXX
PIC18FXXXX
PIC18LFXXXX
ns
20A
21
—
ns VDD = 2.0V
TioF
—
ns
21A
22†
23†
24†
—
ns VDD = 2.0V
TINP
TCY
TCY
20
ns
ns
ns
TRBP
TRCP
RB7:RB4 Change INT High or Low Time
RC7:RC4 Change INT High or Low Time
†
These parameters are asynchronous events not related to any internal clock edges.
Note 1: Measurements are taken in RC mode, where CLKO output is 4 x TOSC.
DS39631A-page 344
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-7:
RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND
POWER-UP TIMER TIMING
VDD
MCLR
30
Internal
POR
33
PWRT
Time-out
32
OSC
Time-out
Internal
Reset
Watchdog
Timer
Reset
31
34
34
I/O pins
Note:
Refer to Figure 26-4 for load conditions.
FIGURE 26-8:
BROWN-OUT RESET TIMING
BVDD
VDD
35
VBGAP = 1.2V
VIRVST
Enable Internal
Reference Voltage
Internal Reference
Voltage Stable
36
TABLE 26-10: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER
AND BROWN-OUT RESET REQUIREMENTS
Param.
No.
Symbol
Characteristic
Min
Typ
Max
Units
Conditions
30
TmcL
TWDT
MCLR Pulse Width (low)
2
—
—
µs
ms
31
Watchdog Timer Time-out Period
(no postscaler)
—
4.00
TBD
32
33
34
TOST
Oscillation Start-up Timer Period
1024 TOSC
—
65.5
2
1024 TOSC
TBD
—
ms
µs
TOSC = OSC1 period
TPWRT Power-up Timer Period
—
—
TIOZ
I/O High-Impedance from MCLR
Low or Watchdog Timer Reset
—
35
36
TBOR
Brown-out Reset Pulse Width
200
—
—
—
µs VDD ≤ BVDD (see D005)
µs
TIVRST Time for Internal Reference
Voltage to become Stable
20
50
37
38
39
TLVD
TCSD
High/Low-Voltage Detect Pulse Width
CPU Start-up Time
200
5
—
—
1
—
10
—
µs
µs
ms
VDD ≤ VLVD
TIOBST Time for INTOSC to Stabilize
—
Legend: TBD = To Be Determined
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 345
PIC18F2420/2520/4420/4520
FIGURE 26-9:
TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
T0CKI
41
40
42
T1OSO/T13CKI
46
45
47
48
TMR0 or
TMR1
Note:
Refer to Figure 26-4 for load conditions.
TABLE 26-11: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS
Param
Symbol
Characteristic
Min
Max Units Conditions
No.
40
Tt0H
T0CKI High Pulse Width
No prescaler
With prescaler
No prescaler
With prescaler
No prescaler
With prescaler
0.5 TCY + 20
10
—
—
—
—
—
—
ns
ns
ns
ns
ns
41
42
Tt0L
Tt0P
T0CKI Low Pulse Width
T0CKI Period
0.5 TCY + 20
10
TCY + 10
Greater of:
20 ns or
ns N = prescale
value
(TCY + 40)/N
(1, 2, 4,..., 256)
45
46
Tt1H
Tt1L
T13CKI
High Time
Synchronous, no prescaler
0.5 TCY + 20
—
—
—
—
—
—
—
—
—
—
—
ns
Synchronous, PIC18FXXXX
10
ns
with prescaler
PIC18LFXXXX
25
ns VDD = 2.0V
Asynchronous PIC18FXXXX
PIC18LFXXXX
30
ns
50
ns VDD = 2.0V
T13CKI Low Synchronous, no prescaler
Time
0.5 TCY + 5
ns
Synchronous, PIC18FXXXX
10
25
30
50
ns
with prescaler
PIC18LFXXXX
ns VDD = 2.0V
ns
Asynchronous PIC18FXXXX
PIC18LFXXXX
ns VDD = 2.0V
47
48
Tt1P
Ft1
T13CKI
Input Period
Synchronous
Greater of:
20 ns or
(TCY + 40)/N
ns N = prescale
value (1, 2, 4, 8)
Asynchronous
60
DC
—
50
ns
kHz
—
T13CKI Oscillator Input Frequency Range
Tcke2tmrI Delay from External T13CKI Clock Edge to
Timer Increment
2 TOSC
7 TOSC
DS39631A-page 346
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-10:
CAPTURE/COMPARE/PWM TIMINGS (ALL CCP MODULES)
CCPx
(Capture Mode)
50
51
52
54
CCPx
(Compare or PWM Mode)
53
Refer to Figure 26-4 for load conditions.
Note:
TABLE 26-12: CAPTURE/COMPARE/PWM REQUIREMENTS (ALL CCP MODULES)
Param
Symbol
Characteristic
Min
Max
Units
Conditions
No.
50
TccL
CCPx Input Low No prescaler
0.5 TCY + 20
—
—
—
—
—
—
—
ns
ns
ns
ns
ns
ns
ns
Time
With
PIC18FXXXX
10
prescaler
PIC18LFXXXX
20
VDD = 2.0V
VDD = 2.0V
51
TccH
CCPx Input
High Time
No prescaler
0.5 TCY + 20
With
PIC18FXXXX
10
20
prescaler
PIC18LFXXXX
52
53
TccP
TccR
CCPx Input Period
3 TCY + 40
N
N = prescale
value (1, 4 or 16)
CCPx Output Fall Time
PIC18FXXXX
PIC18LFXXXX
PIC18FXXXX
PIC18LFXXXX
—
—
—
—
25
45
25
45
ns
ns
ns
ns
VDD = 2.0V
VDD = 2.0V
54
TccF
CCPx Output Fall Time
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 347
PIC18F2420/2520/4420/4520
FIGURE 26-11:
PARALLEL SLAVE PORT TIMING (PIC18F4420/4520)
RE2/CS
RE0/RD
RE1/WR
65
RD7:RD0
62
64
63
Note:
Refer to Figure 26-4 for load conditions.
TABLE 26-13: PARALLEL SLAVE PORT REQUIREMENTS (PIC18F4420/4520)
Param.
Symbol
Characteristic
Min
Max Units
Conditions
No.
62
TdtV2wrH
Data In Valid before WR ↑ or CS ↑
(setup time)
20
—
ns
63
TwrH2dtI
WR ↑ or CS ↑ to Data–In
Invalid (hold time)
PIC18FXXXX
20
—
—
ns
PIC18LFXXXX 35
ns VDD = 2.0V
64
65
66
TrdL2dtV
TrdH2dtI
TibfINH
RD ↓ and CS ↓ to Data–Out Valid
RD ↑ or CS ↓ to Data–Out Invalid
—
10
—
80
ns
ns
30
Inhibit of the IBF Flag bit being Cleared from
3 TCY
WR ↑ or CS ↑
DS39631A-page 348
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-12:
EXAMPLE SPI MASTER MODE TIMING (CKE = 0)
SS
70
SCK
(CKP = 0)
71
72
78
79
79
SCK
(CKP = 1)
78
80
bit 6 - - - - - -1
MSb
LSb
SDO
SDI
75, 76
MSb In
74
bit 6 - - - -1
LSb In
73
Note: Refer to Figure 26-4 for load conditions.
TABLE 26-14: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 0)
Param
No.
Symbol
Characteristic
Min
Max Units Conditions
70
TssL2scH, SS ↓ to SCK ↓ or SCK ↑ Input
TssL2scL
TCY
—
ns
71
TscH
SCK Input High Time
(Slave mode)
Continuous
Single Byte
Continuous
Single Byte
1.25 TCY + 30
—
—
—
—
—
ns
71A
72
40
1.25 TCY + 30
40
ns (Note 1)
TscL
SCK Input Low Time
(Slave mode)
ns
72A
73
ns (Note 1)
TdiV2scH, Setup Time of SDI Data Input to SCK Edge
TdiV2scL
100
ns
73A
74
Tb2b
Last Clock Edge of Byte 1 to the 1st Clock Edge 1.5 TCY + 40
of Byte 2
—
—
ns (Note 2)
TscH2diL, Hold Time of SDI Data Input to SCK Edge
TscL2diL
100
ns
75
TdoR
SDO Data Output Rise Time PIC18FXXXX
PIC18LFXXXX
—
—
—
—
—
—
—
—
25
45
25
25
45
25
50
100
ns
ns VDD = 2.0V
76
78
TdoF
TscR
SDO Data Output Fall Time
ns
SCK Output Rise Time
(Master mode)
PIC18FXXXX
PIC18LFXXXX
ns
ns VDD = 2.0V
79
80
TscF
SCK Output Fall Time (Master mode)
ns
TscH2doV, SDO Data Output Valid after PIC18FXXXX
TscL2doV SCK Edge
ns
PIC18LFXXXX
ns VDD = 2.0V
Note 1: Requires the use of Parameter #73A.
2: Only if Parameter #71A and #72A are used.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 349
PIC18F2420/2520/4420/4520
FIGURE 26-13:
EXAMPLE SPI MASTER MODE TIMING (CKE = 1)
SS
81
SCK
(CKP = 0)
71
72
79
78
73
SCK
(CKP = 1)
80
LSb
MSb
bit 6 - - - - - -1
SDO
SDI
75, 76
MSb In
74
bit 6 - - - -1
LSb In
Note: Refer to Figure 26-4 for load conditions.
TABLE 26-15: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 1)
Param.
No.
Symbol
TscH
TscL
Characteristic
Min
Max Units Conditions
71
SCK Input High Time
Continuous
Single Byte
Continuous
Single Byte
1.25 TCY + 30
—
—
—
—
—
ns
(Slave mode)
71A
72
40
1.25 TCY + 30
40
ns (Note 1)
SCK Input Low Time
(Slave mode)
ns
72A
73
ns (Note 1)
TdiV2scH, Setup Time of SDI Data Input to SCK Edge
TdiV2scL
100
ns
73A
74
Tb2b
Last Clock Edge of Byte 1 to the 1st Clock Edge
of Byte 2
1.5 TCY + 40
—
—
ns (Note 2)
TscH2diL,
TscL2diL
Hold Time of SDI Data Input to SCK Edge
100
—
ns
75
TdoR
SDO Data Output Rise Time PIC18FXXXX
PIC18LFXXXX
25
45
25
25
45
25
50
100
—
ns
ns VDD = 2.0V
76
78
TdoF
TscR
SDO Data Output Fall Time
—
—
ns
SCK Output Rise Time
(Master mode)
PIC18FXXXX
ns
PIC18LFXXXX
ns VDD = 2.0V
79
80
TscF
SCK Output Fall Time (Master mode)
—
—
ns
TscH2doV, SDO Data Output Valid after PIC18FXXXX
TscL2doV SCK Edge
ns
PIC18LFXXXX
ns VDD = 2.0V
ns
81
TdoV2scH, SDO Data Output Setup to SCK Edge
TdoV2scL
TCY
Note 1: Requires the use of Parameter #73A.
2: Only if Parameter #71A and #72A are used.
DS39631A-page 350
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-14:
EXAMPLE SPI SLAVE MODE TIMING (CKE = 0)
SS
70
SCK
(CKP = 0)
83
71
72
78
79
79
78
SCK
(CKP = 1)
80
MSb
LSb
SDO
SDI
bit 6 - - - - - -1
77
75, 76
MSb In
74
bit 6 - - - -1
LSb In
73
Note:
Refer to Figure 26-4 for load conditions.
TABLE 26-16: EXAMPLE SPI MODE REQUIREMENTS (SLAVE MODE TIMING, CKE = 0)
Param
No.
Symbol
Characteristic
Min
Max Units Conditions
70
TssL2scH, SS ↓ to SCK ↓ or SCK ↑ Input
TssL2scL
TCY
—
ns
71
TscH
SCK Input High Time
(Slave mode)
Continuous
Single Byte
Continuous
Single Byte
1.25 TCY + 30
—
—
—
—
—
ns
71A
72
40
1.25 TCY + 30
40
ns (Note 1)
TscL
SCK Input Low Time
(Slave mode)
ns
72A
73
ns (Note 1)
TdiV2scH, Setup Time of SDI Data Input to SCK Edge
TdiV2scL
100
ns
73A
74
Tb2b
Last Clock Edge of Byte 1 to the First Clock Edge of Byte 2 1.5 TCY + 40
—
—
ns (Note 2)
TscH2diL, Hold Time of SDI Data Input to SCK Edge
TscL2diL
100
ns
75
TdoR
SDO Data Output Rise Time
PIC18FXXXX
—
25
45
25
50
25
45
25
50
100
—
ns
PIC18LFXXXX
ns VDD = 2.0V
76
77
78
TdoF
SDO Data Output Fall Time
—
10
—
ns
TssH2doZ SS↑ to SDO Output High-Impedance
TscR
ns
SCK Output Rise Time (Master mode) PIC18FXXXX
PIC18LFXXXX
ns
ns VDD = 2.0V
79
80
TscF
SCK Output Fall Time (Master mode)
—
—
ns
TscH2doV, SDO Data Output Valid after SCK Edge PIC18FXXXX
TscL2doV
ns
PIC18LFXXXX
ns VDD = 2.0V
ns
83
TscH2ssH, SS ↑ after SCK edge
TscL2ssH
1.5 TCY + 40
Note 1: Requires the use of Parameter #73A.
2: Only if Parameter #71A and #72A are used.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 351
PIC18F2420/2520/4420/4520
FIGURE 26-15:
EXAMPLE SPI SLAVE MODE TIMING (CKE = 1)
82
SS
70
SCK
83
(CKP = 0)
71
72
SCK
(CKP = 1)
80
MSb
bit 6 - - - - - -1
LSb
SDO
SDI
75, 76
77
MSb In
74
bit 6 - - - -1
LSb In
Note: Refer to Figure 26-4 for load conditions.
TABLE 26-17: EXAMPLE SPI SLAVE MODE REQUIREMENTS (CKE = 1)
Param
No.
Symbol
Characteristic
Min
Max Units Conditions
70
TssL2scH, SS ↓ to SCK ↓ or SCK ↑ Input
TssL2scL
TCY
—
ns
71
TscH
TscL
Tb2b
SCK Input High Time
(Slave mode)
Continuous
Single Byte
Continuous
Single Byte
1.25 TCY + 30
—
—
—
—
—
—
ns
71A
72
40
1.25 TCY + 30
40
ns (Note 1)
ns
SCK Input Low Time
(Slave mode)
72A
73A
74
ns (Note 1)
ns (Note 2)
ns
Last Clock Edge of Byte 1 to the First Clock Edge of Byte 2 1.5 TCY + 40
TscH2diL, Hold Time of SDI Data Input to SCK Edge
TscL2diL
100
75
TdoR
SDO Data Output Rise Time
PIC18FXXXX
—
25
45
25
50
25
45
25
50
100
50
100
—
ns
PIC18LFXXXX
ns VDD = 2.0V
76
77
78
TdoF
SDO Data Output Fall Time
—
ns
TssH2doZ SS↑ to SDO Output High-Impedance
TscR
10
ns
SCK Output Rise Time
(Master mode)
PIC18FXXXX
—
ns
PIC18LFXXXX
—
ns VDD = 2.0V
79
80
TscF
SCK Output Fall Time (Master mode)
—
ns
TscH2doV, SDO Data Output Valid after SCK PIC18FXXXX
TscL2doV Edge
—
ns
PIC18LFXXXX
—
ns VDD = 2.0V
82
83
TssL2doV SDO Data Output Valid after SS ↓ PIC18FXXXX
—
—
ns
Edge
PIC18LFXXXX
ns VDD = 2.0V
ns
TscH2ssH, SS ↑ after SCK Edge
TscL2ssH
1.5 TCY + 40
Note 1: Requires the use of Parameter #73A.
2: Only if Parameter #71A and #72A are used.
DS39631A-page 352
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-16:
I2C BUS START/STOP BITS TIMING
SCL
SDA
91
93
90
92
Stop
Condition
Start
Condition
Note: Refer to Figure 26-4 for load conditions.
TABLE 26-18: I2C BUS START/STOP BITS REQUIREMENTS (SLAVE MODE)
Param.
Symbol
Characteristic
Min
Max
Units
Conditions
No.
90
TSU:STA Start Condition
Setup Time
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
4700
600
—
—
—
—
—
—
—
—
ns
Only relevant for Repeated
Start condition
91
92
93
THD:STA Start Condition
Hold Time
4000
600
ns
ns
ns
After this period, the first
clock pulse is generated
TSU:STO Stop Condition
Setup Time
4700
600
THD:STO Stop Condition
Hold Time
4000
600
FIGURE 26-17:
I2C BUS DATA TIMING
103
102
100
101
SCL
90
106
107
91
92
SDA
In
110
109
109
SDA
Out
Note: Refer to Figure 26-4 for load conditions.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 353
PIC18F2420/2520/4420/4520
TABLE 26-19: I2C BUS DATA REQUIREMENTS (SLAVE MODE)
Param.
Symbol
Characteristic
Min
Max Units
Conditions
No.
100
THIGH
Clock High Time
100 kHz mode
4.0
—
—
µs
µs
PIC18FXXXX must operate
at a minimum of 1.5 MHz
400 kHz mode
0.6
PIC18FXXXX must operate
at a minimum of 10 MHz
SSP Module
1.5 TCY
4.7
—
—
101
TLOW
Clock Low Time
100 kHz mode
µs
µs
PIC18FXXXX must operate
at a minimum of 1.5 MHz
400 kHz mode
1.3
—
PIC18FXXXX must operate
at a minimum of 10 MHz
SSP Module
1.5 TCY
—
—
102
103
TR
TF
SDA and SCL Rise 100 kHz mode
1000
ns
ns
Time
400 kHz mode
20 + 0.1 CB 300
CB is specified to be from
10 to 400 pF
SDA and SCL Fall 100 kHz mode
Time
—
300
ns
ns
400 kHz mode
20 + 0.1 CB 300
CB is specified to be from
10 to 400 pF
90
TSU:STA Start Condition
Setup Time
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
4.7
0.6
4.0
0.6
0
—
—
µs
µs
µs
µs
ns
µs
ns
ns
µs
µs
ns
ns
µs
µs
Only relevant for Repeated
Start condition
91
THD:STA Start Condition
Hold Time
—
After this period, the first
clock pulse is generated
—
106
107
92
THD:DAT Data Input Hold
Time
—
0
0.9
—
TSU:DAT Data Input Setup
Time
250
100
4.7
0.6
—
(Note 2)
—
TSU:STO Stop Condition
Setup Time
—
—
109
110
TAA
Output Valid from
Clock
3500
—
(Note 1)
—
TBUF
Bus Free Time
4.7
1.3
—
Time the bus must be free
before a new transmission
can start
—
D102
CB
Bus Capacitive Loading
—
400
pF
Note 1: As a transmitter, the device must provide this internal minimum delay time to bridge the undefined region
(min. 300 ns) of the falling edge of SCL to avoid unintended generation of Start or Stop conditions.
2: A fast mode I2C bus device can be used in a standard mode I2C bus system but the requirement,
TSU:DAT ≥ 250 ns, must then be met. This will automatically be the case if the device does not stretch the
LOW period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must
output the next data bit to the SDA line, TR max. + TSU:DAT = 1000 + 250 = 1250 ns (according to the
standard mode I2C bus specification), before the SCL line is released.
DS39631A-page 354
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-18:
MASTER SSP I2C BUS START/STOP BITS TIMING WAVEFORMS
SCL
SDA
93
91
90
92
Stop
Condition
Start
Condition
Note: Refer to Figure 26-4 for load conditions.
TABLE 26-20: MASTER SSP I2C BUS START/STOP BITS REQUIREMENTS
Param.
Symbol
Characteristic
Min
Max Units
Conditions
No.
90
TSU:STA Start Condition
Setup Time
100 kHz mode
400 kHz mode
1 MHz mode(1) 2(TOSC)(BRG + 1)
2(TOSC)(BRG + 1)
2(TOSC)(BRG + 1)
—
—
—
—
—
—
—
—
—
—
—
—
ns Only relevant for
Repeated Start
condition
91
92
93
THD:STA Start Condition
Hold Time
100 kHz mode
400 kHz mode
1 MHz mode(1) 2(TOSC)(BRG + 1)
2(TOSC)(BRG + 1)
ns After this period, the
first clock pulse is
generated
2(TOSC)(BRG + 1)
TSU:STO Stop Condition
Setup Time
100 kHz mode
400 kHz mode
1 MHz mode(1) 2(TOSC)(BRG + 1)
2(TOSC)(BRG + 1)
ns
2(TOSC)(BRG + 1)
THD:STO Stop Condition
Hold Time
100 kHz mode
400 kHz mode
2(TOSC)(BRG + 1)
ns
2(TOSC)(BRG + 1)
1 MHz mode(1) 2(TOSC)(BRG + 1)
Note 1: Maximum pin capacitance = 10 pF for all I2C pins.
FIGURE 26-19:
MASTER SSP I2C BUS DATA TIMING
103
102
100
101
SCL
90
106
91
92
107
SDA
In
110
109
109
SDA
Out
Note: Refer to Figure 26-4 for load conditions.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 355
PIC18F2420/2520/4420/4520
TABLE 26-21: MASTER SSP I2C BUS DATA REQUIREMENTS
Param.
Symbol
Characteristic
Min
Max Units
Conditions
No.
100
THIGH
Clock High Time 100 kHz mode
400 kHz mode
2(TOSC)(BRG + 1)
2(TOSC)(BRG + 1)
—
—
ms
ms
ms
ms
ms
ms
ns
1 MHz mode(1) 2(TOSC)(BRG + 1)
—
101
102
103
90
TLOW
TR
Clock Low Time 100 kHz mode
400 kHz mode
2(TOSC)(BRG + 1)
2(TOSC)(BRG + 1)
—
—
1 MHz mode(1) 2(TOSC)(BRG + 1)
—
SDA and SCL
Rise Time
100 kHz mode
400 kHz mode
1 MHz mode(1)
100 kHz mode
400 kHz mode
1 MHz mode(1)
—
1000
300
300
300
300
100
—
CB is specified to be from
10 to 400 pF
20 + 0.1 CB
ns
—
—
ns
TF
SDA and SCL
Fall Time
ns
CB is specified to be from
10 to 400 pF
20 + 0.1 CB
—
ns
ns
TSU:STA Start Condition 100 kHz mode
2(TOSC)(BRG + 1)
2(TOSC)(BRG + 1)
ms Only relevant for
Setup Time
Repeated Start
400 kHz mode
—
ms
condition
ms
1 MHz mode(1) 2(TOSC)(BRG + 1)
—
91
THD:STA Start Condition 100 kHz mode
2(TOSC)(BRG + 1)
2(TOSC)(BRG + 1)
—
ms After this period, the first
Hold Time
clock pulse is generated
400 kHz mode
—
ms
1 MHz mode(1) 2(TOSC)(BRG + 1)
—
ms
ns
106
107
92
THD:DAT Data Input
Hold Time
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
0
—
0
0.9
—
ms
TSU:DAT Data Input
Setup Time
250
ns
ns
(Note 2)
100
—
TSU:STO Stop Condition
Setup Time
2(TOSC)(BRG + 1)
—
ms
ms
ms
ns
2(TOSC)(BRG + 1)
—
1 MHz mode(1) 2(TOSC)(BRG + 1)
—
109
TAA
Output Valid
from Clock
100 kHz mode
400 kHz mode
1 MHz mode(1)
100 kHz mode
400 kHz mode
—
—
3500
1000
—
ns
—
ns
110
TBUF
CB
Bus Free Time
4.7
1.3
—
ms Time the bus must be free
before a new transmission
—
ms
can start
pF
D102
Bus Capacitive Loading
—
400
Note 1: Maximum pin capacitance = 10 pF for all I2C pins.
2: A fast mode I2C bus device can be used in a standard mode I2C bus system, but parameter 107 ≥ 250 ns
must then be met. This will automatically be the case if the device does not stretch the LOW period of the
SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next data bit
to the SDA line, parameter 102 + parameter 107 = 1000 + 250 = 1250 ns (for 100 kHz mode), before the
SCL line is released.
DS39631A-page 356
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-20:
USART SYNCHRONOUS TRANSMISSION (MASTER/SLAVE) TIMING
RC6/TX/CK
pin
121
121
RC7/RX/DT
pin
120
Note: Refer to Figure 26-4 for load conditions.
122
TABLE 26-22: USART SYNCHRONOUS TRANSMISSION REQUIREMENTS
Param
Symbol
Characteristic
Min
Max
Units Conditions
No.
120
TckH2dtV SYNC XMIT (MASTER & SLAVE)
Clock High to Data Out Valid
PIC18FXXXX
—
—
—
—
—
—
40
100
20
ns
PIC18LFXXXX
ns VDD = 2.0V
ns
121
122
Tckrf
Tdtrf
Clock Out Rise Time and Fall Time PIC18FXXXX
(Master mode)
PIC18LFXXXX
50
ns VDD = 2.0V
ns
Data Out Rise Time and Fall Time
PIC18FXXXX
20
PIC18LFXXXX
50
ns VDD = 2.0V
FIGURE 26-21:
USART SYNCHRONOUS RECEIVE (MASTER/SLAVE) TIMING
RC6/TX/CK
pin
125
RC7/RX/DT
pin
126
Note: Refer to Figure 26-4 for load conditions.
TABLE 26-23: USART SYNCHRONOUS RECEIVE REQUIREMENTS
Param.
Symbol
Characteristic
Min
Max
Units
Conditions
No.
125
TdtV2ckl SYNC RCV (MASTER & SLAVE)
Data Hold before CK ↓ (DT hold time)
Data Hold after CK ↓ (DT hold time)
10
15
—
—
ns
ns
126
TckL2dtl
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 357
PIC18F2420/2520/4420/4520
TABLE 26-24: A/D CONVERTER CHARACTERISTICS: PIC18FX42X/X52X (INDUSTRIAL)
PIC18LFX42X/X52X (INDUSTRIAL)
Param
No.
Symbol
Characteristic
Min
Typ
Max
Units
Conditions
A01
NR
Resolution
—
—
—
—
—
—
10
bit ∆VREF ≥ 3.0V
A03
A04
A06
A07
A10
A20
EIL
Integral Linearity Error
Differential Linearity Error
Offset Error
—
<±1
<±1
<±1
<±1
LSb ∆VREF ≥ 3.0V
LSb ∆VREF ≥ 3.0V
LSb ∆VREF ≥ 3.0V
LSb ∆VREF ≥ 3.0V
EDL
EOFF
EGN
—
—
—
Gain Error
—
Monotonicity
Guaranteed(1)
—
VSS ≤ VAIN ≤ VREF
VDD < 3.0V
VDD ≥ 3.0V
∆VREF Reference Voltage Range
1.8
3
—
—
—
—
V
V
(VREFH – VREFL)
A21
A22
A25
A30
VREFH Reference Voltage High
VSS
—
VREFH
VDD – 3.0V
VREFH
V
V
VREFL
VAIN
Reference Voltage Low
Analog Input Voltage
VSS – 0.3V
VREFL
—
—
—
—
V
ZAIN
Recommended Impedance of
Analog Voltage Source
2.5
kΩ
A50
IREF
VREF Input Current(2)
—
—
—
—
5
150
µA During VAIN acquisition.
µA During A/D conversion
cycle.
Note 1: The A/D conversion result never decreases with an increase in the input voltage and has no missing codes.
2: VREFH current is from RA3/AN3/VREF+ pin or VDD, whichever is selected as the VREFH source.
VREFL current is from RA2/AN2/VREF-/CVREF pin or VSS, whichever is selected as the VREFL source.
DS39631A-page 358
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
FIGURE 26-22:
A/D CONVERSION TIMING
BSF ADCON0, GO
(Note 2)
131
130
Q4
132
A/D CLK
. . .
. . .
9
8
7
2
1
0
A/D DATA
ADRES
NEW_DATA
TCY
OLD_DATA
ADIF
GO
DONE
SAMPLING STOPPED
SAMPLE
Note 1: If the A/D clock source is selected as RC, a time of TCY is added before the A/D clock starts.
This allows the SLEEPinstruction to be executed.
2: This is a minimal RC delay (typically 100 ns), which also disconnects the holding capacitor from the analog input.
TABLE 26-25: A/D CONVERSION REQUIREMENTS
Param
Symbol
Characteristic
Min
Max
Units
Conditions
No.
130
TAD
A/D Clock Period
PIC18FXXXX
0.7
1.4
25.0(1)
25.0(1)
µs TOSC based, VREF ≥ 3.0V
PIC18LFXXXX
µs VDD = 2.0V;
TOSC based, VREF full range
PIC18FXXXX
TBD
TBD
11
1
3
µs A/D RC mode
µs VDD = 2.0V; A/D RC mode
TAD
PIC18LFXXXX
131
132
TCNV
TACQ
Conversion Time
(not including acquisition time) (Note 2)
Acquisition Time (Note 3)
12
1.4
TBD
—
—
µs -40°C to +85°C
µs
0°C ≤ to ≤ +85°C
135
TSWC
TDIS
Switching Time from Convert → Sample
—
(Note 4)
TBD
Discharge Time
0.2
—
µs
Legend: TBD = To Be Determined
Note 1: The time of the A/D clock period is dependent on the device frequency and the TAD clock divider.
2: ADRES register may be read on the following TCY cycle.
3: The time for the holding capacitor to acquire the “New” input voltage when the voltage changes full scale
after the conversion (VDD to VSS or VSS to VDD). The source impedance (RS) on the input channels is 50Ω.
4: On the following cycle of the device clock.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 359
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 360
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
27.0 DC AND AC
CHARACTERISTICS GRAPHS
AND TABLES
Graphs and tables are not available at this time.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 361
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 362
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
28.0 PACKAGING INFORMATION
28.1 Package Marking Information
28-Lead PDIP
Example
PIC18F2520-I/SP
0410017
XXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXX
YYWWNNN
28-Lead SOIC
Example
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
PIC18F2520-E/SO
0410017
YYWWNNN
40-Lead PDIP
Example
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
YYWWNNN
PIC18F4420-I/P
0410017
Legend: XX...X Customer specific information*
Y
YY
Year code (last digit of calendar year)
Year code (last 2 digits of calendar year)
WW
NNN
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
Note: In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line thus limiting the number of available characters
for customer specific information.
*
Standard PICmicro device marking consists of Microchip part number, year code, week code and
traceability code. For PICmicro device marking beyond this, certain price adders apply. Please check
with your Microchip Sales Office. For QTP devices, any special marking adders are included in QTP
price.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 363
PIC18F2420/2520/4420/4520
Package Marking Information (Continued)
28-Lead QFN
Example
XXXXXXXX
XXXXXXXX
YYWWNNN
18F2420
-I/ML
0410017
44-Lead QFN
Example
XXXXXXXXXX
XXXXXXXXXX
XXXXXXXXXX
YYWWNNN
PIC18F4520
-I/ML
0410017
44-Lead TQFP
Example
XXXXXXXXXX
XXXXXXXXXX
XXXXXXXXXX
YYWWNNN
PIC18F4420
-I/PT
0410017
DS39631A-page 364
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
28.2 Package Details
The following sections give the technical details of the packages.
28-Lead Skinny Plastic Dual In-line (SP) – 300 mil Body (PDIP)
E1
D
2
n
1
α
E
A2
L
A
c
B1
β
A1
eB
p
B
Units
INCHES*
NOM
MILLIMETERS
Dimension Limits
MIN
MAX
MIN
NOM
28
MAX
n
p
Number of Pins
Pitch
28
.100
.150
.130
2.54
3.81
3.30
Top to Seating Plane
Molded Package Thickness
Base to Seating Plane
Shoulder to Shoulder Width
Molded Package Width
Overall Length
A
A2
A1
E
.140
.160
3.56
4.06
.125
.015
.300
.275
1.345
.125
.008
.040
.016
.320
.135
3.18
0.38
7.62
6.99
34.16
3.18
0.20
1.02
3.43
.310
.285
1.365
.130
.012
.053
.019
.350
10
.325
.295
1.385
.135
.015
.065
.022
.430
15
7.87
7.24
8.26
7.49
35.18
3.43
0.38
1.65
0.56
10.92
15
E1
D
34.67
3.30
Tip to Seating Plane
Lead Thickness
L
c
0.29
Upper Lead Width
B1
B
1.33
Lower Lead Width
0.41
8.13
5
0.48
8.89
10
Overall Row Spacing
Mold Draft Angle Top
Mold Draft Angle Bottom
§
eB
α
5
β
5
10
15
5
10
15
* Controlling Parameter
§ Significant Characteristic
Notes:
Dimension D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed
.010” (0.254mm) per side.
JEDEC Equivalent: MO-095
Drawing No. C04-070
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 365
PIC18F2420/2520/4420/4520
28-Lead Plastic Small Outline (SO) – Wide, 300 mil Body (SOIC)
E
E1
p
D
B
2
n
1
h
α
45°
c
A2
A
φ
β
L
A1
Units
INCHES*
NOM
MILLIMETERS
NOM
Dimension Limits
MIN
MAX
MIN
MAX
n
p
Number of Pins
Pitch
28
28
.050
.099
.091
.008
.407
.295
.704
.020
.033
4
1.27
2.50
2.31
0.20
10.34
7.49
17.87
0.50
0.84
4
Overall Height
A
.093
.104
2.36
2.64
Molded Package Thickness
Standoff
A2
A1
E
.088
.004
.394
.288
.695
.010
.016
0
.094
.012
.420
.299
.712
.029
.050
8
2.24
0.10
10.01
7.32
17.65
0.25
0.41
0
2.39
0.30
10.67
7.59
18.08
0.74
1.27
8
§
Overall Width
Molded Package Width
Overall Length
E1
D
Chamfer Distance
Foot Length
h
L
φ
Foot Angle Top
c
Lead Thickness
Lead Width
.009
.014
0
.011
.017
12
.013
.020
15
0.23
0.36
0
0.28
0.42
12
0.33
0.51
15
B
α
β
Mold Draft Angle Top
Mold Draft Angle Bottom
0
12
15
0
12
15
* Controlling Parameter
§ Significant Characteristic
Notes:
Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed
.010” (0.254mm) per side.
JEDEC Equivalent: MS-013
Drawing No. C04-052
DS39631A-page 366
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
40-Lead Plastic Dual In-line (P) – 600 mil Body (PDIP)
E1
D
2
1
α
n
E
A2
A
L
c
B1
B
β
A1
p
eB
Units
INCHES*
NOM
MILLIMETERS
Dimension Limits
MIN
MAX
MIN
NOM
40
MAX
n
p
Number of Pins
Pitch
40
.100
.175
.150
2.54
Top to Seating Plane
A
.160
.190
.160
4.06
3.56
4.45
3.81
4.83
4.06
Molded Package Thickness
Base to Seating Plane
Shoulder to Shoulder Width
Molded Package Width
Overall Length
A2
A1
E
.140
.015
.595
.530
2.045
.120
.008
.030
.014
.620
5
0.38
15.11
13.46
51.94
3.05
0.20
0.76
0.36
15.75
5
.600
.545
2.058
.130
.012
.050
.018
.650
10
.625
.560
2.065
.135
.015
.070
.022
.680
15
15.24
13.84
52.26
3.30
0.29
1.27
0.46
16.51
10
15.88
14.22
52.45
3.43
0.38
1.78
0.56
17.27
15
E1
D
Tip to Seating Plane
Lead Thickness
L
c
Upper Lead Width
B1
B
Lower Lead Width
Overall Row Spacing
Mold Draft Angle Top
§
eB
α
β
Mold Draft Angle Bottom
* Controlling Parameter
§ Significant Characteristic
5
10
15
5
10
15
Notes:
Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed
.010” (0.254mm) per side.
JEDEC Equivalent: MO-011
Drawing No. C04-016
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 367
PIC18F2420/2520/4420/4520
28-Lead Plastic Quad Flat No Lead Package (ML) 6x6 mm Body, Saw Singulated (QFN)
E
E2
EXPOSED
METAL
PAD
p
D
D2
2
1
B
n
ALTERNATE
INDEX
OPTIONAL
SEE DETAIL
L
INDEX
AREA
TOP VIEW
INDICATORS
BOTTOM VIEW
A1
A
DETAIL
ALTERNATE
PAD OUTLINE
Units
INCHES
MILLIMETERS*
NOM
Dimension Limits
MIN
NOM
MAX
MIN
MAX
n
p
Number of Pins
Pitch
28
28
.026 BSC
.035
0.65 BSC
Overall Height
Standoff
A
A1
E
.031
.039
.002
.240
.152
.240
.152
.013
.024
0.80
0.00
0.90
0.02
6.00
3.70
6.00
3.70
0.28
0.55
1.00
0.05
6.10
3.85
6.10
3.85
0.33
0.60
.000
.232
.140
.232
.140
.009
.020
.001
Overall Width
Exposed Pad Width
Overall Length
Exposed Pad Length
Lead Width
.236
5.90
3.55
5.90
3.55
0.23
0.50
E2
D
.146
.236
D2
B
.146
.011
Lead Length
L
.022
*Controlling Parameter
Notes:
JEDEC equivalent: MO-220
Drawing No. C04-105
DS39631A-page 368
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
44-Lead Plastic Quad Flat No Lead Package (ML) 8x8 mm Body (QFN)
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 369
PIC18F2420/2520/4420/4520
44-Lead Plastic Thin Quad Flatpack (PT) 10x10x1 mm Body, 1.0/0.10 mm Lead Form (TQFP)
E
E1
#leads=n1
p
D1
D
2
1
B
n
°
CH x 45
α
A
c
φ
β
A1
A2
L
(F)
Units
INCHES
NOM
MILLIMETERS*
Dimension Limits
MIN
MAX
MIN
NOM
44
MAX
n
p
Number of Pins
Pitch
44
.031
11
0.80
11
Pins per Side
Overall Height
n1
A
.039
.037
.002
.018
.043
.039
.004
.024
.039
3.5
.047
1.00
0.95
1.10
1.00
0.10
0.60
1.20
Molded Package Thickness
Standoff
A2
A1
L
(F)
φ
.041
.006
.030
1.05
0.15
0.75
§
0.05
0.45
1.00
0
Foot Length
Footprint (Reference)
Foot Angle
0
.463
.463
.390
.390
.004
.012
.025
5
7
.482
.482
.398
.398
.008
.017
.045
15
3.5
12.00
12.00
10.00
10.00
0.15
0.38
0.89
10
7
12.25
12.25
10.10
10.10
0.20
0.44
1.14
15
Overall Width
E
D
.472
.472
.394
.394
.006
.015
.035
10
11.75
11.75
9.90
9.90
0.09
0.30
0.64
5
Overall Length
Molded Package Width
Molded Package Length
Lead Thickness
E1
D1
c
Lead Width
B
CH
α
Pin 1 Corner Chamfer
Mold Draft Angle Top
Mold Draft Angle Bottom
β
5
10
15
5
10
15
* Controlling Parameter
§ Significant Characteristic
Notes:
Dimensions D1 and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed
.010” (0.254mm) per side.
JEDEC Equivalent: MS-026
Drawing No. C04-076
DS39631A-page 370
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
APPENDIX A: REVISION HISTORY
APPENDIX B: DEVICE
DIFFERENCES
Revision A (June 2004)
The differences between the devices listed in this data
sheet are shown in Table B-1.
Original data sheet for PIC18F2420/2520/4420/4520
devices.
TABLE B-1:
DEVICE DIFFERENCES
Features
PIC18F2420
PIC18F2520
PIC18F4420
PIC18F4520
16384
32768
16384
19
16384
8192
20
32768
16384
20
Program Memory (Bytes)
Program Memory (Instructions)
Interrupt Sources
8192
19
I/O Ports
Ports A, B, C, (E)
Ports A, B, C, (E) Ports A, B, C, D, E Ports A, B, C, D, E
Capture/Compare/PWM Modules
2
0
2
0
1
1
1
1
Enhanced
Capture/Compare/PWM Modules
Parallel Communications (PSP)
10-bit Analog-to-Digital Module
Packages
No
No
Yes
Yes
10 input channels 10 input channels
13 input channels
13 input channels
28-pin PDIP
28-pin SOIC
28-pin QFN
28-pin PDIP
28-pin SOIC
28-pin QFN
40-pin PDIP
44-pin TQFP
44-pin QFN
40-pin PDIP
44-pin TQFP
44-pin QFN
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 371
PIC18F2420/2520/4420/4520
APPENDIX C: CONVERSION
CONSIDERATIONS
APPENDIX D: MIGRATION FROM
BASELINE TO
ENHANCED DEVICES
This appendix discusses the considerations for
converting from previous versions of a device to the
ones listed in this data sheet. Typically, these changes
are due to the differences in the process technology
used. An example of this type of conversion is from a
PIC16C74A to a PIC16C74B.
This section discusses how to migrate from a Baseline
device (i.e., PIC16C5X) to an Enhanced MCU device
(i.e., PIC18FXXX).
The following are the list of modifications over the
PIC16C5X microcontroller family:
Not Applicable
Not Currently Available
DS39631A-page 372
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
APPENDIX E: MIGRATION FROM
APPENDIX F: MIGRATION FROM
HIGH-END TO
MID-RANGE TO
ENHANCED DEVICES
ENHANCED DEVICES
A detailed discussion of the differences between the
mid-range MCU devices (i.e., PIC16CXXX) and the
enhanced devices (i.e., PIC18FXXX) is provided in
AN716, “Migrating Designs from PIC16C74A/74B to
PIC18C442”. The changes discussed, while device
specific, are generally applicable to all mid-range to
enhanced device migrations.
A detailed discussion of the migration pathway and dif-
ferences between the high-end MCU devices (i.e.,
PIC17CXXX) and the enhanced devices (i.e.,
PIC18FXXX) is provided in AN726, “PIC17CXXX to
PIC18CXXX Migration”. This Application Note is
available as Literature Number DS00726.
This Application Note is available as Literature Number
DS00716.
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 373
PIC18F2420/2520/4420/4520
NOTES:
DS39631A-page 374
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
INDEX
Block Diagrams
A
A/D ........................................................................... 226
A/D ................................................................................... 223
A/D Converter Interrupt, Configuring ....................... 227
Acquisition Requirements ........................................ 228
ADCON0 Register .................................................... 223
ADCON1 Register .................................................... 223
ADCON2 Register .................................................... 223
ADRESH Register ............................................ 223, 226
ADRESL Register .................................................... 223
Analog Port Pins, Configuring .................................. 230
Associated Registers ............................................... 232
Calculating the Minimum Required
Acquisition Time .............................................. 228
Configuring the Module ............................................ 227
Conversion Clock (TAD) ........................................... 229
Conversion Status (GO/DONE Bit) .......................... 226
Conversions ............................................................. 231
Converter Characteristics ........................................ 358
Discharge ................................................................. 231
Operation in Power Managed Modes ...................... 230
Selecting and Configuring Acquisition Time ............ 229
Special Event Trigger (CCP) .................................... 232
Special Event Trigger (ECCP) ................................. 148
Use of the CCP2 Trigger .......................................... 232
Absolute Maximum Ratings ............................................. 323
AC (Timing) Characteristics ............................................. 340
Load Conditions for Device
Analog Input Model .................................................. 227
Baud Rate Generator .............................................. 187
Capture Mode Operation ......................................... 141
Comparator Analog Input Model .............................. 237
Comparator I/O Operating Modes ........................... 234
Comparator Output .................................................. 236
Comparator Voltage Reference ............................... 240
Compare Mode Operation ....................................... 142
Device Clock .............................................................. 28
Enhanced PWM ....................................................... 149
EUSART Receive .................................................... 213
EUSART Transmit ................................................... 211
External Power-on Reset Circuit
(Slow VDD Power-up) ........................................ 43
Fail-Safe Clock Monitor (FSCM) .............................. 261
Generic I/O Port ....................................................... 105
High/Low-Voltage Detect with External Input .......... 244
Interrupt Logic ............................................................ 92
2
MSSP (I C Master Mode) ........................................ 185
2
MSSP (I C Mode) .................................................... 170
MSSP (SPI Mode) ................................................... 161
On-Chip Reset Circuit ................................................ 41
PIC18F2420/2520 ..................................................... 10
PIC18F4420/4520 ..................................................... 11
PLL (HS Mode) .......................................................... 25
PORTD and PORTE (Parallel Slave Port) ............... 120
PWM Operation (Simplified) .................................... 144
Reads from Flash Program Memory ......................... 77
Single Comparator ................................................... 235
Table Read Operation ............................................... 73
Table Write Operation ............................................... 74
Table Writes to Flash Program Memory .................... 79
Timer0 in 16-Bit Mode ............................................. 124
Timer0 in 8-Bit Mode ............................................... 124
Timer1 ..................................................................... 128
Timer1 (16-Bit Read/Write Mode) ............................ 128
Timer2 ..................................................................... 134
Timer3 ..................................................................... 136
Timer3 (16-Bit Read/Write Mode) ............................ 136
Voltage Reference Output Buffer Example ............. 241
Watchdog Timer ...................................................... 258
BN .................................................................................... 276
BNC ................................................................................. 277
BNN ................................................................................. 277
BNOV .............................................................................. 278
BNZ ................................................................................. 278
BOR. See Brown-out Reset.
BOV ................................................................................. 281
BRA ................................................................................. 279
Break Character (12-Bit) Transmit and Receive .............. 216
BRG. See Baud Rate Generator.
Brown-out Reset (BOR) ..................................................... 44
Detecting ................................................................... 44
Disabling in Sleep Mode ............................................ 44
Software Enabled ...................................................... 44
BSF .................................................................................. 279
BTFSC ............................................................................. 280
BTFSS ............................................................................. 280
BTG ................................................................................. 281
BZ .................................................................................... 282
Timing Specifications ....................................... 341
Parameter Symbology ............................................. 340
Temperature and Voltage Specifications ................. 341
Timing Conditions .................................................... 341
AC Characteristics
Internal RC Accuracy ............................................... 343
Access Bank
Mapping with Indexed Literal Offset Mode ................. 72
ACKSTAT ........................................................................ 191
ACKSTAT Status Flag ..................................................... 191
ADCON0 Register ............................................................ 223
GO/DONE Bit ........................................................... 226
ADCON1 Register ............................................................ 223
ADCON2 Register ............................................................ 223
ADDFSR .......................................................................... 310
ADDLW ............................................................................ 273
ADDULNK ........................................................................ 310
ADDWF ............................................................................ 273
ADDWFC ......................................................................... 274
ADRESH Register ............................................................ 223
ADRESL Register .................................................... 223, 226
Analog-to-Digital Converter. See A/D.
ANDLW ............................................................................ 274
ANDWF ............................................................................ 275
Assembler
MPASM Assembler .................................................. 317
Auto-Wake-up on Sync Break Character ......................... 214
B
Bank Select Register (BSR) ............................................... 59
Baud Rate Generator ....................................................... 187
BC .................................................................................... 275
BCF .................................................................................. 276
BF .................................................................................... 191
BF Status Flag ................................................................. 191
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 375
PIC18F2420/2520/4420/4520
Reference ................................................................ 235
C
External Signal ................................................ 235
Internal Signal .................................................. 235
C Compilers
MPLAB C17 .............................................................318
Response Time ........................................................ 235
Comparator Specifications ............................................... 338
Comparator Voltage Reference ....................................... 239
Accuracy and Error .................................................. 240
Associated Registers ............................................... 241
Configuring .............................................................. 239
Connection Considerations ...................................... 240
Effects of a Reset .................................................... 240
Operation During Sleep ........................................... 240
Compare (CCP Module) .................................................. 142
Associated Registers ............................................... 143
CCPRx Register ...................................................... 142
Pin Configuration ..................................................... 142
Software Interrupt .................................................... 142
Special Event Trigger .............................. 137, 142, 232
Timer1/Timer3 Mode Selection ................................ 142
Compare (ECCP Module) ................................................ 148
Special Event Trigger .............................................. 148
Computed GOTO ............................................................... 56
Configuration Bits ............................................................ 249
Configuration Register Protection .................................... 266
Context Saving During Interrupts ..................................... 103
Conversion Considerations .............................................. 372
CPFSEQ .......................................................................... 284
CPFSGT .......................................................................... 285
CPFSLT ........................................................................... 285
Crystal Oscillator/Ceramic Resonator ................................ 23
MPLAB C18 .............................................................318
MPLAB C30 .............................................................318
CALL ................................................................................282
CALLW .............................................................................311
Capture (CCP Module) .....................................................141
Associated Registers ...............................................143
CCP Pin Configuration .............................................141
CCPRxH:CCPRxL Registers ...................................141
Prescaler ..................................................................141
Software Interrupt ....................................................141
Timer1/Timer3 Mode Selection ................................141
Capture (ECCP Module) ..................................................148
Capture/Compare/PWM (CCP) ........................................139
Capture Mode. See Capture.
CCP Mode and Timer Resources ............................140
CCPRxH Register ....................................................140
CCPRxL Register .....................................................140
Compare Mode. See Compare.
Interaction of Two CCP Modules .............................140
Module Configuration ...............................................140
Clock Sources ....................................................................28
Selecting the 31 kHz Source ......................................29
Selection Using OSCCON Register ...........................29
CLRF ................................................................................283
CLRWDT ..........................................................................283
Code Examples
16 x 16 Signed Multiply Routine ................................90
16 x 16 Unsigned Multiply Routine ............................90
8 x 8 Signed Multiply Routine ....................................89
8 x 8 Unsigned Multiply Routine ................................89
Changing Between Capture Prescalers ...................141
Computed GOTO Using an Offset Value ...................56
Data EEPROM Read .................................................85
Data EEPROM Refresh Routine ................................86
Data EEPROM Write .................................................85
Erasing a Flash Program Memory Row .....................78
Fast Register Stack ....................................................56
How to Clear RAM (Bank 1) Using
D
Data Addressing Modes .................................................... 68
Comparing Addressing Modes with the
Extended Instruction Set Enabled ..................... 71
Direct ......................................................................... 68
Indexed Literal Offset ................................................ 70
Instructions Affected .......................................... 70
Indirect ....................................................................... 68
Inherent and Literal .................................................... 68
Data EEPROM
Code Protection ....................................................... 266
Data EEPROM Memory ..................................................... 83
Associated Registers ................................................. 87
EEADR Register ........................................................ 83
EECON1 and EECON2 Registers ............................. 83
Operation During Code-Protect ................................. 86
Protection Against Spurious Write ............................. 86
Reading ..................................................................... 85
Using ......................................................................... 86
Write Verify ................................................................ 85
Writing ....................................................................... 85
Data Memory ..................................................................... 59
Access Bank .............................................................. 62
and the Extended Instruction Set .............................. 70
Bank Select Register (BSR) ...................................... 59
General Purpose Registers ....................................... 62
Map for PIC18F2420/4420 ........................................ 60
Map for PIC18F2520/4520 ........................................ 61
Special Function Registers ........................................ 63
DAW ................................................................................ 286
DC and AC Characteristics
Indirect Addressing ............................................68
Implementing a Real-Time Clock Using
a Timer1 Interrupt Service ...............................131
Initializing PORTA ....................................................105
Initializing PORTB ....................................................108
Initializing PORTC ....................................................111
Initializing PORTD ....................................................114
Initializing PORTE ....................................................117
Loading the SSPBUF (SSPSR) Register .................164
Reading a Flash Program Memory Word ..................77
Saving Status, WREG and
BSR Registers in RAM .....................................103
Writing to Flash Program Memory ....................... 80–81
Code Protection ...............................................................249
COMF ...............................................................................284
Comparator ......................................................................233
Analog Input Connection Considerations .................237
Associated Registers ...............................................237
Configuration ............................................................234
Effects of a Reset .....................................................236
Interrupts ..................................................................236
Operation .................................................................235
Operation During Sleep ...........................................236
Outputs ....................................................................235
Graphs and Tables .................................................. 361
DS39631A-page 376
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
DC Characteristics ........................................................... 335
Baud Rate Generator (BRG) ................................... 205
Associated Registers ....................................... 206
Auto-Baud Rate Detect .................................... 209
Baud Rate Error, Calculating ........................... 206
Baud Rates, Asynchronous Modes ................. 207
High Baud Rate Select (BRGH Bit) ................. 205
Sampling ......................................................... 205
Synchronous Master Mode ...................................... 217
Associated Registers, Receive ........................ 219
Associated Registers, Transmit ....................... 218
Reception ........................................................ 219
Transmission ................................................... 217
Synchronous Slave Mode ........................................ 220
Associated Registers, Receive ........................ 221
Associated Registers, Transmit ....................... 220
Reception ........................................................ 221
Transmission ................................................... 220
Evaluation and Programming Tools ................................. 321
Extended Instruction Set
ADDFSR .................................................................. 310
ADDULNK ............................................................... 310
and Using MPLAB Tools ......................................... 316
CALLW .................................................................... 311
Considerations for Use ............................................ 314
MOVSF .................................................................... 311
MOVSS .................................................................... 312
PUSHL ..................................................................... 312
SUBFSR .................................................................. 313
SUBULNK ................................................................ 313
Syntax ...................................................................... 309
External Clock Input ........................................................... 24
Power-Down and Supply Current ............................ 326
Supply Voltage ......................................................... 325
DCFSNZ .......................................................................... 287
DECF ............................................................................... 286
DECFSZ ........................................................................... 287
Demonstration Boards
PICDEM 1 ................................................................ 320
PICDEM 17 .............................................................. 321
PICDEM 18R ........................................................... 321
PICDEM 2 Plus ........................................................ 320
PICDEM 3 ................................................................ 320
PICDEM 4 ................................................................ 320
PICDEM LIN ............................................................ 321
PICDEM USB ........................................................... 321
PICDEM.net Internet/Ethernet ................................. 320
Development Support ...................................................... 317
Device Differences ........................................................... 371
Device Overview .................................................................. 7
Details on Individual Family Members ......................... 8
Features (table) ............................................................ 9
New Core Features ...................................................... 7
Other Special Features ................................................ 8
Device Reset Timers .......................................................... 45
Oscillator Start-up Timer (OST) ................................. 45
PLL Lock Time-out ..................................................... 45
Power-up Timer (PWRT) ........................................... 45
Time-out Sequence .................................................... 45
Direct Addressing ............................................................... 69
E
Effect on Standard PIC Instructions ................................. 314
Effects of Power Managed Modes on
F
Various Clock Sources ............................................... 31
Electrical Characteristics .................................................. 323
Enhanced Capture/Compare/PWM (ECCP) .................... 147
Associated Registers ............................................... 160
Capture and Compare Modes .................................. 148
Capture Mode. See Capture (ECCP Module).
Outputs and Configuration ....................................... 148
Pin Configurations for ECCP1 ................................. 148
PWM Mode. See PWM (ECCP Module).
Standard PWM Mode ............................................... 148
Timer Resources ...................................................... 148
Enhanced PWM Mode. See PWM (ECCP Module).
Enhanced Universal Synchronous Asynchronous
Receiver Transmitter (EUSART). See EUSART.
Equations
Fail-Safe Clock Monitor ........................................... 249, 261
Exiting Operation ..................................................... 261
Interrupts in Power Managed Modes ....................... 262
POR or Wake from Sleep ........................................ 262
WDT During Oscillator Failure ................................. 261
Fast Register Stack ........................................................... 56
Firmware Instructions ...................................................... 267
Flash Program Memory ..................................................... 73
Associated Registers ................................................. 81
Control Registers ....................................................... 74
EECON1 and EECON2 ..................................... 74
TABLAT (Table Latch) Register ........................ 76
TBLPTR (Table Pointer) Register ...................... 76
Erase Sequence ........................................................ 78
Erasing ...................................................................... 78
Operation During Code-Protect ................................. 81
Reading ..................................................................... 77
Table Pointer
Boundaries Based on Operation ....................... 76
Table Pointer Boundaries .......................................... 76
Table Reads and Table Writes .................................. 73
Write Sequence ......................................................... 79
Writing To .................................................................. 79
Protection Against Spurious Writes ................... 81
Unexpected Termination ................................... 81
Write Verify ........................................................ 81
FSCM. See Fail-Safe Clock Monitor.
A/D Acquisition Time ................................................ 228
A/D Minimum Charging Time ................................... 228
Errata ................................................................................... 6
EUSART
Asynchronous Mode ................................................ 211
12-Bit Break Transmit and Receive ................. 216
Associated Registers, Receive ........................ 214
Associated Registers, Transmit ....................... 212
Auto-Wake-up on Sync Break ......................... 214
Receiver ........................................................... 213
Setting up 9-Bit Mode with
Address Detect ........................................ 213
Transmitter ....................................................... 211
Baud Rate Generator
G
General Call Address Support ......................................... 184
GOTO .............................................................................. 288
Operation in Power Managed Mode ................ 205
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 377
PIC18F2420/2520/4420/4520
Initialization Conditions for all Registers ...................... 49–52
H
Instruction Cycle ................................................................ 57
Clocking Scheme ....................................................... 57
Instruction Flow/Pipelining ................................................. 57
Instruction Set .................................................................. 267
ADDLW .................................................................... 273
ADDWF .................................................................... 273
ADDWF (Indexed Literal Offset Mode) .................... 315
ADDWFC ................................................................. 274
ANDLW .................................................................... 274
ANDWF .................................................................... 275
BC ............................................................................ 275
BCF ......................................................................... 276
BN ............................................................................ 276
BNC ......................................................................... 277
BNN ......................................................................... 277
BNOV ...................................................................... 278
BNZ ......................................................................... 278
BOV ......................................................................... 281
BRA ......................................................................... 279
BSF .......................................................................... 279
BSF (Indexed Literal Offset Mode) .......................... 315
BTFSC ..................................................................... 280
BTFSS ..................................................................... 280
BTG ......................................................................... 281
BZ ............................................................................ 282
CALL ........................................................................ 282
CLRF ....................................................................... 283
CLRWDT ................................................................. 283
COMF ...................................................................... 284
CPFSEQ .................................................................. 284
CPFSGT .................................................................. 285
CPFSLT ................................................................... 285
DAW ........................................................................ 286
DCFSNZ .................................................................. 287
DECF ....................................................................... 286
DECFSZ .................................................................. 287
Extended Instruction Set ......................................... 309
General Format ........................................................ 269
GOTO ...................................................................... 288
INCF ........................................................................ 288
INCFSZ .................................................................... 289
INFSNZ .................................................................... 289
IORLW ..................................................................... 290
IORWF ..................................................................... 290
LFSR ....................................................................... 291
MOVF ...................................................................... 291
MOVFF .................................................................... 292
MOVLB .................................................................... 292
MOVLW ................................................................... 293
MOVWF ................................................................... 293
MULLW .................................................................... 294
MULWF .................................................................... 294
NEGF ....................................................................... 295
NOP ......................................................................... 295
Opcode Field Descriptions ....................................... 268
POP ......................................................................... 296
PUSH ....................................................................... 296
RCALL ..................................................................... 297
RESET ..................................................................... 297
RETFIE .................................................................... 298
RETLW .................................................................... 298
RETURN .................................................................. 299
RLCF ....................................................................... 299
RLNCF ..................................................................... 300
Hardware Multiplier ............................................................89
Introduction ................................................................89
Operation ...................................................................89
Performance Comparison ..........................................89
High/Low-Voltage Detect .................................................243
Applications ..............................................................246
Associated Registers ...............................................247
Characteristics .........................................................339
Current Consumption ...............................................245
Effects of a Reset .....................................................247
Operation .................................................................244
During Sleep ....................................................247
Setup ........................................................................245
Start-up Time ...........................................................245
Typical Application ...................................................246
HLVD. See High/Low-Voltage Detect.
I
I/O Ports ...........................................................................105
2
I C Mode (MSSP)
Acknowledge Sequence Timing ...............................194
Baud Rate Generator ...............................................187
Bus Collision
During a Repeated Start Condition ..................198
During a Stop Condition ...................................199
Clock Arbitration .......................................................188
Clock Stretching .......................................................180
10-Bit Slave Receive Mode (SEN = 1) .............180
10-Bit Slave Transmit Mode .............................180
7-Bit Slave Receive Mode (SEN = 1) ...............180
7-Bit Slave Transmit Mode ...............................180
Clock Synchronization and the CKP Bit (SEN = 1) ..181
Effects of a Reset .....................................................195
General Call Address Support .................................184
2
I C Clock Rate w/BRG .............................................187
Master Mode ............................................................185
Operation .........................................................186
Reception .........................................................191
Repeated Start Condition Timing .....................190
Start Condition Timing .....................................189
Transmission ....................................................191
Multi-Master Communication, Bus Collision
and Arbitration ..................................................195
Multi-Master Mode ...................................................195
Operation .................................................................174
Read/Write Bit Information (R/W Bit) ............... 174, 175
Registers ..................................................................170
Serial Clock (RC3/SCK/SCL) ...................................175
Slave Mode ..............................................................174
Addressing .......................................................174
Reception .........................................................175
Transmission ....................................................175
Sleep Operation .......................................................195
Stop Condition Timing ..............................................194
ID Locations ............................................................. 249, 266
INCF .................................................................................288
INCFSZ ............................................................................289
In-Circuit Debugger ..........................................................266
In-Circuit Serial Programming (ICSP) ......................249, 266
Indexed Literal Offset Addressing
and Standard PIC18 Instructions .............................314
Indexed Literal Offset Mode .............................................314
Indirect Addressing ............................................................69
INFSNZ ............................................................................289
DS39631A-page 378
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
RRCF ....................................................................... 300
MOVLB ............................................................................ 292
MOVLW ........................................................................... 293
MOVSF ............................................................................ 311
MOVSS ............................................................................ 312
MOVWF ........................................................................... 293
MPLAB ASM30 Assembler, Linker, Librarian .................. 318
MPLAB ICD 2 In-Circuit Debugger .................................. 319
MPLAB ICE 2000 High-Performance
Universal In-Circuit Emulator ................................... 319
MPLAB ICE 4000 High-Performance
Universal In-Circuit Emulator ................................... 319
MPLAB Integrated Development
RRNCF .................................................................... 301
SETF ........................................................................ 301
SETF (Indexed Literal Offset Mode) ........................ 315
SLEEP ..................................................................... 302
SUBFWB .................................................................. 302
SUBLW .................................................................... 303
SUBWF .................................................................... 303
SUBWFB .................................................................. 304
SWAPF .................................................................... 304
TBLRD ..................................................................... 305
TBLWT ..................................................................... 306
TSTFSZ ................................................................... 307
XORLW .................................................................... 307
XORWF .................................................................... 308
INTCON Registers ....................................................... 93–95
Environment Software ............................................. 317
MPLAB PM3 Device Programmer ................................... 319
MPLINK Object Linker/MPLIB Object Librarian ............... 318
MSSP
2
Inter-Integrated Circuit. See I C.
ACK Pulse ....................................................... 174, 175
Control Registers (general) ..................................... 161
Internal Oscillator Block ..................................................... 26
Adjustment ................................................................. 26
INTIO Modes .............................................................. 26
INTOSC Frequency Drift ............................................ 26
INTOSC Output Frequency ........................................ 26
OSCTUNE Register ................................................... 26
PLL in INTOSC Modes .............................................. 26
Internal RC Oscillator
Use with WDT .......................................................... 258
Interrupt Sources ............................................................. 249
A/D Conversion Complete ....................................... 227
Capture Complete (CCP) ......................................... 141
Compare Complete (CCP) ....................................... 142
Interrupt-on-Change (RB7:RB4) .............................. 108
INTn Pin ................................................................... 103
PORTB, Interrupt-on-Change .................................. 103
TMR0 ....................................................................... 103
TMR0 Overflow ........................................................ 125
TMR1 Overflow ........................................................ 127
TMR2 to PR2 Match (PWM) ............................ 144, 149
TMR3 Overflow ................................................ 135, 137
Interrupts ............................................................................ 91
Interrupts, Flag Bits
2
2
I C Mode. See I C Mode.
Module Overview ..................................................... 161
SPI Master/Slave Connection .................................. 165
SPI Mode. See SPI Mode.
SSPBUF Register .................................................... 166
SSPSR Register ...................................................... 166
MULLW ............................................................................ 294
MULWF ............................................................................ 294
N
NEGF ............................................................................... 295
NOP ................................................................................. 295
O
Oscillator Configuration ..................................................... 23
EC .............................................................................. 23
ECIO .......................................................................... 23
HS .............................................................................. 23
HSPLL ....................................................................... 23
Internal Oscillator Block ............................................. 26
INTIO1 ....................................................................... 23
INTIO2 ....................................................................... 23
LP .............................................................................. 23
RC ............................................................................. 23
RCIO .......................................................................... 23
XT .............................................................................. 23
Oscillator Selection .......................................................... 249
Oscillator Start-up Timer (OST) ................................... 31, 45
Oscillator Switching ........................................................... 28
Oscillator Transitions ......................................................... 29
Oscillator, Timer1 ..................................................... 127, 137
Oscillator, Timer3 ............................................................. 135
Interrupt-on-Change (RB7:RB4) Flag
(RBIF Bit) ......................................................... 108
INTOSC, INTRC. See Internal Oscillator Block.
IORLW ............................................................................. 290
IORWF ............................................................................. 290
IPR Registers ................................................................... 100
L
LFSR ................................................................................ 291
Low-Voltage ICSP Programming.
See Single-Supply ICSP Programming
P
M
Packaging Information ..................................................... 363
Marking .................................................................... 363
Parallel Slave Port (PSP) ......................................... 114, 120
Associated Registers ............................................... 121
CS (Chip Select) ...................................................... 120
PORTD .................................................................... 120
RD (Read Input) ...................................................... 120
Select (PSPMODE Bit) .................................... 114, 120
WR (Write Input) ...................................................... 120
PICkit 1 Flash Starter Kit ................................................. 321
PICSTART Plus Development Programmer .................... 320
PIE Registers ..................................................................... 98
Master Clear (MCLR) ......................................................... 43
Master Synchronous Serial Port (MSSP). See MSSP.
Memory Organization ......................................................... 53
Data Memory ............................................................. 59
Program Memory ....................................................... 53
Memory Programming Requirements .............................. 337
Migration from Baseline to Enhanced Devices ................ 372
Migration from High-End to Enhanced Devices ............... 373
Migration from Mid-Range to Enhanced Devices ............ 373
MOVF ............................................................................... 291
MOVFF ............................................................................ 292
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 379
PIC18F2420/2520/4420/4520
Pin Functions
MCLR/VPP/RE3 .................................................... 12, 16
PORTC
Associated Registers ............................................... 113
OSC1/CLKI/RA7 .................................................. 12, 16
OSC2/CLKO/RA6 ................................................ 12, 16
RA0/AN0 .............................................................. 13, 17
RA1/AN1 .............................................................. 13, 17
RA2/AN2/VREF-/CVREF ........................................ 13, 17
RA3/AN3/VREF+ ................................................... 13, 17
RA4/T0CKI/C1OUT .............................................. 13, 17
RA5/AN4/SS/HLVDIN/C2OUT ............................. 13, 17
RB0/INT0/FLT0/AN12 .......................................... 14, 18
RB1/INT1/AN10 ................................................... 14, 18
RB2/INT2/AN8 ..................................................... 14, 18
RB3/AN9/CCP2 ................................................... 14, 18
RB4/KBI0/AN11 ................................................... 14, 18
RB5/KBI1/PGM .................................................... 14, 18
RB6/KBI2/PGC .................................................... 14, 18
RB7/KBI3/PGD .................................................... 14, 18
RC0/T1OSO/T13CKI ...........................................15, 19
RC1/T1OSI/CCP2 ................................................ 15, 19
RC2/CCP1 .................................................................15
RC2/CCP1/P1A .........................................................19
RC3/SCK/SCL ..................................................... 15, 19
RC4/SDI/SDA ...................................................... 15, 19
RC5/SDO ............................................................. 15, 19
RC6/TX/CK .......................................................... 15, 19
RC7/RX/DT .......................................................... 15, 19
RD0/PSP0 ..................................................................20
RD1/PSP1 ..................................................................20
RD2/PSP2 ..................................................................20
RD3/PSP3 ..................................................................20
RD4/PSP4 ..................................................................20
RD5/PSP5/P1B ..........................................................20
RD6/PSP6/P1C ..........................................................20
RD7/PSP7/P1D ..........................................................20
RE0/RD/AN5 ..............................................................21
RE1/WR/AN6 .............................................................21
RE2/CS/AN7 ..............................................................21
VDD ....................................................................... 15, 21
VSS ....................................................................... 15, 21
Pinout I/O Descriptions
LATC Register ......................................................... 111
PORTC Register ...................................................... 111
RC3/SCK/SCL Pin ................................................... 175
TRISC Register ........................................................ 111
PORTD
Associated Registers ............................................... 116
LATD Register ......................................................... 114
Parallel Slave Port (PSP) Function .......................... 114
PORTD Register ...................................................... 114
TRISD Register ........................................................ 114
PORTE
Associated Registers ............................................... 119
LATE Register ......................................................... 117
PORTE Register ...................................................... 117
PSP Mode Select (PSPMODE Bit) .......................... 114
TRISE Register ........................................................ 117
Power Managed Modes ..................................................... 33
and A/D Operation ................................................... 230
and EUSART Operation .......................................... 205
and Multiple Sleep Commands .................................. 34
and PWM Operation ................................................ 159
and SPI Operation ................................................... 169
Clock Transitions and Status Indicators .................... 34
Effects on Clock Sources ........................................... 31
Entering ..................................................................... 33
Exiting Idle and Sleep Modes .................................... 39
by Interrupt ........................................................ 39
by Reset ............................................................ 39
by WDT Time-out .............................................. 39
Without a Start-up Delay ................................... 40
Idle Modes ................................................................. 37
PRI_IDLE ........................................................... 38
RC_IDLE ........................................................... 39
SEC_IDLE ......................................................... 38
Run Modes ................................................................ 34
PRI_RUN ........................................................... 34
RC_RUN ............................................................ 35
SEC_RUN ......................................................... 34
Selecting .................................................................... 33
Sleep Mode ............................................................... 37
Summary (table) ........................................................ 33
Power-on Reset (POR) ...................................................... 43
Power-up Timer (PWRT) ........................................... 45
Time-out Sequence ................................................... 45
Power-up Delays ............................................................... 31
Power-up Timer (PWRT) ................................................... 31
Prescaler
PIC18F2420/2520 ......................................................12
PIC18F4420/4520 ......................................................16
PIR Registers .....................................................................96
PLL Frequency Multiplier ...................................................25
HSPLL Oscillator Mode ..............................................25
Use with INTOSC .......................................................25
POP ..................................................................................296
POR. See Power-on Reset.
PORTA
Timer2 ..................................................................... 150
Prescaler, Timer0 ............................................................ 125
Prescaler, Timer2 ............................................................ 145
PRI_IDLE Mode ................................................................. 38
PRI_RUN Mode ................................................................. 34
PRO MATE II Universal Device Programmer .................. 319
Program Counter ............................................................... 54
PCL, PCH and PCU Registers .................................. 54
PCLATH and PCLATU Registers .............................. 54
Associated Registers ...............................................107
LATA Register ..........................................................105
PORTA Register ......................................................105
TRISA Register ........................................................105
PORTB
Associated Registers ...............................................110
LATB Register ..........................................................108
PORTB Register ......................................................108
RB7:RB4 Interrupt-on-Change Flag
(RBIF Bit) .........................................................108
TRISB Register ........................................................108
DS39631A-page 380
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
Program Memory
and Extended Instruction Set ..................................... 72
Code Protection ....................................................... 264
Registers
ADCON0 (A/D Control 0) ......................................... 223
ADCON1 (A/D Control 1) ......................................... 224
ADCON2 (A/D Control 2) ......................................... 225
BAUDCON (Baud Rate Control) .............................. 204
CCP1CON (Enhanced
Instructions ................................................................. 58
Two-Word .......................................................... 58
Interrupt Vector .......................................................... 53
Look-up Tables .......................................................... 56
Map and Stack (diagram) ........................................... 53
Reset Vector .............................................................. 53
Program Verification and Code Protection ....................... 263
Associated Registers ............................................... 263
Programming, Device Instructions ................................... 267
PSP. See Parallel Slave Port.
Pulse-Width Modulation. See PWM (CCP Module)
and PWM (ECCP Module).
PUSH ............................................................................... 296
PUSH and POP Instructions .............................................. 55
PUSHL ............................................................................. 312
PWM (CCP Module)
Associated Registers ............................................... 146
Auto-Shutdown (CCP1 only) .................................... 145
CCPR1H:CCPR1L Registers ................................... 149
Duty Cycle ........................................................ 144, 150
Example Frequencies/Resolutions .................. 145, 150
Period ............................................................... 144, 149
Setup for PWM Operation ........................................ 145
TMR2 to PR2 Match ........................................ 144, 149
PWM (ECCP Module) ...................................................... 149
Direction Change in Full-Bridge
Capture/Compare/PWM Control 1) ................. 147
CCPxCON (Standard
Capture/Compare/PWM Control) .................... 139
CMCON (Comparator Control) ................................ 233
CONFIG1H (Configuration 1 High) .......................... 250
CONFIG2H (Configuration 2 High) .......................... 252
CONFIG2L (Configuration 2 Low) ........................... 251
CONFIG3H (Configuration 3 High) .......................... 253
CONFIG4L (Configuration 4 Low) ........................... 253
CONFIG5H (Configuration 5 High) .......................... 254
CONFIG5L (Configuration 5 Low) ........................... 254
CONFIG6H (Configuration 6 High) .......................... 255
CONFIG6L (Configuration 6 Low) ........................... 255
CONFIG7H (Configuration 7 High) .......................... 256
CONFIG7L (Configuration 7 Low) ........................... 256
CVRCON (Comparator Voltage
Reference Control) .......................................... 239
DEVID1 (Device ID 1) .............................................. 257
DEVID2 (Device ID 2) .............................................. 257
ECCP1AS (ECCP Auto-Shutdown Control) ............ 157
EECON1 (Data EEPROM Control 1) ................... 75, 84
HLVDCON (High/Low-Voltage Detect Control) ....... 243
INTCON (Interrupt Control) ....................................... 93
INTCON2 (Interrupt Control 2) .................................. 94
INTCON3 (Interrupt Control 3) .................................. 95
IPR1 (Peripheral Interrupt Priority 1) ....................... 100
IPR2 (Peripheral Interrupt Priority 2) ....................... 101
OSCCON (Oscillator Control) .................................... 30
OSCTUNE (Oscillator Tuning) ................................... 27
PIE1 (Peripheral Interrupt Enable 1) ......................... 98
PIE2 (Peripheral Interrupt Enable 2) ......................... 99
PIR1 (Peripheral Interrupt Request (Flag) 1) ............. 96
PIR2 (Peripheral Interrupt Request (Flag) 2) ............. 97
PWM1CON (PWM Configuration) ........................... 156
RCON (Reset Control) ....................................... 42, 102
RCSTA (Receive Status and Control) ..................... 203
Output Mode .................................................... 154
Effects of a Reset ..................................................... 159
Enhanced PWM Auto-Shutdown ............................. 156
Full-Bridge Application Example .............................. 154
Full-Bridge Mode ...................................................... 153
Half-Bridge Mode ..................................................... 152
Half-Bridge Output Mode
Applications Example ...................................... 152
Operation in Power Managed Modes ...................... 159
Operation with Fail-Safe Clock Monitor ................... 159
Output Configurations .............................................. 150
Output Relationships (Active-High) .......................... 151
Output Relationships (Active-Low) ........................... 151
Programmable Dead-Band Delay ............................ 156
Setup for PWM Operation ........................................ 159
Start-up Considerations ........................................... 158
2
SSPCON1 (MSSP Control 1, I C Mode) ................. 172
SSPCON1 (MSSP Control 1, SPI Mode) ................ 163
SSPCON2 (MSSP Control 2, I C Mode) ................. 173
SSPSTAT (MSSP Status, I C Mode) ...................... 171
2
2
Q
SSPSTAT (MSSP Status, SPI Mode) ...................... 162
Status ........................................................................ 67
STKPTR (Stack Pointer) ............................................ 55
T0CON (Timer0 Control) ......................................... 123
T1CON (Timer1 Control) ......................................... 127
T2CON (Timer2 Control) ......................................... 133
T3CON (Timer3 Control) ......................................... 135
TRISE (PORTE/PSP Control) ................................. 118
TXSTA (Transmit Status and Control) ..................... 202
WDTCON (Watchdog Timer Control) ...................... 259
RESET ............................................................................. 297
Reset State of Registers .................................................... 48
Resets ....................................................................... 41, 249
Brown-out Reset (BOR) ........................................... 249
Oscillator Start-up Timer (OST) ............................... 249
Power-on Reset (POR) ............................................ 249
Power-up Timer (PWRT) ......................................... 249
Q Clock .................................................................... 145, 150
R
RAM. See Data Memory.
RBIF Bit ............................................................................ 108
RC Oscillator ...................................................................... 25
RCIO Oscillator Mode ................................................ 25
RC_IDLE Mode .................................................................. 39
RC_RUN Mode .................................................................. 35
RCALL ............................................................................. 297
RCON Register
Bit Status During Initialization .................................... 48
Register File ....................................................................... 62
Register File Summary ................................................ 64–66
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 381
PIC18F2420/2520/4420/4520
RETFIE ............................................................................298
RETLW .............................................................................298
RETURN ..........................................................................299
Return Address Stack ........................................................54
Return Stack Pointer (STKPTR) ........................................55
Revision History ...............................................................371
RLCF ................................................................................299
RLNCF .............................................................................300
RRCF ...............................................................................300
RRNCF .............................................................................301
SUBULNK ........................................................................ 313
SUBWF ............................................................................ 303
SUBWFB ......................................................................... 304
SWAPF ............................................................................ 304
T
Table Pointer Operations (table) ........................................ 76
Table Reads/Table Writes ................................................. 56
TBLRD ............................................................................. 305
TBLWT ............................................................................. 306
Time-out in Various Situations (table) ................................ 45
Timer0 .............................................................................. 123
Associated Registers ............................................... 125
Operation ................................................................. 124
Overflow Interrupt .................................................... 125
Prescaler ................................................................. 125
Prescaler Assignment (PSA Bit) .............................. 125
Prescaler Select (T0PS2:T0PS0 Bits) ..................... 125
Prescaler. See Prescaler, Timer0.
Reads and Writes in 16-Bit Mode ............................ 124
Source Edge Select (T0SE Bit) ............................... 124
Source Select (T0CS Bit) ......................................... 124
Switching Prescaler Assignment ............................. 125
Timer1 .............................................................................. 127
16-Bit Read/Write Mode .......................................... 129
Associated Registers ............................................... 131
Interrupt ................................................................... 130
Operation ................................................................. 128
Oscillator .......................................................... 127, 129
Oscillator Layout Considerations ............................. 130
Overflow Interrupt .................................................... 127
Resetting, Using the CCP
Special Event Trigger ...................................... 130
Special Event Trigger (ECCP) ................................. 148
TMR1H Register ...................................................... 127
TMR1L Register ....................................................... 127
Use as a Real-Time Clock ....................................... 130
Timer2 .............................................................................. 133
Associated Registers ............................................... 134
Interrupt ................................................................... 134
Operation ................................................................. 133
Output ...................................................................... 134
PR2 Register ................................................... 144, 149
TMR2 to PR2 Match Interrupt .......................... 144, 149
Timer3 .............................................................................. 135
16-Bit Read/Write Mode .......................................... 137
Associated Registers ............................................... 137
Operation ................................................................. 136
Oscillator .......................................................... 135, 137
Overflow Interrupt ............................................ 135, 137
Special Event Trigger (CCP) ................................... 137
TMR3H Register ...................................................... 135
TMR3L Register ....................................................... 135
Timing Diagrams
S
SCK ..................................................................................161
SDI ...................................................................................161
SDO .................................................................................161
SEC_IDLE Mode ................................................................38
SEC_RUN Mode ................................................................34
Serial Clock, SCK .............................................................161
Serial Data In (SDI) ..........................................................161
Serial Data Out (SDO) .....................................................161
Serial Peripheral Interface. See SPI Mode.
SETF ................................................................................301
Single-Supply ICSP Programming.
Slave Select (SS) .............................................................161
Slave Select Synchronization ...........................................167
SLEEP ..............................................................................302
Sleep
OSC1 and OSC2 Pin States ......................................31
Sleep Mode ........................................................................37
Software Simulator (MPLAB SIM) ....................................318
Software Simulator (MPLAB SIM30) ................................318
Special Event Trigger. See Compare (ECCP Mode).
Special Event Trigger. See Compare (ECCP Module).
Special Features of the CPU ............................................249
Special Function Registers ................................................63
Map ............................................................................63
SPI Mode (MSSP)
Associated Registers ...............................................169
Bus Mode Compatibility ...........................................169
Effects of a Reset .....................................................169
Enabling SPI I/O ......................................................165
Master Mode ............................................................166
Master/Slave Connection .........................................165
Operation .................................................................164
Operation in Power Managed Modes ......................169
Serial Clock ..............................................................161
Serial Data In ...........................................................161
Serial Data Out ........................................................161
Slave Mode ..............................................................167
Slave Select .............................................................161
Slave Select Synchronization ..................................167
SPI Clock .................................................................166
Typical Connection ..................................................165
SS ....................................................................................161
SSPOV .............................................................................191
SSPOV Status Flag ..........................................................191
SSPSTAT Register
A/D Conversion ........................................................ 359
Acknowledge Sequence .......................................... 194
Asynchronous Reception ......................................... 214
Asynchronous Transmission .................................... 212
Asynchronous Transmission (Back to Back) ........... 212
Automatic Baud Rate Calculation ............................ 210
Auto-Wake-up Bit (WUE) During
R/W Bit ............................................................. 174, 175
Stack Full/Underflow Resets ..............................................56
Standard Instructions .......................................................267
SUBFSR ...........................................................................313
SUBFWB ..........................................................................302
SUBLW ............................................................................303
Normal Operation ............................................ 215
Auto-Wake-up Bit (WUE) During Sleep ................... 215
DS39631A-page 382
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
Baud Rate Generator with Clock Arbitration ............ 188
BRG Overflow Sequence ......................................... 210
BRG Reset Due to SDA Arbitration
PWM Output ............................................................ 144
Repeat Start Condition ............................................ 190
Reset, Watchdog Timer (WDT),
During Start Condition ..................................... 197
Brown-out Reset (BOR) ........................................... 345
Bus Collision During a Repeated
Start Condition (Case 1) .................................. 198
Bus Collision During a Repeated
Oscillator Start-up Timer (OST),
Power-up Timer (PWRT) ................................. 345
Send Break Character Sequence ............................ 216
Slave Synchronization ............................................. 167
Slow Rise Time (MCLR Tied to VDD,
Start Condition (Case 2) .................................. 198
Bus Collision During a Start Condition
(SCL = 0) ......................................................... 197
Bus Collision During a Stop Condition
(Case 1) ........................................................... 199
Bus Collision During a Stop Condition
(Case 2) ........................................................... 199
Bus Collision During Start Condition
(SDA only) ....................................................... 196
Bus Collision for Transmit and Acknowledge ........... 195
Capture/Compare/PWM (CCP) ................................ 347
CLKO and I/O .......................................................... 344
Clock Synchronization ............................................. 181
Clock/Instruction Cycle .............................................. 57
Example SPI Master Mode (CKE = 0) ..................... 349
Example SPI Master Mode (CKE = 1) ..................... 350
Example SPI Slave Mode (CKE = 0) ....................... 351
Example SPI Slave Mode (CKE = 1) ....................... 352
External Clock (All Modes except PLL) .................... 342
Fail-Safe Clock Monitor (FSCM) .............................. 262
First Start Bit Timing ................................................ 189
Full-Bridge PWM Output .......................................... 153
Half-Bridge PWM Output ......................................... 152
High/Low-Voltage Detect Characteristics ................ 339
High/Low-Voltage Detect Operation
VDD Rise > TPWRT) ............................................ 47
SPI Mode (Master Mode) ........................................ 166
SPI Mode (Slave Mode, CKE = 0) ........................... 168
SPI Mode (Slave Mode, CKE = 1) ........................... 168
Synchronous Reception
(Master Mode, SREN) ..................................... 219
Synchronous Transmission ..................................... 217
Synchronous Transmission (Through TXEN) .......... 218
Time-out Sequence on POR w/PLL Enabled
(MCLR Tied to VDD) .......................................... 47
Time-out Sequence on Power-up
(MCLR Not Tied to VDD, Case 1) ...................... 46
Time-out Sequence on Power-up
(MCLR Not Tied to VDD, Case 2) ...................... 46
Time-out Sequence on Power-up
(MCLR Tied to VDD, VDD Rise < TPWRT) ........... 46
Timer0 and Timer1 External Clock .......................... 346
Transition for Entry to SEC_RUN Mode .................... 35
Transition for Entry to Sleep Mode ............................ 37
Transition for Two-Speed Start-up
(INTOSC to HSPLL) ........................................ 260
Transition for Wake from Sleep (HSPLL) .................. 37
Transition from RC_RUN Mode to
PRI_RUN Mode ................................................. 36
Transition from SEC_RUN Mode to
(VDIRMAG = 0) ................................................ 245
High/Low-Voltage Detect Operation
PRI_RUN Mode (HSPLL) .................................. 35
Transition Timing for Entry to Idle Mode .................... 38
Transition Timing for Wake from
Idle to Run Mode ............................................... 38
Transition to RC_RUN Mode ..................................... 36
USART Synchronous Receive
(VDIRMAG = 1) ................................................ 246
I C Bus Data ............................................................ 353
I C Bus Start/Stop Bits ............................................. 353
I C Master Mode (7 or 10-Bit Transmission) ........... 192
I C Master Mode (7-Bit Reception) .......................... 193
I C Slave Mode (10-Bit Reception, SEN = 0) .......... 178
I C Slave Mode (10-Bit Reception, SEN = 1) .......... 183
I C Slave Mode (10-Bit Transmission) ..................... 179
2
2
2
2
(Master/Slave) ................................................. 357
USART Synchronous Transmission
2
2
(Master/Slave) ................................................. 357
Timing Diagrams and Specifications ............................... 342
A/D Conversion Requirements ................................ 359
Capture/Compare/PWM Requirements ................... 347
CLKO and I/O Requirements ................................... 344
Example SPI Mode Requirements
2
2
I C Slave Mode (7-bit Reception, SEN = 0) ............. 176
I C Slave Mode (7-Bit Reception, SEN = 1) ............ 182
I C Slave Mode (7-Bit Transmission) ....................... 177
2
2
2
I C Slave Mode General Call Address
Sequence (7 or 10-Bit Address Mode) ............ 184
I C Stop Condition Receive or
(Master Mode, CKE = 0) .................................. 349
Example SPI Mode Requirements
2
Transmit Mode ................................................. 194
(Master Mode, CKE = 1) .................................. 350
Example SPI Mode Requirements
(Slave Mode, CKE = 0) .................................... 351
Example SPI Mode Requirements
2
Master SSP I C Bus Data ........................................ 355
2
Master SSP I C Bus Start/Stop Bits ........................ 355
Parallel Slave Port (PIC18F4420/4520) ................... 348
Parallel Slave Port (PSP) Read ............................... 121
Parallel Slave Port (PSP) Write ............................... 121
PWM Auto-Shutdown (PRSEN = 0,
Auto-Restart Disabled) .................................... 158
PWM Auto-Shutdown (PRSEN = 1,
Auto-Restart Enabled) ..................................... 158
PWM Direction Change ........................................... 155
PWM Direction Change at Near
(Slave Mode, CKE = 1) .................................... 352
External Clock Requirements .................................. 342
2
I C Bus Data Requirements (Slave Mode) .............. 354
2
I C Bus Start/Stop Bits Requirements
(Slave Mode) ................................................... 353
2
Master SSP I C Bus Data Requirements ................ 356
2
Master SSP I C Bus Start/Stop Bits
Requirements .................................................. 355
Parallel Slave Port Requirements
100% Duty Cycle ............................................. 155
(PIC18F4420/4520) ......................................... 348
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 383
PIC18F2420/2520/4420/4520
PLL Clock .................................................................343
Reset, Watchdog Timer, Oscillator Start-up Timer,
V
Voltage Reference Specifications .................................... 338
Power-up Timer and Brown-out Reset
Requirements ...................................................345
Timer0 and Timer1 External
Clock Requirements .........................................346
USART Synchronous Receive Requirements .........357
USART Synchronous Transmission
W
Watchdog Timer (WDT) ........................................... 249, 258
Associated Registers ............................................... 259
Control Register ....................................................... 258
During Oscillator Failure .......................................... 261
Programming Considerations .................................. 258
WCOL ...................................................... 189, 190, 191, 194
WCOL Status Flag ................................... 189, 190, 191, 194
WWW, On-Line Support ...................................................... 6
Requirements ...................................................357
Top-of-Stack Access ..........................................................54
TRISE Register
PSPMODE Bit ..........................................................114
TSTFSZ ............................................................................307
Two-Speed Start-up ................................................. 249, 260
Two-Word Instructions
X
XORLW ............................................................................ 307
XORWF ........................................................................... 308
Example Cases ..........................................................58
TXSTA Register
BRGH Bit .................................................................205
DS39631A-page 384
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
ON-LINE SUPPORT
SYSTEMS INFORMATION AND
UPGRADE HOT LINE
Microchip provides on-line support on the Microchip
World Wide Web site.
The Systems Information and Upgrade Line provides
system users a listing of the latest versions of all of
Microchip’s development systems software products.
Plus, this line provides information on how customers
can receive the most current upgrade kits.The Hot Line
Numbers are:
The web site is used by Microchip as a means to make
files and information easily available to customers. To
view the site, the user must have access to the Internet
and a web browser, such as Netscape® or Microsoft®
Internet Explorer. Files are also available for FTP
download from our FTP site.
1-800-755-2345 for U.S. and most of Canada and
1-480-792-7302 for the rest of the world.
Connecting to the Microchip Internet
Web Site
042003
The Microchip web site is available at the following
URL:
www.microchip.com
The file transfer site is available by using an FTP
service to connect to:
ftp://ftp.microchip.com
The web site and file transfer site provide a variety of
services. Users may download files for the latest
Development Tools, Data Sheets, Application Notes,
User’s Guides, Articles and Sample Programs. A vari-
ety of Microchip specific business information is also
available, including listings of Microchip sales offices,
distributors and factory representatives. Other data
available for consideration is:
• Latest Microchip Press Releases
• Technical Support Section with Frequently Asked
Questions
• Design Tips
• Device Errata
• Job Postings
• Microchip Consultant Program Member Listing
• Links to other useful web sites related to
Microchip Products
• Conferences for products, Development Systems,
technical information and more
• Listing of seminars and events
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 385
PIC18F2420/2520/4420/4520
READER RESPONSE
It is our intention to provide you with the best documentation possible to ensure successful use of your Microchip prod-
uct. If you wish to provide your comments on organization, clarity, subject matter and ways in which our documentation
can better serve you, please FAX your comments to the Technical Publications Manager at (480) 792-4150.
Please list the following information and use this outline to provide us with your comments about this document.
To:
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Reader Response
Total Pages Sent ________
RE:
From:
Name
Company
Address
City / State / ZIP / Country
Telephone: (_______) _________ - _________
FAX: (______) _________ - _________
Application (optional):
Would you like a reply?
Y
N
PIC18F2420/2520/4420/4520
DS39631A
Literature Number:
Device:
Questions:
1. What are the best features of this document?
2. How does this document meet your hardware and software development needs?
3. Do you find the organization of this document easy to follow? If not, why?
4. What additions to the document do you think would enhance the structure and subject?
5. What deletions from the document could be made without affecting the overall usefulness?
6. Is there any incorrect or misleading information (what and where)?
7. How would you improve this document?
DS39631A-page 386
Preliminary
2004 Microchip Technology Inc.
PIC18F2420/2520/4420/4520
PIC18F2420/2520/4420/4520 PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
PART NO.
Device
X
/XX
XXX
Examples:
Temperature
Range
Package
Pattern
a)
PIC18LF4520-I/P 301 = Industrial temp., PDIP
package, Extended VDD limits, QTP pattern
#301.
b)
c)
PIC18LF2420-I/SO = Industrial temp., SOIC
package, Extended VDD limits.
Device
PIC18F2420/2520(1), PIC18F4420/4520(1)
,
PIC18F4420-I/P = Industrial temp., PDIP
package, normal VDD limits.
PIC18F2420/2520T(2), PIC18F4420/4520T(2)
VDD range 4.2V to 5.5V
;
PIC18LF2420/2520(1), PIC18LF4420/4520(1)
,
PIC18LF2420/2520T(2), PIC18LF4420/4520T(2)
VDD range 2.0V to 5.5V
;
Temperature Range
Package
I
E
=
=
-40°C to +85°C (Industrial)
-40°C to +125°C (Extended)
PT
SO
SP
P
=
=
=
=
=
TQFP (Thin Quad Flatpack)
Note 1:
2:
F
LF
T
=
=
=
Standard Voltage Range
Wide Voltage Range
in tape and reel TQFP
packages only.
SOIC
Skinny Plastic DIP
PDIP
QFN
ML
Pattern
QTP, SQTP, Code or Special Requirements
(blank otherwise)
2004 Microchip Technology Inc.
Preliminary
DS39631A-page 387
WORLDWIDE SALES AND SERVICE
China - Beijing
Korea
AMERICAS
Corporate Office
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200
Fax: 480-792-7277
Technical Support: 480-792-7627
Web Address: www.microchip.com
Unit 706B
168-1, Youngbo Bldg. 3 Floor
Samsung-Dong, Kangnam-Ku
Seoul, Korea 135-882
Wan Tai Bei Hai Bldg.
No. 6 Chaoyangmen Bei Str.
Beijing, 100027, China
Tel: 86-10-85282100
Fax: 86-10-85282104
Tel: 82-2-554-7200 Fax: 82-2-558-5932 or
82-2-558-5934
Singapore
200 Middle Road
#07-02 Prime Centre
Singapore, 188980
Tel: 65-6334-8870 Fax: 65-6334-8850
China - Chengdu
Rm. 2401-2402, 24th Floor,
Ming Xing Financial Tower
No. 88 TIDU Street
Chengdu 610016, China
Tel: 86-28-86766200
Atlanta
3780 Mansell Road, Suite 130
Alpharetta, GA 30022
Tel: 770-640-0034
Fax: 770-640-0307
Taiwan
Kaohsiung Branch
30F - 1 No. 8
Fax: 86-28-86766599
Boston
Min Chuan 2nd Road
Kaohsiung 806, Taiwan
Tel: 886-7-536-4818
Fax: 886-7-536-4803
China - Fuzhou
Unit 28F, World Trade Plaza
No. 71 Wusi Road
Fuzhou 350001, China
Tel: 86-591-7503506
Fax: 86-591-7503521
2 Lan Drive, Suite 120
Westford, MA 01886
Tel: 978-692-3848
Fax: 978-692-3821
Taiwan
Taiwan Branch
11F-3, No. 207
Tung Hua North Road
Taipei, 105, Taiwan
Tel: 886-2-2717-7175 Fax: 886-2-2545-0139
Chicago
333 Pierce Road, Suite 180
Itasca, IL 60143
Tel: 630-285-0071
Fax: 630-285-0075
China - Hong Kong SAR
Unit 901-6, Tower 2, Metroplaza
223 Hing Fong Road
Kwai Fong, N.T., Hong Kong
Tel: 852-2401-1200
Fax: 852-2401-3431
Dallas
EUROPE
Austria
Durisolstrasse 2
A-4600 Wels
Austria
Tel: 43-7242-2244-399
Fax: 43-7242-2244-393
Denmark
Regus Business Centre
Lautrup hoj 1-3
4570 Westgrove Drive, Suite 160
Addison, TX 75001
Tel: 972-818-7423
Fax: 972-818-2924
China - Shanghai
Room 701, Bldg. B
Far East International Plaza
No. 317 Xian Xia Road
Shanghai, 200051
Detroit
Tri-Atria Office Building
32255 Northwestern Highway, Suite 190
Farmington Hills, MI 48334
Tel: 248-538-2250
Tel: 86-21-6275-5700
Fax: 86-21-6275-5060
China - Shenzhen
Rm. 1812, 18/F, Building A, United Plaza
No. 5022 Binhe Road, Futian District
Shenzhen 518033, China
Tel: 86-755-82901380
Fax: 86-755-8295-1393
China - Shunde
Fax: 248-538-2260
Ballerup DK-2750 Denmark
Tel: 45-4420-9895 Fax: 45-4420-9910
Kokomo
France
2767 S. Albright Road
Kokomo, IN 46902
Tel: 765-864-8360
Fax: 765-864-8387
Parc d’Activite du Moulin de Massy
43 Rue du Saule Trapu
Batiment A - ler Etage
91300 Massy, France
Tel: 33-1-69-53-63-20
Fax: 33-1-69-30-90-79
Room 401, Hongjian Building, No. 2
Los Angeles
18201 Von Karman, Suite 1090
Irvine, CA 92612
Tel: 949-263-1888
Fax: 949-263-1338
Fengxiangnan Road, Ronggui Town, Shunde
District, Foshan City, Guangdong 528303, China
Tel: 86-757-28395507 Fax: 86-757-28395571
Germany
China - Qingdao
Rm. B505A, Fullhope Plaza,
No. 12 Hong Kong Central Rd.
Qingdao 266071, China
Tel: 86-532-5027355 Fax: 86-532-5027205
Steinheilstrasse 10
D-85737 Ismaning, Germany
Tel: 49-89-627-144-0
Fax: 49-89-627-144-44
San Jose
1300 Terra Bella Avenue
Mountain View, CA 94043
Tel: 650-215-1444
Italy
India
Via Quasimodo, 12
20025 Legnano (MI)
Milan, Italy
Divyasree Chambers
1 Floor, Wing A (A3/A4)
No. 11, O’Shaugnessey Road
Bangalore, 560 025, India
Tel: 91-80-22290061 Fax: 91-80-22290062
Japan
Fax: 650-961-0286
Toronto
Tel: 39-0331-742611
Fax: 39-0331-466781
Netherlands
Waegenburghtplein 4
NL-5152 JR, Drunen, Netherlands
Tel: 31-416-690399
6285 Northam Drive, Suite 108
Mississauga, Ontario L4V 1X5, Canada
Tel: 905-673-0699
Fax: 905-673-6509
Benex S-1 6F
3-18-20, Shinyokohama
Kohoku-Ku, Yokohama-shi
Kanagawa, 222-0033, Japan
Tel: 81-45-471- 6166 Fax: 81-45-471-6122
ASIA/PACIFIC
Australia
Suite 22, 41 Rawson Street
Epping 2121, NSW
Australia
Tel: 61-2-9868-6733
Fax: 61-2-9868-6755
Fax: 31-416-690340
United Kingdom
505 Eskdale Road
Winnersh Triangle
Wokingham
Berkshire, England RG41 5TU
Tel: 44-118-921-5869
Fax: 44-118-921-5820
05/28/04
DS39631A-page 388
Preliminary
2004 Microchip Technology Inc.
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