PIC18F4331-I/PXXX [MICROCHIP]
PIC18F4331-I/PXXX;
| 型号： | PIC18F4331-I/PXXX |
| 厂家： | 
MICROCHIP |
| 描述： | PIC18F4331-I/PXXX 闪存 微控制器 |
| 文件： | 总400页 (文件大小：6744K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PIC18F2331/2431/4331/4431
Data Sheet
28/40/44-Pin Enhanced Flash
Microcontrollers with nanoWatt Technology,
High-Performance PWM and A/D
© 2007 Microchip Technology Inc.
Preliminary
DS39616C
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 provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR
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Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, KEELOQ logo, microID, MPLAB, PIC,
PICmicro, PICSTART, PRO MATE, rfPIC and SmartShunt are
registered trademarks of Microchip Technology Incorporated
in the U.S.A. and other countries.
AmpLab, FilterLab, Linear Active Thermistor, Migratable
Memory, MXDEV, MXLAB, 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, CodeGuard,
dsPICDEM, dsPICDEM.net, dsPICworks, ECAN,
ECONOMONITOR, FanSense, FlexROM, fuzzyLAB,
In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi,
MPASM, MPLAB Certified logo, MPLIB, MPLINK, PICkit,
PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal,
PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, Select
Mode, Smart Serial, SmartTel, Total Endurance, UNI/O,
WiperLock and ZENA 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.
© 2007, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received ISO/TS-16949:2002 certification for its worldwide
headquarters, design and wafer fabrication facilities in Chandler and
Tempe, Arizona; Gresham, Oregon and design centers in California
and India. The Company’s quality system processes and procedures
are for its PIC® MCUs and dsPIC® DSCs, 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.
DS39616C-page ii
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
28/40/44-Pin Enhanced Flash Microcontrollers with
nanoWatt Technology, High-Performance PWM and A/D
14-Bit Power Control PWM Module:
Power-Managed Modes:
• Up to 4 Channels with Complementary Outputs
• Edge or Center-Aligned Operation
• Run: CPU on, Peripherals on
• Idle: CPU off, Peripherals on
• Flexible Dead-Band Generator
• Sleep: CPU off, Peripherals off
• Hardware Fault Protection Inputs
• Simultaneous Update of Duty Cycle and Period:
- Flexible Special Event Trigger output
• Idle mode Currents Down to 5.8 μA, Typical
• Sleep Current Down to 0.1 μA, Typical
• Timer1 Oscillator, 1.8 μA, Typical, 32 kHz, 2V
• Watchdog Timer (WDT), 2.1 μA, typical
• Oscillator Two-Speed Start-up
Motion Feedback Module:
• Three Independent Input Capture Channels:
Peripheral Highlights:
• High-Current Sink/Source 25 mA/25 mA
• Three External Interrupts
• Two Capture/Compare/PWM (CCP) modules:
- Capture is 16-bit, max. resolution 6.25 ns (TCY/16)
- Compare is 16-bit, max. resolution 100 ns (TCY)
- PWM output: PWM resolution is 1 to 10 bits
• Enhanced USART module:
- Supports RS-485, RS-232 and LIN 1.2
- Auto-wake-up on Start bit
- Auto-Baud Detect
• RS-232 Operation using Internal Oscillator Block
(no external crystal required)
- Flexible operating modes for period and
pulse-width measurement
- Special Hall sensor interface module
- Special Event Trigger output to other modules
• Quadrature Encoder Interface:
- 2-phase inputs and one index input from encoder
- High and low position tracking with direction
status and change of direction interrupt
- Velocity measurement
High-Speed, 200 ksps 10-Bit A/D Converter:
• Up to 9 Channels
• Simultaneous, Two-Channel Sampling
• Sequential Sampling: 1, 2 or 4 Selected Channels
• Auto-Conversion Capability
Special Microcontroller Features:
• 4-Word FIFO with Selectable Interrupt Frequency
• Selectable External Conversion Triggers
• Programmable Acquisition Time
• 100,000 Erase/Write Cycle Enhanced Flash
Program Memory, Typical
• 1,000,000 Erase/Write Cycle Data EEPROM
Memory, Typical
Flexible Oscillator Structure:
• Four Crystal modes up to 40 MHz
• Flash/Data EEPROM Retention: 100 Years
• Self-Programmable under Software Control
• Priority Levels for Interrupts
• 8 x 8 Single-Cycle Hardware Multiplier
• Extended Watchdog Timer (WDT):
- Programmable period from 41 ms to 131s
• Two External Clock modes up to 40 MHz
• Internal Oscillator Block:
- 8 user-selectable frequencies: 31 kHz to 8 MHz
- OSCTUNE can compensate for frequency drift
• Secondary Oscillator using Timer1 @ 32 kHz
• Fail-Safe Clock Monitor:
• Single-Supply In-Circuit Serial Programming™
(ICSP™) via Two Pins
• In-Circuit Debug (ICD) via Two Pins:
- Allows for safe shutdown of device if clock fails
- Drives PWM outputs safely when debugging
Program Memory
Data Memory
SSP
14-Bit
PWM
(ch)
10-Bit
A/D (ch)
Timers
8/16-Bit
Device
I/O
CCP
EUSART
Flash #Single-Word SRAM EEPROM
(bytes) Instructions (bytes) (bytes)
Slave
SPI
2
I C™
PIC18F2331 8192
PIC18F2431 16384
PIC18F4331 8192
PIC18F4431 16384
4096
8192
4096
8192
768
768
768
768
256
256
256
256
24
24
36
36
5
5
9
9
2
2
2
2
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
6
6
8
8
1/3
1/3
1/3
1/3
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 1
PIC18F2331/2431/4331/4431
Pin Diagrams
28-Pin SPDIP, SOIC
1
2
3
4
5
28
27
26
25
24
RB7/KBI3/PGD
RB6/KBI2/PGC
RB5/KBI1/PWM4/PGM
RB4/KBI0/PWM5
RB3/PWM3
MCLR/VPP/RE3
RA0/AN0
(1)
RA1/AN1
RA2/AN2/VREF-/CAP1/INDX
RA3/AN3/VREF+/CAP2/QEA
RA4/AN4/CAP3/QEB
AVDD
RB2/PWM2
6
7
8
23
22
21
RB1/PWM1
RB0/PWM0
AVSS
VDD
OSC1/CLKI/RA7
OSC2/CLKO/RA6
RC0/T1OSO/T1CKI
RC1/T1OSI/CCP2/FLTA
RC2/CCP1/FLTB
RC3/T0CKI/T5CKI/INT0
9
20
19
18
17
16
15
VSS
10
11
12
13
14
RC7/RX/DT/SDO
RC6/TX/CK/SS
RC5/INT2/SCK/SCL
RC4/INT1/SDI/SDA
Note 1: Low-Voltage Programming must be enabled.
28-Pin QFN
RA2/AN2/VREF-/CAP1/INDX
RA3/AN3/VREF+/CAP2/QEA
RA4/AN4/CAP3/QEB
VDD
1
2
3
4
5
6
7
21
20
19
18
17 VDD
16 VSS
RB3/PWM3
RB2/PWM2
RB1/PWM1
RB0/PWM0
PIC18F2331
PIC18F2431
VSS
OSC1/CLKI/RA7
OSC2/CLKO/RA6
RC7/RX/DT/SDO
15
Note 1: Low-Voltage Programming must be enabled.
DS39616C-page 2
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Pin Diagrams (Continued)
40-Pin PDIP
MCLR/VPP/RE3
RA0/AN0
1
2
3
4
5
6
7
8
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
RB7/KBI3/PGD
RB6/KBI2/PGC
RB5/KBI1/PWM4/PGM
RB4/KBI0/PWM5
RB3/PWM3
(2)
RA1/AN1
RA2/AN2/VREF-/CAP1/INDX
RA3/AN3/VREF+/CAP2/QEA
RA4/AN4/CAP3/QEB
RB2/PWM2
RA5/AN5/LVDIN
RE0/AN6
RB1/PWM1
RB0/PWM0
VDD
RE1/AN7
RE2/AN8
9
10
11
12
13
14
15
16
17
18
19
20
VSS
AVDD
AVSS
RD7/PWM7
RD6/PWM6
(4)
OSC1/CLKI/RA7
OSC2/CLKO/RA6
RC0/T1OSO/T1CKI
RC1/T1OSI/CCP2/FLTA
RC2/CCP1/FLTB
RD5/PWM4
(3)
RD4/FLTA
RC7/RX/DT/SDO
RC6/TX/CK/SS
(1)
(1)
RC5/INT2/SCK /SCL
(1)
(1)
(1)
(1)
RC3/T0CKI /T5CKI /INT0
RD0/T0CKI/T5CKI
RD1/SDO
RC4/INT1/SDI /SDA
RD3/SCK/SCL
RD2/SDI/SDA
Note 1: RC3 is the alternate pin for T0CKI/T5CKI; RC4 is the alternate pin for SDI/SDA; RC5 is the alternate pin
for SCK/SCL.
2: Low-Voltage Programming must be enabled.
3: RD4 is the alternate pin for FLTA.
4: RD5 is the alternate pin for PWM4.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 3
PIC18F2331/2431/4331/4431
Pin Diagrams (Continued)
44-Pin TQFP
NC
33
32
31
30
29
28
27
26
25
24
23
1
2
3
4
5
6
7
8
9
RC7/RX/DT/SDO
RD4/FLTA(3)
RD5/PWM4(4)
RD6/PWM6
RD7/PWM7
VSS
RC0/T1OSO/T1CKI
OSC2/CLKO/RA6
OSC1/CLKI/RA7
AVSS
AVDD
RE2/AN8
RE1/AN7
RE0/AN6
RA5/AN5/LVDIN
RA4/AN4/CAP3/QEB
PIC18F4331
PIC18F4431
VDD
RB0/PWM0
RB1/PWM1
RB2/PWM2
RB3/PWM3
10
11
Note 1: RC3 is the alternate pin for T0CKI/T5CKI; RC4 is the alternate pin for SDI/SDA; RC5 is the alternate pin
for SCK/SCL.
2: Low-Voltage Programming must be enabled.
3: RD4 is the alternate pin for FLTA.
4: RD5 is the alternate pin for PWM4.
DS39616C-page 4
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Pin Diagrams (Continued)
44-Pin QFN
OSC2/CLKO/RA6
OSC1/CLKI/RA7
VSS
1
2
3
4
5
6
7
8
9
33
32
31
30
29
28
27
26
RC7/RX/DT/SDO
RD4/FLTA(3)
RD5/PWM4(4)
RD6/PWM6
RD7/PWM7
VSS
AVSS
AVDD
VDD
RE2/AN8
RE1/AN7
RE0/AN6
RA5/AN5/LVDIN
RA4/AN4/CAP3/QEB
PIC18F4331
PIC18F4431
VDD
AVDD
RB0/PWM0
RB1/PWM1
RB2/PWM2
25
24
23
10
11
Note 1: RC3 is the alternate pin for T0CKI/T5CKI; RC4 is the alternate pin for SDI/SDA; RC5 is the alternate pin
for SCK/SCL.
2: Low-Voltage Programming must be enabled.
3: RD4 is the alternate pin for FLTA.
4: RD5 is the alternate pin for PWM4.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 5
PIC18F2331/2431/4331/4431
Table of Contents
1.0 Device Overview .......................................................................................................................................................................... 9
2.0 Oscillator Configurations ............................................................................................................................................................ 23
3.0 Power-Managed Modes ............................................................................................................................................................. 33
4.0 Reset.......................................................................................................................................................................................... 47
5.0 Memory Organization................................................................................................................................................................. 59
6.0 Flash Program Memory.............................................................................................................................................................. 77
7.0 Data EEPROM Memory ............................................................................................................................................................. 87
8.0 8 x 8 Hardware Multiplier............................................................................................................................................................ 91
9.0 Interrupts .................................................................................................................................................................................... 93
10.0 I/O Ports ................................................................................................................................................................................... 109
11.0 Timer0 Module ......................................................................................................................................................................... 135
12.0 Timer1 Module ......................................................................................................................................................................... 139
13.0 Timer2 Module ......................................................................................................................................................................... 145
14.0 Timer5 Module ......................................................................................................................................................................... 147
15.0 Capture/Compare/PWM (CCP) Modules ................................................................................................................................. 153
16.0 Motion Feedback Module......................................................................................................................................................... 159
17.0 Power Control PWM Module .................................................................................................................................................... 181
18.0 Synchronous Serial Port (SSP) Module ................................................................................................................................... 213
19.0 Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART)............................................................... 223
20.0 10-Bit High-Speed Analog-to-Digital Converter (A/D) Module ................................................................................................. 245
21.0 Low-Voltage Detect.................................................................................................................................................................. 263
22.0 Special Features of the CPU.................................................................................................................................................... 269
23.0 Instruction Set Summary.......................................................................................................................................................... 289
24.0 Development Support............................................................................................................................................................... 331
25.0 Electrical Characteristics .......................................................................................................................................................... 335
26.0 DC and AC Characteristics Graphs and Tables....................................................................................................................... 371
27.0 Packaging Information.............................................................................................................................................................. 373
Appendix A: Revision History............................................................................................................................................................. 381
Appendix B: Device Differences......................................................................................................................................................... 381
Appendix C: Conversion Considerations ........................................................................................................................................... 382
Appendix D: Migration from Baseline to Enhanced Devices.............................................................................................................. 382
Appendix E: Migration From Mid-Range to Enhanced Devices......................................................................................................... 383
Appendix F: Migration From High-End to Enhanced Devices............................................................................................................ 383
Index .................................................................................................................................................................................................. 385
The Microchip Web Site..................................................................................................................................................................... 395
Customer Change Notification Service .............................................................................................................................................. 395
Customer Support.............................................................................................................................................................................. 395
Reader Response .............................................................................................................................................................................. 396
Product Identification System............................................................................................................................................................. 397
DS39616C-page 6
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
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
products. To this end, we will continue to improve our publications to better suit your needs. Our publications will be refined and
enhanced as new volumes and updates are introduced.
If you have any questions or comments regarding this publication, please contact the Marketing Communications Department via
E-mail at docerrors@microchip.com or fax the Reader Response Form in the back of this data sheet to (480) 792-4150. We
welcome your feedback.
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To obtain the most up-to-date version of this data sheet, please register at our Worldwide Web site at:
http://www.microchip.com
You can determine the version of a data sheet by examining its literature number found on the bottom outside corner of any page.
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
devices. As device/documentation issues become known to us, we will publish an errata sheet. The errata will specify the revision
of silicon and revision of document to which it applies.
To determine if an errata sheet exists for a particular device, please check with one of the following:
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•
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When contacting a sales office, please specify which device, revision of silicon and data sheet (include literature number) you are
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© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 7
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 8
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
• 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.
1.0
DEVICE OVERVIEW
This document contains device specific information for
the following devices:
• PIC18F2331
• PIC18F2431
• PIC18F4331
• PIC18F4431
• Lower Consumption in Key Modules: The
power requirements for both Timer1 and the
Watchdog Timer have been reduced by up to
80%, with typical values of 1.1 and 2.1 μA,
respectively.
This family offers the advantages of all PIC18
microcontrollers – namely, high computational perfor-
mance at an economical price, with the addition of high
endurance enhanced Flash program memory and a
high-speed 10-bit A/D Converter. On top of these
features, the PIC18F2331/2431/4331/4431 family
introduces design enhancements that make these micro-
controllers a logical choice for many high-performance,
power control and motor control applications. These
special peripherals include:
1.1.2
MULTIPLE OSCILLATOR OPTIONS
AND FEATURES
All of the devices in the PIC18F2331/2431/4331/4431
family offer nine different oscillator options, allowing
users a wide range of choices in developing application
hardware. These include:
• 14-Bit Resolution Power Control PWM module
(PCPWM) with Programmable Dead-time Insertion
• Four Crystal modes, using crystals or ceramic
resonators.
• Motion Feedback Module (MFM), including a
3-Channel Input Capture (IC) module and
Quadrature Encoder Interface (QEI)
• 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).
• High-Speed 10-Bit A/D Converter (HSADC)
The PCPWM can generate up to eight complementary
PWM outputs with dead-band time insertion. Overdrive
current is detected by off-chip analog comparators or
the digital Fault inputs (FLTA, FLTB).
• 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, stable over temperature and VDD),
as well as a range of 6 user-selectable clock
frequencies (from 125 kHz to 4 MHz) for a total of
8 clock frequencies.
The MFM Quadrature Encoder Interface provides
precise rotor position feedback and/or velocity
measurement. The MFM 3x input capture or external
interrupts can be used to detect the rotor state for
electrically commutated motor applications using Hall
sensor feedback, such as BLDC motor drives.
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:
PIC18F2331/2431/4331/4431 devices also feature
Flash program memory and an internal RC oscillator
with built-in LP modes.
• Fail-Safe Clock Monitor: This option constantly
monitors the main clock source against a
reference 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.
1.1
New Core Features
1.1.1
nanoWatt Technology
All of the devices in the PIC18F2331/2431/4331/4431
family incorporate a range of features that can signifi-
cantly reduce power consumption during operation.
Key items include:
• 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.
This allows for code execution during what would
otherwise be the clock start-up interval, and can
even allow an application to perform routine
background activities and return to Sleep without
returning to full power operation.
• 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%.
• Multiple Idle Modes: The controller can also run
with its CPU core disabled, but the peripherals are
still active. In these states, power consumption
can be reduced even further, to as little as 4% of
normal operation requirements.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 9
PIC18F2331/2431/4331/4431
• High-Speed 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, reducing code
overhead.
1.2
Other Special Features
• 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 100 years.
• Motion Feedback Module (MFM): This module
features a Quadrature Encoder Interface (QEI)
and an Input Capture (IC) module. The QEI
accepts two phase inputs (QEA, QEB) and one
index input (INDX) from an incremental encoder.
The QEI supports high and low precision position
tracking, direction status and change of direction
interrupt and velocity measurement. The input
capture features 3 channels of independent input
capture with Timer5 as the time base, a Special
Event Trigger to other modules and an adjustable
noise filter on each IC input.
• 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.
• Power Control PWM 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 on Fault
detection and auto-restart to reactivate outputs
once the condition has cleared.
• Extended Watchdog Timer (WDT): This
enhanced version incorporates a 16-bit prescaler,
allowing a time-out range from 4 ms to over
2 minutes, that is stable across operating voltage
and temperature.
• Enhanced USART: This serial communication
module is capable of standard RS-232 operation
using the internal oscillator block, removing the
need for an external crystal (and its
accompanying power requirement) in applications
that talk to the outside world. This module also
includes Auto-Baud Detect and LIN capability.
DS39616C-page 10
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
The devices are differentiated from each other in three
ways:
1.3
Details on Individual Family
Members
1. Flash program memory (8 Kbytes for
Devices in the PIC18F2331/2431/4331/4431 family are
available in 28-pin (PIC18F2331/2431) and 40/44-pin
(PIC18F4331/4431) packages. The block diagram for
the two groups is shown in Figure 1-1.
PIC18F2331/4331 devices, 16 Kbytes for
PIC18F2431/4431).
2. A/D channels (5 for PIC18F2331/2431 devices,
9 for PIC18F4331/4431 devices).
3. I/O ports (3 bidirectional ports on PIC18F2331/
2431 devices,
5
bidirectional ports on
PIC18F4331/4431 devices).
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.
TABLE 1-1:
DEVICE FEATURES
Features
PIC18F2331
PIC18F2431
PIC18F4331
PIC18F4431
Operating Frequency
Program Memory (Bytes)
Program Memory (Instructions)
Data Memory (Bytes)
Data EEPROM Memory (Bytes)
Interrupt Sources
DC – 40 MHz
DC – 40 MHz
DC – 40 MHz
DC – 40 MHz
16384
8192
8192
16384
8192
4096
768
256
34
4096
8192
768
768
768
256
256
256
22
22
34
I/O Ports
Ports A, B, C
Ports A, B, C
Ports A, B, C, D, E Ports A, B, C, D, E
Timers
4
4
4
4
Capture/Compare/PWM modules
14-Bit Power Control PWM
2
2
2
2
(6 Channels)
(6 Channels)
(8 Channels)
(8 Channels)
Motion Feedback Module
(Input Capture/Quadrature
Encoder Interface)
1 QEI
or
3x IC
1 QEI
or
3x IC
1 QEI
or
3x IC
1 QEI
or
3x IC
Serial Communications
SSP,
SSP,
SSP,
SSP,
Enhanced USART Enhanced USART Enhanced USART Enhanced USART
10-Bit High-Speed
5 Input Channels 5 Input Channels 9 Input Channels 9 Input Channels
Analog-to-Digital Converter module
Resets (and Delays)
POR, BOR,
POR, BOR,
POR, BOR,
POR, BOR,
RESETInstruction, RESETInstruction, RESETInstruction, RESETInstruction,
Stack Full,
Stack Underflow
(PWRT, OST),
Stack Full,
Stack Underflow
(PWRT, OST),
Stack Full,
Stack Underflow
(PWRT, OST),
Stack Full,
Stack Underflow
(PWRT, OST),
MCLR (optional), MCLR (optional), MCLR (optional), MCLR (optional),
WDT
WDT
WDT
WDT
Programmable Low-Voltage Detect
Programmable Brown-out Reset
Instruction Set
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
75 Instructions
75 Instructions
75 Instructions
75 Instructions
Packages
28-pin SPDIP
28-pin SOIC
28-pin QFN
28-pin SPDIP
28-pin SOIC
28-pin QFN
40-pin PDIP
44-pin TQFP
44-pin QFN
40-pin PDIP
44-pin TQFP
44-pin QFN
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 11
PIC18F2331/2431/4331/4431
FIGURE 1-1:
PIC18F2331/2431 BLOCK DIAGRAM
Data Bus<8>
PORTA
PORTB
PORTC
RA0/AN0
RA1/AN1
RA2/AN2/VREF-/CAP1/INDX
RA3/AN3/VREF+/CAP2/QEA
RA4/AN4/CAP3/QEB
OSC2/CLKO/RA6
Table Pointer<21>
inc/dec logic
Data Latch
21
8
8
Data RAM
(768 bytes)
21
21
Address Latch
12
OSC1/CLKI/RA7
20
PCLATU PCLATH
Address Latch
Program
Memory
Address<12>
PCU PCH PCL
Program Counter
4
BSR
12
FSR0
4
RB0/PWM0
RB1/PWM1
RB2/PWM2
RB3/PWM3
RB4/KBI0/PWM5
RB5/KBI1/PWM4/PGM
RB6/KBI2/PGC
RB7/KBI3/PGD
Data Latch
Bank 0, F
FSR1
FSR2
31 Level Stack
12
16
inc/dec
logic
Decode
Table Latch
8
ROM Latch
IR
RC0/T1OSO/T1CKI
RC1/T1OSI/CCP2/FLTA
RC2/CCP1/FLTB
RC3/T0CKI/T5CKI/INT0
RC4/INT1/SDI/SDA
RC5/INT2/SCK/SCL
RC6/TX/CK/SS
8
Instruction
Decode &
Control
RC7/RX/DT/SDO
PRODH PRODL
8 x 8 Multiply
3
Power-up
Timer
OSC2/CLKO
OSC1/CLKI
T1OSI
8
Timing
W
8
BITOP
8
Oscillator
Start-up Timer
Generation
8
Power-on
Reset
8
T1OSO
4X PLL
ALU<8>
Watchdog
Timer
8
Precision
Band Gap
Reference
Brown-out
Reset
PORTE
Power-Managed
Mode Logic
MCLR/VPP
INTRC
OSC
MCLR/VPP/RE3(1,2)
VDD, VSS
Timer0
HS 10-Bit
ADC
Timer1
Timer2
AVDD, AVSS
Timer5
Synchronous
Serial Port
CCP1
CCP2
EUSART
Data EE
PCPWM
MFM
Note 1: RE3 input pin is only enabled when MCLRE fuse is programmed to ‘0’.
2: RE3 is available only when MCLR is disabled.
DS39616C-page 12
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 1-2:
PIC18F4331/4431 BLOCK DIAGRAM
Data Bus<8>
PORTA
RA0/AN0
RA1/AN1
RA2/AN2/VREF-/CAP1/INDX
RA3/AN3/VREF+/CAP2/QEA
RA4/AN4/CAP3/QEB
RA5/AN5/LVDIN
Table Pointer<21>
inc/dec logic
Data Latch
21
8
8
Data RAM
(768 bytes)
21
21
Address Latch
12
OSC2/CLKO/RA6
OSC1/CLKI/RA7
20
PCLATU PCLATH
Address Latch
Program Memory
Address<12>
PCU PCH PCL
Program Counter
PORTB
4
12
4
RB0/PWM0
Data Latch
BSR
Bank 0, F
FSR0
FSR1
FSR2
RB1/PWM1
RB2/PWM2
RB3/PWM3
31 Level Stack
12
RB4/KBI0/PWM5
RB5/KBI1/PWM4/PGM
RB6/KBI2/PGC
RB7/KBI3/PGD
16
inc/dec
logic
Decode
Table Latch
8
ROM Latch
IR
PORTC
RC0/T1OSO/T1CKI
RC1/T1OSI/CCP2/FLTA
RC2/CCP1/FLTB
RC3/T0CKI/T5CKI/INT0(3)
RC4/INT1/SDI/SDA(3)
8
RC5/INT2/SCK/SCL(3)
RC6/TX/CK/SS
Instruction
Decode &
Control
RC7/RX/DT/SDO
PRODH PRODL
8 x 8 Multiply
3
Power-up
Timer
OSC2/CLKO
OSC1/CLKI
T1OSI
8
PORTD
RD0/IT0CKI/T5CKI
RD1/SDO
RD2/SDI/SDA
Timing
Generation
W
8
BITOP
8
Oscillator
Start-up Timer
8
RD3/SCK/SCL
RD4/FLTA(2)
RD5/PWM4(4)
RD6/PWM6
Power-on
Reset
8
T1OSO
4X PLL
ALU<8>
Watchdog
Timer
RD7/PWM7
8
Precision
Band Gap
Reference
Brown-out
Reset
PORTE
RE0/AN6
Power-Managed
Mode Logic
MCLR/VPP
RE1/AN7
RE2/AN8
INTRC
OSC
MCLR/VPP/RE3(1)
VDD, VSS
Timer0
HS 10-Bit
ADC
Timer1
Timer2
Timer5
AVDD, AVSS
Synchronous
Serial Port
CCP1
CCP2
EUSART
Data EE
PCPWM
MFM
Note 1: RE3 is available only when MCLR is disabled.
2: RD4 is the alternate pin for FLTA.
3: RC3, RC4 and RC5 are alternate pins for T0CKI/T5CKI, SDI/SDA, SCK/SCL, respectively.
4: RD5 is the alternate pin for PWM4.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 13
PIC18F2331/2431/4331/4431
TABLE 1-2:
PIC18F2331/2431 PINOUT I/O DESCRIPTIONS
Pin Number
Pin Buffer
Pin Name
Description
SPDIP,
SOIC
Type Type
QFN
MCLR/VPP/RE3
MCLR
1
9
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
High-voltage ICSP™ programming enable pin.
Digital input. Available only when MCLR is disabled.
OSC1/CLKI/RA7
OSC1
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.
CLKO
RA6
I/O
TTL
General purpose I/O pin.
PORTA is a bidirectional I/O port.
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-/CAP1/INDX
RA2
AN2
VREF-
CAP1
INDX
I/O
TTL
Analog
Analog
ST
Digital I/O.
Analog input 2.
A/D reference voltage (low) input.
Input capture pin 1.
Quadrature Encoder Interface index input pin.
I
I
I
I
ST
RA3/AN3/VREF+/CAP2/QEA
5
6
2
3
RA3
AN3
VREF+
CAP2
QEA
I/O
TTL
Analog
Analog
ST
Digital I/O.
Analog input 3.
A/D reference voltage (high) input.
Input capture pin 2.
Quadrature Encoder Interface channel A input pin.
I
I
I
I
ST
RA4/AN4/CAP3/QEB
RA4
AN4
CAP3
QEB
I/O
TTL
Analog
ST
Digital I/O.
Analog input 4.
Input capture pin 3.
Quadrature Encoder Interface channel B input pin.
I
I
I
ST
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
OD = Open-Drain (no diode to VDD)
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
DS39616C-page 14
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 1-2:
PIC18F2331/2431 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Pin Name
Description
SPDIP,
QFN
SOIC
PORTB is a bidirectional I/O port. PORTB can be software
programmed for internal weak pull-ups on all inputs.
RB0/PWM0
RB0
21
22
23
24
25
18
19
20
21
22
I/O
O
TTL
TTL
Digital I/O.
PWM output 0.
PWM0
RB1/PWM1
RB1
I/O
O
TTL
TTL
Digital I/O.
PWM output 1.
PWM1
RB2/PWM2
RB2
I/O
O
TTL
TTL
Digital I/O.
PWM output 2.
PWM2
RB3/PWM3
RB3
I/O
O
TTL
TTL
Digital I/O.
PWM output 3.
PWM3
RB4/KBI0/PWM5
RB4
I/O
I
O
TTL
TTL
TTL
Digital I/O.
Interrupt-on-change pin.
PWM output 5.
KBI0
PWM5
RB5/KBI1/PWM4/PGM
26
23
RB5
I/O
I
O
TTL
TTL
TTL
ST
Digital I/O.
Interrupt-on-change pin.
PWM output 4.
KBI1
PWM4
PGM
I/O
Low-Voltage ICSP™ Programming entry pin.
RB6/KBI2/PGC
RB6
27
28
24
25
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
OD = Open-Drain (no diode to VDD)
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 15
PIC18F2331/2431/4331/4431
TABLE 1-2:
PIC18F2331/2431 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Pin Name
Description
SPDIP,
SOIC
Type Type
QFN
PORTC is a bidirectional I/O port.
RC0/T1OSO/T1CKI
RC0
11
12
8
I/O
O
I
ST
—
ST
Digital I/O.
Timer1 oscillator output.
Timer1 external clock input.
T1OSO
T1CKI
RC1/T1OSI/CCP2/FLTA
9
RC1
I/O
ST
CMOS
ST
Digital I/O.
Timer1 oscillator input.
Capture 2 input, Compare 2 output, PWM2 output.
Fault interrupt input pin.
T1OSI
CCP2
FLTA
I
I/O
I
ST
RC2/CCP1/FLTB
RC2
13
14
10
11
I/O
I/O
I
ST
ST
ST
Digital I/O.
CCP1
FLTB
Capture 1 input/Compare 1 output/PWM1 output.
Fault interrupt input pin.
RC3/T0CKI/T5CKI/INT0
RC3
I/O
ST
ST
ST
ST
Digital I/O.
T0CKI
T5CKI
INT0
I
I
I
Timer0 alternate clock input.
Timer5 alternate clock input.
External interrupt 0.
RC4/INT1/SDI/SDA
15
16
17
18
12
13
14
15
RC4
INT1
SDI
I/O
I
I
ST
ST
ST
ST
Digital I/O.
External interrupt 1.
SPI data in.
SDA
I/O
I2C™ data I/O.
RC5/INT2/SCK/SCL
RC5
INT2
SCK
SCL
I/O
I
I/O
I/O
ST
ST
ST
ST
Digital I/O.
External interrupt 2.
Synchronous serial clock input/output for SPI mode.
Synchronous serial clock input/output for I2C mode.
RC6/TX/CK/SS
RC6
TX
CK
SS
I/O
O
I/O
I
ST
—
ST
TTL
Digital I/O.
EUSART asynchronous transmit.
EUSART synchronous clock (see related RX/DT).
SPI slave select input.
RC7/RX/DT/SDO
RC7
RX
DT
I/O
I
I/O
O
ST
ST
ST
—
Digital I/O.
EUSART asynchronous receive.
EUSART synchronous data (see related TX/CK).
SPI data out.
SDO
VSS
VDD
8, 19 5, 16
7, 20 4, 17
P
P
—
—
Ground reference for logic and I/O pins.
Positive supply for logic and I/O pins.
CMOS = CMOS compatible input or output
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
OD = Open-Drain (no diode to VDD)
I
= Input
O
P
= Power
DS39616C-page 16
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 1-3:
Pin Name
PIC18F4331/4431 PINOUT I/O DESCRIPTIONS
Pin Number
Pin Buffer
Type Type
Description
PDIP TQFP QFN
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
ST
VPP
RE3
P
I
Programming voltage input.
Digital input. Available only when MCLR is disabled.
OSC1/CLKI/RA7
OSC1
13
30
32
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
14
31
33
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
OD = Open-Drain (no diode to VDD)
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: RC3 is the alternate pin for T0CKI/T5CKI; RC4 is the alternate pin for SDI/SDA; RC5 is the alternate pin
for SCK/SCL.
2: RD4 is the alternate pin for FLTA.
3: RD5 is the alternate pin for PWM4.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 17
PIC18F2331/2431/4331/4431
TABLE 1-3:
Pin Name
PIC18F4331/4431 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Description
PDIP TQFP QFN
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-/CAP1/
INDX
RA2
I/O
TTL
Analog
Analog
ST
Digital I/O.
Analog input 2.
A/D reference voltage (low) input.
Input capture pin 1.
Quadrature Encoder Interface index input pin.
AN2
I
I
I
I
VREF-
CAP1
INDX
ST
RA3/AN3/VREF+/
CAP2/QEA
RA3
5
22
22
I/O
TTL
Analog
Analog
ST
Digital I/O.
Analog input 3.
A/D reference voltage (high) input.
Input capture pin 2.
Quadrature Encoder Interface channel A input pin.
AN3
VREF+
CAP2
QEA
I
I
I
I
ST
RA4/AN4/CAP3/QEB
6
7
23
24
23
24
RA4
AN4
CAP3
QEB
I/O
TTL
Analog
ST
Digital I/O.
Analog input 4.
Input capture pin 3.
Quadrature Encoder Interface channel B input pin.
I
I
I
ST
RA5/AN5/LVDIN
RA5
I/O
TTL
Digital I/O.
AN5
LVDIN
I
I
Analog
Analog
Analog input 5.
Low-Voltage Detect input.
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
OD = Open-Drain (no diode to VDD)
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: RC3 is the alternate pin for T0CKI/T5CKI; RC4 is the alternate pin for SDI/SDA; RC5 is the alternate pin
for SCK/SCL.
2: RD4 is the alternate pin for FLTA.
3: RD5 is the alternate pin for PWM4.
DS39616C-page 18
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 1-3:
Pin Name
PIC18F4331/4431 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Description
PDIP TQFP QFN
PORTB is a bidirectional I/O port. PORTB can be software
programmed for internal weak pull-ups on all inputs.
RB0/PWM0
RB0
33
34
35
36
37
8
9
I/O
O
TTL
TTL
Digital I/O.
PWM output 0.
PWM0
RB1/PWM1
RB1
9
10
11
12
14
I/O
O
TTL
TTL
Digital I/O.
PWM output 1.
PWM1
RB2/PWM2
RB2
10
11
14
I/O
O
TTL
TTL
Digital I/O.
PWM output 2.
PWM2
RB3/PWM3
RB3
I/O
O
TTL
TTL
Digital I/O.
PWM output 3.
PWM3
RB4/KBI0/PWM5
RB4
I/O
I
O
TTL
TTL
TTL
Digital I/O.
Interrupt-on-change pin.
PWM output 5.
KBI0
PWM5
RB5/KBI1/PWM4/
PGM
38
15
15
RB5
KBI1
PWM4
PGM
I/O
I
O
TTL
TTL
TTL
ST
Digital I/O.
Interrupt-on-change pin.
PWM output 4.
I/O
Low-Voltage ICSP™ Programming entry pin.
RB6/KBI2/PGC
RB6
39
40
16
17
16
17
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
OD = Open-Drain (no diode to VDD)
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: RC3 is the alternate pin for T0CKI/T5CKI; RC4 is the alternate pin for SDI/SDA; RC5 is the alternate pin
for SCK/SCL.
2: RD4 is the alternate pin for FLTA.
3: RD5 is the alternate pin for PWM4.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 19
PIC18F2331/2431/4331/4431
TABLE 1-3:
Pin Name
PIC18F4331/4431 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Description
PDIP TQFP QFN
PORTC is a bidirectional I/O port.
RC0/T1OSO/T1CKI
RC0
15
16
32
35
34
35
I/O
O
I
ST
—
ST
Digital I/O.
Timer1 oscillator output.
Timer1 external clock input.
T1OSO
T1CKI
RC1/T1OSI/CCP2/
FLTA
RC1
I/O
ST
CMOS
ST
Digital I/O.
Timer1 oscillator input.
Capture 2 input, Compare 2 output, PWM2 output.
Fault interrupt input pin.
T1OSI
CCP2
FLTA
I
I/O
I
ST
RC2/CCP1/FLTB
RC2
17
18
36
37
36
37
I/O
I/O
I
ST
ST
ST
Digital I/O.
CCP1
FLTB
Capture 1 input/Compare 1 output/PWM1 output.
Fault interrupt input pin.
RC3/T0CKI/T5CKI/
INT0
RC3
I/O
ST
ST
ST
ST
Digital I/O.
T0CKI(1)
T5CKI(1)
INT0
I
I
I
Timer0 alternate clock input.
Timer5 alternate clock input.
External interrupt 0.
RC4/INT1/SDI/SDA
23
24
25
26
42
43
44
1
42
43
44
1
RC4
I/O
I
I
ST
ST
ST
ST
Digital I/O.
INT1
External interrupt 1.
SPI data in.
SDI(1)
SDA(1)
I/O
I2C™ data I/O.
RC5/INT2/SCK/SCL
RC5
I/O
I
I/O
I/O
ST
ST
ST
ST
Digital I/O.
External interrupt 2.
INT2
SCK(1)
SCL(1)
Synchronous serial clock input/output for SPI mode.
Synchronous serial clock input/output for I2C mode.
RC6/TX/CK/SS
RC6
TX
CK
SS
I/O
O
I/O
I
ST
—
ST
ST
Digital I/O.
EUSART asynchronous transmit.
EUSART synchronous clock (see related RX/DT).
SPI slave select input.
RC7/RX/DT/SDO
RC7
RX
DT
I/O
I
I/O
O
ST
ST
ST
—
Digital I/O.
EUSART asynchronous receive.
EUSART synchronous data (see related TX/CK).
SPI data out.
SDO
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
OD = Open-Drain (no diode to VDD)
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: RC3 is the alternate pin for T0CKI/T5CKI; RC4 is the alternate pin for SDI/SDA; RC5 is the alternate pin
for SCK/SCL.
2: RD4 is the alternate pin for FLTA.
3: RD5 is the alternate pin for PWM4.
DS39616C-page 20
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 1-3:
Pin Name
PIC18F4331/4431 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Description
PDIP TQFP QFN
PORTD is a bidirectional I/O port.
RD0/T0CKI/T5CKI
RD0
19
38
38
I/O
I
I
ST
ST
ST
Digital I/O.
Timer0 external clock input.
Timer5 input clock.
T0CKI
T5CKI
RD1/SDO
RD1
20
21
39
40
39
40
I/O
O
ST
—
Digital I/O.
SPI data out.
SDO
RD2/SDI/SDA
RD2
I/O
I
I/O
ST
ST
ST
Digital I/O.
SDI
SDA
SPI data in.
I2C™ data I/O.
RD3/SCK/SCL
RD3
22
41
41
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.
RD4/FLTA
RD4
27
28
29
30
2
3
4
5
2
3
4
5
I/O
I
ST
ST
Digital I/O.
Fault interrupt input pin.
FLTA(2)
RD5/PWM4
RD5
I/O
O
ST
TTL
Digital I/O.
PWM output 4.
PWM4(3)
RD6/PWM6
RD6
I/O
O
ST
TTL
Digital I/O.
PWM output 6.
PWM6
RD7/PWM7
RD7
I/O
O
ST
TTL
Digital I/O.
PWM output 7.
PWM7
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
OD = Open-Drain (no diode to VDD)
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: RC3 is the alternate pin for T0CKI/T5CKI; RC4 is the alternate pin for SDI/SDA; RC5 is the alternate pin
for SCK/SCL.
2: RD4 is the alternate pin for FLTA.
3: RD5 is the alternate pin for PWM4.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 21
PIC18F2331/2431/4331/4431
TABLE 1-3:
Pin Name
PIC18F4331/4431 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number
Pin Buffer
Type Type
Description
PDIP TQFP QFN
PORTE is a bidirectional I/O port.
RE0/AN6
RE0
8
9
25
26
27
25
26
27
I/O
I
ST
Analog
Digital I/O.
Analog input 6.
AN6
RE1/AN7
RE1
I/O
I
ST
Analog
Digital I/O.
Analog input 7.
AN7
RE2/AN8
RE2
10
I/O
I
ST
Analog
Digital I/O.
Analog input 8.
AN8
VSS
VDD
NC
12, 6, 29 6, 30,
31 31
11, 7, 28 7, 8,
P
—
Ground reference for logic and I/O pins.
P
—
Positive supply for logic and I/O pins.
32
28, 29
12,13, 13
33, 34
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
= Output
OD = Open-Drain (no diode to VDD)
—
NC
NC No connect.
CMOS = CMOS compatible input or output
I
= Input
O
P
= Power
Note 1: RC3 is the alternate pin for T0CKI/T5CKI; RC4 is the alternate pin for SDI/SDA; RC5 is the alternate pin
for SCK/SCL.
2: RD4 is the alternate pin for FLTA.
3: RD5 is the alternate pin for PWM4.
DS39616C-page 22
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 2-1:
CRYSTAL/CERAMIC
RESONATOROPERATION
(XT, LP, HS OR HSPLL
CONFIGURATION)
2.0
2.1
OSCILLATOR
CONFIGURATIONS
Oscillator Types
(1)
C1
OSC1
The PIC18F2331/2431/4331/4431 devices can be
operated in 10 different oscillator modes. The user can
program the Configuration bits FOSC3:FOSC0 in
Configuration Register 1H to select one of these 10
modes:
To
Internal
Logic
XTAL
(3)
RF
Sleep
(2)
RS
1. LP
Low-Power Crystal
(1)
PIC18FXXXX
C2
2. XT
Crystal/Resonator
OSC2
3. HS
High-Speed Crystal/Resonator
Note 1: See Table 2-1 and Table 2-2 for initial values of
4. HSPLL
High-Speed Crystal/Resonator
with PLL Enabled
C1 and C2.
2: A series resistor (RS) may be required for AT
5. RC
External Resistor/Capacitor with
FOSC/4 Output on RA6
strip cut crystals.
3: RF varies with the oscillator mode chosen.
6. RCIO
7. INTIO1
8. INTIO2
External Resistor/Capacitor with
I/O on RA6
TABLE 2-1:
CAPACITOR SELECTION FOR
CERAMIC RESONATORS
Internal Oscillator with FOSC/4
Output on RA6 and I/O on RA7
Internal Oscillator with I/O on RA6
and RA7
Typical Capacitor Values Used:
Mode
Freq
OSC1
OSC2
9. EC
External Clock with FOSC/4 Output
External Clock with I/O on RA6
10. ECIO
XT
455 kHz
2.0 MHz
4.0 MHz
56 pF
47 pF
33 pF
56 pF
47 pF
33 pF
2.2
Crystal Oscillator/Ceramic
Resonators
HS
8.0 MHz
16.0 MHz
27 pF
22 pF
27 pF
22 pF
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.
These capacitors were tested with the resonators
listed below for basic start-up and operation. These
values are not optimized.
The oscillator design requires the use of a parallel cut
crystal.
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.
Note:
Use of a series cut crystal may give a
frequency out of the crystal
manufacturers’ specifications.
See the notes following Table 2-2 for additional
information.
Resonators Used:
455 kHz
2.0 MHz
4.0 MHz
8.0 MHz
16.0 MHz
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 23
PIC18F2331/2431/4331/4431
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
HS
32 kHz
200 kHz
1 MHz
4 MHz
4 MHz
8 MHz
20 MHz
33 pF
15 pF
33 pF
27 pF
27 pF
22 pF
15 pF
33 pF
15 pF
33 pF
27 pF
27 pF
22 pF
15 pF
OSC1
Clock from
Ext. System
PIC18FXXXX
(HS Mode)
OSC2
Open
2.3
HSPLL
Capacitor values are for design guidance only.
A Phase Locked Loop (PLL) circuit is provided as an
option for users who wish to use a lower frequency
crystal 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.
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.
The HSPLL mode makes use of the HS Oscillator
mode for frequencies up to 10 MHz. A PLL then multi-
plies the oscillator output frequency by 4 to produce an
internal clock frequency up to 40 MHz.
See the notes following this table for additional
information.
The PLL is enabled only when the oscillator Configura-
tion bits are programmed for HSPLL mode. If
programmed for any other mode, the PLL is not
enabled.
Crystals Used:
32 kHz
200 kHz
1 MHz
4 MHz
8 MHz
20 MHz
FIGURE 2-3:
PLL BLOCK DIAGRAM
HS Osc Enable
PLL Enable
(from Configuration Register 1H)
Note 1: Higher capacitance increases the
stability of oscillator, but also increases
the start-up time.
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.
OSC2
OSC1
Phase
Comparator
HS Mode
Crystal
Osc
FIN
FOUT
3: Since each resonator/crystal has its own
characteristics, the user should consult
the resonator/crystal manufacturer for
Loop
Filter
appropriate
values
of
external
components.
÷4
VCO
SYSCLK
4: Rs may be required to avoid overdriving
crystals with low drive level specification.
5: Always verify oscillator performance over
the VDD and temperature range that is
expected for the application.
DS39616C-page 24
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
2.4
External Clock Input
2.5
RC Oscillator
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.
For timing insensitive applications, the RC and RCIO
device options offer additional cost savings. The RC
oscillator frequency is a function of the supply voltage,
the resistor (REXT) and capacitor (CEXT) values and the
operating temperature. In addition to this, the oscillator
frequency will vary from unit-to-unit due to normal
manufacturing variation. Furthermore, the difference in
lead frame capacitance between package types will
also affect the oscillation frequency, especially for low
CEXT values. The user also needs to take into account
variation due to tolerance of external R and C
components used. Figure 2-6 shows how the R/C
combination is connected.
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 2-4 shows the pin connections for the EC
Oscillator mode.
FIGURE 2-4:
EXTERNAL CLOCK INPUT
OPERATION
(EC CONFIGURATION)
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.
OSC1/CLKI
Clock from
Ext. System
PIC18FXXXX
OSC2/CLKO
FOSC/4
FIGURE 2-6:
RC OSCILLATOR MODE
VDD
The ECIO Oscillator mode functions like the EC mode,
except that the OSC2 pin becomes an additional
general purpose I/O pin. The I/O pin becomes bit 6 of
PORTA (RA6). Figure 2-5 shows the pin connections
for the ECIO Oscillator mode.
REXT
Internal
OSC1
Clock
CEXT
VSS
PIC18FXXXX
FIGURE 2-5:
EXTERNAL CLOCK INPUT
OPERATION
(ECIO CONFIGURATION)
OSC2/CLKO
FOSC/4
Recommended values: 3 kΩ ≤ REXT ≤ 100 kΩ
CEXT > 20 pF
OSC1/CLKI
PIC18FXXXX
I/O (OSC2)
Clock from
Ext. System
The RCIO Oscillator mode (Figure 2-7) 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).
RA6
FIGURE 2-7:
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
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 25
PIC18F2331/2431/4331/4431
2.6.2
INTRC OUTPUT FREQUENCY
2.6
Internal Oscillator Block
The internal oscillator block is calibrated at the factory
to produce an INTOSC output frequency of 8.0 MHz.
This changes the frequency of the INTRC source from
its nominal 31.25 kHz. Peripherals and features that
depend on the INTRC source will be affected by this
shift in frequency.
The PIC18F2331/2431/4331/4431 devices include an
internal oscillator block, which generates two different
clock signals; either can be used as the system’s clock
source. This can eliminate the need for external
oscillator circuits on the OSC1 and/or OSC2 pins.
The main output (INTOSC) is an 8 MHz clock source,
which can be used to directly drive the system clock. It
also drives a postscaler, which can provide a range of
clock frequencies from 125 kHz to 4 MHz. The
INTOSC output is enabled when a system clock
frequency from 125 kHz to 8 MHz is selected.
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). The tuning sensitivity is constant
throughout the tuning range.
The other clock source is the internal RC oscillator
(INTRC), which provides a 31 kHz output. The INTRC
oscillator is enabled by selecting the internal oscillator
block as the system clock source, or when any of the
following are enabled:
When the OSCTUNE register is modified, the INTOSC
and INTRC frequencies will begin shifting to the new
frequency. The INTRC clock will reach the new
frequency within
8 clock cycles (approximately
• Power-up Timer
8 * 32 μs = 256 μs). The INTOSC clock will stabilize
within 1 ms. Code execution continues during this shift.
There is no indication that the shift has occurred. Oper-
ation of features that depend on the INTRC clock
source frequency, such as the WDT, Fail-Safe Clock
Monitor and peripherals, will also be affected by the
change in frequency.
• Fail-Safe Clock Monitor
• Watchdog Timer
• Two-Speed Start-up
These features are discussed in greater detail in
Section 22.0 “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 (Register 2-2).
2.6.1
INTIO MODES
Using the internal oscillator as the clock source can
eliminate the need for up to two external oscillator pins,
which can then be used for digital I/O. Two distinct
configurations are available:
• 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.
DS39616C-page 26
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 2-1:
OSCTUNE: OSCILLATOR TUNING REGISTER
U-0
—
U-0
—
R/W-0
TUN5
R/W-0
TUN4
R/W-0
TUN3
R/W-0
TUN2
R/W-0
TUN1
R/W-0
TUN0
bit 7
bit 0
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
bit 7-6
bit 5-0
Unimplemented: Read as ‘0’
TUN5:TUN0: Frequency Tuning bits
011111= Maximum frequency
•
•
•
•
000001
000000= Center frequency. Oscillator module is running at the calibrated frequency.
111111
•
•
•
•
100000= Minimum frequency
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 27
PIC18F2331/2431/4331/4431
2.7.1
OSCILLATOR CONTROL REGISTER
2.7
Clock Sources and Oscillator
Switching
The OSCCON register (Register 2-2) controls several
aspects of the system clock’s operation, both in full
power operation and in power-managed modes.
Like previous PIC18 devices, the PIC18F2331/2431/
4331/4431 devices include a feature that allows the sys-
tem clock source to be switched from the main oscillator
to an alternate low-frequency clock source. PIC18F2331/
2431/4331/4431 devices offer two alternate clock
sources. When enabled, these give additional options for
switching to the various power-managed operating
modes.
The System Clock Select bits, SCS1:SCS0, select the
clock source that is used when the device is operating
in power-managed modes. The available clock sources
are the primary clock (defined in Configuration Register
1H), the secondary clock (Timer1 oscillator) and the
internal oscillator block. The clock selection has no
effect until a SLEEP instruction is executed and the
device enters a power-managed mode of operation.
The SCS bits are cleared on all forms of Reset.
Essentially, there are three clock sources for these
devices:
• Primary oscillators
The Internal Oscillator Select bits, IRCF2:IRCF0, select
the frequency output of the internal oscillator block that
is used to drive the system clock. The choices are the
INTRC source, the INTOSC source (8 MHz) or one of
the six frequencies derived from the INTOSC
postscaler (125 kHz to 4 MHz). If the internal oscillator
block is supplying the system clock, changing the
states of these bits will have an immediate change on
the internal oscillator’s output.
• Secondary oscillators
• Internal oscillator block
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 on POR by the contents
of Configuration Register 1H. The details of these
modes are covered earlier in this chapter.
The OSTS, IOFS and T1RUN bits indicate which clock
source is currently providing the system clock. The OSTS
indicates that the Oscillator Start-up Timer has timed out,
and the primary clock is providing the system clock in
primary clock modes. The IOFS bit indicates when the
internal oscillator block has stabilized, and is providing
the system clock in RC Clock modes. The T1RUN bit
(T1CON<6>) indicates when the Timer1 oscillator is
providing the system 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 system clock, or the internal oscillator
block has just started and is not yet stable.
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.
PIC18F2331/2431/4331/4431 devices offer only 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
(RTC).
Most often, a 32.768 kHz watch crystal is connected
between the RC0/T1OSO and RC1/T1OSI pins. Like
the LP mode oscillator circuit, loading capacitors are
also connected from each pin to ground.
The IDLEN bit controls the selective shutdown of the
controller’s CPU in power-managed modes. The use of
these bits is discussed in more detail in Section 3.0
“Power-Managed Modes”
The Timer1 oscillator is discussed in greater detail in
Section 12.2 “Timer1 Oscillator”.
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.
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
register (T1CON<3>). If the Timer1
oscillator is not enabled, then any attempt
to select a secondary clock source when
executing a SLEEP instruction will be
ignored.
The clock sources for the PIC18F2331/2431/4331/4431
devices are shown in Figure 2-8. See Section 12.0
“Timer1 Module” for further details of the Timer1
oscillator. See Section 22.1 “Configuration Bits” for
Configuration register details.
2: It is recommended that the Timer1
oscillator be operating and stable before
executing the SLEEPinstruction, or a very
long delay may occur while the Timer1
oscillator starts.
DS39616C-page 28
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 2-8:
PIC18F2331/2431/4331/4431 CLOCK DIAGRAM
Clock
Control
PIC18F2331/2431/4331/4431
CONFIG1H<3:0>
HSPLL
OSCCON<1:0>
Peripherals
Primary Oscillator
OSC2
4 x PLL
Sleep
LP, XT, HS, RC, EC
OSC1
Secondary Oscillator
T1OSC
T1OSO
Clock Source Option
for other Modules
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
1 MHz
100
011
010
001
000
500 kHz
250 kHz
125 kHz
31 kHz
8 MHz
(INTOSC)
INTRC
Source
WDT, FSCM
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 29
PIC18F2331/2431/4331/4431
REGISTER 2-2:
OSCCON: OSCILLATOR CONTROL REGISTER
R/W-0
IDLEN
bit 7
R/W-0
IRCF2
R/W-0
IRCF1
R/W-0
IRCF0
R(1)
R-0
R/W-0
SCS1
R/W-0
SCS0
OSTS
IOFS
bit 0
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
bit 7
IDLEN: Idle Enable bit
1= Idle mode enabled; CPU core is not clocked in power-managed modes
0= Run mode enabled; CPU core is clocked in power-managed modes
bit 6-4
IRCF2:IRCF0: Internal Oscillator Frequency Select bits
111= 8 MHz (8 MHz source drives clock directly)
110= 4 MHz (default)
101= 2 MHz
100= 1 MHz
011= 500 kHz
010= 250 kHz
001= 125 kHz
000= 31 kHz (INTRC source drives clock directly)
bit 3
OSTS: Oscillator Start-up Timer Time-out Status bit(1)
1= Oscillator Start-up Timer time-out has expired; primary oscillator is running
0= Oscillator Start-up Timer time-out is running; primary oscillator is not ready
bit 2
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 (RC modes)
01= Timer1 oscillator (Secondary modes)
00= Primary oscillator (Sleep and PRI_IDLE modes)
Note 1: Depends on the state of the IESO bit in Configuration Register 1H.
DS39616C-page 30
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
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).
2.7.2
OSCILLATOR TRANSITIONS
The PIC18F2331/2431/4331/4431 devices contain
circuitry to prevent clocking “glitches” when switching
between clock sources. A short pause in the system
clock occurs during the clock switch. The length of this
pause is between 8 and 9 clock periods of the new
clock source. This ensures that the new clock source is
stable and that its pulse width will not be less than the
shortest pulse width of the two clock sources.
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 require a system clock source (i.e., SSP slave,
INTx pins, A/D conversions and others).
Clock transitions are discussed in greater detail in
Section 3.1.2 “Entering Power-Managed Modes”.
2.8
Effects of Power-Managed Modes
on the Various Clock Sources
2.9
Power-up Delays
Power-up delays are controlled by two timers, so that no
external Reset circuitry is required for most applications.
The delays ensure that the device is kept in Reset until
the device power supply is stable under normal
circumstances, and the primary clock is operating and
stable. For additional information on power-up delays,
see Section 4.1 “Power-on Reset (POR)” through
Section 4.5 “Brown-out Reset (BOR)”.
When the device executes a SLEEP instruction, the
system is switched to one of the power-managed
modes, depending on the state of the IDLEN and
SCS1:SCS0 bits of the OSCCON register. See
Section 3.0 “Power-Managed Modes” for details.
When PRI_IDLE mode is selected, the designated
primary 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.
The first timer is the Power-up Timer (PWRT), which
provides a fixed delay on power-up (parameter 33,
Table 25-8), if enabled, in Configuration Register 2L.
The second timer is the Oscillator Start-up Timer
(OST), intended to keep the chip in Reset until the crys-
tal 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.
In secondary clock modes (SEC_RUN and
SEC_IDLE), the Timer1 oscillator is operating and
providing the system clock. The Timer1 oscillator may
also run in all power-managed modes if required to
clock Timer1.
In internal oscillator modes (RC_RUN and RC_IDLE),
the internal oscillator block provides the system clock
source. The INTRC output can be used directly to
provide the system clock and may be enabled to
support various special features, regardless of the
power-managed mode (see Section 22.2 “Watchdog
Timer (WDT)” through Section 22.4 “Fail-Safe Clock
Monitor”). The INTOSC output at 8 MHz may be used
directly to clock the system, or may be divided down
first. The INTOSC output is disabled if the system clock
is provided directly from the INTRC output.
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.
There is a delay of 5 to 10 μs 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.
TABLE 2-3:
OSC1 AND OSC2 PIN STATES IN SLEEP MODE
OSC Mode
OSC1 Pin
OSC2 Pin
RC, INTIO1
Floating, external resistor
should pull high
At logic low (clock/4 output)
RCIO, INTIO2
Floating, external resistor
should pull high
Configured as PORTA, bit 6
ECIO
Floating, pulled by external clock
Floating, pulled by external clock
Configured as PORTA, bit 6
At logic low (clock/4 output)
EC
LP, XT and HS
Feedback inverter disabled at
quiescent voltage level
Feedback inverter disabled at
quiescent voltage level
Note:
See Table 4-1 in Section 4.0 “Reset” for time-outs due to Sleep and MCLR Reset.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 31
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 32
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
For PIC18F2331/2431/4331/4431 devices, the power-
3.0
POWER-MANAGED MODES
managed modes are invoked by using the existing
SLEEP instruction. All modes exit to PRI_RUN mode
when triggered by an interrupt, a Reset or a WDT time-
out (PRI_RUN mode is the normal full power execution
mode; the CPU and peripherals are clocked by the
primary oscillator source). In addition, power-managed
Run modes may also exit to Sleep mode or their
corresponding Idle mode.
The PIC18F2331/2431/4331/4431 devices offer a total
of six operating modes for more efficient power
management (see Table 3-1). These operating modes
provide a variety of options for selective power
conservation in applications where resources may be
limited (i.e., battery-powered devices).
There are three categories of power-managed modes:
• Sleep mode
• Idle modes
• Run modes
3.1
Selecting Power-Managed Modes
Selecting a power-managed mode requires deciding if
the CPU is to be clocked or not, and selecting a clock
source. The IDLEN bit controls CPU clocking, while the
SCS1:SCS0 bits select a clock source. The individual
modes, bit settings, clock sources and affected
modules are summarized in Table 3-1.
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 INTOSC multiplexer);
the Sleep mode does not use a clock source.
The clock switching feature offered in other PIC18
devices (i.e., using the Timer1 oscillator in place of the
primary oscillator), and the Sleep mode offered by all
PIC® devices (where all system clocks are stopped), are
both offered in the PIC18F2331/2431/4331/4431
devices (SEC_RUN and Sleep modes, respectively).
However, additional power-managed modes are
available that allow the user greater flexibility in deter-
mining what portions of the device are operating. The
power-managed modes are event driven; that is, some
specific event must occur for the device to enter or (more
particularly) exit these operating modes.
3.1.1
CLOCK SOURCES
The clock source is selected by setting the SCS bits of
the OSCCON register. Three clock sources are avail-
able for use in power-managed Idle modes: the primary
clock (as configured in Configuration Register 1H), the
secondary clock (Timer1 oscillator) and the internal
oscillator block. The secondary and internal oscillator
block sources are available for the power-managed
modes (PRI_RUN mode is the normal full power
execution mode; the CPU and peripherals are clocked
by the primary oscillator source).
TABLE 3-1:
Mode
POWER-MANAGED MODES
OSCCON<7,1:0>
Module Clocking
Available Clock and Oscillator Source
IDLEN SCS1:SCS0
CPU
Peripherals
Sleep
0
0
00
00
Off
Off
None – All clocks are disabled
Primary – LP, XT, HS, HSPLL, RC, EC, INTRC(1)
PRI_RUN
Clocked
Clocked
This is the normal full power execution mode.
SEC_RUN
RC_RUN
PRI_IDLE
SEC_IDLE
RC_IDLE
0
0
1
1
1
01
1x
00
01
1x
Clocked
Clocked
Off
Clocked
Clocked
Clocked
Clocked
Clocked
Secondary – Timer1 Oscillator
Internal Oscillator Block(1)
Primary – LP, XT, HS, HSPLL, RC, EC
Secondary – Timer1 Oscillator
Internal Oscillator Block(1)
Off
Off
Note 1: Includes INTOSC and INTOSC postscaler, as well as the INTRC source.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 33
PIC18F2331/2431/4331/4431
3.1.2
ENTERING POWER-MANAGED
MODES
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.
In general, entry, exit and switching between power-
managed clock sources requires clock source
switching. In each case, the sequence of events is the
same.
Any change in the power-managed mode begins with
loading the OSCCON register and executing a SLEEP
instruction. The SCS1:SCS0 bits select one of three
power-managed clock sources; the primary clock (as
defined in Configuration Register 1H), the secondary
clock (the Timer1 oscillator) and the internal oscillator
block (used in RC modes). Modifying the SCS bits will
have no effect until a SLEEP instruction is executed.
Entry to the power-managed mode is triggered by the
execution of a SLEEPinstruction.
2: Executing a SLEEP instruction does not
necessarily place the device into Sleep
mode. Executing a SLEEP instruction is
simply a trigger to place the controller into
a power-managed mode selected by the
OSCCON register, one of which is Sleep
mode.
3.1.3
MULTIPLE SLEEP COMMANDS
The power-managed mode that is invoked with the
SLEEPinstruction is determined by the settings of the
IDLEN and SCS bits at the time the instruction is exe-
cuted. If another SLEEP instruction is executed, the
device will enter the power-managed mode specified
by these same bits at that time. If the bits have
changed, the device will enter the new power-managed
mode specified by the new bit settings.
Figure 3-5 shows how the system is clocked while
switching from the primary clock to the Timer1 oscilla-
tor. When the SLEEPinstruction is executed, clocks to
the device are stopped at the beginning of the next
instruction cycle. Eight clock cycles from the new clock
source are counted to synchronize with the new clock
source. After eight clock pulses from the new clock
source are counted, clocks from the new clock source
resume clocking the system. The actual length of the
pause is between eight and nine clock periods from the
new clock source. This ensures that the new clock
source is stable and that its pulse width will not be less
than the shortest pulse width of the two clock sources.
3.1.4
COMPARISONS BETWEEN RUN
AND IDLE MODES
Clock source selection for the Run modes is identical to
the corresponding Idle modes. When a SLEEPinstruc-
tion is executed, the SCS bits in the OSCCON register
are used to switch to a different clock source. As a
result, if there is a change of clock source at the time a
SLEEPinstruction is executed, a clock switch will occur.
Three bits indicate the current clock source: OSTS and
IOFS in the OSCCON register, and T1RUN in the
T1CON register. Only one of these bits will be set while
in a power-managed mode other than PRI_RUN. When
the OSTS bit is set, the primary clock is providing the
system clock. When the IOFS bit is set, the INTOSC
output is providing a stable 8 MHz clock source and is
providing the system clock. When the T1RUN bit is set,
the Timer1 oscillator is providing the system clock. If
none of these bits are set, then either the INTRC clock
source is clocking the system, or the INTOSC source is
not yet stable.
In Idle modes, the CPU is not clocked and is not run-
ning. In Run modes, the CPU is clocked and executing
code. This difference modifies the operation of the
WDT when it times out. In Idle modes, a WDT time-out
results in a wake from power-managed modes. In Run
modes, a WDT time-out results in a WDT Reset (see
Table 3-2).
During a wake-up from an Idle mode, the CPU starts
executing code by entering the corresponding Run
mode until the primary clock becomes ready. When the
primary clock becomes ready, the clock source is auto-
matically switched to the primary clock. The IDLEN and
SCS bits are unchanged during and after the wake-up.
If the internal oscillator block is configured as the
primary clock source in Configuration Register 1H, 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 a power-managed RC mode
(same frequency) would clear the OSTS bit.
Figure 3-2 shows how the system is clocked during the
clock source switch. The example assumes the device
was in SEC_IDLE or SEC_RUN mode when a wake is
triggered (the primary clock was configured in HSPLL
mode).
DS39616C-page 34
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 3-2:
COMPARISON BETWEEN POWER-MANAGED MODES
Clock During Wake-up
(while primary clock source
becomes ready)
Power-Managed
Mode
WDT Time-out
Causes a ...
Peripherals are
Clocked by ...
CPU is Clocked by ...
Sleep
Not clocked (not running) Wake-up
Not clocked
None or INTOSC multiplexer if
Two-Speed Start-up or
Fail-Safe Clock Monitor are
enabled.
Any Idle mode
Any Run mode
Not clocked (not running) Wake-up
Primary, secondary or
INTOSC multiplexer
Unchanged from Idle mode
(CPU operates as in
corresponding Run mode).
Secondary or INTOSC
multiplexer
Reset
Secondary or INTOSC Unchanged from Run mode.
multiplexer
If the Idle Enable bit, IDLEN (OSCCON<7>), is set to a
‘1’ when a SLEEP instruction is executed, the
peripherals will be clocked from the clock source
selected using the SCS1:SCS0 bits; however, the CPU
will not be clocked. 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.
3.2
Sleep Mode
The power-managed Sleep mode in the PIC18F2331/
2431/4331/4431 devices is identical to that offered in
all other PIC® microcontrollers. It is entered by clearing
the IDLEN and SCS1:SCS0 bits (this is the Reset state)
and executing the SLEEPinstruction. This shuts down
the primary oscillator and the OSTS bit is cleared (see
Figure 3-1).
When a wake event occurs, CPU execution is delayed
approximately 10 μs while it becomes ready to execute
code. When the CPU begins executing code, it is
clocked by the same clock source as was selected in
the power-managed mode (i.e., when waking from
RC_IDLE mode, the internal oscillator block will clock
the CPU and peripherals until the primary clock source
becomes ready – this is essentially RC_RUN mode).
This continues until the primary clock source becomes
ready. When the primary clock becomes ready, the
OSTS bit is set and the system clock source is
switched to the primary clock (see Figure 3-4). The
IDLEN and SCS bits are not affected by the wake-up.
When a wake event occurs in Sleep mode (by interrupt,
Reset, or WDT time-out), the system will not be clocked
until the primary clock source becomes ready (see
Figure 3-2), 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 22.0
“Special Features of the CPU”). In either case, the
OSTS bit is set when the primary clock provides the
system clocks. The IDLEN and SCS bits are not
affected by the wake-up.
3.3
Idle Modes
While in any Idle mode or the Sleep mode, a WDT
time-out will result in a WDT wake-up to full power
operation.
The IDLEN bit allows the controller’s CPU to be
selectively shut down while the peripherals continue to
operate. Clearing IDLEN allows the CPU to be clocked.
Setting IDLEN disables clocks to the CPU, effectively
stopping program execution (see Register 2-2). The
peripherals continue to be clocked regardless of the
setting of the IDLEN bit.
There is one exception to how the IDLEN bit functions.
When all the low-power OSCCON bits are cleared
(IDLEN:SCS1:SCS0 = 000), the device enters Sleep
mode upon execution of the SLEEPinstruction. This is
both the Reset state of the OSCCON register and the
setting that selects Sleep mode. This maintains
compatibility with other PIC devices that do not offer
power-managed modes.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 35
PIC18F2331/2431/4331/4431
FIGURE 3-1:
TIMING TRANSITION FOR ENTRY TO SLEEP MODE
Q1 Q2 Q3 Q4 Q1
OSC1
CPU
Clock
Peripheral
Clock
Sleep
Program
Counter
PC
PC + 2
FIGURE 3-2:
TRANSITION TIMING FOR WAKE FROM SLEEP (HSPLL)
Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Q1 Q2 Q3 Q4 Q1 Q2
OSC1
(1)
(1)
TOST
TPLL
PLL Clock
Output
CPU Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
PC + 4
PC + 6
PC + 8
Wake Event
Note 1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
OSTS bit Set
DS39616C-page 36
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
When a wake event occurs, the CPU is clocked from the
primary clock source. A delay of approximately 10 μs 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 3-4).
3.3.1
PRI_IDLE MODE
This mode is unique among the three low-power Idle
modes, in that it does not disable the primary system
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.
PRI_IDLE mode is entered by setting the IDLEN bit,
clearing the SCS bits and executing a SLEEPinstruc-
tion. Although the CPU is disabled, the peripherals
continue to be clocked from the primary clock source
specified in Configuration Register 1H. The OSTS bit
remains set in PRI_IDLE mode (see Figure 3-3).
FIGURE 3-3:
TRANSITION TIMING TO PRI_IDLE MODE
Q3
Q4
Q1
Q1
Q2
OSC1
CPU Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
FIGURE 3-4:
TRANSITION TIMING FOR WAKE FROM PRI_IDLE MODE
Q1
Q3
Q4
Q2
OSC1
CPU Start-up Delay
CPU Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
Wake Event
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 37
PIC18F2331/2431/4331/4431
When a wake event occurs, the peripherals continue to
be clocked from the Timer1 oscillator. After a 10 μs
delay following the wake event, the CPU begins execut-
ing code, being clocked by the Timer1 oscillator. The
microcontroller operates in SEC_RUN mode until the
primary clock becomes ready. When the primary clock
becomes ready, a clock switch back to the primary clock
occurs (see Figure 3-6). When the clock switch is com-
plete, the T1RUN bit is cleared, the OSTS bit is set and
the primary clock is providing the system clock. The
IDLEN and SCS bits are not affected by the wake-up;
the Timer1 oscillator continues to run.
3.3.2
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 by setting the Idle bit,
modifying SCS1:SCS0 = 01 and executing a SLEEP
instruction. When the clock source is switched (see
Figure 3-5) to the Timer1 oscillator, the primary
oscillator is shut down, the OSTS bit is cleared and the
T1RUN bit is set.
Note:
The Timer1 oscillator should already be
running prior to entering SEC_IDLE mode.
If the T1OSCEN bit is not set when the
SLEEP instruction is executed, a forced
NOPwill be executed instead 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.
FIGURE 3-5:
TIMING TRANSITION FOR ENTRY TO SEC_IDLE MODE
Q1 Q2 Q3 Q4 Q1
T1OSI
OSC1
1
2
3
4
5
6
7
8
Clock Transition
CPU
Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
FIGURE 3-6:
TIMING TRANSITION FOR WAKE FROM SEC_RUN MODE (HSPLL)
Q3
Q4
Q1
Q2 Q3 Q4 Q1 Q2 Q3
Q1
Q2
T1OSI
OSC1
(1)
(1)
TPLL
TOST
PLL Clock
Output
1
2
3
4
5
6
7
8
Clock Transition
CPU Clock
Peripheral
Clock
Program
Counter
PC + 4
PC + 6
PC
PC + 2
OSTS bit Set
Wake from Interrupt Event
Note 1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
DS39616C-page 38
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
instruction was executed, and the INTOSC source was
already stable, the IOFS bit will remain set. If the IRCF
bits 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.
3.3.3
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.
When a wake event occurs, the peripherals continue to
be clocked from the INTOSC multiplexer. After a 10 μs
delay following the wake event, the CPU begins exe-
cuting code, being clocked by the INTOSC multiplexer.
The microcontroller operates in RC_RUN mode until
the primary clock becomes ready. When the primary
clock becomes ready, a clock switch back to the pri-
mary clock occurs (see Figure 3-8). When the clock
switch is complete, the IOFS bit is cleared, the OSTS
bit is set and the primary clock is providing the system
clock. 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.
This mode is entered by setting the IDLEN bit, setting
SCS1 (SCS0 is ignored) and executing a SLEEP
instruction. 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
(see Figure 3-7), the primary oscillator is shut down
and the OSTS bit is cleared.
If the IRCF bits are set to a non-zero value (thus
enabling the INTOSC output), the IOFS bit becomes
set after the INTOSC output becomes stable, in about
1 ms. Clocks to the peripherals continue while the
INTOSC source stabilizes. If the IRCF bits were
previously at a non-zero value before the SLEEP
FIGURE 3-7:
TIMING TRANSITION TO RC_IDLE MODE
Q1 Q2 Q3 Q4 Q1
1
2
3
4
5
6
7
8
INTRC
OSC1
Clock Transition
CPU
Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
FIGURE 3-8:
TIMING TRANSITION FOR WAKE FROM RC_RUN MODE (RC_RUN TO PRI_RUN)
Q3
Q4
Q1
Q2 Q3 Q4 Q1 Q2 Q3
Q4
Q1
Q2
INTOSC
Multiplexer
OSC1
(1)
TOST
(1)
TPLL
PLL Clock
Output
1
2
3
4
5
6
7
8
Clock Transition
CPU Clock
Peripheral
Clock
Program
Counter
PC + 4
PC + 6
PC
PC + 2
OSTS bit Set
Note 1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
Wake from Interrupt Event
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 39
PIC18F2331/2431/4331/4431
SEC_RUN mode is entered by clearing the IDLEN bit,
setting SCS1:SCS0 = 01 and executing a SLEEP
instruction. The system clock source is switched to the
Timer1 oscillator (see Figure 3-9), the primary oscilla-
tor is shut down, the T1RUN bit (T1CON<6>) is set and
the OSTS bit is cleared.
3.4
Run Modes
If the IDLEN bit is clear when a SLEEP instruction is
executed, the CPU and peripherals are both clocked
from the source selected using the SCS1:SCS0 bits.
While these operating modes may not afford the power
conservation of Idle or Sleep modes, they do allow the
device to continue executing instructions by using a
lower frequency clock source. RC_RUN mode also
offers the possibility of executing code at a frequency
greater than the primary clock.
Note:
The Timer1 oscillator should already be
running prior to entering SEC_RUN mode.
If the T1OSCEN bit is not set when the
SLEEP instruction is executed, a forced
NOPwill be executed instead and entry to
SEC_IDLE mode will not occur. If the
Timer1 oscillator is enabled, but not yet
running, system clocks will be delayed
until the oscillator has started. In such
situations, initial oscillator operation is far
from stable and unpredictable operation
may result.
Wake-up from a power-managed Run mode can be
triggered by an interrupt, or any Reset, to return to full
power operation. As the CPU is executing code in Run
modes, several additional exits from Run modes are
possible. They include exit to Sleep mode, exit to a
corresponding Idle mode and exit by executing a
RESET instruction. While the device is in any of the
power-managed Run modes, a WDT time-out will
result in a WDT Reset.
When a wake event occurs, 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 3-6). When the clock switch is com-
plete, the T1RUN bit is cleared, the OSTS bit is set and
the primary clock is providing the system clock. The
IDLEN and SCS bits are not affected by the wake-up;
the Timer1 oscillator continues to run.
3.4.1
PRI_RUN MODE
The PRI_RUN mode is the normal full power execution
mode. If the SLEEPinstruction is never executed, the
microcontroller operates in this mode (a SLEEPinstruc-
tion is executed to enter all other power-managed
modes). All other power-managed modes exit to
PRI_RUN mode when an interrupt or WDT time-out
occur.
Firmware can force an exit from SEC_RUN mode. By
clearing the T1OSCEN bit (T1CON<3>), an exit from
SEC_RUN back to normal full power operation is trig-
gered. The Timer1 oscillator will continue to run and
provide the system clock even though the T1OSCEN bit
is cleared. The primary clock is started. When the pri-
mary clock becomes ready, a clock switch back to the
primary clock occurs (see Figure 3-6). When the clock
switch is complete, the Timer1 oscillator is disabled, the
T1RUN bit is cleared, the OSTS bit is set and the
primary clock provides the system clock. The IDLEN
and SCS bits are not affected by the wake-up.
There is no entry to PRI_RUN mode. The OSTS bit is
set. The IOFS bit may be set if the internal oscillator
block is the primary clock source (see Section 2.7.1
“Oscillator Control Register”).
3.4.2
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.
FIGURE 3-9:
TIMING TRANSITION FOR ENTRY TO SEC_RUN MODE
Q1 Q2 Q3 Q4 Q1
Q2
Q3
Q4
Q1
Q2
Q3
1
2
3
4
5
6
7
8
T1OSI
OSC1
Clock Transition
CPU
Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
PC + 2
DS39616C-page 40
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
3.4.3
RC_RUN MODE
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.
In RC_RUN mode, the CPU and peripherals are
clocked from the internal oscillator block using the
INTOSC multiplexer and 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. This mode works
well for user applications that are not highly timing
sensitive, or do not require high-speed clocks at all
times.
If the IRCF bits 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 system clocks.
If the primary clock source is the internal oscillator
block (either of the INTIO1 or INTIO2 oscillators), there
are no distinguishable 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.
If the IRCF bits are changed from all clear (thus
enabling the INTOSC output), the IOFS bit becomes
set after the INTOSC output becomes stable. Clocks to
the system continue while the INTOSC source
stabilizes in approximately 1 ms.
If the IRCF bits were previously at a non-zero value
before the SLEEP instruction was executed, and the
INTOSC source was already stable, the IOFS bit will
remain set.
This mode is entered by clearing the IDLEN bit, setting
SCS1 (SCS0 is ignored) and executing a SLEEP
instruction. The IRCF bits may select the clock
frequency before the SLEEP instruction is executed.
When the clock source is switched to the INTOSC
multiplexer (see Figure 3-10), the primary oscillator is
shut down and the OSTS bit is cleared.
When a wake event occurs, the system 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 primary clock occurs (see
Figure 3-8). When the clock switch is complete, the
IOFS bit is cleared, the OSTS bit is set and the primary
clock provides the system clock. 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.
The IRCF bits may be modified at any time to immedi-
ately change the system clock speed. Executing a
SLEEPinstruction is not required to select a new clock
frequency from the INTOSC multiplexer.
FIGURE 3-10:
TIMING TRANSITION TO RC_RUN MODE
Q4 Q1 Q2 Q3 Q4 Q1
Q2
Q3
Q4
Q1
Q2
Q3
1
2
3
4
5
6
7
8
INTRC
OSC1
Clock Transition
CPU
Clock
Peripheral
Clock
Program
Counter
PC + 2
PC
PC + 4
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 41
PIC18F2331/2431/4331/4431
3.4.4
EXIT TO IDLE MODE
3.5
Wake From Power-Managed
Modes
An exit from a power-managed Run mode to its corre-
sponding Idle mode is executed by setting the IDLEN
bit and executing a SLEEP instruction. The CPU is
halted at the beginning of the instruction following the
SLEEPinstruction. There are no changes to any of the
clock source status bits (OSTS, IOFS or T1RUN).
While the CPU is halted, the peripherals continue to be
clocked from the previously selected clock source.
An exit from any of the power-managed modes is trig-
gered 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 Sections 3.2 through 3.4).
Note:
If application code is timing sensitive, it
should wait for the OSTS bit to become set
before continuing. Use the interval during
the Low-Power mode exit sequence
(before OSTS is set) to perform timing
insensitive “housekeeping” tasks.
3.4.5
EXIT TO SLEEP MODE
An exit from a power-managed Run mode to Sleep
mode is executed by clearing the IDLEN and
SCS1:SCS0 bits and executing a SLEEP instruction.
The code is no different than the method used to invoke
Sleep mode from the normal operating (full power)
mode.
Device behavior during Low-Power mode exits is
summarized in Table 3-3.
The primary clock and internal oscillator block are dis-
abled. The INTRC will continue to operate if the WDT
is enabled. The Timer1 oscillator will continue to run, if
enabled, in the T1CON register. All clock source status
bits are cleared (OSTS, IOFS and T1RUN).
3.5.1
EXIT BY INTERRUPT
Any of the available interrupt sources can cause the
device to exit a power-managed mode and resume full
power operation. To enable this functionality, an inter-
rupt 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. On all exits from Low-Power mode by interrupt,
code execution branches to the interrupt vector if the
GIE/GIEH bit (INTCON<7>) is set. Otherwise, code
execution continues or resumes without branching
(see Section 9.0 “Interrupts”).
DS39616C-page 42
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 3-3:
ACTIVITY AND EXIT DELAY ON WAKE FROM SLEEP MODE OR ANY IDLE MODE
(BY CLOCK SOURCES)
Activity During Wake from
ClockReady
Status bit
Clock in
Power-Managed
Mode
Primary System Power-Managed
Power-Managed Mode
Clock
Mode Exit Delay
(OSCCON)
Exit by Interrupt
Exit by Reset
LP, XT, HS
HSPLL
EC, RC, INTRC(1)
INTOSC(2)
LP, XT, HS
HSPLL
EC, RC, INTRC(1)
INTOSC(2)
LP, XT, HS
HSPLL
EC, RC, INTRC(1)
INTOSC(2)
LP, XT, HS
HSPLL
CPU and peripherals
clocked by primary
clock and executing
instructions.
Not clocked or
OSTS
Primary System
Clock
(PRI_IDLE mode)
Two-Speed Start-up
5-10 μs(5)
(if enabled).(3)
—
IOFS
OST
OST + 2 ms
5-10 μs(5)
1 ms(4)
CPU and peripherals
clocked by selected
power-managed mode
clock and executing
instructions until
OSTS
T1OSC or
INTRC(1)
—
IOFS
primary clock source
becomes ready.
OST
OSTS
OST + 2 ms
5-10 μs(5)
None
INTOSC(2)
—
IOFS
OST
Not clocked or
OSTS
Two-Speed Start-up (if
enabled) until primary
clock source becomes
OST + 2 ms
5-10 μs(5)
1 ms(4)
Sleep mode
EC, RC, INTRC(1)
INTOSC(2)
—
ready(3)
.
IOFS
Note 1: In this instance, refers specifically to the INTRC clock source.
2: Includes both the INTOSC 8 MHz source and postscaler derived frequencies.
3: Two-Speed Start-up is covered in greater detail in Section 22.3 “Two-Speed Start-up”.
4: Execution continues during the INTOSC stabilization period.
5: Required delay when waking from Sleep and all Idle modes. This delay runs concurrently with any other
required delays (see Section 3.3 “Idle Modes”).
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 43
PIC18F2331/2431/4331/4431
3.5.2
EXIT BY RESET
3.5.4
EXIT WITHOUT AN OSCILLATOR
START-UP DELAY
Normally, the device is held in Reset by the Oscillator
Start-up Timer (OST) until the primary clock (defined in
Configuration Register 1H) becomes ready. At that
time, the OSTS bit is set and the device begins
executing code.
Certain exits from power-managed modes do not
invoke the OST at all. These are:
• PRI_IDLE mode where the primary clock source
is not stopped; and
Code execution can begin before the primary clock
becomes ready. If either the Two-Speed Start-up (see
Section 22.3 “Two-Speed Start-up”) or Fail-Safe
Clock Monitor (see Section 22.4 “Fail-Safe Clock
Monitor”) are enabled in Configuration Register 1H,
the device may begin execution as soon as the Reset
source has cleared. Execution is clocked by the
INTOSC multiplexer driven by the internal oscillator
block. Since the OSCCON register is cleared following
all Resets, the INTRC clock source is selected. A
higher speed clock may be selected by modifying the
IRCF bits in the OSCCON register. 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.
• the primary clock source is not any of the LP, XT,
HS or HSPLL modes.
In these cases, 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 (approximately 10 μs) 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.
3.6
INTOSC Frequency Drift
The factory calibrates the internal oscillator block out-
put (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.
3.5.3
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.
It is possible to adjust the INTOSC frequency by modi-
fying the value in the OSCTUNE register. This has the
side effect that the INTRC clock source frequency is
also affected. However, the features that use the
INTRC source often do not require an exact frequency.
These features include the Fail-Safe Clock Monitor, the
Watchdog Timer and the RC_RUN/RC_IDLE modes
when the INTRC clock source is selected.
If the device is not executing code (all Idle modes and
Sleep mode), the time-out will result in a wake from the
power-managed mode (see Section 3.2 “Sleep
Mode” through Section 3.4 “Run Modes”).
If the device is executing code (all Run modes), the
time-out will result in a WDT Reset (see Section 22.2
“Watchdog Timer (WDT)”).
Being able to adjust the INTOSC requires knowing
when an adjustment is required, in which direction it
should be made, and in some cases, how large a
change is needed. Three examples follow, but other
techniques may be used.
The WDT timer and postscaler are cleared by execut-
ing a SLEEP or CLRWDT instruction, 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
system clock source.
DS39616C-page 44
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
3.6.1
EXAMPLE – EUSART
3.6.3
EXAMPLE – CCP IN CAPTURE MODE
An adjustment may be indicated when the EUSART
begins to generate framing errors, or receives data with
errors while in Asynchronous mode. Framing errors
indicate that the system clock frequency is too high –
try decrementing the value in the OSCTUNE register to
reduce the system clock frequency. Errors in data
may suggest that the system clock speed is too low –
increment OSCTUNE.
A CCP module can use free-running Timer1, clocked
by the internal oscillator block and an external event
with a known period (i.e., AC power frequency). 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.
3.6.2
EXAMPLE – TIMERS
This technique compares system 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 calculated
time, the internal oscillator block is running too fast –
decrement OSCTUNE. If the measured time is much
less than the calculated time, the internal oscillator block
is running too slow – increment OSCTUNE.
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 – decrement OSCTUNE.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 45
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 46
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Most registers are not affected by a WDT wake-up,
since this is viewed as the resumption of normal
4.0
RESET
The PIC18F2331/2431/4331/4431 devices differentiate
between various kinds of Reset:
operation. 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 4-2.
These bits are used in software to determine the nature
of the Reset. See Table 4-3 for a full description of the
Reset states of all registers.
a) Power-on Reset (POR)
b) MCLR Reset during normal operation
c) MCLR Reset during Sleep
d) Watchdog Timer (WDT) Reset (during
execution)
A simplified block diagram of the on-chip Reset circuit
is shown in Figure 4-1.
e) Programmable Brown-out Reset (BOR)
f) RESETInstruction
The enhanced MCU devices have a MCLR noise filter
in the MCLR Reset path. The filter will detect and
ignore small pulses.
g) Stack Full Reset
h) Stack Underflow Reset
The MCLR pin is not driven low by any internal Resets,
including the WDT.
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.
The MCLR input provided by the MCLR pin can be dis-
abled with the MCLRE bit in Configuration Register 3H
(CONFIG3H<7>). See Section 22.1 “Configuration
Bits” for more information.
FIGURE 4-1:
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
RESET
Instruction
Stack
Pointer
Stack Full/Underflow Reset
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
Q
R
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 4-1 for time-out situations.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 47
PIC18F2331/2431/4331/4431
4.1
Power-on Reset (POR)
4.2
Power-up Timer (PWRT)
A Power-on Reset pulse is generated on-chip when
VDD rise is detected. To take advantage of the POR
circuitry, just tie the MCLR pin through a resistor (1k to
10 kΩ) to VDD. This will eliminate external RC compo-
nents 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.
The Power-up Timer (PWRT) of the PIC18F2331/2431/
4331/4431 devices is an 11-bit counter, which uses the
INTRC source as the clock input. This yields a count of
2048 x 32 μs = 65.6 ms. While the PWRT is counting,
the device is held in Reset.
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.
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.
The PWRT is enabled by clearing Configuration bit
PWRTEN.
4.3
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.
Note:
The following decoupling method is
recommended:
1. A 1 μF capacitor should be connected
across AVDD and AVSS.
2. A similar capacitor should be
connected across VDD and VSS.
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.
FIGURE 4-2:
EXTERNAL POWER-ON
RESET CIRCUIT (FOR
SLOW VDD POWER-UP)
4.4
PLL Lock Time-out
With the PLL enabled in its PLL mode, the time-out
sequence following a Power-on Reset is slightly
different from other oscillator modes. A portion of the
Power-up 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.
VDD
VDD
D
R
R1
MCLR
PIC18FXXXX
C
4.5
Brown-out Reset (BOR)
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.
A Configuration bit, BOREN, can disable (if clear/
programmed) or enable (if set) the Brown-out Reset
circuitry. If VDD falls below VBOR (parameter D005A
through D005K) for greater than TBOR (parameter 35),
the brown-out situation will reset the chip. A Reset 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. 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. Enabling
the Brown-out Reset does not automatically enable the
PWRT.
2: R < 40 kΩ is recommended to make
sure that the voltage drop across R does
not violate the device’s electrical specifi-
cation.
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).
DS39616C-page 48
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
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.
4.6
Time-out Sequence
On power-up, the time-out sequence is as follows:
First, after the POR pulse has cleared, PWRT time-out
is invoked (if enabled). Then, the OST is activated. The
total time-out will vary based on oscillator configuration
and the status of the PWRT. For example, in RC mode
with the PWRT disabled, there will be no time-out at all.
Figures 4-3 through 4-7 depict time-out sequences on
power-up.
Table 4-2 shows the Reset conditions for some Special
Function Registers, while Table 4-3 shows the Reset
conditions for all the registers.
TABLE 4-1:
TIME-OUT IN VARIOUS SITUATIONS
(2)
Power-up and Brown-out
Oscillator
Configuration
Exit From
Power-Managed Mode
PWRTEN = 0
PWRTEN = 1
(1)
(2)
(2)
(2)
HSPLL
66 ms + 1024 TOSC + 2 ms
1024 TOSC + 2 ms
1024 TOSC + 2 ms
(1)
HS, XT, LP
EC, ECIO
66 ms + 1024 TOSC
1024 TOSC
1024 TOSC
(1)
66 ms
—
—
—
—
—
—
(1)
RC, RCIO
66 ms
(1)
INTIO1, INTIO2
66 ms
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 4x PLL to lock.
REGISTER 4-1:
RCON REGISTER BITS AND POSITIONS
R/W-0
IPEN
U-0
—
U-0
—
R/W-1
RI
R-1
TO
R-1
PD
R/W-0
POR
R/W-0
BOR
bit 7
Note:
bit 0
Refer to Section 5.14 “RCON Register” for bit definitions.
TABLE 4-2:
STATUS BITS, THEIR SIGNIFICANCE AND THE INITIALIZATION CONDITION FOR
RCON REGISTER
Program
Counter
RCON
Register
Condition
RI TO PD POR BOR STKFUL STKUNF
Power-on Reset
RESETInstruction
Brown-out
0000h
0000h
0000h
0000h
0--1 1100
0--0 uuuu
0--1 11u-
0--u 1uuu
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
MCLR Reset during power-managed
Run modes
MCLR Reset during power-managed Idle
and Sleep modes
0000h
0000h
0--u 10uu
0--u 0uuu
u
u
1
0
0
u
u
u
u
u
u
u
u
u
WDT Time-out during full power or
power-managed Run modes
MCLR Reset during full power execution
Stack Full Reset (STVREN = 1)
u
1
u
u
u
u
1
1
0000h
0000h
0--u uuuu
u
u
u
u
u
Stack Underflow Reset (STVREN = 1)
Stack Underflow Error (not an actual
Reset, STVREN = 0)
u--u uuuu
u--u 00uu
u--u u0uu
u
u
u
u
0
u
u
0
0
u
u
u
u
u
u
WDT time-out during power-managed Idle
or Sleep modes
PC + 2
u
u
u
u
(1)
Interrupt exit from power-managed modes PC + 2
Legend: u= unchanged, x= unknown, - = unimplemented bit, read as ‘0’.
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 (0x000008h or 0x000018h).
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 49
PIC18F2331/2431/4331/4431
TABLE 4-3:
INITIALIZATION CONDITIONS FOR ALL REGISTERS
MCLR Resets
WDT Reset
Power-on Reset,
Brown-out Reset
Wake-up via WDT
or Interrupt
Register
Applicable Devices
RESETInstruction
Stack Resets
TOSU
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
---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)
uuuu uuuu(3)
uuuu uuuu(3)
uu-u uuuu(3)
---u uuuu
uuuu uuuu
PC + 2(2)
--uu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu(1)
uuuu -u-u(1)
uu-u u-uu(1)
N/A
TOSH
TOSL
STKPTR
PCLATU
PCLATH
PCL
TBLPTRU
TBLPTRH
TBLPTRL
TABLAT
PRODH
PRODL
INTCON
INTCON2
INTCON3
INDF0
POSTINC0
N/A
N/A
N/A
POSTDEC0 2331 2431 4331 4431
N/A
N/A
N/A
PREINC0
PLUSW0
FSR0H
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
N/A
N/A
N/A
N/A
N/A
N/A
---- xxxx
xxxx xxxx
xxxx xxxx
N/A
---- uuuu
uuuu uuuu
uuuu uuuu
N/A
---- uuuu
uuuu uuuu
uuuu uuuu
N/A
FSR0L
WREG
INDF1
POSTINC1
N/A
N/A
N/A
POSTDEC1 2331 2431 4331 4431
N/A
N/A
N/A
PREINC1
PLUSW1
2331 2431 4331 4431
2331 2431 4331 4431
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 4-2 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’.
6: Bit 3 of PORTE and LATE are enabled if MCLR functionality is disabled. When not enabled as the PORTE
pin, they are disabled and read as ‘0’. The 28-pin devices have only RE3 on PORTE when MCLR is
disabled.
DS39616C-page 50
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 4-3:
Register
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
MCLR Resets
WDT Reset
Power-on Reset,
Brown-out Reset
Wake-up via WDT
or Interrupt
Applicable Devices
RESETInstruction
Stack Resets
FSR1H
FSR1L
BSR
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
---- 0000
xxxx xxxx
---- 0000
N/A
---- uuuu
uuuu uuuu
---- 0000
N/A
---- uuuu
uuuu uuuu
---- uuuu
N/A
INDF2
POSTINC2
N/A
N/A
N/A
POSTDEC2 2331 2431 4331 4431
N/A
N/A
N/A
PREINC2
PLUSW2
FSR2H
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
N/A
N/A
N/A
N/A
N/A
N/A
---- 0000
xxxx xxxx
---x xxxx
0000 0000
xxxx xxxx
1111 1111
0000 q000
--00 0101
0--- ---0
0--1 11q0
xxxx xxxx
xxxx xxxx
0000 0000
0000 0000
1111 1111
-000 0000
xxxx xxxx
0000 0000
0000 0000
0000 0000
---- uuuu
uuuu uuuu
---u uuuu
0000 0000
uuuu uuuu
1111 1111
0000 q000
--00 0101
0--- ---0
0--q qquu
uuuu uuuu
uuuu uuuu
u0uu uuuu
0000 0000
1111 1111
-000 0000
uuuu uuuu
0000 0000
0000 0000
0000 0000
---- uuuu
uuuu uuuu
---u uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
--uu uuuu
u--- ---u
u--u qquu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
1111 1111
-uuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
FSR2L
STATUS
TMR0H
TMR0L
T0CON
OSCCON
LVDCON
WDTCON
RCON(4)
TMR1H
TMR1L
T1CON
TMR2
PR2
T2CON
SSPBUF
SSPADD
SSPSTAT
SSPCON
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 4-2 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’.
6: Bit 3 of PORTE and LATE are enabled if MCLR functionality is disabled. When not enabled as the PORTE
pin, they are disabled and read as ‘0’. The 28-pin devices have only RE3 on PORTE when MCLR is
disabled.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 51
PIC18F2331/2431/4331/4431
TABLE 4-3:
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
MCLR Resets
Power-on Reset,
Brown-out Reset
WDT Reset
RESETInstruction
Stack Resets
Wake-up via WDT
or Interrupt
Register
Applicable Devices
ADRESH
ADRESL
ADCON0
ADCON1
ADCON2
ADCON3
ADCHS
CCPR1H
CCPR1L
CCP1CON
CCPR2H
CCPR2L
CCP2CON
ANSEL1
ANSEL0
T5CON
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
xxxx xxxx
xxxx xxxx
--00 0000
00-0 0000
0000 0000
00-0 0000
0000 0000
xxxx xxxx
xxxx xxxx
--00 0000
xxxx xxxx
xxxx xxxx
--00 0000
---- ---1
1111 1111
0000 0000
0000 0000
0000 0000
0000 0000
0000 0000
0000 0000
0000 -010
0000 000x
-1-1 0-00
0000 0000
0000 0000
0000 0000
xx-0 x000
---1 1111
---0 0000
---0 0000
uuuu uuuu
uuuu uuuu
--00 0000
00-0 0000
0000 0000
00-0 0000
0000 0000
uuuu uuuu
uuuu uuuu
--00 0000
uuuu uuuu
uuuu uuuu
--00 0000
---- ---1
1111 1111
0000 0000
0000 0000
0000 0000
0000 0000
0000 0000
0000 0000
0000 -010
0000 000x
-1-1 0-00
0000 0000
0000 0000
0000 0000
uu-0 u000
---1 1111
---0 0000
---0 0000
uuuu uuuu
uuuu uuuu
--uu uuuu
uu-u uuuu
uuuu uuuu
uu-u uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
--uu uuuu
uuuu uuuu
uuuu uuuu
--uu uuuu
---- ---u
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu -uuu
uuuu uuuu
-u-u u-uu
uuuu uuuu
uuuu uuuu
0000 0000
uu-0 u000
---u uuuu
---u uuuu
---u uuuu
QEICON
SPBRGH
SPBRG
RCREG
TXREG
TXSTA
RCSTA
BAUDCTL
EEADR
EEDATA
EECON2
EECON1
IPR3
PIE3
PIR3
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 4-2 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’.
6: Bit 3 of PORTE and LATE are enabled if MCLR functionality is disabled. When not enabled as the PORTE
pin, they are disabled and read as ‘0’. The 28-pin devices have only RE3 on PORTE when MCLR is
disabled.
DS39616C-page 52
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 4-3:
Register
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
MCLR Resets
WDT Reset
Power-on Reset,
Brown-out Reset
Wake-up via WDT
or Interrupt
Applicable Devices
RESETInstruction
Stack Resets
IPR2
PIR2
PIE2
IPR1
PIR1
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
1--1 -1-1
0--0 -0-0
0--0 -0-0
-111 1111
-000 0000
-000 0000
0000 0000
-000 0000
--00 0000
---- -111
1111 1111
1111 1111
1111 1111
1111 1111(5)
1111 1111
1111 1111
---- -xxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx(5)
xxxx xxxx
xxxx xxxx
---- xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xx0x 0000(5)
1--1 -1-1
0--0 -0-0
0--0 -0-0
-111 1111
-000 0000
-000 0000
0000 0000
-000 0000
--00 0000
---- -111
1111 1111
1111 1111
1111 1111
1111 1111(5)
1111 1111
1111 1111
---- -uuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu(5)
uuuu uuuu
uuuu uuuu
---- xxxx
uuuu uuuu
uuuu uuuu
uuuu uuuu
uu0u 0000(5)
u--u -u-u
u--u -u-u
u--u -u-u
-uuu uuuu
-uuu uuuu(1)
-uuu uuuu(1)
uuuu uuuu
-uuu uuuu
--uu uuuu
---- -uuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu(5)
uuuu uuuu
uuuu uuuu
---- -uuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu(5)
uuuu uuuu
uuuu uuuu
---- uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu(5)
PIE1
OSCTUNE
TRISE(6)
TRISD
TRISC
TRISB
TRISA(5)
PR5H
PR5L
LATE(6)
LATD
LATC
LATB
LATA(5)
TMR5H
TMR5L
PORTE(6)
PORTD
PORTC
PORTB
PORTA(5)
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 4-2 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’.
6: Bit 3 of PORTE and LATE are enabled if MCLR functionality is disabled. When not enabled as the PORTE
pin, they are disabled and read as ‘0’. The 28-pin devices have only RE3 on PORTE when MCLR is
disabled.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 53
PIC18F2331/2431/4331/4431
TABLE 4-3:
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
MCLR Resets
Power-on Reset,
Brown-out Reset
WDT Reset
RESETInstruction
Stack Resets
Wake-up via WDT
or Interrupt
Register
Applicable Devices
PTCON0
PTCON1
PTMRL
PTMRH
PTPERL
PTPERH
PDC0L
PDC0H
PDC1L
PDC1H
PDC2L
PDC2H
PDC3L
PDC3H
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
0000 0000
00-- ----
0000 0000
---- 0000
1111 1111
---- 1111
0000 0000
--00 0000
0000 0000
--00 0000
0000 0000
--00 0000
0000 0000
--00 0000
0000 0000
---- 0000
-111 0000
0000 0-00
0000 0000
0000 0000
1111 1111
0000 0000
uuuu uuuu
00-- ----
0000 0000
---- 0000
1111 1111
---- 1111
0000 0000
--00 0000
0000 0000
--00 0000
0000 0000
--00 0000
0000 0000
--00 0000
0000 0000
---- 0000
-111 0000
0000 0-00
0000 0000
0000 0000
1111 1111
0000 0000
uuuu uuuu
uu-- ----
uuuu uuuu
---- uuuu
uuuu uuuu
---- uuuu
uuuu uuuu
--uu uuuu
uuuu uuuu
--uu uuuu
uuuu uuuu
--uu uuuu
uuuu uuuu
--uu uuuu
uuuu uuuu
---- uuuu
-uuu uuuu
uuuu u-uu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
SEVTCMPL 2331 2431 4331 4431
SEVTCMPH 2331 2431 4331 4431
PWMCON0 2331 2431 4331 4431
PWMCON1 2331 2431 4331 4431
DTCON
2331 2431 4331 4431
FLTCONFIG 2331 2431 4331 4431
OVDCOND 2331 2431 4331 4431
OVDCONS
2331 2431 4331 4431
CAP1BUFH/ 2331 2431 4331 4431
VELRH
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
CAP1BUFL/ 2331 2431 4331 4431
VELRL
CAP2BUFH/ 2331 2431 4331 4431
POSCNTH
CAP2BUFL/ 2331 2431 4331 4431
POSCNTL
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 4-2 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’.
6: Bit 3 of PORTE and LATE are enabled if MCLR functionality is disabled. When not enabled as the PORTE
pin, they are disabled and read as ‘0’. The 28-pin devices have only RE3 on PORTE when MCLR is
disabled.
DS39616C-page 54
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 4-3:
Register
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
MCLR Resets
WDT Reset
Power-on Reset,
Brown-out Reset
Wake-up via WDT
or Interrupt
Applicable Devices
RESETInstruction
Stack Resets
CAP3BUFH/ 2331 2431 4331 4431
MAXCNTH
xxxx xxxx
xxxx xxxx
uuuu uuuu
uuuu uuuu
uuuu uuuu
CAP3BUFL/ 2331 2431 4331 4431
MAXCNTL
uuuu uuuu
CAP1CON
CAP2CON
CAP3CON
DFLTCON
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
2331 2431 4331 4431
-0-- 0000
-0-- 0000
-0-- 0000
-000 0000
-0-- 0000
-0-- 0000
-0-- 0000
-000 0000
-u-- uuuu
-u-- uuuu
-u-- uuuu
-uuu 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 4-2 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’.
6: Bit 3 of PORTE and LATE are enabled if MCLR functionality is disabled. When not enabled as the PORTE
pin, they are disabled and read as ‘0’. The 28-pin devices have only RE3 on PORTE when MCLR is
disabled.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 55
PIC18F2331/2431/4331/4431
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
DS39616C-page 56
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 4-6:
SLOW RISE TIME (MCLR TIED TO VDD, VDD RISE > TPWRT)
5V
1V
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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 57
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 58
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
5.1
Program Memory Organization
5.0
MEMORY ORGANIZATION
A 21-bit program counter is capable of addressing the
2-Mbyte program memory space. Accessing a location
between the physically implemented memory and the
2-Mbyte address will cause a read of all ‘0’s (a NOP
instruction).
There are three memory types in enhanced MCU
devices. These memory types are:
• Program Memory
• Data RAM
• Data EEPROM
The PIC18F2331/4331 devices each have 8 Kbytes of
Flash memory and can store up to 4,096 single-word
instructions.
Data and program memory use separate busses,
which allows for concurrent access of these types.
Additional detailed information for Flash program mem-
ory and data EEPROM is provided in Section 6.0
“Flash Program Memory” and Section 7.0 “Data
EEPROM Memory”, respectively.
The PIC18F2431/4431 devices each have 16 Kbytes
of Flash memory and can store up to 8,192 single-word
instructions.
The Reset vector address is at 000000h and the
interrupt vector addresses are at 000008h and
000018h.
The program memory maps for PIC18F2331/4331 and
PIC18F2431/4431 devices are shown in Figure 5-1
and Figure 5-2, respectively.
FIGURE 5-1:
PROGRAM MEMORY MAP
AND STACK FOR
FIGURE 5-2:
PROGRAM MEMORY MAP
AND STACK FOR
PIC18F2331/4331
PIC18F2431/4431
PC<20:0>
21
PC<20:0>
21
CALL,RCALL,RETURN
RETFIE,RETLW
CALL,RCALL,RETURN
RETFIE,RETLW
Stack Level 1
Stack Level 1
•
•
•
•
•
•
Stack Level 31
Stack Level 31
000000h
000008h
000018h
Reset Vector LSb
000000h
Reset Vector LSb
High-Priority Interrupt Vector LSb
Low-Priority Interrupt Vector LSb
000008h
000018h
High-Priority Interrupt Vector LSb
Low-Priority Interrupt Vector LSb
On-Chip Flash
Program Memory
On-Chip Flash
Program Memory
001FFFh
002000h
003FFFh
004000h
Unused
Read ‘0’s
Unused
Read ‘0’s
1FFFFFh
1FFFFFh
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 59
PIC18F2331/2431/4331/4431
5.2.2
RETURN STACK POINTER
(STKPTR)
5.2
Return Address Stack
The return address stack allows any combination of up
to 31 program calls and interrupts to occur. The PC
(Program Counter) is pushed onto the stack when a
CALLor RCALLinstruction is executed, or an interrupt
is Acknowledged. The PC value is pulled off the stack
on a RETURN, RETLW or a RETFIE instruction.
PCLATU and PCLATH are not affected by any of the
RETURNor CALLinstructions.
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. At 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.
The stack operates as a 31-word by 21-bit RAM and a
5-bit Stack Pointer, with the Stack Pointer initialized to
00000b after all Resets. There is no RAM associated
with Stack Pointer 00000b. This is only a Reset value.
During a CALLtype instruction, causing a push onto the
stack, the Stack Pointer is first incremented and the
RAM location pointed to by the Stack Pointer is written
with the contents of the PC (already pointing to the
instruction following the CALL). During a RETURNtype
instruction, causing a pop from the stack, the contents
of the RAM location pointed to by the STKPTR are
transferred to the PC and then the Stack Pointer is
decremented.
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.
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 22.1 “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 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 (TOS) Special Function
Registers. Data can also be pushed to, or popped from,
the stack using the Top-of-Stack SFRs. Status bits
indicate if the stack is full, has overflowed or underflowed.
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.
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 set the STKUNF bit, while the Stack
Pointer remains at zero. The STKUNF bit will remain
set until cleared by software or a POR occurs.
5.2.1
TOP-OF-STACK ACCESS
The top of the stack is readable and writable. Three
register locations, TOSU, TOSH and TOSL, hold the
contents of the stack location pointed to by the
STKPTR register (Figure 5-3). 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 and TOSL registers.
These values can be placed on a user-defined software
stack. At return time, the software can replace the
TOSU, TOSH and TOSL and do a return.
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.
The user must disable the global interrupt enable bits
while accessing the stack to prevent inadvertent stack
corruption.
FIGURE 5-3:
RETURN ADDRESS STACK AND ASSOCIATED REGISTERS
Return Address Stack
11111
11110
11101
STKPTR<4:0>
TOSU
00h
TOSH
1Ah
TOSL
34h
00010
00011
001A34h 00010
000D58h 00001
00000
Top-of-Stack
DS39616C-page 60
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 5-1:
STKPTR: STACK POINTER REGISTER
R/C-0
STKFUL(1)
R/C-0
STKUNF(1)
U-0
—
R/W-0
SP4
R/W-0
SP3
R/W-0
SP2
R/W-0
SP1
R/W-0
SP0
bit 7
bit 0
Legend:
C = Clearable-only bit
W = Writable bit
‘1’ = Bit is set
R = Readable bit
-n = Value at POR
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
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.
5.2.3
PUSHAND POPINSTRUCTIONS
5.2.4
STACK FULL/UNDERFLOW RESETS
Since the Top-of-Stack (TOS) is readable and writable,
the ability to push values onto the stack and pull values
off the stack without disturbing normal program execu-
tion is a desirable option. To push the current PC value
onto the stack, a PUSH instruction can be executed.
This will increment the Stack Pointer and load the
current PC value onto the stack. TOSU, TOSH and
TOSL can then be modified to place data or a return
address on the stack.
These Resets are enabled by programming the
STVREN bit in Configuration Register 4L. When the
STVREN bit is cleared, a full or underflow condition will
set the appropriate STKFUL or STKUNF bit, but not
cause a device Reset. When the STVREN bit is set, a
full or underflow condition will set the appropriate
STKFUL or STKUNF bit and then cause a device
Reset. The STKFUL or STKUNF bits are cleared by the
user software or a Power-on Reset.
The ability to pull the TOS value off of the stack and
replace it with the value that was previously pushed
onto the stack, without disturbing normal execution, is
achieved by using the POPinstruction. The POPinstruc-
tion discards the current TOS by decrementing the
Stack Pointer. The previous value pushed onto the
stack then becomes the TOS value.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 61
PIC18F2331/2431/4331/4431
5.3
Fast Register Stack
5.4
PCL, PCLATH and PCLATU
A “fast return” option is available for interrupts. A Fast
Register Stack is provided for the STATUS, WREG and
BSR registers and are only one in depth. The stack is
not readable or writable and is loaded with the current
value of the corresponding register when the processor
vectors for an interrupt. The values in the registers are
then loaded back into the working registers if the
RETFIE, FAST instruction is used to return from the
interrupt.
The Program Counter (PC) specifies the address of the
instruction to fetch for execution. The PC is 21 bits
wide. 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 and is not directly readable
or writable. Updates to the PCH register may be per-
formed through the PCLATH register. The upper byte is
called PCU. This register contains the PC<20:16> bits
and is not directly readable or writable. Updates to the
PCU register may be performed through the PCLATU
register.
All interrupt sources will push values into the Stack
registers. 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 inter-
rupt occurs while servicing a low-priority interrupt, the
Stack register values stored by the low-priority interrupt
will be overwritten. Users must save the key registers
in software during a low-priority interrupt.
The contents of PCLATH and PCLATU will be
transferred to the program counter by any operation
that writes PCL. Similarly, the upper two bytes of the
program counter will be transferred to PCLATH and
PCLATU by an operation that reads PCL. This is useful
for computed offsets to the PC (see Section 5.8.1
“Computed GOTO”).
If interrupt priority is not used, all interrupts may use the
Fast Register Stack for returns from interrupt.
The PC addresses bytes in the program memory. To
prevent the PC from becoming misaligned with word
instructions, the LSB of PCL is fixed to a value of ‘0’.
The PC increments by 2 to address sequential
instructions in the program memory.
If no interrupts 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 CALL label, FAST
instruction must be executed to save the STATUS,
WREG and BSR registers to the Fast Register Stack. A
RETURN, FASTinstruction is then executed to restore
these registers from the Fast Register Stack.
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.
Example 5-1 shows a source code example that uses
the Fast Register Stack during a subroutine call and
return.
EXAMPLE 5-1:
FAST REGISTER STACK
CODE EXAMPLE
CALL SUB1, FAST
;STATUS, WREG, BSR
;SAVED IN FAST REGISTER
;STACK
•
•
SUB1
•
•
RETURN FAST ;RESTORE VALUES SAVED
;IN FAST REGISTER STACK
DS39616C-page 62
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
5.5
Clocking Scheme/Instruction
Cycle
5.6
Instruction Flow/Pipelining
An “Instruction Cycle” consists of four Q cycles (Q1,
Q2, Q3 and Q4). The instruction fetch and execute are
pipelined such that fetch takes one instruction cycle,
while decode and execute takes another instruction
cycle. However, due to the pipelining, 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 5-2).
The clock input (from OSC1) is internally divided by
four to generate four non-overlapping quadrature
clocks, namely Q1, Q2, Q3 and Q4. Internally, the
Program Counter (PC) is incremented every Q1, the
instruction is fetched from the program memory and
latched into the Instruction Register (IR) in Q4. The
instruction is decoded and executed during the
following Q1 through Q4. The clocks and instruction
execution flow are shown in Figure 5-4.
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 5-4:
CLOCK/INSTRUCTION CYCLE
Q2
Q3
Q4
Q2
Q3
Q4
Q2
Q3
Q4
Q1
Q1
Q1
OSC1
Q1
Q2
Q3
Internal
Phase
Clock
Q4
PC
PC + 2
PC + 4
PC
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 5-2:
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)
Fetch SUB_1 Execute SUB_1
5. Instruction @ address 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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 63
PIC18F2331/2431/4331/4431
5.7.1
TWO-WORD INSTRUCTIONS
5.7
Instructions in Program Memory
PIC18F2331/2431/4331/4431 devices have four two-
word instructions: MOVFF,CALL,GOTOand LFSR. The
second word of these instructions has the 4 MSBs set
to ‘1’s and is decoded as a NOPinstruction. The lower
12 bits of the second word contain data to be used by
the instruction. If the first word of the instruction is
executed, the data in the second word is accessed. If
the second word of the instruction is executed by itself
(first word was skipped), it will execute as a NOP. This
action is necessary when the two-word instruction is
preceded by a conditional instruction that results in a
skip operation. A program example that demonstrates
this concept is shown in Example 5-3. Refer to
Section 23.0 “Instruction Set Summary” for further
details of the instruction set.
The program memory is addressed in bytes. Instructions
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). Figure 5-5 shows an example of
how instruction words are stored in the program memory.
To maintain alignment with instruction boundaries, the
PC increments in steps of 2 and the LSB will always read
‘0’ (see Section 5.4 “PCL, PCLATH and PCLATU”).
The CALL and GOTO instructions have the absolute
program memory address embedded into the instruction.
Since instructions are always stored on word boundaries,
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 5-5 shows how the instruction
‘GOTO 000006h’ 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 num-
ber of single-word instructions that the PC will be offset
by. Section 23.0 “Instruction Set Summary” provides
further details of the instruction set.
FIGURE 5-5:
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:
0Fh
EFh
F0h
C1h
F4h
55h
03h
00h
23h
56h
MOVLW
GOTO
055h
000006h
Instruction 3:
MOVFF
123h, 456h
EXAMPLE 5-3:
CASE 1:
TWO-WORD INSTRUCTIONS
Source Code
Object Code
0110 0110 0000 0000 TSTFSZ
REG1
; is RAM location 0?
; No, skip this word
; Execute this word as a NOP
; continue code
1100 0001 0010 0011
1111 0100 0101 0110
0010 0100 0000 0000
MOVFF
REG1, REG2
ADDWF
REG3
CASE 2:
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?
; Yes, execute this word
; 2nd word of instruction
; continue code
MOVFF
REG1, REG2
ADDWF
REG3
DS39616C-page 64
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
5.8
Look-up Tables
5.9
Data Memory Organization
Look-up tables are implemented two ways:
The data memory is implemented as static RAM. Each
register in the data memory has a 12-bit address,
allowing up to 4096 bytes of data memory. Figure 5-6
shows the data memory organization for the
PIC18F2331/2431/4331/4431 devices.
• Computed GOTO
• Table Reads
5.8.1
COMPUTED GOTO
The data memory map is divided into as many as
16 banks that contain 256 bytes each. The lower 4 bits
of the Bank Select Register (BSR<3:0>) select which
bank will be accessed. The upper 4 bits for the BSR are
not implemented.
A computed GOTOis accomplished by adding an offset
to the program counter. An example is shown in
Example 5-4.
A look-up table can be formed with an ADDWF PCL
instruction and a group of RETLW 0xnn instructions.
WREG 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 0xnn
instructions, which returns the value 0xnnto the calling
function.
The data memory contains Special Function Registers
(SFR) and General Purpose Registers (GPR). 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. The SFRs start at the last location of Bank
15 (FFFh) and extend to F60h. Any remaining space
beyond the SFRs in the bank may be implemented as
GPRs. GPRs start at the first location of Bank 0 and
grow upwards. Any read of an unimplemented location
will read as ‘0’s.
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.
The entire data memory may be accessed directly or
indirectly. Direct Addressing mode may require the use
of the BSR register. Indirect Addressing mode requires
the use of a File Select Register (FSRn) and a
corresponding Indirect File Operand (INDFn). Each
FSR holds a 12-bit address value that can be used to
access any location in the data memory map without
banking. See Section 5.12 “Indirect Addressing,
INDF and FSR Registers” for Indirect Addressing
details.
EXAMPLE 5-4:
COMPUTED GOTOUSING
AN OFFSET VALUE
MOVFW
CALL
OFFSET
TABLE
ORG
TABLE
0xnn00
ADDWF
RETLW
RETLW
RETLW
PCL
0xnn
0xnn
0xnn
The instruction set and architecture allow operations
across all banks. This may be accomplished by Indirect
Addressing or by the use of the MOVFFinstruction. The
MOVFF instruction is a two-word/two-cycle instruction
that moves a value from one register to another.
.
.
.
To ensure that commonly used registers (SFRs and
select GPRs) can be accessed in a single cycle,
regardless of the current BSR values, an Access Bank
is implemented. A segment of Bank 0 and a segment of
Bank 15 comprise the Access RAM. Section 5.10
“Access Bank” provides a detailed description of the
Access RAM.
5.8.2
TABLE READS/TABLE WRITES
A better method of storing data in program memory
allows two bytes of data to be stored in each instruction
location.
Look-up table data may be stored two bytes per pro-
gram word by using table reads and writes. The Table
Pointer (TBLPTR) specifies the byte address and the
Table Latch (TABLAT) contains the data that is read
from, or written to, program memory. Data is
transferred to/from program memory, one byte at a
time.
5.9.1
GENERAL PURPOSE REGISTER
FILE
Enhanced MCU devices may have banked memory in
the GPR area. GPRs are not initialized by a Power-on
Reset and are unchanged on all other Resets.
The table read/table write operation is discussed
further in Section 6.1 “Table Reads and Table
Writes”.
Data RAM is available for use as GPR registers by all
instructions. The second half of Bank 15 (F60h to
FFFh) contains SFRs. All other banks of data memory
contain GPRs, starting with Bank 0.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 65
PIC18F2331/2431/4331/4431
FIGURE 5-6:
BSR<3:0>
= 0000
DATA MEMORY MAP FOR PIC18F2331/2431/4331/4431 DEVICES
Data Memory Map
000h
05Fh
060h
0FFh
100h
00h
Access RAM
GPR
Bank 0
Bank 1
Bank 2
FFh
00h
= 0001
= 0010
GPR
GPR
1FFh
200h
FFh
00h
FFh
00h
2FFh
300h
Access Bank
00h
Access RAM Low
5Fh
60h
= 0011
= 1110
Access RAM High
(SFRs)
Bank 3
to
Bank 14
Unused
Read ‘00h’
FFh
When a = 0:
The BSR is ignored and the
Access Bank is used.
The first 96 bytes are
General Purpose RAM
(from Bank 0).
EFFh
F00h
F5Fh
F60h
FFFh
00h
FFh
Unused
SFR
= 1111
The second 160 bytes are
Special Function Registers
(from Bank 15).
Bank 15
When a = 1:
The BSR specifies the bank
used by the instruction.
DS39616C-page 66
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
“core” are described in this section, while those related
to the operation of the peripheral features are
described in the section of that peripheral feature.
5.9.2
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. 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.
The unused SFR locations will be unimplemented and
read as ‘0’s.
The SFRs can be classified into two sets; those asso-
ciated with the “core” function and those related to the
peripheral functions. Those registers related to the
TABLE 5-1:
SPECIAL FUNCTION REGISTER MAP FOR PIC18F2331/2431/4331/4431 DEVICES
Address
Name
Address
Name
Address
Name
Address
Name
Address
Name
FFFh
FFEh
FFDh
TOSU
TOSH
TOSL
FDFh
INDF2
FBFh
FBEh
CCPR1H
CCPR1L
F9Fh
F9Eh
F9Dh
F9Ch
IPR1
PIR1
PIE1
—
F7Fh
F7Eh
F7Dh
F7Ch
F7Bh
F7Ah
F79h
F78h
F77h
F76h
F75h
F74h
F73h
F72h
F71h
F70h
F6Fh
F6Eh
F6Dh
F6Ch
F6Bh
F6Ah
F69h
F68h
F67h
F66h
F65h
F64h
F63h
F62h
F61h
F60h
PTCON0
PTCON1
PTMRL
FDEh POSTINC2
FDDh POSTDEC2
FDCh PREINC2
FBDh CCP1CON
FBCh CCPR2H
FFCh
FFBh
FFAh
FF9h
STKPTR
PCLATU
PCLATH
PCL
PTMRH
FDBh
FDAh
FD9h
FD8h
FD7h
FD6h
FD5h
FD4h
PLUSW2
FSR2H
FSR2L
STATUS
TMR0H
TMR0L
T0CON
—
FBBh
CCPR2L
F9Bh OSCTUNE
PTPERL
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
ADCON3
ADCHS
—
PTPERH
PDC0L
FB9h
FB8h
FB7h
FB6h
FB5h
FB4h
FB3h
FB2h
FB1h
ANSEL1
ANSEL0
T5CON
FF8h TBLPTRU
FF7h TBLPTRH
FF6h TBLPTRL
PDC0H
—
PDC1L
QEICON
—
TRISE
TRISD
TRISC
TRISB
TRISA
PR5H
PR5L
—
PDC1H
FF5h
FF4h
FF3h
FF2h
TABLAT
PRODH
PRODL
INTCON
PDC2L
—
—
—
—
PDC2H
FD3h OSCCON
FD2h LVDCON
FD1h WDTCON
PDC3L
PDC3H
FF1h INTCON2
FF0h INTCON3
SEVTCMPL
SEVTCMPH
PWMCON0
PWMCON1
DTCON
FD0h
FCFh
FCEh
FCDh
FCCh
FCBh
FCAh
FC9h
FC8h
RCON
TMR1H
TMR1L
T1CON
TMR2
FB0h SPBRGH
FEFh
INDF0
FAFh
FAEh
FADh
FACh
FABh
SPBRG
RCREG
TXREG
TXSTA
RCSTA
FEEh POSTINC0
FEDh POSTDEC0
FECh PREINC0
—
LATE
LATD
LATC
LATB
LATA
FLTCONFIG
OVDCOND
OVDCONS
CAP1BUFH
CAP1BUFL
CAP2BUFH
CAP2BUFL
CAP3BUFH
CAP3BUFL
CAP1CON
CAP2CON
CAP3CON
DFLTCON
FEBh
FEAh
FE9h
FE8h
FE7h
PLUSW0
FSR0H
FSR0L
WREG
INDF1
PR2
T2CON
SSPBUF
SSPADD
FAAh BAUDCTL
FA9h
FA8h
FA7h
FA6h
FA5h
FA4h
FA3h
FA2h
FA1h
FA0h
EEADR
EEDATA
EECON2
EECON1
IPR3
TMR5H
TMR5L
—
FC7h SSPSTAT
FE6h POSTINC1
FE5h POSTDEC1
FC6h
FC5h
FC4h
FC3h
FC2h
FC1h
FC0h
SSPCON
—
—
FE4h
FE3h
FE2h
FE1h
FE0h
PREINC1
PLUSW1
FSR1H
FSR1L
BSR
ADRESH
ADRESL
ADCON0
ADCON1
ADCON2
PIR3
PORTE
PORTD
PORTC
PORTB
PORTA
PIE3
IPR2
PIR2
PIE2
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 67
PIC18F2331/2431/4331/4431
TABLE 5-2:
File Name
TOSU
REGISTER FILE SUMMARY (PIC18F2331/2431/4331/4431)
Value on
POR, BOR
Details on
page:
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
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
50, 60
50, 60
50, 60
50, 61
50, 62
50, 62
50, 62
50, 80
50, 80
50, 80
50, 80
50, 91
50, 91
50, 95
50, 96
50, 97
50, 73
50, 73
50, 73
50, 73
50, 73
50, 73
50, 73
50
TOSH
Top-of-Stack High Byte (TOS<15:8>)
Top-of-Stack Low Byte (TOS<7:0>)
TOSL
STKPTR
PCLATU
PCLATH
PCL
STKFUL
—
STKUNF
—
—
bit 21(3)
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(3)
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 PEIE/GIEL
TMR0IE
INTEDG1
—
INT0IE
INTEDG2
INT2IE
RBIE
—
TMR0IF
TMR0IP
—
INT0IF
—
RBIF
RBIP
RBPU
INTEDG0
INT1IP
INT2IP
INT1IE
INT2IF
INT1IF
Uses contents of FSR0 to address data memory – value of FSR0 not changed (not a physical register)
Uses contents of FSR0 to address data memory – value of FSR0 post-incremented (not a physical register)
POSTINC0
N/A
POSTDEC0 Uses contents of FSR0 to address data memory – value of FSR0 post-decremented (not a physical register)
N/A
PREINC0
PLUSW0
FSR0H
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 offset by W (not a physical register)
N/A
N/A
—
—
—
—
Indirect Data Memory Address Pointer 0 High
---- xxxx
xxxx xxxx
xxxx xxxx
N/A
FSR0L
Indirect Data Memory Address Pointer 0 Low Byte
Working Register
WREG
INDF1
Uses contents of FSR1 to address data memory – value of FSR1 not changed (not a physical register)
Uses contents of FSR1 to address data memory – value of FSR1 post-incremented (not a physical register)
50, 73
50, 73
50, 73
50, 73
50, 73
51, 73
51, 73
51, 72
51, 73
51, 73
51, 73
51, 73
51, 73
51, 73
51, 73
51, 75
51, 137
51, 137
51, 135
POSTINC1
N/A
POSTDEC1 Uses contents of FSR1 to address data memory – value of FSR1 post-decremented (not a physical register)
N/A
PREINC1
PLUSW1
FSR1H
FSR1L
Uses contents of FSR1 to address data memory – value of FSR1 pre-incremented (not a physical register)
Uses contents of FSR1 to address data memory – value of FSR1 offset by W (not a physical register)
N/A
N/A
—
—
—
—
Indirect Data Memory Address Pointer 1 High Byte
---- 0000
xxxx xxxx
---- 0000
N/A
Indirect Data Memory Address Pointer 1 Low Byte
BSR
—
—
—
—
Bank Select Register
INDF2
Uses contents of FSR2 to address data memory – value of FSR2 not changed (not a physical register)
Uses contents of FSR2 to address data memory – value of FSR2 post-incremented (not a physical register)
POSTINC2
N/A
POSTDEC2 Uses contents of FSR2 to address data memory – value of FSR2 post-decremented (not a physical register)
N/A
PREINC2
PLUSW2
FSR2H
FSR2L
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 offset by W (not a physical register)
N/A
N/A
—
—
—
—
Indirect Data Memory Address Pointer 2 High Byte
---- 0000
xxxx xxxx
---x xxxx
0000 0000
xxxx xxxx
1111 1111
Indirect Data Memory Address Pointer 2 Low Byte
STATUS
TMR0H
TMR0L
T0CON
—
—
—
N
OV
Z
DC
C
Timer0 Register High Byte
Timer0 Register Low Byte
TMR0ON
T016BIT
T0CS
T0SE
PSA
T0PS2
T0PS1
T0PS0
Legend: x= unknown, u= unchanged, -= unimplemented, q= value depends on condition. Shaded cells are unimplemented.
Note 1: RA6 and associated bits are configured as port pins in RCIO, ECIO and INTIO2 (with port function on RA6) Oscillator modes only and read
‘0’ in all other oscillator modes.
2: RA7 and associated bits are configured as port pins in INTIO2 Oscillator mode only and read ‘0’ in all other modes.
3: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
4: If PBADEN = 0, PORTB<4:0> are configured as digital inputs and read unknown, and if PBADEN = 1, PORTB<4:0> are configured as
analog inputs and read ‘0’ following a Reset.
5: These registers and/or bits are not implemented on the PIC18F2331/2431 devices and read as ‘0’.
6: The RE3 port bit is only available when MCLRE fuse (CONFIG3H<7>) is programmed to ‘0’; otherwise, RE3 reads ‘0’. This bit is read-only.
DS39616C-page 68
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 5-2:
REGISTER FILE SUMMARY (PIC18F2331/2431/4331/4431) (CONTINUED)
Value on
POR, BOR
Details on
page:
File Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
OSCCON
LVDCON
WDTCON
RCON
IDLEN
—
IRCF2
—
IRCF1
IRVST
—
IRCF0
LVDEN
—
OSTS
LVDL3
—
IOFS
LVDL2
—
SCS1
LVDL1
—
SCS0
0000 q000
--00 0101
30, 51
51, 265
51, 281
LVDL0
WDTW
IPEN
—
SWDTEN 0--- ---0
—
—
RI
TO
PD
POR
BOR
0--1 11q0 49, 76, 107
TMR1H
Timer1 Register High Byte
Timer1 Register Low Byte
xxxx xxxx
xxxx xxxx
0000 0000
0000 0000
1111 1111
51, 143
51, 143
51, 139
51, 145
51, 145
51, 145
51, 222
51, 222
51, 214
51, 215
52, 261
52, 261
52, 246
52, 247
52, 248
52. 249
52, 250
52, 153
52, 153
TMR1L
T1CON
RD16
T1RUN
T1CKPS1
T1CKPS0 T1OSCEN
T1SYNC
TMR2ON
TMR1CS
T2CKPS1
TMR1ON
TMR2
Timer2 Register
PR2
Timer2 Period Register
TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0
SSP Receive Buffer/Transmit Register
SSP Address Register in I2C™ Slave mode. SSP Baud Rate Reload Register in I2C Master mode.
T2CON
—
T2CKPS0 -000 0000
SSPBUF
SSPADD
SSPSTAT
SSPCON
ADRESH
ADRESL
ADCON0
ADCON1
ADCON2
ADCON3
ADCHS
CCPR1H
CCPR1L
CCP1CON
xxxx xxxx
0000 0000
0000 0000
0000 0000
xxxx xxxx
xxxx xxxx
--00 0000
00-0 0000
0000 0000
00-0 0000
0000 0000
xxxx xxxx
xxxx xxxx
--00 0000
SMP
CKE
D/A
P
S
R/W
UA
BF
WCOL
SSPOV
SSPEN
CKP
SSPM3
SSPM2
SSPM1
SSPM0
A/D Result Register High Byte
A/D Result Register Low Byte
—
—
ACONV
—
ACSCH
FIFOEN
ACQT1
SSRC4
GBSEL0
ACMOD1
BFEMT
ACQT0
SSRC3
GCSEL1
ACMOD0
BFOVFL
ADCS2
GO/DONE
ADPNT1
ADCS1
ADON
ADPNT0
ADCS0
SSRC0
GASEL0
VCFG1
ADFM
VCFG0
ACQT3
ADRS0
GDSEL0
ACQT2
—
ADRS1
GDSEL1
SSRC2
SSRC1
GBSEL1
GCSEL0
GASEL1
Capture/Compare/PWM Register 1 High Byte
Capture/Compare/PWM Register 1 Low Byte
—
—
DC1B1
DC1B0
CCP1M3
CCP1M2
CCP1M1
CCP1M0
52, 156,
149
CCPR2H
CCPR2L
CCP2CON
ANSEL1
ANSEL0
T5CON
Capture/Compare/PWM Register 2 High Byte
Capture/Compare/PWM Register 2 Low Byte
xxxx xxxx
xxxx xxxx
--00 0000
---- ---1
1111 1111
0000 0000
52, 153
52, 153
52, 156
52, 251
52, 251
52, 147
—
—
—
—
DC2B1
—
DC2B0
—
CCP2M3
—
CCP2M2
—
CCP2M1
—
CCP2M0
ANS8(5)
ANS0
ANS7(5)
ANS6(5)
RESEN(5)
ANS5(5)
ANS4
T5PS1
ANS3
T5PS0
ANS2
ANS1
T5SEN
T5MOD
T5SYNC
TMR5CS
TMR5ON
QEICON
SPBRGH
SPBRG
RCREG
VELM
QERR
UP/DOWN
QEIM2
QEIM1
QEIM0
PDEC1
PDEC0
0000 0000
0000 0000
0000 0000
0000 0000
52, 170
52, 227
52, 227
EUSART Baud Rate Generator Register High Byte
EUSART Baud Rate Generator Register Low Byte
EUSART Receive Register
52, 235,
234
TXREG
EUSART Transmit Register
0000 0000
52, 232,
234
TXSTA
CSRC
SPEN
—
TX9
RX9
TXEN
SREN
—
SYNC
CREN
SCKP
SENDB
ADDEN
BRG16
BRGH
FERR
—
TRMT
OERR
WUE
TX9D
RX9D
0000 0010
0000 000x
-1-1 0-00
52, 224
52, 225
52, 226
RCSTA
BAUDCTL
RCIDL
ABDEN
Legend: x= unknown, u= unchanged, -= unimplemented, q= value depends on condition. Shaded cells are unimplemented.
Note 1: RA6 and associated bits are configured as port pins in RCIO, ECIO and INTIO2 (with port function on RA6) Oscillator modes only and read
‘0’ in all other oscillator modes.
2: RA7 and associated bits are configured as port pins in INTIO2 Oscillator mode only and read ‘0’ in all other modes.
3: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
4: If PBADEN = 0, PORTB<4:0> are configured as digital inputs and read unknown, and if PBADEN = 1, PORTB<4:0> are configured as
analog inputs and read ‘0’ following a Reset.
5: These registers and/or bits are not implemented on the PIC18F2331/2431 devices and read as ‘0’.
6: The RE3 port bit is only available when MCLRE fuse (CONFIG3H<7>) is programmed to ‘0’; otherwise, RE3 reads ‘0’. This bit is read-only.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 69
PIC18F2331/2431/4331/4431
TABLE 5-2:
REGISTER FILE SUMMARY (PIC18F2331/2431/4331/4431) (CONTINUED)
Value on
POR, BOR
Details on
page:
File Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
EEADR
EEDATA
EECON2
EECON1
IPR3
EEPROM Address Register
EEPROM Data Register
0000 0000
0000 0000
52, 87
52, 90
EEPROM Control Register 2 (not a physical register)
0000 0000 52, 78, 87
xx-0 x000 52, 79, 88
EEPGD
—
CFGS
—
—
—
FREE
PTIP
WRERR
IC3DRIP
IC3DRIF
IC3DRIE
—
WREN
IC2QEIP
IC2QEIF
IC2QEIE
LVDIP
WR
IC1IP
IC1IF
IC1IE
—
RD
TMR5IP
TMR5IF
TMR5IE
CCP2IP
CCP2IF
CCP2IE
TMR1IP
TMR1IF
TMR1IE
TUN0
---1 1111
---0 0000
---0 0000
1--1 -1-1
0--0 -0-0
0--0 -0-0
-111 1111
-000 0000
-000 0000
--00 0000
00-0 0000
0000 0000
---- -111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
---- -xxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
---- xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xx0x 0000
0000 0000
00-- ----
0000 0000
---- 0000
1111 1111
---- 1111
52, 106
52, 100
52, 103
53, 105
53, 99
53, 102
53, 104
53, 98
53, 101
27, 53
52
PIR3
—
—
—
PTIF
PIE3
—
—
—
PTIE
IPR2
OSCFIP
OSCFIF
OSCFIE
—
—
—
EEIP
EEIF
EEIE
TXIP
TXIF
PIR2
—
—
—
LVDIF
—
PIE2
—
—
—
LVDIE
—
IPR1
ADIP
ADIF
ADIE
—
RCIP
RCIF
RCIE
TUN5
—
SSPIP
SSPIF
SSPIE
TUN3
SSRC3
GCSEL1
—
CCP1IP
CCP1IF
CCP1IE
TUN2
TMR2IP
TMR2IF
TMR2IE
TUN1
SSRC1
GASEL1
PIR1
—
PIE1
—
TXIE
TUN4
SSRC4
GBSEL0
—
OSCTUNE
ADCON3
ADCHS
TRISE(5)
TRISD(5)
TRISC
TRISB
TRISA
PR5H
—
ADRS1
GDSEL1
—
ADRS0
GDSEL0
—
SSRC2
GCSEL0
PORTE Data Direction Register(5)
SSRC0
GASEL0
GBSEL1
—
52
53, 133
53, 130
53, 125
53, 119
53, 113
52
PORTD Data Direction Register
PORTC Data Direction Register
PORTB Data Direction Register
TRISA7(2)
TRISA6(1) PORTA Data Direction Register
Timer5 Period Register High Byte
Timer5 Period Register Low Byte
PR5L
52
LATE(5)
LATD(5)
LATC
—
—
—
—
—
LATE Data Output Register
53, 133
53, 130
53, 125
53, 119
53, 113
148
LATD Data Output Register
LATC Data Output Register
LATB Data Output Register
LATB
LATA
LATA7(2)
LATA6(1) LATA Data Output Register
TMR5H
TMR5L
PORTE
PORTD(5)
PORTC
PORTB
PORTA
PTCON0
PTCON1
PTMRL
PTMRH
PTPERL
PTPERH
Timer5 Register High Byte
Timer5 Register Low Byte
148
—
RD7
—
RD6
—
RD5
RC5
RB5
—
RD4
RC4
RB4
RE3(6)
RD3
RC3
RB3
RE2(5)
RD2
RC2
RB2
RE1(5)
RD1
RE0(5)
RD0
53, 133
53, 130
53, 125
53, 119
53, 113
54, 186
54, 186
184
RC7
RC6
RC1
RC0
RB7
RB6
RB1
RB0
RA7(2)
PTOPS3
PTEN
RA6(1)
PTOPS2
PTDIR
RA5
RA4
RA3
RA2
RA1
RA0
PTOPS1
—
PTOPS0
—
PTCKPS1 PTCKPS0
PTMOD1
—
PTMOD0
—
—
—
PWM Time Base Register (lower 8 bits)
UNUSED
PWM Time Base Register (upper 4 bits)
184
PWM Time Base Period Register (lower 8 bits)
184
UNUSED
PWM Time Base Period Register (upper 4 bits)
184
Legend: x= unknown, u= unchanged, -= unimplemented, q= value depends on condition. Shaded cells are unimplemented.
Note 1: RA6 and associated bits are configured as port pins in RCIO, ECIO and INTIO2 (with port function on RA6) Oscillator modes only and read
‘0’ in all other oscillator modes.
2: RA7 and associated bits are configured as port pins in INTIO2 Oscillator mode only and read ‘0’ in all other modes.
3: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
4: If PBADEN = 0, PORTB<4:0> are configured as digital inputs and read unknown, and if PBADEN = 1, PORTB<4:0> are configured as
analog inputs and read ‘0’ following a Reset.
5: These registers and/or bits are not implemented on the PIC18F2331/2431 devices and read as ‘0’.
6: The RE3 port bit is only available when MCLRE fuse (CONFIG3H<7>) is programmed to ‘0’; otherwise, RE3 reads ‘0’. This bit is read-only.
DS39616C-page 70
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 5-2:
REGISTER FILE SUMMARY (PIC18F2331/2431/4331/4431) (CONTINUED)
Value on
POR, BOR
Details on
page:
File Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
PDC0L
PWM Duty Cycle #0L Register (lower 8 bits)
UNUSED PWM Duty Cycle #0H Register (upper 6 bits)
PWM Duty Cycle #1L Register (lower 8 bits)
0000 0000
--00 0000
0000 0000
--00 0000
0000 0000
--00 0000
0000 0000
--00 0000
0000 0000
184
184
PDC0H
PDC1L
184
PDC1H
PDC2L
UNUSED
PWM Duty Cycle #1H Register (upper 6 bits)
184
PWM Duty Cycle #2L Register (lower 8 bits)
184
PDC2H
PDC3L(5)
PDC3H(5)
UNUSED
PWM Duty Cycle #2H Register (upper 6 bits)
184
PWM Duty Cycle #3L Register (lower 8 bits)
184
UNUSED
PWM Duty Cycle #3H Register (upper 6 bits)
184
SEVTCMPL PWM Special Event Compare Register (lower 8 bits)
N/A
SEVTCMPH
PWMCON0
PWMCON1
DTCON
UNUSED
PWMEN2 PWMEN1
SEVOPS3 SEVOPS2 SEVOPS1 SEVOPS0
PWM Special Event Compare Register (upper 4 bits) ---- 0000
N/A
—
PWMEN0
PMOD3
SEVTDIR
DT3
PMOD2
—
PMOD1
UDIS
PMOD0
OSYNC
DT0
-111 0000
0000 0-00
0000 0000
0000 0000
1111 1111
0000 0000
xxxx xxxx
54, 187
54, 188
54, 200
54, 209
54, 204
54, 204
54
DTPS1
BRFEN
DTPS0
DT5
DT4
DT2
DT1
FLTCONFIG
OVDCOND
OVDCONS
FLTBS(5) FLTBMOD(5) FLTBEN(5)
FLTCON
POVD3
POUT3
FLTAS
POVD2
POUT2
FLTAMOD
POVD1
POUT1
FLTAEN
POVD0
POUT0
POVD7(5)
POUT7(5)
POVD6(5)
POUT6(5)
POVD5
POUT5
POVD4
POUT4
CAP1BUFH/ Capture 1 Register High Byte/Velocity Register High Byte
VELRH
CAP1BUFL/ Capture 1 Register Low Byte/Velocity Register Low Byte
VELRL
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
54
54
54
55
55
CAP2BUFH/ Capture 2 Register High Byte/QEI Position Counter Register High Byte
POSCNTH
CAP2BUFL/ Capture 2 Register Low Byte/QEI Position Counter Register Low Byte
POSCNTL
CAP3BUFH/ Capture 3 Register High Byte/QEI Max. Count Limit Register High Byte
MAXCNTH
CAP3BUFL/ Capture 3 Register Low Byte/QEI Max. Count Limit Register Low Byte
MAXCNTL
CAP1CON
CAP2CON
CAP3CON
DFLTCON
—
—
—
—
CAP1REN
CAP2REN
CAP3REN
FLT4EN
—
—
—
—
CAP1M3
CAP2M3
CAP3M3
FLT1EN
CAP1M2
CAP2M2
CAP3M2
FLTCK2
CAP1M1
CAP2M1
CAP3M1
FLTCK1
CAP1M0 -0-- 0000
CAP2M0 -0-- 0000
CAP3M0 -0-- 0000
FLTCK0 -000 0000
55, 163
55, 163
55, 163
55, 177
—
—
FLT3EN
FLT2EN
Legend: x= unknown, u= unchanged, -= unimplemented, q= value depends on condition. Shaded cells are unimplemented.
Note 1: RA6 and associated bits are configured as port pins in RCIO, ECIO and INTIO2 (with port function on RA6) Oscillator modes only and read
‘0’ in all other oscillator modes.
2: RA7 and associated bits are configured as port pins in INTIO2 Oscillator mode only and read ‘0’ in all other modes.
3: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
4: If PBADEN = 0, PORTB<4:0> are configured as digital inputs and read unknown, and if PBADEN = 1, PORTB<4:0> are configured as
analog inputs and read ‘0’ following a Reset.
5: These registers and/or bits are not implemented on the PIC18F2331/2431 devices and read as ‘0’.
6: The RE3 port bit is only available when MCLRE fuse (CONFIG3H<7>) is programmed to ‘0’; otherwise, RE3 reads ‘0’. This bit is read-only.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 71
PIC18F2331/2431/4331/4431
5.10
Access Bank
5.11 Bank Select Register (BSR)
The Access Bank is an architectural enhancement
which is very useful for C compiler code optimization.
The techniques used by the C compiler may also be
useful for programs written in assembly.
The need for a large general purpose memory space
dictates a RAM banking scheme. The data memory is
partitioned into as many as sixteen banks. When using
Direct Addressing, the BSR should be configured for
the desired bank.
This data memory region can be used for:
BSR<3:0> holds the upper 4 bits of the 12-bit RAM
address. The BSR<7:4> bits will always read ‘0’s and
writes will have no effect (see Figure 5-7).
• Intermediate computational values
• Local variables of subroutines
• Faster context saving/switching of variables
• Common variables
A
MOVLB instruction has been provided in the
instruction set to assist in selecting banks.
• Faster evaluation/control of SFRs (no banking)
If the currently selected bank is not implemented, any
read will return all ‘0’s and all writes are ignored. The
STATUS register bits will be set/cleared as appropriate
for the instruction performed.
The Access Bank is comprised of the last 128 bytes in
Bank 15 (SFRs) and the first 128 bytes in Bank 0.
These two sections will be referred to as Access RAM
High and Access RAM Low, respectively. Figure 5-6
indicates the Access RAM areas.
Each Bank extends up to FFh (256 bytes). All data
memory is implemented as static RAM.
A bit in the instruction word specifies if the operation is
to occur in the bank specified by the BSR register or in
the Access Bank. This bit is denoted as the ‘a’ bit (for
access bit).
A MOVFFinstruction ignores the BSR, since the 12-bit
addresses are embedded into the instruction word.
Section 5.12 “Indirect Addressing, INDF and FSR
Registers” provides a description of Indirect Address-
ing, which allows linear addressing of the entire RAM
space.
When forced in the Access Bank (a = 0), the last
address in Access RAM Low is followed by the first
address in Access RAM High. Access RAM High maps
the Special Function Registers, so these registers can
be accessed without any software overhead. This is
useful for testing status flags and modifying control bits.
FIGURE 5-7:
DIRECT ADDRESSING
Direct Addressing
(3)
From Opcode
BSR<7:4>
BSR<3:0>
7
0
0
0
0
0
(2)
(3)
Bank Select
Location Select
00h
000h
01h
100h
0Eh
E00h
0Fh
F00h
Data
Memory(1)
0FFh
1FFh
EFFh
FFFh
Bank 0
Bank 1
Bank 14 Bank 15
Note 1: For register file map detail, see Table 5-1.
2: The access 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.
3: The MOVFFinstruction embeds the entire 12-bit address in the instruction.
DS39616C-page 72
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
If INDF0, INDF1 or INDF2 are read indirectly via a
5.12 Indirect Addressing, INDF and
FSRn, all ‘0’s are read (Zero bit is set). Similarly, if
INDF0, INDF1 or INDF2 are written to indirectly, the
operation will be equivalent to a NOPinstruction and the
Status bits are not affected.
FSR Registers
Indirect Addressing is a mode of addressing data mem-
ory, where the data memory address in the instruction
is not fixed. An FSR register is used as a pointer to the
data memory location that is to be read or written. Since
this pointer is in RAM, the contents can be modified by
the program. This can be useful for data tables in the
data memory and for software stacks. Figure 5-8
shows how the fetched instruction is modified prior to
being executed.
5.12.1
INDIRECT ADDRESSING
OPERATION
Each FSRn register has an INDFn register associated
with it, plus four additional register addresses. Perform-
ing an operation using one of these five registers
determines how the FSRn will be modified during
Indirect Addressing.
Indirect Addressing is possible by using one of the
INDFn registers. Any instruction using the INDFn reg-
ister actually accesses the register pointed to by the
File Select Register, FSRn. Reading the INDFn register
itself, indirectly (FSRn = 0), will read 00h. Writing to the
INDFn register, indirectly, results in a no operation. The
FSRn register contains a 12-bit address, which is
shown in Figure 5-9.
When data access is performed using one of the five
INDFn locations, the address selected will configure
the FSRn register to:
• Do nothing to FSRn after an indirect access (no
change) – INDFn
• Auto-decrement FSRn after an indirect access
(post-decrement) – POSTDECn
The INDFn register is not a physical register. Address-
ing INDFn actually addresses the register whose
address is contained in the FSRn register (FSRn is a
pointer). This is Indirect Addressing.
• Auto-increment FSRn after an indirect access
(post-increment) – POSTINCn
• Auto-increment FSRn before an indirect access
(pre-increment) – PREINCn
Example 5-5 shows a simple use of Indirect Address-
ing to clear the RAM in Bank 1 (locations 100h-1FFh)
in a minimum number of instructions.
• Use the value in the WREG register as an offset
to FSRn. Do not modify the value of the WREG or
the FSRn register after an indirect access (no
change) – PLUSWn
EXAMPLE 5-5:
HOW TO CLEAR RAM
(BANK 1) USING
When using the auto-increment or auto-decrement
features, the effect on the FSRn is not reflected in the
STATUS register. For example, if Indirect Addressing
causes the FSRn to equal ‘0’, the Z bit will not be set.
INDIRECT ADDRESSING
LFSR FSR0, 0x100
CLRF POSTINC0
;
NEXT
; Clear INDF
; register then
; inc pointer
; All done with
; Bank1?
Auto-incrementing or auto-decrementing
a FSRn
affects all 12 bits. That is, when FSRnL overflows from
an increment, FSRnH will be incremented
automatically.
BTFSS FSR0H, 1
GOTO NEXT
; NO, clear next
; YES, continue
CONTINUE
Adding these features allows the FSRn to be used as a
Stack Pointer in addition to its uses for table operations
in data memory.
There are three Indirect Addressing registers. To
address the entire data memory space (4096 bytes),
these registers are 12 bits wide. To store the 12 bits of
addressing information, two 8-bit registers are
required:
Each FSRn has an address associated with it that
performs an indexed indirect access. When a data
access to this INDFn location (PLUSWn) occurs, the
FSRn is configured to add the signed value in the
WREG register and the value in FSRn to form the
address before an indirect access. The FSRn value is
not changed. The WREG offset range is -128 to +127.
1. FSR0: composed of FSR0H:FSR0L.
2. FSR1: composed of FSR1H:FSR1L.
3. FSR2: composed of FSR2H:FSR2L.
If an FSRn register contains a value that points to one
of the INDFn, an indirect read will read 00h (Zero bit is
set), while an indirect write will be equivalent to a NOP
(Status bits are not affected).
In addition, there are registers, INDF0, INDF1 and
INDF2, which are not physically implemented. Reading
or writing to these registers activates Indirect Address-
ing, with the value in the corresponding FSR register
being the address of the data. If an instruction writes a
value to INDF0, the value will be written to the address
pointed to by FSR0H:FSR0L. A read from INDF1 reads
the data from the address pointed to by
FSR1H:FSR1L. INDFn can be used in code anywhere
an operand can be used.
If an Indirect Addressing write is performed when the
target address is an FSRnH or FSRnL register, the
data is written to the FSRn register, but no pre- or
post-increment/decrement is performed.
© 2007 Microchip Technology Inc.
Preliminary
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FIGURE 5-8:
INDIRECT ADDRESSING OPERATION
0h
RAM
Instruction
Executed
Opcode
Address
12
FFFh
File Address = access of an Indirect Addressing register
BSR<3:0>
12
8
12
Instruction
Fetched
4
Opcode
File
FSRn
FIGURE 5-9:
INDIRECT ADDRESSING
Indirect Addressing
FSRnH:FSRnL
3
0
7
0
0
11
Location Select
0000h
Data
Memory(1)
0FFFh
Note 1: For register file map detail, see Table 5-1.
DS39616C-page 74
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For example, CLRF STATUSwill clear the upper three
bits and set the Z bit. This leaves the STATUS register
5.13 STATUS Register
The STATUS register, shown in Register 5-2, contains
the arithmetic status of the ALU. The STATUS register
can be the operand for any instruction, as with any
other register. If the STATUS register is the destination
for an instruction that affects the Z, DC, C, OV or N bits,
then the write to these five bits is disabled. These bits
are set or cleared according to the device logic. There-
fore, the result of an instruction with the STATUS
register as destination may be different than intended.
as 000u u1uu(where u= unchanged).
It is recommended, therefore, 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. For other instructions not affecting any Status
bits, see Table 23-2.
Note:
The C and DC bits operate as a borrow
and digit borrow bit respectively, in
subtraction.
REGISTER 5-2:
STATUS REGISTER
U-0
—
U-0
U-0
—
R/W-x
N
R/W-x
OV
R/W-x
Z
R/W-x
DC(1)
R/W-x
C(2)
—
bit 7
bit 0
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
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) 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(1)
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
bit 0
C: Carry/borrow bit(2)
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 1: 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.
2: 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.
© 2007 Microchip Technology Inc.
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5.14 RCON Register
Note 1: If the BOREN Configuration bit is set
(Brown-out Reset enabled), the BOR bit
is ‘1’ on a Power-on Reset. After a Brown-
out Reset has occurred, the BOR bit will
be cleared and must be set by firmware to
indicate the occurrence of the next
Brown-out Reset.
The Reset Control (RCON) register contains flag bits
that allow differentiation between the sources of a
device Reset. These flags include the TO, PD, POR,
BOR and RI bits. This register is readable and writable.
2: 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.
REGISTER 5-3:
RCON: RESET CONTROL REGISTER
R/W-0
IPEN
U-0
—
U-0
—
R/W-1
RI
R-1
TO
R-1
PD
R/W-0
POR
R/W-0
BOR
bit 7
bit 0
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
bit 7
IPEN: Interrupt Priority Enable bit
1= Enable priority levels on interrupts
0= Disable priority levels on interrupts (PIC16CXXX Compatibility mode)
bit 6-5
bit 4
Unimplemented: Read as ‘0’
RI: RESETInstruction Flag bit
1= The RESETinstruction was not executed (set by firmware only)
0= The RESET instruction 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
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)
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The program memory space is 16 bits wide, while the
6.0
FLASH PROGRAM MEMORY
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).
The Flash program memory is readable, writable and
erasable during normal operation over the entire VDD
range.
Table read operations retrieve data from program
memory and place it into TABLAT in the data RAM
space. Figure 6-1 shows the operation of a table read
with program memory and data RAM.
A read from program memory is executed on one byte
at a time. A write to program memory is executed on
blocks of 8 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.
Table write operations store data from TABLAT in 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.
While writing or erasing program memory, instruction
fetches cease 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 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,
(TBLPTRL<0> = 0).
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.
6.1
Table Reads and Table Writes
The EEPROM on-chip timer controls the write and
erase times. The write and erase voltages are gener-
ated by an on-chip charge pump rated to operate over
the voltage range of the device for byte or word
operations.
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:
• Table Read (TBLRD)
• Table Write (TBLWT)
FIGURE 6-1:
TABLE READ OPERATION
Instruction: TBLRD*
(1)
Program Memory
Table Pointer
Table Latch (8-bit)
TABLAT
TBLPTRU TBLPTRH TBLPTRL
Program Memory
(TBLPTR)
Note 1: Table Pointer points to a byte in program memory.
© 2007 Microchip Technology Inc.
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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 eight holding registers, the address of which is determined by
TBLPTRL<2:0>. The process for physically writing data to the program memory array is discussed in
Section 6.5 “Writing to Flash Program Memory”.
The WREN bit enables and disables erase and write
operations. When set, erase and write operations are
allowed. When clear, erase and write operations are
disabled – the WR bit cannot be set while the WREN bit
is clear. This process helps to prevent accidental writes
to memory due to errant (unexpected) code execution.
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
Firmware should keep the WREN bit clear at all times,
except when starting erase or write operations. Once
firmware has set the WR bit, the WREN bit may be
cleared. Clearing the WREN bit will not affect the
operation in progress.
6.2.1
EECON1 AND EECON2 REGISTERS
EECON1 is the control register for memory accesses.
The WRERR bit is set when a write operation is inter-
rupted by a Reset. In these situations, the user can
check the WRERR bit and rewrite the location. It will be
necessary to reload the data and address registers
(EEDATA and EEADR) as these registers have cleared
as a result of the Reset.
EECON2 is not a physical register. Reading EECON2
will read all ‘0’s. The EECON2 register is used
exclusively in the memory write and erase sequences.
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.
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.
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.
The RD bit cannot be set when accessing program
memory (EEPGD = 1). Program memory is read using
table read instructions. See Section 6.3 “Reading the
Flash Program Memory” regarding table reads.
The FREE bit controls program memory erase opera-
tions. When the FREE bit is set, the erase operation is
initiated on the next WR command. When FREE is
clear, only writes are enabled.
Note:
Interrupt flag bit, EEIF in the PIR2 register,
is set when the write is complete. It must
be cleared in software.
DS39616C-page 78
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REGISTER 6-1:
EECON1: FLASH PROGRAM/DATA EEPROM CONTROL REGISTER 1
R/W-x
EEPGD
bit 7
R/W-x
CFGS
U-0
—
R/W-0
FREE
R/W-x
WRERR(1)
R/W-0
WREN
R/S-0
WR
R/S-0
RD
bit 0
Legend:
S = Settable only bit
W = Writable bit
‘1’ = Bit is set
R = Readable bit
-n = Value at POR
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
bit 7
bit 6
EEPGD: Flash Program or Data EEPROM Memory Select bit
1= Access program Flash memory
0= Access data EEPROM memory
CFGS: Flash Program/Data EEPROM or Configuration Select bit
1= Access Configuration registers
0= Access program Flash 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 – TBLPTR<5:0> are ignored)
0= Perform write only
bit 3
bit 2
bit 1
WRERR: EEPROM Error Flag bit(1)
1= A write operation is prematurely terminated (any Reset during self-timed programming)
0= The write operation completed normally
WREN: Write Enable bit
1= Allows erase or write cycles
0= Inhibits erase or write cycles
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 completed
bit 0
RD: Read Control bit
1= Initiates a memory read
(Read takes one cycle. RD is cleared in hardware. The RD bit can only be set (not cleared) in soft-
ware. RD bit cannot be set when EEPGD = 1.)
0= Read completed
Note 1: When a WRERR occurs, the EEPGD and CFGS bits are not cleared. This allows tracing of the error
condition.
© 2007 Microchip Technology Inc.
Preliminary
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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 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 TBLRD is executed, all 22 bits of the Table
Pointer determine which byte is read from program or
configuration memory into TABLAT.
6.2.3
TBLPTR – TABLE POINTER
REGISTER
When a TBLWTis executed, the three LSbs of the Table
Pointer (TBLPTR<2:0>) determine which of the eight
program memory holding registers is written to. When
the timed write to program memory (long write) begins,
the 19 MSbs of the Table Pointer, TBLPTR
(TBLPTR<21:3>), will determine which program
memory block of 8 bytes is written to (TBLPTR<2:0>
are ignored). For more detail, see Section 6.5
“Writing to Flash Program Memory”.
The Table Pointer (TBLPTR) 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. Setting 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 (TBLPTR<21:6>) point to
the 64-byte block that will be erased. The Least
Significant bits (TBLPTR<5:0>) are ignored.
The TBLPTR is used by the TBLRDand TBLWTinstruc-
tions. 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 TBLRDAND TBLWTINSTRUCTIONS
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
ERASE – TBLPTR<21:6>
LONG WRITE – TBLPTR<21:3>
READ or WRITE – TBLPTR<21:0>
DS39616C-page 80
Preliminary
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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
6.3
Reading the Flash Program
Memory
The TBLRD instruction is used to retrieve data from
program memory and place it into data RAM. Table
reads from program memory are performed one byte at
a time.
shows the interface between the internal program
memory and the TABLAT.
TBLPTR points to a byte address in program space.
Executing a TBLRDinstruction places the byte pointed
to into TABLAT. In addition, TBLPTR can be modified
automatically for the next table read operation.
FIGURE 6-4:
READS FROM FLASH PROGRAM MEMORY
Program Memory
Odd (High) Byte
Even (Low) Byte
TBLPTR
TBLPTR
LSB = 0
LSB = 1
Instruction Register
(IR)
TABLAT
Read Register
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*+
MOVFW
; read into TABLAT and increment TBLPTR
; get data
TABLAT
MOVWF
WORD_EVEN
TBLRD*+
MOVFW
; read into TABLAT and increment TBLPTR
; get data
TABLAT
MOVWF
WORD_ODD
© 2007 Microchip Technology Inc.
Preliminary
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PIC18F2331/2431/4331/4431
6.4.1
FLASH PROGRAM MEMORY
ERASE SEQUENCE
6.4
Erasing Flash Program Memory
The minimum erase block size is 32 words or 64 bytes
under firmware control. Only through the use of an
external programmer, or through ICSP control can
larger blocks of program memory be bulk erased. Word
erase in Flash memory is not supported.
The sequence of events for erasing a block of internal
program memory location is:
1. Load Table Pointer 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;
The EECON1 register commands the erase operation.
The EEPGD bit must be set to point to the Flash pro-
gram memory. The CFGS bit must be clear to access
program Flash and data EEPROM memory. The
WREN bit must be set to enable write operations. The
FREE bit is set to select an erase operation. The WR
bit is set as part of the required instruction sequence
(as shown in Example 6-2), and starts the actual erase
operation. It is not necessary to load the TABLAT
register with any data, as it is ignored.
- set WREN bit to enable writes;
- set FREE bit to enable the erase.
3. Disable interrupts.
4. Write 55h to EECON2.
5. Write 0AAh to EECON2.
6. Set the WR bit. This will begin the row erase
cycle.
7. The CPU will stall for duration of the erase
(about 2 ms using internal timer).
For protection, the write initiate sequence using
EECON2 must be used.
8. Execute a NOP.
9. Re-enable interrupts.
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.
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
BSF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
EECON1, EEPGD
EECON1, WREN
EECON1, FREE
INTCON, GIE
55h
EECON2
0AAh
EECON2
EECON2, WR
; point to Flash program memory
; enable write to memory
; enable Row Erase operation
; disable interrupts
; write 55H
Required
Sequence
; write 0AAH
; start erase (CPU stall)
NOP
BSF
INTCON, GIE
; re-enable interrupts
DS39616C-page 82
Preliminary
© 2007 Microchip Technology Inc.
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Since the Table Latch (TABLAT) is only a single byte,
6.5
Writing to Flash Program Memory
the TBLWT instruction has to be executed 8 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
8 registers, the EECON1 register must be written to, to
start the programming operation with a long write.
The programming block size is 4 words or 8 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 8 holding registers used by the table writes for
programming.
The long write is necessary for programming the
internal Flash. Instruction execution is halted while in a
long write cycle. The long write will be terminated by
the internal programming timer.
FIGURE 6-5:
TABLE WRITES TO FLASH PROGRAM MEMORY
TABLAT
Write Register
8
8
8
8
TBLPTR = xxxxx0
TBLPTR = xxxxx2
TBLPTR = xxxxx7
Holding Register
TBLPTR = xxxxx1
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.
3. Load Table Pointer with address being erased.
13. Execute a NOP.
14. Re-enable interrupts.
4. Do the row erase procedure (see Section 6.4.1
“Flash Program Memory Erase Sequence”).
15. Repeat steps 6-14 seven times, to write 64
bytes.
5. Load Table Pointer with address of first byte
being written.
16. Verify the memory (table read).
6. Write the first 8 bytes into the holding registers
with auto-increment.
This procedure will require about 18 ms to update one
row of 64 bytes of memory. An example of the required
code is given in Example 6-3.
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 bit to enable byte writes.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 83
PIC18F2331/2431/4331/4431
EXAMPLE 6-3:
WRITING TO FLASH PROGRAM MEMORY
MOVLW
D'64
; number of bytes in erase block
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
COUNTER
BUFFER_ADDR_HIGH
FSR0H
BUFFER_ADDR_LOW
FSR0L
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
; point to buffer
; Load TBLPTR with the base
; address of the memory block
; 6 LSB = 0
READ_BLOCK
TBLRD*+
MOVFW
; read into TABLAT, and inc
; get data
TABLAT
MOVWF
DECFSZ COUNTER
POSTINC0
; store data and increment FSR0
; done?
GOTO
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 and increment FSR0
; update buffer word
ERASE_BLOCK
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
BCF
BSF
BSF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
EECON1, CFGS
EECON1, EEPGD
EECON1, WREN
EECON1, FREE
INTCON, GIE
55h
; load TBLPTR with the base
; address of the memory block
; 6 LSB = 0
; point to PROG/EEPROM memory
; point to Flash program memory
; enable write to memory
; enable Row Erase operation
; disable interrupts
; Required sequence
; write 55H
EECON2
0AAh
EECON2
EECON1, WR
; write 0AAH
; start erase (CPU stall)
NOP
BSF
INTCON, GIE
; re-enable interrupts
WRITE_BUFFER_BACK
MOVLW
8
; number of write buffer groups of 8 bytes
; point to buffer
MOVWF
MOVLW
MOVWF
COUNTER_HI
BUFFER_ADDR_HIGH
FSR0H
MOVLW
MOVWF
BUFFER_ADDR_LOW
FSR0L
PROGRAM_LOOP
MOVLW
8
; number of bytes in holding register
MOVWF
COUNTER
WRITE_WORD_TO_HREGS
MOVFW
POSTINC0
TABLAT
; get low byte of buffer data and increment FSR0
; present data to table latch
; short write
MOVWF
TBLWT+*
; to internal TBLWT holding register, increment
; TBLPTR
DECFSZ COUNTER
; loop until buffers are full
GOTO
WRITE_WORD_TO_HREGS
DS39616C-page 84
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
EXAMPLE 6-3:
WRITING TO FLASH PROGRAM MEMORY (CONTINUED)
PROGRAM_MEMORY
BCF
INTCON, GIE
55h
EECON2
0AAh
EECON2
; disable interrupts
; required sequence
; write 55H
MOVLW
MOVWF
MOVLW
MOVWF
BSF
; write 0AAH
; start program (CPU stall)
EECON1, WR
NOP
BSF
INTCON, GIE
; re-enable interrupts
; loop until done
DECFSZ COUNTER_HI
GOTO
BCF
PROGRAM_LOOP
EECON1, WREN
; disable write to memory
reprogrammed if needed. The WRERR bit is set when
6.5.2
WRITE VERIFY
a write operation is interrupted by a MCLR Reset, or a
WDT Time-out Reset during normal operation. In these
situations, users can check the WRERR bit and rewrite
the location.
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.
6.6
Flash Program Operation During
Code Protection
6.5.3
UNEXPECTED TERMINATION OF
WRITE OPERATION
See Section 22.5 “Program Verification and Code
Protection” for details on code protection of Flash
program memory.
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
TABLE 6-2:
REGISTERS ASSOCIATED WITH PROGRAM FLASH MEMORY
Value on
Value on:
POR, BOR
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
all other
Resets
(1)
TBLPTRU
—
—
bit 21
Program Memory Table Pointer Upper Byte (TBLPTR<20:16>) --00 0000 --00 0000
TBPLTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>)
TBLPTRL Program Memory Table Pointer Low Byte (TBLPTR<7:0>)
TABLAT Program Memory Table Latch
0000 0000 0000 0000
0000 0000 0000 0000
0000 0000 0000 0000
0000 000x 0000 000u
0000 0000 0000 0000
xx-0 x000 uu-0 u000
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE
RBIE
TMR0IF
INT0IF
RBIF
RD
EECON2 EEPROM Control Register 2 (not a physical register)
EECON1 EEPGD
CFGS
—
—
—
—
—
FREE
EEIP
EEIF
EEIE
WRERR
WREN
LVDIP
LVDIF
LVDIE
WR
—
IPR2
OSCFIP
OSCFIF
OSCFIE
—
—
—
CCP2IP 1--1 -1-1 1--1 -1-1
CCP2IF 0--0 -0-0 0--0 -0-0
CCP2IE 0--0 -0-0 0--0 -0-0
PIR2
—
—
PIE2
—
—
Legend:
x= unknown, u= unchanged, -= unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 85
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 86
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Control bit, EEPGD, determines if the access will be to
program or data EEPROM memory. When clear, oper-
ations will access the data EEPROM memory. When
set, program memory is accessed.
7.0
DATA EEPROM MEMORY
The data EEPROM is readable and writable during nor-
mal operation over the entire VDD range. The data
memory is not directly mapped in the register file
space. Instead, it is indirectly addressed through the
Special Function Registers (SFR).
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.
There are four SFRs used to read and write the
program and data EEPROM memory. These registers
are:
• EECON1
• EECON2
• EEDATA
• EEADR
The WREN bit enables and disables erase and write
operations. When set, erase and write operations are
allowed. When clear, erase and write operations are
disabled; the WR bit cannot be set while the WREN bit
is clear. This mechanism helps to prevent accidental
writes to memory due to errant (unexpected) code
execution.
The EEPROM data memory allows byte read and write.
When interfacing to the data memory block, EEDATA
holds the 8-bit data for read/write and EEADR holds the
address of the EEPROM location being accessed.
These devices have 256 bytes of data EEPROM with
an address range from 00h to FFh.
Firmware should keep the WREN bit clear at all times,
except when starting erase or write operations. Once
firmware has set the WR bit, the WREN bit may be
cleared. Clearing the WREN bit will not affect the
operation in progress.
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. The write time will vary with voltage and
temperature, as well as from chip-to-chip. Please
refer to parameter D122 (Table 25-1 in Section 25.0
“Electrical Characteristics”) for exact limits.
The WRERR bit is set when a write operation is
interrupted by a Reset. In these situations, the user can
check the WRERR bit and rewrite the location. It is
necessary to reload the data and address registers
(EEDATA and EEADR), as these registers have
cleared as a result of the Reset.
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
The address register can address 256 bytes of data
EEPROM.
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
EECON1 is the control register for memory accesses.
Note:
Interrupt flag bit, EEIF in the PIR2 register,
is set when write is complete. It must be
cleared in software.
EECON2 is not a physical register. Reading EECON2
will read all ‘0’s. The EECON2 register is used
exclusively in the memory write and erase sequences.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 87
PIC18F2331/2431/4331/4431
REGISTER 7-1:
EECON1: FLASH PROGRAM/DATA EEPROM CONTROL REGISTER 1
R/W-x
EEPGD
bit 7
R/W-x
CFGS
U-0
—
R/W-0
FREE
R/W-x
WRERR(1)
R/W-0
WREN
R/S-0
WR
R/S-0
RD
bit 0
Legend:
S = Settable only bit
W = Writable bit
‘1’ = Bit is set
R = Readable bit
-n = Value at POR
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
bit 7
bit 6
EEPGD: Flash Program or Data EEPROM Memory Select bit
1= Access program Flash memory
0= Access data EEPROM memory
CFGS: Flash Program/Data EEPROM or Configuration Select bit
1= Access Configuration registers
0= Access program Flash 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: EEPROM Error Flag bit(1)
1= A write operation is prematurely terminated (MCLR or WDT Reset during self-timed erase or
program operation)
0= The write operation completed normally
bit 2
bit 1
WREN: Erase/Write Enable bit
1= Allows erase/write cycles
0= Inhibits erase/write cycles
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 completed
bit 0
RD: Read Control bit
1= Initiates a memory 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 = 1.)
0= Read completed
Note 1: When a WRERR occurs, the EEPGD and FREE bits are not cleared. This allows tracing of the error
condition.
DS39616C-page 88
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
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
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 for 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).
set. The WREN bit must be set on a previous instruc-
tion. Both WR and WREN cannot be set with the same
instruction.
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.
7.5
Write Verify
7.4
Writing to the Data EEPROM
Memory
Depending on the application, good programming
practice may dictate that the value written to the mem-
ory should be verified against the original value. This
should be used in applications where excessive writes
can stress bits near the specification limit.
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.
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.
7.6
Protection Against Spurious Write
There are conditions when the device may not want to
write to the data EEPROM memory. To protect against
spurious EEPROM writes, various mechanisms have
been built-in. On power-up, the WREN bit is cleared.
Also, the Power-up Timer (72 ms duration) prevents
EEPROM write.
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-
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.
The write initiate sequence and the WREN bit together
help prevent an accidental write during brown-out,
power glitch, or software malfunction.
EXAMPLE 7-1:
DATA EEPROM READ
MOVLW
MOVWF
BCF
BSF
MOVF
DATA_EE_ADDR
EEADR
EECON1, EEPGD
EECON1, RD
EEDATA, W
;
; Data Memory Address to read
; Point to DATA memory
; EEPROM Read
; W = EEDATA
EXAMPLE 7-2:
DATA EEPROM WRITE
MOVLW
DATA_EE_ADDR
EEADR
DATA_EE_DATA
EEDATA
EECON1, EEPGD
EECON1, WREN
INTCON, GIE
55h
EECON2
0AAh
EECON2
EECON1, WR
INTCON, GIE
;
MOVWF
MOVLW
MOVWF
BCF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
; Data Memory Address to write
;
; Data Memory Value to write
; Point to DATA memory
; Enable writes
; Disable Interrupts
;
; Write 55h
;
; Write 0AAh
; Set WR bit to begin write
; Enable Interrupts
Required
Sequence
BSF
SLEEP
BCF
; Wait for interrupt to signal write complete
; Disable writes
EECON1, WREN
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 89
PIC18F2331/2431/4331/4431
7.7
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 opera-
tions are disabled if either of these mechanisms are
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 or D124A.
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 22.0
“Special Features of the CPU” for additional
information.
A simple data EEPROM refresh routine is shown in
Example 7-3.
Note:
If data EEPROM is only used to store con-
stants and/or data that changes rarely, an
array refresh is likely not required. See
specification D124 or D124A.
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
TABLE 7-1:
REGISTERS ASSOCIATED WITH DATA EEPROM MEMORY
Value on
all other
Resets
Value on:
POR, BOR
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
EEADR
EEDATA
GIE/GIEH PEIE/GIEL TMR0IE INT0IE
EEPROM Address Register
RBIE
TMR0IF
INT0IF
RBIF
0000 000x 0000 000u
0000 0000 0000 0000
0000 0000 0000 0000
0000 0000 0000 0000
xx-0 x000 uu-0 u000
EEPROM Data Register
EECON2 EEPROM Control Register 2 (not a physical register)
EECON1
IPR2
EEPGD
OSCFIP
OSCFIF
OSCFIE
CFGS
—
—
—
—
—
FREE
EEIP
EEIF
EEIE
WRERR WREN
WR
—
RD
—
—
—
LVDIP
LVDIF
LVDIE
CCP2IP 1--1 -1-1 1--1 -1-1
CCP2IF 0--0 -0-0 0--0 -0-0
CCP2IE 0--0 -0-0 0--0 -0-0
PIR2
—
—
PIE2
—
—
Legend:
x= unknown, u= unchanged, -= unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
DS39616C-page 90
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
8.2
Operation
8.0
8.1
8 x 8 HARDWARE MULTIPLIER
Introduction
Example 8-1 shows the sequence to do an 8 x 8
unsigned multiply. Only one instruction is required
when one argument of the multiply is already loaded in
the WREG register.
An 8 x 8 hardware multiplier is included in the ALU of
the PIC18F2331/2431/4331/4431 devices. By making
the multiply a hardware operation, it completes in a
single instruction cycle. This is an unsigned multiply
that gives a 16-bit result. The result is stored into the
16-bit Product register pair (PRODH:PRODL). The
multiplier does not affect any flags in the STATUS
register.
Example 8-2 shows the sequence to do an 8 x 8 signed
multiply. To account for the sign bits of the arguments,
each argument’s Most Significant bit (MSb) is tested
and the appropriate subtractions are done.
EXAMPLE 8-1:
8 x 8 UNSIGNED
MULTIPLY ROUTINE
Making the 8 x 8 multiplier execute in a single cycle
gives the following advantages:
MOVF
MULWF
ARG1, W
ARG2
;
; ARG1 * ARG2 ->
; PRODH:PRODL
• Higher computational throughput
• Reduces code size requirements for multiply
algorithms
EXAMPLE 8-2:
8 x 8 SIGNED MULTIPLY
ROUTINE
The performance increase allows the device to be used
in applications previously reserved for Digital Signal
Processors.
MOVF
MULWF
ARG1, W
ARG2
; ARG1 * ARG2 ->
; PRODH:PRODL
; Test Sign Bit
; PRODH = PRODH
Table 8-1 shows a performance comparison between
enhanced devices using the single-cycle hardware
multiply and performing the same function without the
hardware multiply.
BTFSC
SUBWF
ARG2, SB
PRODH, F
;
- ARG1
MOVF
BTFSC
SUBWF
ARG2, W
ARG1, SB
PRODH, F
; Test Sign Bit
; PRODH = PRODH
;
- ARG2
TABLE 8-1:
Routine
PERFORMANCE COMPARISON
Program
Time
@ 40 MHz @ 10 MHz @ 4 MHz
Cycles
(Max)
Multiply Method
Memory
(Words)
Without Hardware Multiply
Hardware Multiply
13
1
69
1
6.9 μs
100 ns
9.1 μs
600 ns
24.2 μs
2.4 μs
25.4 μs
3.6 μs
27.6 μs
400 ns
36.4 μs
2.4 μs
69 μs
1 μs
8 x 8 Unsigned
8 x 8 Signed
Without Hardware Multiply
Hardware Multiply
33
6
91
6
91 μs
6 μs
Without Hardware Multiply
Hardware Multiply
21
24
52
36
242
24
254
36
96.8 μs
9.6 μs
242 μs
24 μs
254 μs
36 μs
16 x 16 Unsigned
16 x 16 Signed
Without Hardware Multiply
Hardware Multiply
102.6 μs
14.4 μs
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 91
PIC18F2331/2431/4331/4431
Example 8-3 shows the sequence to do a 16 x 16
unsigned multiply. 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
(ARG1H • ARG2H • 216) +
EQUATION 8-1:
16 x 16 UNSIGNED
MULTIPLICATION
ALGORITHM
(ARG1H • ARG2L • 28) +
(ARG1L • ARG2H ² 28) +
(ARG1L • ARG2L)+
RES3:RES0
=
=
ARG1H:ARG1L • ARG2H:ARG2L
(ARG1H • ARG2H • 216) +
(ARG1H • ARG2L • 28) +
(ARG1L • ARG2H • 28) +
(ARG1L • ARG2L)
(-1 • ARG2H<7> • ARG1H:ARG1L • 216) +
(-1 • ARG1H<7> • ARG2H:ARG2L • 216)
EXAMPLE 8-4:
16 x 16 SIGNED
MULTIPLY ROUTINE
MOVF
MULWF ARG2L
ARG1L, W
EXAMPLE 8-3:
16 x 16 UNSIGNED
MULTIPLY ROUTINE
; ARG1L * ARG2L ->
; PRODH:PRODL
MOVF
MULWF ARG2L
ARG1L, W
MOVFF PRODH, RES1
MOVFF PRODL, RES0
;
;
; ARG1L * ARG2L ->
; PRODH:PRODL
;
;
;
;
MOVFF PRODH, RES1
MOVFF PRODL, RES0
MOVF
ARG1H, W
MULWF ARG2H
; ARG1H * ARG2H ->
; PRODH:PRODL
;
;
;
;
MOVF
MULWF ARG2H
ARG1H, W
MOVFF PRODH, RES3
MOVFF PRODL, RES2
; ARG1H * ARG2H ->
; PRODH:PRODL
MOVFF PRODH, RES3
MOVFF PRODL, RES2
;
;
MOVF
MULWF ARG2H
ARG1L,W
; ARG1L * ARG2H ->
; PRODH:PRODL
MOVF
ARG1L, W
MOVF
PRODL, W
;
MULWF ARG2H
; ARG1L * ARG2H ->
ADDWF RES1, F
; Add cross
; PRODH:PRODL
;
; Add cross
; products
MOVF
ADDWFC RES2, F
CLRF WREG
ADDWFC RES3, F
PRODH, W
; products
MOVF
PRODL, W
;
;
;
ADDWF RES1, F
MOVF
ADDWFC RES2, F
CLRF WREG
ADDWFC RES3, F
PRODH, W
;
;
;
;
MOVF
MULWF ARG2L
ARG1H, W
;
; ARG1H * ARG2L ->
;
; PRODH:PRODL
MOVF
ARG1H, W
;
MOVF
PRODL, W
;
MULWF ARG2L
; ARG1H * ARG2L ->
ADDWF RES1, F
; Add cross
; PRODH:PRODL
;
; Add cross
; products
MOVF
ADDWFC RES2, F
CLRF WREG
PRODH, W
; products
MOVF
PRODL, W
;
;
;
ADDWF RES1, F
MOVF
ADDWFC RES2, F
CLRF WREG
ADDWFC RES3, F
PRODH, W
ADDWFC RES3, F
;
;
;
;
;
BTFSS ARG2H, 7
; ARG2H:ARG2L neg?
; no, check ARG1
;
;
;
BRA
MOVF
SIGN_ARG1
ARG1L, W
SUBWF RES2
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, each argument pair’s Most Significant bit (MSb)
is tested and the appropriate subtractions are done.
MOVF
ARG1H, W
SUBWFB RES3
SIGN_ARG1
BTFSS ARG1H, 7
; ARG1H:ARG1L neg?
; no, done
;
;
;
BRA
MOVF
CONT_CODE
ARG2L, W
SUBWF RES2
MOVF
ARG2H, W
SUBWFB RES3
;
CONT_CODE
:
DS39616C-page 92
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
When the IPEN bit is cleared (default state), the
interrupt priority feature is disabled and interrupts are
9.0
INTERRUPTS
compatible with PIC® mid-range devices. In Compati-
bility 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
000008h in Compatibility mode.
The PIC18F2331/2431/4331/4431 devices have
multiple interrupt sources and an interrupt priority
feature that allows each interrupt source to be assigned
a high-priority level or a low-priority level. The high-
priority interrupt vector is at 000008h and the low-priority
interrupt vector is at 000018h. 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 thirteen registers which are used to control
interrupt operation. These registers are:
• RCON
• INTCON
• INTCON2
• INTCON3
The return address is pushed onto the stack and the
PC is loaded with the interrupt vector address
(000008h or 000018h). Once in the Interrupt Service
Routine, the source(s) of the interrupt can be deter-
mined by polling the interrupt flag bits. The interrupt
flag bits must be cleared in software before re-enabling
interrupts to avoid recursive interrupts.
• PIR1, PIR2, PIR3
• PIE1, PIE2, PIE3
• IPR1, IPR2, IPR3
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, each interrupt source has three bits to
control its operation. The functions of these bits are:
For external interrupt events, such as the INTx 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
• Priority bit to select high priority or low priority
(most interrupt sources have priority bits)
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.
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
interrupts 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
vector immediately to address 000008h or 000018h
depending on the priority bit setting. Individual
interrupts can be disabled through their corresponding
enable bits.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 93
PIC18F2331/2431/4331/4431
FIGURE 9-1:
INTERRUPT LOGIC
Wake-up if in
Power-Managed Mode
TMR0IF
TMR0IE
TMR0IP
RBIF
RBIE
RBIP
INT0IF
INT0IE
Interrupt to CPU
Vector to Location
0008h
INT1IF
INT1IE
INT1IP
INT2IF
INT2IE
INT2IP
TXIF
TXIE
TXIP
GIE/GIEH
ADIF
ADIE
ADIP
IPEN
IPEN
PEIE/GIEL
RCIF
RCIE
RCIP
IPEN
Additional Peripheral Interrupts
High-Priority Interrupt Generation
Low-Priority Interrupt Generation
TXIF
TXIE
TXIP
Interrupt to CPU
Vector to Location
0018h
TMR0IF
TMR0IE
TMR0IP
ADIF
ADIE
ADIP
RBIF
RBIE
RBIP
RCIF
RCIE
RCIP
PEIE/GIEL
INT0IF
INT0IE
INT1IF
INT1IE
INT1IP
Additional Peripheral Interrupts
INT2IF
INT2IE
INT2IP
DS39616C-page 94
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
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: INTERRUPT CONTROL REGISTER
R/W-0
R/W-0
PEIE/GIEL
R/W-0
R/W-0
R/W-0
RBIE
R/W-0
R/W-0
INT0IF
R/W-x
RBIF(1)
GIE/GIEH
bit 7
TMR0IE
INT0IE
TMR0IF
bit 0
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
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 high-priority 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 for RB7:RB4 pins
0= Disables the RB port change interrupt for RB7:RB4 pins
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)
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 1: A mismatch condition will continue to set this bit. Reading PORTB will end the mismatch condition and
allow the bit to be cleared.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 95
PIC18F2331/2431/4331/4431
REGISTER 9-2:
INTCON2: INTERRUPT CONTROL REGISTER 2
R/W-1
R/W-1
INTEDG0
R/W-1
R/W-1
U-0
—
R/W-1
U-0
—
R/W-1
RBIP
RBPU
bit 7
INTEDG1
INTEDG2
TMR0IP
bit 0
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
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
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.
DS39616C-page 96
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 9-3:
INTCON3: INTERRUPT CONTROL REGISTER 3
R/W-1
INT2IP
bit 7
R/W-1
U-0
—
R/W-0
R/W-0
U-0
—
R/W-0
INT2IF
R/W-0
INT1IF
INT1IP
INT2IE
INT1IE
bit 0
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
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
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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 97
PIC18F2331/2431/4331/4431
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 three Peripheral Interrupt
Request (Flag) Registers (PIR1, PIR2 and PIR3).
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
U-0
—
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 7
bit 0
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
bit 7
bit 6
Unimplemented: Read as ‘0’
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
bit 5
bit 4
bit 3
bit 2
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: 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
DS39616C-page 98
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 9-5:
PIR2: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 2
R/W-0
OSCFIF
bit 7
U-0
—
U-0
—
R/W-0
EEIF
U-0
—
R/W-0
LVDIF
U-0
—
R/W-0
CCP2IF
bit 0
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
bit 7
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
bit 6-5
bit 4
Unimplemented: Read as ‘0’
EEIF: EEPROM or 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
Unimplemented: Read as ‘0’
LVDIF: Low-Voltage Detect Interrupt Flag bit
1= The supply voltage has fallen below the specified LVD voltage (must be cleared in software)
0= The supply voltage is greater than the specified LVD voltage
bit 1
bit 0
Unimplemented: Read as ‘0’
CCP2IF: CCP2 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:
Not used in this mode.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 99
PIC18F2331/2431/4331/4431
REGISTER 9-6:
PIR3: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 3
U-0
—
U-0
—
U-0
—
R/W-0
PTIF
R/W-0
R/W-0
R/W-0
IC1IF
R/W-0
IC3DRIF
IC2QEIF
TMR5IF
bit 7
bit 0
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
bit 7-5
bit 4
Unimplemented: Read as ‘0’
PTIF: PWM Time Base Interrupt bit
1= PWM time base matched the value in the PTPER registers. Interrupt is issued according to the
postscaler settings. PTIF must be cleared in software.
0= PWM time base has not matched the value in the PTPER registers
bit 3
IC3DRIF: IC3 Interrupt Flag/Direction Change Interrupt Flag bit
IC3 Enabled (CAP3CON<3:0>):
1= TMR5 value was captured by the active edge on CAP3 input (must be cleared in software)
0= TMR5 capture has not occurred
QEI Enabled (QEIM<2:0>):
1= Direction of rotation has changed (must be cleared in software)
0= Direction of rotation has not changed
bit 2
IC2QEIF: IC2 Interrupt Flag/QEI Interrupt Flag bit
IC2 Enabled (CAP2CON<3:0>):
1= TMR5 value was captured by the active edge on CAP2 input (must be cleared in software)
0= TMR5 capture has not occurred
QEI Enabled (QEIM<2:0>):
1= The QEI position counter has reached the MAXCNT value, or the index pulse, INDX, has been
detected. Depends on the QEI operating mode enabled. Must be cleared in software.
0= The QEI position counter has not reached the MAXCNT value or the index pulse has not been
detected
bit 1
IC1 Enabled (CAP1CON<3:0>):
1= TMR5 value was captured by the active edge on CAP1 input (must be cleared in software)
0= TMR5 capture has not occurred
QEI Enabled (QEIM<2:0>), Velocity Measurement mode Enabled (VELM = 0 in QEICON register):
1= Timer5 value was captured by the active velocity edge (based on PHA or PHB input). CAP1REN
bit must be set in CAP1CON register. IC1IF must be cleared in software.
0= Timer5 value was not captured by the active velocity edge
bit 0
TMR5IF: Timer5 Interrupt Flag bit
1= Timer5 time base matched the PR5 value (must be cleared in software)
0= Timer5 time base did not match the PR5 value
DS39616C-page 100
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
9.3
PIE Registers
The PIE registers contain the individual enable bits for
the peripheral interrupts. Due to the number of peripheral
interrupt sources, there are three Peripheral Interrupt
Enable Registers (PIE1, PIE2 and PIE3). When
IPEN = 0, the PEIE bit must be set to enable any of these
peripheral interrupts.
REGISTER 9-7:
PIE1: PERIPHERAL INTERRUPT ENABLE REGISTER 1
U-0
—
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
CCP1IE
TMR2IE
TMR1IE
bit 7
bit 0
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
bit 7
bit 6
Unimplemented: Read as ‘0’
ADIE: A/D Converter Interrupt Enable bit
1= Enables the A/D interrupt
0= Disables the A/D interrupt
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
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: Synchronous Serial Port Interrupt Enable bit
1= Enables the SSP interrupt
0= Disables the SSP 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
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 101
PIC18F2331/2431/4331/4431
REGISTER 9-8:
PIE2: PERIPHERAL INTERRUPT ENABLE REGISTER 2
R/W-0
OSCFIE
bit 7
U-0
—
U-0
—
R/W-0
EEIE
U-0
—
R/W-0
LVDIE
U-0
—
R/W-0
CCP2IE
bit 0
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
bit 7
OSCFIE: Oscillator Fail Interrupt Enable bit
1= Enabled
0= Disabled
bit 6-5
bit 4
Unimplemented: Read as ‘0’
EEIE: Interrupt Enable bit
1= Enabled
0= Disabled
bit 3
bit 2
Unimplemented: Read as ‘0’
LVDIE: Low-Voltage Detect Interrupt Enable bit
1= Enabled
0= Disabled
bit 1
bit 0
Unimplemented: Read as ‘0’
CCP2IE: CCP2 Interrupt Enable bit
1= Enabled
0= Disabled
DS39616C-page 102
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 9-9:
PIE3: PERIPHERAL INTERRUPT ENABLE REGISTER 3
U-0
—
U-0
—
U-0
—
R/W-0
PTIE
R/W-0
R/W-0
R/W-0
IC1IE
R/W-0
IC3DRIE
IC2QEIE
TMR5IE
bit 7
bit 0
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
bit 7-5
bit 4
Unimplemented: Read as ‘0’
PTIE: PWM Time Base Interrupt Enable bit
1= PTIF enabled
0= PTIF disabled
bit 3
IC3DRIE: IC3 Interrupt Enable/Direction Change Interrupt Enable bit
IC3 Enabled (CAP3CON<3:0>):
1= IC3 interrupt enabled
0= IC3 interrupt disabled
QEI Enabled (QEIM<2:0>):
1= Change of direction interrupt enabled
0= Change of direction interrupt disabled
bit 2
IC2QEIE: IC2 Interrupt Flag/QEI Interrupt Flag Enable bit
IC2 Enabled (CAP2CON<3:0>):
1= IC2 interrupt enabled)
0= IC2 interrupt disabled
QEI Enabled (QEIM<2:0>):
1= QEI interrupt enabled
0= QEI interrupt disabled
bit 1
bit 0
IC1IE: IC1 Interrupt Enable bit
1= IC1 interrupt enabled
0= IC1 interrupt disabled
TMR5IE: Timer5 Interrupt Enable bit
1= Timer5 interrupt enabled
0= Timer5 interrupt disabled
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 103
PIC18F2331/2431/4331/4431
9.4
IPR Registers
The IPR registers contain the individual priority bits for
the peripheral interrupts. Due to the number of
peripheral interrupt sources, there are three peripheral
interrupt priority registers (IPR1, IPR2 and IPR3).
Using the priority bits requires that the Interrupt Priority
Enable (IPEN) bit be set.
REGISTER 9-10: IPR1: PERIPHERAL INTERRUPT PRIORITY REGISTER 1
U-0
—
R/W-1
ADIP
R/W-1
RCIP
R/W-1
TXIP
R/W-1
SSPIP
R/W-1
CCPIP
R/W-1
R/W-1
TMR2IP
TMR1IP
bit 7
bit 0
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
bit 7
bit 6
Unimplemented: Read as ‘0’
ADIP: A/D Converter Interrupt Priority bit
1= High priority
0= Low priority
bit 5
bit 4
RC1IP: EUSART Receive Interrupt Priority bit
1= High priority
0= Low priority
TX1IP: EUSART Transmit Interrupt Priority bit
1= High priority
0= Low priority
bit 3
bit 2
bit 1
bit 0
SSP1IP: 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
DS39616C-page 104
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 9-11: IPR2: PERIPHERAL INTERRUPT PRIORITY REGISTER 2
R/W-1
U-0
—
U-0
—
R/W-1
EEIP
U-0
—
R/W-1
LVDIP
U-0
—
R/W-1
OSCFIP
CCP2IP
bit 7
bit 0
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
bit 7
OSCFIP: Oscillator Fail Interrupt Priority bit
1= High priority
0= Low priority
bit 6-5
bit 4
Unimplemented: Read as ‘0’
EEIP: Interrupt Priority bit
1= High priority
0= Low priority
bit 3
bit 2
Unimplemented: Read as ‘0’
LVDIP: Low-Voltage Detect Interrupt Priority bit
1= High priority
0= Low priority
bit 1
bit 0
Unimplemented: Read as ‘0’
CCP2IP: CCP2 Interrupt Priority bit
1= High priority
0= Low priority
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 105
PIC18F2331/2431/4331/4431
REGISTER 9-12: IPR3: PERIPHERAL INTERRUPT PRIORITY REGISTER 3
U-0
—
U-0
—
U-0
—
R/W-1
PTIP
R/W-1
R/W-1
R/W-1
IC1IP
R/W-1
IC3DRIP
IC2QEIP
TMR5IP
bit 7
bit 0
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
bit 7-5
bit 4
Unimplemented: Read as ‘0’
PTIP: PWM Time Base Interrupt Priority bit
1= High priority
0= Low priority
bit 3
IC3DRIP: IC3 Interrupt Priority/Direction Change Interrupt Priority bit
IC3 Enabled (CAP3CON<3:0>):
1= IC3 interrupt high priority
0= IC3 interrupt low priority
QEI Enabled (QEIM<2:0>):
1= Change of direction interrupt high priority
0= Change of direction interrupt low priority
bit 2
IC2QEIP: IC2 Interrupt Priority/QEI Interrupt Priority bit
IC2 Enabled (CAP2CON<3:0>):
1= IC2 interrupt high priority
0= IC2 interrupt low priority
QEI Enabled (QEIM<2:0>):
1= High priority
0= Low priority
bit 1
bit 0
IC1IP: IC1 Interrupt Priority bit
1= High priority
0= Low priority
TMR5IP: Timer5 Interrupt Priority bit
1= High priority
0= Low priority
DS39616C-page 106
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
9.5
RCON Register
The RCON register contains bits used to determine the
cause of the last Reset or wake-up from a power-
managed mode. RCON also contains the bit that
enables interrupt priorities (IPEN).
REGISTER 9-13: RCON: RESET CONTROL REGISTER
R/W-0
IPEN
U-0
—
U-0
—
R/W-1
RI
R-1
TO
R-1
PD
R/W-0
POR
R/W-0
BOR
bit 7
bit 0
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
bit 7
IPEN: Interrupt Priority Enable bit
1= Enable priority levels on interrupts
0= Disable priority levels on interrupts (PIC16CXXX Compatibility mode)
bit 6-5
bit 4
Unimplemented: Read as ‘0’
RI: RESETInstruction Flag bit
For details of bit operation, see Register 5-3.
TO: Watchdog Timer Time-out Flag bit
For details of bit operation, see Register 5-3.
PD: Power-Down Detection Flag bit
bit 3
bit 2
bit 1
bit 0
For details of bit operation, see Register 5-3.
POR: Power-on Reset Status bit
For details of bit operation, see Register 5-3.
BOR: Brown-out Reset Status bit
For details of bit operation, see Register 5-3.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 107
PIC18F2331/2431/4331/4431
9.6
INTx Pin Interrupts
9.8
PORTB Interrupt-on-Change
External interrupts on the RC3/INT0, RC4/INT1 and
RC5/INT2 pins are edge-triggered; either rising if the
corresponding INTEDGx bit is set in the INTCON2
register, or falling if the INTEDGx bit is clear. When a
valid edge appears on the RC3/INT0 pin, the
corresponding flag bit, INTxIF is set. This interrupt can
be disabled by clearing the corresponding enable bit,
INTxIE. Flag bit, INTxIF, must be cleared in software in
the Interrupt Service Routine before re-enabling the
interrupt. All external interrupts (INT0, INT1 and INT2)
can wake-up the processor from the power-managed
modes if bit INTxIE was set prior to going into power-
managed modes. If the Global Interrupt Enable bit
(GIE) is set, the processor will branch to the interrupt
vector following wake-up.
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>).
9.9
Context Saving During Interrupts
During interrupts, the return PC address is saved on
the stack. Additionally, the WREG, STATUS and BSR
registers are saved on the fast return stack. If a fast
return from interrupt is not used (see Section 5.3 “Fast
Register Stack”), 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.
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.
9.7
TMR0 Interrupt
In 8-bit mode (which is the default), an overflow
(FFh → 00h) in the TMR0 register will set flag bit,
TMR0IF. In 16-bit mode, an overflow (FFFFh → 0000h)
in the TMR0H:TMR0L registers will set flag bit,
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 priority bit, TMR0IP
(INTCON2<2>). See Section 11.0 “Timer0 Module”
for further details.
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
DS39616C-page 108
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
10.1 PORTA, TRISA and LATA
Registers
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.
PORTA is an 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).
Each port has three registers for its operation. These
registers are:
Reading the PORTA register reads the status of the
pins, whereas writing to it, will write to the port latch.
• TRIS register (Data Direction register)
• PORT register (reads the levels on the pins of the
device)
The Data Latch register (LATA) is also memory mapped.
Read-modify-write operations on the LATA register read
and write the latched output value for PORTA.
• LAT register (Data Latch)
The Data Latch (LAT register) is useful for read-modify-
write operations on the value that the I/O pins are
driving.
The RA<2:4> pins are multiplexed with three input
capture pins and Quadrature Encoder Interface pins.
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
Configuration Register 1H (see Section 22.1
“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’.
A simplified model of a generic I/O port without the
interfaces to other peripherals is shown in Figure 10-1.
FIGURE 10-1:
GENERIC I/O PORT
OPERATION
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/setting the control bits in the ANSEL0 and
ANSEL1 registers.
RD LAT
Data
Bus
D
Q
I/O Pin(1)
WR LAT
or
PORT
CK
Data Latch
Note 1: On a Power-on Reset, RA5:RA0 are
configured as analog inputs and read as ‘0’.
D
Q
2: RA5 I/F is available only on 40-pin
WR TRIS
RD TRIS
devices (PIC18F4331/4431).
CK
TRIS Latch
Input
Buffer
The TRISA register controls the direction of the RA
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.
Q
D
EXAMPLE 10-1:
INITIALIZING PORTA
CLRF
PORTA
LATA
0x3F
; Initialize PORTA by
; clearing output
; data latches
; Alternate method
; to clear output
; data latches
EN
RD PORT
CLRF
Note 1: I/O pins have diode protection to VDD and VSS.
MOVLW
MOVWF
MOVLW
; Configure A/D
ANSEL0 ; for digital inputs
0xCF
; Value used to
; initialize data
; direction
MOVWF
TRISA
; Set RA<3:0> as inputs
; RA<5:4> as outputs
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 109
PIC18F2331/2431/4331/4431
FIGURE 10-2:
BLOCK DIAGRAM OF RA0
FIGURE 10-3:
BLOCK DIAGRAM OF RA1
VDD
P
RD LATA
Data
Bus
RD LATA
D
Q
Data Bus
D
Q
VDD
P
WR LATA
or PORTA
RA1
WR LATA
or PORTA
Q
CK
Q
CK
N
Data Latch
Data Latch
VSS
Q
D
N
I/O Pin
D
Q
WR TRISA
CK
Q
Analog
Input
WR TRISA
VSS
Analog
TRIS Latch
RD TRISA
Q
CK
Mode
Input
Mode
TRIS Latch
TTL
TTL
RD TRISA
Q
D
Q
Input
Buffer
D
EN
RD PORTA
EN
RD PORTA
To A/D Converter
To A/D Converter
FIGURE 10-4:
BLOCK DIAGRAM OF RA3:RA2
VDD
P
RD LATA
Data Bus
Q
Q
D
WR LATA
or PORTA
I/O Pin
CK
Data Latch
N
Q
Q
D
VSS
WR TRISA
CK
Analog
Input
Mode
TRIS Latch
Schmitt
Trigger
Input
TTL
RD TRISA
Buffer
D
Q
EN
RD PORTA
To A/D Converter
To CAP1/INDX or CAP2/QEA
DS39616C-page 110
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 10-5:
BLOCK DIAGRAM OF RA4
RD LATA
Data
Bus
D
Q
VDD
P
WR LATA
or PORTA
CK
Q
Data Latch
D
Q
RA4(1)
N
VSS
WR TRISA
CK
TRIS Latch
Q
Schmitt
Trigger
Input
Analog
Input
Mode
Buffer
TTL
Input
Buffer
RD TRISA
D
Q
EN
RD PORTA
To A/D Converter
To CAP3/QEB
Note 1: Open-drain usually available on RA4 has been removed for this device.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 111
PIC18F2331/2431/4331/4431
FIGURE 10-6:
BLOCK DIAGRAM OF RA5
FIGURE 10-8:
BLOCK DIAGRAM OF RA7
INTOSC Enable
Data
Bus
RD LATA
Data
Bus
To
Q
D
Oscillator
RD LATA
VDD
P
WR LATA
or PORTA
Q
D
Q
CK
VDD
P
WR LATA
or PORTA
Data Latch
CK
Q
N
I/O Pin
D
Q
Data Latch
N
I/O Pin
D
Q
WR TRISA
VSS
Q
CK
Analog
Input
TRIS Latch
VSS
CK
Q
Mode or
LVDIN
Enabled
TRIS Latch
RD TRISA
INTOSC
w/RA7 Enable
TTL
RD TRISA
Input
Buffer
TTL
Input
Buffer
Q
D
EN
Q
D
RD PORTA
EN
To A/D Converter/LVD Module Input
RD PORTA
FIGURE 10-7:
BLOCK DIAGRAM OF RA6
EC/ECIO or RC/RCIO
Enable
Data
Bus
To
Oscillator
RD LATA
D
Q
VDD
P
WR LATA
or PORTA
CK
Q
Data Latch
N
I/O Pin
D
Q
VSS
Q
CK
TRIS Latch
RD TRISA
EC/ECIO or
RC/RCIO Enable
TTL
Input
Buffer
Q
D
EN
RD PORTA
DS39616C-page 112
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 10-1: PORTA FUNCTIONS
Name
Bit #
Buffer
Function
RA0/AN0
RA1/AN1
bit 0
bit 1
bit 2
TTL
TTL
Input/output or analog input.
Input/output or analog input.
RA2/AN2/VREF-/CAP1/INDX
RA3/AN3/VREF+/CAP2/QEA
RA4/AN4/CAP3/QEB
TTL/ST Input/output, analog input, VREF-, capture input or QEI index
input.
bit 3
bit 4
TTL/ST Input/output, analog input, VREF+, capture input or Quadrature
Channel A input.
TTL/ST Input/output, analog input, capture input or Quadrature
Channel B input.
RA5/AN5/LVDIN(1)
OSC2/CLKO/RA6
OSC1/CLKI/RA7
bit 5
bit 6
bit 7
TTL
TTL
TTL
Input/output, analog input or Low-Voltage Detect input.
OSC2, clock output or I/O pin.
OSC1, clock input or I/O pin.
Legend: TTL = TTL input, ST = Schmitt Trigger input
Note 1: Only available on PIC18F4331/4431 devices.
TABLE 10-2: SUMMARY OF REGISTERS ASSOCIATED WITH PORTA
Value on
all other
Resets
Value on
POR, BOR
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
PORTA
LATA
RA7(1)
RA6(1)
RA5
RA4
RA3
RA2
RA1
RA0 xx0x 0000 uu0u 0000
xxxx xxxx uuuu uuuu
LATA7(1) LATA6(1) LATA Data Output Register
TRISA
TRISA7(1) TRISA6(1) PORTA Data Direction Register
1111 1111 1111 1111
ADCON1 VCFG1
ANSEL0 ANS7(2) ANS6(2) ANS5(2) ANS4
ANSEL1
VCFG0
—
FIFOEN BFEMT BFOVFL ADPNT1 ADPNT0 00-0 0000 00-1 0000
ANS3
—
ANS2
—
ANS1
—
ANS0 1111 1111 1111 1111
ANS8(2) ---- ---1 ---- ---1
—
—
—
—
Legend: x= unknown, u= unchanged, -= 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’.
2: ANS5 through ANS8 are available only on the PIC18F4331/4431 devices.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 113
PIC18F2331/2431/4331/4431
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 Sleep. 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), PORTB instruction). This will
end the mismatch condition.
EXAMPLE 10-2:
INITIALIZING PORTB
b) Clear flag bit RBIF.
CLRF
PORTB
; Initialize PORTB by
; clearing 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
LATB
; Alternate method
; to clear output
; data latches
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
0xCF
; Value used to
; initialize data
; direction
; Set RB<3:0> as inputs
; RB<5:4> as outputs
; RB<7:6> as inputs
TRISB
RB<0:3> and RB4 pins are multiplexed with the 14-bit
PWM module for PWM<0:3> and PWM5 output. The
RB5 pin can be configured by the Configuration bit
PWM4MX as the alternate pin for PWM4 output.
Each of the PORTB pins has a weak internal pull-up. A
single control bit can turn on all the pull-ups. This is
performed 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.
DS39616C-page 114
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 10-9:
BLOCK DIAGRAM OF RB3:RB0
VDD
Weak
RBPU(1)
P
Pull-up
PORT/PWM Select
PWM0, 1, 2, 3 Data
0
1
VDD
P
RD LATB
Data Bus
Q
D
WR LATB
or PORTB
RB<3:0> Pins
Q
CK
Data Latch
N
D
Q
VSS
WR TRISB
CK
Q
TTL
Input
Buffer
TRIS Latch
RD TRISB
Q
D
EN
RD PORTB
Note 1: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit (INTCON2<7>).
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 115
PIC18F2331/2431/4331/4431
FIGURE 10-10:
BLOCK DIAGRAM OF RB4
VDD
Weak
RBPU(1)
P
Pull-up
PORT/PWM Select
PWM5 Data
0
1
VDD
P
RD LATB
Data Bus
D
Q
RB4 Pin
WR LATB
or PORTB
Q
CK
Data Latch
N
D
Q
Q
VSS
WR TRISB
CK
TTL
Input
Buffer
TRIS Latch
RD TRISB
RD LATB
D
Q
EN
Q1
RD PORTB
Set RBIF
Q
D
From other
RB7:RB4 pins
RD PORTB
Q3
EN
Note 1: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit (INTCON2<7>).
DS39616C-page 116
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 10-11:
BLOCK DIAGRAM OF RB5
PORT/PWM Select
0
1
PWM4 Data
VDD
P
N
VSS
VDD
RBPU
Weak
Pull-up
P
Data Bus
D
Q
Q
RB5/PGM
WR PORTB
CK
Data Latch
D
Q
WR TRISB
CK
TRIS Latch
TTL
Input
Buffer
Schmitt
Trigger
RD TRISB
Q
D
RD PORTB
Q1
EN
Set RBIF
Q
D
From other
RB7:RB4 pins
RD PORTB
Q3
EN
LVP Configuration Bit:
1= Low-Voltage Programming Enable
0= Only High-Voltage Programming
Enable ICSP™
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 117
PIC18F2331/2431/4331/4431
FIGURE 10-12:
BLOCK DIAGRAM OF RB7:RB6
Enable Debug or ICSP™
RBPU(1)
VDD
P
Weak
Pull-up
0
1
RD LATB
Enable
Debug
Data Bus
Q
D
RB7/RB6 Pin
WR LATB
or PORTB
RBx
Q
CK
0
1
Data Latch
Enable
Debug
D
Q
TRISBx
WR TRISB
CK
Q
TRIS Latch
RD TRISB
TTL
Input
Buffer
Schmitt
Trigger
D
Q
RD PORTB
Enable Debug
or ICSP™
Q1
EN
Set RBIF
D
Q
RD PORTB
Q3
From other
RB7:RB4 pins
EN
PGC(2)/PGD(3)
Note 1: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit (INTCON2<7>).
2: PGC is available on RB6.
3: PGD is available on RB7.
DS39616C-page 118
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 10-3: PORTB FUNCTIONS
Name
Bit #
Buffer
Function
RB0/PWM0
bit 0
TTL(1)
Input/output pin or PCPWM output PWM0. Internal software
programmable weak pull-up.
RB1/PWM1
bit 1
bit 2
bit 3
bit 4
bit 5
TTL(1)
TTL(1)
TTL(1)
TTL
Input/output pin or PCPWM output PWM1. Internal software
programmable weak pull-up.
RB2/PWM2
Input/output pin or PCPWM output PWM2. Internal software
programmable weak pull-up.
RB3/PWM3
Input/output pin or PCPWM output PWM3. Internal software
programmable weak pull-up.
RB4/KBI0/PWM5
Input/output pin (with interrupt-on-change) or PCPWM output PWM5.
Internal software programmable weak pull-up.
RB5/KBI1/PWM4/
PGM(3)
TTL/ST(2) Input/output pin (with interrupt-on-change) or PCPWM output PWM4.
Internal software programmable weak pull-up.
Low-Voltage ICSP™ enable pin.(3)
RB6/KBI2/PGC
RB7/KBI3/PGD
bit 6
bit 7
TTL/ST(2) Input/output pin (with interrupt-on-change). Internal software
programmable weak pull-up. Serial programming clock.
TTL/ST(2) Input/output pin (with interrupt-on-change). Internal software
programmable weak pull-up. Serial programming data.
Legend: TTL = TTL input, ST = Schmitt Trigger input
Note 1: This buffer is a TTL input when configured as digital I/O.
2: This buffer is a Schmitt Trigger input when used in Serial Programming mode.
3: Low-Voltage Programming must be enabled.
TABLE 10-4: SUMMARY OF REGISTERS ASSOCIATED WITH PORTB
Value on
all other
Resets
Value on
POR, BOR
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
PORTB
LATB
RB7
RB6
RB5
RB4
RB3
RB2
RB1
RB0
xxxx xxxx
xxxx xxxx
1111 1111
0000 000x
1111 -1-1
uuuu uuuu
uuuu uuuu
1111 1111
0000 000u
1111 -1-1
11-0 0-00
LATB Data Output Register
TRISB
PORTB Data Direction Register
GIE/GIEH PEIE/GIEL TMR0IE
INTCON
INTCON2
INTCON3
Legend:
INT0IE
RBIE
—
TMR0IF INT0IF
RBIF
RBIP
RBPU
INTEDG0 INTEDG1 INTEDG2
INT1IP INT2IE
TMR0IP
—
—
INT2IP
—
INT1IE
INT2IF
INT1IF 11-0 0-00
x= unknown, u= unchanged, q= value depends on condition, -= unimplemented, read as ‘0’.
Shaded cells are not used by PORTB.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 119
PIC18F2331/2431/4331/4431
External interrupts, IN0, INT1 and INT2, are placed on
RC3, RC4 and RC5 pins, respectively.
10.3 PORTC, TRISC and LATC
Registers
SSP alternate interface pins, SDI/SDA, SCK/SCL and
SDO are placed on RC4, RC5 and RC7 pins,
respectively.
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).
These pins are multiplexed on PORTC and PORTD by
using the SSPMX bit in the CONFIG3L register.
EUSART pins RX/DT and TX/CK are placed on RC7
and RC6 pins, respectively.
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.
The alternate Timer5 external clock input, T5CKI, and
the alternate TMR0 external clock input, T0CKI, are
placed on RC3 and are multiplexed with the PORTD
(RD0) pin using the EXCLKMX Configuration bit in
CONFIG3H. Fault inputs to the 14-bit PWM module,
FLTA and FLTB, are located on RC1 and RC2. FLTA
input on RC1 is multiplexed with RD4 using the
FLTAMX bit.
PORTC is multiplexed with several peripheral functions
(Table 10-5). The pins have Schmitt Trigger input
buffers.
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 the correct TRIS bit settings.
EXAMPLE 10-3:
INITIALIZING PORTC
CLRF
PORTC
; Initialize PORTC by
; clearing output
; data latches
CLRF
LATC
; Alternate method
; to clear output
; data latches
Note: On a Power-on Reset, these pins are
configured as digital inputs.
MOVLW
MOVWF
0xCF
; Value used to
; initialize data
; direction
; Set RC<3:0> as inputs
; RC<5:4> as outputs
; RC<7:6> as inputs
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.
TRISC
FIGURE 10-13:
BLOCK DIAGRAM OF RC0
VDD
P
RD LATC
Data Bus
D
Q
WR LATC
or PORTC
RC0 Pin
Q
CK
Data Latch
N
D
Q
VSS
WR TRISC
T1OSCEN
Q
CK
Timer1
Oscillator
TRIS Latch
RD TRISC
Schmitt
Trigger
To RC1 Pin
Q
D
EN
RD PORTC
TMR1 Clock Input
DS39616C-page 120
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 10-14:
BLOCK DIAGRAM OF RC1
PORT/CCP2 Select
CCP2 Data Out
0
1
To RC0 Pin
VDD
P
RD LATC
Q
Data Bus
D
WR LATC
or PORTC
RC1 Pin
CK
Q
Data Latch
N
D
Q
Q
VSS
WR TRISC
CK
TRIS Latch
FLTAMX
Schmitt
Trigger
RD TRISC
Q
D
EN
RD PORTC
CCP2 Input
FLTA Input(1)
Note 1: FLTA input is multiplexed with RC1 and RD4 using FLTAMX Configuration bit in CONFIG3H register.
FIGURE 10-15:
BLOCK DIAGRAM OF RC2
PORT/CCP1 Select
CCP1 Data Out
0
1
VDD
P
RD LATC
Data Bus
D
Q
WR LATC
or PORTC
RC2 Pin
Q
CK
Data Latch
N
Q
Q
D
VSS
WR TRISC
CK
TRIS Latch
RD TRISC
Schmitt
Trigger
D
Q
EN
RD PORTC
CCP1 Input/FLTB Input
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 121
PIC18F2331/2431/4331/4431
FIGURE 10-16:
BLOCK DIAGRAM OF RC3
VDD
P
RD LATC
Data Bus
D
Q
Q
WR LATC
or PORTC
RC3 Pin
CK
Data Latch
N
D
Q
Q
VSS
WR TRISC
CK
TRIS Latch
EXCLKMX_enable(1)
Schmitt
Trigger
RD TRISC
Q
D
EN
RD PORTC
T0CKI/T5CKI Input
Note 1: The T0CKI/T5CKI bit is multiplexed with RD0 when the EXCLKMX is enabled (= 1) in the Configuration register.
FIGURE 10-17:
BLOCK DIAGRAM OF RC4
PORT/SSP Mode & SSPMX Select
SDA Data Out
0
1
VDD
P
RD LATC
Data Bus
D
Q
WR LATC
or PORTC
RC4 Pin
CK
Q
Data Latch
N
D
Q
VSS
WR TRISC
SDA Drive
CK
Q
TRIS Latch
SSPMX(1)
RD TRISC
Schmitt
Trigger
D
Q
EN
RD PORTC
SDI/SDA Input
Note 1: The SDI/SDA bits are multiplexed with RD2 and RC4 pins by the SSPMX bit in the Configuration register.
DS39616C-page 122
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 10-18:
BLOCK DIAGRAM OF RC5
I2C™ Mode
PORT/SSPEN & SSPMX_Select
SCK/SCL Data Out
0
VDD
P
1
RD LATC
Data Bus
D
Q
WR LATC
or PORTC
RC5 Pin
CK
Q
Data Latch
N
D
Q
VSS
WR TRISC
SDO Drive
CK
Q
TRIS Latch
SSPMX(1)
Schmitt
Trigger
RD TRISC
D
Q
EN
RD PORTC
SCL or SCL Input
Note 1: SCK/SCL are multiplexed on RD3 and RC5 using SSPMX bit in the Configuration register.
FIGURE 10-19:
BLOCK DIAGRAM OF RC6
EUSART Select
TX Data Out/CK
0
1
VDD
P
RD LATC
Q
Data Bus
D
WR LATC
or PORTC
RC6 Pin
CK
Q
Data Latch
N
D
Q
Q
VSS
WR TRISC
CK
TRIS Latch
RD TRISC
TTL
Schmitt
Trigger
EUSART Select
D
Q
EN
RD PORTC
CK Input
SS Input
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 123
PIC18F2331/2431/4331/4431
FIGURE 10-20:
BLOCK DIAGRAM OF RC7
EUSART Select (1)
DT Data Out
PORT/(SSPEN * SPI Mode) Select
0
1
SDO Data Out(2)
0
1
VDD
P
RD LATC
Data Bus
D
Q
WR LATC
or PORTC
RC7 Pin
CK
Q
Data Latch
N
D
Q
VSS
WR TRISC
CK
Q
TRIS Latch
RD TRISC
Schmitt
Trigger
EUSART Select(1)
D
Q
EN
RD PORTC
RX/DT Data Input
Note 1: EUSART is in Synchronous Master Transmission mode only (SYNC = 1, TXEN = 1).
2: SDO must have its TRISC bit cleared in order to be able to drive RC7.
DS39616C-page 124
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 10-5: PORTC FUNCTIONS
Buffer
Name
Bit #
Function
Type
RC0/T1OSO/T1CKI
bit 0
ST
Input/output port pin or Timer1 oscillator output/Timer1 clock input.
RC1/T1OSI/CCP2/FLTA bit 1 ST/CMOS Input/output port pin, Timer1 oscillator input, Capture2 input/
Compare2 output/PWM output when CCP2Mx bit is disabled or FLTA
input.
RC2/CCP1/FLTB
bit 2
ST
ST
ST
ST
ST
ST
Input/output port pin, Capture1 input/Compare1 output/PWM1 output
or FLTB input.
RC3/T0CKI/T5CKI/INT0 bit 3
Input/output port pin, Timer0 and Timer5 alternate clock input or
external interrupt 0.
Input/output port pin, SPI data in, I2C™ data I/O or external
RC4/INT1/SDI/SDA
RC5/INT2/SCK/SCL
RC6/TX/CK/SS
bit 4
bit 5
bit 6
bit 7
interrupt 1.
Input/output port pin, Synchronous Serial Port clock I/O or external
interrupt 2.
Input/output port pin, EUSART asynchronous transmit,
EUSART synchronous clock or SPI slave select input.
RC7/RX/DT/SDO
Input/output port pin, EUSART asynchronous receive, EUSART
synchronous data or SPI data out.
Legend: ST = Schmitt Trigger input
TABLE 10-6: SUMMARY OF REGISTERS ASSOCIATED WITH PORTC
Value on
all other
Resets
Value on
POR, BOR
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
PORTC
LATC
RC7
RC6
RC5
RC4
RC3
RC2
RC1
RC0
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
1111 1111 1111 1111
0000 000x 0000 000u
1111 -1-1 1111 -1-1
LATC Data Output Register
TRISC
PORTC Data Direction Register
INTCON GIE/GIEH PEIE/GIEL TMR0IE
INTCON2 RBPU
INTCON3 INT2IP
Legend:
INT0IE
RBIE
—
TMR0IF
TMR0IP
—
INT0IF
—
RBIF
RBIP
INTEDG0 INTEDG1 INTEDG2
INT1IP INT2IE
—
INT1IE
INT2IF
INT1IF 11-0 0-00 11-0 0-00
x= unknown, u= unchanged, - = unimplemented, read as ‘0’.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 125
PIC18F2331/2431/4331/4431
PORTD includes PWM<7:6> complementary fourth
10.4 PORTD, TRISD and LATD
Registers
channel PWM outputs. PWM4 is the complementary
output of PWM5 (the third channel), which is multi-
plexed with the RB5 pin. This output can be used as the
alternate output using the PWM4MX Configuration bit
in CONFIG3H when the Low-Voltage Programming pin
(PGM) is used on RB5.
Note: PORTD is only available on PIC18F4331/
4431 devices.
PORTD is an 8-bit wide, bidirectional port. The
corresponding 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).
RD1, RD2 and RD3 can be used as the alternate out-
put for SDO, SDI/SDA and SCK/SCL using the SSPMX
Configuration bit in CONFIG3H.
RD4 an be used as the alternate output for FLTA using
the FLTAMX Configuration bit in CONFIG3H.
EXAMPLE 10-4:
INITIALIZING PORTD
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
PORTD
; Initialize PORTD by
; clearing output
; data latches
; Alternate method
; to clear output
; data latches
; Value used to
; initialize data
; direction
CLRF
LATD
All pins on PORTD are implemented with Schmitt
Trigger input buffers. Each pin is individually
configurable as an input or output.
MOVLW
MOVWF
0xCF
Note: On a Power-on Reset, these pins are
configured as digital inputs.
TRISD
; Set RD<3:0> as inputs
; RD<5:4> as outputs
; RD<7:6> as inputs
FIGURE 10-21:
BLOCK DIAGRAM OF RD7:RD6
PORT/PWM Select
PWM6, 7 Data Out
0
1
VDD
P
RD LATD
Q
Data Bus
D
WR LATD
or PORTD
RD<7:6> Pin
CK
Q
Data Latch
N
D
Q
Q
VSS
WR TRISD
CK
TRIS Latch
RD TRISD
Schmitt
Trigger
Q
D
EN
RD PORTD
DS39616C-page 126
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 10-22:
BLOCK DIAGRAM OF RD5
PORT/PWM Select
PWM4 Data Out*
0
1
VDD
P
RD LATD
Q
Data Bus
D
WR LATD
or PORTD
RD5 Pin
CK
Q
Data Latch
N
D
Q
Q
VSS
WR TRISD
CK
TRIS Latch
RD TRISD
Schmitt
Trigger
Q
D
EN
RD PORTD
FIGURE 10-23:
BLOCK DIAGRAM OF RD4
VDD
P
RD LATD
Data Bus
D
Q
WR LATD
or PORTD
RD4 Pin
CK
Q
Data Latch
N
D
Q
VSS
WR TRISD
CK
Q
TRIS Latch
RD TRISD
FLTAMX(1)
Schmitt
Trigger
Schmitt
Trigger
Q
D
EN
RD PORTD
FLTA Input
Note 1: FLTAMX is located in the Configuration register, CONFIG3H.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 127
PIC18F2331/2431/4331/4431
FIGURE 10-24:
BLOCK DIAGRAM OF RD3
I2C™ Mode
PORT/SSPEN & SSPMX Select
SCK/SCL Data Out
0
1
VDD
P
RD LATD
Data Bus
D
Q
WR LATD
or PORTD
RD3 Pin
CK
Q
Data Latch
N
D
Q
VSS
WR TRISD
CK
Q
TRIS Latch
RD TRISD
SSPMX(1)
Schmitt
Trigger
D
Q
EN
RD PORTD
SCK or SCL Input
Note 1: SCK/SCL are multiplexed on RD3 and RC5 using the SSPMX bit in the Configuration register.
FIGURE 10-25:
BLOCK DIAGRAM OF RD2
PORT/SSP Mode & SSPMX Select
SDA Data Out
0
1
VDD
P
RD LATD
Q
Data Bus
D
WR LATD
or PORTD
RD2 Pin
CK
Q
Data Latch
N
D
Q
Q
VSS
WR TRISD
SDA Drive
CK
TRIS Latch
SSPMX(1)
RD TRISD
Schmitt
Trigger
Q
D
EN
RD PORTD
SDI/SDA Input
Note 1: The SDI/SDA bits are multiplexed on RD2 and RC4 pins by the SSPMX bit in the Configuration register.
DS39616C-page 128
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 10-26:
BLOCK DIAGRAM OF RD1
PORT/SPI Mode & SSPMX Select
SDO Data Out
0
1
VDD
P
RD LATD
Q
Data Bus
D
WR LATD
or PORTD
RD1 Pin
CK
Q
Data Latch
N
D
Q
Q
VSS
WR TRISD
CK
TRIS Latch
Schmitt
Trigger
RD TRISD
Q
D
EN
RD PORTD
Note 1: The SDO output is multiplexed by the SSPMX bit in the Configuration register.
FIGURE 10-27:
BLOCK DIAGRAM OF RD0
VDD
P
RD LATD
Data Bus
D
Q
WR LATD
or PORTD
RD0 Pin
CK
Q
Data Latch
N
D
Q
VSS
WR TRISD
CK
Q
TRIS Latch
RD TRISD
Schmitt
Trigger
SSPMX(1)
D
Q
EN
RD PORTD
T0CKI/T5CKI Input
Note 1: T0CKI/T5CKI are multiplexed by the SSPMX bit in the Configuration register.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 129
PIC18F2331/2431/4331/4431
TABLE 10-7: PORTD FUNCTIONS
Name
Bit #
Buffer Type
Function
RD0/T0CKI/T5CKI
RD1/SDO
bit 0
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 7
ST
ST
ST
ST
ST
ST
ST
ST
Input/output port pin.
Input/output port pin.
Input/output port pin.
Input/output port pin.
Input/output port pin.
RD2/SDI/SDA
RD3/SCK/SCL
RD4/FLTA(1)
RD5/PWM4(2)
RD6/PWM6
Input/output port pin or PCPWM output PWM4.
Input/output port pin or PCPWM output PWM6.
Input/output port pin or PCPWM output PWM7.
RD7/PWM7
Legend: ST = Schmitt Trigger input, TTL = TTL input
Note 1: RD4 is the alternate pin for FLTA.
2: RD5 is the alternate pin for PWM4.
TABLE 10-8: SUMMARY OF REGISTERS ASSOCIATED WITH PORTD
Value on
all other
Resets
Value on
POR, BOR
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
xxxx xxxx
xxxx xxxx
1111 1111
uuuu uuuu
uuuu uuuu
1111 1111
LATD Data Output Register
TRISD
Legend:
PORTD Data Direction Register
x= unknown, u= unchanged, – = unimplemented, read as ‘0’.
DS39616C-page 130
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
The fourth pin of PORTE (MCLR/VPP/RE3) is an input
only pin. Its operation is controlled by the MCLRE
Configuration bit in Configuration Register 3H
(CONFIG3H<7>). When selected as a port pin
(MCLRE = 0), it functions as a digital input-only pin. As
such, it does not have TRIS or LAT bits associated with
10.5 PORTE, TRISE and LATE
Registers
Note:
PORTE is only available on PIC18F4331/
4431 devices.
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.
PORTE is a 4-bit wide bidirectional port. Three pins
(RE0/AN6, RE1/AN67 and RE2/AN8) 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 a
digital input only if Master Clear functionality
is disabled.
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
; Initialize PORTE by
; clearing output
; data latches
CLRF
LATE
; Alternate method
; to clear output
; data latches
; Configure A/D
; for digital inputs
;
; Value used to
; initialize data
; direction
; Set RE<0> as input
; RE<1> as output
; RE<2> as input
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
BCF
0x3F
ANSEL0
ANSEL1, 0
0x03
Note: On a Power-on Reset, RE2:RE0 are
MOVLW
configured as analog inputs.
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.
MOVWF
TRISE
10.5.1
PORTE IN 28-PIN DEVICES
For PIC18F2331/2431 devices, PORTE is only
available when master clear functionality is disabled
(CONFIG3H<7> = 0). In these cases, PORTE is a
single bit, input-only port comprised of RE3 only. The
pin operates as previously described.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 131
PIC18F2331/2431/4331/4431
FIGURE 10-28:
BLOCK DIAGRAM OF RE2:RE0
VDD
P
RD LATE
Data Bus
D
Q
WR LATE
or PORTE
RE<2:0> Pins
CK
Q
Data Latch
N
D
Q
WR TRISE
VSS
CK
Q
TRIS Latch
RD TRISE
Analog
Input
Mode
Schmitt
Trigger
D
Q
EN
RD PORTE
To A/D Converter Channel AN6, AN7 or AN8
FIGURE 10-29:
BLOCKDIAGRAM OFRE3
MCLR/VPP/RE3(1)
MCLRE
Data Bus
RD TRISE
Schmitt
Trigger
RD LATE
Latch
D
Q
EN
RD PORTE
High-Voltage Detect
Internal MCLR
HV
MCLRE
FILTER
Low-Level
MCLR Detect
Note 1: Pin requires special protection due to HV.
DS39616C-page 132
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 10-1: TRISE REGISTER
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
R/W-1
R/W-1
R/W-1
TRISE2
TRISE1
TRISE0
bit 7
bit 0
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
bit 7-3
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
TABLE 10-9:
Name
PORTE FUNCTIONS
Bit #
Buffer Type
Function
RE0/AN6
bit 0
bit 1
bit 2
bit 3
ST
ST
ST
ST
Input/output port pin or analog input.
Input/output port pin or analog input.
Input/output port pin or analog input.
RE1/AN7
RE2/AN8
MCLR/VPP/RE3
Input only port pin or programming voltage input (if MCLR is disabled);
Master Clear input or programming voltage input (if MCLR is enabled).
Legend: ST = Schmitt Trigger input
TABLE 10-10: SUMMARY OF REGISTERS ASSOCIATED WITH PORTE
Value on
all other
Resets
Value on
POR, BOR
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
(1)
PORTE
LATE
—
—
—
—
—
—
—
—
—
—
—
RE3
—
RE2
RE1
RE0
---- q000 ---- q000
---- -xxx ---- -uuu
LATE Data Output Register
TRISE
—
—
PORTE Data Direction Register ---- -111 ---- -111
(2)
(2)
(2)
ANSEL0
ANSEL1
Legend:
ANS7
—
ANS6
—
ANS5
—
ANS4
—
ANS3
—
ANS2
—
ANS1
—
ANS0
1111 1111 1111 1111
---- ---1 ---- ---1
(2)
ANS8
x= unknown, u= unchanged, -= unimplemented, read as ‘0’, q = value depends on condition.
Shaded cells are not used by PORTE.
Note 1: Implemented only when Master Clear functionality is disabled (CONFIG3H<7> = 0).
2: ANS5 through ANS8 are available only on PIC18F4331/4431 devices.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 133
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 134
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Figure 11-1 shows a simplified block diagram of the
Timer0 module in 8-bit mode and Figure 11-2 shows a
simplified block diagram of the Timer0 module in 16-bit
mode.
11.0 TIMER0 MODULE
The Timer0 module has the following features:
• Software selectable as an 8-bit or
16-bit timer/counter
The T0CON register (Register 11-1) is a readable and
writable register that controls all the aspects of Timer0,
• Readable and writable
including the prescale selection.
• Dedicated 8-bit software programmable prescaler
• Clock source selectable to be external or internal
• Interrupt-on-overflow from FFh to 00h in 8-bit
mode and FFFFh to 0000h in 16-bit mode
• Edge select for external clock
REGISTER 11-1: T0CON: TIMER0 CONTROL REGISTER
R/W-1
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
TMR0ON
T016BIT
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2-0
TMR0ON: Timer0 On/Off Control bit
1= Enables Timer0
0= Stops Timer0
T016BIT: Timer0 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.
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
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 135
PIC18F2331/2431/4331/4431
FIGURE 11-1:
TIMER0 BLOCK DIAGRAM IN 8-BIT MODE
Data Bus
8
FOSC/4
0
1
T0CKI Pin
1
Sync with
Internal
Clocks
TMR0
Programmable
Prescaler
0
(2 TCY Delay)
T0SE
3
PSA
Set Interrupt
Flag bit TMR0IF
on Overflow
T0PS2, T0PS1, T0PS0
T0CS
Note: Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI maximum prescale.
FIGURE 11-2:
TIMER0 BLOCK DIAGRAM IN 16-BIT MODE
FOSC/4
0
T0CKI Pin
1
Sync with
Internal
Clocks
Set Interrupt
Flag bit TMR0IF
on Overflow
TMR0
1
TMR0L
High Byte
Programmable
Prescaler
0
8
(2 TCY Delay)
T0SE
3
Read TMR0L
Write TMR0L
T0PS2, T0PS1, T0PS0
PSA
T0CS
8
8
TMR0H
8
Data Bus<7:0>
Note: Upon Reset, Timer0 is enabled in 16-bit mode with clock input from T0CKI maximum prescale.
DS39616C-page 136
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
11.2.1
SWITCHING PRESCALER
ASSIGNMENT
11.1 Timer0 Operation
Timer0 can operate as a timer or as a counter.
The prescaler assignment is fully under software con-
trol (i.e., it can be changed “on-the-fly” during program
execution).
Timer mode is selected by clearing the T0CS bit. In
Timer mode, the Timer0 module will increment every
instruction cycle (without prescaler). If the TMR0 regis-
ter is written, 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.
11.3 Timer0 Interrupt
The TMR0 interrupt is generated when the TMR0
register overflows from FFh to 00h in 8-bit mode, or
FFFFh to 0000h in 16-bit mode. This overflow sets the
TMR0IF bit. The interrupt can be masked by clearing
the TMR0IE bit. The TMR0IF bit must be cleared in
software by the Timer0 module Interrupt Service
Routine before re-enabling this interrupt. The TMR0
interrupt cannot awaken the processor from Sleep
mode, since the timer requires clock cycles, even when
T0CS is set.
Counter mode is selected by setting the T0CS bit. In
Counter mode, Timer0 will increment, either on every
rising or falling edge of pin RC3/T0CKI. The increment-
ing edge is determined by the Timer0 Source Edge
Select bit (T0SE). Clearing the T0SE bit selects the
rising edge.
When an external clock input is used for Timer0, it must
meet certain requirements. The requirements ensure
the external clock can be synchronized with the internal
phase clock (TOSC). Also, there is a delay in the actual
incrementing of Timer0 after synchronization.
11.4 16-Bit Mode Timer Reads and
Writes
11.2 Prescaler
TMR0H is not the high byte of the timer/counter in
16-bit mode, but is actually a buffered version of the
high byte of Timer0 (refer to Figure 11-2). The high byte
of the Timer0 counter/timer is not directly readable nor
writable. TMR0H is updated with the contents of the
high byte of Timer0 during a read of TMR0L. This pro-
vides 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.
An 8-bit counter is available as a prescaler for the Timer0
module. The prescaler is not readable or writable.
The PSA and T0PS2:T0PS0 bits determine the
prescaler assignment and prescale ratio.
Clearing bit PSA will assign the prescaler to the Timer0
module. When the prescaler is assigned to the Timer0
module, prescale values of 1:2, 1:4, ..., 1:256 are
selectable.
When assigned to the Timer0 module, all instructions
writing to the TMR0 register (e.g., CLRF TMR0, MOVWF
TMR0, BSF TMR0, x..., etc.) will clear the prescaler
count.
A write to the high byte of Timer0 must also take place
through the TMR0H Buffer register. Timer0 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.
Note:
Writing to TMR0 when the prescaler is
assigned to Timer0 will clear the prescaler
count, but will not change the prescaler
assignment.
TABLE 11-1: REGISTERS ASSOCIATED WITH TIMER0
Value on
all other
Resets
Value on
POR, BOR
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TMR0L
TMR0H
INTCON
T0CON
TRISA
Timer0 Register Low Byte
Timer0 Register High Byte
xxxx xxxx uuuu uuuu
0000 0000 0000 0000
0000 000x 0000 000u
1111 1111 1111 1111
1111 1111 1111 1111
GIE/GIEH PEIE/GIEL TMR0IE INT0IE
RBIE
PSA
TMR0IF INT0IF
T0PS2 T0PS1
RBIF
TMR0ON
T016BIT
T0CS
T0SE
T0PS0
(1)
(1)
TRISA7
TRISA6
PORTA Data Direction Register
Legend: x= unknown, u= unchanged. Shaded cells are not used by Timer0.
Note 1: RA6 and RA7 are enabled as I/O pins depending on the oscillator mode selected in Configuration Word 1H.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 137
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 138
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Register 12-1 details the Timer1 Control register. This
register controls the operating mode of the Timer1
module and contains the Timer1 Oscillator Enable bit
(T1OSCEN). Timer1 can be enabled or disabled by
setting or clearing control bit, TMR1ON (T1CON<0>).
12.0 TIMER1 MODULE
The Timer1 timer/counter module has the following
features:
• 16-bit timer/counter
(two 8-bit registers; TMR1H and TMR1L)
The Timer1 oscillator can be used as a secondary clock
source in power-managed modes. When the T1RUN
bit is set, the Timer1 oscillator provides the system
clock. If the Fail-Safe Clock Monitor is enabled and the
Timer1 oscillator fails while providing the system clock,
polling the T1RUN bit will indicate whether the clock is
being provided by the Timer1 oscillator or another
source.
• Readable and writable (both registers)
• Internal or external clock select
• Interrupt-on-overflow from FFFFh to 0000h
• Reset from CCP module Special Event Trigger
• Status of system clock operation
Figure 12-1 is a simplified block diagram of the Timer1
module.
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.
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 7
bit 0
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
bit 7
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
bit 6
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 (External Clock):
1= Do not synchronize external clock input
0= Synchronize external clock input
When TMR1CS = 0 (Internal Clock):
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
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 139
PIC18F2331/2431/4331/4431
When TMR1CS = 0, Timer1 increments every instruc-
12.1 Timer1 Operation
tion cycle. When TMR1CS = 1, Timer1 increments on
every rising edge of the external clock input or the
Timer1 oscillator, if enabled.
Timer1 can operate in one of these modes:
• As a timer
• As a synchronous counter
• As an asynchronous counter
When the Timer1 oscillator is enabled (T1OSCEN is
set), the RC1/T1OSI/CCP2/FLTA and RC0/T1OSO/
T1CKI pins become inputs. That is, the
TRISC1:TRISC0 value is ignored and the pins are read
as ‘0’.
The operating mode is determined by the Timer1 Clock
Select bit, TMR1CS (T1CON<1>).
Timer1 also has an internal “Reset input”. This Reset
can be generated by the CCP module (see
Section 15.4.4 “Special Event Trigger”).
FIGURE 12-1:
TIMER1 BLOCK DIAGRAM
CCP Special Event Trigger
TMR1IF
Overflow
Interrupt
Flag Bit
Synchronized
TMR1
CLR
0
Clock Input
TMR1L
TMR1H
1
TMR1ON
On/Off
T1SYNC
T1OSC
1
T1CKI/T1OSO
T1OSI
T1OSCEN
Enable
Oscillator
Synchronize
det
Prescaler
1, 2, 4, 8
FOSC/4
Internal
Clock
(1)
0
2
Peripheral Clocks
T1CKPS1:T1CKPS0
TMR1CS
Note 1: When enable bit T1OSCEN is cleared, the inverter and feedback resistor are turned off. This eliminates power drain.
FIGURE 12-2:
TIMER1 BLOCK DIAGRAM: 16-BIT READ/WRITE MODE
Data Bus<7:0>
8
TMR1H
8
8
Write TMR1L
Read TMR1L
CCP Special Event Trigger
TMR1IF
Overflow
Interrupt
8
Synchronized
Clock Input
TMR1
0
CLR
TMR1L
Timer1
High Byte
Flag bit
1
TMR1ON
On/Off
T1SYNC
T1OSC
1
T1CKI/T1OSO
Synchronize
Prescaler
1, 2, 4, 8
T1OSCEN
det
FOSC/4
Internal
Clock
Enable
0
(1)
Oscillator
2
T1OSI
Peripheral Clocks
TMR1CS
T1CKPS1:T1CKPS0
Note 1: When enable bit T1OSCEN is cleared, the inverter and feedback resistor are turned off. This eliminates power drain.
DS39616C-page 140
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
12.2 Timer1 Oscillator
12.3 Timer1 Oscillator Layout
Considerations
A crystal oscillator circuit is built-in between pins T1OSI
(input) and T1OSO (amplifier output). It is enabled by
setting control bit, T1OSCEN (T1CON<3>). The oscil-
lator is a low-power oscillator 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.
The Timer1 oscillator for PIC18F2331/2431/4331/4431
devices incorporates an additional low-power feature.
When this option is selected, it allows the oscillator to
automatically reduce its power consumption when the
microcontroller is in Sleep mode. During normal device
operation, the oscillator draws full current. As high
noise environments may cause excessive oscillator
instability in Sleep mode, this option is best suited for
low noise applications, where power conservation is an
important design consideration.
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
The low-power option is enabled by clearing the
T1OSCMX bit (CONFIG3L<5>). By default, the option
is disabled, which results in a more or less constant
current draw for the Timer1 oscillator.
C1
33 pF
PIC18FXXXX
Due to the low-power nature of the oscillator, it may
also be sensitive to rapidly changing signals in close
proximity.
T1OSI
XTAL
32.768 kHz
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.
T1OSO
C2
33 pF
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.
Note:
See the notes with Table 12-1 for additional
information about capacitor selection.
TABLE 12-1: CAPACITOR SELECTION FOR
THE TIMER OSCILLATOR
FIGURE 12-4:
OSCILLATOR CIRCUIT
WITH GROUNDED GUARD
RING
Osc Type
Freq
C1
C2
LP
32 kHz
27 pF(1)
27 pF(1)
VDD
VSS
Note 1: Microchip suggests this value 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.
OSC1
OSC2
3: Since each resonator/crystal has its own
characteristics, the user should consult
the resonator/crystal manufacturer for
RC0
RC1
appropriate
values
of
external
components.
4: Capacitor values are for design guidance
only.
RC2
Note: Not drawn to scale.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 141
PIC18F2331/2431/4331/4431
A write to the high byte of Timer1 must also take place
12.4 Timer1 Interrupt
through the TMR1H Buffer register. 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.
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 Timer1 Interrupt Flag bit, TMR1IF
(PIR1<0>). This interrupt can be enabled/disabled by
setting/clearing Timer1 Interrupt Enable bit, TMR1IE
(PIE1<0>).
The high byte of Timer1 is not directly readable or writ-
able 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.
12.5 Resetting Timer1 Using a CCP
Trigger Output
12.7 Using Timer1 as a Real-Time
Clock (RTC)
If the CCP1 module is configured in Compare mode
to
generate
a
“Special
Event
Trigger”
Adding an external LP oscillator to Timer1 (such as the
one described in Section 12.2 “Timer1 Oscillator”)
gives users the option to include RTC functionality 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.
(CCP1M3:CCP1M0 = 1011), this signal will reset
Timer1 and start an A/D conversion if the A/D module
is enabled (see Section 15.4.4 “Special Event
Trigger” for more information).
Note:
The Special Event Triggers from the
CCP1 module will not set interrupt flag bit,
TMR1IF (PIR1<0>).
Timer1 must be configured for either Timer or Synchro-
nized Counter mode to take advantage of this feature.
If Timer1 is running in Asynchronous Counter mode,
this Reset operation may not work.
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
register 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.
In the event that a write to Timer1 coincides with a
Special Event Trigger from CCP1, the write will take
precedence.
In this mode of operation, the CCPR1H:CCPR1L regis-
ter pair effectively becomes the Period register for
Timer1.
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 BSF instruction. Note that the TMR1L
register is never preloaded or altered; doing so may
introduce cumulative error over many cycles.
12.6 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 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, is valid due to a rollover between reads.
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.
DS39616C-page 142
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
EXAMPLE 12-1:
IMPLEMENTING A REAL-TIME CLOCK USING A TIMER1 INTERRUPT SERVICE
RTCinit
MOVLW
MOVWF
CLRF
0x80
TMR1H
TMR1L
; Preload TMR1 register pair
; for 1 second overflow
MOVLW
MOVWF
CLRF
b’00001111’
T1OSC
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
MOVLW
MOVWF
RETURN
hours
; No, done
; Reset hours to 1
.01
hours
; Done
TABLE 12-2: REGISTERS ASSOCIATED WITH TIMER1 AS A TIMER/COUNTER
Value on
all other
Resets
Value on
POR, BOR
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
INT0IF
RBIF
0000 000x 0000 000u
PIR1
—
—
—
ADIF
ADIE
ADIP
RCIF
RCIE
RCIP
CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
CCP1IP TMR2IP TMR1IP 1111 1111 -111 1111
xxxx xxxx uuuu uuuu
PIE1
TXIE
TXIP
IPR1
TMR1L
Timer1 Register Low Byte
TMR1H Timer1 Register High Byte
T1CON RD16
Legend: x= unknown, u= unchanged, -= unimplemented, read as ‘0’. Shaded cells are not used by the Timer1 module.
xxxx xxxx uuuu uuuu
T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 u0uu uuuu
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 143
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 144
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
13.1 Timer2 Operation
13.0 TIMER2 MODULE
Timer2 can be used as the PWM time base for the
PWM mode of the CCP module. The TMR2 register is
readable and writable and is cleared on any device
Reset. The input clock (FOSC/4) has a prescale option
of 1:1, 1:4 or 1:16, selected by control bits
The Timer2 module has the following features:
• 8-bit Timer register (TMR2)
• 8-bit Period register (PR2)
• Readable and writable (both registers)
• Software programmable prescaler (1:1, 1:4, 1:16)
• Software programmable postscaler (1:1 to 1:16)
• Interrupt on TMR2 match with PR2
T2CKPS1:T2CKPS0 (T2CON<1:0>). The match out-
put of TMR2 goes through a 4-bit postscaler (which
gives a 1:1 to 1:16 scaling inclusive) to generate a
TMR2 interrupt, latched in flag bit, TMR2IF (PIR1<1>).
• SSP module optional use of TMR2 output to
generate clock shift
The prescaler and postscaler counters are cleared
when any of the following occurs:
Timer2 has a control register shown in Register 13-1.
TMR2 can be shut off by clearing control bit, TMR2ON
(T2CON<2>), to minimize power consumption.
Figure 13-1 is a simplified block diagram of the Timer2
module. Register 13-1 shows the Timer2 Control
register. The prescaler and postscaler selection of
Timer2 are controlled by this register.
• A write to the TMR2 register
• A write to the T2CON register
• 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
TOUTPS3
TOUTPS2
TOUTPS1
TOUTPS0
TMR2ON
T2CKPS1
T2CKPS0
bit 7
bit 0
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
bit 7
Unimplemented: Read as ‘0’
bit 6-3
TOUTPS3:TOUTPS0: 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
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 145
PIC18F2331/2431/4331/4431
13.2 Timer2 Interrupt
13.3 Output of TMR2
The Timer2 module has an 8-bit Period register, PR2.
Timer2 increments from 00h until it matches PR2 and
then resets to 00h on the next increment cycle. PR2 is
a readable and writable register. The PR2 register is
initialized to FFh upon Reset.
The output of TMR2 (before the postscaler) is fed to the
Synchronous Serial Port module, which optionally uses
it to generate the shift clock.
FIGURE 13-1:
TIMER2 BLOCK DIAGRAM
Sets Flag
TMR2
bit TMR2IF
(1)
Output
Prescaler
Reset
EQ
FOSC/4
TMR2
1:1, 1:4, 1:16
Postscaler
1:1 to 1:16
2
Comparator
PR2
T2CKPS1:T2CKPS0
4
TOUTPS3:TOUTPS0
Note 1: TMR2 register output can be software selected by the SSP module as a baud clock.
TABLE 13-1: REGISTERS ASSOCIATED WITH TIMER2 AS A TIMER/COUNTER
Value on
all other
Resets
Value on
POR, BOR
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
INT0IF
RBIF
0000 000x 0000 000u
PIR1
PIE1
—
—
—
ADIF
ADIE
ADIP
RCIF
RCIE
RCIP
TMR2IF
TMR1IF -000 0000 -000 0000
TMR1IE -000 0000 -000 0000
TMR1IP -111 1111 -111 1111
0000 0000 0000 0000
TXIE
TXIP
CCP1IE TMR2IE
CCP1IP TMR2IP
IPR1
TMR2
T2CON
PR2
Timer2 Register
—
TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000
Timer2 Period Register 1111 1111 1111 1111
Legend: x= unknown, u= unchanged, -= unimplemented, read as ‘0’. Shaded cells are not used by the Timer2 module.
DS39616C-page 146
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Timer5 is a general purpose timer/counter that incor-
porates additional features for use with the Motion
Feedback Module (see Section 16.0 “Motion Feed-
back Module”). It may also be used as a general
purpose timer or a Special Event Trigger delay timer.
14.0 TIMER5 MODULE
The Timer5 module implements these features:
• 16-bit timer/counter operation
• Synchronous and Asynchronous Counter modes
• Continuous Count and Single-Shot Operating modes
• Four programmable prescaler values (1:1 to 1:8)
• Interrupt generated on period match
• Special Event Trigger Reset function
• Double-buffered registers
When used as a general purpose timer, it can be
configured to generate a delayed Special Event Trigger
(e.g., an ADC Special Event Trigger) using
preprogrammed period delay.
a
Timer5 is controlled through the Timer5 Control register
(T5CON), shown in Register 14-1. The timer can be
enabled or disabled by setting or clearing the control bit
TMR5ON (T5CON<0>).
• Operation during Sleep
• CPU wake-up from Sleep
A block diagram of Timer5 is shown in Figure 14-1.
• Selectable hardware Reset input with a wake-up
feature
REGISTER 14-1: T5CON: TIMER5 CONTROL REGISTER
R/W-0
R/W-0
RESEN(1)
R/W-0
R/W-0
T5PS1
R/W-0
T5PS0
R/W-0
T5SYNC(2)
R/W-0
R/W-0
T5SEN
T5MOD
TMR5CS
TMR5ON
bit 7
bit 0
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
bit 7
T5SEN: Timer5 Sleep Enable bit
1= Timer5 enabled during Sleep
0= Timer5 disabled during Sleep
bit 6
RESEN: Special Event Trigger Reset Enable bit(1)
1= Special Event Trigger Reset disabled
0= Special Event Trigger Reset enabled
bit 5
T5MOD: Timer5 Mode bit
1= Single-Shot mode enabled
0= Continuous Count mode enabled
bit 4-3
T5PS1:T5PS0: Timer5 Input Clock Prescale Select bits
11= 1:8
10= 1:4
01= 1:2
00= 1:1
bit 2
T5SYNC: Timer5 External Clock Input Synchronization Select bit(2)
When TMR5CS = 1:
1= Do not synchronize external clock input
0= Synchronize external clock input
When TMR5CS = 0:
This bit is ignored. Timer5 uses the internal clock when TMR5CS = 0.
bit 1
bit 0
TMR5CS: Timer5 Clock Source Select bit
1= External clock from pin T5CKI
0= Internal clock (TCY)
TMR5ON: Timer5 On bit
1= Timer5 enabled
0= Timer5 disabled
Note 1: These bits are not implemented on PIC18F2331/2431 devices and read as ‘0’.
2: For Timer5 to operate during Sleep mode, T5SYNC must be set.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 147
PIC18F2331/2431/4331/4431
FIGURE 14-1:
TIMER5 BLOCK DIAGRAM (16-BIT READ/WRITE MODE SHOWN)
1
Internal Data Bus
Noise
Filter
1
0
Synchronize
Detect
Prescaler
1, 2, 4, 8
0
T5CKI
FOSC/4
Internal
Clock
2
Sleep Input
TMR5CS
Timer5
On/Off
T5PS1:T5PS0
T5SYNC
TMR5ON
8
8
TMR5H
8
Write TMR5L
Read TMR5L
TMR5
TMR5L
Special Event
Trigger Input
from IC1
8
1
0
TMR5
High Byte
Timer5 Reset
Timer5 Reset
(external)
16
Reset
Logic
Comparator
16
PR5
8
8
PR5L
PR5H
Set TMR5IF
Special
Event
Logic
Special Event
Trigger Output
Timer5 supports three configurations:
14.1 Timer5 Operation
• 16-Bit Synchronous Timer
• 16-Bit Synchronous Counter
• 16-Bit Asynchronous Counter
Timer5 combines two 8-bit registers to function as a
16-bit timer. The TMR5L register is the actual low byte
of the timer; it can be read and written to directly. The
high byte is contained in an unmapped register; it is
read and written to through TMR5H, which serves as
a buffer. Each register increments from 00h to FFh.
In Synchronous Timer configuration, the timer is
clocked by the internal device clock. The optional
Timer5 prescaler divides the input by 2, 4, 8 or not at all
(1:1). The TMR5 register pair increments on Q1.
Clearing TMR5CS (= 0) selects the internal device
clock as the timer sampling clock.
A second register pair, PR5H and PR5L, serves as the
Period register; it sets the maximum count for the
TMR5 register pair. When TMR5 reaches the value of
PR5, the timer rolls over to 00h and sets the TMR5IF
interrupt flag. A simplified block diagram of the Timer5
module is shown in Figure 2-1.
Note:
The Timer5 may be used as a general pur-
pose timer and as the time base resource to
the Motion Feedback Module (Input Capture
or Quadrature Encoder Interface).
DS39616C-page 148
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
In Synchronous Counter mode configuration, the timer
14.2 16-Bit Read/Write and Write Modes
is clocked by the external clock (T5CKI) with the
optional prescaler. The external T5CKI is selected by
setting the TMR5CS bit (TMR5CS = 1); the internal
clock is selected by clearing TMR5CS. The external
clock is synchronized to the internal clock by clearing
the T5SYNC bit. The input on T5CKI is sampled on
every Q2 and Q4 of the internal clock. The low to rise
transition is decoded on three adjacent samples and
the Timer5 is incremented on the next Q1. The T5CKI
minimum pulse-width high and low time must be
greater than TCY/2.
As noted, the actual high byte of the Timer5 register
pair is mapped to TMR5H, which serves as a buffer.
Reading TMR5L will load the contents of the high byte
of the register pair into the TMR5H register. This allows
the user to accurately read all 16 bits of the register pair
without having to determine whether a read of the high
byte, followed by the low byte, is valid due to a rollover
between reads.
Since the actual high byte of the Timer5 register pair is
not directly readable or writable, it must be read and
written to through the Timer5 High Byte Buffer register
(TMR5H). The T5 high byte is updated with the con-
tents of TMR5H when a write occurs to TMR5L. This
allows a user to write all 16 bits to both the high and low
bytes of Timer5 at once. Writes to TMR5H do not clear
the Timer5 prescaler. The prescaler is only cleared on
writes to TMR5L.
In Asynchronous Counter mode configuration, Timer5
is clocked by the external clock (T5CKI) with the
optional prescaler. In this mode, T5CKI is not synchro-
nized to the internal clock. By setting TMR5CS, the
external input clock (T5CKI) can be used as the
counter sampling clock. When T5SYNC is set, the
external clock is not synchronized to the internal device
clock.
14.2.1
16-BIT READ-MODIFY-WRITE
The timer count is not reset automatically when the
module is disabled. The user may write the Counter
register to initialize the counter.
Read-modify-write instructions, like BSF and BCF, will
read the contents of a register, make the appropriate
changes and place the result back into the register. The
write portion of a read-modify-write instruction of
TMR5H will not update the contents of the high byte of
TMR5 until a write of TMR5L takes place. Only then will
the contents of TMR5H be placed into the high byte of
TMR5.
Note:
The Timer5 module does NOT prevent
writes to the PR5 registers (PR5H:PR5L)
while the timer is enabled. Writing to PR5
while the timer is enabled may result in
unexpected period match events.
14.1.1
CONTINUOUS COUNT AND
SINGLE-SHOT OPERATION
14.3 Timer5 Prescaler
The Timer5 clock input (either TCY or the external clock)
may be divided by using the Timer5 programmable
prescaler. The prescaler control bits, T5PS1:T5PS0
(T5CON<4:3>), select a prescale factor of 2, 4, 8 or no
prescale.
Timer5 has two operating modes: Continuous Count
and Single-Shot.
Continuous Count mode is selected by clearing the
T5MOD control bit (= 0). In this mode, the Timer5 time
base will start incrementing according to the prescaler
settings until a TMR5/PR5 match occurs, or until TMR5
rolls over (FFFFh to 0000h). The TMR5IF interrupt flag
is set, the TMR5 register is reset on the following input
clock edge and the timer continues to count for as long
as the TMR5ON bit remains set.
The Timer5 prescaler is cleared by any of the following:
• A write to the Timer5 register
• Disabling Timer5 (TMR5ON = 0)
• A device Reset such as Master Clear, POR or
BOR
Single-Shot mode is selected by setting T5MOD (= 1).
In this mode, the Timer5 time base begins to increment
according to the prescaler settings until a TMR5/PR5
match occurs. This causes the TMR5IF interrupt flag to
be set, the TMR5 register pair to be cleared on the
following input clock edge and the TMR5ON bit to be
cleared by the hardware to halt the timer.
Note:
Writing to the T5CON register does not
clear the Timer5.
The Timer5 time base can only start incrementing in
Single-Shot mode under two conditions:
1. Timer5 is enabled (TMR5ON is set), or
2. Timer5 is disabled and a Special Event Trigger
Reset is present on the Timer5 Reset input. (See
Section 14.7 “Timer5 Special Event Trigger
Reset Input” for additional information).
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 149
PIC18F2331/2431/4331/4431
14.7.1
WAKE-UP ON IC1 EDGE
14.4 Noise Filter
The Timer5 Special Event Trigger Reset input can act
as a Timer5 wake-up and a start-up pulse. Timer5 must
be in Single-Shot mode and disabled (TMR5ON = 0).
An active edge on the CAP1 input pin will set TMR5ON.
The timer is subsequently incremented on the next fol-
lowing clock according to the prescaler and the Timer5
clock settings. A subsequent hardware time-out (such
as TMR5/PR5 match) will clear the TMR5ON bit and
stop the timer.
The Timer5 module includes an optional input noise
filter, designed to reduce spurious signals in noisy
operating environments. The filter ensures that the input
is not permitted to change until a stable value has been
registered for three consecutive sampling clock cycles.
The noise filter is part of the input filter network associ-
ated with the Motion Feedback Module (see
Section 16.0 “Motion Feedback Module”). All of the
filters are controlled using the Digital Filter Control
(DFLTCON) register (Register 16-3). The Timer5 filter
can be individually enabled or disabled by setting or
clearing the FLT4EN bit (DFLTCON<6>). It is disabled
on all Brown-out Resets.
14.7.2
DELAYED ACTION EVENT TRIGGER
An active edge on CAP1 can also be used to initiate
some later action delayed by the Timer5 time base. In
this case, Timer5 increments as before after being
triggered. When the hardware time-out occurs, the
Special Event Trigger output is generated and used to
trigger another action, such as an A/D conversion. This
allows a given hardware action to be referenced from a
capture edge on CAP1 and delayed by the timer.
For additional information, refer to Section 16.3
“Noise Filters” in the Motion Feedback Module.
14.5 Timer5 Interrupt
Timer5 has the ability to generate an interrupt on a
period match. When the PR5 register is loaded with a
new period value (00FFh), the Timer5 time base incre-
ments until its value is equal to the value of PR5. When
a match occurs, the Timer5 interrupt is generated on
the rising edge of Q4; TMR5IF is set on the next TCY.
The event timing for the delayed action event trigger is
discussed further in Section 16.1 “Input Capture”.
14.7.3
SPECIAL EVENT TRIGGER RESET
WHILE TIMER5 IS INCREMENTING
The interrupt latency (i.e., the time elapsed from the
moment Timer5 rolls over until TMR5IF is set) will not
exceed 1 TCY. When the Timer5 clock input is prescaled
and a TMR5/PR5 match occurs, the interrupt will be
generated on the first Q4 rising edge after TMR5 resets.
In the event that a bus write to Timer5 coincides with a
Special Event Trigger Reset, the bus write will always
take precedence over the Special Event Trigger Reset.
14.8 Operation in Sleep Mode
When Timer5 is configured for asynchronous operation,
it will continue to increment each timer clock (or prescale
multiple of clocks). Executing the SLEEPinstruction will
either stop the timer or let the timer continue, depending
on the setting of the Timer5 Sleep Enable bit, T5SEN. If
T5SEN is set (= 1), the timer continues to run when the
SLEEPinstruction is executed and the external clock is
selected (TMR5CS = 1). If T5SEN is cleared, the timer
stops when a SLEEPinstruction is executed, regardless
of the state of the TMR5CS bit.
14.6 Timer5 Special Event Trigger
Output
A Timer5 Special Event Trigger is generated on a
TMR5/PR5 match. The Special Event Trigger is
generated on the falling edge of Q3.
Timer5 must be configured for either Synchronous
mode (Counter or Timer) to take advantage of the
Special Event Trigger feature. If Timer5 is running in
Asynchronous Counter mode, the Special Event
Trigger may not work and should not be used.
To summarize, Timer5 will continue to increment when
a SLEEPinstruction is executed only if all of these bits
are set:
14.7 Timer5 Special Event Trigger
Reset Input
• TMR5ON
• T5SEN
In addition to the Special Event Trigger output, Timer5
has a Special Event Trigger Reset input that may be
used with Input Capture Channel 1 (IC1) of the Motion
Feedback Module. To use the Special Event Trigger
Reset, the Capture 1 Control register, CAP1CON, must
be configured for one of the Special Event Trigger
modes (CAP1M3:CAP1M0 = 1110 or 1111). The
Special Event Trigger Reset can be disabled by setting
the RESEN control bit (T5CON<6>).
• TMR5CS
• T5SYNC
14.8.1
INTERRUPT DETECT IN SLEEP MODE
When configured as described above, Timer5 will
continue to increment on each rising edge on T5CKI
while in Sleep mode. When a TMR5/PR5 match occurs,
an interrupt is generated which can wake the part.
The Special Event Trigger Reset resets the Timer5 time
base. This reset occurs in either Continuous Count or
Single-Shot modes.
DS39616C-page 150
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 14-1: REGISTERS ASSOCIATED WITH TIMER5
Value on
all other
Resets
Value on:
POR, BOR
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTCON
IPR3
GIE/GIEH PEIE/GIEL TMR0IE
INT0IE
PTIP
PTIE
PTIF
RBIE
TMR0IF
INT0IF
IC1IP
IC1IE
IC1IF
RBIF
0000 000x 0000 000u
—
—
—
—
—
—
—
—
—
IC3DRIP IC2QEIP
IC3DRIE IC2QEIE
IC3DRIF IC2QEIF
TMR5IP ---1 1111 ---1 1111
TMR5IE ---0 0000 ---0 0000
TMR5IF ---0 0000 ---0 0000
xxxx xxxx uuuu uuuu
PIE3
PIR3
TMR5H
TMR5L
PR5H
Timer5 Register High Byte
TImer5 Register Low Byte
xxxx xxxx uuuu uuuu
Timer5 Period Register High Byte
Timer5 Period Register Low Byte
1111 1111 1111 1111
PR5L
1111 1111 1111 1111
T5CON
CAP1CON
DFLTCON
Legend:
T5SEN
—
RESEN
CAP1REN
FLT4EN
T5MOD
—
T5PS1
—
T5PS0 T5SYNC TMR5CS TMR5ON 0000 0000 0000 0000
CAP1M3 CAP1M2 CAP1M1 CAP1M0 -0-- 0000 -0-0 0000
—
FLT3EN FLT2EN FLT1EN FLTCK2 FLTCK1 FLTCK0 -000 0000 -000 0000
x= unknown, u= unchanged, -= unimplemented. Shaded cells are not used by the Timer5 module.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 151
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 152
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 15-1: CCP MODE – TIMER
15.0 CAPTURE/COMPARE/PWM
RESOURCES
(CCP) MODULES
CCP Mode
Timer Resources
The CCP (Capture/Compare/PWM) module contains a
16-bit register that can operate as a 16-bit Capture reg-
ister, a 16-bit Compare register or a PWM Master/Slave
Duty Cycle register. Table 15-1 shows the timer
resources required for each of the CCP module modes.
Capture
Compare
PWM
Timer1
Timer1
Timer2
The operation of CCP1 is identical to that of CCP2, with
the exception of the Special Event Trigger. Therefore,
operation of a CCP module is described with respect to
CCP1, except where noted.
15.2 CCP2 Module
Capture/Compare/PWM Register 2 (CCPR2) is com-
prised of two 8-bit registers: CCPR2L (low byte) and
CCPR2H (high byte). The CCP2CON register controls
the operation of CCP2. All are readable and writable.
15.1 CCP1 Module
Capture/Compare/PWM Register
1
(CCPR1) is
comprised of two 8-bit registers: CCPR1L (low byte)
and CCPR1H (high byte). The CCP1CON register
controls the operation of CCP1. All are readable and
writable.
REGISTER 15-1: CCPxCON: CCPx CONTROL REGISTER
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 7
bit 0
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
bit 7-6
bit 5-4
Unimplemented: Read as ‘0’
DCxB1:DCxB0: PWM Duty Cycle bit 1 and bit 0
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 upper eight bits
(DCxB9:DCxB2) of the duty cycle are found in CCPRxL.
bit 3-0
CCPxM3:CCPxM0: CCPx Mode Select bits
0000= Capture/Compare/PWM disabled (resets CCPx 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 CCPx pin low; on compare match, force CCPx pin high (CCPxIF bit is set)
1001= Compare mode; initialize CCPx pin high; on compare match, force CCPx pin low (CCPxIF bit is set)
1010= Compare mode; generate software interrupt on compare match (CCPxIF bit is set, CCPx pin is
unaffected)
1011= Compare mode; Special Event Trigger (CCPxIF bit is set)
11xx= PWM mode
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 153
PIC18F2331/2431/4331/4431
15.3.3
SOFTWARE INTERRUPT
15.3 Capture Mode
When the Capture mode is changed, a false capture
interrupt may be generated. The user should keep bit,
CCP1IE (PIE1<2>), clear to avoid false interrupts and
should clear the flag bit, CCP1IF, following any such
change in operating mode.
In Capture mode, CCPR1H:CCPR1L captures the
16-bit value of the TMR1 register when an event
occurs on pin RC2/CCP1. An event is defined as
one of the following:
• every falling edge
• every rising edge
15.3.4
CCP PRESCALER
• every 4th rising edge
• every 16th rising edge
There are four prescaler settings specified by bits
CCP1M3:CCP1M0. Whenever the CCP module is
turned off, or the CCP module is not in Capture mode,
the prescaler counter is cleared. This means that any
Reset will clear the prescaler counter.
The event is selected by control bits, CCP1M3:CCP1M0
(CCP1CON<3:0>). When a capture is made, the
interrupt request flag bit, CCP1IF (PIR1<2>), is set; it
must be cleared in software. If another capture occurs
before the value in register CCPR1 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
a non-zero prescaler. Example 15-1 shows the recom-
mended method for switching between capture
prescalers. This example also clears the prescaler
counter and will not generate the “false” interrupt.
15.3.1
CCP PIN CONFIGURATION
In Capture mode, the RC2/CCP1 pin should be
configured as an input by setting the TRISC<2> bit.
Note:
If the RC2/CCP1 pin is configured as an
output, a write to the port can cause a
capture condition.
EXAMPLE 15-1:
CHANGING BETWEEN
CAPTURE PRESCALERS
CLRF
CCP1CON, F
; Turn CCP module off
; Load WREG with the
; new prescaler mode
; value and CCP ON
; Load CCP1CON with
; this value
MOVLW
NEW_CAPT_PS
15.3.2
TIMER1 MODE SELECTION
Timer1 must be running in Timer mode or Synchro-
nized Counter mode to be used with the capture
feature. In Asynchronous Counter mode, the capture
operation may not work.
MOVWF
CCP1CON
FIGURE 15-1:
CAPTURE MODE OPERATION BLOCK DIAGRAM
Set Flag bit CCP1IF
CCPR1H
CCPR1L
Prescaler
÷ 1, 4, 16
TMR1
Enable
CCP1 Pin
and
TMR1H
TMR1L
Edge Detect
CCP1CON<3:0>
Qs
Set Flag bit CCP2IF
CCPR2H
CCPR2L
TMR1L
Prescaler
÷ 1, 4, 16
TMR1
Enable
CCP2 Pin
and
Edge Detect
TMR1H
CCP2CON<3:0>
Qs
DS39616C-page 154
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
15.4.2
TIMER1 MODE SELECTION
15.4 Compare Mode
Timer1 must be running in Timer mode or Synchro-
nized 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 CCPR1 (CCPR2) register
value is constantly compared against the TMR1
register pair value. When a match occurs, the RC2/
CCP1 (RC1/CCP2) pin:
• is driven high
15.4.3
SOFTWARE INTERRUPT MODE
• is driven low
When generate software interrupt is chosen, the CCP1
pin is not affected. Only a CCP interrupt is generated (if
enabled).
• toggles output (high-to-low or low-to-high)
• remains unchanged (interrupt only)
The action on the pin is based on the value of control
bits, CCP1M3:CCP1M0 (CCP2M3:CCP2M0). At the
same time, interrupt flag bit CCP1IF (CCP2IF) is set.
15.4.4
SPECIAL EVENT TRIGGER
In this mode, an internal hardware trigger is generated
which may be used to initiate an action.
15.4.1
CCP PIN CONFIGURATION
The Special Event Trigger output of CCP1 resets the
TMR1 register pair. This allows the CCPR1 register to
effectively be a 16-bit programmable period register for
Timer1.
The user must configure the CCP1 pin as an output by
clearing the appropriate TRISC bit.
Note:
Clearing the CCP1CON register will force
the RC2/CCP1 compare output latch to
the default low level. This is not the
PORTC I/O data latch.
The Special Event Trigger output of CCP2 resets the
TMR1 register pair. Additionally, the CCP2 Special
Event Trigger will start an A/D conversion if the A/D
module is enabled.
Note:
The Special Event Trigger from the CCP2
module will not set the Timer1 interrupt
flag bit.
FIGURE 15-2:
COMPARE MODE OPERATION BLOCK DIAGRAM
Special Event Trigger will:
Reset Timer1, but not set Timer1 interrupt flag bit
and set bit, GO/DONE (ADCON0<1>), which starts an A/D conversion (CCP2 only)
Special Event Trigger
Set Flag bit CCP1IF
CCPR1H CCPR1L
Comparator
Q
S
R
Output
Logic
Match
RC2/CCP1 Pin
TRISC<2>
Output Enable
CCP1CON<3:0>
Mode Select
TMR1H TMR1L
Special Event Trigger
Set Flag bit CCP2IF
Match
Q
S
R
Output
Logic
Comparator
RC1/CCP2 Pin
TRISC<1>
Output Enable
CCPR2H CCPR2L
CCP2CON<3:0>
Mode Select
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 155
PIC18F2331/2431/4331/4431
TABLE 15-2: REGISTERS ASSOCIATED WITH CAPTURE, COMPARE AND TIMER1
Value on
all other
Resets
Value on
POR, BOR
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
INT0IF
RBIF
0000 000x 0000 000u
—
—
—
ADIF
ADIE
ADIP
RCIF
RCIE
RCIP
CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
CCP1IP TMR2IP TMR1IP -111 1111 -111 1111
1111 1111 1111 1111
PIE1
TXIE
TXIP
IPR1
TRISC
TMR1L
TMR1H
T1CON
CCPR1L
PORTC Data Direction Register
Timer1 Register Low Byte
Timer1 Register High Byte
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
RD16
T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu
Capture/Compare/PWM Register 1 Low Byte
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
CCPR1H Capture/Compare/PWM Register 1 High Byte
CCP1CON
CCPR2L
—
—
DC1B1
DC1B0
CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 --00 0000
xxxx xxxx uuuu uuuu
Capture/Compare/PWM Register 2 Low Byte
CCPR2H Capture/Compare/PWM Register 2 High Byte
xxxx xxxx uuuu uuuu
CCP2CON
PIR2
—
—
—
—
—
DC2B1
—
DC2B0
EEIF
CCP2M3 CCP2M2 CCP2M1 CCP2M0 --00 0000 --00 0000
OSCFIF
OSCFIE
OSCFIP
—
—
—
LVDIF
LVDIE
LVDIP
—
—
—
CCP2IF 0--0 -0-0 0--0 -0-0
CCP2IE 0--0 -0-0 0--0 -0-0
CCP2IP 1--1 -1-1 1--1 -1-1
PIE2
—
EEIE
EEIP
IPR2
—
Legend:
x= unknown, u= unchanged, -= unimplemented, read as ‘0’. Shaded cells are not used by Capture, Compare and Timer1.
DS39616C-page 156
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
15.5.1
PWM PERIOD
15.5 PWM Mode
The PWM period is specified by writing to the PR2
register. The PWM period can be calculated using the
following equation:
In Pulse-Width Modulation (PWM) mode, the CCP1 pin
produces up to a 10-bit resolution PWM output. Since
the CCP1 pin is multiplexed with the PORTC data latch,
the TRISC<2> bit must be cleared to make the CCP1
pin an output.
EQUATION 15-1:
PWM Period = [(PR2) + 1] • 4 • TOSC •
(TMR2 Prescale Value)
Note:
Clearing the CCP1CON register will force
the CCP1 PWM output latch to the default
low level. This is not the 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
CCP1 module in PWM mode.
• TMR2 is cleared
For a step-by-step procedure on how to set up the
CCP1 module for PWM operation, see Section 15.5.3
“Setup for PWM Operation”.
• 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
FIGURE 15-3:
SIMPLIFIED PWM BLOCK
DIAGRAM
Note: The Timer2 postscaler (see Section 13.0
“Timer2 Module”) is not used in the deter-
mination of the PWM frequency. The
postscaler could be used to have a servo
update rate at a different frequency than
the PWM output.
CCP1CON<5:4>
Duty Cycle Registers
CCPR1L
15.5.2
PWM DUTY CYCLE
CCPR1H (Slave)
Comparator
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:
R
S
Q
RC2/CCP1
(Note 1)
TMR2
TRISC<2>
Comparator
PR2
Clear Timer,
CCP1 pin and
latch D.C.
EQUATION 15-2:
PWM Duty Cycle = (CCPR1L:CCP1CON<5:4>) •
TOSC • (TMR2 Prescale Value)
Note 1: 8-bit timer is concatenated with 2-bit internal
Q clock or 2 bits of the prescaler to create
10-bit time base.
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.
A PWM output (Figure 15-4) has a time base
(period) and a time that the output is 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
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 157
PIC18F2331/2431/4331/4431
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 operation.
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:
15.5.3
SETUP FOR PWM OPERATION
The following steps should be taken when configuring
the CCP1 module for PWM operation:
1. Set the PWM period by writing to the PR2 register.
2. Set the PWM duty cycle by writing to the CCPR1L
register and CCP1CON<5:4> bits.
3. Make the CCP1 pin an output by clearing the
TRISC<2> bit.
EQUATION 15-3:
4. Set the TMR2 prescale value and enable Timer2
by writing to T2CON.
FOSC
FPWM
⎛
⎝
⎞
⎠
log
5. Configure the CCP1 module for PWM operation.
PWM Resolution (max) =
bits
log(2)
Note:
If the PWM duty cycle value is longer than
the PWM period, the CCP1 pin will not be
cleared.
TABLE 15-3: 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)
TABLE 15-4: REGISTERS ASSOCIATED WITH PWM AND TIMER2
Value on
all other
Resets
Value on
POR, BOR
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
INT0IF
RBIF
0000 000x 0000 000u
—
—
—
ADIF
ADIE
ADIP
RCIF
RCIE
RCIP
TMR2IF
TMR1IF -000 0000 -000 0000
TMR1IE -000 0000 -000 0000
TMR1IP -111 1111 -111 1111
1111 1111 1111 1111
PIE1
TXIE
TXIP
CCP1IE TMR2IE
CCP1IP TMR2IP
IPR1
TRISC
TMR2
PR2
PORTC Data Direction Register
Timer2 Register
0000 0000 0000 0000
Timer2 Period Register
1111 1111 1111 1111
T2CON
CCPR1L
—
TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000
Capture/Compare/PWM Register 1 Low Byte
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
CCPR1H Capture/Compare/PWM Register 1 High Byte
CCP1CON
CCPR2L
—
—
DC1B1
DC1B0
CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 --00 0000
xxxx xxxx uuuu uuuu
Capture/Compare/PWM Register 2 Low Byte
CCPR2H Capture/Compare/PWM Register 2 High Byte
CCP2CON DC2B1 DC2B0
xxxx xxxx uuuu uuuu
—
—
CCP2M3 CCP2M2 CCP2M1 CCP2M0 --00 0000 --00 0000
Legend: x= unknown, u= unchanged, -= unimplemented, read as ‘0’. Shaded cells are not used by PWM and Timer2.
DS39616C-page 158
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Many of the features for the IC and QEI submodules
16.0 MOTION FEEDBACK MODULE
are fully programmable, creating a flexible peripheral
structure that can accommodate a wide range of
in-system uses. An overview of the available features
is presented in Table 16-1. A simplified block diagram
of the entire Motion Feedback Module is shown in
Figure 16-1.
The Motion Feedback Module (MFM) is a special
purpose peripheral designed for motion feedback
applications. Together with the Power Control PWM
(PCPWM) module (see Section 17.0 “Power Control
PWM Module”), it provides a variety of control
solutions for a wide range of electric motors.
Note:
Because the same input pins are common
to the IC and QEI submodules, only one of
these two submodules may be used at any
given time. If both modules are on, the QEI
submodule will take precedence.
The module actually consists of two hardware
submodules:
• Input Capture (IC)
•
Quadrature Encoder Interface (QEI)
Together with Timer5 (see Section 14.0 “Timer5
Module”), these modules provide a number of
options for motion and control applications.
TABLE 16-1: SUMMARY OF MOTION FEEDBACK MODULE FEATURES
Submodule
Mode(s)
Features
Timer
Function
IC (3x)
• Synchronous
• Input Capture
• Flexible Input Capture modes
• Available Prescaler
TMR5 • 3x Input Capture (edge
capture, pulse-width, period
measurement, capture on
change)
• Selectable Time Base Reset
• Special Event Trigger for ADC
Sampling/Conversion or optional
TMR5 Reset feature (CAP1 only)
• Wake-up from Sleep function
• Selectable Interrupt Frequency
• Optional Noise Filter
• Special Event Triggers the
A/D Conversion on the CAP1
Input
QEI
QEI
• Detect Position
16-Bit • Position Measurement
Position • Direction of Rotation Status
Counter
• Detect Direction of Rotation
• Large Bandwidth (FCY/16)
• Optional Noise Filter
Velocity
Measurement
• 2x and 4x Update modes
• Velocity Event Postscaler
• Counter Overflow Flag for Low
Rotation Speed
TMR5 • Precise Velocity Measurement
• Direction of Rotation Status
• Utilizes Input Capture 1 Logic
(IC1)
• High and Low Velocity Support
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 159
PIC18F2331/2431/4331/4431
FIGURE 16-1:
MOTION FEEDBACK MODULE BLOCK DIAGRAM
TMR5IF
Special Event Trigger Reset
Timer Reset
TMR5
Reset
Control
Special Event Trigger Output
Timer5
TMR5<15:0>
8
Filter
TCY
T5CKI
3x Input Capture Logic
TMR5<15:0>
IC3IF
Filter
Filter
IC3
IC2
IC1
8
8
CAP3/QEB
CAP2/QEA
IC2IF
IC1IF
Special Event Trigger Reset
8
Filter
CAP1/INDX
TCY
Clock
Divider
8
Postscaler
QEB
Velocity Event
Timer Reset
8
Direction
QEA
Position Counter
Clock
QEIF
QEI
Control
Logic
CHGIF
INDX
8
QEI Logic
CHGIF
IC3IF
IC3DRIF
QEI
Mode
Decoder
8
QEIF
IC2IF
IC2QEIF
DS39616C-page 160
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Input Channel 1 (IC1) includes a Special Event
Trigger that can be configured for use in Velocity Mea-
16.1 Input Capture
The Input Capture (IC) submodule implements the
following features:
surement mode. Its block diagram is shown in
Figure 16-2. IC2 and IC3 are similar, but lack the
Special Event Trigger features or additional velocity
measurement logic. A representative block diagram is
shown in Figure 16-3. Please note that the time base
is Timer5.
• Three channels of independent input capture
(16-bits/channel) on the CAP1, CAP2 and CAP3
pins
• Edge-Trigger, Period or Pulse-Width
Measurement Operating modes for each channel
• Programmable prescaler on every input capture
channel
• Special Event Trigger output (IC1 only)
• Selectable noise filters on each capture input
FIGURE 16-2:
INPUT CAPTURE BLOCK DIAGRAM FOR IC1
CAP1 Pin
and
Mode
Select
Prescaler
1, 4, 16
Clock
Noise
Filter
CAP1BUF/VELR(1)
3
4
FLTCK<2:0>
Q Clocks
CAP1M<3:0>
IC1IF
Reset
IC1_TR
TMR5
Reset
Control
Special
Event Trigger
Reset
Clock/
Reset/
Interrupt
Decode
Logic
Timer5 Logic
1
CAP1BUF_clk
First Event
Reset
MUX
0
Timer5 Reset
Timer
Reset
Control
velcap(2)
VELM
Q Clocks
CAP1M<3:0>
Note 1: CAP1BUF register is reconfigured as VELR register when QEI mode is active.
2: QEI generated velocity pulses, vel_out, are downsampled to produce this velocity capture signal.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 161
PIC18F2331/2431/4331/4431
FIGURE 16-3:
INPUT CAPTURE BLOCK DIAGRAM FOR IC2 AND IC3
Capture
Clock
CAPxBUF(1,2,3)
CAP2/3 Pin
and
Prescaler
Noise
Filter
Mode
1, 4, 16
Select
TMR5
Enable
3
4
TMR5
CAP1M<3:0>(1)
FLTCK<2:0>
Q Clocks
ICxIF(1)
Capture Clock/
Reset/
CAPxBUF_clk(1)
Interrupt
Decode
Logic
TMR5 Reset
Timer
Reset
Reset
Control
Q Clocks CAPxM<3:0>(1)
CAPxREN(2)
Note 1: IC2 and IC3 are denoted as x = 2 and 3.
2: CAP2BUF is enabled as POSCNT when QEI mode is active.
3: CAP3BUF is enabled as MAXCNT when QEI mode is active.
DS39616C-page 162
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
The three input capture channels are controlled
through the Input Capture Control registers,
CAP1CON, CAP2CON and CAP3CON. Each channel
is configured independently with its dedicated register.
The implementation of the registers is identical except
for the Special Event Trigger (see Section 16.1.8
“Special Event Trigger (CAP1 Only)”). The typical
Capture Control register is shown in Register 16-1.
Note:
Throughout this section, references to
registers and bit names that may be asso-
ciated with a specific capture channel will
be referred to generically by the use of the
term ‘x’ in place of the channel number.
For example, ‘CAPxREN’ may refer to the
Capture Reset Enable bit in CAP1CON,
CAP2CON or CAP3CON.
REGISTER 16-1: CAPxCON: INPUT CAPTURE x CONTROL REGISTER
U-0
—
R/W-0
U-0
—
U-0
—
R/W-0
R/W-0
R/W-0
R/W-0
CAPxREN
CAPxM3
CAPxM2
CAPxM1
CAPxM0
bit 7
bit 0
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
bit 7
bit 6
Unimplemented: Read as ‘0’
CAPxREN: Time Base Reset Enable bit
1= Enabled
0= Disable selected time base Reset on capture
bit 5-4
bit 3-0
Unimplemented: Read as ‘0’
CAPxM3:CAPxM0: Input Capture x (ICx) Mode Select bits
1111= Special Event Trigger mode; the trigger occurs on every rising edge on CAP1 input(1)
1110= Special Event Trigger mode; the trigger occurs on every falling edge on CAP1 input(1)
1101= Unused
1100= Unused
1011= Unused
1010= Unused
1001= Unused
1000= Capture on every CAPx input state change
0111= Pulse-Width Measurement mode, every rising to falling edge
0110= Pulse-Width Measurement mode, every falling to rising edge
0101= Frequency Measurement mode, every rising edge
0100= Capture mode, every 16th rising edge
0011= Capture mode, every 4th rising edge
0010= Capture mode, every rising edge
0001= Capture mode, every falling edge
0000= Input Capture x (ICx) off
Note 1: Special Event Trigger is only available on CAP1. For CAP2 and CAP3, this configuration is unused.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 163
PIC18F2331/2431/4331/4431
When in Counter mode, the counter must be
configured as the synchronous counter only
(T5SYNC = 0). When configured in Asynchronous
mode, the IC module will not work properly.
16.1.1
EDGE CAPTURE MODE
In this mode, the value of the time base is captured
either on every rising edge, every falling edge, every
4th rising edge, or every 16th rising edge. The edge
present on the input capture pin (CAP1, CAP2 or
CAP3) is sampled by the synchronizing latch. The
signal is used to load the Input Capture Buffer (ICxBUF
register) on the following Q1 clock (see Figure 16-4).
Consequently, Timer5 is either reset to ‘0’ (Q1
immediately following the capture event) or left free
running, depending on the setting of the Capture Reset
Enable bit, CAPxREN, in the CAPxCON register.
Note 1: Input capture prescalers are reset
(cleared) when the input capture module
is disabled (CAPxM = 0000).
2: When the Input Capture mode is changed
without first disabling the module and
entering the new Input Capture mode, a
false interrupt (or Special Event Trigger
on IC1) may be generated. The user
should either: (1) disable the input
capture before entering another mode, or
(2) disable IC interrupts to avoid false
interrupts during IC mode changes.
Note:
On the first capture edge following the
setting of the Input Capture mode (i.e.,
MOVWF CAP1CON), Timer5 contents are
always captured into the corresponding
Input Capture Buffer (i.e., CAPxBUF).
Timer5 can optionally be reset; however,
this is dependent on the setting of the
Capture Reset Enable bit, CAPxREN (see
Figure 16-4).
3: During IC mode changes, the prescaler
count will not be cleared, therefore the
first capture in the new IC mode may be
from the non-zero prescaler.
FIGURE 16-4:
EDGE CAPTURE MODE TIMING
Q1Q2 Q3 Q4 Q1
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 Q1Q2 Q3 Q4
Q2 Q3 Q4
OSC
(1)
0012
0013
0014
0015
0000
0001
0016
0002
0000
0001
0002
TMR5
(2)
CAP1 Pin
ABCD
0003
0002
Note 5
(3)
CAP1BUF
(4)
TMR5 Reset
Instruction
Execution
MOVWF CAP1CON
BCF CAP1CON, CAP1REN
Note 1: TMR5 is a synchronous time base input to the input capture, prescaler = 1:1. It increments on Q1 rising edge.
2: IC1 is configured in Edge Capture mode (CAP1M3:CAP1M0 = 0010) with the time base reset upon edge capture
(CAP1REN = 1) and no noise filter.
3: TMR5 value is latched by CAP1BUF on TCY. In the event that a write to TMR5 coincides with an input capture event,
the write will always take precedence. All Input Capture Buffers, CAP1BUF, CAP2BUF and CAP3BUF, are updated
with the incremented value of the time base on the next TCY clock edge when the capture event takes place (see Note
4 when Reset occurs).
4: TMR5 Reset is normally an asynchronous Reset signal to TMR5. When used with the input capture, it is active
immediately after the time base value is captured.
5: TMR5 Reset pulse is disabled by clearing the CAP1REN bit (e.g., BCF CAP1CON, CAP1REN).
DS39616C-page 164
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Timer5 is always reset on the edge when the
measurement is first initiated. For example, when the
measurement is based on the falling to rising edge,
Timer5 is first reset on the falling edge and the timer
value is captured on the rising edge thereafter. Upon
entry into the Pulse-Width Measurement mode, the
very first edge detected on the CAPx pin is always
captured. The TMR5 value is reset on the first active
edge (see Figure 16-5).
16.1.2
PERIOD MEASUREMENT MODE
The Period Measurement mode is selected by setting
CAPxM3:CAPxM0 = 0101. In this mode, the value of
Timer5 is latched into the CAPxBUF register on the
rising edge of the input capture trigger and Timer5 is
subsequently reset to 0000h (optional by setting
CAPxREN = 1) on the next TCY (see capture and Reset
relationship in Figure 16-4).
16.1.3
PULSE-WIDTH MEASUREMENT
MODE
The Pulse-Width Measurement mode can be configured
for two different edge sequences, such that the pulse
width is based on either the falling to rising edge of the
CAPx input pin (CAPxM3:CAPxM0 = 0110), or on the
rising to falling edge (CAPxM3:CAPxM0 = 0111).
FIGURE 16-5:
PULSE-WIDTH MEASUREMENT MODE 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 Q1Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
(1)
0012
0013
0014
0015
0000
0015
0001
0002
0000
0001
0001
0002
0002
TMR5
(2)
CAP1 Pin
(3)
CAP1BUF
(4,5)
TMR5 Reset
Instruction
Execution
MOVWF CAP1CON
(2)
Note 1: TMR5 is a synchronous time base input to the input capture, prescaler = 1:1. It increments on every Q1 rising edge.
2: IC1 is configured in Pulse-Width Measurement mode (CAP1M3:CAP1M0 = 0111, rising to falling pulse-width
measurement). No noise filter on CAP1 input is used. MOVWFinstruction loads CAP1CON when W = 0111.
3: TMR5 value is latched by CAP1BUF on TCY rising edge. In the event that a write to TMR5 coincides with an input cap-
ture event, the write will always take precedence. All Input Capture Buffers, CAP1BUF, CAP2BUF and CAP3BUF, are
updated with the incremented value of the time base on the next TCY clock edge when the capture event takes place
(see Note 4 when Reset occurs).
4: TMR5 Reset is normally an asynchronous Reset signal to TMR5. When used in Pulse-Width Measurement mode, it
is always present on the edge that first initiates the pulse-width measurement (i.e., when configured in the rising to
falling Pulse-Width Measurement mode), it is active on each rising edge detected. In the falling to rising Pulse-Width
Measurement mode, it is active on each falling edge detected.
5: TMR5 Reset pulse is activated on the capture edge. CAP1REN bit has no bearing in this mode.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 165
PIC18F2331/2431/4331/4431
16.1.3.1
Pulse-Width Measurement Timing
16.1.4
INPUT CAPTURE ON STATE
CHANGE
Pulse-width measurement accuracy can only be
ensured when the pulse-width high and low present on
the CAPx input exceeds one TCY clock cycle. The
limitations depend on the mode selected:
When CAPxM3:CAPxM0 = 1000, the value is captured
on every signal change on the CAPx input. If all three
capture channels are configured in this mode, the three
input captures can be used as the Hall effect sensor
state transition detector. The value of Timer5 can be
captured, Timer5 reset and the interrupt generated.
Any change on CAP1, CAP2 or CAP3 is detected and
the associated time base count is captured.
• When CAPxM3:CAPxM0 = 0110(rising to falling
edge delay), the CAPx input high pulse width
(TCCH) must exceed TCY + 10 ns.
• When CAPxM3:CAPxM0 = 0111(falling to rising
edge delay), the CAPx input low pulse width
(TCCL) must exceed TCY + 10 ns.
For position and velocity measurement in this mode,
the timer can be optionally reset (see Section 16.1.6
“Timer5 Reset” for Reset options).
Note 1: The Period Measurement mode will
produce valid results upon sampling of
the second rising edge of the input
capture. CAPxBUF values latched during
the first active edge after initialization are
invalid.
2: The Pulse-Width Measurement mode will
latch the value of the timer upon sampling
of the first input signal edge by the input
capture.
FIGURE 16-6:
INPUT CAPTURE ON STATE CHANGE (HALL EFFECT SENSOR MODE)
1
0
1
0
1
1
0
1
0
1
0
0
CAP1
CAP2
CAP3
1
0
0
0
1
1
0FFFh
0000h
Time Base(1)
CAP1BUF(2)
CAP2BUF(2)
CAP3BUF(2)
Time Base Reset(1)
Note 1: TMR5 can be selected as the time base for input capture. Time base can be optionally reset when the Capture Reset
Enable bit is set (CAPxREN = 1).
2: Detailed CAPxBUF event timing (all modes reflect same capture and Reset timing) is shown in Figure 16-4. There
are six commutation BLDC Hall effect sensor states shown. The other two remaining states (i.e., 000h and 111h)are
invalid in the normal operation. They remain to be decoded by the CPU firmware in BLDC motor application.
DS39616C-page 166
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
16.1.5
ENTERING INPUT CAPTURE MODE
AND CAPTURE TIMING
16.1.6
TIMER5 RESET
Every input capture trigger can optionally reset
(TMR5). The Capture Reset Enable bit, CAPxREN,
gates the automatic Reset of the time base of the cap-
ture event with this enable Reset signal. All capture
events reset the selected timer when CAPxREN is set.
Resets are disabled when CAPxREN is cleared (see
Figure 16-4, Figure 16-5 and Figure 16-6).
The following is a summary of functional operation
upon entering any of the Input Capture modes:
1. After the module is configured for one of the
Capture modes by setting the Capture Mode
Select bits (CAPxM3:CAPxM0), the first
detected edge captures the Timer5 value and
stores it in the CAPxBUF register. The timer is
then reset (depending on the setting of
CAPxREN bit) and starts to increment according
to its settings (see Figure 16-4, Figure 16-5 and
Figure 16-6).
Note:
The CAPxREN bit has no effect in
Pulse-Width Measurement mode.
16.1.7
IC INTERRUPTS
There are four operating modes for which the IC
module can generate an interrupt and set one of the
Interrupt Capture Flag bits (IC1IF, IC2QEIF or
IC3DRIF). The interrupt flag that is set depends on the
channel in which the event occurs. The modes are:
2. On all edges, the capture logic performs the
following:
a) Input Capture mode is decoded and the
active edge is identified.
b) The CAPxREN bit is checked to determine
whether Timer5 is reset or not.
• Edge Capture
(CAPxM3:CAPxM0 = 0001, 0010, 0011or 0100)
c) On every active edge, the Timer5 value is
recorded in the Input Capture Buffer
(CAPxBUF).
• Period Measurement Event
(CAPxM3:CAPxM0 = 0101)
• Pulse-Width Measurement Event
d) Reset Timer5 after capturing the value of
the timer when the CAPxREN bit is
enabled. Timer5 is reset on every active
capture edge in this case.
(CAPxM3:CAPxM0 = 0110or 0111)
• State Change Event (CAPxM3:CAPxM0 = 1000)
Note:
The Special Event Trigger is generated only
in the Special Event Trigger mode on the
CAP1 input (CAP1M2:CAP1M0 = 1110
and 1111). IC1IF interrupt is not set in this
mode.
e) On all continuing capture edge events,
repeat steps (a) through (d) until the opera-
tional mode is terminated, either by user
firmware, POR or BOR.
The timing of interrupt and Special Event Trigger
events is shown in Figure 16-7. Any active edge is
detected on the rising edge of Q2 and propagated on
the rising edge of Q4 rising edge. If an active edge
happens to occur any later than this (on the falling edge
of Q2, for example), then it will be recognized on the
next Q2 rising edge.
f) The timer value is not affected when switch-
ing into and out of various Input Capture
modes.
FIGURE 16-7:
CAPx INTERRUPTS AND IC1 SPECIAL EVENT TRIGGER
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
OSC
CAP1 Pin
IC1IF
TMR5 Reset
TMR5
0001
XXXX
0000
TMR5ON(1)
Note 1: Timer5 is only reset and enabled (assuming TMR5ON = 0and T5MOD = 1) when the Special Event Trigger Reset is
enabled for the Timer5 Reset input. TMR5ON bit is asserted and Timer5 is reset on the Q1 rising edge following the
event capture. With the Special Event Trigger Reset disabled, Timer5 cannot be reset by the Special Event Trigger
Reset on the CAP1 input. In order for the Special Event Trigger Reset to work as the Reset trigger to Timer5, IC1 must
be configured in the Special Event Trigger mode (CAP1M<3:0> = 1110or 1111).
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 167
PIC18F2331/2431/4331/4431
16.1.8
SPECIAL EVENT TRIGGER
(CAP1 ONLY)
16.1.9
OPERATING MODES SUMMARY
Table 16-3 shows a summary of the input capture
configuration when used in conjunction with the TMR5
timer resource.
The Special Event Trigger mode of IC1
(CAP1M3:CAP1M0 = 1110 or 1111) enables the
Special Event Trigger signal. The trigger signal can be
used as the Special Event Trigger Reset input to TMR5,
resetting the timer when the specific event happens on
IC1. The events are summarized in Table 16-2.
16.1.10 OTHER OPERATING MODES
Although the IC and QEI submodules are mutually
exclusive, the IC can be reconfigured to work with the
QEI module to perform specific functions. In effect, the
QEI “borrows” hardware from the IC to perform these
operations.
TABLE 16-2: SPECIAL EVENT TRIGGER
CAP1M3:
Description
CAP1M0
For velocity measurement, the QEI uses dedicated
hardware in channel IC1. The CAP1BUF registers are
remapped, becoming the VELR registers. Its operation
and use are described in Section 16.2.6 “Velocity
Measurement”.
1110
The trigger occurs on every falling
edge on the CAP1 input.
1111
The trigger occurs on every rising
edge on the CAP1 input.
While in QEI mode, the CAP2BUF and CAP3BUF reg-
isters of channel IC2 and IC3 are used for position
determination. They are remapped as the POSCNT
and MAXCNT Buffer registers, respectively.
TABLE 16-3: INPUT CAPTURE TIME BASE RESET SUMMARY
Reset Timer
Pin
CAPxM
Mode
Timer
Description
on Capture
CAP1 0001-0100 Edge Capture
TMR5
optional(1)
Simple Edge Capture mode (includes a
selectable prescaler).
0101
Period Measurement
TMR5
TMR5
optional(1)
always
Captures Timer5 on period boundaries.
Captures Timer5 on pulse boundaries.
0110-0111 Pulse-Width
Measurement
1000
Input Capture on State
Change
TMR5
TMR5
optional(1)
optional(2)
Captures Timer5 on state change.
1110-1111 Special Event Trigger
Used as a Special Event Trigger to be
used with the Timer5 or other peripheral
modules.
(rising or falling edge)
CAP2 0001-0100 Edge Capture
TMR5
optional(1)
Simple Edge Capture mode (includes a
selectable prescaler).
0101
Period Measurement
TMR5
TMR5
optional(1)
always
Captures Timer5 on period boundaries.
Captures Timer5 on pulse boundaries.
0110-0111 Pulse-Width
Measurement
1000
Input Capture on State
Change
CAP3 0001-0100 Edge Capture
TMR5
TMR5
optional(1)
optional(1)
Captures Timer5 on state change.
Simple Edge Capture mode (includes a
selectable prescaler).
0101
Period Measurement
TMR5
TMR5
optional(1)
always
Captures Timer5 on period boundaries.
Captures Timer5 on pulse boundaries.
0110-0111 Pulse-Width
Measurement
1000
Input Capture on State
Change
TMR5
optional(1)
Captures Timer5 on state change.
Note 1: Timer5 may be reset on capture events only when CAPxREN = 1.
2: Trigger mode will not reset Timer5 unless RESEN = 0in the T5CON register.
DS39616C-page 168
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The QEI control logic detects the leading edge on the
16.2 Quadrature Encoder Interface
QEA or QEB phase input pins and generates the count
pulse, which is sent to the position counter logic. It also
samples the index input signal (INDX) and generates
the direction of the rotation signal (up/down) and the
velocity event signals.
The Quadrature Encoder Interface (QEI) decodes
speed and motion sensor information. It can be used in
any application that uses a quadrature encoder for
feedback. The interface implements these features:
• Three QEI inputs: two phase signals (QEA and
QEB) and one index signal (INDX)
The position counter acts as an integrator for tracking
distance traveled. The QEA and QEB input edges
serve as the stimulus to create the input clock which
advances the Position Counter register (POSCNT).
The register is incremented on either the QEA input
edge, or the QEA and QEB input edges, depending on
the operating mode. It is reset either by a rollover on
match to the Period register, MAXCNT, or on the
external index pulse input signal (INDX). An interrupt is
generated on a reset of POSCNT if the position counter
interrupt is enabled.
• Direction of movement detection with a direction
change interrupt (IC3DRIF)
• 16-bit up/down position counter
• Standard and High-Precision Position Tracking
modes
• Two Position Update modes (x2 and x4)
• Velocity measurement with a programmable
postscaler for high-speed velocity measurement
• Position counter interrupt (IC2QEIF in the PIR3
register)
The velocity postscaler down samples the velocity
pulses used to increment the velocity counter by a
specified ratio. It essentially divides down the number
of velocity pulses to one output per so many inputs,
preserving the pulse width in the process.
• Velocity control interrupt (IC1IF in the PIR3
register)
The QEI submodule has three main components: the
QEI control logic block, the position counter and
velocity postscaler.
A simplified block-diagram of the QEI module is shown
in Figure 16-8.
FIGURE 16-8:
QEI BLOCK DIAGRAM
QEI Module
Direction Change
Set CHGIF
Reset Timer5
Velocity Capture
8
Timer Reset
Velocity Event
Postscaler
Set UP/DOWN
Direction
Clock
8
Filter
Filter
QEB
QEA
INDX
CAP2BUF/POSCNT
Comparator
CAP3/QEB
CAP2/QEA
Reset on Match
Set IC2QEIF
8
CAP3BUF/MAXCNT
QEI
Control
Logic
Filter
Position Counter
CAP1/INDX
8
8
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 169
PIC18F2331/2431/4331/4431
The operation of the QEI is controlled by the QEICON
Configuration register (see Register 16-2).
16.2.1
QEI CONFIGURATION
The QEI module shares its input pins with the Input
Capture (IC) module. The inputs are mutually
exclusive; only the IC module or the QEI module (but
not both) can be enabled at one time. Also, because
the IC and QEI are multiplexed to the same input pins,
the programmable noise filters can be dedicated to one
module only.
Note:
In the event that both QEI and IC are
enabled, QEI will take precedence and IC
will remain disabled.
REGISTER 16-2: QEICON: QUADRATURE ENCODER INTERFACE CONTROL REGISTER
R/W-0
VELM
R/W-0
QERR(1)
R-0
R/W-0
QEIM2(2,3)
R/W-0
QEIM1(2,3)
R/W-0
QEIM0(2,3)
R/W-0
R/W-0
UP/DOWN
PDEC1
PDEC0
bit 7
bit 0
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
bit 7
VELM: Velocity Mode bit
1= Velocity mode disabled
0= Velocity mode enabled
bit 6
QERR: QEI Error bit(1)
1= Position counter overflow or underflow(4)
0= No overflow or underflow
bit 5
UP/DOWN: Direction of Rotation Status bit
1= Forward
0=Reverse
bit 4-2
QEIM2:QEIM0: QEI Mode bits(2,3)
111= Unused
110= QEI enabled in 4x Update mode; position counter reset on period match (POSCNT = MAXCNT)
101= QEI enabled in 4x Update mode; INDX resets the position counter
100= Unused
010= QEI enabled in 2x Update mode; position counter reset on period match (POSCNT = MAXCNT)
001= QEI enabled in 2x Update mode; INDX resets the position counter
000= QEI off
bit 1-0
PDEC1:PDEC0: Velocity Pulse Reduction Ratio bits
11= 1:64
10= 1:16
01= 1:4
00= 1:1
Note 1: QEI must be enabled and in Index mode.
2: QEI mode select must be cleared (= 000) to enable CAP1, CAP2 or CAP3 inputs. If QEI and IC modules
are both enabled, QEI will take precedence.
3: Enabling one of the QEI operating modes remaps the IC Buffer registers, CAP1BUFH, CAP1BUFL,
CAP2BUFH, CAP2BUFL, CAP3BUFH and CAP3BUFL, as the VELRH, VELRL, POSCNTH, POSCNTL,
MAXCNTH and MAXCNTL registers (respectively) for the QEI.
4: QERR bit must be cleared in software.
DS39616C-page 170
Preliminary
© 2007 Microchip Technology Inc.
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16.2.2
QEI MODES
16.2.3
QEI OPERATION
Position measurement resolution depends on how
often the Position Counter register, POSCNT, is
incremented. There are two QEI Update modes to
measure the rotor’s position: QEI x2 and QEI x4.
The Position Counter register pair (POSCNTH:
POSCNTL) acts as an integrator, whose value is propor-
tional to the position of the sensor rotor that corresponds
to the number of active edges detected. POSCNT can
either increment or decrement, depending on a number
of selectable factors which are decoded by the QEI logic
block. These include the Count mode selected, the
phase relationship of QEA to QEB (“lead/lag”), the
direction of rotation and if a Reset event occurs. The
logic is detailed in the sections that follow.
TABLE 16-4: QEI MODES
QEIM2:
QEIM0
Mode/
Reset
Description
QEI disabled.(1)
000
001
—
x2 update/ Two clocks per QEA pulse.
index pulse INDX resets POSCNT.
16.2.3.1
Edge and Phase Detect
In the first step, the active edges of QEA and QEB are
detected, and the phase relationship between them is
determined. The position counter is changed based on
the selected QEI mode.
010
x2 update/ Two clocks per QEA pulse.
period
match
POSCNT reset by the period
match (MAXCNT).
011
100
101
—
—
Unused.
Unused.
In QEI x2 Update mode, the position counter
increments or decrements on every QEA edge based
on the phase relationship of the QEA and QEB signals.
x4 update/ Four clocks per QEA and
index pulse QEB pulse pair.
INDX resets POSCNT.
In QEI x4 Update mode, the position counter
increments or decrements on every QEA and QEB
edge based on the phase relationship of the QEA and
QEB signals. For example, if QEA leads QEB, the
position counter is incremented by ‘1’. If QEB lags
QEA, the position counter is decremented by ‘1’.
110
x4 update/ Four clocks per QEA and
period
match
QEB pulse pair.
POSCNT reset by the period
match (MAXCNT).
111
—
Unused.
16.2.3.2
Direction of Count
Note 1: QEI module is disabled. The position
counter and the velocity measurement
functions are fully disabled in this mode.
The QEI control logic generates a signal that sets
the UP/DOWN bit (QEICON<5>); this in turn
determines the direction of the count. When QEA
leads QEB, UP/DOWN is set (= 1) and the position
counter increments on every active edge. When
QEA lags QEB, UP/DOWN is cleared and the
position counter decrements on every active edge.
16.2.2.1
QEI x2 Update Mode
QEI x2 Update mode is selected by setting the QEI
Mode Select bits (QEIM2:QEIM0) to ‘001’ or ‘010’. In
this mode, the QEI logic detects every edge on the
QEA input only. Every rising and falling edge on the
QEA signal clocks the position counter.
TABLE 16-5: DIRECTION OF ROTATION
Previous Signal
The position counter can be reset by either an input on
the INDX pin (QEIM2:QEIM0 = 001), or by a period
match, even when the POSCNT register pair equals
MAXCNT (QEIM2:QEIM0 = 010).
Detected
Current
Signal
Detected
Pos.
Rising Falling
Cntrl.(1)
QEA QEB QEA QEB
16.2.2.2
QEI x4 Update Mode
QEA Rising
QEA Falling
QEB Rising
QEB Falling
x
INC
DEC
DEC
INC
QEI x4 Update mode provides for a finer resolution of
the rotor position, since the counter increments or
decrements more frequently for each QEA/QEB input
pulse pair than in QEI x2 mode. This mode is selected
by setting the QEI mode select bits to ‘101’ or ‘110’. In
QEI x4, the phase measurement is made on the rising
and the falling edges of both QEA and QEB inputs. The
position counter is clocked on every QEA and QEB
edge.
x
x
x
x
x
x
x
INC
DEC
INC
DEC
Like QEI x2 mode, the position counter can be reset by
an input on the pin (QEIM2:QEIM0 = 101), or by the
period match event (QEIM2:QEIM0 = 010).
Note 1: When UP/DOWN = 1, the position counter
is incremented; when UP/DOWN = 0, the
position counter is decremented.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 171
PIC18F2331/2431/4331/4431
16.2.3.3
Reset and Update Events
16.2.4
QEI INTERRUPTS
The position counter will continue to increment or dec-
rement until one of the following events takes place.
The type of event and the direction of rotation when it
happens determines if a register Reset or update
occurs.
The position counter interrupt occurs and the interrupt
flag (IC2QEIF) is set, based on the following events:
• A POSCNT/MAXCNT period match event
(QEIM2:QEIM0 = 010or 110)
• A POSCNT rollover (FFFFh to 0000h) in Period
mode only (QEIM2:QEIM0 = 010or 110)
1. An index pulse is detected on the INDX input
(QEIM2:QEIM0 = 001).
• An index pulse detected on INDX
If the encoder is traveling in the forward direc-
tion, POSCNT is reset (00h) on the next clock
edge after the index marker, INDX, has been
detected. The position counter resets on the
QEA or QEB edge once the INDX rising edge
has been detected.
The interrupt timing diagrams for IC2QEIF are shown in
Figure 16-10 and Figure 16-11.
When the direction has changed, the direction change
interrupt flag (IC3DRIF) is set on the following TCY
clock (see Figure 16-10).
If the position counter rolls over in Index mode, the
QERR bit will be set.
If the encoder is traveling in the reverse direc-
tion, the value in the MAXCNT register is loaded
into POSCNT on the next quadrature pulse
edge (QEA or QEB) after the falling edge on
INDX has been detected.
16.2.5
QEI SAMPLE TIMING
The quadrature input signals, QEA and QEB, may vary
in quadrature frequency. The minimum quadrature
input period, TQEI, is 16 TCY.
2. A POSTCNT/MAXCNT period match occurs
(QEIM2:QEIM0 = 010).
The position count rate, FPOS, is directly proportional to
the rotor’s RPM, line count D and QEI Update mode (x2
versus x4); that is,
If the encoder is traveling in the forward direc-
tion, POSCNT is reset (00h) on the next clock
edge when POSCNT = MAXCNT. An interrupt
event is triggered on the next TCY after the Reset
(see Figure 16-10)
EQUATION 16-1:
4D • RPM
FPOS =
If the encoder is traveling in the reverse
direction and the value of POSCNT reaches
00h, POSCNT is loaded with the contents of the
MAXCNT register on the next clock edge. An
interrupt event is triggered on the next TCY after
the load operation (see Figure 16-10).
60
Note:
The number of incremental lines in the
position encoder is typically set at D = 1024
and the QEI Update mode = x4.
The value of the position counter is not affected during
QEI mode changes, nor when the QEI is disabled
altogether.
The maximum position count rate (i.e., x4 QEI
Update mode, D = 1024) with FCY = 10 MIPS is equal
to 2.5 MHz, which corresponds to FQEI of 625 kHz.
Figure 16-9 shows QEA and QEB quadrature input
timing when sampled by the noise filter.
DS39616C-page 172
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 16-9:
QEI INPUTS WHEN SAMPLED BY THE FILTER (DIVIDE RATIO = 1:1)
TCY
QEA Pin
(1)
TQEI = 16 TCY
QEB Pin
QEA Input
TGD = 3 TCY
QEB Input
Note 1: The module design allows a quadrature frequency of up to FQEI = FCY/16.
FIGURE 16-10:
QEI MODULE RESET TIMING ON PERIOD MATCH
Forward
Reverse
QEA
QEB
+1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
Count (+/-)
(1)
POSCNT
MAXCNT
MAXCNT=1527
Note 6
Note 2
IC2QEIF
Note 2
UP/DOWN
(3)
(3)
Q4
Q4
(5)
(4)
Q1
Q1
Position
Counter Load
IC3DRIF
(5)
Q1
Note 1: POSCNT register is shown in QEI x4 Update mode (POSCNT increments on every rising and every falling edge of
QEA and QEB input signals). Asynchronous external QEA and QEB inputs are synchronized to TCY clock by the
input sampling FF in the noise filter (see Figure 16-14).
2: When POSCNT = MAXCNT, POSCNT is reset to ‘0’ on the next QEA rising edge. POSCNT is set to MAXCNT when
POSCNT = 0(when decrementing), which occurs on the next QEA falling edge.
3: IC2QEIF is generated on Q4 rising edge.
4: Position counter is loaded with ‘0’ (which is a rollover event in this case) on POSCNT = MAXCNT.
5: Position counter is loaded with MAXCNT value (1527h) on underflow.
6: IC2QEIF must be cleared in software.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 173
PIC18F2331/2431/4331/4431
FIGURE 16-11:
QEI MODULE RESET TIMING WITH THE INDEX INPUT
Forward
Note 2
Reverse
Note 2
QEA
QEB
-1 -1 -1 -1
-1 -1 -1 -1
+1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
Count (+/-)
(1)
POSCNT
MAXCNT
INDX
MAXCNT = 1527
Note 6
IC2QEIF
UP/DOWN
(3)
(3)
Q4
Q4
(5)
(4)
Q1
Q1
Position
Counter Load
Note 1: POSCNT register is shown in QEI x4 Update mode (POSCNT increments on every rising and every falling edge of
QEA and QEB input signals).
2: When INDX Reset pulse is detected, POSCNT is reset to ‘0’ on the next QEA or QEB edge. POSCNT is set to
MAXCNT when POSCNT = 0(when decrementing), which occurs on the next QEA or QEB edge. Similar Reset
sequence occurs for the reverse direction except that the INDX signal is recognized on its falling edge. The Reset
is generated on the next QEA or QEB edge.
3: IC2QEIF is enabled for one TCY clock cycle.
4: Position counter is loaded with ‘0000h’ (i.e., Reset) on the next QEA or QEB edge when INDX is high.
5: Position counter is loaded with MAXCNT value (e.g., 1527h) on the next QEA or QEB edge following the INDX
falling edge input signal detect).
6: IC2QEIF must be cleared in software.
DS39616C-page 174
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
16.2.6
VELOCITY MEASUREMENT
16.2.6.1
Velocity Event Timing
The velocity pulse generator, in conjunction with the
IC1 and the synchronous TMR5 (in synchronous
operation), provides a method for high accuracy speed
measurements at both low and high mechanical motor
speeds. The Velocity mode is enabled when the VELM
bit is cleared (= 0) and QEI is set to one of its operating
modes (see Table 16-6).
The event pulses are reduced by a fixed ratio by the
velocity pulse divider. The divider is useful for
high-speed measurements where the velocity events
happen frequently. By producing a single output pulse
for a given number of input event pulses, the counter
can track larger pulse counts (i.e., distance travelled)
for a given time interval. Time is measured by utilizing
the TMR5 time base.
To optimize register space, the Input Capture
Channel 1 (IC1) is used to capture TMR5 counter
values. Input Capture Buffer register, CAP1BUF, is
redefined in Velocity Measurement mode, VELM = 0,
as the Velocity Register Buffer (VELRH, VELRL).
Each velocity pulse serves as a capture pulse. With the
TMR5 in Synchronous Timer mode, the value of TMR5
is captured on every output pulse of the postscaler. The
counter is subsequently reset to ‘0’. TMR5 is reset
upon a capture event.
TABLE 16-6: VELOCITY PULSES
Figure 16-13 shows the velocity measurement timing
diagram.
QEIM<2:0>
Velocity Event Mode
001
010
x2 Velocity Event mode. The velocity
pulse is generated on every QEA edge.
101
110
x4 Velocity Event mode. The velocity
pulse is generated on every QEA and
QEB active edge.
FIGURE 16-12:
VELOCITY MEASUREMENT BLOCK DIAGRAM
TMR5 Reset
Reset
Logic
QEI
Control
Logic
Clock
TMR5
16
TCY
Velocity Mode
Velocity Capture
IC1
Velocity Event
Postscaler
(VELR Register)
CAP3/QEB
QEB
QEA
INDX
Direction
Clock
CAP2/QEA
CAP1/INDX
Position
Counter
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 175
PIC18F2331/2431/4331/4431
FIGURE 16-13:
VELOCITY MEASUREMENT TIMING(1)
Forward
Reverse
QEA
QEB
vel_out
velcap
(2)
TMR5
(2)
VELR
Old Value
1529
1537
(3)
cnt_reset
Q1
Q1
Q1
(4)
IC1IF
CAP1REN
Instr.
Execution
MOVWF QEICON(5)
BCFPIE2,IC1IE
BSFPIE2,IC1IE
BCF T5CON,VELM
Note 1: Timing shown is for QEIM<2:0> = 101, 110or 111(x4 Update mode enabled) and the velocity postscaler divide ratio
is set to divide by 4 (PDEC<1:0> = 01).
2: VELR register latches the TMR5 count on the “velcap” capture pulse. Timer5 must be set to the Synchronous Timer or
Counter mode. In this example, it is set to the Synchronous Timer mode, where the TMR5 prescaler divide ratio = 1
(i.e., Timer5 clock = TCY).
3: The TMR5 counter is reset on the next Q1 clock cycle following the “velcap” pulse. TMR5 value is unaffected when
the Velocity Measurement mode is first enabled (VELM = 0). The velocity postscaler values must be reconfigured to
their previous settings when re-entering Velocity Measurement mode. While making speed measurements of very
slow rotational speeds (e.g., servo-controller applications), the Velocity Measurement mode may not provide
sufficient precision. The Pulse-Width Measurement mode may have to be used to provide the additional precision.
In this case, the input pulse is measured on the CAP1 input pin.
4: IC1IF interrupt is enabled by setting IC1IE as follows: BSF PIE2, IC1IE. Assume IC1E bit is placed in PIE2
Peripheral Interrupt Enable register in the target device. The actual IC1IF bit is written on Q2 rising edge.
5: Post decimation value is changed from PDEC = 01(decimate by 4) to PDEC = 00(decimate by 1).
16.2.6.2
Velocity Postscaler
16.2.6.3
CAP1REN in Velocity Mode
The velocity event pulse (velcap, see Figure 16-12)
serves as the TMR5 capture trigger to IC1 while in the
Velocity mode. The number of velocity events are
reduced by the velocity postscaler before they are used
as the input capture clock. The velocity event reduction
ratio can be set with the PDEC1:PDEC0 control bits
(QEICON<1:0>) to 1:4, 1:16, 1:64 or no reduction (1:1).
The TMR5 value can be reset (TMR5 register
pair = 0000h) on a velocity event capture by setting
the CAP1REN bit (CAP1CON<6>). When CAP1REN
is cleared, the TMR5 time base will not be reset on
any velocity event capture pulse. The VELR register
pair, however, will continue to be updated with the
current TMR5 value.
The velocity postscaler settings are automatically
reloaded from their previous values as the Velocity
mode is re-enabled.
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Preliminary
© 2007 Microchip Technology Inc.
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programmed by the FLTCK2:FLTCK0 Configuration
bits. TCY is used as the clock reference to the clock
divider block.
16.3 Noise Filters
The Motion Feedback Module includes three noise
rejection filters on CAP1/INDX, CAP2/QEA and
CAP3/QEB. The filter block also includes a fourth filter
for the T5CKI pin. They are intended to help reduce
spurious noise spikes which may cause the input sig-
nals to become corrupted at the inputs. The filter
ensures that the input signals are not permitted to
change until a stable value has been registered for
three consecutive sampling clock cycles.
The noise filters can either be added or removed from
the input capture or QEI signal path by setting or
clearing the appropriate FLTxEN bit, respectively. Each
capture channel provides for individual enable control
of the filter output. The FLT4EN bit enables or disabled
the noise filter available on T5CKI input in the Timer5
module.
The filter network for all channels is disabled on
Power-on and Brown-out Resets, as the DFLTCON
register is cleared on Resets. The operation of the filter
is shown in the timing diagram in Figure 16-14.
The filters are controlled using the Digital Filter Control
(DFLTCON) register (see Register 16-3). The filters
can be individually enabled or disabled by setting or
clearing the corresponding FLTxEN bit in the
DFLTCON register. The sampling frequency, which
must be the same for all three noise filters, can be
REGISTER 16-3: DFLTCON: DIGITAL FILTER CONTROL REGISTER
U-0
—
R/W-0
R/W-0
FLT3EN(1)
R/W-0
FLT2EN(1)
R/W-0
FLT1EN(1)
R/W-0
R/W-0
R/W-0
FLT4EN
FLTCK2
FLTCK1
FLTCK0
bit 7
bit 0
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
bit 7
bit 6
Unimplemented: Read as ‘0’
FLT4EN: Noise Filter Output Enable bit, T5CKI Input
1= Enabled
0= Disabled
bit 5
FLT3EN: Noise Filter Output Enable bit, CAP3/QEB Input(1)
1= Enabled
0= Disabled
bit 4
FLT2EN: Noise Filter Output Enable bit, CAP2/QEA Input(1)
1= Enabled
0= Disabled
bit 3
FLT1EN: Noise Filter Output Enable bit, CAP1/INDX Input(1)
1= Enabled
0= Disabled
bit 2-0
FLTCK<2:0>: Noise Filter Clock Divider Ratio bits
111= Unused
110= 1:128
101= 1:64
100= 1:32
011= 1:16
010= 1:4
001= 1:2
000= 1:1
Note 1: Noise filter output enables are functional in both QEI and IC Operating modes.
Note: The Noise Filter is intended for random high-frequency filtering and not continuous high-frequency filtering.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 177
PIC18F2331/2431/4331/4431
FIGURE 16-14:
NOISE FILTER TIMING DIAGRAM (CLOCK DIVIDER = 1:1)
TQEI = 16 TCY
TCY
(3)
(3)
Noise Glitch
Noise Glitch
(1)
CAP1/INDX Pin
(input to filter)
(2)
CAP1/INDX Input
(output from filter)
TGD = 3TCY
Note 1: Only CAP1/INDX pin input is shown for simplicity. Similar event timing occurs on CAP2/QEA and CAP3/QEB pins.
2: Noise filtering occurs in shaded portions of CAP1 input.
3: Filter’s group delay: TGD = 3 TCY.
16.4 IC and QEI Shared Interrupts
16.5 Operation in Sleep Mode
The IC and QEI submodules can each generate three
distinct interrupt signals; however, they share the use
of the same three interrupt flags in register PIR3. The
meaning of a particular interrupt flag at any given time
depends on which module is active at the time the
interrupt is set. The meaning of the flags in context are
summarized in Table 16-7.
16.5.1
3x INPUT CAPTURE IN SLEEP
MODE
Since the input capture can operate only when its time
base is configured in a Synchronous mode, the input
capture will not capture any events. This is because the
device’s internal clock has been stopped and any inter-
nal timers in Synchronous modes will not increment.
The prescaler will continue to count the events (not
synchronized).
When the IC submodule is active, the three flags (IC1IF,
IC2QEIF and IC3DRIF) function as interrupt-on-capture
event flags for their respective input capture channels.
The channel must be configured for one of the events
that will generate an interrupt (see Section 16.1.7 “IC
Interrupts” for more information).
When the specified capture event occurs, the CAPx
interrupt will be set. The Capture Buffer register will be
updated upon wake-up from sleep to the current TMR5
value. If the CAPx interrupt is enabled, the device will
wake-up from Sleep. This effectively enables all input
capture channels to be used as the external interrupts.
When the QEI is enabled, the IC1IF interrupt flag
indicates an interrupt caused by
a
velocity
measurement event, usually an update of the VELR
register. The IC2QEIF interrupt indicates that a position
measurement event has occurred. IC3DRIF indicates
that a direction change has been detected.
16.5.2
QEI IN SLEEP MODE
All QEI functions are halted in Sleep mode.
TABLE 16-7: MEANING OF IC AND QEI
INTERRUPT FLAGS
Meaning
Interrupt
Flag
IC Mode
QEI Mode
IC1IF
IC1 Capture Event Velocity Register Update
IC2QEIF IC2 Capture Event Position Measurement
Update
IC3DRIF IC3 Capture Event
Direction Change
DS39616C-page 178
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 16-8: REGISTERS ASSOCIATED WITH THE MOTION FEEDBACK MODULE
Value on
Value on:
POR, BOR
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
all other
Resets
INTCON
IPR3
GIE/GIEH PEIE/GIEL
TMR0IE
INT0IE
PTIP
PTIE
PTIF
RBIE
TMR0IF
IC2QEIP
IC2QEIE
IC2QEIF
INT0IF
IC1IP
IC1IE
IC1IF
RBIF
0000 000x 0000 000u
—
—
—
—
—
—
—
—
—
IC3DRIP
IC3DRIE
IC3DRIF
TMR5IP ---1 1111 ---1 1111
TMR5IE ---0 0000 ---0 0000
TMR5IF ---0 0000 ---0 0000
xxxx xxxx uuuu uuuu
PIE3
PIR3
TMR5H
TMR5L
PR5H
PR5L
Timer5 Register High Byte
Timer5 Register Low Byte
xxxx xxxx uuuu uuuu
Timer5 Period Register High Byte
Timer5 Period Register Low Byte
1111 1111 1111 1111
1111 1111 1111 1111
T5CON
T5SEN
RESEN
T5MOD
T5PS1
T5PS0
T5SYNC
TMR5CS TMR5ON 0000 0000 0000 0000
(1)
CAP1BUFH/ Capture 1 Register High Byte/Velocity Register High Byte
VELRH
xxxx xxxx uuuu uuuu
(1)
CAP1BUFL/ Capture 1 Register Low Byte/Velocity Register Low Byte
VELRL
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
(1)
CAP2BUFH/ Capture 2 Register High Byte/QEI Position Counter Register High Byte
POSCNTH
(1)
CAP2BUFL/ Capture 2 Register Low Byte/QEI Position Counter Register Low Byte
POSCNTL
(1)
CAP3BUFH/ Capture 3 Register High Byte/QEI Max. Count Limit Register High Byte
MAXCNTH
(1)
CAP3BUFL/ Capture 3 Register Low Byte/QEI Max. Count Limit Register Low Byte
MAXCNTL
CAP1CON
CAP2CON
CAP3CON
DFLTCON
QEICON
—
—
CAP1REN
CAP2REN
CAP3REN
FLT4EN
—
—
—
—
CAP1M3
CAP2M3
CAP3M3
FLT1EN
QEIM1
CAP1M2
CAP1M1 CAP1M0 -0-- 0000 -0-- 0000
CAP2M1 CAP2M0 -0-- 0000 -0-- 0000
CAP3M1 CAP3M0 -0-- 0000 -0-- 0000
CAP2M2
CAP3M2
FLTCK2
QEIM0
—
—
—
—
FLT3EN
FLT2EN
FLTCK1
PDEC1
FLTCK0 -000 0000 -000 0000
PDEC0 0000 0000 0000 0000
VELM
QERR
UP/DOWN QEIM2
Legend:
Note 1:
x= unknown, u= unchanged, -= unimplemented. Shaded cells are not used by the Motion Feedback Module.
Register name and function determined by which submodule is selected (IC/QEI, respectively). See Section 16.1.10 “Other
Operating Modes” for more information.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 179
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 180
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
The PWM module has the following features:
17.0 POWER CONTROL PWM
MODULE
• Up to eight PWM I/O pins with four duty cycle
generators. Pins can be paired to get a complete
The Power Control PWM module simplifies the task of
generating multiple, synchronized Pulse-Width
Modulated (PWM) outputs for use in the control of
motor controllers and power conversion applications.
In particular, the following power and motion control
applications are supported by the PWM module:
half-bridge control.
• Up to 14-bit resolution, depending upon the PWM
period.
• “On-the-fly” PWM frequency changes.
• Edge and Center-Aligned Output modes.
• Single-Pulse Generation mode.
• Three-Phase and Single-Phase AC Induction
Motors
• Programmable dead-time control between paired
PWMs.
• Switched Reluctance Motors
• Brushless DC (BLDC) Motors
• Uninterruptible Power Supplies (UPS)
• Multiple DC Brush Motors
• Interrupt support for asymmetrical updates in
Center-Aligned mode.
• Output override for Electrically Commutated
Motor (ECM) operation; for example, BLDC.
• Special Event Trigger comparator for scheduling
other peripheral events.
• PWM outputs disable feature sets PWM outputs
to their inactive state when in Debug mode.
The Power Control PWM module supports three PWM
generators
and
six
output
channels
on
PIC18F2331/2431 devices, and four generators and
eight channels on PIC18F4331/4431 devices. A simpli-
fied block diagram of the module is shown in
Figure 17-1. Figure 17-2 and Figure 17-3 show how
the module hardware is configured for each PWM
output pair for the Complementary and Independent
Output modes.
Each functional unit of the PWM module will be
discussed in subsequent sections.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 181
PIC18F2331/2431/4331/4431
FIGURE 17-1:
POWER CONTROL PWM MODULE BLOCK DIAGRAM
Internal Data Bus
8
PWMCON0
PWM Enable and Mode
8
8
8
8
PWMCON1
DTCON
Dead-Time Control
Fault Pin Control
FLTCONFIG
PWM Manual Control
OVDCON<D/S>
(1)
PWM Generator #3
PDC3 Buffer
8
PDC3
Channel 3
Dead-Time Generator
and Override Logic
(2)
(2)
Comparator
PWM7
PWM6
(2)
8
PWM
Generator 2
Channel 2
Dead-Time Generator
and Override Logic
PWM5
PWM4
PTMR
Comparator
PTPER
Output
Driver
Block
PWM
Generator 1
Channel 1
Dead-Time Generator
and Override Logic
PWM3
PWM2
PWM
Generator 0
Channel 0
Dead-Time Generator
and Override Logic
PWM1
PWM0
8
8
PTPER Buffer
FLTA
PTCON
(2)
FLTB
Special Event
Postscaler
Comparator
Special Event Trigger
SEVTDIR
PTDIR
8
SEVTCMP
Note 1: Only PWM Generator 3 is shown in detail. The other generators are identical; their details are omitted for clarity.
2: PWM Generator 3 and its logic, PWM channels 6 and 7, and FLTB and its associated logic are not implemented on
PIC18F2331/2431 devices.
DS39616C-page 182
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 17-2:
PWM MODULE BLOCK DIAGRAM, ONE OUTPUT PAIR, COMPLEMENTARY MODE
VDD
Dead-Band
Generator
PWM1
Duty Cycle Comparator
HPOL
LPOL
PWM Duty Cycle Register
PWM0
Fault Override Values
Channel Override Values
Fault A Pin
Fault B Pin
Fault Pin Assignment
Logic
Note:
In the Complementary mode, the even channel cannot be forced active by a Fault or override event when the odd channel is
active. The even channel is always the complement of the odd channel and is inactive, with dead time inserted, before the odd
channel is driven to its active state.
FIGURE 17-3:
PWM MODULE BLOCK DIAGRAM, ONE OUTPUT PAIR, INDEPENDENT MODE
VDD
PWM Duty Cycle Register
PWM1
Duty Cycle Comparator
HPOL
VDD
PWM0
Fault Override Values
LPOL
Channel Override Values
Fault A Pin
Fault B Pin
Fault Pin Assignment
Logic
This module contains four duty cycle generators,
numbered 0 through 3. The module has eight PWM
output pins, numbered 0 through 7. The eight PWM
outputs are grouped into output pairs of even and odd
numbered outputs. In Complementary modes, the even
PWM pins must always be the complement of the
corresponding odd PWM pin. For example, PWM0 will
be the complement of PWM1, PWM2 will be the
complement of PWM3 and so on. The dead-time
generator inserts an OFF period called “dead time”
between the going OFF of one pin to the going ON of
the complementary pin of the paired pins. This is to
prevent damage to the power switching devices that
will be connected to the PWM output pins.
The time base for the PWM module is provided by its
own 12-bit timer, which also incorporates selectable
prescaler and postscaler options.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 183
PIC18F2331/2431/4331/4431
17.1 Control Registers
17.2 Module Functionality
The operation of the PWM module is controlled by a
total of 22 registers. Eight of these are used to
configure the features of the module:
The PWM module supports several modes of operation
that are beneficial for specific power and motor control
applications. Each mode of operation is described in
subsequent sections.
• PWM Timer Control Register 0 (PTCON0)
• PWM Timer Control Register 1 (PTCON1)
• PWM Control Register 0 (PWMCON0)
• PWM Control Register 1 (PWMCON1)
• Dead-Time Control Register (DTCON)
• Output Override Control Register (OVDCOND)
• Output State Register (OVDCONS)
The PWM module is composed of several functional
blocks. The operation of each is explained separately
in relation to the several modes of operation:
• PWM Time Base
• PWM Time Base Interrupts
• PWM Period
• PWM Duty Cycle
• Fault Configuration Register (FLTCONFIG)
• Dead-Time Generators
• PWM Output Overrides
• PWM Fault Inputs
There are also 14 registers that are configured as
seven register pairs of 16 bits. These are used for the
configuration values of specific features. They are:
• PWM Special Event Trigger
• PWM Time Base Registers (PTMRH and PTMRL)
• PWM Time Base Period Registers (PTPERH and
PTPERL)
17.3 PWM Time Base
• PWM Special Event Trigger Compare Registers
(SEVTCMPH and SEVTCMPL)
The PWM time base is provided by a 12-bit timer with
prescaler and postscaler functions. A simplified block
diagram of the PWM time base is shown in Figure 17-4.
The PWM time base is configured through the
PTCON0 and PTCON1 registers. The time base is
enabled or disabled by respectively setting or clearing
the PTEN bit in the PTCON1 register.
• PWM Duty Cycle #0 Registers
(PDC0H and PDC0L)
• PWM Duty Cycle #1 Registers
(PDC1H and PDC1L)
• PWM Duty Cycle #2 Registers
(PDC2H and PDC2L)
Note:
The PTMR register pair (PTMRL:PTMRH)
is not cleared when the PTEN bit is
cleared in software.
• PWM Duty Cycle #3 Registers
(PDC3H and PDC3L)
All of these register pairs are double-buffered.
DS39616C-page 184
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 17-4:
PWM TIME BASE BLOCK DIAGRAM
PTMR Register
PTMR Clock
Timer Reset
Up/Down
Zero Match
Comparator
Timer
Direction
Control
PTDIR
Period Match
PTMOD1
Comparator
PTPER
Duty Cycle Load
Period Load
PTPER Buffer
Update Disable (UDIS)
Zero Match
Period Match
PTMOD1
Clock
Control
PTMR Clock
PTEN
PTMOD0
Prescaler
1:1, 1:4, 1:16, 1:64
FOSC/4
Zero Match
Postscaler
1:1-1:16
Interrupt
Control
PTIF
Period Match
PTMOD1
PTMOD0
The PWM time base can be configured for four different
modes of operation:
These four modes are selected by the
PTMOD1:PTMOD0 bits in the PTCON0 register. The
Free-Running mode produces edge-aligned PWM
generation. The Continuous Up/Down Count modes
produce center-aligned PWM generation. The
Single-Shot mode allows the PWM module to support
pulse control of certain Electronically Commutated
Motors (ECMs) and produces edge-aligned operation.
• Free-Running mode
• Single-Shot mode
• Continuous Up/Down Count mode
• Continuous Up/Down Count mode with interrupts
for double updates
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 185
PIC18F2331/2431/4331/4431
REGISTER 17-1: PTCON0: PWM TIMER CONTROL REGISTER 0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
PTOPS3
PTOPS2
PTOPS1
PTOPS0
PTCKPS1
PTCKPS0
PTMOD1
PTMOD0
bit 7
bit 0
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
bit 7-4
PTOPS3:PTOPS0: PWM Time Base Output Postscale Select bits
0000= 1:1 Postscale
0001= 1:2 Postscale
.
.
.
1111= 1:16 Postscale
bit 3-2
bit 1-0
PTCKPS1:PTCKPS0: PWM Time Base Input Clock Prescale Select bits
00= PWM time base input clock is FOSC/4 (1:1 prescale)
01= PWM time base input clock is FOSC/16 (1:4 prescale)
10= PWM time base input clock is FOSC/64 (1:16 prescale)
11= PWM time base input clock is FOSC/256 (1:64 prescale)
PTMOD1:PTMOD0: PWM Time Base Mode Select bits
11= PWM time base operates in a Continuous Up/Down Count mode with interrupts for double PWM
updates
10= PWM time base operates in a Continuous Up/Down Count mode
01= PWM time base configured for Single-Shot mode
00= PWM time base operates in a Free-Running mode
REGISTER 17-2: PTCON1: PWM TIMER CONTROL REGISTER 1
R/W-0
PTEN
R-0
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
PTDIR
bit 7
bit 0
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
bit 7
PTEN: PWM Time Base Timer Enable bit
1= PWM time base is on
0= PWM time base is off
bit 6
PTDIR: PWM Time Base Count Direction Status bit
1= PWM time base counts down
0= PWM time base counts up
bit 5-0
Unimplemented: Read as ‘0’
DS39616C-page 186
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 17-3: PWMCON0: PWM CONTROL REGISTER 0
U-0
—
R/W-1(1)
R/W-1(1)
R/W-1(1)
R/W-0
PMOD3(3)
R/W-0
R/W-0
R/W-0
PWMEN2
PWMEN1
PWMEN0
PMOD2
PMOD1
PMOD0
bit 7
bit 0
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
bit 7
Unimplemented: Read as ‘0’
bit 6-4
PWMEN2:PWMEN0: PWM Module Enable bits(1)
111= All odd PWM I/O pins enabled for PWM output(2)
110= PWM1, PWM3 pins enabled for PWM output
101= All PWM I/O pins enabled for PWM output(2)
100= PWM0, PWM1, PWM2, PWM3, PWM4 and PWM5 pins enabled for PWM output
011= PWM0, PWM1, PWM2 and PWM3 I/O pins enabled for PWM output
010= PWM0 and PWM1 pins enabled for PWM output
001= PWM1 pin is enabled for PWM output
000= PWM module disabled; all PWM I/O pins are general purpose I/O
bit 3-0
PMOD3:PMOD0: PWM Output Pair Mode bits
For PMOD0:
1= PWM I/O pin pair (PWM0, PWM1) is in the Independent mode
0= PWM I/O pin pair (PWM0, PWM1) is in the Complementary mode
For PMOD1:
1= PWM I/O pin pair (PWM2, PWM3) is in the Independent mode
0= PWM I/O pin pair (PWM2, PWM3) is in the Complementary mode
For PMOD2:
1= PWM I/O pin pair (PWM4, PWM5) is in the Independent mode
0= PWM I/O pin pair (PWM4, PWM5) is in the Complementary mode
For PMOD3:(3)
1= PWM I/O pin pair (PWM6, PWM7) is in the Independent mode
0= PWM I/O pin pair (PWM6, PWM7) is in the Complementary mode
Note 1: Reset condition of PWMEN bits depends on PWMPIN Configuration bit.
2: When PWMEN2:PWMEN0 = 101, PWM<5:0> outputs are enabled for PIC18F2331/2431 devices;
PWM<7:0> outputs are enabled for PIC18F4331/4431 devices.
When PWMEN2:PWMEN0 = 111, PWM outputs 1, 3 and 5 are enabled in PIC18F2331/2431 devices;
PWM outputs 1, 3, 5 and 7 are enabled in PIC18F4331/4431 devices.
3: Unimplemented in PIC18F2331/2431 devices; maintain these bits clear.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 187
PIC18F2331/2431/4331/4431
REGISTER 17-4: PWMCON1: PWM CONTROL REGISTER 1
R/W-0
SEVOPS3
bit 7
R/W-0
R/W-0
R/W-0
R/W-0
U-0
—
R/W-0
UDIS
R/W-0
SEVOPS2
SEVOPS1
SEVOPS0
SEVTDIR
OSYNC
bit 0
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
bit 7-4
SEVOPS3:SEVOPS0: PWM Special Event Trigger Output Postscale Select bits
0000= 1:1 Postscale
0001= 1:2 Postscale
.
.
.
1111= 1:16 Postscale
bit 3
SEVTDIR: Special Event Trigger Time Base Direction bit
1= A Special Event Trigger will occur when the PWM time base is counting downwards
0= A Special Event Trigger will occur when the PWM time base is counting upwards
bit 2
bit 1
Unimplemented: Read as ‘0’
UDIS: PWM Update Disable bit
1= Updates from Duty Cycle and Period Buffer registers are disabled
0= Updates from Duty Cycle and Period Buffer registers are enabled
bit 0
OSYNC: PWM Output Override Synchronization bit
1= Output overrides via the OVDCON register are synchronized to the PWM time base
0= Output overrides via the OVDCON register are asynchronous
17.3.1
FREE-RUNNING MODE
Note:
Since the PWM compare outputs are
driven to the active state when the PWM
time base is counting downwards and
matches the duty cycle value, the PWM
outputs are held inactive during the first
half of the first period of the Continuous
Up/Down Count mode until PTMR begins
to count down from the PTPER value.
In the Free-Running mode, the PWM Time Base regis-
ters (PTMRL and PTMRH) will begin counting upwards
until the value in the PWM Time Base Period register,
PTPER (PTPERL and PTPERH), is matched. The
PTMR registers will be reset on the following input
clock edge and the time base will continue counting
upwards as long as the PTEN bit remains set.
17.3.2
SINGLE-SHOT MODE
17.3.4
PWM TIME BASE PRESCALER
In the Single-Shot mode, the PWM time base will begin
counting upwards when the PTEN bit is set. When the
value in the PTMR register matches the PTPER regis-
ter, the PTMR register will be reset on the following
input clock edge and the PTEN bit will be cleared by the
hardware to halt the time base.
The input clock to PTMR (FOSC/4) has prescaler
options of 1:1, 1:4, 1:16 or 1:64. These are selected by
control bits, PTCKPS<1:0>, in the PTCON0 register.
The prescaler counter is cleared when any of the
following occurs:
• Write to the PTMR register
• Write to the PTCON (PTCON0 or PTCON1)
register
17.3.3
CONTINUOUS UP/DOWN COUNT
MODES
• Any device Reset
In Continuous Up/Down Count modes, the PWM time
base counts upwards until the value in the PTPER
register matches with the PTMR register. On the
following input clock edge, the timer counts
downwards. The PTDIR bit in the PTCON1 register is
read-only and indicates the counting direction. The
PTDIR bit is set when the timer counts downwards.
Note:
The PTMR register is not cleared when
PTCONx is written.
DS39616C-page 188
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Table 17-1 shows the minimum PWM frequencies that
can be generated with the PWM time base and the
prescaler. An operating frequency of 40 MHz
(FCYC = 10 MHz) and PTPER = 0xFFF is assumed in
the table. The PWM module must be capable of gener-
ating PWM signals at the line frequency (50 Hz or
60 Hz) for certain power control applications.
17.3.5
PWM TIME BASE POSTSCALER
The match output of PTMR can optionally be
postscaled through a 4-bit postscaler (which gives a
1:1 to 1:16 scaling inclusive) to generate an interrupt.
The postscaler counter is cleared when any of the
following occurs:
• Write to the PTMR register
• Write to the PTCON register
• Any device Reset
TABLE 17-1: MINIMUM PWM FREQUENCY
Minimum PWM Frequencies vs. Prescaler Value
for FCYC = 10 MIPS (PTPER = 0FFFh)
The PTMR register is not cleared when PTCON is
written.
PWM Frequency
Edge-Aligned
PWM Frequency
Center-Aligned
Prescale
17.4 PWM Time Base Interrupts
1:1
1:4
2441 Hz
610 Hz
153 Hz
38 Hz
1221 Hz
305 Hz
76 Hz
The PWM timer can generate interrupts based on the
modes of operation selected by the PTMOD<1:0> bits
and the postscaler bits (PTOPS<3:0>).
1:16
1:64
19 Hz
17.4.1
INTERRUPTS IN FREE-RUNNING
MODE
When the PWM time base is in the Free-Running mode
(PTMOD<1:0> = 00), an interrupt event is generated
each time a match with the PTPER register occurs. The
PTMR register is reset to zero in the following clock edge.
Using a postscaler selection other than 1:1 will reduce
the frequency of interrupt events.
FIGURE 17-5:
PWM TIME BASE INTERRUPT TIMING, FREE-RUNNING MODE
A: PRESCALER = 1:1
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
FOSC/4
PTMR
1
FFEh
FFFh
000h
001h
002h
PTMR_INT_REQ
PTIF bit
B: PRESCALER = 1:4
Q4
Q4
Qc
Qc Qc Qc
Qc
Qc
Qc Qc
Qc
Qc Qc
Qc
Qc
Qc Qc
001h
Qc
Qc
Qc Qc
002h
Qc
1
PTMR
FFEh
FFFh
000h
PTMR_INT_REQ
PTIF bit
Note 1: PWM Time Base Period register, PTPER, is loaded with the value FFFh for this example.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 189
PIC18F2331/2431/4331/4431
17.4.2
INTERRUPTS IN SINGLE-SHOT
MODE
17.4.3
INTERRUPTS IN CONTINUOUS
UP/DOWN COUNT MODE
When the PWM time base is in the Single-Shot mode
(PTMOD<1:0> = 01), an interrupt event is generated
when a match with the PTPER register occurs. The
PWM Time Base register (PTMR) is reset to zero on
the following input clock edge and the PTEN bit is
cleared. The postscaler selection bits have no effect in
this Timer mode.
In the Continuous Up/Down Count mode
(PTMOD<1:0> = 10), an interrupt event is generated
each time the value of the PTMR register becomes
zero and the PWM time base begins to count upwards.
The postscaler selection bits may be used in this mode
of the timer to reduce the frequency of the interrupt
events. Figure 17-7 shows the interrupts in Continuous
Up/Down Count mode.
FIGURE 17-6:
PWM TIME BASE INTERRUPT TIMING, SINGLE-SHOT MODE
A: PRESCALER = 1:1
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
FOSC/4
PTMR
2
FFEh
FFFh
000h
000h
000h
1
1
1
PTMR_INT_REQ
PTIF bit
B: PRESCALER = 1:4
Q4
Q4
Qc
Qc
Qc Qc
Qc
Qc
Qc Qc
FFFh
Qc Qc
Qc
Qc
Qc
Qc Qc
000h
Qc
Qc Qc Qc
Qc
2
PTMR
PTMR_INT_REQ
PTIF bit
FFEh
000h
000h
1
1
1
Note 1: Interrupt flag bit, PTIF, is sampled here (every Q1).
2: PWM Time Base Period register, PTPER, is loaded with the value FFFh for this example.
DS39616C-page 190
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 17-7:
PWM TIME BASE INTERRUPT, CONTINUOUS UP/DOWN COUNT MODE
A: PRESCALER = 1:1
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
FOSC/4
PTMR
PTDIR bit
002h
001h
000h
001h
002h
PTMR_INT_REQ
1
1
1
1
PTIF bit
B: PRESCALER = 1:4
Q4
Q4
Qc
Qc Qc
Qc
Qc
Qc Qc
001h
Qc Qc
Qc Qc
Qc
Qc
Qc Qc
001h
Qc
Qc Qc Qc
Qc
002h
000h
002h
PTMR
PTDIR bit
1
1
1
1
PTMR_INT_REQ
PTIF bit
Note 1: Interrupt flag bit, PTIF, is sampled here (every Q1).
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 191
PIC18F2331/2431/4331/4431
17.4.4
INTERRUPTS IN DOUBLE UPDATE
MODE
Note:
Do not change PTMOD while PTEN is
active. It will yield unexpected results. To
change the PWM Timer mode of opera-
tion, first clear PTEN bit, load PTMOD with
required data and then set PTEN.
This mode is available in Continuous Up/Down Count
mode. In the Double Update mode (PTMOD<1:0> = 11),
an interrupt event is generated each time the PTMR
register is equal to zero and each time the PTMR
matches with PTPER register. Figure 17-8 shows the
interrupts in Continuous Up/Down Count mode with
double updates.
The Double Update mode provides two additional
functions to the user in Center-Aligned mode.
1. The control loop bandwidth is doubled because
the PWM duty cycles can be updated twice per
period.
2. Asymmetrical center-aligned PWM waveforms
can be generated, which are useful for
minimizing output waveform distortion in certain
motor control applications.
FIGURE 17-8:
PWM TIME BASE INTERRUPT, CONTINUOUS UP/DOWN COUNT MODE WITH
DOUBLE UPDATES
A: PRESCALER = 1:1
Case 1: PTMR Counting Upwards
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
OSC1
2
PTMR
3FDh
3FEh
3FFh
3FEh
3FDh
PTDIR bit
PTMR_INT_REQ
PTIF bit
1
1
1
1
Case 2: PTMR Counting Downwards
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
Q1 Q2 Q3
Q4
OSC1
PTMR
PTDIR bit
002h
001h
000h
001h
002h
PTMR_INT_REQ
1
1
1
1
PTIF bit
Note 1: Interrupt flag bit, PTIF, is sampled here (every Q1).
2: PWM Time Base Period register, PTPER, is loaded with the value 3FFh for this example.
DS39616C-page 192
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
The maximum resolution (in bits) for a given device
oscillator and PWM frequency can be determined from
the following formula:
17.5 PWM Period
The PWM period is defined by the PTPER register pair
(PTPERL and PTPERH). The PWM period has 12-bit
resolution by combining 4 LSBs of PTPERH and 8 bits
of PTPERL. PTPER is a double-buffered register used
to set the counting period for the PWM time base.
EQUATION 17-4: PWM RESOLUTION
FOSC
FPWM
log
The PTPER register contents are loaded into the
PTPER register at the following times:
Resolution =
log(2)
• Free-Running and Single-Shot modes: When the
PTMR register is reset to zero after a match with
the PTPER register.
The PWM resolutions and frequencies are shown for a
selection of execution speeds and PTPER values in
Table 17-2. The PWM frequencies in Table 17-2 are
calculated for Edge-Aligned PWM mode. For
Center-Aligned mode, the PWM frequencies will be
approximately one-half the values indicated in this
table.
• Continuous Up/Down Count modes: When the
PTMR register is zero. The value held in the
PTPER register is automatically loaded into the
PTPER register when the PWM time base is
disabled (PTEN = 0). Figure 17-9 and
Figure 17-10 indicate the times when the contents
of the PTPER register are loaded into the actual
PTPER register.
TABLE 17-2: EXAMPLE PWMFREQUENCIES
AND RESOLUTIONS
PWM Frequency = 1/TPWM
The PWM period can be calculated from the following
formulas:
PTPER
PWM
PWM
FOSC
MIPS
Value Resolution Frequency
EQUATION 17-1: PWM PERIOD FOR
FREE-RUNNING MODE
40 MHz
40 MHz
40 MHz
40 MHz
40 MHz
40 MHz
40 MHz
40 MHz
40 MHz
10
10
10
10
10
10
10
10
10
0FFFh
07FFh
03FFh
01FFh
FFh
14 bits
13 bits
12 bits
11 bits
10 bits
9 bits
2.4 kHz
4.9 kHz
9.8 kHz
19.5 kHz
39.0 kHz
78.1 kHz
156.2 kHz
312.5 kHz
625 kHz
1.5 kHz
6.1 kHz
24.4 kHz
610 Hz
(PTPER + 1) x PTMRPS
TPWM =
FOSC/4
EQUATION 17-2: PWM PERIOD FOR
CONTINUOUS UP/DOWN
COUNT MODE
7Fh
3Fh
8 bits
1Fh
7 bits
0Fh
6 bits
(2 x PTPER) x PTMRPS
TPWM =
FOSC
4
25 MHz 6.25 0FFFh
25 MHz 6.25 03FFh
14 bits
12 bits
10 bits
14 bits
12 bits
10 bits
14 bits
12 bits
10 bits
14 bits
12 bits
10 bits
25 MHz 6.25
FFh
10 MHz
10 MHz
10 MHz
5 MHz
5 MHz
5 MHz
4 MHz
4 MHz
4 MHz
2.5 0FFFh
The PWM frequency is the inverse of period; or:
2.5
2.5
03FFh
FFh
2.4 kHz
9.8 kHz
305 Hz
EQUATION 17-3: PWM FREQUENCY
1.25 0FFFh
1.25 03FFh
1
PWM Frequency =
PWM Period
1.2 kHz
4.9 kHz
244 Hz
1.25
FFh
0FFFh
03FFh
FFh
1
1
1
976 Hz
3.9 kHz
Note: For center-aligned operation, PWM frequencies
will be approximately 1/2 the value indicated in
the table.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 193
PIC18F2331/2431/4331/4431
FIGURE 17-9:
PWM PERIOD BUFFER UPDATES IN FREE-RUNNING MODE
Period Value Loaded from PTPER Register
7
New PTPER Value = 007
6
5
4
4
4
Old PTPER Value = 004
3
3
3
2
2
2
1
1
1
0
0
0
New Value Written to PTPER Register
FIGURE 17-10:
PWM PERIOD BUFFER UPDATES IN CONTINUOUS UP/DOWN COUNT MODE
Period Value Loaded from PTPER Register
7
New PTPER Value = 007
6
6
5
5
4
Old PTPER Value = 004
4
4
3
3
3
3
2
2
2
2
1
1
1
1
0
0
0
New Value Written to PTPER Register
DS39616C-page 194
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
The value in each Duty Cycle register determines the
amount of time that the PWM output is in the active
17.6 PWM Duty Cycle
PWM duty cycle is defined by the PDCx (PDCxL and
PDCxH) registers. There are a total of four PWM Duty
Cycle registers for four pairs of PWM channels. The
Duty Cycle registers have 14-bit resolution by combin-
ing six LSbs of PDCxH with the 8 bits of PDCxL. PDCx
is a double-buffered register used to set the counting
period for the PWM time base.
state. The upper 12 bits of PDCx holds the actual duty
cycle value from PTMRH/L<11:0>, while the lower 2
bits control which internal Q clock the duty cycle match
will occur. This 2-bit value is decoded from the Q clocks
as shown in Figure 17-11 (when the prescaler is 1:1 or
PTCKPS<1:0> = 00).
In Edge-Aligned mode, the PWM period starts at Q1
and ends when the Duty Cycle register matches the
PTMR register as follows. The duty cycle match is con-
sidered when the upper 12 bits of the PDCx is equal to
the PTMR and the lower 2 bits are equal to Q1, Q2, Q3
or Q4, depending on the lower two bits of the PDCx
(when the prescaler is 1:1 or PTCKPS<1:0> = 00).
17.6.1
PWM DUTY CYCLE REGISTERS
There are four 14-bit Special Function Registers used
to specify duty cycle values for the PWM module:
• PDC0 (PDC0L and PDC0H)
• PDC1 (PDC1L and PDC1H)
• PDC2 (PDC2L and PDC2H)
• PDC3 (PDC3L and PDC3H)
Note:
When the prescaler is not 1:1
(PTCKPS<1:0> ≠ ~00), the duty cycle
match occurs at the Q1 clock of the
instruction cycle when the PTMR and
PDCx match occurs.
Each compare unit has logic that allows override of the
PWM signals. This logic also ensures that the PWM
signals will complement each other (with dead-time
insertion) in Complementary mode (see Section 17.7
“Dead-Time Generators”).
FIGURE 17-11:
DUTY CYCLE COMPARISON
PTMRH<7:0>
PTMRL<7:0>
PTMR<11:0>
Q Clocks(1)
<1:0>
PTMRH<3:0>
Unused
PTMRL<7:0>
Comparator
Unused
PDCxH<5:0>
PDCxL<7:0>
PDCx<13:0>
PDCxH<7:0>
PDCxL<7:0>
Note 1: This value is decoded from the Q clocks:
00= duty cycle match occurs on Q1
01= duty cycle match occurs on Q2
10= duty cycle match occurs on Q3
11= duty cycle match occurs on Q4
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 195
PIC18F2331/2431/4331/4431
17.6.2
DUTY CYCLE REGISTER BUFFERS
17.6.3
EDGE-ALIGNED PWM
The four PWM Duty Cycle registers are
double-buffered to allow glitchless updates of the PWM
outputs. For each duty cycle block, there is a Duty
Cycle Buffer register that is accessible by the user and
a second Duty Cycle register that holds the actual
compare value used in the present PWM period.
Edge-aligned PWM signals are produced by the
module when the PWM time base is in the
Free-Running mode or the Single-Shot mode. For
edge-aligned PWM outputs, the output for a given
PWM channel has a period specified by the value
loaded in PTPER and a duty cycle specified by the
appropriate Duty Cycle register (see Figure 17-12).
The PWM output is driven active at the beginning of the
period (PTMR = 0) and is driven inactive when the
value in the Duty Cycle register matches PTMR. A new
cycle is started when PTMR matches the PTPER as
explained in the PWM period section.
In Edge-Aligned PWM Output mode, a new duty cycle
value will be updated whenever a PTMR match with the
PTPER register occurs and PTMR is reset as shown in
Figure 17-12. Also, the contents of the duty cycle buffers
are automatically loaded into the Duty Cycle registers
when the PWM time base is disabled (PTEN = 0).
If the value in a particular Duty Cycle register is zero,
then the output on the corresponding PWM pin will be
inactive for the entire PWM period. In addition, the out-
put on the PWM pin will be active for the entire PWM
period if the value in the Duty Cycle register is greater
than the value held in the PTPER register.
When the PWM time base is in the Continuous
Up/Down Count mode, new duty cycle values will be
updated when the value of the PTMR register is zero
and the PWM time base begins to count upwards. The
contents of the duty cycle buffers are automatically
loaded into the Duty Cycle registers when the PWM
time base is disabled (PTEN = 0). Figure 17-13 shows
the timings when the duty cycle update occurs for the
Continuous Up/Down Count mode. In this mode, up to
one entire PWM period is available for calculating and
loading the new PWM duty cycle before changes take
effect.
FIGURE 17-12:
EDGE-ALIGNED PWM
New Duty Cycle Latched
PTPER
When the PWM time base is in the Continuous
Up/Down Count mode with double updates, new duty
cycle values will be updated when the value of the
PTMR register is zero and when the value of the PTMR
register matches the value in the PTPER register. The
contents of the duty cycle buffers are automatically
loaded into the Duty Cycle registers during both of the
previously described conditions. Figure 17-14 shows
the duty cycle updates for Continuous Up/Down Count
mode with double updates. In this mode, only up to half
of a PWM period is available for calculating and loading
the new PWM duty cycle before changes take effect.
PTMR
Value
PDCx
(old)
PDCx
(new)
0
Duty Cycle
Active at
beginning
of period
Period
FIGURE 17-13:
DUTY CYCLE UPDATE TIMES IN CONTINUOUS UP/DOWN COUNT MODE
Duty Cycle Value Loaded from Buffer Register
PWM Output
PTMR Value
New Value Written to Duty Cycle Buffer
DS39616C-page 196
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 17-14:
DUTY CYCLE UPDATE TIMES IN CONTINUOUS UP/DOWN COUNT MODE WITH
DOUBLE UPDATES
Duty Cycle Value Loaded from Buffer Register
PWM Output
PTMR Value
New Values Written to Duty Cycle Buffer
inactive for the entire PWM period. In addition, the
output on the PWM pin will be active for the entire PWM
period if the value in the Duty Cycle register is equal to
or greater than the value in the PTPER register.
17.6.4
CENTER-ALIGNED PWM
Center-aligned PWM signals are produced by the
module when the PWM time base is configured in a
Continuous Up/Down Count mode (see Figure 17-15).
The PWM compare output is driven to the active state
when the value of the Duty Cycle register matches the
value of PTMR and the PWM time base is counting
downwards (PTDIR = 1). The PWM compare output
will be driven to the inactive state when the PWM time
base is counting upwards (PTDIR = 0) and the value in
the PTMR register matches the duty cycle value. If the
value in a particular Duty Cycle register is zero, then
the output on the corresponding PWM pin will be
Note:
When the PWM
is started in
Center-Aligned mode, the PWM Time
Base Period register (PTPER) is loaded
into the PWM Time Base register (PTMR)
and the PTMR is configured automatically
to start down counting. This is done to
ensure that all the PWM signals don’t start
at the same time.
FIGURE 17-15:
START OF CENTER-ALIGNED PWM
Period/2
PTPER
PTMR
Value
Duty
Cycle
0
Duty Cycle
Start of
first
PWM
period
Period
Period
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 197
PIC18F2331/2431/4331/4431
17.6.5
COMPLEMENTARY PWM
OPERATION
FIGURE 17-16:
TYPICAL LOAD FOR
COMPLEMENTARY PWM
OUTPUTS
The Complementary mode of PWM operation is useful
to drive one or more power switches in half-bridge
configuration as shown in Figure 17-16. This inverter
topology is typical for a 3-phase induction motor,
brushless DC motor or a 3-phase Uninterruptible
Power Supply (UPS) control applications.
+V
3-Phase
Load
Each upper/lower power switch pair is fed by a
complementary PWM signal. Dead time may be
optionally inserted during device switching, where both
outputs are inactive for
a
short period (see
Section 17.7 “Dead-Time Generators”).
In Complementary mode, the duty cycle comparison
units are assigned to the PWM outputs as follows:
• PDC0 register controls PWM1/PWM0 outputs
• PDC1 register controls PWM3/PWM2 outputs
• PDC2 register controls PWM5/PWM4 outputs
• PDC3 register controls PWM7/PWM6 outputs
The Complementary mode is selected for each PWM
I/O pin pair by clearing the appropriate PMODx bit in
the PWMCON0 register. The PWM I/O pins are set to
Complementary mode by default upon all kinds of
device Resets.
PWM1/3/5/7 are the main PWMs that are controlled by
the PDCx registers and PWM0/2/4/6 are the
complemented outputs. When using the PWMs to
control the half bridge, the odd numbered PWMs can
be used to control the upper power switch and the even
numbered PWMs used for the lower switches.
DS39616C-page 198
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
17.7.1
DEAD-TIME INSERTION
17.7 Dead-Time Generators
Each complementary output pair for the PWM module
has a 6-bit down counter used to produce the
dead-time insertion. As shown in Figure 17-17, each
dead-time unit has a rising and falling edge detector
connected to the duty cycle comparison output. The
dead time is loaded into the timer on the detected PWM
edge event. Depending on whether the edge is rising or
falling, one of the transitions on the complementary
outputs is delayed until the timer counts down to zero.
A timing diagram, indicating the dead-time insertion for
one pair of PWM outputs, is shown in Figure 17-18.
In power inverter applications, where the PWMs are
used in Complementary mode to control the upper and
lower switches of a half-bridge, a dead-time insertion is
highly recommended. The dead-time insertion keeps
both outputs in inactive state for a brief time. This
avoids any overlap in the switching during the state
change of the power devices due to TON and TOFF
characteristics.
Because the power output devices cannot switch
instantaneously, some amount of time must be pro-
vided between the turn-off event of one PWM output in
a complementary pair and the turn-on event of the
other transistor. The PWM module allows dead time to
be programmed. The following sections explain the
dead-time block in detail.
FIGURE 17-17:
DEAD-TIME CONTROL UNIT BLOCK DIAGRAM FOR ONE PWM OUTPUT PAIR
Dead Time
Select Bits
Zero Compare
Clock Control
FOSC
6-Bit Down Counter
and Prescaler
Odd PWM Signal to
Output Control Block
Dead Time
Prescale
Even PWM Signal to
Output Control Block
Dead-Time Register
Duty Cycle
Compare Input
FIGURE 17-18:
DEAD-TIME INSERTION FOR COMPLEMENTARY PWM
t
t
d
d
PDC1
Compare
Output
PWM1
PWM0
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 199
PIC18F2331/2431/4331/4431
REGISTER 17-5: DTCON: DEAD-TIME CONTROL REGISTER
R/W-0
R/W-0
R/W-0
DT5
R/W-0
DT4
R/W-0
DT3
R/W-0
DT2
R/W-0
DT1
R/W-0
DT0
DTPS1
DTPS0
bit 7
bit 0
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
bit 7-6
DTPS1:DTPS0: Dead-Time Unit A Prescale Select bits
11= Clock source for dead-time unit is FOSC/16
10= Clock source for dead-time unit is FOSC/8
01= Clock source for dead-time unit is FOSC/4
00= Clock source for dead-time unit is FOSC/2
bit 5-0
DT5:DT0: Unsigned 6-Bit Dead-Time Value for Dead-Time Unit bits
17.7.2
DEAD-TIME RANGES
17.7.3
DECREMENTING THE DEAD-TIME
COUNTER
The amount of dead time provided by the dead-time
unit is selected by specifying the input clock prescaler
value and a 6-bit unsigned value defined in the DTCON
register. Four input clock prescaler selections have
been provided to allow a suitable range of dead times
based on the device operating frequency. FOSC/2,
FOSC/4, FOSC/8 and FOSC/16 are the clock prescaler
options available using the DTPS1:DTPS0 control bits
in the DTCON register.
The dead-time counter is clocked from any of the Q
clocks based on the following conditions.
1. The dead-time counter is clocked on Q1 when:
• The DTPS bits are set to any of the following
dead-time prescaler settings: FOSC/4,
FOSC/8, FOSC/16
• The PWM Time Base Prescale bits
(PTCKPS) are set to any of the following
prescale ratios: FOSC/16, FOSC/64, FOSC/256
After selecting an appropriate prescaler value, the
dead time is adjusted by loading a 6-bit unsigned value
into DTCON<5:0>. The dead-time unit prescaler is
cleared on any of the following events:
2. The dead-time counter is clocked by a pair of Q
clocks when the PWM Time Base Prescale bits
are set to 1:1 (PTCKPS1:PTCKPS0 = 00,
FOSC/4) and the dead-time counter is clocked by
the FOSC/2 (DTPS1:DTPS0 = 00).
• On a load of the down timer due to a duty cycle
comparison edge event;
• On a write to the DTCON register; or
• On any device Reset.
3. The dead-time counter is clocked using every
other Q clock, depending on the two LSbs in the
Duty Cycle registers:
• If the PWM duty cycle match occurs on Q1 or
Q3, then the dead-time counter is clocked
using every Q1 and Q3.
• If the PWM duty cycle match occurs on Q2 or
Q4, then the dead-time counter is clocked
using every Q2 and Q4.
4. When the DTPS1:DTPS0 bits are set to any of
the other dead-time prescaler settings (i.e.,
FOSC/4, FOSC/8 or FOSC/16) and the PWM time
base prescaler is set to 1:1, the dead-time
counter is clocked by the Q clock corresponding
to the Q clocks on which the PWM duty cycle
match occurs.
DS39616C-page 200
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
The actual dead time is calculated from the DTCON
register as follows:
17.7.4
DEAD-TIME DISTORTION
Note 1: For small PWM duty cycles, the ratio of
dead time to the active PWM time may
become large. In this case, the inserted
dead time will introduce distortion into
waveforms produced by the PWM mod-
ule. The user can ensure that dead-time
distortion is minimized by keeping the
PWM duty cycle at least three times
larger than the dead time. A similar effect
occurs for duty cycles at or near 100%.
The maximum duty cycle used in the
application should be chosen such that
the minimum inactive time of the signal is
at least three times larger than the dead
time. If the dead time is greater or equal
to the duty cycle of one of the PWM
output pairs, then that PWM pair will be
inactive for the whole period.
Dead Time = Dead Time Value/(FOSC/Prescaler)
Table 17-3 shows example dead-time ranges as a
function of the input clock prescaler selected and the
device operating frequency.
TABLE 17-3: EXAMPLE DEAD-TIME
RANGES
FOSC
(MHz)
Prescaler Dead-Time Dead-Time
MIPS
Selection
Min
Max
40
40
40
40
32
32
32
32
25
25
25
25
20
20
20
20
10
10
10
10
5
10
10
10
10
8
FOSC/2
FOSC/4
FOSC/8
FOSC/16
FOSC/2
FOSC/4
FOSC/8
FOSC/16
FOSC/2
FOSC/4
FOSC/8
FOSC/16
FOSC/2
FOSC/4
FOSC/8
FOSC/16
FOSC/2
FOSC/4
FOSC/8
FOSC/16
FOSC/2
FOSC/4
FOSC/8
FOSC/16
FOSC/2
FOSC/4
FOSC/8
FOSC/16
50 ns
100 ns
200 ns
400 ns
62.5 ns
125 ns
250 ns
500 ns
80 ns
3.2 μs
6.4 μs
12.8 μs
25.6 μs
4 μs
8
8 μs
2: Changing the dead-time values in
DTCON when the PWM is enabled may
result in an undesired situation. Disable
the PWM (PTEN = 0) before changing the
dead-time value
8
16 μs
8
32 μs
6.25
6.25
6.25
6.25
5
5.12 μs
10.2 μs
20.5 μs
41 μs
160 ns
320 ns
640 ns
100 ns
200 ns
400 ns
800 ns
200 ns
400 ns
800 ns
1.6 μs
400 ns
800 ns
1.6 μs
3.2 μs
0.5 μs
1 μs
17.8 Independent PWM Output
Independent PWM mode is used for driving the loads
(as shown in Figure 17-19) for driving one winding of a
switched reluctance motor. A particular PWM output
pair is configured in the Independent Output mode
when the corresponding PMOD bit in the PWMCON0
register is set. No dead-time control is implemented
between the PWM I/O pins when the module is operat-
ing in the Independent PWM mode and both I/O pins
are allowed to be active simultaneously. This mode can
also be used to drive stepper motors.
6.4 μs
5
12.8 μs
25.6 μs
51.2 μs
12.8 μs
25.6 μs
51.2 μs
102.4 μs
25.6 μs
51.2 μs
102.4 μs
204.8 μs
32 μs
5
5
2.5
2.5
2.5
2.5
1.25
1.25
1.25
1.25
1
17.8.1
DUTY CYCLE ASSIGNMENT IN THE
INDEPENDENT PWM MODE
5
5
In the Independent PWM mode, each duty cycle gener-
ator is connected to both PWM output pins in a given
PWM output pair. The odd and the even PWM output
pins are driven with a single PWM duty cycle generator.
PWM1 and PWM0 are driven by the PWM channel
which uses the PDC0 register to set the duty cycle,
PWM3 and PWM2 with PDC1, PWM5 and PWM4 with
PDC2 and PWM7 and PWM6 with PDC3 (see
Figure 17-3 and Register 17-4).
5
4
4
1
64 μs
4
1
2 μs
128 μs
256 μs
4
1
4 μs
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 201
PIC18F2331/2431/4331/4431
OVDCOND and OVDCONS registers are used to
define the PWM override options. The OVDCOND
register contains eight bits, POVD7:POVD0, that
determine which PWM I/O pins will be overridden. The
17.8.2
PWM CHANNEL OVERRIDE
PWM output may be manually overridden for each
PWM channel by using the appropriate bits in the
OVDCOND and OVDCONS registers. The user may
select the following signal output options for each PWM
output pin operating in the Independent PWM mode:
OVDCONS
register
contains
eight
bits,
POUT7:POUT0, that determine the state of the PWM
I/O pins when a particular output is overridden via the
POVD bits.
• I/O pin outputs PWM signal
• I/O pin inactive
The POVD bits are active-low control bits. When the
POVD bits are set, the corresponding POUT bit will
have no effect on the PWM output. In other words, the
pins corresponding to POVD bits that are set will have
the duty PWM cycle set by the PDCx registers. When
one of the POVD bits is cleared, the output on the cor-
responding PWM I/O pin will be determined by the
state of the POUT bit. When a POUT bit is set, the
PWM pin will be driven to its active state. When the
POUT bit is cleared, the PWM pin will be driven to its
inactive state.
• I/O pin active
Refer to Section 17.10 “PWM Output Override” for
details for all the override functions.
FIGURE 17-19:
CENTER CONNECTED
LOAD
+V
Load
PWM1
17.10.1 COMPLEMENTARY OUTPUT MODE
The even numbered PWM I/O pins have override
restrictions when a pair of PWM I/O pins are operating
in the Complementary mode (PMODx = 0). In Comple-
mentary mode, if the even numbered pin is driven
active by clearing the corresponding POVD bit and by
setting POUT bits in the OVDCOND and OVDCONS
registers, the output signal is forced to be the comple-
ment of the odd numbered I/O pin in the pair (see
Figure 17-2 for details).
PWM0
17.9 Single-Pulse PWM Operation
The single-pulse PWM operation is available only in
Edge-Aligned mode. In this mode, the PWM module
will produce single-pulse output. Single-pulse
operation is configured when the PTMOD1:PTMOD0
bits are set to ‘01’ in the PTCON0 register. This mode
of operation is useful for driving certain types of ECMs.
17.10.2 OVERRIDE SYNCHRONIZATION
If the OSYNC bit in the PWMCON1 register is set, all
output overrides performed via the OVDCOND and
OVDCONS registers will be synchronized to the PWM
time base. Synchronous output overrides will occur on
the following conditions:
In Single-Pulse mode, the PWM I/O pin(s) are driven to
the active state when the PTEN bit is set. When the
PWM timer match with the Duty Cycle register occurs,
the PWM I/O pin is driven to the inactive state. When
the PWM timer match with the PTPER register occurs,
the PTMR register is cleared, all active PWM I/O pins
are driven to the inactive state, the PTEN bit is cleared
and an interrupt is generated if the corresponding
interrupt bit is set.
• When the PWM is in Edge-Aligned mode,
synchronization occurs when PTMR is zero.
• When the PWM is in Center-Aligned mode,
synchronization occurs when PTMR is zero and
when the value of PTMR matches PTPER.
Note 1: In the Complementary mode, the even
channel cannot be forced active by a
Fault or override event when the odd
channel is active. The even channel is
always the complement of the odd
channel with dead time inserted, before
the odd channel can be driven to its active
state, as shown in Figure 17-20.
Note:
PTPER and PDCx values are held as they
are after the single-pulse output. To have
another cycle of single pulse, only PTEN
has to be enabled.
17.10 PWM Output Override
2: Dead time is inserted in the PWM
channels even when they are in Override
mode.
The PWM output override bits allow the user to manu-
ally drive the PWM I/O pins to specified logic states,
independent of the duty cycle comparison units. The
PWM override bits are useful when controlling various
types of ECMs like a BLDC motor.
DS39616C-page 202
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 17-20:
PWM OVERRIDE BITS IN COMPLEMENTARY MODE
1
POUT0
POUT1
4
3
5
PWM1
PWM0
2
7
6
Assume: POVD0 = 0; POVD1 = 0; PMOD0 = 0
1. Even override bits have no effect in Complementary mode.
2. Odd override bit is activated, which causes the even PWM to deactivate.
3. Dead-time insertion.
4. Odd PWM activated after the dead time.
5. Odd override bit is deactivated, which causes the odd PWM to deactivate.
6. Dead-time insertion.
7. Even PWM is activated after the dead time.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 203
PIC18F2331/2431/4331/4431
The PWM Duty Cycle registers may be used in con-
17.10.3 OUTPUT OVERRIDE EXAMPLES
junction with the OVDCOND and OVDCONS registers.
The Duty Cycle registers control the average voltage
across the load and the OVDCOND and OVDCONS
registers control the commutation sequence.
Figure 17-22 shows the waveforms, while Table 17-4
and Table 17-5 show the OVDCOND and OVDCONS
register values used to generate the signals.
Figure 17-21 shows an example of a waveform that
might be generated using the PWM output override
feature. The figure shows a six-step commutation
sequence for a BLDC motor. The motor is driven
through a 3-phase inverter as shown in Figure 17-16.
When the appropriate rotor position is detected, the
PWM outputs are switched to the next commutation
state in the sequence. In this example, the PWM out-
puts are driven to specific logic states. The OVDCOND
and OVDCONS register values used to generate the
signals in Figure 17-21 are given in Table 17-4.
REGISTER 17-6: OVDCOND: OUTPUT OVERRIDE CONTROL REGISTER
R/W-1
POVD7(1)
bit 7
R/W-1
POVD6(1)
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
POVD5
POVD4
POVD3
POVD2
POVD1
POVD0
bit 0
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
bit 7-0
POVD7:POVD0: PWM Output Override bits
1= Output on PWM I/O pin is controlled by the value in the Duty Cycle register and the PWM time base
0= Output on PWM I/O pin is controlled by the value in the corresponding POUT bit
Note 1: Unimplemented in PIC18F2331/2431 devices; maintain these bits clear.
REGISTER 17-7: OVDCONS: OUTPUT STATE REGISTER
R/W-0
POUT7(1)
bit 7
R/W-0
POUT6(1)
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
POUT5
POUT4
POUT3
POUT2
POUT1
POUT0
bit 0
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
bit 7-0
POUT7:POUT0: PWM Manual Output bits
1= Output on PWM I/O pin is active when the corresponding PWM output override bit is cleared
0= Output on PWM I/O pin is inactive when the corresponding PWM output override bit is cleared
Note 1: Unimplemented in PIC18F2331/2431 devices; maintain these bits clear.
DS39616C-page 204
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 17-21:
PWM OUTPUT OVERRIDE
EXAMPLE #1
FIGURE 17-22:
PWM OUTPUT OVERRIDE
EXAMPLE #2
1
2
3
4
5
6
1
2
3
4
PWM5
PWM4
PWM3
PWM2
PWM1
PWM0
PWM7
PWM6
PWM5
PWM4
PWM3
PWM2
PWM1
PWM0
TABLE 17-4: PWM OUTPUT OVERRIDE
EXAMPLE #1
State
OVDCOND (POVD) OVDCONS (POUT)
1
2
3
4
5
6
00000000b
00000000b
00000000b
00000000b
00000000b
00000000b
00100100b
00100001b
00001001b
00011000b
00010010b
00000110b
TABLE 17-5: PWM OUTPUT OVERRIDE
EXAMPLE #2
State OVDCOND (POVD) OVDCONS (POUT)
1
2
3
4
11000011b
11110000b
00111100b
00001111b
00000000b
00000000b
00000000b
00000000b
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 205
PIC18F2331/2431/4331/4431
17.11.2 OUTPUT POLARITY CONTROL
17.11 PWM Output and Polarity Control
The polarity of the PWM I/O pins is set during device
programming via the HPOL and LPOL Configuration
bits in the CONFIG3L Configuration register. The
HPOL Configuration bit sets the output polarity for the
high side PWM outputs: PWM1, PWM3, PWM5 and
PWM7. The polarity is active-high when HPOL is
cleared (= 0), and active-low when it is set (= 1).
There are three device Configuration bits associated
with the PWM module that provide PWM output pin
control defined in the CONFIG3L Configuration
register. They are:
• HPOL
• LPOL
• PWMPIN
The LPOL Configuration bit sets the output polarity for
the low side PWM outputs: PWM0, PWM2, PWM4 and
PWM6. As with HPOL, they are active-high when LPOL
is cleared and active-low when it is set.
These three Configuration bits work in conjunction with
the three PWM Enable bits (PWMEN2:PWMEN0) in
the PWMCON0 register. The Configuration bits and
PWM enable bits ensure that the PWM pins are in the
correct states after a device Reset occurs.
All output signals generated by the PWM module are
referenced to the polarity control bits, including those
generated by Fault inputs or manual override (see
Section 17.10 “PWM Output Override”).
17.11.1 OUTPUT PIN CONTROL
The PWMEN2:PWMEN0 control bits enable each
PWM output pin as required in the application.
The default polarity Configuration bits have the PWM
I/O pins in active-high output polarity.
All PWM I/O pins are general purpose I/O. When a pair
of pins are enabled for PWM output, the PORT and
TRIS registers controlling the pins are disabled. Refer
to Figure 17-23 for details.
FIGURE 17-23:
PWM I/O PIN BLOCK DIAGRAM
PWM Signal from Module
1
0
PWM Pin Enable
Data Bus
D
Q
Q
VDD
P
WR PORT
CK
Data Latch
I/O Pin
D
Q
Q
N
WR TRIS
RD TRIS
CK
VSS
TRIS Latch
TTL or
Schmitt
Trigger
Q
D
EN
RD PORT
Note: I/O pin has protection diodes to VDD and VSS. PWM polarity selection logic not shown for clarity.
DS39616C-page 206
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
17.11.3 PWM OUTPUT PIN RESET STATES
17.12.1 FAULT PIN ENABLE BITS
The PWMPIN Configuration bit determines the PWM
output pins to be PWM output pins or digital I/O pins,
after the device comes out of Reset. If the PWMPIN
Configuration bit is unprogrammed (default), the
PWMEN2:PWMEN0 control bits will be cleared on a
device Reset. Consequently, all PWM outputs will be
tri-stated and controlled by the corresponding PORT
and TRIS registers. If the PWMPIN Configuration bit is
programmed low, the PWMEN2:PWMEN0 control bits
will be set, as follows, on a device Reset:
By setting the bits, FLTAEN and FLTBEN in the
FLTCONFIG register, the corresponding Fault inputs
are enabled. If both bits are cleared, then the Fault
inputs have no effect on the PWM module.
17.12.2 MFAULT INPUT MODES
The FLTAMOD and FLTBMOD bits in the FLTCONFIG
register determine the modes of PWM I/O pins that are
deactivated when they are overridden by Fault input.
FLTAS and FLTBS bits in the FLTCONFIG register give
the status of Fault A and Fault B inputs.
• PWMEN2:PWMEN0 = 101if device has 8 PWM
pins (PIC18F4331/4431 devices)
Each of the Fault inputs have two modes of operation:
• PWMEN2:PWMEN0 = 100if device has 6 PWM
pins (PIC18F2331/2431 devices)
• Inactive Mode (FLTxMOD = 0)
This is a Catastrophic Fault Management mode.
When the Fault occurs in this mode, the PWM
outputs are deactivated. The PWM pins will
remain in Inactivate mode until the Fault is
cleared (Fault input is driven high) and the
corresponding Fault Status bit has been cleared
in software. The PWM outputs are enabled
immediately at the beginning of the following
PWM period, after the Fault Status bit (FLTxS) is
cleared.
All PWM pins will be enabled for PWM output and will
have the output polarity defined by the HPOL and
LPOL Configuration bits.
17.12 PWM Fault Inputs
There are two Fault inputs associated with the PWM
module. The main purpose of the input Fault pins is to
disable the PWM output signals and drive them into an
inactive state. The action of the Fault inputs is
performed directly in hardware so that when a Fault
occurs, it can be managed quickly and the PWM
outputs are put into an inactive state to save the power
devices connected to the PWMs.
• Cycle-by-Cycle Mode (FLTxMOD = 1)
When the Fault occurs in this mode, the PWM
outputs are deactivated. The PWM outputs will
remain in the defined Fault states (all PWM out-
puts inactive) for as long as the Fault pin is held
low. After the Fault pin is driven high, the PWM
outputs will return to normal operation at the
beginning of the following PWM period and the
FLTxS bit is automatically cleared.
The PWM Fault inputs are FLTA and FLTB, which can
come from I/O pins, the CPU or another module. The
FLTA and FLTB pins are active-low inputs so it is easy
to “OR” many sources to the same input.
The FLTCONFIG register (Register 17-8) defines the
settings of FLTA and FLTB inputs.
Note:
The inactive state of the PWM pins are
dependent on the HPOL and LPOL Con-
figuration bit settings, which define the
active and inactive state for PWM outputs.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 207
PIC18F2331/2431/4331/4431
17.12.3 PWM OUTPUTS WHILE IN FAULT
CONDITION
17.12.4 PWM OUTPUTS IN DEBUG MODE
The BRFEN bit in the FLTCONFIG register controls the
simulation of a Fault condition, when a breakpoint is hit,
while debugging the application using an In-Circuit
Emulator (ICE) or an In-Circuit Debugger (ICD). Setting
the BRFEN to high, enables the Fault condition on
breakpoint, thus driving the PWM outputs to the
inactive state. This is done to avoid any continuous
keeping of status on the PWM pin, which may result in
damage of the power devices connected to the PWM
outputs.
While in the Fault state (i.e., one or both FLTA and FLTB
inputs are active), the PWM output signals are driven into
their inactive states. The selection of which PWM outputs
are deactivated (while in the Fault state) is determined by
the FLTCON bit in the FLTCONFIG register as follows:
• FLTCON = 1: When FLTA or FLTB is asserted,
the PWM outputs (i.e., PWM<7:0>) are driven into
their inactive state.
• FLTCON = 0: When FLTA or FLTB is asserted, only
PWM<5:0> outputs are driven inactive, leaving
PWM<7:6> activated.
If BRFEN = 0, the Fault condition on breakpoint is
disabled.
Note:
It is highly recommended to enable the
Fault condition on breakpoint if a debugging
tool is used while developing the firmware
and high-power circuitry. When the device is
ready to program after debugging the
firmware, the BRFEN bit can be disabled.
Note:
Disabling only three PWM channels and
leaving one PWM channel enabled when in
the Fault state, allows the flexibility to have
at least one PWM channel enabled. None of
the PWM outputs can be enabled (driven
with the PWM Duty Cycle registers) while
FLTCON = 1 and the Fault condition is
present.
DS39616C-page 208
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 17-8: FLTCONFIG: FAULT CONFIGURATION REGISTER
R/W-0
R/W-0
FLTBS(1)
R/W-0
R/W-0
R/W-0
FLTCON(1)
R/W-0
FLTAS
R/W-0
R/W-0
BRFEN
FLTBMOD(1) FLTBEN(1)
FLTAMOD
FLTAEN
bit 7
bit 0
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
bit 7
bit 6
BRFEN: Breakpoint Fault Enable bit
1= Enable Fault condition on a breakpoint (i.e., only when PWMPIN = 1)
0= Disable Fault condition
FLTBS: Fault B Status bit(1)
1= FLTB is asserted:
if FLTBMOD = 0, cleared by the user;
if FLTBMOD = 1, cleared automatically at beginning of the new period when FLTB is
deasserted
0= No Fault
bit 5
FLTBMOD: Fault B Mode bit(1)
1= Cycle-by-Cycle mode: Pins are inactive for the remainder of the current PWM period or until FLTB
is deasserted; FLTBS is cleared automatically when FLTB is inactive (no Fault present)
0= Inactive mode: Pins are deactivated (catastrophic failure) until FLTB is deasserted and FLTBS is
cleared by the user only
bit 4
bit 3
bit 2
FLTBEN: Fault B Enable bit(1)
1= Enable Fault B
0= Disable Fault B
FLTCON: Fault Configuration bit(2)
1= FLTA, FLTB or both deactivates all PWM outputs
0= FLTA or FLTB deactivates PWM<5:0>
FLTAS: Fault A Status bit
1= FLTA is asserted:
if FLTAMOD = 0, cleared by the user;
if FLTAMOD = 1, cleared automatically at beginning of the new period when FLTA is
deasserted
0= No Fault
bit 1
bit 0
FLTAMOD: Fault A Mode bit
1= Cycle-by-Cycle mode: Pins are inactive for the remainder of the current PWM period or until FLTA is
deasserted; FLTAS is cleared automatically
0= Inactive mode: Pins are deactivated (catastrophic failure) until FLTA is deasserted and FLTAS is
cleared by the user only
FLTAEN: Fault A Enable bit
1= Enable Fault A
0= Disable Fault A
Note 1: Unimplemented in PIC18F2331/2431 devices; maintain these bits clear.
2: PWM<6:7> are implemented only on PIC18F4331/4431 devices. On PIC18F2331/2431 devices, setting or
clearing FLTCON has no effect.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 209
PIC18F2331/2431/4331/4431
The PTMR value for which a Special Event Trigger
17.13 PWM Update Lockout
should occur is loaded into the SEVTCMP register pair.
The SEVTDIR bit in the PWMCON1 register specifies
the counting phase when the PWM time base is in a
Continuous Up/Down Count mode.
For a complex PWM application, the user may need to
write up to four Duty Cycle registers and the PWM Time
Base Period register, PTPER, at a given time. In some
applications, it is important that all buffer registers be
written before the new duty cycle and period values are
loaded for use by the module.
If the SEVTDIR bit is cleared, the Special Event Trigger
will occur on the upward counting cycle of the PWM
time base. If SEVTDIR is set, the Special Event Trigger
will occur on the downward count cycle of the PWM
time base. The SEVTDIR bit has effect only when the
PWM timer is in the Continuous Up/Down Count mode.
A PWM update lockout feature may optionally be
enabled so the user may specify when new duty cycle
buffer values are valid. The PWM update lockout
feature is enabled by setting the control bit, UDIS, in
the PWMCON1 register. This bit affects all Duty Cycle
Buffer registers and the PWM Time Base Period
register, PTPER.
17.14.1 SPECIAL EVENT TRIGGER ENABLE
The PWM module will always produce Special Event
Trigger pulses. This signal may optionally be used by
the A/D module. Refer to Section 20.0 “10-Bit
High-Speed Analog-to-Digital Converter (A/D)
Module” for details.
To perform a PWM update lockout:
1. Set the UDIS bit.
2. Write all Duty Cycle registers and PTPER, if
applicable.
17.14.2 SPECIAL EVENT TRIGGER
POSTSCALER
3. Clear the UDIS bit to re-enable updates.
4. With this, when UDIS bit is cleared, the buffer
values will be loaded to the actual registers. This
makes a synchronous loading of the registers.
The PWM Special Event Trigger has a postscaler that
allows a 1:1 to 1:16 postscale ratio. The postscaler is
configured by writing the SEVOPS3:SEVOPS0 control
bits in the PWMCON1 register.
17.14 PWM Special Event Trigger
The Special Event Trigger output postscaler is cleared
on any write to the SEVTCMP register pair, or on any
device Reset.
The PWM module has a Special Event Trigger capabil-
ity that allows A/D conversions to be synchronized to
the PWM time base. The A/D sampling and conversion
time may be programmed to occur at any point within
the PWM period. The Special Event Trigger allows the
user to minimize the delay between the time when A/D
conversion results are acquired and the time when the
duty cycle value is updated.
The PWM 16-bit Special Event Trigger register,
SEVTCMP (high and low), and five control bits in the
PWMCON1 register are used to control its operation.
DS39616C-page 210
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 17-6: REGISTERS ASSOCIATED WITH THE POWER CONTROL PWM MODULE
Value on
Value on:
POR, BOR
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
all other
Resets
INTCON
GIE/GIEH PEIE/GIEL
TMR0IE
INT0IE
PTIP
PTIE
PTIF
RBIE
TMR0IF
INT0IF
IC1IP
IC1IE
IC1IF
RBIF
0000 000x 0000 000u
IPR3
—
—
—
—
—
—
—
—
IC3DRIP IC2QEIP
IC3DRIE IC2QEIE
TMR5IP ---1 1111 ---1 1111
TMR5IE ---0 0000 ---0 0000
TMR5IF ---0 0000 ---0 0000
PIE3
PIR3
—
IC3DRIF
IC2QEIF
PTCON0
PTCON1
PTOPS3 PTOPS2
PTEN PTDIR
PTOPS1
—
PTOPS0 PTCKPS1 PTCKPS0 PTMOD1 PTMOD0 0000 0000 0000 0000
—
—
—
—
—
00-- ---- 00-- ----
0000 0000 0000 0000
---- 0000 ---- 0000
1111 1111 1111 1111
(1)
PTMRL
PTMRH
PWM Time Base Register (lower 8 bits)
(1)
UNUSED
PWM Time Base Register (upper 4 bits)
(1)
(1)
PTPERL
PWM Time Base Period Register (lower 8 bits)
UNUSED
PTPERH
PWM Time Base Period Register (upper 4 bits) ---- 1111 ---- 1111
(1)
(1)
SEVTCMPL
PWM Special Event Compare Register (lower 8 bits)
0000 0000 0000 0000
SEVTCMPH
UNUSED
PWM Special Event Compare Register
---- 0000 ---- 0000
(upper 4 bits)
(2)
PWMCON0
PWMCON1
DTCON
—
PWMEN2 PWMEN1 PWMEN0 PMOD3
PMOD2
—
PMOD1
UDIS
DT1
PMOD0 -111 0000 -111 0000
OSYNC 0000 0-00 0000 0-00
SEVOPS3 SEVOPS2 SEVOPS1 SEVOPS0 SEVTDIR
DTPS1
BRFEN
DTPS0
DT5
FLTBMOD
POVD5
DT4
DT3
DT2
DT0
0000 0000 0000 0000
(2)
(2)
(2)
FLTCONFIG
OVDCOND
OVDCONS
FLTBS
POVD6
POUT6
FLTBEN
FLTCON
POVD3
POUT3
FLTAS
POVD2
POUT2
FLTAMOD FLTAEN 0000 0000 0000 0000
(2)
(2)
(2)
POVD7
POUT7
POVD4
POUT4
POVD1
POUT1
POVD0 1111 1111 1111 1111
POUT0 0000 0000 0000 0000
0000 0000 0000 0000
--00 0000 --00 0000
0000 0000 0000 0000
--00 0000 --00 0000
0000 0000 0000 0000
--00 0000 --00 0000
0000 0000 0000 0000
--00 0000 --00 0000
(2)
POUT5
(1)
PDC0L
PWM Duty Cycle #0L Register (lower 8 bits)
UNUSED PWM Duty Cycle #0H Register (upper 6 bits)
PWM Duty Cycle #1L register (lower 8 bits)
(1)
PDC0H
(1)
PDC1L
(1)
PDC1H
UNUSED
PWM Duty Cycle #1H Register (upper 6 bits)
(1)
PDC2L
PWM Duty Cycle #2L Register (lower 8 bits)
(1)
PDC2H
UNUSED
PWM Duty Cycle #2H Register (upper 6 bits)
(1,2)
PDC3L
PWM Duty Cycle #3L Register (lower 8 bits)
(1,2)
PDC3H
UNUSED
PWM Duty Cycle #3H Register (upper 6 bits)
Legend:
Note 1:
2:
-= Unimplemented, read as ‘0’, u= unchanged. Shaded cells are not used with the Power Control PWM.
Double-buffered register pairs. Refer to text for explanation of how these registers are read and written to.
Unimplemented in PIC18F2331/2431 devices; maintain these bits clear. Reset values shown are for PIC18F4331/4431 devices.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 211
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 212
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
18.2 SPI Mode
18.0 SYNCHRONOUS SERIAL PORT
(SSP) MODULE
This section contains register definitions and opera-
tional characteristics of the SPI module. Additional
information on the SPI module can be found in the
”PIC® Mid-Range MCU Family Reference Manual”
(DS33023).
18.1 SSP Module Overview
The Synchronous Serial Port (SSP) module is a serial
interface useful for communicating with other periph-
eral or microcontroller devices. These peripheral
devices may be serial EEPROMs, shift registers,
display drivers, A/D Converters, etc. The SSP module
can operate in one of two modes:
SPI mode allows 8 bits of data to be synchronously
transmitted and received simultaneously. To accomplish
communication, typically three pins are used:
• Serial Data Out (SDO) – RC7/RX/DT/SDO or
RD1/SDO
• Serial Peripheral Interface (SPI)
• Inter-Integrated Circuit (I2C™)
An overview of I2C operations and additional
information on the SSP module can be found in the
“PIC® Mid-Range MCU Family Reference Manual”
(DS33023).
• Serial Data In (SDI) – RC4/INT1/SDI/SDA or
RD2/SDI/SDA
• Serial Clock (SCK) – RC5/INT2/SCK/SCL or
RD3/SCK/SCL
Additionally, a fourth pin may be used when in a Slave
mode of operation:
Refer to application note AN578, “Use of the SSP
Module in the I 2C™ Multi-Master Environment”
(DS00578).
• Slave Select (SS) – RC6/TX/CK/SS
When initializing the SPI, several options need to be
specified. This is done by programming the appropriate
control bits in the SSPCON (SSPCON<5:0>) and
SSPSTAT<7:6> registers. 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)
• Clock edge (output data on rising/falling edge of
SCK)
• Clock rate (Master mode only)
• Slave Select mode (Slave mode only)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 213
PIC18F2331/2431/4331/4431
REGISTER 18-1: SSPSTAT: SYNCHRONOUS SERIAL PORT STATUS REGISTER
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
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
bit 7
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 (Microwire)
SPI Slave mode:
SMP must be cleared when SPI is used in Slave mode.
bit 6
CKE: SPI Clock Edge Select bit (Figure 18-2, Figure 18-3 and Figure 18-4)
SPI mode, CKP = 0:
1= Data transmitted on rising edge of SCK (Microwire alternate)
0= Data transmitted on falling edge of SCK
SPI mode, CKP = 1:
1= Data transmitted on falling edge of SCK (Microwire default)
0= Data transmitted on rising edge of SCK
I2C™ mode:
This bit must be maintained clear.
bit 5
bit 4
D/A: Data/Address bit (I2C mode only)
1= Indicates that the last byte received or transmitted was data
0= Indicates that the last byte received or transmitted was address
P: Stop bit (I2C mode only)
This bit is cleared when the SSP module is disabled or when the Start bit is detected last; SSPEN is
cleared.
1= Indicates that a Stop bit has been detected last (this bit is ‘0’ on Reset)
0= Stop bit was not detected last
bit 3
bit 2
S: Start bit (I2C mode only)
This bit is cleared when the SSP module is disabled or when the Stop bit is detected last; SSPEN is
cleared.
1= Indicates that a Start bit has been detected last (this bit is ‘0’ on Reset)
0= Start bit was not detected last
R/W: Read/Write Information bit (I2C mode only)
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 ACK bit.
1= Read
0= Write
bit 1
bit 0
UA: Update Address bit (10-Bit I2C 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
Receive (SPI and I2C modes):
1= Receive complete, SSPBUF is full
0= Receive not complete, SSPBUF is empty
Transmit (I2C mode only):
1= Transmit in progress, SSPBUF is full
0= Transmit complete, SSPBUF is empty
DS39616C-page 214
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 18-2: SSPCON: SYNCHRONOUS SERIAL PORT CONTROL REGISTER
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
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
bit 7
bit 6
WCOL: Write Collision Detect bit
1= The SSPxBUF register is written while it is still transmitting the previous word (must be cleared in
software)
0= No collision
SSPOV: Receive Overflow Indicator bit
In SPI 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. In
Master mode, the overflow bit is not set since each new reception (and transmission) is
initiated by writing to the SSPBUF register.
0= No overflow
In I2C™ mode:
1= A byte is received while the SSPBUF register is still holding the previous byte. SSPOV
is a “don’t care” in Transmit mode. SSPOV must be cleared in software in either mode.
0= No overflow
bit 5
SSPEN: Synchronous Serial Port Enable bit
In SPI mode:
1= Enables serial port and configures SCK, SDO and SDI as serial port pins
0= Disables serial port and configures these pins as I/O port pins
In I2C mode:
1= Enables the serial port and configures the SDA and SCL pins as serial port pins
0= Disables serial port and configures these pins as I/O port pins
In both modes, when enabled, these pins must be properly configured as input or output.
bit 4
CKP: Clock Polarity Select bit
In SPI mode:
1= Idle state for clock is a high level (Microwire default)
0= Idle state for clock is a low level (Microwire alternate)
In I2C mode:
SCK release control.
1= Enable clock
0= Holds clock low (clock stretch). (Used to ensure data setup time.)
bit 3-0
SSPM3:SSPM0: Synchronous Serial Port Mode Select bits
0000= SPI Master mode, clock = FOSC/4
0001= SPI Master mode, clock = FOSC/16
0010= SPI Master mode, clock = FOSC/64
0011= SPI Master mode, clock = TMR2 output/2
0100= SPI Slave mode, clock = SCK pin, SS pin control enabled
0101= SPI Slave mode, clock = SCK pin, SS pin control disabled, SS can be used as I/O pin
0110= I2C Slave mode, 7-bit address
0111= I2C Slave mode, 10-bit address
1011= I2C Firmware Controlled Master mode (slave Idle)
1110= I2C Slave mode, 7-bit address with Start and Stop bit interrupts enabled
1111= I2C Slave mode, 10-bit address with Start and Stop bit interrupts enabled
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 215
PIC18F2331/2431/4331/4431
To enable the serial port, SSP Enable bit, SSPEN
(SSPCON<5>), must be set. To reset or reconfigure
SPI mode, clear bit SSPEN, reinitialize the SSPCON
register and then set bit SSPEN. This configures the
SDI, SDO, SCK and SS pins as serial port pins. For the
pins to behave as the serial port function, they must
have their data direction bits (in the TRISC register)
appropriately programmed. That is:
FIGURE 18-1:
SSP BLOCK DIAGRAM
(SPI MODE)
Internal
Data Bus
Read
Write
SSPBUF Reg
• Serial Data Out (SDO) – RC7/RX/DT/SDO or
RD1/SDO
• SDI must have TRISC<4> or TRISD<2> set
SSPSR Reg
• SDO must have TRISC<7> or TRISD<1> cleared
SDI
Shift
Clock
bit 0
• SCK (Master mode) must have TRISC<5> or
TRISD<3> cleared
SDO
• SCK (Slave mode) must have TRISC<5> or
TRISD<3> set
Peripheral OE
• SS must have TRISA<6> set
Control
Enable
SS
Note 1: When the SPI is in Slave mode with
the
SS
pin
control
enabled
SS
Edge
Select
(SSPCON<3:0> = 0100), the SPI module
will reset if the SS pin is set to VDD.
2
2: If the SPI is used in Slave mode with
CKE = 1, then the SS pin control must be
enabled.
Clock Select
SSPM3:SSPM0
4
TMR2 Output
2
3: When the SPI is in Slave mode with SS pin
control enabled (SSPCON<3:0> = 0100),
the state of the SS pin can affect the state
read back from the TRISC<6> bit. The
peripheral OE signal from the SSP module
into PORTC controls the state that is read
back from the TRISC<6> bit (see
Section 10.3 “PORTC, TRISC and LATC
Registers” for information on PORTC). If
Read-Modify-Write instructions, such as
BSF, are performed on the TRISC register
while the SS pin is high, this will cause the
TRISC<6> bit to be set, thus disabling the
SDO output.
Edge
Select
TCY
Prescaler
4, 16, 64
SCK
TRISC<3>
DS39616C-page 216
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 18-2:
SPI MODE TIMING, MASTER MODE
SCK (CKP = 0,
CKE = 0)
SCK (CKP = 0,
CKE = 1)
SCK (CKP = 1,
CKE = 0)
SCK (CKP = 1,
CKE = 1)
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
bit 0
SDO
SDI (SMP = 0)
bit 7
SDI (SMP = 1)
bit 0
bit 7
SSPIF
FIGURE 18-3:
SPI MODE TIMING (SLAVE MODE WITH CKE = 0)
SS (optional)
SCK (CKP = 0)
SCK (CKP = 1)
SDO
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
SDI (SMP = 0)
bit 0
bit 7
SSPIF
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 217
PIC18F2331/2431/4331/4431
FIGURE 18-4:
SPI MODE TIMING (SLAVE MODE WITH CKE = 1)
SS
SCK (CKP = 0)
SCK (CKP = 1)
SDO
bit 2
bit 7
bit 6
bit 5
bit 4
bit 3
bit 1
bit 0
SDI (SMP = 0)
bit 0
bit 7
SSPIF
TABLE 18-1: REGISTERS ASSOCIATED WITH SPI OPERATION
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1
Value on
all other
Resets
Value on:
POR, BOR
Bit 0
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF
RBIF 0000 000x 0000 000u
PIR1
—
—
ADIF
ADIE
RCIF
RCIE
TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
1111 1111 1111 1111
PIE1
TRISC
PORTC Data Direction Register
SSPBUF SSP Receive Buffer/Transmit Register
xxxx xxxx uuuu uuuu
SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000
TRISA
TRISA7(1) TRISA6(2) PORTA Data Direction Register
SMP CKE D/A R/W
1111 1111 1111 1111
0000 0000 0000 0000
SSPSTAT
P
S
UA
BF
Legend: x= unknown, u= unchanged, -= unimplemented, read as ‘0’. Shaded cells are not used by the SSP in
SPI mode.
Note 1: RA7 and associated bits are configured as port pins in INTIO2 Oscillator mode only and read ‘0’ in all other
modes.
2: RA6 and associated bits are configured as port pins in RCIO, ECIO and INTIO2 (with port function on RA6)
Oscillator mode only and read ‘0’ in all other oscillator modes.
DS39616C-page 218
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
The SSPCON register allows control of the I2C opera-
tion. Four mode selection bits (SSPCON<3:0>) allow
2
18.3 SSP I C Operation
The SSP module, in I2C mode, fully implements all slave
functions except general call support and provides
interrupts on Start and Stop bits in hardware to facilitate
firmware implementations of the master functions. The
SSP module implements the standard mode
specifications, as well as 7-bit and 10-bit addressing.
one of the following I2C modes to be selected:
• I2C Slave mode (7-bit address)
• I2C Slave mode (10-bit address)
• I2C Slave mode (7-bit address), with Start and
Stop bit interrupts enabled to support Firmware
Controlled Master mode
• I2C Slave mode (10-bit address), with Start and
Stop bit interrupts enabled to support Firmware
Controlled Master mode
• I2C Start and Stop bit interrupts enabled to
support Firmware Controlled Master mode;
Slave is Idle
Two pins are used for data transfer. These are the SCK/
SCL pin, which is the clock (SCL), and the SDI/SDA
pin, which is the data (SDA). The user must configure
these pins as inputs or outputs through the
TRISC<5:4> or TRISD<3:2> bits.
The SSP module functions are enabled by setting SSP
Enable bit SSPEN (SSPCON<5>).
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 as inputs by
setting the appropriate TRISC or TRISD bits. Pull-up
resistors must be provided externally to the SCL and
SDA pins for proper operation of the I2C module.
FIGURE 18-5:
SSP BLOCK DIAGRAM
(I2C™ MODE)
Internal
Data Bus
Additional information on SSP I2C operation can be
found in the “PIC® Mid-Range MCU Family Reference
Manual” (DS33023).
Read
Write
SSPBUF Reg
SCK/SCL(1)
SDI/SDA(1)
18.3.1
SLAVE MODE
Shift
Clock
In Slave mode, the SCL and SDA pins must be config-
ured as inputs (TRISC<5:4> or TRISD<3:2> set). The
SSP module will override the input state with the output
data when required (slave-transmitter).
SSPSR Reg
MSb
LSb
Addr Match
Match Detect
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
then load the SSPBUF register with the received value
currently in the SSPSR register.
SSPADD Reg
Set, Reset
S, P bits
(SSPSTAT Reg)
Start and
Stop bit Detect
There are certain conditions that will cause the SSP
module not to give this ACK pulse. They include (either
or both):
Note 1: When SSPMX = 1in CONFIG3H:
SCK/SCL is multiplexed to pin RC5, SDA/SDI
is multiplexed to pin RC4 and SDO is
multiplexed to pin RC7.
a) The Buffer Full bit, BF (SSPSTAT<0>), was set
before the transfer was received.
b) The SSP Overflow bit, SSPOV (SSPCON<6>),
was set before the transfer was received.
When SSPMX = 0in CONFIG3H:
SCK/SCL is multiplexed to pin RD3, SDA/SDI
is multiplexed to pin RD2 and SDO is
multiplexed to pin RD1.
In this case, the SSPSR register value is not loaded
into the SSPBUF, but bit SSPIF (PIR1<3>) is set.
Table 18-2 shows what happens when a data transfer
byte is received, given the status of bits BF and
SSPOV. The shaded cells show the condition where
user software did not properly clear the overflow
condition. Flag bit, BF, is cleared by reading the
SSPBUF register, while bit SSPOV is cleared through
software.
The SSP module has five registers for I2C operation.
These are the:
• SSP Control Register (SSPCON)
• SSP Status Register (SSPSTAT)
• Serial Receive/Transmit Buffer (SSPBUF)
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 requirements of the
SSP module, are shown in timing parameter 100 and
parameter 101.
• SSP Shift Register (SSPSR) – Not directly
accessible
• SSP Address Register (SSPADD)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 219
PIC18F2331/2431/4331/4431
The sequence of events for 10-Bit Addressing mode is
as follows, with steps 7-9 for slave-transmitter:
18.3.1.1
Addressing
Once the SSP 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 incom-
ing 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:
1. Receive first (high) byte of address (bits SSPIF,
BF and bit UA 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.
4. Receive second (low) byte of address (bits
SSPIF, BF and UA are set).
a) The SSPSR register value is loaded into the
SSPBUF register.
5. Update the SSPADD register with the first (high)
byte of address. If match releases SCL line, this
will clear bit UA.
b) The Buffer Full bit, BF, is set.
c) An ACK pulse is generated.
6. Read the SSPBUF register (clears bit BF) and
clear flag bit SSPIF.
d) SSP Interrupt Flag bit, SSPIF (PIR1<3>), is set
(interrupt is generated if enabled) on the falling
edge of the ninth SCL pulse.
7. Receive Repeated Start condition.
8. Receive first (high) byte of address (bits SSPIF
and BF are set).
In 10-Bit Addressing mode, two address bytes need to
be received by the slave (Figure 18-7). 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 ‘1111 0 A9 A8 0’, where A9and
A8are the two MSbs of the address.
9. Read the SSPBUF register (clears bit BF) and
clear flag bit SSPIF.
TABLE 18-2: DATA TRANSFER RECEIVED BYTE ACTIONS
Status Bits as Data
Set SSPIF Bit
(SSP interrupt occurs
if enabled)
Generate ACK
Transfer is Received
SSPSR → SSPBUF
Pulse
BF
SSPOV
0
1
1
0
0
0
1
1
Yes
No
No
No
Yes
No
No
No
Yes
Yes
Yes
Yes
Note: Shaded cells show the conditions where the user software did not properly clear the overflow condition.
DS39616C-page 220
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
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 (SSPCON<6>) is set. This is an error
condition due to the user’s firmware.
18.3.1.2
Reception
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.
An SSP 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.
FIGURE 18-6:
I2C™ WAVEFORMS FOR RECEPTION (7-BIT ADDRESS)
R/W = 0
Receiving Address
Receiving Data
Receiving Data
ACK
ACK
9
ACK
SDA
SCL
A7 A6 A5 A4 A3 A2 A1
D1 D0
D7 D6 D5 D4 D3 D2
D7 D6 D5 D4 D3 D2 D1 D0
3
7
7
1
2
4
8
9
5
7
8
3
6
9
5
6
1
2
3
6
1
2
4
8
4
5
P
S
Cleared in software
SSPIF (PIR1<3>)
Bus master
terminates
transfer
BF (SSPSTAT<0>)
SSPOV (SSPCON<6>)
SSPBUF register is read
Bit SSPOV is set because the SSPBUF register is still full
ACK is not sent
An SSP interrupt is generated for each data transfer
byte. Flag bit, SSPIF, must be cleared in software and
the SSPSTAT register is used to determine the status
of the byte. Flag bit, SSPIF, is set on the falling edge of
the ninth clock pulse.
18.3.1.3
Transmission
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 SCK/SCL is held low.
The transmit data must be loaded into the SSPBUF
register, which also loads the SSPSR register. Then,
pin SCK/SCL should be enabled by setting bit CKP
(SSPCON<4>). The master must monitor the SCL pin
prior to asserting another clock pulse. The slave
devices may be holding off the master by stretching the
clock. 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 18-7).
As a slave-transmitter, the ACK pulse from the master-
receiver is latched on the rising edge of the ninth SCL
input pulse. If the SDA line was high (not ACK), then the
data transfer is complete. When the ACK is latched by
the slave, the slave logic is reset (resets SSPSTAT
register) and the slave then monitors for another
occurrence of the Start bit. If the SDA line was low (ACK),
the transmit data must be loaded into the SSPBUF
register, which also loads the SSPSR register. Then pin
SCK/SCL should be enabled by setting bit CKP.
FIGURE 18-7:
I2C™ WAVEFORMS FOR TRANSMISSION (7-BIT ADDRESS)
Receiving Address
R/W = 1
ACK
Transmitting Data
ACK
9
SDA
A7 A6 A5 A4 A3 A2 A1
D7 D6 D5 D4 D3 D2 D1 D0
SCL
S
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
P
SCL held low
while CPU
responds to SSPIF
Data in
sampled
Cleared in software
SSPIF (PIR1<3>)
BF (SSPSTAT<0>)
CKP (SSPCON<4>)
From SSP Interrupt
Service Routine
SSPBUF is written in software
Set bit after writing to SSPBUF
(the SSPBUF must be written to
before the CKP bit can be set)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 221
PIC18F2331/2431/4331/4431
18.3.2
MASTER MODE
18.3.3
MULTI-MASTER MODE
Master mode of operation is supported in firmware
using interrupt generation on the detection of the Start
and Stop conditions. The Stop (P) and Start (S) bits are
cleared from a Reset or when the SSP module is
disabled. The Stop (P) and Start (S) bits will toggle
based on the Start and Stop conditions. Control of the
I2C bus may be taken when the P bit is set, or the bus
is Idle and both the S and P bits are clear.
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 SSP
module is disabled. The Stop (P) and Start (S) bits will
toggle based on the Start and Stop conditions. Control
of the I2C bus may be taken when bit P (SSPSTAT<4>)
is set, or the bus is Idle and 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.
In Master mode, the SCL and SDA lines are manipu-
lated by clearing the corresponding TRISC<5:4> or
TRISD<3:2> bits. The output level is always low,
regardless of the value(s) in PORTC<5:4> or
PORTD<3:2>. So when transmitting data, a ‘1’ data bit
must have the TRISC<4> bit set (input) and a ‘0’ data
bit must have the TRISC<4> bit cleared (output). The
same scenario is true for the SCL line with the
TRISC<4> or TRISD<2> bit. Pull-up resistors must be
provided externally to the SCL and SDA pins for proper
operation of the I2C module.
In Multi-Master mode, the SDA line must be monitored
to see if the signal level is the expected output level.
This check only needs to be done when a high level is
output. If a high level is expected and a low level is
present, the device needs to release the SDA and SCL
lines (set TRISC<5:4> or TRISD<3:2>). There are two
stages where this arbitration can be lost, these are:
• Address Transfer
• Data Transfer
The following events will cause SSP Interrupt Flag bit,
SSPIF, to be set (SSP interrupt will occur if enabled):
When the slave logic is enabled, the slave continues to
receive. If arbitration was lost during the address
transfer stage, communication to the device may be in
progress. If addressed, an ACK pulse will be gener-
ated. If arbitration was lost during the data transfer
stage, the device will need to retransfer the data at a
later time.
• Start condition
• Stop condition
• Data transfer byte transmitted/received
Master mode of operation can be done with either the
Slave mode Idle (SSPM3:SSPM0 = 1011) or with the
Slave active. When both Master and Slave modes are
enabled, the software needs to differentiate the
source(s) of the interrupt.
TABLE 18-3: REGISTERS ASSOCIATED WITH I2C™ OPERATION
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1
Value on
all other
Resets
Value on:
POR, BOR
Bit 0
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
PIR1
PIE1
—
—
ADIF
ADIE
RCIF
RCIE
TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
SSPBUF SSP Receive Buffer/Transmit Register
SSPADD SSP Address Register (I2C mode)
xxxx xxxx uuuu uuuu
0000 0000 0000 0000
SSPCON
WCOL
SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000
SSPSTAT SMP(1)
TRISC(2) PORTC Data Direction Register
TRISD(2) PORTD Data Direction Register
CKE(1)
D/A
P
S
R/W
UA
BF
0000 0000 0000 0000
1111 1111 1111 1111
1111 1111 1111 1111
Legend: x= unknown, u= unchanged, -= unimplemented, read as ‘0’. Shaded cells are not used by the SSP
module in I2C mode.
Note 1: Maintain these bits clear in I2C mode.
2: Depending upon the setting of SSPMX in CONFIG3H, these pins are multiplexed to PORTC or PORTD.
DS39616C-page 222
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
The operation of the Enhanced USART module is
controlled through three registers:
19.0 ENHANCED UNIVERSAL
SYNCHRONOUS
• Transmit Status and Control (TXSTA)
ASYNCHRONOUS RECEIVER
TRANSMITTER (EUSART)
• Receive Status and Control (RCSTA)
• Baud Rate Control (BAUDCTL)
The Enhanced Universal Synchronous Asynchronous
Receiver Transmitter (EUSART) module is one of the
two serial I/O modules available in the PIC18F2331/
2431/4331/4431 family of microcontrollers. EUSART is
also known as a Serial Communications Interface or
SCI.
These are detailed on the following pages in
Register 19-1, Register 19-2 and Register 19-3,
respectively.
19.1 Asynchronous Operation in
Power-Managed Modes
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.
The EUSART may operate in Asynchronous mode
while the peripheral clocks are being provided by the
internal oscillator block. This makes it possible to
remove the crystal or resonator that is commonly con-
nected as the primary clock on the OSC1 and OSC2
pins.
The EUSART module implements additional features,
including automatic baud rate detection and
calibration, automatic wake-up on Sync Break
reception and 12-bit Break character transmit. These
features make it ideally suited for use in Local
Interconnect Network (LIN) bus systems.
The factory calibrates the internal oscillator block out-
put (INTOSC) for 8 MHz (see Table 25-6). However,
this frequency may drift as VDD or temperature
changes, and this directly affects the asynchronous
baud rate. Two methods may be used to adjust the
baud rate clock, but both require a reference clock
source of some kind.
The EUSART can be configured in the following
modes:
The first (preferred) method uses the OSCTUNE
register to adjust the INTOSC output back to 8 MHz.
Adjusting the value in the OSCTUNE register allows for
fine resolution changes to the system clock source (see
Section 3.6 “INTOSC Frequency Drift” for more
information).
• 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
The other method adjusts the value in the Baud Rate
Generator (BRG). There may not be fine enough
resolution when adjusting the Baud Rate Generator to
compensate for a gradual change in the peripheral
clock frequency.
• Synchronous – Slave (half-duplex) with selectable
clock polarity
In order to configure pins RC6/TX/CK/SS and RC7/RX/
DT/SDO as the Enhanced Universal Synchronous
Asynchronous Receiver Transmitter:
• SPEN (RCSTA<7>) bit must be set ( = 1),
• TRISC<6> bit must be set ( = 1), and
• TRISC<7> bit must be set ( = 1).
Note:
The EUSART control will automatically
reconfigure the pin from input to output as
needed.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 223
PIC18F2331/2431/4331/4431
REGISTER 19-1: TXSTA: TRANSMIT STATUS AND CONTROL REGISTER
R/W-0
CSRC
R/W-0
TX9
R/W-0
TXEN(1)
R/W-0
SYNC
R/W-0
R/W-0
BRGH
R-1
R/W-0
TX9D
SENDB
TRMT
bit 7
bit 0
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
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)
1= Transmit enabled
0= Transmit disabled
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.
Note 1: SREN/CREN overrides TXEN in Sync mode.
DS39616C-page 224
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 19-2: 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
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
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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 225
PIC18F2331/2431/4331/4431
REGISTER 19-3: BAUDCTL: BAUD RATE CONTROL REGISTER
U-0
—
R-1
U-0
—
R/W-1
SCKP
R/W-0
U-0
—
R/W-0
WUE
R/W-0
RCIDL
BRG16
ABDEN
bit 7
bit 0
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
bit 7
bit 6
Unimplemented: Read as ‘0’
RCIDL: Receive Operation Idle Status bit
1= Receiver is Idle
0= Receive in progress
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.
DS39616C-page 226
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
19.2.1
POWER-MANAGED MODE
OPERATION
19.2 EUSART Baud Rate Generator
(BRG)
The system clock is used to generate the desired baud
rate. However, when a power-managed mode is
entered, the clock source may be operating at a
different frequency than in PRI_RUN mode. In Sleep
mode, no clocks are present and in PRI_IDLE, the
primary clock source continues to provide clocks to the
Baud Rate Generator. However, in other power-
managed modes, the clock frequency will probably
change. This may require the value in SPBRG to be
adjusted.
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 (BAUDCTL<3>)
selects 16-bit mode.
The SPBRGH:SPBRG register pair controls the period
of a free-running timer. In Asynchronous mode, bits
BRGH (TXSTA<2>) and BRG16 also control the baud
rate. In Synchronous mode, bit BRGH is ignored.
Table 19-1 shows the formula for computation of the
baud rate for different EUSART modes, which only
apply in Master mode (internally generated clock).
If the system clock is changed during an active receive
operation, a receive error or data loss may result. To
avoid this problem, check the status of the RCIDL bit
and make sure that the receive operation is Idle before
changing the system clock.
Given the desired baud rate and FOSC, the nearest
integer value for the SPBRGH:SPBRG registers can be
calculated using the formulas in Table 19-1. From this,
the error in baud rate can be determined. An example
calculation is shown in Example 19-1. Typical baud
rates and error values for the various Asynchronous
modes are shown in Table 19-2. It may be
advantageous to use the high baud rate (BRGH = 1),
or the 16-bit BRG, to reduce the baud rate error or
achieve a slow baud rate for a fast oscillator frequency.
19.2.2
SAMPLING
The data on the RC7/RX/DT/SDO 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.
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.
TABLE 19-1: 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
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 227
PIC18F2331/2431/4331/4431
EXAMPLE 19-1:
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
Calculated Baud Rate = 16000000/(64 (25 + 1))
= 9615
Error
= (Calculated Baud Rate – Desired Baud Rate)/Desired Baud Rate
= (9615 – 9600)/9600 = 0.16%
TABLE 19-2: REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR
Value on
POR, BOR
Value on all
other Resets
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TXSTA
CSRC
SPEN
—
TX9
RX9
TXEN
SREN
—
SYNC
SENDB BRGH
TRMT
OERR
TX9D
RX9D
0000 0010
0000 000x
0000 0010
0000 000x
-1-1 0-00
0000 0000
0000 0000
RCSTA
CREN ADDEN
SCKP BRG16
FERR
—
BAUDCTL
RCIDL
WUE ABDEN -1-1 0-00
0000 0000
SPBRGH EUSART Baud Rate Generator Register High Byte
SPBRG EUSART Baud Rate Generator Register Low Byte
0000 0000
Legend: x= unknown, -= unimplemented, read as ‘0’. Shaded cells are not used by the BRG.
TABLE 19-3: 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
value
(decimal)
SPBRG Actual
value
(decimal)
SPBRG
value
%
%
Error
%
Error
%
Error
Rate
(K)
Rate
(K)
Rate
(K)
Error
(decimal)
(decimal)
0.3
1.2
—
—
—
—
—
—
—
255
129
31
15
4
—
—
—
129
64
15
7
—
1.201
2.403
9.615
—
—
-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
0.300
1.201
2.403
—
-0.16
-0.16
-0.16
—
103
25
12
—
0.300
1.201
—
-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
—
—
—
—
—
DS39616C-page 228
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 19-3: BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED)
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
SPBRG Actual
SPBRG Actual
value
(decimal)
SPBRG
value
(decimal)
%
%
Error
%
Error
%
Error
Rate
(K)
value
Rate
(K)
Rate
(K)
Error
(decimal)
(decimal)
2.4
9.6
—
—
—
255
129
42
—
—
—
129
64
2.441
9.615
1.73
0.16
1.73
-1.36
8.51
255
64
31
10
4
2.403
9.615
19.230
55.555
—
-0.16
-0.16
-0.16
3.55
—
207
51
25
8
9.766
1.73
0.16
0.94
-1.36
9.615
0.16
0.16
-1.36
-1.36
19.2
57.6
115.2
19.231
58.140
113.636
19.231
56.818
113.636
19.531
56.818
125.000
21
21
10
—
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
—
1.201
2.403
9.615
—
—
-0.16
-0.16
-0.16
—
—
103
51
12
—
0.300
1.201
2.403
—
-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
—
—
—
—
—
—
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
(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
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
0.300
1.201
2.403
9.615
19.230
55.555
—
-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
0.300
1.201
2.403
9.615
—
-0.16
-0.16
-0.16
-0.16
—
415
103
51
12
—
0.300
1.201
2.403
—
-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
—
—
—
—
—
—
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 229
PIC18F2331/2431/4331/4431
TABLE 19-3: BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED)
SYNC = 0, BRGH = 1, BRG16 = 1or SYNC = 1, 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
0.00
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
0.300
1.200
-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
2.400
9.6
9.606
9.596
9.615
9.615
19.2
57.6
115.2
19.193
57.803
114.943
19.231
57.471
116.279
19.231
58.140
113.636
19.230
57.142
117.647
172
86
42
21
-2.12
16
SYNC = 0, BRGH = 1, BRG16 = 1or 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
0.300
1.201
2.403
9.615
19.230
55.555
—
-0.04
-0.16
-0.16
-0.16
-0.16
3.55
—
1665
415
207
51
0.300
1.201
2.403
9.615
19.230
—
-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
—
—
—
—
DS39616C-page 230
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
carry occurred for 8-bit modes by checking for 00h in
the SPBRGH register. Refer to Table 19-4 for counter
clock rates to the BRG.
19.2.3
AUTO-BAUD RATE DETECT
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.
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. RCREG content should be discarded.
The automatic baud rate measurement sequence
(Figure 19-1) begins whenever a Start bit is received and
the ABDEN bit is set. The calculation is self-averaging.
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
(see Section 19.3.4 “Auto-Wake-up on
Sync Break Character”).
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.
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.
Once the ABDEN bit is set, the state machine will clear
the BRG and look for a Start bit. The Auto-Baud Detect
must receive a byte with the value of 55h (ASCII “U”,
which is also the LIN bus Sync character) in order to
calculate the proper bit rate. The measurement takes
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 registers.
Once the 5th edge is seen (should correspond to the
Stop bit), the ABDEN bit is automatically cleared.
TABLE 19-4: BRG COUNTER CLOCK
RATES
BRG16 BRGH
BRG Counter Clock
0
0
1
0
1
FOSC/512
FOSC/256
FOSC/128
FOSC/32
0
1
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
1
Note:
During the ABD sequence, SPBRG and
SPBRGH are both used as a 16-bit counter,
independent of the BRG16 setting.
FIGURE 19-1:
AUTOMATIC BAUD RATE CALCULATION
BRG Value
XXXXh
0000h
001Ch
Edge #2
Bit 3
Edge #3
Bit 5
Edge #4
Bit 7
Bit 6
Edge #5
Stop Bit
Edge #1
Bit 1
Start
Bit 2
Bit 4
RX Pin
Bit 0
BRG Clock
Auto-Cleared
Set by user
ABDEN bit
RCIF bit
(Interrupt)
Read
RCREG
XXXXh
XXXXh
1Ch
00h
SPBRG
SPBRGH
Note 1: The ABD sequence requires the EUSART module to be configured in Asynchronous mode and WUE = 0.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 231
PIC18F2331/2431/4331/4431
Once the TXREG register transfers the data to the TSR
19.3 EUSART Asynchronous Mode
register (occurs in one TCY), the TXREG register is
empty and flag bit, TXIF (PIR1<4>), is set. This inter-
rupt can be enabled/disabled by setting/clearing
enable bit, TXIE (PIE1<4>). Flag bit TXIF will be set,
regardless of the state of enable bit TXIE and cannot be
cleared in software. Flag bit TXIF is not cleared
immediately upon loading the Transmit Buffer register,
TXREG. TXIF 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 BAUDCTL<3>). Parity
is not supported by the hardware but can be
implemented in software and stored as the 9th data bit.
While flag bit, TXIF, indicates the status of the TXREG
register, another bit, TRMT (TXSTA<1>), shows the
status of the TSR register. Status bit, 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.
Asynchronous mode is available in all low-power
modes; it is available in Sleep mode only when Auto-
Wake-up on Sync Break is enabled. When in PRI_IDLE
mode, no changes to the Baud Rate Generator values
are required; however, other low-power mode clocks
may operate at another frequency than the primary
clock. Therefore, the Baud Rate Generator values may
need to be adjusted.
Note 1: The TSR register is not mapped in data
memory, so it is not available to the user.
2: Flag bit TXIF is set when enable bit TXEN
is set.
To set up an Asynchronous Transmission:
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.
When operating in Asynchronous mode, the EUSART
module consists of the following important elements:
• Baud Rate Generator
• Sampling Circuit
2. Enable the asynchronous serial port by clearing
bit, SYNC, and setting bit, SPEN.
• Asynchronous Transmitter
• Asynchronous Receiver
3. If interrupts are desired, set enable bit, TXIE.
• Auto-Wake-up on Sync Break Character
• 12-Bit Break Character Transmit
• Auto-Baud Rate Detection
4. If 9-bit transmission is desired, set transmit bit,
TX9. Can be used as address/data bit.
5. Enable the transmission by setting bit, TXEN,
which will also set bit, TXIF.
19.3.1
EUSART ASYNCHRONOUS
TRANSMITTER
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).
The EUSART transmitter block diagram is shown in
Figure 19-2. 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).
If using interrupts, ensure that the GIE and PEIE bits in
the INTCON register (INTCON<7:6>) are set.
DS39616C-page 232
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 19-2:
EUSART TRANSMIT BLOCK DIAGRAM
Data Bus
TXREG Register
TXIF
TXIE
8
MSb
(8)
LSb
0
Pin Buffer
and Control
•
• •
TSR Register
RC6/TX/CK/SS Pin
Interrupt
Baud Rate CLK
SPBRG
TXEN
TRMT
SPEN
BRG16
SPBRGH
TX9
Baud Rate Generator
TX9D
FIGURE 19-3:
ASYNCHRONOUS TRANSMISSION
Write to TXREG
Word 1
BRG Output
(Shift Clock)
RC6/TX/CK/SS
(pin)
Start bit
bit 0
bit 1
Word 1
bit 7/8
Stop bit
TXIF bit
(Interrupt Reg. Flag)
1 TCY
Word 1
Transmit Shift Reg
TRMT bit
(Transmit Shift
Reg. Empty Flag)
FIGURE 19-4:
ASYNCHRONOUS TRANSMISSION (BACK TO BACK)
Write to TXREG
Word 2
Start bit
Word 1
BRG Output
(Shift Clock)
RC6/TX/CK/SS
(pin)
Start bit
Word 2
bit 0
bit 1
Word 1
bit 7/8
bit 0
Stop bit
1 TCY
TXIF bit
(Interrupt Reg. Flag)
1 TCY
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Word 2
Transmit Shift Reg.
Word 1
Transmit Shift Reg.
Note:
This timing diagram shows two consecutive transmissions.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 233
PIC18F2331/2431/4331/4431
TABLE 19-5: REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION
Value on
all other
Resets
Value on
POR, BOR
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
RBIE
TMR0IF INT0IF
RBIF
0000 000x 0000 000u
-000 0000 -000 0000
-000 0000 -000 0000
-111 1111 -111 1111
0000 000x 0000 000x
0000 0000 0000 0000
0000 0010 0000 0010
-1-1 0-00 -1-1 0-00
0000 0000 0000 0000
0000 0000 0000 0000
—
—
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
TXIF
TXIE
TXIP
SSPIF CCP1IF TMR2IF TMR1IF
SSPIE CCP1IE TMR2IE TMR1IE
SSPIP CCP1IP TMR2IP TMR1IP
PIE1
IPR1
—
RCSTA
TXREG
TXSTA
BAUDCTL
SPEN
CREN ADDEN
FERR
OERR
RX9D
EUSART Transmit Register
CSRC
—
TX9
TXEN
—
SYNC SENDB BRGH
SCKP BRG16
TRMT
WUE
TX9D
RCIDL
—
ABDEN
SPBRGH EUSART Baud Rate Generator Register High Byte
SPBRG
EUSART Baud Rate Generator Register Low Byte
x= unknown, -= unimplemented, read as ‘0’. Shaded cells are not used for asynchronous transmission.
Legend:
DS39616C-page 234
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
19.3.2
EUSART ASYNCHRONOUS
RECEIVER
19.3.3
SETTING UP 9-BIT MODE WITH
ADDRESS DETECT
The receiver block diagram is shown in Figure 19-5.
The data is received on the RC7/RX/DT/SDO 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 com-
plete. The interrupt will be Acknowledged if the
RCIE and GIE bits are set.
6. Flag bit, RCIF, will be set when reception is com-
plete 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 19-5:
EUSART RECEIVE BLOCK DIAGRAM
CREN
OERR
FERR
x64 Baud Rate CLK
SPBRGH
÷ 64
RSR Register
• • •
MSb
Stop
LSb
BRG16
SPBRG
or
÷ 16
Start
(8)
7
1
0
or
Baud Rate Generator
÷ 4
RX9
Pin Buffer
and Control
Data
Recovery
RX9D
RCREG Register
RC7/RX/DT/SDO
FIFO
SPEN
8
RCIF
RCIE
Interrupt
Data Bus
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 235
PIC18F2331/2431/4331/4431
To set up an Asynchronous Transmission:
5. Enable the transmission by setting bit, TXEN,
which will also set bit, TXIF.
1. Initialize the SPBRG register for the appropriate
baud rate. If a high-speed baud rate is desired,
set bit, BRGH (see Section 19.2 “EUSART
Baud Rate Generator (BRG)”).
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).
2. Enable the asynchronous serial port by clearing
bit, SYNC, and setting bit, SPEN.
If using interrupts, ensure that the GIE and PEIE bits in
the INTCON register (INTCON<7:6>) are set.
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.
FIGURE 19-6:
ASYNCHRONOUS RECEPTION
Start
bit
Start
bit
Start
bit
Stop
bit
Stop
bit
Stop
bit
bit 0 bit 1
bit 7/8
bit 7/8
bit 7/8
RX (Pin)
bit 0
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 19-6: REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
Value on
all other
Resets
Value on
POR, BOR
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
RBIE
TMR0IF INT0IF
RBIF
0000 000x
0000 000u
-000 0000
-000 0000
-111 1111
0000 000x
0000 0000
0000 0010
-1-1 0-00
0000 0000
0000 0000
—
—
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
TXIF
TXIE
TXIP
SSPIF CCP1IF TMR2IF TMR1IF -000 0000
SSPIE CCP1IE TMR2IE TMR1IE -000 0000
SSPIP CCP1IP TMR2IP TMR1IP -111 1111
PIE1
IPR1
—
RCSTA
RCREG
TXSTA
BAUDCTL
SPEN
CREN ADDEN FERR
OERR
RX9D
0000 000x
0000 0000
0000 0010
EUSART Receive Register
CSRC
—
TX9
TXEN
—
SYNC SENDB BRGH
TRMT
WUE
TX9D
RCIDL
SCKP BRG16
—
ABDEN -1-1 0-00
0000 0000
SPBRGH EUSART Baud Rate Generator Register High Byte
SPBRG
EUSART Baud Rate Generator Register Low Byte
0000 0000
Legend:
x= unknown, -= unimplemented, read as ‘0’. Shaded cells are not used for asynchronous reception.
DS39616C-page 236
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
and cause data or framing errors. To work properly,
therefore, the initial characters in the transmission must
be all ‘0’s. This can be 00h (8 bytes) for standard RS-232
devices, or 000h (12 bits) for LIN bus.
19.3.4
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.
Oscillator start-up time must also be considered,
especially in applications using oscillators with longer
start-up intervals (i.e., LP, XT or HS/PLL mode). The
Sync Break (or Wake-up Signal) character must be of
sufficient length, and be followed by a sufficient inter-
val, to allow enough time for the selected oscillator to
start and provide proper initialization of the EUSART.
The auto-wake-up feature is enabled by setting the
WUE bit (BAUDCTL<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.)
19.3.4.2
Special Considerations Using the
WUE Bit
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.
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 19-7), and asynchronously if the device is in
Sleep mode (Figure 19-8). The interrupt condition is
cleared by reading the RCREG register.
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 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.
19.3.4.1
Special Considerations Using
Auto-Wake-up
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
FIGURE 19-7:
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
OSC1
Auto-Cleared
Bit set by user
WUE bit
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 19-8:
AUTO-WAKE-UP BIT (WUE) TIMINGS DURING SLEEP
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
OSC1
Auto-Cleared
Bit set by user
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 while the stposc signal is still active.
This sequence should not depend on the presence of Q clocks.
2: The EUSART remains in Idle while the WUE bit is set.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 237
PIC18F2331/2431/4331/4431
19.3.5
BREAK CHARACTER SEQUENCE
19.3.5.1
Break and Sync Transmit Sequence
The Enhanced USART module has the capability of
sending the special Break character sequences that
are required by the LIN bus standard. The Break char-
acter 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.
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.
1. Configure the EUSART for the desired mode.
2. Set the TXEN and SENDB bits to setup the
Break character.
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.
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).
5. After the Break has been sent, the SENDB bit is
reset by hardware. The Sync character now
transmits in the preconfigured mode.
When the TXREG becomes empty, as indicated by the
TXIF, the next data byte can be written to TXREG.
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.
19.3.6
RECEIVING A BREAK CHARACTER
The Enhanced USART module can receive a Break
character in two ways.
The TRMT bit indicates when the transmit operation is
active or Idle, just as it does during normal transmis-
sion. See Figure 19-9 for the timing of the Break
character sequence.
The first method forces configuration of the baud rate
at a frequency of 9/13 of the typical speed. This allows
for the Stop bit transition to be at the correct sampling
location (13 bits for Break versus Start bit and 8 data
bits for typical data).
The second method uses the auto-wake-up feature
described in Section 19.3.4 “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.
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
before placing the EUSART in its Sleep mode.
FIGURE 19-9:
SEND BREAK CHARACTER SEQUENCE
Write to TXREG
Dummy Write
BRG Output
(Shift Clock)
Start Bit
TX (Pin)
Bit 0
Bit 1
Break
Bit 11
Stop Bit
TXIF bit
(Interrupt Reg. Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
SENDB sampled here
Auto-Cleared
SENDB
(Transmit Shift
Reg. Empty Flag)
DS39616C-page 238
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Once the TXREG register transfers the data to the TSR
19.4 EUSART Synchronous Master
register (occurs in one TCYCLE), the TXREG is empty
and interrupt bit TXIF (PIR1<4>) is set. The interrupt
can be enabled/disabled by setting/clearing enable bit,
TXIE (PIE1<4>). Flag bit, TXIF, will be set, regardless
of the state of enable bit, TXIE, and cannot be cleared
in software. It will reset only when new data is loaded
into the TXREG register.
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 RC6/TX/
CK/SS and RC7/RX/DT/SDO I/O pins to CK (clock)
and DT (data) lines, respectively.
While flag bit, TXIF, indicates the status of the TXREG
register, another bit, TRMT (TXSTA<1>), shows the sta-
tus 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 must poll this bit in order to determine
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 (BAUDCTL<4>). Setting
SCKP sets the Idle state on CK as high, while clearing
the bit, sets the Idle state 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 BRGH
and BRG16 bits, as required, to achieve the
desired baud rate.
19.4.1
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 19-2. 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 19-10:
SYNCHRONOUS TRANSMISSION
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
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
RC7/RX/DT/
SDO Pin
bit 0
bit 1
bit 2
bit 7
bit 0
bit 1
bit 7
Word 1
Word 2
RC6/TX/CK/
SS Pin
(SCKP = 0)
RC6/TX/CK/
SS 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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 239
PIC18F2331/2431/4331/4431
FIGURE 19-11:
SYNCHRONOUS TRANSMISSION (THROUGH TXEN)
RC7/RX/DT/SDO Pin
bit 0
bit 1
bit 2
bit 6
bit 7
RC6/TX/CK/SS Pin
Write to
TXREG Reg
TXIF bit
TRMT bit
TXEN bit
TABLE 19-7: REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER TRANSMISSION
Value on
all other
Resets
Value on
POR, BOR
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
RBIE
TMR0IF
INT0IF
RBIF
0000 000x
-000 0000
-000 0000
-111 1111
0000 000x
0000 0000
0000 0010
-1-1 0-00
0000 0000
0000 0000
0000 000u
-000 0000
-000 0000
-111 1111
0000 000x
0000 0000
0000 0010
-1-1 0-00
0000 0000
0000 0000
—
—
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
TXIF
TXIE
TXIP
SSPIF
CCP1IF TMR2IF TMR1IF
PIE1
SSPIE CCP1IE TMR2IE TMR1IE
SSPIP CCP1IP TMR2IP TMR1IP
IPR1
—
RCSTA
TXREG
TXSTA
BAUDCTL
SPEN
CREN ADDEN
FERR
OERR
RX9D
EUSART Transmit Register
CSRC
—
TX9
TXEN
—
SYNC SENDB
SCKP BRG16
BRGH
—
TRMT
WUE
TX9D
RCIDL
ABDEN
SPBRGH EUSART Baud Rate Generator Register High Byte
SPBRG
EUSART Baud Rate Generator Register Low Byte
Legend:
x= unknown, -= unimplemented, read as ‘0’. Shaded cells are not used for synchronous master transmission.
DS39616C-page 240
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
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.
19.4.2
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 RC7/
RX/DT/SDO 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 BRGH
and BRG16 bits, 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 19-12:
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 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
RC7/RX/DT/SDO
Pin
bit 0
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 7
RC6/TX/CK/SS
Pin
(SCKP = 0)
RC6/TX/CK/SS
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 19-8: REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER RECEPTION
Value on
all other
Resets
Value on
POR, BOR
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
RBIE
SSPIF
SSPIE
SSPIP
TMR0IF INT0IF
RBIF
0000 000x 0000 000u
—
—
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
TXIF
TXIE
TXIP
CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
CCP1IP TMR2IP TMR1IP -111 1111 -111 1111
PIE1
IPR1
—
RCSTA
RCREG
TXSTA
BAUDCTL
SPEN
CREN ADDEN
FERR
OERR
RX9D
0000 000x 0000 000x
0000 0000 0000 0000
0000 0010 0000 0010
-1-1 0-00 -1-1 0-00
0000 0000 0000 0000
0000 0000 0000 0000
EUSART Receive Register
CSRC
—
TX9
TXEN
—
SYNC
SCKP
SENDB
BRG16
BRGH
—
TRMT
WUE
TX9D
RCIDL
ABDEN
SPBRGH EUSART Baud Rate Generator Register High Byte
SPBRG
EUSART Baud Rate Generator Register Low Byte
Legend:
x= unknown, -= unimplemented, read as ‘0’. Shaded cells are not used for synchronous master reception.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 241
PIC18F2331/2431/4331/4431
To set up a Synchronous Slave Transmission:
19.5 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
supplied externally at the RC6/TX/CK/SS 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.
6. If 9-bit transmission is selected, the ninth bit
should be loaded in bit, TX9D.
19.5.1
EUSART SYNCHRONOUS SLAVE
TRANSMIT
7. Start transmission by loading data to the TXREG
register.
The operation of the Synchronous Master and Slave
modes are identical, except in the case of Sleep mode.
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 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 19-9: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE TRANSMISSION
Value on
all other
Resets
Value on
POR, BOR
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
RBIE
TMR0IF INT0IF
RBIF
0000 000x 0000 000u
—
—
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
TXIF
TXIE
TXIP
SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
SSPIP CCP1IP TMR2IP TMR1IP -111 1111 -111 1111
PIE1
IPR1
—
RCSTA
TXREG
TXSTA
BAUDCTL
SPEN
CREN ADDEN
FERR
OERR
RX9D
0000 000x 0000 000x
0000 0000 0000 0000
0000 0010 0000 0010
EUSART Transmit Register
CSRC
—
TX9
TXEN
—
SYNC SENDB
SCKP BRG16
BRGH
—
TRMT
WUE
TX9D
RCIDL
ABDEN -1-1 0-00 -1-1 0-00
0000 0000 0000 0000
SPBRGH EUSART Baud Rate Generator Register High Byte
SPBRG
EUSART Baud Rate Generator Register Low Byte
0000 0000 0000 0000
Legend:
x= unknown, -= unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave transmission.
DS39616C-page 242
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
To set up a Synchronous Slave Reception:
19.5.2
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 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 com-
plete. 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 19-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION
Value on
all other
Resets
Value on
POR, BOR
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
RBIE
TMR0IF INT0IF
RBIF
0000 000x 0000 000u
—
—
ADIF
ADIE
ADIP
RX9
RCIF
RCIE
RCIP
SREN
TXIF
TXIE
TXIP
SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
SSPIP CCP1IP TMR2IP TMR1IP -111 1111 -111 1111
PIE1
IPR1
—
RCSTA
RCREG
TXSTA
BAUDCTL
SPEN
CREN ADDEN
FERR
OERR
RX9D
0000 000x 0000 000x
0000 0000 0000 0000
0000 0010 0000 0010
EUSART Receive Register
CSRC
—
TX9
TXEN
—
SYNC
SCKP
SENDB
BRG16
BRGH
—
TRMT
WUE
TX9D
RCIDL
ABDEN -1-1 0-00 -1-1 0-00
0000 0000 0000 0000
SPBRGH EUSART Baud Rate Generator Register High Byte
SPBRG EUSART Baud Rate Generator Register Low Byte
0000 0000 0000 0000
Legend: x= unknown, -= unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave reception.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 243
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 244
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
• Selectable data acquisition timing
• Selectable A/D event trigger
20.0 10-BIT HIGH-SPEED
ANALOG-TO-DIGITAL
• Operation in Sleep using internal oscillator
CONVERTER (A/D) MODULE
These features lend themselves to many applications
including motor control, sensor interfacing, data
acquisition and process control. In many cases, these
features will reduce the software overhead associated
with standard A/D modules.
The high-speed Analog-to-Digital (A/D) Converter
module allows conversion of an analog signal to a
corresponding 10-bit digital number.
The A/D module supports up to 5 input channels on
PIC18F2331/2431 devices, and up to 9 channels on
the PIC18F4331/4431 devices.
The module has 9 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)
• A/D Control Register 3 (ADCON3)
• A/D Channel Select Register (ADCHS)
• Analog I/O Select Register 0 (ANSEL0)
This high-speed 10-bit A/D module offers the following
features:
• Up to 200K samples per second
• Two sample and hold inputs for dual-channel
simultaneous sampling
• Selectable Simultaneous or Sequential Sampling
modes
• 4-word data buffer for A/D results
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 245
PIC18F2331/2431/4331/4431
REGISTER 20-1: ADCON0: A/D CONTROL REGISTER 0
U-0
—
U-0
—
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
ADON
ACONV
ACSCH
ACMOD1
ACMOD0
GO/DONE
bit 7
bit 0
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
bit 7-6
bit 5
Unimplemented: Read as ‘0’
ACONV: Auto-Conversion Continuous Loop or Single-Shot Mode Select bit
1= Continuous Loop mode enabled
0= Single-Shot mode enabled
bit 4
ACSCH: Auto-Conversion Single or Multi-Channel Mode bit
1= Multi-Channel mode enabled, Single Channel mode disabled
0= Single Channel mode enabled, Multi-Channel mode disabled
bit 3-2
ACMOD: Auto-Conversion Mode Sequence Select bits
If ACSCH = 1:
00= Sequential Mode 1 (SEQM1); two samples are taken in sequence:
1st sample: Group A(1)
2nd sample: Group B(1)
01= Sequential Mode 2 (SEQM2); four samples are taken in sequence:
1st sample: Group A(1)
2nd sample: Group B(1)
3rd sample: Group C(1)
4th sample: Group D(1)
10= Simultaneous Mode 1 (STNM1); two samples are taken simultaneously:
1st sample: Group A and Group B(1)
11= Simultaneous Mode 2 (STNM2); two samples are taken simultaneously:
1st sample: Group A and Group B(1)
2nd sample: Group C and Group D(1)
If ACSCH = 0, Auto-Conversion Single Channel Sequence Mode Enabled:
00= Single Channel Mode 1 (SCM1); Group A is taken and converted(1)
01= Single Channel Mode 2 (SCM2); Group B is taken and converted(1)
10= Single Channel Mode 3 (SCM3); Group C is taken and converted(1)
11= Single Channel Mode 4 (SCM4); Group D is taken and converted(1)
bit 1
GO/DONE: A/D Conversion Status bit
1= A/D conversion cycle in progress. Setting this bit starts the A/D conversion cycle. If Auto-
Conversion Single-Shot mode is enabled (ACONV = 0), this bit is automatically cleared by
hardware when the A/D conversion (single or multi-channel depending on ACMOD settings) has
completed. If Auto-Conversion Continuous Loop mode is enabled (ACONV = 1), this bit remains
set after the user/trigger has set it (continuous conversions). It may be cleared manually by the user
to stop the conversions.
0= A/D conversion or multiple conversions completed/not in progress
bit 0
ADON: A/D On bit
1= A/D Converter module is enabled (after brief power-up delay, starts continuous sampling)
0= A/D Converter module is disabled
Note 1: Groups A, B, C, D refer to the ADCHS register.
DS39616C-page 246
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 20-2: ADCON1: A/D CONTROL REGISTER 1
R/W-0
R/W-0
U-0
—
R/W-0
R-0
R-0
R-0
R-0
VCFG1
VCFG0
FIFOEN
BFEMT
BFOVL
ADPNT1
ADPNT0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
bit 7-6
VCFG<1:0>: A/D VREF+ and A/D VREF- Source Selection bits
00= VREF+ = AVDD, VREF- = AVSS (AN2 and AN3 are analog inputs or digital I/O)
01= VREF+ = External VREF+, VREF- = AVSS (AN2 is an analog input or digital I/O)
10= VREF+ = AVDD, VREF- = External VREF- (AN3 is an analog input or digital I/O)
11= VREF+ = External VREF-, VREF- = External VREF-
bit 5
bit 4
Unimplemented: Read as ‘0’
FIFOEN: FIFO Buffer Enable bit
1= FIFO is enabled
0= FIFO is disabled
bit 3
BFEMT: Buffer Empty bit
1= FIFO is empty
0= FIFO is not empty (at least one of four locations has unread A/D result data)
bit 2
BFOVFL: Buffer Overflow bit
1= A/D result has overwritten a buffer location that has unread data
0= A/D result has not overflowed
bit 1-0
ADPNT<1:0>: Buffer Read Pointer Location bits
Designates the location to be read next.
00= Buffer address 0
01= Buffer address 1
10= Buffer address 2
11= Buffer address 3
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 247
PIC18F2331/2431/4331/4431
REGISTER 20-3: ADCON2: A/D CONTROL REGISTER 2
R/W-0
ADFM
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
ACQT3
ACQT2
ACQT1
ACQT0
ADCS2
ADCS1
ADCS0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
bit 7
ADFM: A/D Result Format Select bit
1= Right justified
0= Left justified
bit 6-3
ACQT<3:0>: A/D Acquisition Time Select bits
0000= No delay (Conversion starts immediately when GO/DONE is set)(1)
0001= 2 TAD
0010= 4 TAD
0011= 6 TAD
0100= 8 TAD
0101= 10 TAD
0110= 12 TAD
0111= 16 TAD
1000= 20 TAD
1001= 24 TAD
1010= 28 TAD
1011= 32 TAD
1100= 36 TAD
1101= 40 TAD
1110= 48 TAD
1111= 64 TAD
bit 2-0
ADCS<2:0>: A/D Conversion Clock Select bits
000= FOSC/2
001= FOSC/8
010= FOSC/32
011= FRC/4(2)
100= FOSC/4
101= FOSC/16
110= FOSC/64
111= FRC (Internal A/D RC Oscillator)
Note 1: If the A/D clock source is selected as RC, a time of TCY is added before sampling/conversion starts.
2: Due to an increased frequency of the internal A/D RC oscillator, FRC/4 provides clock frequencies
compatible with previous A/D modules.
DS39616C-page 248
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 20-4: ADCON3: A/D CONTROL REGISTER 3
R/W-0
R/W-0
U-0
—
R/W-0
SSRC4(1)
R/W-0
SSRC3(1)
R/W-0
SSRC2(1)
R/W-0
SSRC1(1)
R/W-0
SSRC0(1)
ADRS1
ADRS0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
bit 7-6
ADRS<1:0>: A/D Result Buffer Depth Interrupt Select Control for Continuous Loop Mode bits
The ADRS bits are ignored in Single-Shot mode.
00= Interrupt is generated when each word is written to the buffer
01= Interrupt is generated when the 2nd and 4th words are written to the buffer
10= Interrupt is generated when the 4th word is written to the buffer
11= Unimplemented
bit 5
Unimplemented: Read as ‘0’
bit 4-0
SSRC<4:0>: A/D Trigger Source Select bits(1)
00000= All triggers disabled
xxxx1= External interrupt RC3/INT0 starts A/D sequence
xxx1x= Timer5 starts A/D sequence
xx1xx= Input Capture 1 (IC1) starts A/D sequence
x1xxx= CCP2 compare match starts A/D sequence
1xxxx= Power Control PWM module rising edge starts A/D sequence
Note 1: SSRC<4:0> bits can be set such that any of the triggers will start conversion (e.g., SSRC<4:0)> = 00101
will trigger the A/D conversion sequence when RC3/INT0 or Input Capture 1 event occurs).
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 249
PIC18F2331/2431/4331/4431
REGISTER 20-5: ADCHS: A/D CHANNEL SELECT 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
GDSEL1
GDSEL0
GBSEL1
GBSEL0
GCSEL1
GCSEL0
GASEL1
GASEL0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
bit 7-6
bit 5-4
bit 3-2
bit 1-0
GDSEL1:GDSEL0: Group D Select bits
S/H-2 positive input.
00= AN3
01= AN7(1)
1x= Reserved
GBSEL1:GBSEL0: Group B Select bits
S/H-2 positive input.
00= AN1
01= AN5(1)
1x= Reserved
GCSEL1:GCSEL0: Group C Select bits
S/H-1 positive input.
00= AN2
01= AN6(1)
1x= Reserved
GASEL1:GASEL0: Group A Select bits
S/H-1 positive input.
00= AN0
01= AN4
10= AN8(1)
11= Reserved
Note 1: AN5 through AN8 are available only in PIC18F4331/4431 devices.
DS39616C-page 250
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 20-6: ANSEL0: ANALOG SELECT REGISTER 0(1)
R/W-1
ANS7(2)
R/W-1
ANS6(2)
R/W-1
ANS5(2)
R/W-1
ANS4
R/W-1
ANS3
R/W-1
ANS2
R/W-1
ANS1
R/W-1
ANS0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
bit 7-0
ANS<7:0>: Analog Input Function Select bits
Correspond to pins AN<7:0>.
1= Analog input
0= Digital I/O
Note 1: Setting a pin to an analog input disables the digital input buffer. The corresponding TRIS bit should be set
for an input and cleared for an output (analog or digital). The ANSx bits directly correspond to the ANx pins
(e.g., ANS0 = AN0, ANS1 = AN1, etc.). Unused ANSx bits are to be read as ‘0’.
2: ANS7 through ANS5 are available only on PIC18F4331/4431 devices.
REGISTER 20-7: ANSEL1: ANALOG SELECT REGISTER 1(1)
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
R/W-1
ANS8(2)
bit 7
bit 0
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
bit 7-1
bit 0
Unimplemented: Read as ‘0’
ANS8: Analog Input Function Select bit
1= Analog input
0= Digital I/O
Note 1: Setting a pin to an analog input disables the digital input buffer. The corresponding TRIS bit should be set
for an input and cleared for an output (analog or digital). The ANSx bits directly correspond to the ANx pins
(e.g., ANS8 = AN8, ANS9 = AN9, etc.). Unused ANSx bits are to be read as ‘0’.
2: ANS8 is available only on PIC18F4331/4431 devices.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 251
PIC18F2331/2431/4331/4431
The A/D channels are grouped into four sets of 2 or 3
channels. For the PIC18F2331/2431 devices, AN0 and
AN4 are in Group A, AN1 is in Group B, AN2 is in Group
C and AN3 is in Group D. For the PIC18F4331/4431
devices, AN0, AN4 and AN8 are in Group A, AN1 and
AN5 are in Group B, AN2 and AN6 are in Group C and
AN3 and AN7 are in Group D. The selected channel in
each group is selected by configuring the A/D Channel
Select Register, ADCHS.
The A/D Converter has a unique feature of being able
to operate while the device is in Sleep mode. To
operate in Sleep, the A/D conversion clock must be
derived from the A/D’s internal RC oscillator.
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
individually be configured as an analog input or digital
I/O using the ANSEL0 and ANSEL1 registers. The
ADRESH and ADRESL registers contain the value in
the result buffer pointed to by ADPNT<1:0>
(ADCON1<1:0>). The result buffer is a 4-deep circular
buffer that has a Buffer Empty status bit, BFEMT
(ADCON1<3>), and a Buffer Overflow status bit,
BFOVFL (ADCON1<2>).
The analog voltage reference is software selectable to
either the device’s positive and negative analog supply
voltage (AVDD and AVSS), or the voltage level on the
RA3/AN3/VREF+/CAP2/QEA and RA2/AN2/VREF-/
CAP1/INDX, or some combination of supply and
external sources. Register ADCON1 controls the
voltage reference settings.
FIGURE 20-1:
A/D BLOCK DIAGRAM
VCFG<1:0>
AVDD
AVSS
VREF+
VREF-
VREFH
VREFL
ADC
AN0
AN4
AN8(1)
Analog
MUX
ADRESH, ADRESL
MUX
10
AN2/VREF-
ADPNT<1:0>
AN6(1)
00
01
10
11
1
2
3
4
S/H-1
+
ACMOD<1:0>,
GxSEL<1:0>
S/H
-
4x10-Bit FIFO
AVSS
ACONV
ACSCH
ACMODx
AN1
AN5(1)
Analog
MUX
AN3/VREF+
S/H-2
+
AN7(1)
S/H
-
ACMOD<1:0>,
GxSEL<1:0>
AVSS
Seq.
Cntrl.
Note 1: AN5 through AN8 are available only on PIC18F4331/4431 devices.
DS39616C-page 252
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Continuous Loop mode allows the defined sequence to
20.1 Configuring the A/D Converter
be executed in a continuous loop when ACONV = 1. In
this mode, either the user can trigger the start of
conversion by setting the GO/DONE bit, or one of the
A/D triggers can start the conversion. The interrupt flag,
ADIF, is set based on the configuration of the bits,
ADRS<1:0> (ADCON3<7:6>). In Simultaneous modes,
STNM1 and STNM2, acquisition time must be config-
ured to ensure proper conversion of the analog input
signals.
The A/D Converter has two types of conversions, two
modes of operation and eight different Sequencing
modes. These features are controlled by the ACONV
bit (ADCON0<5>), ACSCH bit (ADCON0<4>) and
ACMOD<1:0> bits (ADCON0<3:2>). In addition, the
A/D channels are divided into four groups as defined
in the ADCHS register. Table 20-1 shows the
sequence configurations as controlled by the ACSCH
and ACMOD<1:0> bits.
20.1.2
CONVERSION MODE
20.1.1
CONVERSION TYPE
The ACSCH bit (ADCON0<4>) controls how many
channels are used in the configured sequence. When
clear, the A/D is configured for single channel conver-
sion and will convert the group selected by the
ACMOD<1:0> bits and the channel selected by the
GxSEL<1:0> bits (ADCHS register). When ACSCH = 1,
the A/D is configured for multiple channel conversion
and the sequence is defined by ACMOD<1:0>.
Two types of conversions exist in the high-speed 10-bit
A/D Converter module that are selected using the
ACONV bit. Single-Shot mode allows a single conversion
or sequence to be enabled when ACONV = 0. At the end
of the sequence, the GO/DONE bit will be automatically
cleared and the interrupt flag, ADIF, will be set. When
using Single-Shot mode and configured for
Simultaneous mode, STNM2, acquisition time must be
used to ensure proper conversion of the analog input
signals.
TABLE 20-1: AUTO-CONVERSION SEQUENCE CONFIGURATIONS
Mode
ACSCH ACMOD<1:0>
Description
Multi-Channel Sequential Mode 1
(SEQM1)
1
1
1
1
00
01
10
11
Groups A and B are sampled and converted
sequentially.
Multi-Channel Sequential Mode 2
(SEQM2)
Groups A, B, C and D are sampled and converted
sequentially.
Multi-Channel Simultaneous Mode 1
(STNM1)
Groups A and B are sampled simultaneously and
converted sequentially.
Multi-Channel Simultaneous Mode 2
(STNM2)
Groups A and B are sampled simultaneously, then
converted sequentially. Then, Group C and D are
sampled simultaneously, then converted
sequentially.
Single Channel Mode 1 (SCM1)
Single Channel Mode 2 (SCM2)
Single Channel Mode 3 (SCM3)
Single Channel Mode 4 (SCM4)
0
0
0
0
00
01
10
11
Group A is sampled and converted.
Group B is sampled and converted.
Group C is sampled and converted.
Group D is sampled and converted.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 253
PIC18F2331/2431/4331/4431
20.1.3
CONVERSION SEQUENCING
20.1.5
A/D MODULE INITIALIZATION
STEPS
The ACMOD<1:0> bits control the sequencing of the
A/D conversions. When ACSCH = 0, the A/D is
configured to sample and convert a single channel.
The ACMOD bits select which group to perform the
conversions and the GxSEL<1:0> bits select which
channel in the group is to be converted. If Single-Shot
mode is enabled, the A/D interrupt flag will be set after
the channel is converted. If Continuous Loop mode is
enabled, the A/D interrupt flag will be set according to
the ADRS<1:0> bits.
The following steps should be followed to initialize the
A/D module:
1. Configure the A/D module:
a) Configure analog pins, voltage reference
and digital I/O.
b) Select A/D input channels.
c) Select A/D Auto-Conversion mode
(Single-Shot or Continuous Loop).
d) Select A/D conversion clock.
e) Select A/D conversion trigger.
2. Configure A/D interrupt (if required):
a) Set GIE bit.
When ACSCH = 1, multiple channel sequencing is
enabled and two submodes can be selected. The first
mode is Sequential mode with two settings. The first
setting is called SEQM1 and first samples and converts
the selected Group A channel and then samples and
converts the selected Group B channel. The second
mode is called SEQM2 and it samples and converts a
Group A channel, Group B channel, Group C channel
and finally, a Group D channel.
b) Set PEIE bit.
c) Set ADIE bit.
d) Clear ADIF bit.
e) Select A/D trigger setting.
f) Select A/D interrupt priority.
3. Turn On ADC:
The second multiple channel sequencing submode is
Simultaneous Sampling mode. In this mode, there are
also two settings. The first setting is called STNM1 and
uses the two sample and hold circuits on the A/D
module. The selected Group A and B channels are
simultaneously sampled and then the Group A channel
is converted followed by the conversion of the Group B
channel. The second setting is called STNM2 and
starts the same as STNM1, but follows it with a
simultaneous sample of Group C and D channels. The
A/D module will then convert the Group C channel
followed by the Group D channel.
a) Set ADON bit in ADCON0 register.
b) Wait the required power-up setup time,
about 5-10 μs.
4. Start sample/conversion sequence:
a) Sample for a minimum of 2 TAD and start
conversion by setting the GO/DONE bit.
The GO/DONE bit is set by the user in
software or by the module if initiated by a
trigger.
b) If TACQ is assigned a value (multiple of TAD),
then setting the GO/DONE bit starts a
sample period of the TACQ value, then starts
a conversion.
20.1.4
TRIGGERING A/D CONVERSIONS
The PIC18F2331/2431/4331/4431 devices are capable
of triggering conversions from many different sources.
The same method used by all other microcontrollers of
setting the GO/DONE bit still works. The other trigger
sources are:
5. Wait for A/D conversion/conversions to
complete using one of the following options:
a) Poll for the GO/DONE bit to be cleared if in
Single-Shot mode.
• RC3/INT0 Pin
b) Wait for the A/D Interrupt Flag (ADIF) to be
set.
• Timer5 Overflow
• Input Capture 1 (IC1)
• CCP2 Compare Match
• Power Control PWM Rising Edge
c) Poll for the BFEMT bit to be cleared to
signify that at least the first conversion has
completed.
These triggers are enabled using the SSRC<4:0> bits
(ADCON3<4:0>). Any combination of the five sources
can trigger a conversion by simply setting the corre-
sponding bit in ADCON3. When the trigger occurs, the
GO/DONE bit is automatically set by the hardware and
then cleared once the conversion completes.
6. Read A/D results, clear ADIF flag, reconfigure
trigger.
DS39616C-page 254
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
20.2 A/D Result Buffer
20.3 A/D Acquisition Requirements
The A/D module has a 4-level result buffer with an
address range of 0 to 3, enabled by setting the FIFOEN
bit in the ADCON1 register. This buffer is implemented
in a circular fashion, where the A/D result is stored in
one location and the address is incremented. If the
address is greater than 3, the pointer is wrapped back
around to 0. The result buffer has a Buffer Empty Flag,
BFEMT, indicating when any data is in the buffer. It also
has a Buffer Overflow Flag, BFOVFL, which indicates
when a new sample has overwritten a location that was
not previously read.
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 20-2. 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.
Associated with the buffer is a pointer to the address for
the next read operation. The ADPNT<1:0> bits
configure the address for the next read operation.
These bits are read-only.
Note:
When the conversion is started, the
holding capacitor is disconnected from the
input pin.
The Result Buffer also has a configurable interrupt
trigger level that is configured by the ADRS<1:0> bits.
The user has three selections: interrupt flag set on
every write to the buffer, interrupt on every second write
to the buffer, or interrupt on every fourth write to the
buffer. ADPNT<1:0> is reset to ‘00’ every time a
conversion sequence is started (either by setting the
GO/DONE bit or on a trigger).
To calculate the minimum acquisition time,
Equation 20-1 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.
Note:
When right justified, reading ADRESL
increments the ADPNT<1:0> bits. When
left justified, reading ADRESH increments
the ADPNT<1:0> bits.
Example 20-1 shows the calculation of the minimum
required acquisition time TACQ. In this case, the
converter module is fully powered up at the outset and
therefore, the amplifier settling time, TAMP, is negligible.
This calculation is based on the following application
system assumptions:
CHOLD
Rs
Conversion Error
VDD
Temperature
VHOLD
=
=
≤
=
=
=
9 pF
100Ω
1/2 LSb
5V → Rss = 6 kΩ
50°C (system max.)
0V @ time = 0
EQUATION 20-1: ACQUISITION TIME
TACQ
=
=
Amplifier Settling Time + Holding Capacitor Charging Time + Temperature Coefficient
TAMP + TC + TCOFF
EQUATION 20-2: MINIMUM A/D HOLDING CAPACITOR CHARGING TIME
VHOLD
or
TC
=
=
(VREF – (VREF/2048)) • (1 – e(-TC/CHOLD(RIC + RSS + RS))
)
-(CHOLD)(RIC + RSS + RS) ln(1/2048)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 255
PIC18F2331/2431/4331/4431
EXAMPLE 20-1:
CALCULATING THE MINIMUM REQUIRED ACQUISITION TIME
TACQ
TAMP
TCOFF
=
=
=
TAMP + TC + TCOFF
Negligible
(Temp – 25°C)(0.005 μs/°C)
(50°C – 25°C)(0.005 μs/°C) = .13 μs
Temperature coefficient is only required for temperatures > 25°C. Below 25°C, TCOFF = 0 μs.
TC
=
-(CHOLD) (RIC + RSS + RS) ln(1/2047) μs
-(9 pF) (1 kΩ + 6 kΩ + 100Ω) ln(0.0004883) μs = .49 μs
TACQ
=
0 + .49 μs + .13 μs = .62 μs
Note: If the converter module has been in Sleep mode, TAMP is 2.0 μs from the time the part exits Sleep mode.
FIGURE 20-2:
ANALOG INPUT MODEL
VDD
Sampling
Switch
VT = 0.6V
ANx
SS
RIC ≤ 1k
RSS
Rs
CPIN
VAIN
ILEAKAGE
±500 nA
CHOLD = 9 pF
VT = 0.6V
5 pF
VSS
Legend: CPIN
= Input Capacitance
= Threshold Voltage
6V
5V
VDD 4V
VT
ILEAKAGE = Leakage Current at the pin due to
various junctions
3V
RIC
= Interconnect Resistance
2V
SS
= Sampling Switch
CHOLD
RSS
= Sample/Hold Capacitance (from DAC)
= Sampling Switch Resistance
5
6
7
8 9 10 11
Sampling Switch (kΩ)
Note:
For VDD < 2.7V and temperatures below 0°C, VAIN should be restricted to range: VAIN < VDD/2.
DS39616C-page 256
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
If desired, the ACQT bits can be set to select a
programmable acquisition time for the A/D module.
When triggered, the A/D module continues to sample
the input for the selected acquisition time, then
20.4 A/D Voltage References
If external voltage references are used instead of the
internal AVDD and AVSS sources, the source
impedance of the VREF+ and VREF- voltage sources
must be considered. During acquisition, currents
supplied by these sources are insignificant. However,
during conversion, the A/D module sinks and sources
current through the reference sources.
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 triggering the A/D. If an acquisition time is
programmed, there is nothing to indicate if the
acquisition time has ended or if the conversion has
begun.
In order to maintain the A/D accuracy, the voltage
reference source impedances should be kept low to
reduce voltage changes. These voltage changes occur
as reference currents flow through the reference
source impedance.
20.6 Selecting the A/D Conversion
Clock
Note:
When using external references, the
source impedance of the external voltage
references must be less than 75Ω in order
to achieve the specified ADC resolution. A
higher reference source impedance will
increase the ADC offset and gain errors.
Resistive voltage dividers will not provide a
low enough source impedance. To ensure
the best possible ADC performance, exter-
nal VREF inputs should be buffered with an
op amp or other low-impedance circuit.
The A/D conversion time per bit is defined as TAD. The
A/D conversion requires 12 TAD per 10-bit conversion.
The source of the A/D conversion clock is software
selectable. There are eight possible options for TAD:
• 2 TOSC
• 4 TOSC
• 8 TOSC
• 16 TOSC
• 32 TOSC
• 64 TOSC
• Internal RC Oscillator
• Internal RC Oscillator/4
20.5 Selecting and Configuring
Automatic Acquisition Time
For correct A/D conversions, the A/D conversion clock
(TAD) must be as short as possible, but greater than the
minimum TAD (approximately 416 ns, see parameter
A11 for more information).
The ADCON2 register allows the user to select an acqui-
sition time that occurs each time an A/D conversion is
triggered.
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 the
start of conversion. This occurs when the
ACQT3:ACQT0 bits (ADCON2<6:3>) remain in their
Reset state (‘0000’).
Table 20-2 shows the resultant TAD times derived from
the device operating frequencies and the A/D clock
source selected.
TABLE 20-2: TAD vs. DEVICE OPERATING FREQUENCIES
AD Clock Source (TAD)
Maximum Device Frequency
Operation
ADCS2:ADCS0
PIC18FXX31
PIC18LFXX31(4)
2 TOSC
4 TOSC
8 TOSC
16 TOSC
32 TOSC
64 TOSC
RC/4(3)
RC(3)
000
100
001
101
010
110
011
111
4.8 MHz
9.6 MHz
666 kHz
1.33 MHz
2.66 MHz
5.33 MHz
10.65 MHz
21.33 MHz
1.00 MHz(2)
4.0 MHz(2)
19.2 MHz
38.4 MHz
40.0 MHz
40.0 MHz
1.00 MHz(1)
4.0 MHz(2)
Note 1: The RC source has a typical TAD time of 2-6 μs.
2: The RC source has a typical TAD time of 0.5-1.5 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 unless in Single-Shot mode.
4: Low-power devices only.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 257
PIC18F2331/2431/4331/4431
20.7 Operation in Power-Managed
Modes
20.8 Configuring Analog Port Pins
The ANSEL0, ANSEL1, TRISA 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 ACQT3:ACQT0 and
ADCS2:ADCS0 bits in ADCON2 should be updated in
accordance with the power-managed mode clock that
will be used. After the power-managed mode is entered
(either of the power-managed Run modes), an A/D
acquisition or conversion may be started. Once an
acquisition or conversion is started, the device should
continue to be clocked by the same power-managed
mode clock source until the conversion has been com-
pleted. If desired, the device may be placed into the
corresponding power-managed Idle mode during the
conversion.
The A/D operation is independent of the state of the
ANSEL0, ANSEL1 and TRIS bits.
Note 1: When reading the PORT register, all pins
configured as analog input channels will
read as cleared (a low level). Pins
configured as digital inputs will convert an
analog input. Analog levels on a digitally
configured input will be accurately
converted.
2: Analog levels on any pin defined as a
digital input may cause the digital input
buffer to consume current out of the
device’s specification limits.
If the power-managed mode clock frequency is less
than 1 MHz, the A/D RC clock source should be
selected.
Operation in Sleep mode requires the A/D RC clock to
be selected. If bits ACQT3:ACQT0 are set to ‘0000’
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
and SCS bits in the OSCCON register must have
already been cleared prior to starting the conversion.
Note:
The A/D can operate in Sleep mode only
when configured for Single-Shot mode. If
the part is in Sleep mode, and it is possible
for a source other than the A/D module to
wake the part, the user must poll
ADCON0<GO/DONE> to ensure it is clear
before reading the result.
DS39616C-page 258
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Clearing the GO/DONE bit during a conversion will
abort the current conversion. The resulting buffer loca-
tion will contain the partially completed A/D conversion
sample. This will not set the ADIF flag, therefore, the
user must read the buffer location before a conversion
sequence overwrites it.
20.9 A/D Conversions
Figure 20-3 shows the operation of the A/D Converter
after the GO/DONE bit has been set and the
ACQT2:ACQT0 bits are cleared. A conversion is
started after the following instruction to allow entry into
Sleep mode before the conversion begins. The internal
A/D RC oscillator must be selected to perform a
conversion in Sleep.
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.
Figure 20-4 shows the operation of the A/D Converter
after the GO/DONE bit has been set, the ACQT3:ACQT0
bits are set to ‘010’ and a 4 TAD acquisition time is
selected before the conversion starts.
Note: The GO/DONE bit should NOT be set in
the same instruction that turns on the A/D.
FIGURE 20-3:
GO/DONE bit is
A/D CONVERSION TAD CYCLES (ACQT<2:0> = 000, TACQ = 0)
TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 TAD9 TAD10 TAD11
b6
set and holding
cap is
b8
b4
b3
b2
b9
b5
b7
b0
b1
disconnected
from analog
input
Conversion Starts
GO/DONE bit cleared on the rising edge of Q1 after the first Q3
following TAD11 and result buffer is loaded.(1)
Note 1: Conversion time is a minimum of 11 TAD + 2 TCY and a maximum of 11 TAD + 6 TCY.
FIGURE 20-4:
A/D CONVERSION TAD CYCLES (ACQT<3:0> = 0010, TACQ = 4 TAD)
TACQT Cycles
TAD Cycles
1
2
3
4
TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 TAD9 TAD10 TAD11
b6
b9
Conversion Starts
(Holding capacitor is disconnected)
b8
b5
b4
b3
b2
b7
b0
b1
Automatic
Acquisition
Time
A/D Triggered
GO/DONE bit cleared on the rising edge of Q1 after the first Q3
following TAD11 and result buffer is loaded.(1)
Note 1: In Continuous modes, next conversion starts at the end of TAD12.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 259
PIC18F2331/2431/4331/4431
Format Select bit (ADFM) controls this justification.
Figure 20-5 shows the operation of the A/D result
justification. The extra bits are loaded with ‘0’s. When
an A/D result will not overwrite these locations (A/D
disable), these registers may be used as two general
purpose 8-bit registers.
20.9.1
A/D RESULT REGISTER
The ADRESH:ADRESL register pair is the location
where the 10-bit A/D result is loaded at the completion
of the A/D conversion. This register pair is 16 bits wide.
The A/D module gives the flexibility to left or right justify
the 10-bit result in the 16-bit result register. The A/D
FIGURE 20-5:
A/D RESULT JUSTIFICATION
10-Bit Result
ADFM = 0
ADFM = 1
0
7
7
2 1 0 7
0 7 6 5
0
0000 00
0000 00
ADRESH
ADRESL
ADRESH
ADRESL
10-Bit Result
10-Bit Result
Left Justified
Right Justified
EQUATION 20-3: CONVERSION TIME FOR MULTI-CHANNEL MODES
Sequential Mode:
T = (TACQ)A + (TCON)A + [(TACQ)B – 12 TAD] + (TCON)B + [(TACQ)C – 12 TAD] + (TCON)C + [(TACQ)D – 12 TAD] + (TCON)D
Simultaneous Mode:
T = TACQ + (TCON)A + (TCON)B + TACQ + (TCON)C + (TCON)D
DS39616C-page 260
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 20-3: SUMMARY OF A/D REGISTERS
Value on
all other
Resets
Value on
POR, BOR
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
TXIE
TXIP
EEIF
EEIE
EEIP
RBIE
SSPIF
SSPIE
SSPIP
—
TMR0IF
CCP1IF
CCP1IE
CCP1IP
LVDIF
INT0IF
TMR2IF
TMR2IE
TMR2IP
—
RBIF
0000 000x 0000 000u
PIR1
PIE1
IPR1
PIR2
PIE2
IPR2
—
—
ADIF
ADIE
ADIP
—
RCIF
RCIE
RCIP
—
TMR1IF -000 0000 -000 0000
TMR1IE -000 0000 -000 0000
TMR1IP -111 1111 -111 1111
CCP2IF 0--0 -0-0 0--0 -0-0
CCP2IE 0--0 -0-0 0--0 -0-0
CCP2IP 1--1 -1-1 1--1 -1-1
xxxx xxxx uuuu uuuu
—
OSCFIF
OSCFIE
OSCFIP
—
—
—
LVDIE
—
—
—
—
LVDIP
—
ADRESH A/D Result Register High Byte
ADRESL A/D Result Register Low Byte
xxxx xxxx uuuu uuuu
ADCON0
ADCON1
ADCON2
ADCON3
ADCHS
ANSEL0
ANSEL1
PORTA
—
—
ACONV
—
ACSCH ACMOD1 ACMOD0 GO/DONE ADON --00 0000 --00 0000
VCFG1
ADFM
VCFG0
ACQT3
ADRS0
FIFOEN
ACQT1
SSRC4
BFEMT BFOVFL ADPNT1 ADPNT0 00-0 0000 00-0 0000
ACQT2
—
ACQT0
SSRC3
ADCS2
SSRC2
ADCS1
SSRC1
ADCS0 0000 0000 0000 0000
SSRC0 00-0 0000 00-0 0000
ADRS1
GDSEL1
GDSEL0 GBSEL1 GBSEL0 GCSEL1 GCSEL0 GASEL1 GASEL0 0000 0000 0000 0000
(6)
(6)
(6)
ANS7
ANS6
ANS5
—
ANS4
—
ANS3
—
ANS2
—
ANS1
—
ANS0 1111 1111 1111 1111
(5)
—
—
ANS8
RA0
---- ---1 ---- ---1
xx0x 0000 uu0u 0000
1111 1111 1111 1111
---- xxxx ---- uuuu
(4)
(4)
RA7
RA6
RA5
RA4
RA3
RA2
RA1
(4)
(4)
TRISA
TRISA7
TRISA6
PORTA Data Direction Register
(2)
(1)
(3)
(3)
(3)
PORTE
—
—
—
—
—
—
—
—
—
—
—
—
RE3
—
RA2
RA1
RA0
(3)
TRISE
PORTE Data Direction Register ---- -111 ---- -111
LATE Data Output Register ---- -xxx ---- -uuu
(3)
LATE
—
Legend:
x= unknown, u= unchanged, -= unimplemented, read as ‘0’, q= value depends on condition.
Shaded cells are not used for A/D conversion.
Note 1: RE3 port bit is available only as an input pin when MCLRE bit in Configuration register is ‘0’.
2: This register is not implemented on PIC18F2331/2431 devices.
3: These bits are not implemented on PIC18F2331/2431 devices.
4: These pins may be configured as port pins depending on the oscillator mode selected.
5: ANS5 through ANS8 are available only on the PIC18F4331/4431 devices.
6: Not available on 28-pin devices.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 261
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 262
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
until the device voltage is no longer in valid operating
range, to shut down the system. Voltage point VB is the
minimum valid operating voltage specification. This
occurs at time TB. The difference, TB – TA, is the total
time for shutdown.
21.0 LOW-VOLTAGE DETECT
In many applications, the ability to determine if the
device voltage (VDD) is below a specified voltage level
is a desirable feature. A window of operation for the
application can be created, where the application
software can do “housekeeping tasks” before the
device voltage exits the valid operating range. This can
be done using the Low-Voltage Detect module (LVD).
The block diagram for the LVD module is shown in
Figure 21-2. A comparator uses an internally gener-
ated reference voltage as the set point. When the
selected tap output of the device voltage crosses the
set point (is lower than), the LVDIF bit is set.
This module is a software programmable circuitry,
where a device voltage trip point can be specified.
When the voltage of the device becomes lower than the
specified point, 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 that interrupt source.
Each node in the resistor divider represents a “trip
point” voltage. The “trip point” voltage is the minimum
supply voltage level at which the device can operate
before the LVD module asserts an interrupt. When the
supply voltage is equal to the trip point, the voltage
tapped off of the resistor array is equal to the 1.2V
internal reference voltage generated by the voltage
reference module. The comparator then generates an
interrupt signal setting the LVDIF bit. This voltage is
software programmable to any one of 16 values (see
Figure 21-2). The trip point is selected by programming
the LVDL3:LVDL0 bits (LVDCON<3:0>).
The Low-Voltage Detect circuitry is completely under
software control. This allows the circuitry to be turned
off by the software, which minimizes the current
consumption for the device.
Figure 21-1 shows a possible application voltage curve
(typically for batteries). Over time, the device voltage
decreases. When the device voltage equals voltage VA,
the LVD logic generates an interrupt. This occurs at
time TA. The application software then has the time,
FIGURE 21-1:
TYPICAL LOW-VOLTAGE DETECT APPLICATION
VA
VB
Legend:
VA = LVD trip point
VB = Minimum valid device
operating voltage
TB
TA
Time
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 263
PIC18F2331/2431/4331/4431
FIGURE 21-2:
LOW-VOLTAGE DETECT (LVD) BLOCK DIAGRAM
VDD
LVDIN
LVD Control
Register
LVDIF
Internally Generated
LVDEN
Reference Voltage
1.2V
The LVD module has an additional feature that allows
the user to supply the sense voltage to the module
from an external source. This mode is enabled when
bits LVDL3:LVDL0 are set to ‘1111’. In this state, the
comparator input is multiplexed from the external input
pin, LVDIN (Figure 21-3). This gives users flexibility,
because it allows them to configure the Low-Voltage
Detect interrupt to occur at any voltage in the valid
operating range.
FIGURE 21-3:
LOW-VOLTAGE DETECT (LVD) WITH EXTERNAL INPUT BLOCK DIAGRAM
VDD
VDD
LVD Control
Register
LVDIN
LVDEN
Externally Generated
Trip Point
LVD
VxEN
BOREN
EN
BGAP
DS39616C-page 264
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
21.1 Control Register
The Low-Voltage Detect Control register controls the
operation of the Low-Voltage Detect circuitry.
REGISTER 21-1: LVDCON: LOW-VOLTAGE DETECT CONTROL REGISTER
U-0
—
U-0
—
R-0
R/W-0
R/W-0
LVDL3(1)
R/W-1
LVDL2(1)
R/W-0
LVDL1(1)
R/W-1
LVDL0(1)
IRVST
LVDEN
bit 7
bit 0
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
bit 7-6
bit 5
Unimplemented: Read as ‘0’
IRVST: Internal Reference Voltage Stable Flag bit
1= Indicates that the Low-Voltage Detect logic will generate the interrupt flag at the specified voltage
range
0= Indicates that the Low-Voltage Detect logic will not generate the interrupt flag at the specified
voltage range and the LVD interrupt should not be enabled
bit 4
LVDEN: Low-Voltage Detect Power Enable bit
1= Enables LVD, powers up LVD circuit
0= Disables LVD, powers down LVD circuit
bit 3-0
LVDL3:LVDL0: Low-Voltage Detection Limit bits(1)
1111= External analog input is used (input comes from the LVDIN pin)
1110= Maximum setting
.
.
.
0010= Minimum setting
0001= Reserved
0000= Reserved
Note 1: LVDL3:LVDL0 modes which result in a trip point below the valid operating voltage of the device are not
tested.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 265
PIC18F2331/2431/4331/4431
The following steps are needed to set up the LVD
module:
21.2 Operation
Depending on the power source for the device voltage,
the voltage normally decreases relatively slowly. This
means that the LVD module does not need to be
constantly operating. To decrease the current
requirements, the LVD circuitry only needs to be
enabled for short periods, where the voltage is
checked. After doing the check, the LVD module may
be disabled.
1. Write the value to the LVDL3:LVDL0 bits
(LVDCON register), which selects the desired
LVD trip point.
2. Ensure that LVD interrupts are disabled (the
LVDIE bit is cleared or the GIE bit is cleared).
3. Enable the LVD module (set the LVDEN bit in
the LVDCON register).
4. Wait for the LVD module to stabilize (the IRVST
bit to become set).
Each time that the LVD module is enabled, the circuitry
requires some time to stabilize. After the circuitry has
stabilized, all status flags may be cleared. The module
will then indicate the proper state of the system.
5. Clear the LVD interrupt flag, which may have
falsely become set, until the LVD module has
stabilized (clear the LVDIF bit).
6. Enable the LVD interrupt (set the LVDIE and the
GIE bits).
Figure 21-4 shows typical waveforms that the LVD
module may be used to detect.
FIGURE 21-4:
LOW-VOLTAGE DETECT WAVEFORMS
CASE 1:
LVDIF may not be set
VDD
VLVD
LVDIF
Enable LVD
Internally Generated
Reference Stable
TIRVST
LVDIF cleared in software
CASE 2:
VDD
VLVD
LVDIF
Enable LVD
TIRVST
Internally Generated
Reference Stable
LVDIF cleared in software
LVDIF cleared in software,
LVDIF remains set since LVD condition still exists
DS39616C-page 266
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
21.2.1
REFERENCE VOLTAGE SET POINT
21.3 Operation During Sleep
The internal reference voltage of the LVD module may
be used by other internal circuitry (the programmable
Brown-out Reset). If these circuits are disabled (lower
current consumption), the reference voltage circuit
requires a time to become stable before a low-voltage
condition can be reliably detected. This time is invariant
of system clock speed. This start-up time is specified in
electrical specification parameter 36. The low-voltage
interrupt flag will not be enabled until a stable reference
voltage is reached. Refer to the waveform in Figure 21-4.
When enabled, the LVD circuitry continues to operate
during Sleep. If the device voltage crosses the trip
point, the LVDIF 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.
21.4 Effects of a Reset
A device Reset forces all registers to their Reset state.
This forces the LVD module to be turned off.
21.2.2
CURRENT CONSUMPTION
When the module is enabled, the LVD comparator and
voltage divider are enabled and will consume static
current. The voltage divider can be tapped from
multiple places in the resistor array. Total current
consumption, when enabled, is specified in electrical
specification parameter D022B.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 267
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 268
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
22.1 Configuration Bits
22.0 SPECIAL FEATURES OF THE
CPU
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.
PIC18F2331/2431/4331/4431 devices include several
features intended to maximize system reliability and min-
imize cost through elimination of external components.
These are:
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.
• Oscillator Selection
• Resets:
- Power-on Reset (POR)
- Power-up Timer (PWRT)
- Oscillator Start-up Timer (OST)
- Brown-out Reset (BOR)
• Interrupts
Programming the Configuration registers is done in a
manner similar to programming the Flash memory. The
EECON1 register WR bit 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”.
• Watchdog Timer (WDT)
• Fail-Safe Clock Monitor
• Two-Speed Start-up
• Code Protection
• ID Locations
• In-Circuit Serial Programming™ (ICSP™)
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, PIC18F2331/2431/4331/
4431 devices have a Watchdog Timer, which is either
permanently enabled via the Configuration bits, or
software controlled (if configured as disabled).
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
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.
All of these features are enabled and configured by
setting the appropriate Configuration register bits.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 269
PIC18F2331/2431/4331/4431
TABLE 22-1: 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
300000h CONFIG1L
—
—
—
—
—
—
—
—
—
—
---- ----
11-- 1111
---- 1111
--11 1111
--11 11--
1--1 11-1
1--- -1-1
---- ----
---- 1111
11-- ----
---- 1111
111- ----
---- 1111
-1-- ----
300001h CONFIG1H IESO FCMEN
FOSC3
BORV1
FOSC2
FOSC1
FOSC0
300002h CONFIG2L
300003h CONFIG2H
300004h CONFIG3L
—
—
—
—
—
—
—
BORV0 BOREN PWRTEN
WINEN
T1OSCMX
—
WDTPS3
HPOL
WDTPS2 WDTPS1 WDTPS0 WDTEN
—
LPOL
PWM4MX
—
PWMPIN
—
—
—
(1)
(1)
(1)
(1)
300005h CONFIG3H MCLRE
300006h CONFIG4L DEBUG
—
EXCLKMX
SSPMX
FLTAMX
—
—
—
—
LVP
—
—
STVREN
—
300007h CONFIG4H
300008h CONFIG5L
300009h CONFIG5H
30000Ah CONFIG6L
—
—
—
—
—
—
(1)
(1)
—
—
—
CP3
CP2
CP1
—
CP0
—
CPD
—
CPB
—
—
—
—
—
(1)
(1)
(1)
—
—
WRT3
—
WRT2
WRT1
—
WRT0
—
30000Bh CONFIG6H WRTD WRTB
WRTC
—
—
—
(1)
30000Ch CONFIG7L
30000Dh CONFIG7H
—
—
—
—
EBTR3
—
EBTR2
EBTR1
—
EBTR0
—
EBTRB
DEV1
—
—
—
(2)
(2)
3FFFFEh DEVID1
DEV2
DEV0
DEV8
REV4
DEV7
REV3
DEV6
REV2
DEV5
REV1
DEV4
REV0
DEV3
xxxx xxxx
(2)
3FFFFFh DEVID2
DEV10 DEV9
0000 0101
Legend: x= unknown, u= unchanged, -= unimplemented. Shaded cells are unimplemented, read as ‘0’.
Note 1: Unimplemented in PIC18F2331/2431 devices; maintain this bit set.
2: See Register 22-13 for DEVID1 values. DEVID registers are read-only and cannot be programmed by the user.
REGISTER 22-1: CONFIG1H: CONFIGURATION REGISTER 1 HIGH (BYTE ADDRESS 300001h)
R/P-1
IESO
R/P-1
U-0
—
U-0
—
R/P-1
R/P-1
R/P-1
R/P-1
FCMEN
FOSC3
FOSC2
FOSC1
FOSC0
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
U = Unchanged from programmed state
bit 7
bit 6
IESO: Internal External Switchover bit
1= Internal External Switchover mode enabled
0= Internal External 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
bit 3-0
Unimplemented: Read as ‘0’
FOSC<3:0>: Oscillator Selection bits
11xx= External RC oscillator, CLKO function on RA6
1001= Internal oscillator block, CLKO function on RA6 and port function on RA7
1000= Internal oscillator block, port function on RA6 and port function on 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
0010= HS oscillator
0001= XT oscillator
0000= LP oscillator
DS39616C-page 270
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 22-2: CONFIG2L: CONFIGURATION REGISTER 2 LOW (BYTE ADDRESS 300002h)
U-0
—
U-0
—
U-0
—
U-0
—
R/P-1
R/P-1
R/P-1
BOREN(1)
R/P-1
PWRTEN(1)
bit 0
BORV1
BORV0
bit 7
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
U = Unchanged from programmed state
bit 7-4
bit 3-2
Unimplemented: Read as ‘0’
BORV1:BORV0: Brown-out Reset Voltage bits
11= Reserved
10= VBOR set to 2.7V
01= VBOR set to 4.2V
00= VBOR set to 4.5V
bit 1
bit 0
BOREN: Brown-out Reset Enable bit(1)
1= Brown-out Reset enabled
0= Brown-out Reset disabled
PWRTEN: Power-up Timer Enable bit(1)
1= PWRT disabled
0= PWRT enabled
Note 1: Having BOREN = 1does not automatically override the PWRTEN to ‘0’ nor automatically enable the
Power-up Timer.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 271
PIC18F2331/2431/4331/4431
REGISTER 22-3:
CONFIG2H: CONFIGURATION REGISTER 2 HIGH (BYTE ADDRESS 300003h)
U-0
—
U-0
—
R/P-1
R/P-1
R/P-1
R/P-1
R/P-1
R/P-1
WINEN
WDTPS3
WDTPS2
WDTPS1
WDTPS0
WDTEN
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
U = Unchanged from programmed state
bit 7-6
bit 5
Unimplemented: Read as ‘0’
WINEN: Watchdog Timer Window Enable bit
1= WDT window disabled
0= WDT window enabled
bit 4-1
WDTPS<3:0>: 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)
DS39616C-page 272
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 22-4: CONFIG3L: CONFIGURATION REGISTER 3 LOW (BYTE ADDRESS 300004h)
U-0
—
U
R/P-1
R/P-1
HPOL(1)
R/P-1
LPOL(1)
R/P-1
PWMPIN(3)
U
U
—
T1OSCMX
—
—
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
U = Unchanged from programmed state
-n = Value when device is unprogrammed
bit 7-6
bit 5
Unimplemented: Read as ‘0’
T1OSCMX: Timer1 Oscillator Mode bit
1= Low-power Timer1 operation when microcontroller is in Sleep mode
0= Standard (legacy) Timer1 oscillator operation
bit 4
HPOL: High Side Transistors Polarity bit (i.e., Odd PWM Output Polarity Control bit)(1)
1= PWM1, 3, 5 and 7 are active-high (default)(2)
0= PWM1, 3, 5 and 7 are active-low(2)
bit 3
LPOL: Low Side Transistors Polarity bit (i.e., Even PWM Output Polarity Control bit)(1)
1= PWM0, 2, 4 and 6 are active-high (default)(2)
0= PWM0, 2, 4 and 6 are active-low(2)
bit 2
PWMPIN: PWM Output Pins Reset State Control bit(3)
1= PWM outputs disabled upon Reset (default)
0= PWM outputs drive active states upon Reset
bit 1-0
Unimplemented: Read as ‘0’
Note 1: Polarity control bits, HPOL and LPOL, define PWM signal output active and inactive states; PWM states
generated by the Fault inputs or PWM manual override.
2: PWM6 and PWM7 output channels are only available on PIC18F4331/4431 devices.
3: When PWMPIN = 0, PWMEN<2:0> = 101if device has eight PWM output pins (40 and 44-pin devices)
and PWMEN<2:0> = 100if the device has six PWM output pins (28-pin devices). PWM output polarity is
defined by HPOL and LPOL.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 273
PIC18F2331/2431/4331/4431
REGISTER 22-5: CONFIG3H: CONFIGURATION REGISTER 3 HIGH (BYTE ADDRESS 300005h)
R/P-1
U
U
R/P-1
R/P-1
R/P-1
U
R/P-1
MCLRE
—
—
EXCLKMX(1) PWM4MX(1)
SSPMX(1)
—
FLTAMX(1)
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
U = Unchanged from programmed state
bit 7
MCLRE: MCLR Pin Enable bit
1= MCLR pin enabled: RE3 input pin disabled
0= RE3 input pin enabled; MCLR disabled
bit 6-5
bit 4
Unimplemented: Read as ‘0’
EXCLKMX: TMR0/T5CKI External Clock MUX bit(1)
1= TMR0/T5CKI external clock input is multiplexed with RC3
0= TMR0/T5CKI external clock input is multiplexed with RD0
bit 3
bit 2
PWM4MX: PWM4 MUX bit(1)
1= PWM4 output is multiplexed with RB5
0= PWM4 output is multiplexed with RD5
SSPMX: SSP I/O MUX bit(1)
1= SCK/SCL clocks and SDA/SDI data are multiplexed with RC5 and RC4, respectively. SDO output
is multiplexed with RC7.
0= SCK/SCL clocks and SDA/SDI data are multiplexed with RD3 and RD2, respectively. SDO output
is multiplexed with RD1.
bit 1
bit 0
Unimplemented: Read as ‘0’
FLTAMX: FLTA MUX bit(1)
1= FLTA input is multiplexed with RC1
0= FLTA input is multiplexed with RD4
Note 1: Unimplemented in PIC18F2331/2431 devices; maintain this bit set.
DS39616C-page 274
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 22-6: CONFIG4L: CONFIGURATION REGISTER 4 LOW (BYTE ADDRESS 300006h)
R/P-1
U-0
—
U-0
—
U-0
—
U-0
—
R/P-1
LVP
U-0
—
R/P-1
DEBUG
STVREN
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
U = Unchanged from programmed state
bit 7
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
bit 6-3
bit 2
Unimplemented: Read as ‘0’
LVP: Low-Voltage ICSP™ Enable bit
1= Low-voltage ICSP enabled
0= Low-voltage 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
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 275
PIC18F2331/2431/4331/4431
REGISTER 22-7: CONFIG5L: CONFIGURATION REGISTER 5 LOW (BYTE ADDRESS 300008h)
U-0
—
U-0
—
U-0
—
U-0
—
R/C-1
CP3(1)
R/C-1
CP2(1)
R/C-1
CP1
R/C-1
CP0
bit 7
bit 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
bit 7-4
bit 3
Unimplemented: Read as ‘0’
CP3: Code Protection bit(1)
1= Block 3 (001800-001FFFh) not code-protected
0= Block 3 (001800-001FFFh) code-protected
bit 2
bit 1
bit 0
CP2: Code Protection bit(1)
1= Block 2 (001000-0017FFh) not code-protected
0= Block 2 (001000-0017FFh) code-protected
CP1: Code Protection bit
1= Block 1 (000800-000FFFh) not code-protected
0= Block 1 (000800-000FFFh) code-protected
CP0: Code Protection bit
1= Block 0 (000200-0007FFh) not code-protected
0= Block 0 (000200-0007FFh) code-protected
Note 1: Unimplemented in PIC18F2331/2431 devices; maintain this bit set.
REGISTER 22-8: CONFIG5H: CONFIGURATION REGISTER 5 HIGH (BYTE ADDRESS 300009h)
R/C-1
CPD
R/C-1
CPB
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
bit 7
bit 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
bit 7
CPD: Data EEPROM Code Protection bit
1= Data EEPROM not code-protected
0= Data EEPROM code-protected
bit 6
CPB: Boot Block Code Protection bit
1= Boot Block (000000-0001FFh) not code-protected
0= Boot Block (000000-0001FFh) code-protected
bit 5-0
Unimplemented: Read as ‘0’
DS39616C-page 276
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 22-9: CONFIG6L: CONFIGURATION REGISTER 6 LOW (BYTE ADDRESS 30000Ah)
U-0
—
U-0
—
U-0
—
U-0
—
R/P-1
WRT3(1)
R/P-1
WRT2(1)
R/P-1
WRT1
R/P-1
WRT0
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
U = Unchanged from programmed state
bit 7-4
bit 3
Unimplemented: Read as ‘0’
WRT3: Write Protection bit(1)
1= Block 3 (001800-001FFFh) not write-protected
0= Block 3 (001800-001FFFh) write-protected
bit 2
bit 1
bit 0
WRT2: Write Protection bit(1)
1= Block 2 (001000-0017FFh) not write-protected
0= Block 2 (001000-0017FFh) write-protected
WRT1: Write Protection bit
1= Block 1 (000800-000FFFh) not write-protected
0= Block 1 (000800-000FFFh) write-protected
WRT0: Write Protection bit
1= Block 0 (000200-0007FFh) not write-protected
0= Block 0 (000200-0007FFh) write-protected
Note 1: Unimplemented in PIC18F2331/2431 devices; maintain this bit set.
REGISTER 22-10: CONFIG6H: CONFIGURATION REGISTER 6 HIGH (BYTE ADDRESS 30000Bh)
R/P-1
R/P-1
R-1
WRTC(1)
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
WRTD
WRTB
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
U = Unchanged from programmed state
bit 7
WRTD: Data EEPROM Write Protection bit
1= Data EEPROM not write-protected
0= Data EEPROM write-protected
bit 6
WRTB: Boot Block Write Protection bit
1= Boot Block (000000-0001FFh) not write-protected
0= Boot BLOCK (000000-0001FFh) write-protected
bit 5
WRTC: Configuration Register Write Protection bit(1)
1= Configuration registers (300000-3000FFh) not write-protected
0= Configuration registers (300000-3000FFh) write-protected
bit 4-0
Unimplemented: Read as ‘0’
Note 1: This bit is read-only in normal execution mode; it can be written only in Program mode.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 277
PIC18F2331/2431/4331/4431
REGISTER 22-11: CONFIG7L: CONFIGURATION REGISTER 7 LOW (BYTE ADDRESS 30000Ch)
U-0
—
U-0
—
U-0
—
U-0
—
R/P-1
EBTR3(1)
R/P-1
EBTR2(1)
R/P-1
R/P-1
EBTR1
EBTR0
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
U = Unchanged from programmed state
bit 7-4
bit 3
Unimplemented: Read as ‘0’
EBTR3: Table Read Protection bit(1)
1= Block 3 (001800-001FFFh) not protected from table reads executed in other blocks
0= Block 3 (001800-001FFFh) protected from table reads executed in other blocks
bit 2
bit 1
bit 0
EBTR2: Table Read Protection bit(1)
1= Block 2 (001000-0017FFh) not protected from table reads executed in other blocks
0= Block 2 (001000-0017FFh) protected from table reads executed in other blocks
EBTR1: Table Read Protection bit
1= Block 1 (000800-000FFFh) not protected from table reads executed in other blocks
0= Block 1 (000800-000FFFh) protected from table reads executed in other blocks
EBTR0: Table Read Protection bit
1= Block 0 (000200-0007FFh) not protected from table reads executed in other blocks
0= Block 0 (000200-0007FFh) protected from table reads executed in other blocks
Note 1: Unimplemented in PIC18F2331/2431 devices; maintain this bit set.
REGISTER 22-12: CONFIG7H: CONFIGURATION REGISTER 7 HIGH (BYTE ADDRESS 30000Dh)
U-0
—
R/P-1
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
EBTRB
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
U = Unchanged from programmed state
bit 7
bit 6
Unimplemented: Read as ‘0’
EBTRB: Boot Block Table Read Protection bit
1= Boot Block (000000-0001FFh) not protected from table reads executed in other blocks
0= Boot Block (000000-0001FFh) protected from table reads executed in other blocks
bit 5-0
Unimplemented: Read as ‘0’
DS39616C-page 278
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 22-13: DEVID1: DEVICE ID REGISTER 1 FOR PIC18F2331/2431/4331/4431 DEVICES
R
R
R
R
R
R
R
R
DEV2
DEV1
DEV0
REV4
REV3
REV2
REV1
REV0
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
U = Unchanged from programmed state
bit 7-5
DEV2:DEV0: Device ID bits
These bits are used with the DEV<10:3> bits in the Device ID Register 2 to identify the part number.
000= PIC18F4331
001= PIC18F4431
100= PIC18F2331
101= PIC18F2431
bit 4-0
REV4:REV0: Revision ID bits
These bits are used to indicate the device revision.
REGISTER 22-14: DEVID2: DEVICE ID REGISTER 2 FOR PIC18F2331/2431/4331/4431 DEVICES
R
R
R
R
R
R
R
R
DEV10
DEV9
DEV8
DEV7
DEV6
DEV5
DEV4
DEV3
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
U = Unchanged from programmed state
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 0101= PIC18F2331/2431/4331/4431 devices
Note 1: 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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 279
PIC18F2331/2431/4331/4431
22.2 Watchdog Timer (WDT)
Note 1: The CLRWDT and SLEEP instructions
clear the WDT and postscaler counts
when executed.
For PIC18F2331/2431/4331/4431 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
Configuration Register 2H (see Register 22-3).
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: execute a
SLEEP or CLRWDT instruction, the IRCF bits
(OSCCON<6:4>) are changed or a clock failure has
occurred (see Section 22.4.1 “FSCM and the
Watchdog Timer”).
3: When a CLRWDT instruction is executed,
the postscaler count will be cleared.
4: If WINEN = 0, then CLRWDTmust be exe-
cuted only when WDTW = 1; otherwise, a
device Reset will result.
22.2.1
CONTROL REGISTER
Register 22-15 shows the WDTCON register. This is a
readable and writable register. The SWDTEN bit allows
software to enable or disable the WDT, but only if the
Configuration bit has disabled the WDT. The WDTW bit
is a read-only bit that indicates when the WDT count is
in the fourth quadrant (i.e., when the 8-bit WDT value is
b’11000000’ or greater).
Adjustments to the internal oscillator clock period using
the OSCTUNE register also affect the period of the
WDT by the same factor. For example, if the INTRC
period is increased by 3%, then the WDT period is
increased by 3%.
FIGURE 22-1:
WDT BLOCK DIAGRAM
Enable WDT
SWDTEN
INTRC Control
WDT Counter
÷125
WDTEN
Wake-up
from Sleep
INTRC Source
Change on IRCF bits
CLRWDT
WDT
Reset
Reset
Programmable Postscaler
1:1 to 1:32,768
All Device Resets
WDT
4
WDTPS<3:0>
Sleep
DS39616C-page 280
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
REGISTER 22-15: WDTCON: WATCHDOG TIMER CONTROL REGISTER
R-0
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
R/W-0
SWDTEN(1)
bit 0
WDTW
bit 7
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
bit 7
WDTW: Watchdog Timer Window bit
1= WDT count is in fourth quadrant
0= WDT count is not in fourth quadrant
bit 6-1
bit 0
Unimplemented: Read as ‘0’
SWDTEN: Software Enable/Disable for Watchdog Timer bit(1)
1= WDT is turned on
0= WDT is turned off
Note 1: If WDTEN Configuration bit = 1, then WDT is always enabled, irrespective of this control bit. If WDTEN
Configuration bit = 0, then it is possible to turn WDT on/off with this control bit.
TABLE 22-2: SUMMARY OF WATCHDOG TIMER REGISTERS
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
CONFIG2H
RCON
—
—
—
—
WINEN
—
WDTPS3 WDTPS2 WDTPS2 WDTPS0
WDTEN
BOR
IPEN
WDTW
RI
—
TO
—
PD
—
POR
—
WDTCON
—
SWDTEN
Legend: Shaded cells are not used by the Watchdog Timer.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 281
PIC18F2331/2431/4331/4431
In all other power-managed modes, Two-Speed Start-
22.3 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 INTRC oscil-
lator as a clock source until the primary clock source is
available. It is enabled by setting the IESO bit in
Configuration Register 1H (CONFIG1H<7>).
22.3.1
SPECIAL CONSIDERATIONS FOR
USING TWO-SPEED START-UP
Two-Speed Start-up is available only if the primary
oscillator mode is LP, XT, HS or HSPLL (Crystal-Based
modes). Other sources do not require a OST start-up
delay; for these, Two-Speed Start-up is disabled.
While using the INTRC oscillator in Two-Speed Start-
up, the device still obeys the normal command
sequences for entering power-managed modes,
including serial SLEEP instructions (refer to
Section 3.1.3 “Multiple Sleep Commands”). In
practice, this means that user code can change the
SCS1:SCS0 bit settings and issue SLEEP commands
before the OST times out. This would allow an applica-
tion 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 system clocking by checking the
status of the OSTS bit (OSCCON<3>). If the bit is set,
the primary oscillator is providing the system clock.
Otherwise, the internal oscillator block is providing the
clock during wake-up from Reset or Sleep mode.
Because the OSCCON register is cleared on Reset
events, the INTOSC (or postscaler) clock source is not
initially available after a Reset event; the INTRC clock
is used directly at its base frequency. 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
IRCF2:IRCF0 prior to entering Sleep mode.
FIGURE 22-2:
TIMING TRANSITION FOR TWO-SPEED START-UP (INTOSC TO HSPLL)
Q3
Q4
Q1
Q2 Q3 Q4 Q1 Q2 Q3 Q4
Q1
Q2
INTOSC
Multiplexer
OSC1
(1)
TOST
(1)
TPLL
PLL Clock
Output
1
2
3
4
5
6
7
8
Clock Transition
CPU Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
OSTS bit Set
Note 1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
PC + 4
PC + 6
Wake from Interrupt Event
DS39616C-page 282
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
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 IRCF2:IRCF0 prior to entering Sleep mode.
22.4 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 system clock to the internal oscillator block. The
FSCM function is enabled by setting the Fail-Safe
Clock Monitor Enable bit, FCMEN (CONFIG1H<6>).
Adjustments to the internal oscillator block using the
OSCTUNE register also affect the period of the FSCM
by the same factor. This can usually be neglected, as
the clock frequency being monitored is generally much
higher than the sample clock frequency.
When FSCM is enabled, the INTRC oscillator runs at
all times to monitor clocks to peripherals and provide
an instant backup clock in the event of a clock failure.
Clock monitoring (shown in Figure 22-3) is
accomplished by creating a sample clock signal, which
is the INTRC output divided by 64. This allows ample
time between FSCM sample clocks for a peripheral
clock edge to occur. The peripheral system 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 system 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.
22.4.1
FSCM AND THE WATCHDOG TIMER
Both the FSCM and the WDT are clocked by the
INTRC oscillator. Since the WDT operates with a
separate divider and counter, disabling the WDT has
no effect on the operation of the INTRC oscillator when
the FSCM is enabled.
FIGURE 22-3:
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 Monitor
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
INTRC
Source
C
Q
÷ 64
(32 μs)
488 Hz
(2.048 ms)
Clock
Failure
Detected
22.4.2
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 oscillator mode, such as
the OST or PLL timer). The INTOSC multiplexer provides
the system clock until the primary clock source becomes
ready (similar to a Two-Speed Start-up). The clock system
source is then switched to the primary 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
sample clock. If a sample clock falling edge occurs
while the CM is still set, a clock failure has been
detected (Figure 22-4). This causes the following:
• the FSCM generates an oscillator fail interrupt by
setting bit OSCFIF (PIR2<7>);
• the system 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
during 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.
Since the postscaler frequency from the internal
oscillator block may not be sufficiently stable, it may be
desirable to select another clock configuration and
enter an alternate power-managed mode (see
Section 22.3.1 “Special Considerations for Using
Two-Speed Start-up” and Section 3.1.3 “Multiple
Sleep Commands” for more details). This can be
done to attempt a partial recovery or execute a
controlled shutdown.
Entering a power-managed mode by loading the
OSCCON register and executing a SLEEP instruction
will clear the fail-safe condition. When the fail-safe
condition is cleared, the clock monitor will resume
monitoring the peripheral clock.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 283
PIC18F2331/2431/4331/4431
FIGURE 22-4:
FSCM TIMING DIAGRAM
Sample Clock
Oscillator
Failure
System
Clock
Output
CM Output
(Q)
Failure
Detected
OSCFIF
CM Test
CM Test
CM Test
Note:
The system clock is normally at a much higher frequency than the sample clock. The relative frequencies in
this example have been chosen for clarity.
22.4.3
FSCM INTERRUPTS IN
POWER-MANAGED MODES
22.4.4
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
system clock is EC, RC or INTRC modes, monitoring
can begin immediately following these events.
As previously mentioned, entering a power-managed
mode clears the fail-safe condition. 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.
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
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
configured as the system 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.
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.
If the interrupt is disabled, the device will not exit the
power-managed mode on oscillator failure. Instead, the
device will continue to operate as before, but clocked
by the INTOSC multiplexer. While in Idle mode, subse-
quent interrupts will cause the CPU to begin executing
instructions while being clocked by the INTOSC
multiplexer. The device will not transition to a different
clock source until the fail-safe condition is cleared.
Note:
The same logic that prevents false
oscillator failure interrupts on POR or wake
from Sleep will also prevent the detection of
the oscillator’s failure to start at all following
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.
As noted in Section 22.3.1 “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 system clock to become stable. When the new
powered-managed mode is selected, the primary clock
is disabled.
DS39616C-page 284
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Each of the five blocks has three code protection bits
associated with them. They are:
22.5 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
PIC® devices.
• Write-Protect bit (WRTn)
• External Block Table Read bit (EBTRn)
Figure 22-5 shows the program memory organization
for 8 and 16-Kbyte devices, and the specific code
protection bit associated with each block. The actual
locations of the bits are summarized in Table 22-3.
The user program memory is divided into five blocks.
One of these is a Boot Block of 512 bytes. The
remainder of the memory is divided into four blocks on
binary boundaries.
FIGURE 22-5:
CODE-PROTECTED PROGRAM MEMORY FOR PIC18F2331/2431/4331/4431
MEMORY SIZE/DEVICE
Block Code Protection
Controlled By:
8 Kbytes
(PIC18F2331/4331)
Address
Range
16 Kbytes
(PIC18F2431/4431)
Address
Range
0000h
0FFFh
0000h
01FFh
Boot Block
Boot Block
Block 0
CPB, WRTB, EBTRB
CP0, WRT0, EBTR0
0200h
0200h
Block 0
Block 1
0FFFh
1000h
0FFFh
1000h
Block 1
Block 2
Block 3
CP1, WRT1, EBTR1
CP2, WRT2, EBTR2
CP3, WRT3, EBTR3
1FFFh
1FFFh
2000h
2FFFh
3000h
Unimplemented
Read ‘0’s
3FFFh
3FFFh
TABLE 22-3: 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
CONFIG5H
CONFIG6L
—
CPD
—
—
CPB
—
—
—
—
—
—
—
—
—
CP3(1)
CP2(1)
CP1
—
CP0
—
300009h
30000Ah
30000Bh
30000Ch
30000Dh
—
—
—
WRT3(1) WRT2(1)
WRT1
WRT0
—
CONFIG6H WRTD
WRTB
—
WRTC
—
—
—
—
CONFIG7L
CONFIG7H
—
—
EBTR3(1) EBTR2(1) EBTR1
EBTR0
—
EBTRB
—
—
—
—
Legend: Shaded cells are unimplemented.
Note 1: Unimplemented in PIC18F2331/2431 devices; maintain this bit set.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 285
PIC18F2331/2431/4331/4431
22.5.1
PROGRAM MEMORY
CODE PROTECTION
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
protection 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.
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.
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-
tion that executes from a location outside of that block is
not allowed to read, and will result in reading ‘0’s.
Figures 22-6 through 22-8 illustrate table write and table
read protection.
FIGURE 22-6:
TABLE WRITE (WRTn) DISALLOWED
Register Values
Program Memory
Configuration Bit Settings
000000h
WRTB, EBTRB = 11
0001FFh
000200h
TBLPTR = 0002FFh
PC = 0007FEh
WRT0, EBTR0 = 01
TBLWT *
TBLWT *
0007FFh
000800h
WRT1, EBTR1 = 11
WRT2, EBTR2 = 11
WRT3, EBTR3 = 11
000FFFh
001000h
PC = 0017FEh
0017FFh
001800h
001FFFh
Results: All table writes disabled to Blockn whenever WRTn = 0.
DS39616C-page 286
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 22-7:
EXTERNAL BLOCK TABLE READ (EBTRn) DISALLOWED
Register Values
Configuration Bit Settings
Program Memory
000000h
WRTB, EBTRB = 11
0001FFh
000200h
TBLPTR = 0002FFh
PC = 000FFEh
WRT0, EBTR0 = 10
0007FFh
000800h
TBLRD *
WRT1, EBTR1 = 11
WRT2, EBTR2 = 11
000FFFh
001000h
0017FFh
001800h
WRT3, EBTR3 = 11
001FFFh
Results: All table reads from external blocks to Blockn are disabled whenever EBTRn = 0.
TABLAT register returns a value of ‘0’.
FIGURE 22-8:
EXTERNAL BLOCK TABLE READ (EBTRn) ALLOWED
Register Values
Configuration Bit Settings
Program Memory
000000h
WRTB, EBTRB = 11
WRT0, EBTR0 = 10
0001FFh
000200h
TBLPTR = 0002FFh
PC = 0007FEh
TBLRD *
0007FFh
000800h
WRT1, EBTR1 = 11
WRT2, EBTR2 = 11
WRT3, EBTR3 = 11
000FFFh
001000h
0017FFh
001800h
001FFFh
Results: Table reads permitted within Blockn, even when EBTRBn = 0.
TABLAT register returns the value of the data at the location TBLPTR.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 287
PIC18F2331/2431/4331/4431
To use the In-Circuit Debugger function of the micro-
controller, the design must implement In-Circuit Serial
Programming connections to MCLR/VPP, 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.
22.5.2
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 external writes to data EEPROM. The
CPU can continue to read and write data EEPROM
regardless of the protection bit settings.
22.9 Low-Voltage ICSP Programming
The LVP bit in Configuration Register 4L
(CONFIG4L<2>) enables Low-Voltage ICSP Program-
ming (LVP). When LVP is enabled, the microcontroller
can be programmed without requiring high voltage
being applied to the MCLR/VPP pin, but the RB5/PGM
pin is then dedicated to controlling Program mode entry
and is not available as a general purpose I/O pin.
22.5.3
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.
LVP is enabled in erased devices.
While programming using LVP, VDD is applied to the
MCLR/VPP pin as in normal execution mode. To enter
Programming mode, VDD is applied to the PGM pin.
22.6 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 TBLRDand TBLWTinstructions,
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: When Low-Voltage Programming is
enabled, the RB5 pin can no longer be
used as a general purpose I/O pin.
22.7
In-Circuit Serial Programming
3: When LVP is enabled, externally pull the
PGM pin to VSS to allow normal program
execution.
PIC18F2331/2431/4331/4431 microcontrollers 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 manu-
facture 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.
If Low-Voltage ICSP Programming mode will not be
used, the LVP bit can be cleared and RB5/PGM
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 pin). Once LVP has been disabled, only the
standard high-voltage programming is available and
must be used to program the device.
22.8 In-Circuit 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.
When the DEBUG bit in Configuration register
CONFIG4L 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 22-4 shows which resources are required by
the background debugger.
TABLE 22-4: DEBUGGER RESOURCES
I/O pins:
RB6, RB7
Stack:
2 levels
Program Memory:
Data Memory:
512 bytes
10 bytes
DS39616C-page 288
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
The control instructions may use some of the following
operands:
23.0 INSTRUCTION SET SUMMARY
The PIC18 instruction set adds many enhancements to
the previous PIC® instruction sets, while maintaining an
easy migration from these PIC instruction sets.
• A program memory address (specified by ‘n’)
• The mode of the call or return instructions
(specified by ‘s’)
Most instructions are a single program memory word
(16 bits), but there are three instructions that require
two program memory locations.
• The mode of the table read and table write
instructions (specified by ‘m’)
• No operand required
(specified by ‘—’)
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.
All instructions are a single word, except for three double
word instructions. These three instructions were made
double word instructions so that all the required informa-
tion is available in these 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 23-2 lists
byte-oriented, bit-oriented, literal and control
operations. Table 23-1 shows the opcode field
descriptions.
The double word instructions execute in two instruction
cycles.
Most byte-oriented instructions have three operands:
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.
1. The file register (specified by ‘f’)
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.
Figure 23-1 shows the general formats that the
instructions can have.
The destination designator ‘d’ specifies where the result
of the operation is to be placed. If ‘d’ is ‘0’, the result is
placed in the WREG register. If ‘d’ is ‘1’, the result is
placed in the file register specified in the instruction.
All examples use the format ‘nnh’ to represent a hexa-
decimal number, where ‘h’ signifies a hexadecimal
digit.
The Instruction Set Summary, shown in Table 23-2,
lists the instructions recognized by the Microchip
Assembler (MPASMTM Assembler). Section 23.2
“Instruction Set” provides a description of each
instruction.
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’)
23.1 Read-Modify-Write Operations
Any instruction that specifies a file register as part of
the instruction performs a Read-Modify-Write (R-M-W)
operation. The register is read, the data is modified,
and the result is stored according to either the instruc-
tion or the destination designator ‘d’. A read operation
is performed on a register even if the instruction writes
to that register.
The bit field designator ‘b’ selects the number of the bit
affected by the operation, while the file register desig-
nator ‘f’ represents the number of the file in which the
bit is located.
The literal instructions may use some of the following
operands:
• A literal value to be loaded into a file register
(specified by ‘k’)
For example, a “BCF PORTB, 1” instruction will read
PORTB, clear bit 1 of the data, then write the result back
to PORTB. The read operation would have the unin-
tended result that any condition that sets the RBIF flag
would be cleared. The R-M-W operation may also copy
the level of an input pin to its corresponding output latch.
• The desired FSR register to load the literal value
into (specified by ‘f’)
• No operand required
(specified by ‘—’)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 289
PIC18F2331/2431/4331/4431
TABLE 23-1: 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
d
Bit address within an 8-bit file register (0 to 7).
Bank Select Register. Used to select the current RAM bank.
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 locations.
8-bit register file address (0x00 to 0xFF).
fs
12-bit register file address (0x000 to 0xFFF). This is the source address.
12-bit register file address (0x000 to 0xFFF). This is the destination address.
Literal field, constant data or label (may be either an 8-bit, 12-bit or a 20-bit value).
Label name.
fd
k
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.
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)
u
Unused or Unchanged.
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.
TBLPTR
TABLAT
TOS
21-bit Table Pointer (points to a Program Memory location).
8-bit Table Latch.
Top-of-Stack.
PC
Program Counter.
PCL
Program Counter Low Byte.
Program Counter High Byte.
Program Counter High Byte Latch.
Program Counter Upper Byte Latch.
Global Interrupt Enable bit.
Watchdog Timer.
PCH
PCLATH
PCLATU
GIE
WDT
TO
Time-out bit.
PD
Power-Down bit.
C, DC, Z, OV, N
ALU Status bits: Carry, Digit Carry, Zero, Overflow, Negative.
Optional.
[
]
)
(
Contents.
→
< >
∈
Assigned to.
Register bit field.
In the set of.
italics
User-defined term (font is Courier New).
DS39616C-page 290
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 23-1:
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
MOVFF MYREG1, MYREG2
OPCODE
f (Source FILE #)
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 0x7F
OPCODE
k (literal)
k = 8-bit immediate value
Control operations
CALL, GOTOand 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
S
OPCODE
12 11
n<7:0> (literal)
0
n<19:8> (literal)
S = Fast bit
11 10
15
15
0
0
BRA MYFUNC
BC MYFUNC
OPCODE
n<10:0> (literal)
8 7
OPCODE
n<7:0> (literal)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 291
PIC18F2331/2431/4331/4431
TABLE 23-2: PIC18FXXXX INSTRUCTION SET
16-Bit Instruction Word
MSb LSb
Mnemonic,
Operands
Status
Affected
Description
Cycles
Notes
BYTE-ORIENTED FILE REGISTER 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 01da ffff ffff C, DC, Z, OV, N 1, 2
0010 00da ffff ffff C, DC, Z, OV, N 1, 2
ANDWF
CLRF
COMF
f, d, a AND WREG with f
f, a Clear f
f, d, a Complement f
0001 01da ffff ffff Z, N
0110 101a ffff ffff Z
0001 11da ffff ffff Z, N
1,2
2
1, 2
4
CPFSEQ
CPFSGT
CPFSLT
DECF
DECFSZ
DCFSNZ
INCF
INCFSZ
INFSNZ
IORWF
MOVF
f, a
f, a
f, a
Compare f with WREG, Skip = 1 (2 or 3) 0110 001a ffff ffff None
Compare f with WREG, Skip > 1 (2 or 3) 0110 010a ffff ffff None
Compare f with WREG, Skip < 1 (2 or 3) 0110 000a ffff ffff None
4
1, 2
f, d, a Decrement f
f, d, a Decrement f, Skip if 0
f, d, a Decrement f, Skip if Not 0
f, d, a Increment f
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
1
0000 01da ffff ffff C, DC, Z, OV, N 1, 2, 3, 4
1 (2 or 3) 0010 11da ffff ffff None
1 (2 or 3) 0100 11da ffff ffff None
1
1 (2 or 3) 0011 11da ffff ffff None
1 (2 or 3) 0100 10da ffff ffff None
1
1
2
1, 2, 3, 4
1, 2
0010 10da ffff ffff C, DC, Z, OV, N 1, 2, 3, 4
4
1, 2
1, 2
1
0001 00da ffff ffff Z, N
0101 00da ffff ffff Z, N
1100 ffff ffff ffff None
1111 ffff ffff ffff
MOVFF
f , f
Move f (source) to 1st word
s
d
s
f (destination) 2nd word
d
MOVWF
MULWF
NEGF
RLCF
RLNCF
RRCF
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
0110 111a ffff ffff None
0000 001a ffff ffff None
0110 110a ffff ffff C, DC, Z, OV, N 1, 2
0011 01da ffff ffff C, Z, N
0100 01da ffff ffff Z, N
0011 00da ffff ffff C, Z, N
0100 00da ffff ffff Z, N
0110 100a ffff ffff None
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)
1, 2
RRNCF
SETF
f, a
Set f
SUBFWB f, d, a Subtract f from WREG with
Borrow
0101 01da ffff ffff C, DC, Z, OV, N 1, 2
SUBWF
f, d, a Subtract WREG from f
1
1
0101 11da ffff ffff C, DC, Z, OV, N
0101 10da ffff ffff C, DC, Z, OV, N 1, 2
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 None
4
1, 2
1 (2 or 3) 0110 011a ffff ffff None
1
0001 10da ffff ffff Z, N
BIT-ORIENTED FILE REGISTER 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, b, a Bit Toggle f
1
1
1001 bbba ffff ffff None
1000 bbba ffff ffff None
1, 2
1, 2
3, 4
3, 4
1, 2
1 (2 or 3) 1011 bbba ffff ffff None
1 (2 or 3) 1010 bbba ffff ffff None
1
0111 bbba ffff ffff None
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 the 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 2-word instructions. The second word of these instructions will be executed as a NOP
unless 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.
5: If the table write starts the write cycle to internal memory, the write will continue until terminated.
DS39616C-page 292
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 23-2: PIC18FXXXX INSTRUCTION SET (CONTINUED)
16-Bit Instruction Word
Mnemonic,
Operands
Status
Affected
Description
Cycles
Notes
MSb LSb
CONTROL OPERATIONS
BC
BN
n
n
n
n
n
n
n
n
Branch if Carry
1 (2)
1110 0010 nnnn nnnn None
1110 0110 nnnn nnnn None
1110 0011 nnnn nnnn None
1110 0111 nnnn nnnn None
1110 0101 nnnn nnnn None
1110 0001 nnnn nnnn None
1110 0100 nnnn nnnn None
1101 0nnn nnnn nnnn None
1110 0000 nnnn nnnn None
1110 110s kkkk kkkk None
1111 kkkk kkkk 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
1 (2)
1 (2)
1 (2)
1 (2)
2
1 (2)
1 (2)
1 (2)
2
BNC
BNN
BNOV
BNZ
BOV
BRA
BZ
n
n, s
CALL
Call Subroutine 1st word
2nd word
CLRWDT
DAW
GOTO
—
—
n
Clear Watchdog Timer
Decimal Adjust WREG
Go to Address 1st word
2nd word
1
1
2
0000 0000 0000 0100 TO, PD
0000 0000 0000 0111 C, DC
1110 1111 kkkk kkkk None
1111 kkkk kkkk kkkk
NOP
NOP
POP
PUSH
RCALL
RESET
RETFIE
—
—
—
—
n
No Operation
No Operation
Pop Top of Return Stack (TOS) 1
Push Top of Return Stack (TOS) 1
Relative Call
1
1
0000 0000 0000 0000 None
1111 xxxx xxxx xxxx None
0000 0000 0000 0110 None
0000 0000 0000 0101 None
1101 1nnn nnnn nnnn None
0000 0000 1111 1111 All
0000 0000 0001 000s GIE/GIEH,
PEIE/GIEL
4
2
1
2
Software Device Reset
Return from Interrupt Enable
s
RETLW
RETURN
SLEEP
k
s
—
Return with Literal in WREG
Return from Subroutine
Go into Standby mode
2
2
1
0000 1100 kkkk kkkk None
0000 0000 0001 001s None
0000 0000 0000 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 the 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 2-word instructions. The second word of these instructions will be executed as a NOP
unless 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.
5: If the table write starts the write cycle to internal memory, the write will continue until terminated.
© 2007 Microchip Technology Inc.
Preliminary
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PIC18F2331/2431/4331/4431
TABLE 23-2: 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
Load 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 FSRx
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
1
1
1
2
1
Exclusive OR Literal with WREG 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 (5)
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 the 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 2-word instructions. The second word of these instructions will be executed as a NOP
unless 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.
5: If the table write starts the write cycle to internal memory, the write will continue until terminated.
DS39616C-page 294
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
23.2 Instruction Set
ADDLW
ADD Literal to W
ADDWF
ADD W to f
Syntax:
[ label ] ADDLW
0 ≤ k ≤ 255
k
Syntax:
[ label ] ADDWF
f [,d [,a]]
Operands:
Operation:
Status Affected:
Encoding:
Description:
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). If ‘a’ is ‘0’, the Access Bank
will be selected. If ‘a’ is ‘1’, the BSR is
used.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Words:
Cycles:
1
1
Decode
Read
literal ‘k’
Process
Data
Write to
W
Q Cycle Activity:
Q1
Example:
ADDLW
0x15
Q2
Q3
Q4
Before Instruction
0x10
After Instruction
0x25
Decode
Read
register ‘f’
Process
Data
Write to
destination
W
=
W
=
Example:
ADDWF
REG, W
Before Instruction
W
REG
=
=
0x17
0xC2
After Instruction
W
REG
=
=
0xD9
0xC2
© 2007 Microchip Technology Inc.
Preliminary
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PIC18F2331/2431/4331/4431
ADDWFC
ADD W and Carry bit to f
ANDLW
AND Literal with W
Syntax:
[ label ] ADDWFC
f [,d [,a]]
Syntax:
[ label ] ANDLW
0 ≤ k ≤ 255
k
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operands:
Operation:
Status Affected:
Encoding:
Description:
(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 ANDed with the
8-bit literal ‘k’. The result is placed in W.
0010
00da
ffff
ffff
Description:
Add W, the Carry flag and data memory
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 will be selected. If ‘a’ is ‘1’,
the BSR will not be overridden.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read literal
‘k’
Process
Data
Write to
W
Words:
Cycles:
1
1
Example:
ANDLW
0x5F
Q Cycle Activity:
Q1
Q2
Q3
Q4
Before Instruction
W
=
0xA3
0x03
Decode
Read
register ‘f’
Process
Data
Write to
destination
After Instruction
W
=
Example:
ADDWFC
REG, W
Before Instruction
Carry bit =
1
REG
W
=
=
0x02
0x4D
After Instruction
Carry bit =
0
REG
W
=
=
0x02
0x50
DS39616C-page 296
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
ANDWF
AND W with f
BC
Branch if Carry
Syntax:
[ label ] ANDWF
f [,d [,a]]
Syntax:
[ label ] 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 ANDed 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 will be selected. If ‘a’ is ‘1’,
the BSR will not be overridden (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.
Words:
Cycles:
1
1
Words:
Cycles:
1
1(2)
Q Cycle Activity:
Q1
Q Cycle Activity:
If Jump:
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
Q1
Q2
Q3
Q4
destination
Decode
Read literal
‘n’
Process
Data
Write to
PC
Example:
ANDWF
REG, W
No
operation
No
operation
No
operation
No
operation
Before Instruction
W
REG
=
=
0x17
0xC2
If No Jump:
Q1
Q2
Q3
Q4
After Instruction
Decode
Read literal
‘n’
Process
Data
No
operation
W
REG
=
=
0x02
0xC2
Example:
HERE
BC JUMP
Before Instruction
PC
=
address (HERE)
After Instruction
If Carry
PC
=
=
=
=
1;
address (JUMP)
0;
address (HERE + 2)
If Carry
PC
© 2007 Microchip Technology Inc.
Preliminary
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PIC18F2331/2431/4331/4431
BCF
Bit Clear f
BN
Branch if Negative
Syntax:
[ label ] BCF f,b[,a]
Syntax:
[ label ] 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
Description:
Bit ‘b’ in register ‘f’ is cleared. If ‘a’ is ‘0’,
the Access Bank will be selected, over-
riding the BSR value. If ‘a’ = 1, then the
bank will be selected as per the BSR
value (default).
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.
Words:
Cycles:
1
1
Words:
Cycles:
1
Q Cycle Activity:
Q1
1(2)
Q2
Q3
Q4
Q Cycle Activity:
If Jump:
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to
PC
Example:
BCF
FLAG_REG, 7
Before Instruction
FLAG_REG = 0xC7
After Instruction
FLAG_REG = 0x47
No
operation
No
operation
No
operation
No
operation
If No Jump:
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
Example:
HERE
BN Jump
Before Instruction
PC
=
address (HERE)
After Instruction
If Negative
PC
=
=
=
=
1;
address (Jump)
0;
address (HERE + 2)
If Negative
PC
DS39616C-page 298
Preliminary
© 2007 Microchip Technology Inc.
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BNC
Branch if Not Carry
BNN
Branch if Not Negative
Syntax:
[ label ] BNC
-128 ≤ n ≤ 127
n
Syntax:
[ label ] BNN
-128 ≤ n ≤ 127
n
Operands:
Operation:
Operands:
Operation:
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
If Carry
PC
After Instruction
If Negative
PC
=
=
=
=
0;
=
=
=
=
0;
address (Jump)
1;
address (HERE + 2)
address (Jump)
1;
address (HERE + 2)
If Carry
PC
If Negative
PC
© 2007 Microchip Technology Inc.
Preliminary
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PIC18F2331/2431/4331/4431
BNOV
Branch if Not Overflow
BNZ
Branch if Not Zero
Syntax:
[ label ] BNOV
-128 ≤ n ≤ 127
n
Syntax:
[ label ] BNZ
-128 ≤ n ≤ 127
if Zero bit is ‘0’,
n
Operands:
Operation:
Operands:
Operation:
if Overflow bit is ‘0’,
(PC) + 2 + 2n → PC
(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
If Overflow
PC
After Instruction
=
=
=
=
0;
If Zero
PC
If Zero
PC
=
=
=
=
0;
address (Jump)
1;
address (HERE + 2)
address (Jump)
1;
address (HERE + 2)
If Overflow
PC
DS39616C-page 300
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
BRA
Unconditional Branch
BSF
Bit Set f
Syntax:
[ label ] BRA
n
Syntax:
[ label ] BSF f,b[,a]
Operands:
Operation:
Status Affected:
Encoding:
Description:
-1024 ≤ n ≤ 1023
(PC) + 2 + 2n → PC
None
Operands:
0 ≤ f ≤ 255
0 ≤ b ≤ 7
a ∈ [0,1]
Operation:
1 → f<b>
1101
0nnn
nnnn
nnnn
Status Affected:
Encoding:
None
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’,
Access Bank will be selected, over-
riding the BSR value. If ‘a’ = 1, then the
bank will be selected as per the BSR
value.
Words:
Cycles:
1
2
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q Cycle Activity:
Q1
Decode
Read literal
‘n’
Process
Data
Write to
PC
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
No
operation
No
operation
No
operation
No
operation
Example:
BSF
FLAG_REG, 7
Example:
HERE
BRA Jump
Before Instruction
FLAG_REG
Before Instruction
=
=
0x0A
0x8A
PC
=
=
address (HERE)
address (Jump)
After Instruction
FLAG_REG
After Instruction
PC
© 2007 Microchip Technology Inc.
Preliminary
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PIC18F2331/2431/4331/4431
BTFSC
Bit Test File, Skip if Clear
BTFSS
Bit Test File, Skip if Set
Syntax:
[ label ] BTFSC f,b[,a]
Syntax:
[ label ] 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.
Description:
If bit ‘b’ in register ‘f’ is ‘1’, 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. If ‘a’ is ‘0’, the Access Bank
will be selected, overriding the BSR
value. If ‘a’ = 1, then the bank will be
selected as per the BSR value (default).
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
will be selected, overriding the BSR
value. If ‘a’ = 1, then the bank will be
selected as per the BSR value (default).
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
Example:
HERE
FALSE
TRUE
BTFSS
:
:
FLAG, 1
Before Instruction
PC
Before Instruction
PC
=
address (HERE)
=
address (HERE)
After Instruction
If FLAG<1>
PC
After Instruction
If FLAG<1>
PC
=
=
=
=
0;
=
=
=
=
0;
address (TRUE)
1;
address (FALSE)
address (FALSE)
1;
address (TRUE)
If FLAG<1>
PC
If FLAG<1>
PC
DS39616C-page 302
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
BTG
Bit Toggle f
BOV
Branch if Overflow
Syntax:
[ label ] BTG f,b[,a]
Syntax:
[ label ] BOV
-128 ≤ n ≤ 127
n
Operands:
0 ≤ f ≤ 255
0 ≤ b < 7
a ∈ [0,1]
Operands:
Operation:
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 pro-
gram will branch.
Description:
Bit ‘b’ in data memory location ‘f’ is
inverted. If ‘a’ is ‘0’, the Access Bank will
be selected, overriding the BSR value. If
‘a’ = 1, then the bank will be selected as
per the BSR value (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.
Words:
Cycles:
1
1
Words:
Cycles:
1
Q Cycle Activity:
Q1
1(2)
Q2
Q3
Q4
Q Cycle Activity:
If Jump:
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Q1
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
Write to
PC
Example:
BTG
PORTC,
4
Before Instruction:
PORTC
After Instruction:
PORTC
No
operation
No
operation
No
operation
No
operation
=
0111 0101 [0x75]
0110 0101 [0x65]
If No Jump:
Q1
=
Q2
Q3
Q4
Decode
Read literal
‘n’
Process
Data
No
operation
Example:
HERE
BOV JUMP
Before Instruction
PC
=
address (HERE)
After Instruction
If Overflow
PC
=
=
=
=
1;
address (JUMP)
0;
address (HERE + 2)
If Overflow
PC
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 303
PIC18F2331/2431/4331/4431
BZ
Branch if Zero
CALL
Subroutine Call
Syntax:
[ label ] BZ
n
Syntax:
[ label ] 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 mem-
ory 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
Example:
HERE
CALL THERE,FAST
If Zero
PC
If Zero
PC
=
=
=
=
1;
address (Jump)
0;
address (HERE + 2)
Before Instruction
PC
After Instruction
=
address (HERE)
PC
=
address (THERE)
TOS
WS
BSRS
=
=
=
address (HERE + 4)
W
BSR
STATUSS=
STATUS
DS39616C-page 304
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
CLRF
Clear f
CLRWDT
Clear Watchdog Timer
Syntax:
[ label ] CLRF f [,a]
Syntax:
[ label ] CLRWDT
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operands:
Operation:
None
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 reg-
ister. If ‘a’ is ‘0’, the Access Bank will be
selected, overriding the BSR value. If
‘a’ = 1, then the bank will be selected as
per the BSR value (default).
Description:
CLRWDTinstruction resets the
Watchdog Timer. It also resets the
postscaler of the WDT. Status bits TO
and PD are set.
Words:
Cycles:
1
1
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Decode
No
operation
Process
Data
No
operation
Example:
CLRF
FLAG_REG
Example:
CLRWDT
Before Instruction
FLAG_REG
Before Instruction
=
=
0x5A
0x00
WDT Counter
=
?
After Instruction
FLAG_REG
After Instruction
WDT Counter
WDT Postscaler
TO
=
=
=
=
0x00
0
1
1
PD
© 2007 Microchip Technology Inc.
Preliminary
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PIC18F2331/2431/4331/4431
COMF
Complement f
CPFSEQ
Compare f with W, Skip if f = W
Syntax:
[ label ] COMF f [,d [,a]]
Syntax:
[ label ] CPFSEQ f [,a]
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operation:
(f) – (W),
Operation:
(f) → dest
skip if (f) = (W)
(unsigned comparison)
Status Affected:
Encoding:
N, Z
Status Affected:
Encoding:
None
0001
11da
ffff
ffff
0110
001a
ffff
ffff
Description:
The contents of register ‘f’ are comple-
mented. 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 will be selected, over-
riding the BSR value. If ‘a’ = 1, then the
bank will be selected as per the BSR
value (default).
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. If ‘a’ is ‘0’, the Access Bank
will be selected, overriding the BSR
value. If ‘a’ = 1, then the bank will be
selected as per the BSR value (default).
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.
Example:
COMF
REG, W
Q Cycle Activity:
Q1
Before Instruction
Q2
Q3
Q4
REG
=
0x13
Decode
Read
register ‘f’
Process
Data
No
operation
After Instruction
REG
W
=
=
0x13
0xEC
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
CPFSEQ REG
NEQUAL
EQUAL
:
:
Before Instruction
PC Address
W
REG
=
=
=
HERE
?
?
After Instruction
If REG
PC
If REG
PC
=
=
≠
=
W;
Address (EQUAL)
W;
Address (NEQUAL)
DS39616C-page 306
Preliminary
© 2007 Microchip Technology Inc.
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CPFSGT
Compare f with W, Skip if f > W
CPFSLT
Compare f with W, Skip if f < W
Syntax:
[ label ] CPFSGT f [,a]
Syntax:
[ label ] CPFSLT f [,a]
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operation:
(f) − (W),
Operation:
(f) – (W),
skip if (f) > (W)
skip if (f) < (W)
(unsigned comparison)
(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 two-
cycle instruction. If ‘a’ is ‘0’, the Access
Bank will be selected, overriding the
BSR value. If ‘a’ = 1, then the bank will
be selected as per the BSR value
(default).
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. If ‘a’ is ‘0’, the
Access Bank will be selected. If ‘a’ is ‘1’,
the BSR will not be overridden (default).
Words:
Cycles:
1
1(2)
Words:
Cycles:
1
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
Q2
Q3
Q4
Q Cycle Activity:
Q1
Decode
Read
register ‘f’
Process
Data
No
operation
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
No
operation
If skip:
Q1
Q2
Q3
Q4
If skip:
Q1
No
operation
No
operation
No
operation
No
operation
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
If skip and followed by 2-word instruction:
Q1
Q2
Q3
Q4
If skip and followed by 2-word instruction:
No
No
No
No
operation
Q1
Q2
Q3
Q4
operation
operation
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
No
No
No
No
operation
operation
operation
operation
Example:
HERE
NLESS
LESS
CPFSLT REG
:
:
Example:
HERE
CPFSGT REG
NGREATER
GREATER
:
:
Before Instruction
PC
W
=
=
Address (HERE)
?
Before Instruction
PC
W
=
=
Address (HERE)
?
After Instruction
If REG
PC
If REG
PC
<
=
≥
=
W;
After Instruction
Address (LESS)
W;
Address (NLESS)
If REG
PC
If REG
PC
>
=
≤
=
W;
Address (GREATER)
W;
Address (NGREATER)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 307
PIC18F2331/2431/4331/4431
DAW
Decimal Adjust W Register
DECF
Decrement f
Syntax:
[ label ] DAW
Syntax:
[ label ] DECF f [,d [,a]]
Operands:
Operation:
None
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> 9] or [C = 1] then,
(W<7:4>) + 6 → 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). If ‘a’ is ‘0’, the Access Bank
will be selected, overriding the BSR
value. If ‘a’ = 1, then the bank will be
selected as per the BSR value (default).
(W<7:4>) → W<7:4>
Status Affected:
Encoding:
C, DC
0000
0000
0000
0111
Description:
DAW adjusts the 8-bit value in W,
resulting from the earlier addition of two
variables (each in packed BCD format)
and produces a correct packed BCD
result. The carry bit may be set by DAW
regardless of its setting prior to the DAW
instruction.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
Words:
Cycles:
1
1
destination
Example:
DECF
CNT,
Q Cycle Activity:
Q1
Q2
Q3
Q4
Before Instruction
CNT
Z
=
=
0x01
0
Decode
Read
register W
Process
Data
Write
W
Example 1:
DAW
After Instruction
CNT
Z
=
=
0x00
1
Before Instruction
W
=
0xA5
C
DC
=
=
0
0
After Instruction
W
=
0x05
C
DC
=
=
1
0
Example 2:
Before Instruction
W
C
DC
=
=
=
0xCE
0
0
After Instruction
W
=
0x34
C
DC
=
=
1
0
DS39616C-page 308
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
DECFSZ
Decrement f, Skip if 0
DCFSNZ
Decrement f, Skip if Not 0
Syntax:
[ label ] DECFSZ f [,d [,a]]
Syntax:
[ label ] 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. If ‘a’ is ‘0’, the
Access Bank will be selected,
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
instruction. If ‘a’ is ‘0’, the Access Bank
will be selected, overriding the BSR
value. If ‘a’ = 1, then the bank will be
selected as per the BSR value
(default).
overriding the BSR value. If ‘a’ = 1,
then the bank will be selected as per
the BSR value (default).
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
LOOP
Example:
HERE
ZERO
NZERO
DCFSNZ TEMP
:
:
CONTINUE
Before Instruction
PC
After Instruction
=
Address (HERE)
Before Instruction
TEMP
=
?
CNT
If CNT
PC
If CNT
PC
=
CNT – 1
0;
Address (CONTINUE)
0;
After Instruction
TEMP
=
=
≠
=
=
=
=
≠
=
TEMP – 1,
0;
Address (ZERO)
0;
If TEMP
PC
If TEMP
PC
Address (HERE + 2)
Address (NZERO)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 309
PIC18F2331/2431/4331/4431
GOTO
Unconditional Branch
INCF
Increment f
Syntax:
[ label ] GOTO
0 ≤ k ≤ 1048575
k → PC<20:1>
None
k
Syntax:
[ label ] INCF f [,d [,a]]
Operands:
Operation:
Status Affected:
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
k kkk
kkkk
kkkk
7
0
8
k
kkk kkkk
0010
10da
ffff
ffff
19
Description:
GOTOallows an unconditional branch
Description:
The contents of register ‘f’ are
anywhere within entire 2-Mbyte memory
range. The 20-bit value ‘k’ is loaded into
PC<20:1>. GOTOis always a two-cycle
instruction.
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 will be selected,
overriding the BSR value. If ‘a’ = 1, then
the bank will be selected as per the
BSR value (default).
Words:
Cycles:
2
2
Q Cycle Activity:
Q1
Words:
Cycles:
1
1
Q2
Q3
Q4
Decode
Read literal
‘k’<7:0>,
No
operation
Read literal
‘k’<19:8>,
Write to PC
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
No
operation
No
operation
No
operation
No
operation
Example:
INCF
CNT,
Example:
GOTO THERE
Before Instruction
After Instruction
CNT
Z
=
0xFF
PC
=
Address (THERE)
=
=
=
0
?
?
C
DC
After Instruction
CNT
Z
C
=
0x00
=
=
=
1
1
1
DC
DS39616C-page 310
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
INCFSZ
Increment f, Skip if 0
INFSNZ
Increment f, Skip if Not 0
Syntax:
[ label ] INCFSZ f [,d [,a]]
Syntax:
[ label ] INFSNZ 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
0011
11da
ffff
ffff
0100
10da
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 ‘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 will be selected,
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
instruction. If ‘a’ is ‘0’, the Access Bank
will be selected, overriding the BSR
value. If ‘a’ = 1, then the bank will be
selected as per the BSR value (default).
overriding the BSR value. If ‘a’ = 1, then
the bank will be selected as per the
BSR value (default).
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
Example:
HERE
ZERO
NZERO
INFSNZ REG
Before Instruction
PC
After Instruction
Before Instruction
PC
After Instruction
=
Address (HERE)
=
Address (HERE)
CNT
If CNT
PC
If CNT
PC
=
CNT + 1
0;
Address (ZERO)
0;
Address (NZERO)
REG
If REG
PC
If REG
PC
=
REG + 1
0;
Address (NZERO)
0;
Address (ZERO)
=
=
≠
=
≠
=
=
=
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 311
PIC18F2331/2431/4331/4431
IORLW
Inclusive OR Literal with W
IORWF
Inclusive OR W with f
Syntax:
[ label ] IORLW
0 ≤ k ≤ 255
(W) .OR. k → W
N, Z
k
Syntax:
[ label ] IORWF f [,d [,a]]
Operands:
Operation:
Status Affected:
Encoding:
Description:
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
8-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). If ‘a’ is ‘0’, the Access Bank
will be selected, overriding the BSR
value. If ‘a’ = 1, then the bank will be
selected as per the BSR value (default).
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
Process
Data
Write to
W
literal ‘k’
Words:
Cycles:
1
1
Example:
IORLW
0x9A
0x35
Q Cycle Activity:
Q1
Before Instruction
Q2
Q3
Q4
W
=
Decode
Read
register ‘f’
Process
Data
Write to
destination
After Instruction
W
=
0xBF
Example:
IORWF RESULT, W
Before Instruction
RESULT =
0x13
0x91
W
=
After Instruction
RESULT =
0x13
0x93
W
=
DS39616C-page 312
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
LFSR
Load FSR
MOVF
Move f
Syntax:
[ label ] LFSR f,k
Syntax:
[ label ] 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 will be selected, overriding the
BSR value. If ‘a’ = 1, then the bank will
be selected as per the BSR value
(default).
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
Words:
Cycles:
1
1
Example:
LFSR 2, 0x3AB
Q Cycle Activity:
Q1
After Instruction
FSR2H
Q2
Q3
Q4
=
=
0x03
0xAB
Decode
Read
register ‘f’
Process
Data
Write
W
FSR2L
Example:
MOVF
REG, W
0x22
Before Instruction
REG
W
=
=
0xFF
After Instruction
REG
W
=
=
0x22
0x22
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 313
PIC18F2331/2431/4331/4431
MOVFF
Move f to f
MOVLB
Move Literal to Low Nibble in BSR
Syntax:
[ label ] MOVFF f ,f
Syntax:
[ label ] MOVLB
0 ≤ k ≤ 255
k → BSR
k
s
d
Operands:
0 ≤ f ≤ 4095
Operands:
Operation:
Status Affected:
Encoding:
Description:
s
0 ≤ f ≤ 4095
d
Operation:
(f ) → f
s
d
None
Status Affected:
None
0000
0001
0000
kkkk
Encoding:
1st word (source)
2nd word (destin.)
The 8-bit literal ‘k’ is loaded into the
Bank Select Register (BSR).
1100
1111
ffff
ffff
ffff
ffff
ffff
ffff
s
d
Words:
Cycles:
1
1
Description:
The contents of source register ‘f ’ are
s
moved to destination register ‘f ’.
d
Location of source ‘f ’ can be anywhere
in the 4096-byte data space (000h to
s
Q Cycle Activity:
Q1
Q2
Q3
Q4
FFFh) and location of destination ‘f ’
d
Decode
Read literal
‘k’
Process
Data
Write
literal ‘k’ to
BSR
can also be anywhere from 000h to
FFFh.
Either source or destination can be W
(a useful special situation).
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
=
=
0x02
0x05
After Instruction
BSR register
The MOVFFinstruction should not be
used to modify interrupt settings while
any interrupt is enabled (see the note
on page 93).
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
=
=
0x33
0x11
After Instruction
REG1
=
=
0x33
0x33
REG2
DS39616C-page 314
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
MOVLW
Move Literal to W
MOVWF
Move W to f
Syntax:
[ label ] MOVLW
0 ≤ k ≤ 255
k → W
k
Syntax:
[ label ] MOVWF f [,a]
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operation:
(W) → f
None
Status Affected:
Encoding:
None
0000
1110
kkkk
kkkk
0110
111a
ffff
ffff
The 8-bit literal ‘k’ is loaded into W.
Description:
Move data from W to register ‘f’.
1
1
Location ‘f’ can be anywhere in the
256-byte bank. If ‘a’ is ‘0’, the Access
Bank will be selected, overriding the
BSR value. If ‘a’ = 1, then the bank will
be selected as per the BSR value
(default).
Cycles:
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to
W
Words:
Cycles:
1
1
Example:
MOVLW
0x5A
Q Cycle Activity:
Q1
After Instruction
Q2
Q3
Q4
W
=
0x5A
Decode
Read
register ‘f’
Process
Data
Write
register ‘f’
Example:
MOVWF
REG
Before Instruction
W
REG
=
=
0x4F
0xFF
After Instruction
W
REG
=
=
0x4F
0x4F
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 315
PIC18F2331/2431/4331/4431
MULLW
Multiply Literal with W
MULWF
Multiply W with f
Syntax:
[ label ] MULLW
0 ≤ k ≤ 255
k
Syntax:
[ label ] MULWF f [,a]
Operands:
Operation:
Status Affected:
Encoding:
Description:
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 PRODH:PRODL register
pair. PRODH contains the high byte.
W is unchanged.
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.
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.
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 will be
selected, overriding the BSR value. If
‘a’= 1, then the bank will be selected
as per the BSR value (default).
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write
Words:
Cycles:
1
1
registers
PRODH:
PRODL
Q Cycle Activity:
Q1
Q2
Q3
Q4
Example:
MULLW
0xC4
0xE2
?
?
Decode
Read
register ‘f’
Process
Data
Write
Before Instruction
registers
PRODH:
PRODL
W
PRODH
PRODL
=
=
=
After Instruction
W
Example:
MULWF
REG
=
=
=
0xE2
0xAD
0x08
Before Instruction
PRODH
PRODL
W
REG
PRODH
PRODL
=
=
=
=
0xC4
0xB5
?
?
After Instruction
W
=
=
=
=
0xC4
0xB5
0x8A
0x94
REG
PRODH
PRODL
DS39616C-page 316
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
NEGF
Negate f
NOP
No Operation
Syntax:
[ label ] NEGF f [,a]
Syntax:
[ label ] NOP
None
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operands:
Operation:
Status Affected:
Encoding:
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 will be selected,
overriding the BSR value. If ‘a’ = 1, then
the bank will be selected as per the
BSR value.
Description:
Words:
No operation.
1
1
Cycles:
Q Cycle Activity:
Q1
Q2
Q3
No
operation
Q4
Decode
No
No
operation
Words:
Cycles:
1
1
operation
Example:
None.
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 [0x3A]
1100 0110 [0xC6]
=
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 317
PIC18F2331/2431/4331/4431
POP
Pop Top of Return Stack
PUSH
Push Top of Return Stack
Syntax:
[ label ] POP
None
Syntax:
[ label ] PUSH
None
Operands:
Operation:
Status Affected:
Encoding:
Description:
Operands:
Operation:
Status Affected:
Encoding:
Description:
(TOS) → bit bucket
None
(PC + 2) → TOS
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 to implement a
software stack by modifying TOS, and
then push 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
=
=
0x00345A
0x000124
=
=
0x0031A2
0x014332
After Instruction
After Instruction
PC
TOS
=
=
=
0x000126
0x000126
0x00345A
TOS
PC
=
=
0x014332
NEW
Stack (1 level down)
DS39616C-page 318
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
RCALL
Relative Call
RESET
Reset
Syntax:
[ label ] RCALL
-1024 ≤ n ≤ 1023
(PC) + 2 → TOS,
n
Syntax:
[ label ] RESET
Operands:
Operation:
Operands:
Operation:
None
Reset all registers and flags that are
affected by a MCLR Reset.
(PC) + 2 + 2n → PC
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 PC to
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)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 319
PIC18F2331/2431/4331/4431
RETFIE
Return from Interrupt
RETLW
Return Literal to W
Syntax:
[ label ] RETFIE [s]
s ∈ [0,1]
Syntax:
[ label ] RETLW
0 ≤ k ≤ 255
k
Operands:
Operation:
Operands:
Operation:
(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 8-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
No
No
Words:
Cycles:
1
2
operation
operation
operation
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
BSR
STATUS
=
=
=
=
=
TOS
WS
BSRS
STATUSS
1
RETLW kn
; End of table
Before Instruction
W
=
0x07
GIE/GIEH, PEIE/GIEL
After Instruction
W
=
value of kn
DS39616C-page 320
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
RETURN
Return from Subroutine
RLCF
Rotate Left f through Carry
Syntax:
[ label ] RETURN [s]
s ∈ [0,1]
Syntax:
[ label ]
RLCF f [,d [,a]]
Operands:
Operation:
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
will be selected, overriding the BSR
value. If ‘a’ = 1, then the bank will be
selected as per the BSR value (default).
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).
register f
C
Words:
Cycles:
1
2
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q2
Read
register ‘f’
Q3
Process
Data
Q4
Decode
No
operation
Process
Data
POP PC
from stack
Decode
Write to
destination
No
No
No
No
operation
operation
operation
operation
Example:
RLCF
REG, W
Before Instruction
REG
C
=
=
1110 0110
0
Example:
RETURN
After Interrupt
After Instruction
PC = TOS
REG
W
=
=
=
1110 0110
1100 1100
1
C
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 321
PIC18F2331/2431/4331/4431
RLNCF
Rotate Left f (No Carry)
RRCF
Rotate Right f through Carry
Syntax:
[ label ]
RLNCF f [,d [,a]]
Syntax:
[ label ] 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 will be selected,
overriding the BSR value. If ‘a’ is ‘1’,
then the bank will be selected as per
the BSR value (default).
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 will be selected, over-
riding the BSR value. If ‘a’ is ‘1’, then
the bank will be selected as per the
BSR value (default).
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
Before Instruction
REG
After Instruction
Example:
RRCF
REG, W
=
1010 1011
0101 0111
Before Instruction
REG
C
=
=
1110 0110
0
REG
=
After Instruction
REG
W
C
=
=
=
1110 0110
0111 0011
0
DS39616C-page 322
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
RRNCF
Rotate Right f (No Carry)
SETF
Set f
Syntax:
[ label ] RRNCF f [,d [,a]]
Syntax:
[ label ] 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. 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).
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).
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
Q Cycle Activity:
Q1
Before Instruction
Q2
Q3
Q4
REG
=
=
0x5A
0xFF
Decode
Read
register ‘f’
Process
Data
Write to
destination
After Instruction
REG
Example 1:
RRNCF
REG, 1, 0
Before Instruction
REG
After Instruction
REG
=
1101 0111
1110 1011
RRNCF REG, W
=
Example 2:
Before Instruction
W
REG
=
=
?
1101 0111
After Instruction
W
REG
=
=
1110 1011
1101 0111
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 323
PIC18F2331/2431/4331/4431
SLEEP
Enter Sleep Mode
SUBFWB
Subtract f from W with Borrow
Syntax:
[ label ] SLEEP
Syntax:
[ label ] SUBFWB f [,d [,a]]
Operands:
Operation:
None
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). 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).
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.
Words:
Cycles:
1
1
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q Cycle Activity:
Q1
Decode
No
operation
Process
Data
Go to
Sleep
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
SLEEP
Example 1:
SUBFWB REG
Before Instruction
TO
PD
=
=
?
?
Before Instruction
REG
W
C
=
=
=
0x03
0x02
0x01
After Instruction
TO
PD
=
=
1 †
0
After Instruction
REG
W
C
Z
N
=
0xFF
0x02
0x00
0x00
=
=
=
=
†
If WDT causes wake-up, this bit is cleared.
0x01 ; result is negative
Example 2:
Before Instruction
SUBFWB
REG, 0, 0
REG
W
C
=
=
=
2
5
1
After Instruction
REG
W
C
Z
N
=
2
3
1
0
0
=
=
=
=
; result is positive
Example 3:
Before Instruction
SUBFWB
REG, 1, 0
REG
W
C
=
=
=
1
2
0
After Instruction
REG
W
C
Z
N
=
0
2
1
1
0
=
=
=
=
; result is zero
DS39616C-page 324
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
SUBLW
Subtract W from Literal
SUBWF
Syntax:
Subtract W from f
Syntax:
[ label ] SUBLW
0 ≤ k ≤ 255
k
[ label ] SUBWF f [,d [,a]]
Operands:
Operation:
Status Affected:
Encoding:
Description:
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 8-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). 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).
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to
W
Example 1:
SUBLW 0x02
Words:
Cycles:
1
1
Before Instruction
W
C
=
=
1
?
Q Cycle Activity:
Q1
After Instruction
Q2
Q3
Q4
W
C
Z
=
1
Decode
Read
register ‘f’
Process
Data
Write to
destination
=
=
=
1
0
0
; result is positive
N
Example 1:
SUBWF REG
Example 2:
SUBLW 0x02
Before Instruction
REG
W
C
=
=
=
3
2
?
Before Instruction
W
C
=
=
2
?
After Instruction
After Instruction
REG
W
C
Z
N
=
1
2
W
C
Z
=
0
=
=
=
=
=
=
=
1
1
0
; result is zero
1
0
0
;result is positive
N
Example 3:
Before Instruction
SUBLW 0x02
Example 2:
SUBWF REG, W
Before Instruction
W
C
=
=
3
?
REG
W
C
=
=
=
2
2
?
After Instruction
W
C
Z
=
FF ; (2’s complement)
After Instruction
=
=
=
0
0
1
; result is negative
REG
W
C
Z
N
=
2
0
=
=
=
=
N
1
1
0
;result is zero
Example 3:
SUBWF REG
Before Instruction
REG
W
C
=
=
=
0x01
0x02
?
After Instruction
REG
W
C
Z
N
=
0xFFh ;(2’s complement)
0x02
0x00 ;result is negative
0x00
0x01
=
=
=
=
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 325
PIC18F2331/2431/4331/4431
SUBWFB
Syntax:
Subtract W from f with Borrow
SWAPF
Swap f
Syntax:
[ label ] SWAPF f [,d [,a]]
[ label ] SUBWFB 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<3:0>) → dest<7:4>,
(f<7:4>) → dest<3:0>
Operation:
(f) – (W) – (C) → dest
Status Affected:
Encoding:
N, OV, C, DC, Z
Status Affected:
Encoding:
None
0101
10da
ffff
ffff
0011
10da
ffff
ffff
Description:
Subtract W and the carry flag (borrow)
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). 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).
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 will be selected, over-
riding the BSR value. If ‘a’ is ‘1’, then
the bank will be selected as per the
BSR value (default).
Words:
Cycles:
1
1
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
Decode
Read
register ‘f’
Process
Data
Write to
destination
destination
Example 1:
SUBWFB REG, 1, 0
Before Instruction
Example:
SWAPF
REG
REG
W
C
=
=
=
0x19
0x0D
0x01
(0001 1001)
(0000 1101)
Before Instruction
REG
=
0x53
0x35
After Instruction
After Instruction
REG
=
REG
W
C
Z
N
=
0x0C
0x0D
0x01
0x00
0x00
(0000 1011)
(0000 1101)
=
=
=
=
; result is positive
Example 2:
SUBWFB REG, 0, 0
Before Instruction
REG
W
C
=
=
=
0x1B
0x1A
0x00
(0001 1011)
(0001 1010)
(0001 1011)
; result is zero
After Instruction
REG
W
C
Z
N
=
0x1B
0x00
0x01
0x01
0x00
=
=
=
=
Example 3:
Before Instruction
SUBWFB REG, 1, 0
REG
W
C
=
=
=
0x03
0x0E
0x01
(0000 0011)
(0000 1101)
After Instruction
REG
=
0xF5
(1111 0100)
; [2’s comp]
W
C
Z
=
=
=
=
0x0E
0x00
0x00
0x01
(0000 1101)
N
; result is negative
DS39616C-page 326
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TBLRD
Table Read
TBLRD
Table Read (cont’d)
Syntax:
[ label ]
TBLRD ( *; *+; *-; +*)
Example 1:
TBLRD *+ ;
Operands:
Operation:
None
Before Instruction
TABLAT
TBLPTR
MEMORY(0x00A356)
=
=
=
0x55
0x00A356
0x34
if TBLRD *,
(Prog Mem (TBLPTR)) → TABLAT,
TBLPTR – No Change;
if TBLRD *+,
After Instruction
(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
TABLAT
TBLPTR
=
=
0x34
0x00A357
Example 2:
TBLRD +* ;
Before Instruction
TABLAT
=
=
=
=
0xAA
0x01A357
0x12
TBLPTR
Status Affected: None
MEMORY(0x01A357)
MEMORY(0x01A358)
After Instruction
Encoding:
0000
0000
0000
10nn
nn = 0
0x34
*
TABLAT
TBLPTR
=
=
0x34
0x01A358
=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: Least Significant Byte 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
No
Q3
No
Q4
Decode
No
operation
operation
operation
No
No operation
No
No operation
(Write
TABLAT)
operation (Read Program operation
Memory)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 327
PIC18F2331/2431/4331/4431
TBLWT
Table Write
TBLWT Table Write (Continued)
Syntax:
[ label ] TBLWT ( *; *+; *-; +*)
Words:
Cycles:
1
2
Operands:
Operation:
None
if TBLWT*,
Q Cycle Activity:
Q1
(TABLAT) → Holding Register,
TBLPTR – No Change;
if TBLWT*+,
Q2
Q3
Q4
Decode
No
No
No
(TABLAT) → Holding Register,
(TBLPTR) + 1 → TBLPTR;
if TBLWT*-,
(TABLAT) → Holding Register,
(TBLPTR) – 1 → TBLPTR;
if TBLWT+*,
(TBLPTR) + 1 → TBLPTR,
(TABLAT) → Holding Register
operation
operation
operation
No
operation
No
No
No
operation
(Read
TABLAT)
operation
operation
(Write to
Holding
Register )
Status Affected: None
Example 1:
TBLWT *+;
Encoding:
0000
0000
0000
11nn
nn = 0 *
=1 *+
=2 *-
=3 +*
Before Instruction
TABLAT
=
0x55
TBLPTR
HOLDING REGISTER
(0x00A356)
=
0x00A356
=
0xFF
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.
After Instructions (table write completion)
TABLAT
TBLPTR
=
=
0x55
0x00A357
HOLDING REGISTER
(0x00A356)
=
0x55
Example 2:
Before Instruction
TBLWT +*;
TABLAT
TBLPTR
=
=
0x34
0x01389A
HOLDING REGISTER
(0x01389A)
HOLDING REGISTER
(0x01389B)
=
=
0xFF
0xFF
TBLPTR[0] = 0: Least Significant Byte
of Program Memory
After Instruction (table write completion)
TABLAT
TBLPTR
=
=
0x34
0x01389B
Word
TBLPTR[0] = 1: Most Significant Byte
of Program Memory
HOLDING REGISTER
(0x01389A)
HOLDING REGISTER
(0x01389B)
=
=
0xFF
0x34
Word
The TBLWT instruction can modify the
value of TBLPTR as follows:
•
•
•
•
no change
post-increment
post-decrement
pre-increment
DS39616C-page 328
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TSTFSZ
Test f, Skip if 0
XORLW
Exclusive OR Literal with W
Syntax:
[ label ] TSTFSZ f [,a]
Syntax:
[ label ] XORLW
0 ≤ k ≤ 255
k
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operands:
Operation:
Status Affected:
Encoding:
Description:
(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 will be selected,
overriding the BSR value. If ‘a’ is ‘1’,
then the bank will be selected as per
the BSR value (default).
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to W
Words:
Cycles:
1
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Example:
XORLW 0xAF
= 0xB5
Before Instruction
Q Cycle Activity:
Q1
W
Q2
Q3
Q4
After Instruction
Decode
Read
register ‘f’
Process
Data
No
operation
W
=
0x1A
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
:
:
Before Instruction
PC = Address (HERE)
After Instruction
If CNT
=
=
≠
=
0x00,
Address (ZERO)
0x00,
PC
If CNT
PC
Address (NZERO)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 329
PIC18F2331/2431/4331/4431
XORWF
Exclusive OR W with f
Syntax:
[ label ] 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 will be selected, over-
riding the BSR value. If ‘a’ is ‘1’, then
the bank will be selected as per the
BSR value (default).
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
XORWF
REG
Before Instruction
REG
W
=
=
0xAF
0xB5
After Instruction
REG
W
=
=
0x1A
0xB5
DS39616C-page 330
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
24.1 MPLAB Integrated Development
Environment Software
24.0 DEVELOPMENT SUPPORT
The PIC® 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®
operating system-based application that contains:
• Integrated Development Environment
- MPLAB® IDE Software
• Assemblers/Compilers/Linkers
- MPASMTM Assembler
• A single graphical interface to all debugging tools
- Simulator
- MPLAB C18 and MPLAB C30 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 ASM30 Assembler/Linker/Library
• Simulators
- MPLAB SIM Software Simulator
• Emulators
• Customizable data windows with direct edit of
contents
- MPLAB ICE 2000 In-Circuit Emulator
- MPLAB REAL ICE™ In-Circuit Emulator
• In-Circuit Debugger
• High-level source code debugging
• Visual device initializer for easy register
initialization
- MPLAB ICD 2
• Mouse over variable inspection
• Device Programmers
• Drag and drop variables from source to watch
windows
- PICSTART® Plus Development Programmer
- MPLAB PM3 Device Programmer
- PICkit™ 2 Development Programmer
• Extensive on-line help
• Integration of select third party tools, such as
HI-TECH Software C Compilers and IAR
C Compilers
• Low-Cost Demonstration and Development
Boards and Evaluation Kits
The MPLAB IDE allows you to:
• Edit your source files (either assembly or C)
• One touch assemble (or compile) and download
to PIC MCU emulator and simulator tools
(automatically updates all project information)
• 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 increased flexibility
and power.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 331
PIC18F2331/2431/4331/4431
24.2 MPASM Assembler
24.5 MPLAB ASM30 Assembler, Linker
and Librarian
The MPASM Assembler is a full-featured, universal
macro assembler for all PIC MCUs.
MPLAB ASM30 Assembler produces relocatable
machine code from symbolic assembly language for
dsPIC30F devices. MPLAB C30 C Compiler uses the
assembler to produce its 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:
The MPASM Assembler generates relocatable object
files for the MPLINK Object Linker, Intel® standard HEX
files, MAP files to detail memory usage and symbol
reference, absolute LST files that contain source lines
and generated machine code and COFF files for
debugging.
The MPASM Assembler features include:
• Integration into MPLAB IDE projects
• Support for the entire dsPIC30F instruction set
• Support for fixed-point and floating-point data
• Command line interface
• User-defined macros to streamline
assembly code
• Rich directive set
• Conditional assembly for multi-purpose
source files
• Flexible macro language
• MPLAB IDE compatibility
• Directives that allow complete control over the
assembly process
24.6 MPLAB SIM Software Simulator
24.3 MPLAB C18 and MPLAB C30
C Compilers
The MPLAB SIM Software Simulator allows code
development in a PC-hosted environment by simulat-
ing the PIC MCUs and dsPIC® DSCs on an instruction
level. On any given instruction, the data areas can be
examined or modified and stimuli can be applied from
a comprehensive stimulus controller. Registers can be
logged to files for further run-time analysis. The trace
buffer and logic analyzer display extend the power of
the simulator to record and track program execution,
actions on I/O, most peripherals and internal registers.
The MPLAB C18 and MPLAB C30 Code Development
Systems are complete ANSI
C
compilers for
Microchip’s PIC18 and PIC24 families of microcontrol-
lers and the dsPIC30 and dsPIC33 family of digital sig-
nal controllers. 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.
The MPLAB SIM Software Simulator fully supports
symbolic debugging using the MPLAB C18 and
MPLAB C30 C Compilers, and the MPASM and
MPLAB ASM30 Assemblers. The software simulator
offers the flexibility to develop and debug code outside
of the hardware laboratory environment, making it an
excellent, economical software development tool.
24.4 MPLINK Object Linker/
MPLIB Object Librarian
The MPLINK Object Linker combines relocatable
objects created by the MPASM Assembler and the
MPLAB C18 C Compiler. It can link relocatable objects
from precompiled libraries, using directives from a
linker script.
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
• Enhanced code maintainability by grouping
related modules together
• Flexible creation of libraries with easy module
listing, replacement, deletion and extraction
DS39616C-page 332
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
24.7 MPLAB ICE 2000
High-Performance
24.9 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
In-Circuit Emulator
The MPLAB ICE 2000 In-Circuit Emulator is intended
to provide the product development engineer with a
complete microcontroller design tool set for PIC
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 PIC
MCUs and can be used to develop for these and other
PIC MCUs and dsPIC DSCs. 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 step-
ping and watching variables, and 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 PIC devices.
The MPLAB ICE 2000 is a full-featured emulator
system with enhanced trace, trigger and data monitor-
ing features. Interchangeable processor modules allow
the system to be easily reconfigured for emulation of
different processors. The architecture of the MPLAB
ICE 2000 In-Circuit Emulator allows expansion to
support new PIC 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.
24.10 MPLAB PM3 Device Programmer
The MPLAB PM3 Device Programmer 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 modu-
lar, 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
PIC devices without a PC connection. It can also set
code protection in this mode. The MPLAB PM3
connects to the host PC via an RS-232 or USB cable.
The MPLAB PM3 has high-speed communications and
optimized algorithms for quick programming of large
memory devices and incorporates an SD/MMC card for
file storage and secure data applications.
24.8 MPLAB REAL ICE In-Circuit
Emulator System
MPLAB REAL ICE In-Circuit Emulator System is
Microchip’s next generation high-speed emulator for
Microchip Flash DSC® and MCU devices. It debugs and
programs PIC® and dsPIC® Flash microcontrollers with
the easy-to-use, powerful graphical user interface of the
MPLAB Integrated Development Environment (IDE),
included with each kit.
The MPLAB REAL ICE probe is connected to the design
engineer’s PC using a high-speed USB 2.0 interface and
is connected to the target with either a connector
compatible with the popular MPLAB ICD 2 system
(RJ11) or with the new high speed, noise tolerant, low-
voltage differential signal (LVDS) interconnection
(CAT5).
MPLAB REAL ICE is field upgradeable through future
firmware downloads in MPLAB IDE. In upcoming
releases of MPLAB IDE, new devices will be supported,
and new features will be added, such as software break-
points and assembly code trace. MPLAB REAL ICE
offers significant advantages over competitive emulators
including low-cost, full-speed emulation, real-time
variable watches, trace analysis, complex breakpoints, a
ruggedized probe interface and long (up to three meters)
interconnection cables.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 333
PIC18F2331/2431/4331/4431
24.11 PICSTART Plus Development
Programmer
24.13 Demonstration, Development and
Evaluation Boards
The PICSTART Plus Development Programmer is an
easy-to-use, low-cost, prototype programmer. It
connects 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 PIC devices in DIP packages 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.
A wide variety of demonstration, development and
evaluation boards for various PIC MCUs and dsPIC
DSCs allows quick application development on fully func-
tional systems. Most boards include prototyping areas for
adding custom circuitry and provide application firmware
and source code for examination and modification.
The boards support a variety of features, including LEDs,
temperature sensors, switches, speakers, RS-232
interfaces, LCD displays, potentiometers and additional
EEPROM memory.
The demonstration and development boards can be
used in teaching environments, for prototyping custom
circuits and for learning about various microcontroller
applications.
24.12 PICkit 2 Development Programmer
The PICkit™ 2 Development Programmer is a low-cost
programmer and selected Flash device debugger with
an easy-to-use interface for programming many of
Microchip’s baseline, mid-range and PIC18F families of
Flash memory microcontrollers. The PICkit 2 Starter Kit
includes a prototyping development board, twelve
sequential lessons, software and HI-TECH’s PICC™
Lite C compiler, and is designed to help get up to speed
quickly using PIC® microcontrollers. The kit provides
everything needed to program, evaluate and develop
applications using Microchip’s powerful, mid-range
Flash memory family of microcontrollers.
In addition to the PICDEM™ and dsPICDEM™ demon-
stration/development board series of circuits, Microchip
has a line of evaluation kits and demonstration software
®
for analog filter design, KEELOQ security ICs, CAN,
IrDA®, PowerSmart® battery management, SEEVAL®
evaluation system, Sigma-Delta ADC, flow rate
sensing, plus many more.
Check the Microchip web page (www.microchip.com)
and the latest “Product Selector Guide” (DS00148) for
the complete list of demonstration, development and
evaluation kits.
DS39616C-page 334
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
25.0 ELECTRICAL CHARACTERISTICS
(†)
Absolute Maximum Ratings
Ambient temperature under bias.............................................................................................................-55°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
Voltage on RA4 with respect to Vss............................................................................................................... 0V to +8.5V
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 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 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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 335
PIC18F2331/2431/4331/4431
FIGURE 25-1:
PIC18F2331/2431/4331/4431 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL)
6.0V
5.5V
5.0V
4.5V
4.0V
PIC18F2X31/4X31
4.2V
3.5V
3.0V
2.5V
2.0V
40 MHz
Frequency
FIGURE 25-2:
PIC18LF2331/2431/4331/4431 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL)
6.0V
5.5V
5.0V
4.5V
4.0V
PIC18LF2X31/4X31
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 PIC® device in the application.
DS39616C-page 336
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
25.1 DC Characteristics: Supply Voltage
PIC18F2331/2431/4331/4431 (Industrial, Extended)
PIC18LF2331/2431/4331/4431 (Industrial)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial, Extended)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
Param
No.
Symbol
Characteristic
Supply Voltage
Min
Typ
Max Units
Conditions
VDD
D001
PIC18LF2X31/4X31 2.0
PIC18F2X31/4X31 4.2
—
—
—
5.5
5.5
—
V
V
V
HS, XT, RC and LP Oscillator mode
D002
D003
VDR
RAM Data Retention
Voltage
1.5
(1)
VPOR
VDD Start Voltage
to ensure internal
—
—
—
0.7
—
V
See section on Power-on Reset for details
Power-on Reset signal
D004
SVDD
VBOR
VDD Rise Rate
0.05
V/ms See section on Power-on Reset for details
to ensure internal
Power-on Reset signal
Date Codes from 0401xxx to 0420xxx, inclusive
Brown-out Reset Voltage
PIC18LF2X31/4X31 Industrial Low Voltage (-40°C to +85°C)
D005A
BORV1:BORV0 = 11
BORV1:BORV0 = 10
BORV1:BORV0 = 01
BORV1:BORV0 = 00
N/A
2.45
3.80
4.09
N/A
N/A
V
V
V
V
Reserved
2.72 2.99
4.22 4.64
4.54 4.99
D005B
D005C
Legend:
PIC18F2X31/4X31 Industrial (-40°C to +85°C)
BORV1:BORV0 = 1x
BORV1:BORV0 = 01
BORV1:BORV0 = 00
N/A
3.80
4.09
N/A
N/A
V
V
V
Reserved
(Note 2)
(Note 2)
4.22 4.64
4.54 4.99
PIC18F2X31/4X31 Extended (-40°C to +125°C)
BORV1:BORV0 = 1x
BORV1:BORV0 = 01
BORV1:BORV0 = 00
N/A
3.80
4.09
N/A
N/A
V
V
V
Reserved
(Note 2)
(Note 2)
4.22 4.64
4.54 4.99
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.
2: When BOR is on and BORV<1:0> = 0x, the device will operate correctly at 40 MHz for any VDD at which the BOR allows
execution.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 337
PIC18F2331/2431/4331/4431
25.1 DC Characteristics: Supply Voltage
PIC18F2331/2431/4331/4431 (Industrial, Extended)
PIC18LF2331/2431/4331/4431 (Industrial) (Continued)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial, Extended)
Operating temperature
Min Typ Max Units
-40°C ≤ TA ≤ +85°C for industrial
Param
Symbol
Characteristic
Conditions
No.
Date Codes from 0421xxx and higher
Brown-out Reset Voltage
PIC18LF2X31/4X31 Industrial Low Voltage (-10°C to +85°C)
VBOR
D005D
BORV1:BORV0 = 11
BORV1:BORV0 = 10
BORV1:BORV0 = 01
BORV1:BORV0 = 00
N/A
2.50
3.88
4.18
N/A
N/A
V
V
V
V
Reserved
2.72 2.94
4.22 4.56
4.54 4.90
D005F
PIC18LF2X31/4X31 Industrial Low Voltage (-40°C to -10°C)
BORV1:BORV0 = 11
BORV1:BORV0 = 10
BORV1:BORV0 = 01
BORV1:BORV0 = 00
N/A
2.34
3.63
3.90
N/A
N/A
V
V
V
V
Reserved
2.72 3.10
4.22 4.81
4.54 5.18
D005G
D005H
D005J
PIC18F2X31/4X31 Industrial (-10°C to +85°C)
BORV1:BORV0 = 1x
BORV1:BORV0 = 01
BORV1:BORV0 = 00
N/A
3.88
4.18
N/A
N/A
V
V
V
Reserved
(Note 2)
(Note 2)
4.22 4.56
4.54 4.90
PIC18F2X31/4X31 Industrial (-40°C to -10°C)
BORV1:BORV0 = 1x
BORV1:BORV0 = 01
BORV1:BORV0 = 00
N/A
N/A
3.90
N/A
N/A
N/A
N/A
V
V
V
Reserved
Reserved
(Note 2)
4.54 5.18
PIC18F2X31/4X31 Extended (-10°C to +85°C)
BORV1:BORV0 = 1x
BORV1:BORV0 = 01
BORV1:BORV0 = 00
N/A
3.88
4.18
N/A
N/A
V
V
V
Reserved
(Note 2)
(Note 2)
4.22 4.56
4.54 4.90
D005K
PIC18F2X31/4X31 Extended (-40°C to -10°C, +85°C to +125°C)
BORV1:BORV0 = 1x
BORV1:BORV0 = 01
BORV1:BORV0 = 00
N/A
N/A
3.90
N/A
N/A
N/A
N/A
V
V
V
Reserved
Reserved
(Note 2)
4.54 5.18
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.
2: When BOR is on and BORV<1:0> = 0x, the device will operate correctly at 40 MHz for any VDD at which the BOR allows
execution.
DS39616C-page 338
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
25.2 DC Characteristics: Power-Down and Supply Current
PIC18F2331/2431/4331/4431 (Industrial, Extended)
PIC18LF2331/2431/4331/4431 (Industrial)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial, Extended)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
Param
Device
No.
Typ
Max Units
Conditions
(1)
Power-Down Current (IPD)
PIC18LF2X31/4X31 0.1
0.5
0.5
1.9
0.5
0.5
1.9
2.0
2.0
6.5
μA
μA
μA
μA
μA
μA
μA
μA
μA
-40°C
+25°C
VDD = 2.0V
(Sleep mode)
0.1
0.2
+85°C
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
PIC18LF2X31/4X31 0.1
VDD = 3.0V
(Sleep mode)
0.1
0.3
All devices 0.1
VDD = 5.0V
(Sleep mode)
0.1
0.4
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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 339
PIC18F2331/2431/4331/4431
25.2 DC Characteristics: Power-Down and Supply Current
PIC18F2331/2431/4331/4431 (Industrial, Extended)
PIC18LF2331/2431/4331/4431 (Industrial) (Continued)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial, Extended)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
Param
Device
No.
Typ
Max Units
Conditions
(2,3)
Supply Current (IDD)
PIC18LF2X31/4X31
PIC18LF2X31/4X31
All devices
8
40
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
mA
mA
mA
-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
-40°C
+25°C
+85°C
-40°C
+25°C
+85°C
9
40
VDD = 2.0V
11
25
25
20
55
55
50
40
68
FOSC = 31 kHz
(RC_RUN mode,
Internal oscillator source)
68
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
68
180
180
180
220
220
220
330
330
330
550
550
550
600
600
600
900
900
900
1.8
PIC18LF2X31/4X31 140
145
155
PIC18LF2X31/4X31 215
FOSC = 1 MHz
(RC_RUN mode,
Internal oscillator source)
225
235
All devices 385
390
405
PIC18LF2X31/4X31 410
425
435
PIC18LF2X31/4X31 650
FOSC = 4 MHz
(RC_RUN mode,
Internal oscillator source)
670
680
All devices 1.2
1.2
1.2
1.8
1.8
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.
DS39616C-page 340
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
25.2 DC Characteristics: Power-Down and Supply Current
PIC18F2331/2431/4331/4431 (Industrial, Extended)
PIC18LF2331/2431/4331/4431 (Industrial) (Continued)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial, Extended)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
Param
Device
No.
Typ
Max Units
Conditions
(2,3)
Supply Current (IDD)
PIC18LF2X31/4X31 4.7
8
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
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
-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
5.0
8
VDD = 2.0V
5.8
11
PIC18LF2X31/4X31 7.0
11
FOSC = 31 kHz
7.8
8.7
11
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
(RC_IDLE mode,
Internal oscillator source)
15
All devices
12
14
14
75
85
95
16
16
22
PIC18LF2X31/4X31
150
150
150
180
180
180
300
300
300
275
275
275
375
375
375
800
800
800
PIC18LF2X31/4X31 110
FOSC = 1 MHz
(RC_IDLE mode,
Internal oscillator source)
125
135
All devices 180
195
200
PIC18LF2X31/4X31 175
185
195
PIC18LF2X31/4X31 265
FOSC = 4 MHz
(RC_IDLE mode,
Internal oscillator source)
280
300
All devices 475
500
505
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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 341
PIC18F2331/2431/4331/4431
25.2 DC Characteristics: Power-Down and Supply Current
PIC18F2331/2431/4331/4431 (Industrial, Extended)
PIC18LF2331/2431/4331/4431 (Industrial) (Continued)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial, Extended)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
Param
Device
No.
Typ
Max Units
Conditions
(2,3)
Supply Current (IDD)
PIC18LF2X31/4X31 150
250
250
250
350
350
350
1.0
1.0
1.0
600
600
600
1.0
1.0
1.0
2.0
2.0
2.0
12
μA
μA
-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
-40°C
+25°C
+85°C
150
VDD = 2.0V
160
μA
PIC18LF2X31/4X31 340
μA
FOSC = 1 MHZ
300
μA
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
VDD = 4.2V
VDD = 5.0V
(PRI_RUN,
EC oscillator)
280
μA
All devices 0.72
mA
mA
mA
μA
0.63
0.57
PIC18LF2X31/4X31 440
450
μA
460
μA
PIC18LF2X31/4X31 0.80
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
FOSC = 4 MHz
(PRI_RUN,
EC oscillator)
0.78
0.77
All devices 1.6
1.5
1.5
All devices 9.5
9.7
12
FOSC = 40 MHZ
(PRI_RUN,
EC oscillator)
9.9
All devices 11.9
12.1
12
15
15
12.3
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.
DS39616C-page 342
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
25.2 DC Characteristics: Power-Down and Supply Current
PIC18F2331/2431/4331/4431 (Industrial, Extended)
PIC18LF2331/2431/4331/4431 (Industrial) (Continued)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial, Extended)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
Param
Device
No.
Typ
Max Units
Conditions
(2,3)
Supply Current (IDD)
PIC18LF2X31/4X31
35
35
35
55
50
60
50
50
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
mA
mA
mA
mA
mA
mA
-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
-40°C
+25°C
+85°C
VDD = 2.0V
60
PIC18LF2X31/4X31
80
FOSC = 1 MHz
80
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
VDD = 4.2 V
(PRI_IDLE mode,
EC oscillator)
100
150
150
150
180
180
180
280
280
280
525
525
525
4.1
4.1
4.1
5.1
5.1
5.1
All devices 105
110
115
PIC18LF2X31/4X31 135
140
140
PIC18LF2X31/4X31 215
FOSC = 4 MHz
(PRI_IDLE mode,
EC oscillator)
225
230
All devices 410
420
430
All devices 3.2
3.2
FOSC = 40 MHz
(PRI_IDLE mode,
EC oscillator)
3.3
All devices 4.0
4.1
4.1
VDD = 5.0V
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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 343
PIC18F2331/2431/4331/4431
25.2 DC Characteristics: Power-Down and Supply Current
PIC18F2331/2431/4331/4431 (Industrial, Extended)
PIC18LF2331/2431/4331/4431 (Industrial) (Continued)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial, Extended)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
Param
Device
No.
Typ
Max Units
Conditions
(2,3)
Supply Current (IDD)
PIC18LF2X31/4X31 5.1
9
μA
μA
μA
μA
μA
μA
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
-10°C
+25°C
+70°C
-10°C
+25°C
+70°C
-10°C
+25°C
+70°C
5.8
9
VDD = 2.0V
7.9
11
12
12
14
20
20
25
15
15
18
30
30
35
80
80
85
PIC18LF2X31/4X31 7.9
(4)
FOSC = 32 kHz
8.9
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
(SEC_RUN mode,
Timer1 as clock)
10.5
All devices 12.5
16.3
18.9
PIC18LF2X31/4X31 9.2
9.6
12.7
PIC18LF2X31/4X31 22.0
(4)
FOSC = 32 kHz
21.0
20.0
(SEC_IDLE mode,
Timer1 as clock)
All devices
30
45
45
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.
DS39616C-page 344
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
25.2 DC Characteristics: Power-Down and Supply Current
PIC18F2331/2431/4331/4431 (Industrial, Extended)
PIC18LF2331/2431/4331/4431 (Industrial) (Continued)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
PIC18F2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
(Industrial, Extended)
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
Param
Device
No.
Typ
Max Units
Conditions
Module Differential Currents (ΔIWDT, ΔIBOR, ΔILVD, ΔIOSCB, ΔIAD)
D022
(ΔIWDT)
Watchdog Timer 1.5
4.0
4.0
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
μA
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
2.2
3.1
2.5
3.3
4.7
3.7
4.5
6.1
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
5.0
6.0
6.0
7.0
10.0
10.0
13.0
35.0
45.0
25.0
35.0
45.0
3.5
D022A
(ΔIBOR)
Brown-out Reset
19
24
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C
VDD = 3.0V
VDD = 5.0V
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
D022B
(ΔILVD)
Low-Voltage Detect 8.5
16
20
D025
(ΔIOSCB)
Timer1 Oscillator 1.7
(4)
(4)
1.8
3.5
+25°C
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
32 kHz on Timer1
32 kHz on Timer1
32 kHz on Timer1
2.1
4.5
+85°C
2.2
4.5
-40°C
2.6
4.5
+25°C
2.8
5.5
+85°C
3.0
6.0
-40°C
(4)
3.3
6.0
+25°C
3.6
7.0
+85°C
D026
(ΔIAD)
A/D Converter 1.0
3.0
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
VDD = 2.0V
VDD = 3.0V
VDD = 5.0V
1.0
2.0
4.0
A/D on, not converting
10.0
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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 345
PIC18F2331/2431/4331/4431
25.3 DC Characteristics: PIC18F2331/2431/4331/4431 (Industrial)
PIC18LF2331/2431/4331/4431 (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
VIH
IIL
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
MCLR
VSS
VSS
0.2 VDD
0.3 VDD
V
V
D032A
OSC1 and T1OSI
LP, XT, HS, HSPLL
modes(1)
EC mode(1)
D033
OSC1
VSS
0.2 VDD
V
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
MCLR
0.8 VDD
0.7 VDD
VDD
VDD
V
V
D042A
OSC1 and T1OSI
LP, XT, HS, HSPLL
modes(1)
EC mode(1)
D043
D060
OSC1
0.8 VDD
—
VDD
V
Input Leakage Current(2,3)
I/O Ports
±1
μA VSS ≤ VPIN ≤ VDD,
Pin at high-impedance
D061
D063
MCLR
—
—
±1
±1
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
PIC® 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.
DS39616C-page 346
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
25.3 DC Characteristics: PIC18F2331/2431/4331/4431 (Industrial)
PIC18LF2331/2431/4331/4431 (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
VOD
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
D150
I/O Ports
VDD – 0.7
VDD – 0.7
—
—
—
V
V
V
IOH = -3.0 mA, VDD = 4.5V,
-40°C to +85°C
OSC2/CLKO
(RC, RCIO, EC, ECIO modes)
IOH = -1.3 mA, VDD = 4.5V,
-40°C to +85°C
Open-Drain High Voltage
8.5
RA4 pin
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
PIC® 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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 347
PIC18F2331/2431/4331/4431
TABLE 25-1: 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
D112
D113
VPP
IPP
Voltage on MCLR/VPP pin
Current into MCLR/VPP pin
9.00
—
—
—
—
13.25
300
1
V
(Note 3)
μA
mA
IDDP
Supply Current during
Programming
—
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 Low-Voltage Programming is disabled.
DS39616C-page 348
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 25-3:
LOW-VOLTAGE DETECT CHARACTERISTICS
VDD
(LVDIF can be
cleared in software)
VLVD
(LVDIF set by hardware)
LVDIF
TABLE 25-2: LOW-VOLTAGE DETECT CHARACTERISTICS
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
(Industrial)
Standard Operating Conditions (unless otherwise stated)
PIC18F2331/2431/4331/4431
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
(Industrial, Extended)
Param
Symbol
No.
Characteristic
Min
Typ†
Max
Units
Conditions
Date Codes from 0401xxx to 0420xxx, inclusive
LVD Voltage on VDD Transition High-to-Low Industrial Low Voltage (-40°C to +85°C)
D420A VLVD
PIC18LF2X31/4X31 LVDL<3:0> = 0000
LVDL<3:0> = 0001
N/A
N/A
N/A
N/A
N/A
N/A
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
Reserved
Reserved
LVDL<3:0> = 0010
2.08
2.26
2.35
2.55
2.64
2.82
3.09
3.29
3.38
3.56
3.75
3.93
4.23
2.26
2.45
2.55
2.77
2.87
3.07
3.36
3.57
3.67
3.87
4.07
4.28
4.60
2.44
2.65
2.76
2.99
3.10
3.31
3.63
3.86
3.96
4.18
4.40
4.62
4.96
LVDL<3:0> = 0011
LVDL<3:0> = 0100
LVDL<3:0> = 0101
LVDL<3:0> = 0110
LVDL<3:0> = 0111
LVDL<3:0> = 1000
LVDL<3:0> = 1001
LVDL<3:0> = 1010
LVDL<3:0> = 1011
LVDL<3:0> = 1100
LVDL<3:0> = 1101
LVDL<3:0> = 1110
D420B VLVD
LVD Voltage on VDD Transition High-to-Low
PIC18F2X31/4X31 LVDL<3:0> = 1011
LVDL<3:0> = 1100
Industrial (-40°C to +85°C)
3.56
3.75
3.93
4.23
3.87
4.07
4.28
4.60
4.18
4.40
4.62
4.96
V
V
V
V
LVDL<3:0> = 1101
LVDL<3:0> = 1110
Legend:
Shading of rows is to assist in readability of the table.
Production tested at TAMB = 25°C. Specifications over temperature limits ensured by characterization.
†
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 349
PIC18F2331/2431/4331/4431
TABLE 25-2: LOW-VOLTAGE DETECT CHARACTERISTICS (CONTINUED)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
(Industrial)
Standard Operating Conditions (unless otherwise stated)
PIC18F2331/2431/4331/4431
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
(Industrial, Extended)
Param
Symbol
No.
Characteristic
Min
Typ†
Max
Units
Conditions
D420C VLVD
LVD Voltage on VDD Transition High-to-Low
PIC18F2X31/4X31 LVDL<3:0> = 1011
LVDL<3:0> = 1100
Extended (-40°C to +125°C)
3.41
3.58
3.77
4.04
3.87
4.07
4.28
4.60
4.33
4.56
4.79
5.15
V
V
V
V
LVDL<3:0> = 1101
LVDL<3:0> = 1110
Date Codes from 0421xxx and higher
D420D VLVD
LVD Voltage on VDD Transition High-to-Low
PIC18LF2X31/4X31 LVDL<3:0> = 0000
LVDL<3:0> = 0001
Industrial Low Voltage (-10°C to +85°C)
N/A
N/A
N/A
N/A
N/A
N/A
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
Reserved
Reserved
LVDL<3:0> = 0010
2.08
2.26
2.35
2.55
2.64
2.82
3.09
3.29
3.38
3.56
3.75
3.93
4.23
2.26
2.45
2.55
2.77
2.87
3.07
3.36
3.57
3.67
3.87
4.07
4.28
4.60
2.44
2.65
2.76
2.99
3.10
3.31
3.63
3.86
3.96
4.18
4.40
4.62
4.96
LVDL<3:0> = 0011
LVDL<3:0> = 0100
LVDL<3:0> = 0101
LVDL<3:0> = 0110
LVDL<3:0> = 0111
LVDL<3:0> = 1000
LVDL<3:0> = 1001
LVDL<3:0> = 1010
LVDL<3:0> = 1011
LVDL<3:0> = 1100
LVDL<3:0> = 1101
LVDL<3:0> = 1110
D420F VLVD
LVD Voltage on VDD Transition High-to-Low
PIC18LF2X31/4X31 LVDL<3:0> = 0000
LVDL<3:0> = 0001
Industrial Low Voltage (-40°C to -10°C)
N/A
N/A
N/A
N/A
N/A
N/A
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
Reserved
Reserved
LVDL<3:0> = 0010
1.99
2.16
2.25
2.43
2.53
2.70
2.96
3.14
3.23
3.41
3.58
3.76
4.04
2.26
2.45
2.55
2.77
2.87
3.07
3.36
3.57
3.67
3.87
4.07
4.28
4.60
2.53
2.75
2.86
3.10
3.21
3.43
3.77
4.00
4.11
4.34
4.56
4.79
5.15
LVDL<3:0> = 0011
LVDL<3:0> = 0100
LVDL<3:0> = 0101
LVDL<3:0> = 0110
LVDL<3:0> = 0111
LVDL<3:0> = 1000
LVDL<3:0> = 1001
LVDL<3:0> = 1010
LVDL<3:0> = 1011
LVDL<3:0> = 1100
LVDL<3:0> = 1101
LVDL<3:0> = 1110
Legend:
Shading of rows is to assist in readability of the table.
Production tested at TAMB = 25°C. Specifications over temperature limits ensured by characterization.
†
DS39616C-page 350
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 25-2: LOW-VOLTAGE DETECT CHARACTERISTICS (CONTINUED)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
(Industrial)
Standard Operating Conditions (unless otherwise stated)
PIC18F2331/2431/4331/4431
Operating temperature
-40°C ≤ TA ≤ +85°C for industrial
-40°C ≤ TA ≤ +125°C for extended
(Industrial, Extended)
Param
Symbol
No.
Characteristic
Min
Typ†
Max
Units
Conditions
Date Codes from 0421xxx and higher
LVD Voltage on VDD Transition High-to-Low Industrial (-10°C to +85°C)
D420G VLVD
D420H VLVD
PIC18F2X31/4X31 LVDL<3:0> = 1101
LVDL<3:0> = 1110
3.93
4.23
4.28
4.60
4.62
4.96
V
V
LVD Voltage on VDD Transition High-to-Low
PIC18F2X31/4X31 LVDL<3:0> = 1101
LVDL<3:0> = 1110
Industrial (-40°C to -10°C)
3.76
4.04
4.28
4.60
4.79
5.15
V
V
Reserved
D420J
VLVD
LVD Voltage on VDD Transition High-to-Low
PIC18F2X31/4X31 LVDL<3:0> = 1101
LVDL<3:0> = 1110
Extended (-10°C to +85°C)
3.94
4.23
4.28
4.60
4.62
4.96
V
V
D420K VLVD
LVD Voltage on VDD Transition High-to-Low
PIC18F2X31/4X31 LVDL<3:0> = 1101
LVDL<3:0> = 1110
Extended (-40°C to -10°C, +85°C to +125°C)
3.77
4.05
4.28
4.60
4.79
5.15
V
V
Reserved
Legend:
Shading of rows is to assist in readability of the table.
Production tested at TAMB = 25°C. Specifications over temperature limits ensured by characterization.
†
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 351
PIC18F2331/2431/4331/4431
25.4 AC (Timing) Characteristics
25.4.1
TIMING PARAMETER SYMBOLOGY
The timing parameter symbols have been created
following 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
T1CKI
WR
io
t1
mc
wr
Uppercase letters and their meanings:
S
F
Fall
P
R
V
Z
Period
H
High
Rise
I
Invalid (High-Impedance)
Low
Valid
L
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
DS39616C-page 352
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
25.4.2
TIMING CONDITIONS
Note: Because of space limitations, the generic
terms “PIC18FXX31” and “PIC18LFXX31”
The temperature and voltages specified in Table 25-3
apply to all timing specifications unless otherwise
noted. Figure 25-4 specifies the load conditions for the
timing specifications.
are used throughout this section to refer to
the PIC18F2331/2431/4331/4431 and
PIC18LF2331/2431/4331/4431 families of
devices specifically, and only those
devices.
TABLE 25-3: TEMPERATURE AND VOLTAGE SPECIFICATIONS – AC
Standard Operating Conditions (unless otherwise stated)
Operating temperature
Operating voltage VDD range as described in DC spec Section 25.1 and
Section 25.3. LF parts operate for industrial temperatures only.
-40°C ≤ TA ≤ +85°C for industrial
AC CHARACTERISTICS
FIGURE 25-4:
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
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 353
PIC18F2331/2431/4331/4431
25.4.3
TIMING DIAGRAMS AND SPECIFICATIONS
FIGURE 25-5:
EXTERNAL CLOCK TIMING (ALL MODES EXCEPT PLL)
Q4
Q1
1
Q2
Q3
Q4
Q1
OSC1
CLKO
3
4
3
4
2
TABLE 25-4: 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
MHz RC osc
MHz XT osc
MHz HS osc
4
25
4
10
MHz HS + PLL osc
kHz LP Osc mode
5
200
—
1
TOSC
External CLKI Period(1)
Oscillator Period(1)
25
250
250
ns
ns
ns
EC, ECIO
RC osc
XT osc
—
10,000
25
100
250
250
ns
ns
HS osc
HS + PLL osc
25
100
30
2.5
10
—
—
—
μs
ns
ns
μs
ns
ns
ns
ns
LP osc
2
3
TCY
Instruction Cycle Time(1)
TCY = 4/FOSC
XT osc
TosL,
TosH
External Clock in (OSC1)
High or Low Time
—
—
LP osc
—
HS osc
XT osc
4
TosR,
TosF
External Clock in (OSC1)
Rise or Fall Time
20
50
7.5
—
LP osc
—
HS osc
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.
DS39616C-page 354
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 25-5: 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
FSYS On-Chip VCO System Frequency
TPLL PLL Start-up Time (Lock Time)
ΔCLK CLKO Stability (Jitter)
4
—
—
—
—
10
40
2
MHz HS mode only
16
—
-2
MHz HS mode only
ms
%
+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 25-6: INTERNAL RC ACCURACY: PIC18F2331/2431/4331/4431 (INDUSTRIAL)
PIC18LF2331/2431/4331/4431 (INDUSTRIAL)
PIC18LF2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
(Industrial)
PIC18F2331/2431/4331/4431
Standard Operating Conditions (unless otherwise stated)
Operating temperature -40°C ≤ TA ≤ +85°C for industrial
(Industrial)
Param
Device
No.
Min
Typ
Max
Units
Conditions
(1)
INTOSC Accuracy @ Freq = 8 MHz, 4 MHz, 2 MHz, 1 MHz, 500 kHz, 250 kHz, 125 kHz
F2
F3
PIC18LF2331/2431/4331/4431
All devices
-15
+/-5
+/-5
+15
+15
%
%
25°C
25°C
VDD = 3.0V
VDD = 5.0V
-15
(2)
INTRC Accuracy @ Freq = 31 kHz
F5
F6
PIC18LF2331/2431/4331/4431 26.562
All devices 26.562
—
—
35.938
35.938
kHz
kHz
25°C
25°C
VDD = 3.0V
VDD = 5.0V
(3)
INTRC Stability
F8
PIC18LF2331/2431/4331/4431
All devices
TBD
TBD
1
1
TBD
TBD
%
%
25°C
25°C
VDD = 3.0V
VDD = 5.0V
F9
Legend:
TBD = To Be Determined. 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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 355
PIC18F2331/2431/4331/4431
FIGURE 25-6:
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
Refer to Figure 25-4 for load conditions.
Note:
TABLE 25-7: 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 (Note 1)
ns (Note 1)
ns (Note 1)
ns (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 (Note 1)
0.25 TCY + 25
—
—
ns (Note 1)
0
ns (Note 1)
—
150
—
ns
ns
ns
TosH2ioI OSC1 ↑ (Q2 cycle) to
Port Input Invalid
PIC18FXX31
PIC18LFXX31
100
200
—
(I/O in hold time)
19
TioV2osH Port Input Valid to OSC1 ↑ (I/O in setup
0
—
—
ns
time)
20
TioR
TioF
Port Output Rise Time
Port Output Fall Time
PIC18FXX31
PIC18LFXX31
PIC18FXX31
PIC18LFXX31
—
—
10
—
10
—
—
—
25
60
25
60
—
—
ns
ns
ns
ns
ns
ns
ns
20A
21
—
21A
22†
23†
24†
—
TINP
INTx Pin High or Low Time
TCY
TCY
20
TRBP
TRCP
RB7:RB4 Change INTx High or Low Time
RB7:RB4 Change INTx 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.
DS39616C-page 356
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 25-7:
RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND POWER-UP
TIMER TIMING
VDD
MCLR
30
Internal
POR
33
PWRT
Time-out
32
Oscillator
Time-out
Internal
Reset
Watchdog
Timer Reset
31
34
34
I/O Pins
Note:
Refer to Figure 25-4 for load conditions.
FIGURE 25-8:
BROWN-OUT RESET TIMING
BVDD
VDD
35
VBGAP = 1.2V
VIRVST
Enable Internal
Reference Voltage
Internal Reference
Voltage Stable
36
TABLE 25-8: 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
TLVD
Low-Voltage Detect Pulse Width
200
—
—
μs
VDD ≤ VLVD
Legend: TBD = To Be Determined
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 357
PIC18F2331/2431/4331/4431
FIGURE 25-9:
TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
T0CKI
41
40
42
T1OSO/T1CKI
46
45
47
48
TMR0 or TMR1
Note:
Refer to Figure 25-4 for load conditions.
TABLE 25-9: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS
Param
No.
Symbol
Characteristic
T0CKI High Pulse Width
Min
Max
Units
Conditions
40
Tt0H
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 TCY + 40
N
ns N = prescale value
(1, 2, 4,..., 256)
45
46
Tt1H
Tt1L
T1CKI High Synchronous, no prescaler
Time
0.5 TCY + 20
—
—
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Synchronous,
with prescaler
PIC18FXX31
10
PIC18LFXX31
PIC18FXX31
PIC18LFXX31
25
—
Asynchronous
30
—
50
0.5 TCY + 5
10
—
T1CKI
Synchronous, no prescaler
—
Low Time
Synchronous,
with prescaler
PIC18FXX31
—
PIC18LFXX31
PIC18FXX31
PIC18LFXX31
25
—
Asynchronous
30
—
TBD
TBD
—
47
48
Tt1P
Ft1
T1CKI Input Synchronous
Period
Greater of:
20 ns or TCY + 40
N
ns N = prescale value
(1, 2, 4, 8)
Asynchronous
60
DC
—
50
ns
kHz
—
T1CKI Oscillator Input Frequency Range
Tcke2tmrI Delay from External T1CKI Clock Edge to
Timer Increment
2 TOSC
7 TOSC
Legend: TBD = To Be Determined
DS39616C-page 358
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 25-10:
CAPTURE/COMPARE/PWM TIMINGS (ALL CCP MODULES)
CCPx
(Capture Mode)
50
51
52
54
CCPx
(Compare or PWM Mode)
53
Refer to Figure 25-4 for load conditions.
Note:
TABLE 25-10: 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
prescaler
PIC18FXX31
PIC18LFXX31
10
20
51
TccH
CCPx Input High No prescaler
0.5 TCY + 20
Time
With
prescaler
PIC18FXX31
PIC18LFXX31
10
20
52
53
TccP
TccR
CCPx Input Period
3 TCY + 40
N
N = prescale
value (1, 4 or 16)
CCPx Output Fall Time
CCPx Output Fall Time
PIC18FXX31
PIC18LFXX31
PIC18FXX31
PIC18LFXX31
—
—
—
—
25
45
25
45
ns
ns
ns
ns
54
TccF
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 359
PIC18F2331/2431/4331/4431
FIGURE 25-11:
EXAMPLE SPI MASTER MODE TIMING (CKE = 0)
SS
70
SCK
(CKP = 0)
71
72
78
79
79
78
SCK
(CKP = 1)
80
MSb
bit 6 - - - - - -1
LSb
SDO
SDI
75, 76
MSb In
74
bit 6 - - - -1
LSb In
73
Note: Refer to Figure 25-4 for load conditions.
TABLE 25-11: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 0)
Param
No.
Symbol
Characteristic
Min
Max Units Conditions
70
TssL2scH, SS ↓ to SCK ↓ or SCK ↑ Input
TCY
—
ns
TssL2scL
71
TscH
TscL
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
73
ns (Note 1)
TdiV2scH, Setup Time of SDI Data Input to SCK Edge
TdiV2scL
100
1.5 TCY + 40
100
—
—
—
ns
73A
74
TB2B
Last Clock Edge of Byte 1 to the 1st Clock Edge
of Byte 2
(Note 2)
ns
TscH2diL, Hold Time of SDI Data Input to SCK Edge
TscL2diL
ns
75
TdoR
SDO Data Output Rise Time PIC18FXX31
PIC18LFXX31
—
—
—
—
—
—
—
—
25
45
25
25
45
25
50
100
ns
ns
ns
ns
ns
ns
ns
ns
76
78
TdoF
TscR
SDO Data Output Fall Time
SCK Output Rise Time
(Master mode)
PIC18FXX31
PIC18LFXX31
79
80
TscF
SCK Output Fall Time (Master mode)
TscH2doV, SDO Data Output Valid after PIC18FXX31
TscL2doV SCK Edge
PIC18LFXX31
Note 1: Requires the use of Parameter 73A.
2: Only if Parameter 71A and 72A are used.
DS39616C-page 360
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 25-12:
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 25-4 for load conditions.
TABLE 25-12: 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, Hold Time of SDI Data Input to SCK Edge
TscL2diL
100
—
ns
75
TdoR
SDO Data Output Rise Time PIC18FXX31
PIC18LFXX31
25
45
25
25
45
25
50
100
—
ns
ns
ns
ns
ns
ns
ns
ns
ns
76
78
TdoF
TscR
SDO Data Output Fall Time
—
—
SCK Output Rise Time
(Master mode)
PIC18FXX31
PIC18LFXX31
79
80
TscF
SCK Output Fall Time (Master mode)
—
—
TscH2doV, SDO Data Output Valid after PIC18FXX31
TscL2doV SCK Edge
PIC18LFXX31
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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 361
PIC18F2331/2431/4331/4431
FIGURE 25-13:
EXAMPLE SPI SLAVE MODE TIMING (CKE = 0)
SS
70
SCK
(CKP = 0)
83
71
72
78
79
79
SCK
(CKP = 1)
78
80
MSb
LSb
SDO
SDI
bit 6 - - - - - -1
77
75, 76
MSb In
74
bit 6 - - - -1
LSb In
73
Note:
Refer to Figure 25-4 for load conditions.
TABLE 25-13: EXAMPLE SPI MODE REQUIREMENTS (SLAVE MODE, CKE = 0)
Param
No.
Symbol
Characteristic
Min
Max Units Conditions
70
TssL2scH, SS ↓ to SCK ↓ or SCK ↑ Input
TCY
—
ns
TssL2scL
71
TscH
TscL
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)
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
PIC18FXX31
PIC18LFXX31
—
25
45
25
50
25
45
25
50
100
—
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
76
77
78
TdoF
SDO Data Output Fall Time
—
10
—
TssH2doZ SS ↑ to SDO Output High-Impedance
TscR
SCK Output Rise Time (Master mode) PIC18FXX31
PIC18LFXX31
79
80
TscF
SCK Output Fall Time (Master mode)
—
—
TscH2doV, SDO Data Output Valid after SCK Edge PIC18FXX31
TscL2doV
PIC18LFXX31
83
TscH2ssH, SS ↑ after SCK Edge
1.5 TCY + 40
TscL2ssH
Note 1: Requires the use of Parameter 73A.
2: Only if Parameter 71A and 72A are used.
DS39616C-page 362
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
FIGURE 25-14:
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 25-4 for load conditions.
TABLE 25-14: EXAMPLE SPI SLAVE MODE REQUIREMENTS (CKE = 1)
Param
No.
Symbol
Characteristic
Min
Max Units Conditions
70
TssL2scH, SS ↓ to SCK ↓ or SCK ↑ Input
TCY
—
ns
TssL2scL
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
PIC18FXX31
PIC18LFXX31
—
25
45
25
50
25
45
25
50
100
50
100
—
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
76
77
78
TdoF
SDO Data Output Fall Time
—
TssH2doZ SS ↑ to SDO Output High-Impedance
10
TscR
SCK Output Rise Time
(Master mode)
PIC18FXX31
PIC18LFXX31
—
—
79
80
TscF
SCK Output Fall Time (Master mode)
—
TscH2doV, SDO Data Output Valid after SCK
TscL2doV Edge
PIC18FXX31
PIC18LFXX31
PIC18FXX31
PIC18LFXX31
—
—
82
83
TssL2doV SDO Data Output Valid after SS ↓
—
—
Edge
TscH2ssH, SS ↑ after SCK Edge
1.5 TCY + 40
TscL2ssH
Note 1: Requires the use of Parameter 73A.
2: Only if Parameter 71A and 72A are used.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 363
PIC18F2331/2431/4331/4431
FIGURE 25-15:
I2C™ BUS START/STOP BITS TIMING
SCL
91
93
90
92
SDA
Stop
Condition
Start
Condition
Note: Refer to Figure 25-4 for load conditions.
TABLE 25-15: 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
4000
600
THD:STO Stop Condition
Hold Time
4700
600
FIGURE 25-16:
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 25-4 for load conditions.
DS39616C-page 364
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 25-16: I2C™ BUS DATA REQUIREMENTS (SLAVE MODE)
Param.
No.
Symbol
Characteristic
100 kHz mode
Min
Max
Units
Conditions
Clock High Time
4.0
—
μs
PIC18FXX31 must operate at
a minimum of 1.5 MHz
100
THIGH
400 kHz mode
0.6
—
μs
PIC18FXX31 must operate at
a minimum of 10 MHz
SSP module
1.5 TCY
4.7
—
—
Clock Low Time
100 kHz mode
μs
μs
PIC18FXX31 must operate at
a minimum of 1.5 MHz
101
TLOW
400 kHz mode
1.3
—
PIC18FXX31 must operate at
a minimum of 10 MHz
SSP Module
1.5 TCY
—
—
SDA and SCL Rise
Time
100 kHz mode
400 kHz mode
1000
300
ns
ns
102
103
TR
TF
20 + 0.1 CB
CB is specified to be from
10 to 400 pF
SDA and SCL Fall
Time
100 kHz mode
400 kHz mode
—
300
300
ns
ns
20 + 0.1 CB
CB is specified to be from
10 to 400 pF
Start Condition Setup 100 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
90
TSU:STA
THD:STA
THD:DAT
TSU:DAT
TSU:STO
TAA
Time
400 kHz mode
Start Condition Hold
Time
100 kHz mode
400 kHz mode
—
After this period, the first clock
pulse is generated
91
—
Data Input Hold Time 100 kHz mode
400 kHz mode
—
106
107
92
0
0.9
—
Data Input Setup
Time
100 kHz mode
400 kHz mode
250
100
4.7
0.6
—
(Note 2)
—
Stop Condition Setup 100 kHz mode
—
Time
400 kHz mode
—
Output Valid From
Clock
100 kHz mode
400 kHz mode
100 kHz mode
400 kHz mode
3500
—
(Note 1)
109
110
—
Bus Free Time
4.7
1.3
—
Time the bus must be free
before a new transmission can
start
TBUF
—
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
2
2: A Fast mode I C bus device can be used in a Standard mode I C 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.
2
TR max. + TSU:DAT = 1000 + 250 = 1250 ns (according to the Standard mode I C bus specification) before the SCL line
is released.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 365
PIC18F2331/2431/4331/4431
FIGURE 25-17:
SSP I2C™ BUS START/STOP BITS TIMING WAVEFORMS
SCL
SDA
93
91
90
92
Stop
Condition
Start
Condition
Note: Refer to Figure 25-4 for load conditions.
TABLE 25-17: 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
2(TOSC)(BRG + 1)
ns After this period, the
first clock pulse is
generated
400 kHz mode
1 MHz mode(1) 2(TOSC)(BRG + 1)
2(TOSC)(BRG + 1)
TSU:STO Stop Condition
Setup Time
100 kHz mode
2(TOSC)(BRG + 1)
ns
400 kHz mode
1 MHz mode(1) 2(TOSC)(BRG + 1)
2(TOSC)(BRG + 1)
THD:STO Stop Condition
Hold Time
100 kHz mode
2(TOSC)(BRG + 1)
ns
400 kHz mode
2(TOSC)(BRG + 1)
1 MHz mode(1) 2(TOSC)(BRG + 1)
Note 1: Maximum pin capacitance = 10 pF for all I2C pins.
FIGURE 25-18:
SSP I2C™ BUS DATA TIMING
103
102
100
101
109
SCL
90
106
91
92
107
SDA
In
110
109
SDA
Out
Note: Refer to Figure 25-4 for load conditions.
DS39616C-page 366
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 25-18: SSP I2C™ BUS DATA REQUIREMENTS
Param.
No.
Symbol
Characteristic
Min
Max Units
Conditions
100
101
102
103
90
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)
—
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)
ms Only relevant for
Setup Time
Repeated Start
condition
ms
400 kHz mode
1 MHz mode(1) 2(TOSC)(BRG + 1)
2(TOSC)(BRG + 1)
—
ms
—
91
THD:STA Start Condition 100 kHz mode
2(TOSC)(BRG + 1)
—
ms After this period, the first
Hold Time
clock pulse is generated
400 kHz mode
2(TOSC)(BRG + 1)
—
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
1 MHz mode(1)
100 kHz mode
400 kHz mode
1 MHz mode(1)
100 kHz mode
400 kHz mode
0
—
0
0.9
—
ms
ns
TBD
250
TSU:DAT Data Input
Setup Time
—
ns
ns
(Note 2)
100
—
TBD
—
ns
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
110
D102
TAA
TBUF
CB
Output Valid
from Clock
100 kHz mode
400 kHz mode
1 MHz mode(1)
100 kHz mode
400 kHz mode
1 MHz mode(1)
—
—
3500
1000
—
ns
—
ns
Bus Free Time
4.7
1.3
TBD
—
—
ms Time the bus must be free
before a new transmission
—
ms
can start
ms
—
Bus Capacitive Loading
400
pF
Legend: TBD = To Be Determined
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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 367
PIC18F2331/2431/4331/4431
FIGURE 25-19:
EUSART SYNCHRONOUS TRANSMISSION (MASTER/SLAVE) TIMING
RC6/TX/CK/SS
pin
121
121
RC7/RX/DT/SDO
pin
120
Note: Refer to Figure 25-4 for load conditions.
122
TABLE 25-19: EUSART SYNCHRONOUS TRANSMISSION REQUIREMENTS
Param
Symbol
Characteristic
Min
Max
Units
Conditions
No.
120
TckH2dtV SYNC XMIT (MASTER & SLAVE)
Clock High to Data Out Valid
PIC18FXX31
PIC18LFXX31
—
—
—
—
—
—
40
100
20
ns
ns
ns
ns
ns
ns
121
122
Tckrf
Tdtrf
Clock Out Rise Time and Fall Time PIC18FXX31
(Master mode)
PIC18LFXX31
PIC18FXX31
PIC18LFXX31
50
Data Out Rise Time and Fall Time
20
50
FIGURE 25-20:
EUSART SYNCHRONOUS RECEIVE (MASTER/SLAVE) TIMING
RC6/TX/CK/SS
pin
125
RC7/RX/DT/SDO
pin
126
Note: Refer to Figure 25-4 for load conditions.
TABLE 25-20: EUSART SYNCHRONOUS RECEIVE REQUIREMENTS
Param.
Symbol
Characteristic
Min
Max
Units
Conditions
No.
125
TdtV2ckl SYNC RCV (MASTER & SLAVE)
Data Hold before CK ↓ (DT hold time)
10
15
—
—
ns
ns
126
TckL2dtl
Data Hold after CK ↓ (DT hold time)
DS39616C-page 368
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
TABLE 25-21: A/D CONVERTER CHARACTERISTICS: PIC18F2331/2431/4331/4431 (INDUSTRIAL)
PIC18LF2331/2431/4331/4431 (INDUSTRIAL)
Param
No.
Symbol
Characteristic
Min
Typ
Max
Units
Conditions
Device Supply
AVDD
Analog VDD Supply
VDD – 0.3
VSS – 0.3
—
—
VDD + 0.3
VSS + 0.3
V
V
AVSS
Analog VSS Supply
IAD
Module Current
(during conversion)
—
—
500
250
—
—
μA
μA
VDD = 5V
VDD = 2.5V
IADO
Module Current Off
—
—
1.0
μA
AC Timing Parameters
A10
A11
A12
FTHR
Throughput Rate
—
—
—
—
200
75
ksps VDD = 5V, single channel
ksps VDD < 3V, single channel
TAD
A/D Clock Period
385
1000
—
—
20,000
20,000
ns
ns
VDD = 5V
VDD = 3V
TRC
A/D Internal RC Oscillator Period
—
—
—
500
750
10000
1500
2250
20000
ns
ns
ns
PIC18F parts
PIC18LF parts
AVDD < 3.0V
(1)
A13
A14
A16
TCNV
TACQ
TTC
Conversion Time
12
12
—
—
12
—
—
TAD
TAD
(2)
(2)
Acquisition Time
2
Conversion Start from External
1/4 TCY
Reference Inputs
A20
A21
A22
A23
VREF
VREFH
VREFL
IREF
Reference Voltage for 10-Bit
Resolution (VREF+ – VREF-)
1.5
1.8
—
—
AVDD – AVSS
AVDD – AVSS
V
V
VDD ≥ 3V
VDD < 3V
Reference Voltage High
(AVDD or VREF+)
1.5V
—
AVDD
V
VDD ≥ 3V
Reference Voltage Low
(AVSS or VREF-)
AVSS
—
VREFH – 1.5V
V
Reference Current
—
—
150 μA
75 μA
—
—
VDD = 5V
VDD = 2.5V
Analog Input Characteristics
(3)
A26
A30
VAIN
ZAIN
Input Voltage
AVSS – 0.3
—
—
—
AVDD + 0.3
2.5
V
Recommended Impedance of
Analog Voltage Source
kΩ
A31
ZCHIN
Analog Channel Input Impedance
—
—
10.0
kΩ
VDD = 3.0 V
DC Performance
A41
A42
NR
Resolution
10 bits
—
—
EIL
Integral Nonlinearity
—
—
—
—
<±1
<±1
LSb VDD ≥ 3.0V
VREFH ≥ 3.0V
A43
A45
A46
A47
EIL
Differential Nonlinearity
Offset Error
—
LSb VDD ≥ 3.0V
VREFH ≥ 3.0V
EOFF
EGA
—
±0.5
<±1.5
<±1.5
LSb VDD ≥ 3.0V
VREFH ≥ 3.0V
Gain Error
±0.5
LSb VDD ≥ 3.0V
VREFH ≥ 3.0V
(4)
Monotonicity
guaranteed
—
VDD ≥ 3.0V
VREFH ≥ 3.0V
Note 1: Conversion time does not include acquisition time. See Section 20.0 “10-Bit High-Speed Analog-to-Digital Converter
(A/D) Module” for a full discussion of acquisition time requirements.
2: In Sequential modes, TACQ should be 12 TAD or greater.
3: For VDD < 2.7V and temperature below 0°C, VAIN should be limited to range < VDD/2.
4: The A/D conversion result never decreases with an increase in the input voltage and has no missing codes.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 369
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 370
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
26.0 DC AND AC
CHARACTERISTICS GRAPHS
AND TABLES
Graphs and tables are not available at this time.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 371
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 372
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
27.0 PACKAGING INFORMATION
27.1 Package Marking Information
28-Lead SPDIP (Skinny PDIP)
Example
e
3
PIC18F2331-I/SP
0710017
XXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXX
YYWWNNN
28-Lead SOIC
Example
e
3
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
PIC18F2431-E/SO
0710017
YYWWNNN
28-Lead QFN
Example
XXXXXXXX
XXXXXXXX
YYWWNNN
18F2431
-I/ML
0710017
e
3
Legend: XX...X Customer-specific information
Y
Year code (last digit of calendar year)
YY
WW
NNN
Year code (last 2 digits of calendar year)
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
e
3
Pb-free JEDEC designator for Matte Tin (Sn)
*
This package is Pb-free. The Pb-free JEDEC designator (
can be found on the outer packaging for this package.
)
e3
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.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 373
PIC18F2331/2431/4331/4431
27.1 Package Marking Information (Continued)
40-Lead PDIP
Example
e
3
XXXXXXXXXXXXXXXXXX
PIC18F4331-I/P
0710017
XXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXX
YYWWNNN
44-Lead TQFP
Example
XXXXXXXXXX
XXXXXXXXXX
XXXXXXXXXX
YYWWNNN
PIC18F4431
e
3
-I/PT
0710017
44-Lead QFN
Example
XXXXXXXXXX
XXXXXXXXXX
XXXXXXXXXX
YYWWNNN
PIC18F4431
e3
-I/ML
0710017
DS39616C-page 374
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
27.2 Package Details
The following sections give the technical details of the packages.
28-Lead Skinny Plastic Dual In-Line (SP) – 300 mil Body [SPDIP]
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
N
NOTE 1
E1
1
2 3
D
E
A2
A
L
c
b1
A1
b
e
eB
Units
INCHES
NOM
28
Dimension Limits
MIN
MAX
Number of Pins
Pitch
N
e
.100 BSC
–
Top to Seating Plane
A
–
.200
.150
–
Molded Package Thickness
Base to Seating Plane
Shoulder to Shoulder Width
Molded Package Width
Overall Length
A2
A1
E
.120
.015
.290
.240
1.345
.110
.008
.040
.014
–
.135
–
.310
.285
1.365
.130
.010
.050
.018
–
.335
.295
1.400
.150
.015
.070
.022
.430
E1
D
Tip to Seating Plane
Lead Thickness
L
c
Upper Lead Width
b1
b
Lower Lead Width
Overall Row Spacing §
eB
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. § Significant Characteristic.
3. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010" per side.
4. Dimensioning and tolerancing per ASME Y14.5M.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
Microchip Technology Drawing C04-070B
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 375
PIC18F2331/2431/4331/4431
28-Lead Plastic Small Outline (SO) – Wide, 7.50 mm Body [SOIC]
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
D
N
E
E1
NOTE 1
1
2
3
e
b
h
α
h
c
φ
A2
A
L
A1
L1
β
Units
MILLIMETERS
Dimension Limits
MIN
NOM
MAX
Number of Pins
Pitch
N
e
28
1.27 BSC
Overall Height
A
–
–
2.65
–
Molded Package Thickness
Standoff §
A2
A1
E
2.05
0.10
–
–
0.30
Overall Width
10.30 BSC
Molded Package Width
Overall Length
Chamfer (optional)
Foot Length
E1
D
h
7.50 BSC
17.90 BSC
0.25
0.40
–
0.75
1.27
L
–
Footprint
L1
φ
c
1.40 REF
Foot Angle Top
Lead Thickness
Lead Width
0°
0.18
0.31
5°
–
–
–
–
–
8°
0.33
0.51
15°
b
Mold Draft Angle Top
Mold Draft Angle Bottom
α
β
5°
15°
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. § Significant Characteristic.
3. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15 mm per side.
4. Dimensioning and tolerancing per ASME Y14.5M.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
Microchip Technology Drawing C04-052B
DS39616C-page 376
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
28-Lead Plastic Quad Flat, No Lead Package (ML) – 6x6 mm Body [QFN]
with 0.55 mm Contact Length
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
D
D2
EXPOSED
PAD
e
E
b
E2
2
1
2
1
K
N
N
NOTE 1
L
BOTTOM VIEW
TOP VIEW
A
A3
A1
Units
MILLIMETERS
NOM
Dimension Limits
MIN
MAX
Number of Pins
N
e
28
Pitch
0.65 BSC
0.90
Overall Height
Standoff
A
0.80
0.00
1.00
0.05
A1
A3
E
0.02
Contact Thickness
Overall Width
0.20 REF
6.00 BSC
3.70
Exposed Pad Width
Overall Length
Exposed Pad Length
Contact Width
Contact Length
Contact-to-Exposed Pad
E2
D
3.65
4.20
6.00 BSC
3.70
D2
b
3.65
0.23
0.50
0.20
4.20
0.35
0.70
–
0.30
L
0.55
K
–
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. Package is saw singulated.
3. Dimensioning and tolerancing per ASME Y14.5M.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
Microchip Technology Drawing C04-105B
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 377
PIC18F2331/2431/4331/4431
40-Lead Plastic Dual In-Line (P) – 600 mil Body [PDIP]
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
N
NOTE 1
E1
1 2 3
D
E
A2
A
L
c
b1
b
A1
e
eB
Units
INCHES
Dimension Limits
MIN
NOM
MAX
Number of Pins
Pitch
N
e
40
.100 BSC
Top to Seating Plane
Molded Package Thickness
Base to Seating Plane
Shoulder to Shoulder Width
Molded Package Width
Overall Length
A
–
–
–
–
–
–
–
–
–
–
–
–
.250
.195
–
A2
A1
E
.125
.015
.590
.485
1.980
.115
.008
.030
.014
–
.625
.580
2.095
.200
.015
.070
.023
.700
E1
D
Tip to Seating Plane
Lead Thickness
L
c
Upper Lead Width
b1
b
Lower Lead Width
Overall Row Spacing §
eB
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. § Significant Characteristic.
3. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010" per side.
4. Dimensioning and tolerancing per ASME Y14.5M.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
Microchip Technology Drawing C04-016B
DS39616C-page 378
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
44-Lead Plastic Thin Quad Flatpack (PT) – 10x10x1 mm Body, 2.00 mm Footprint [TQFP]
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
D
D1
E
e
E1
N
b
NOTE 1
1 2 3
NOTE 2
α
A
c
φ
A2
β
A1
L
L1
Units
MILLIMETERS
Dimension Limits
MIN
NOM
44
MAX
Number of Leads
Lead Pitch
N
e
0.80 BSC
–
Overall Height
A
–
1.20
1.05
0.15
0.75
Molded Package Thickness
Standoff
A2
A1
L
0.95
0.05
0.45
1.00
–
Foot Length
0.60
Footprint
L1
φ
1.00 REF
3.5°
Foot Angle
0°
7°
Overall Width
E
12.00 BSC
12.00 BSC
10.00 BSC
10.00 BSC
–
Overall Length
D
Molded Package Width
Molded Package Length
Lead Thickness
Lead Width
E1
D1
c
0.09
0.30
11°
0.20
0.45
13°
b
0.37
Mold Draft Angle Top
Mold Draft Angle Bottom
α
β
12°
11°
12°
13°
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. Chamfers at corners are optional; size may vary.
3. Dimensions D1 and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.25 mm per side.
4. Dimensioning and tolerancing per ASME Y14.5M.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
Microchip Technology Drawing C04-076B
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 379
PIC18F2331/2431/4331/4431
44-Lead Plastic Quad Flat, No Lead Package (ML) – 8x8 mm Body [QFN]
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
D2
D
EXPOSED
PAD
e
b
K
E
E2
2
1
2
1
N
N
NOTE 1
L
TOP VIEW
BOTTOM VIEW
A
A3
A1
Units
MILLIMETERS
Dimension Limits
MIN
NOM
44
MAX
Number of Pins
N
e
Pitch
0.65 BSC
0.90
Overall Height
Standoff
A
0.80
0.00
1.00
0.05
A1
A3
E
0.02
Contact Thickness
Overall Width
0.20 REF
8.00 BSC
6.45
Exposed Pad Width
Overall Length
Exposed Pad Length
Contact Width
Contact Length
Contact-to-Exposed Pad
E2
D
6.30
6.80
8.00 BSC
6.45
D2
b
6.30
0.25
0.30
0.20
6.80
0.38
0.50
–
0.30
L
0.40
K
–
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. Package is saw singulated.
3. Dimensioning and tolerancing per ASME Y14.5M.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
Microchip Technology Drawing C04-103B
DS39616C-page 380
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
APPENDIX A: REVISION HISTORY
APPENDIX B: DEVICE
DIFFERENCES
Revision A (June 2003)
The differences between the devices listed in this data
sheet are shown in Table B-1.
Original data sheet for PIC18F2331/2431/4331/4431
devices.
Revision B (December 2003)
The Electrical Specifications in Section 25.0 “Electri-
cal Characteristics” have been updated and there
have been minor corrections to the data sheet text.
Revision C (June 2007)
The data sheet has been updated with all known Data
Sheet Errata items and there have been minor
corrections made to the data sheet text. Also, the
packaging diagrams have been updated in
Section 27.0 “Packaging Information”.
TABLE B-1:
DEVICE DIFFERENCES
Features
PIC18F2331
PIC18F2431
PIC18F4331
PIC18F4431
Program Memory (Bytes)
Program Memory (Instructions)
Interrupt Sources
4096
2048
22
8192
4096
22
4096
2048
34
8192
4096
34
I/O Ports
Ports A, B, C, D, E Ports A, B, C, D, E Ports A, B, C, D, E Ports A, B, C, D, E
Capture/Compare/PWM Modules
2
1
2
1
2
1
2
1
Enhanced Capture/Compare/
PWM Modules
10-Bit Analog-to-Digital Module
Packages
5 Input Channels
5 Input Channels
9 Input Channels
9 Input Channels
28-Pin SPDIP
28-Pin SOIC
28-Pin QFN
28-Pin SPDIP
28-Pin SOIC
28-Pin QFN
40-Pin PDIP
44-Pin TQFP
44-Pin QFN
40-Pin PDIP
44-Pin TQFP
44-Pin QFN
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 381
PIC18F2331/2431/4331/4431
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
DS39616C-page 382
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
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
PIC18F442.” 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
differences between the high-end MCU devices (i.e.,
PIC17CXXX) and the enhanced devices (i.e.,
PIC18FXXX) is provided in AN726, “PIC17CXXX to
PIC18FXXX Migration.”
This Application Note is available on Microchip’s web
site; www.Microchip.com.
This Application Note is available on Microchip’s web
site; www.Microchip.com.
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 383
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 384
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
INDEX
On-Chip Reset Circuit................................................. 47
PIC18F2331/2431 ...................................................... 12
A
A/D.................................................................................... 245
Acquisition Requirements ......................................... 255
Associated Registers ................................................ 261
Calculating the Minimum Required
PIC18F4331/4431 ...................................................... 13
PLL ............................................................................. 24
Power Control PWM Module .................................... 182
PWM (Standard)....................................................... 157
PWM I/O Pin............................................................. 206
PWM Module, One Output Pair,
Acquisition Time ............................................... 256
Configuring................................................................ 253
Configuring Analog Port Pins.................................... 258
Conversions.............................................................. 259
Converter Characteristics ......................................... 369
Operation in Power-Managed Modes ....................... 258
Result Buffer ............................................................. 255
Selecting and Configuring Automatic
Complementary Mode ...................................... 183
PWM Module, One Output Pair,
Independent Mode ........................................... 183
PWM Time Base....................................................... 185
QEI ........................................................................... 169
RA0 Pin .................................................................... 110
RA1 Pin .................................................................... 110
RA3:RA2 Pins........................................................... 110
RA4 Pin .................................................................... 111
RA5 Pin .................................................................... 112
RA6 Pin .................................................................... 112
RA7 Pin .................................................................... 112
RB3:RB0 Pins........................................................... 115
RB4 Pin .................................................................... 116
RB5 Pin .................................................................... 117
RB7:RB6 Pins........................................................... 118
RC0 Pin .................................................................... 120
RC1 Pin .................................................................... 121
RC2 Pin .................................................................... 121
RC3 Pin .................................................................... 122
RC4 Pin .................................................................... 122
RC5 Pin .................................................................... 123
RC6 Pin .................................................................... 123
RC7 Pin .................................................................... 124
RD0 Pin .................................................................... 129
RD1 Pin .................................................................... 129
RD2 Pin .................................................................... 128
RD3 Pin .................................................................... 128
RD4 Pin .................................................................... 127
RD5 Pin .................................................................... 127
RD7:RD6 Pins .......................................................... 126
Reads from Flash Program Memory .......................... 81
RE2:RE0 Pins........................................................... 132
RE3 Pin .................................................................... 132
Acquisition Time ............................................... 257
Selecting the Conversion Clock................................ 257
Special Event Trigger (CCP)..................................... 155
Voltage References .................................................. 257
Absolute Maximum Ratings .............................................. 335
AC (Timing) Characteristics.............................................. 352
Load Conditions for Device Timing
Specifications.................................................... 353
Parameter Symbology .............................................. 352
Temperature and Voltage Specifications.................. 353
Timing Conditions ..................................................... 353
Access Bank ....................................................................... 72
ACK Pulse................................................................. 219, 221
ADDLW ............................................................................. 295
ADDWF............................................................................. 295
ADDWFC .......................................................................... 296
Analog-to-Digital Converter. See A/D.
ANDLW ............................................................................. 296
ANDWF............................................................................. 297
Application Notes
2
AN578 (Use of the SSP Module in the I C
Multi-Master Environment)................................ 213
Assembler
MPASM Assembler................................................... 332
Auto-Wake-up on Sync Break Character.......................... 237
B
Bank Select Register (BSR)................................................ 72
BC ..................................................................................... 297
BCF................................................................................... 298
BF Bit ................................................................................ 214
Block Diagrams
2
SSP (I C Mode)........................................................ 219
SSP (SPI Mode) ....................................................... 216
System Clock.............................................................. 29
Table Read Operation ................................................ 77
Table Write Operation ................................................ 78
Table Writes to Flash Program Memory..................... 83
Timer0 in 16-Bit Mode .............................................. 136
Timer0 in 8-Bit Mode ................................................ 136
Timer1 ...................................................................... 140
Timer1 (16-Bit Read/Write Mode)............................. 140
Timer2 ...................................................................... 146
Timer5 ...................................................................... 148
Velocity Measurement.............................................. 175
Watchdog Timer ....................................................... 280
BN..................................................................................... 298
BNC .................................................................................. 299
BNN .................................................................................. 299
BNOV ............................................................................... 300
BNZ .................................................................................. 300
BOR. See Brown-out Reset.
A/D............................................................................ 252
Analog Input Model................................................... 256
Capture Mode Operation .......................................... 154
Compare Mode Operation ........................................ 155
Dead-Time Control Unit for One
PWM Output Pair.............................................. 199
EUSART Receive ..................................................... 235
EUSART Transmit .................................................... 233
External Power-on Reset Circuit
(Slow VDD Power-up).......................................... 48
Fail-Safe Clock Monitor............................................. 283
Generic I/O Port........................................................ 109
Input Capture for IC1 ................................................ 161
Input Capture for IC2 and IC3................................... 162
Interrupt Logic............................................................. 94
Low-Voltage Detect (LVD) ........................................ 264
Low-Voltage Detect (LVD) with External Input.......... 264
Motion Feedback Module.......................................... 160
BOV .................................................................................. 303
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 385
PIC18F2331/2431/4331/4431
BRA...................................................................................301
Brown-out Reset (BOR) .............................................. 48, 269
BSF ...................................................................................301
BTFSC ..............................................................................302
BTFSS...............................................................................302
BTG...................................................................................303
BZ......................................................................................304
Code Protection........................................................ 269, 285
Associated Registers................................................ 285
Data EEPROM.......................................................... 288
Program Memory...................................................... 286
COMF ............................................................................... 306
Compare (CCP Module) ................................................... 155
Associated Registers................................................ 156
CCP Pin Configuration.............................................. 155
CCPR1 Register ....................................................... 155
CCPR2 Register ....................................................... 155
Software Interrupt Mode ........................................... 155
Special Event Trigger ............................................... 155
Timer1 Mode Selection............................................. 155
Computed GOTO................................................................ 65
Configuration Bits ............................................................. 269
Configuration Register Protection..................................... 288
Control Registers
EECON1 and EECON2 .............................................. 78
Conversion Considerations............................................... 382
CPFSEQ........................................................................... 306
CPFSGT ........................................................................... 307
CPFSLT............................................................................ 307
Crystal Oscillator/Ceramic Resonators............................... 23
Customer Change Notification Service............................. 393
Customer Notification Service .......................................... 393
Customer Support............................................................. 393
C
C Compilers
MPLAB C18 ..............................................................332
MPLAB C30 ..............................................................332
CALL .................................................................................304
Capture (CCP Module)......................................................154
Associated Registers ................................................156
CCP Pin Configuration..............................................154
CCPR1H:CCPR1L Registers....................................154
Prescaler...................................................................154
Software Interrupt .....................................................154
Timer1 Mode Selection .............................................154
Capture/Compare/PWM (CCP).........................................153
Capture Mode. See Capture.
CCP1 ........................................................................153
CCPR1H Register.............................................153
CCPR1L Register .............................................153
CCP2 ........................................................................153
CCPR2H Register.............................................153
CCPR2L Register .............................................153
Compare Mode. See Compare.
D
D/A Bit............................................................................... 214
Data EEPROM Memory...................................................... 87
Associated Registers.................................................. 90
EEADR Register......................................................... 87
EECON1 and EECON2 Registers.............................. 87
Operation During Code-Protect .................................. 90
Protection Against Spurious Write.............................. 89
Reading ...................................................................... 89
Using .......................................................................... 90
Write Verify................................................................. 89
Writing ........................................................................ 89
Data Memory ...................................................................... 65
General Purpose Register File ................................... 65
Map for PIC18F2331/2431/4331/4431 ....................... 66
Special Function Registers......................................... 67
DAW ................................................................................. 308
DC and AC Characteristics
Graphs and Tables ................................................... 371
DC Characteristics............................................................ 346
Power-Down and Supply Current ............................. 339
Supply Voltage ......................................................... 337
DCFSNZ ........................................................................... 309
DECF................................................................................ 308
DECFSZ ........................................................................... 309
Development Support....................................................... 331
Device Differences............................................................ 381
Device Overview................................................................... 9
Features (table) .......................................................... 11
New Core Features....................................................... 9
Other Special Features............................................... 10
Direct Addressing ............................................................... 74
Timer Resources.......................................................153
CKE Bit..............................................................................214
CKP Bit..............................................................................215
Clock Sources.....................................................................28
Effects of Power-Managed Modes..............................31
Selection Using OSCCON Register............................28
Clocking Scheme/Instruction Cycle.....................................63
CLRF.................................................................................305
CLRWDT...........................................................................305
Code Examples
Changing Between Capture Prescalers....................154
Computed GOTO Using an Offset Value....................65
Data EEPROM Read ..................................................89
Data EEPROM Refresh Routine.................................90
Data EEPROM Write ..................................................89
Erasing a Flash Program Memory Row ......................82
Fast Register Stack.....................................................62
How to Clear RAM (Bank 1) Using
Indirect Addressing .............................................73
Implementing a Real-Time Clock Using a
Timer1 Interrupt Service ...................................143
Initializing PORTA.....................................................109
Initializing PORTB.....................................................114
Initializing PORTC.....................................................120
Initializing PORTD.....................................................126
Initializing PORTE.....................................................131
Reading a Flash Program Memory Word ...................81
Saving STATUS, WREG and
BSR Registers in RAM......................................108
Writing to Flash Program Memory ........................84–85
16 x 16 Signed Multiply Routine .................................92
16 x 16 Unsigned Multiply Routine .............................92
8 x 8 Signed Multiply Routine .....................................91
8 x 8 Unsigned Multiply Routine .................................91
E
Edge Capture Mode.......................................................... 164
Electrical Characteristics .................................................. 335
Enhanced Universal Synchronous Asynchronous
Receiver Transmitter (EUSART) .............................. 223
DS39616C-page 386
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Equations
A/D Acquisition Time................................................. 255
Conversion Time for Multi-Channel Modes............... 260
Unexpected Termination of Write
Operation............................................................ 85
Write Sequence.......................................................... 83
Write Verify................................................................. 85
Writing ........................................................................ 83
FSCM. See Fail-Safe Clock Monitor.
Minimum A/D Holding Capacitor
Charging Time .................................................. 255
PWM Period for Continuous Up/Down
Count Mode ...................................................... 193
PWM Period for Free-Running Mode........................ 193
PWM Resolution ....................................................... 193
16 x 16 Signed Multiplication Algorithm...................... 92
16 x 16 Unsigned Multiplication Algorithm.................. 92
Errata .................................................................................... 7
EUSART
G
GOTO ............................................................................... 310
H
Hardware Multiplier............................................................. 91
Introduction................................................................. 91
Operation.................................................................... 91
Performance Comparison........................................... 91
HSPLL ................................................................................ 24
Asynchronous Mode ................................................. 232
Associated Registers, Receive ......................... 236
Associated Registers, Transmit ........................ 234
Auto-Wake-up on Sync Break .......................... 237
Receiver............................................................ 235
Receiving a Break Character............................ 238
Setting Up 9-Bit Mode with
I
I/O Ports ........................................................................... 109
ID Locations.............................................................. 269, 288
INCF ................................................................................. 310
INCFSZ............................................................................. 311
In-Circuit Debugger........................................................... 288
In-Circuit Serial Programming (ICSP)....................... 269, 288
Independent PWM Mode.................................................. 201
Duty Cycle Assignment ............................................ 201
Indirect Addressing
INDF and FSR Registers............................................ 73
Operation.................................................................... 73
Indirect Addressing Operation ............................................ 74
Indirect File Operand .......................................................... 65
INFSNZ............................................................................. 311
Initialization Conditions for All Registers....................... 50–55
Input Capture.................................................................... 161
Entering and Capture Timing.................................... 167
State Change............................................................ 166
Time Base Reset Summary...................................... 168
Instruction Flow/Pipelining.................................................. 63
Instruction Set
Address Detect ......................................... 235
Transmitter........................................................ 232
12-Bit Break Character Sequence .................... 238
Baud Rate Generator (BRG)..................................... 227
Associated Registers........................................ 228
Auto-Baud Rate Detect..................................... 231
Baud Rate Error, Calculating ............................ 228
Baud Rates, Asynchronous Modes .................. 228
High Baud Rate Select (BRGH Bit) .................. 227
Power-Managed Mode Operation..................... 227
Sampling........................................................... 227
Serial Port Enable (SPEN Bit)................................... 223
Synchronous Master Mode....................................... 239
Associated Registers, Receive ......................... 241
Associated Registers, Transmit ........................ 240
Reception.......................................................... 241
Transmission .................................................... 239
Synchronous Slave Mode......................................... 242
Associated Registers, Receive ......................... 243
Associated Registers, Transmit ........................ 242
Reception.......................................................... 243
External Clock Input............................................................ 25
ADDLW..................................................................... 295
ADDWF .................................................................... 295
ADDWFC.................................................................. 296
ANDLW..................................................................... 296
ANDWF .................................................................... 297
BC............................................................................. 297
BCF .......................................................................... 298
BN............................................................................. 298
BNC.......................................................................... 299
BNN.......................................................................... 299
BNOV ....................................................................... 300
BNZ .......................................................................... 300
BOV.......................................................................... 303
BRA .......................................................................... 301
BSF........................................................................... 301
BTFSC...................................................................... 302
BTFSS...................................................................... 302
BTG .......................................................................... 303
BZ............................................................................. 304
CALL......................................................................... 304
CLRF ........................................................................ 305
CLRWDT .................................................................. 305
COMF....................................................................... 306
CPFSEQ................................................................... 306
CPFSGT................................................................... 307
CPFSLT.................................................................... 307
DAW ......................................................................... 308
F
Fail-Safe Clock Monitor............................................. 269, 283
Exiting ....................................................................... 283
Interrupts in Power-Managed Modes........................ 284
POR or Wake From Sleep ........................................ 284
WDT During Oscillator Failure .................................. 283
Fail-Safe Clock Monitor (FSCM)....................................... 269
Fast Register Stack............................................................. 62
Flash Program Memory ...................................................... 77
Associated Registers .................................................. 85
Control Registers ........................................................ 78
Erase Sequence ......................................................... 82
Erasing........................................................................ 82
Operation During Code-Protect .................................. 85
Reading....................................................................... 81
TABLAT Register........................................................ 80
Table Pointer............................................................... 80
Boundaries Based on Operation......................... 80
Table Pointer Boundaries ........................................... 80
Table Reads and Table Writes ................................... 77
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 387
PIC18F2331/2431/4331/4431
DCFSNZ ...................................................................309
DECF ........................................................................308
DECFSZ....................................................................309
General Format.........................................................291
GOTO .......................................................................310
INCF..........................................................................310
INCFSZ.....................................................................311
INFSNZ.....................................................................311
IORLW ......................................................................312
IORWF ......................................................................312
LFSR.........................................................................313
MOVF........................................................................313
MOVFF .....................................................................314
MOVLB .....................................................................314
MOVLW ....................................................................315
MOVWF ....................................................................315
MULLW .....................................................................316
MULWF.....................................................................316
NEGF ........................................................................317
NOP ..........................................................................317
POP ..........................................................................318
PUSH ........................................................................318
RCALL ......................................................................319
Read-Modify-Write Operations .................................289
RESET ......................................................................319
RETFIE .....................................................................320
RETLW .....................................................................320
RETURN ...................................................................321
RLCF.........................................................................321
RLNCF ......................................................................322
RRCF ........................................................................322
RRNCF .....................................................................323
SETF.........................................................................323
SLEEP ......................................................................324
SUBFWB...................................................................324
SUBLW .....................................................................325
SUBWF.....................................................................325
SUBWFB...................................................................326
Summary...................................................................289
SWAPF .....................................................................326
TBLRD ......................................................................327
TBLWT......................................................................328
TSTFSZ ....................................................................329
XORLW.....................................................................329
XORWF.....................................................................330
Summary Table.........................................................292
Interrupts............................................................................. 93
Context Saving, During............................................. 108
Interrupts, Enable Bits
CCP1 Enable (CCP1IE Bit) ...................................... 154
Interrupts, Flag Bits
CCP1 Flag (CCP1IF Bit)........................................... 154
CCP1IF Flag (CCP1IF Bit)........................................ 155
CCP2IF Flag (CCP2IF Bit)........................................ 155
Interrupt-on-Change (RB7:RB4)
Flag (RBIF Bit).................................................. 114
INTOSC Frequency Drift..................................................... 44
INTOSC, INTRC. See Internal Oscillator Block.
IORLW.............................................................................. 312
IORWF.............................................................................. 312
IPR Registers.................................................................... 104
2
I C Mode
Operation.................................................................. 219
I C Mode (SSP)
2
Addressing................................................................ 220
Associated Registers................................................ 222
Master Mode............................................................. 222
Mode Selection......................................................... 219
Multi-Master Mode.................................................... 222
Operation.................................................................. 219
Reception ................................................................. 221
Slave Mode............................................................... 219
SCL and SDA Pins ........................................... 219
Transmission ............................................................ 221
L
LFSR................................................................................. 313
Look-up Tables................................................................... 65
Low-Voltage Detect .......................................................... 263
Characteristics.......................................................... 349
Effects of a Reset ..................................................... 267
Operation.................................................................. 266
Current Consumption ....................................... 267
Reference Voltage Set Point ............................ 267
Operation During Sleep ............................................ 267
Low-Voltage ICSP Programming...................................... 288
LVD. See Low-Voltage Detect.......................................... 263
M
Memory Organization ......................................................... 59
Data Memory .............................................................. 65
Program Memory........................................................ 59
Memory Programming Requirements............................... 348
Microchip Internet Web Site.............................................. 393
Migration from Baseline to Enhanced Devices................. 382
Migration from High-End to Enhanced Devices................ 383
Migration from Mid-Range to
Enhanced Devices.................................................... 383
Motion Feedback Module (MFM)...................................... 159
Associated Registers................................................ 179
Summary of Features ............................................... 159
MOVF ............................................................................... 313
MOVFF ............................................................................. 314
MOVLB ............................................................................. 314
MOVLW ............................................................................ 315
MOVWF............................................................................ 315
MPLAB ASM30 Assembler, Linker, Librarian................... 332
MPLAB ICD 2 In-Circuit Debugger ................................... 333
MPLAB ICE 2000 High-Performance
INTCON Register
RBIF Bit.....................................................................114
INTCON Registers ..............................................................95
2
2
Inter-Integrated Circuit (I C). See I C Mode.
Internal Oscillator Block ......................................................26
Adjustment..................................................................26
INTIO Modes...............................................................26
INTRC Output Frequency ...........................................26
OSCTUNE Register....................................................26
Internal RC Oscillator
Use with WDT...........................................................280
Internet Address................................................................393
Interrupt Sources...............................................................269
Capture Complete (CCP)..........................................154
Interrupt-on-Change (RB7:RB4) ...............................114
INTx Pin ....................................................................108
PORTB, Interrupt-on-Change ...................................108
TMR0 ........................................................................108
TMR1 Overflow .........................................................139
TMR2 to PR2 Match (PWM) ............................. 145, 157
Universal In-Circuit Emulator.................................... 333
MPLAB Integrated Development
Environment Software .............................................. 331
DS39616C-page 388
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
MPLAB PM3 Device Programmer .................................... 333
RC6/TX/CK/SS..................................................... 16, 20
RC7/RX/DT/SDO.................................................. 16, 20
RD0/T0CKI/T5CKI...................................................... 21
RD1/SDO.................................................................... 21
RD2/SDI/SDA............................................................. 21
RD3/SCK/SCL............................................................ 21
RD4/FLTA................................................................... 21
RD5/PWM4................................................................. 21
RD6/PWM6................................................................. 21
RD7/PWM7................................................................. 21
RE0/AN6..................................................................... 22
RE1/AN7..................................................................... 22
RE2/AN8..................................................................... 22
VDD ....................................................................... 16, 22
VSS ....................................................................... 16, 22
Pinout I/O Descriptions
PIC18F2331/2431 ...................................................... 14
PIC18F4331/4431 ...................................................... 17
PIR Registers...................................................................... 98
PLL Lock Time-out.............................................................. 48
Pointer, FSRn ..................................................................... 73
POP .................................................................................. 318
POR. See Power-on Reset.
MPLAB REAL ICE In-Circuit Emulator System................. 333
MPLINK Object Linker/MPLIB Object Librarian ................ 332
MULLW ............................................................................. 316
MULWF............................................................................. 316
N
NEGF ................................................................................ 317
NOP .................................................................................. 317
O
Opcode Field Descriptions................................................ 290
Operation in Sleep Mode .................................................. 178
QEI............................................................................ 178
3x Input Capture ....................................................... 178
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 ........................................................... 269
Oscillator Start-up Timer (OST) ............................ 31, 48, 269
Oscillator Switching............................................................. 28
Oscillator Transitions .......................................................... 31
Oscillator, Timer1.............................................................. 139
PORTA
Associated Registers................................................ 113
LATA Register .......................................................... 109
PORTA Register....................................................... 109
TRISA Register......................................................... 109
PORTB
Associated Registers................................................ 119
LATB Register .......................................................... 114
PORTB Register....................................................... 114
RB7:RB4 Interrupt-on-Change Flag
P
(RBIF Bit).......................................................... 114
TRISB Register......................................................... 114
PORTC
Associated Registers................................................ 125
LATC Register.......................................................... 120
PORTC Register....................................................... 120
TRISC Register ........................................................ 120
PORTD
Associated Registers................................................ 130
LATD Register.......................................................... 126
PORTD Register....................................................... 126
TRISD Register ........................................................ 126
PORTE
Associated Registers................................................ 133
LATE Register .......................................................... 131
PORTE Register....................................................... 131
TRISE Register......................................................... 131
Postscaler, WDT
Assignment (PSA Bit)............................................... 137
Rate Select (T0PS2:T0PS0 Bits).............................. 137
Power-Managed Modes...................................................... 33
Comparisons Between Run and Idle Modes .............. 34
Entering ...................................................................... 34
Idle Modes.................................................................. 35
Multiple Sleep Commands.......................................... 34
Run Modes ................................................................. 40
Selecting..................................................................... 33
Sleep Mode ................................................................ 35
Summary (table)......................................................... 33
Wake From................................................................. 42
Power-on Reset (POR)............................................... 48, 269
Power-up Delays ................................................................ 31
P (Stop) Bit........................................................................ 214
Packaging Information ...................................................... 373
Details....................................................................... 375
Marking ..................................................................... 373
Period Measurement Mode............................................... 165
PICSTART Plus Development Programmer ..................... 334
PIE Registers.................................................................... 101
Pin Functions
MCLR/VPP/RE3..................................................... 14, 17
OSC1/CLKI/RA7 ................................................... 14, 17
OSC2/CLKO/RA6 ................................................. 14, 17
RA0/AN0............................................................... 14, 18
RA1/AN1............................................................... 14, 18
RA2/AN2/VREF-/CAP1/INDX................................. 14, 18
RA3/AN3/VREF+/CAP2/QEA................................. 14, 18
RA4/AN4/CAP3/QEB............................................ 14, 18
RA5/AN5/LVDIN ......................................................... 18
RB0/PWM0 ........................................................... 15, 19
RB1/PWM1 ........................................................... 15, 19
RB2/PWM2 ........................................................... 15, 19
RB3/PWM3 ........................................................... 15, 19
RB4/KBIO/PWM5........................................................ 15
RB4/KBI0/PWM5 ........................................................ 19
RB5/KBI1/PWM4/PGM ......................................... 15, 19
RB6/KBI2/PGC ..................................................... 15, 19
RB7/KBI3/PGD ..................................................... 15, 19
RC0/T1OSO/T1CKI .............................................. 16, 20
RC1/T1OSI/CCP2/FLTA....................................... 16, 20
RC2/CCP1/FLTB .................................................. 16, 20
RC3/T0CKI/T5CKI/INT0........................................ 16, 20
RC4/INT1/SDI/SDA............................................... 16, 20
RC5/INT2/SCK/SCL.............................................. 16, 20
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 389
PIC18F2331/2431/4331/4431
Power-up Timer (PWRT).......................................31, 48, 269
Prescaler, Timer0..............................................................137
Q
Q Clock............................................................................. 158
QEI
Assignment (PSA Bit) ...............................................137
Rate Select (T0PS2:T0PS0 Bits) ..............................137
Prescaler, Timer2..............................................................158
Program Counter
PCL Register...............................................................62
PCLATH Register .......................................................62
PCLATU Register .......................................................62
Program Memory
and IC Shared Interrupts .......................................... 178
Configuration ............................................................ 170
Direction of Rotation ................................................. 171
Interrupts .................................................................. 172
Sampling Modes....................................................... 171
Velocity Measurement .............................................. 175
Quadrature Encoder Interface (QEI)................................. 169
Instructions..................................................................64
Two-Word ...........................................................64
Interrupt Vector ...........................................................59
Map and Stack
R
R/W Bit.............................................................. 214, 220, 221
RAM. See Data Memory.
PIC18F2331/4331...............................................59
PIC18F2431/4431...............................................59
Reset Vector ...............................................................59
Program Verification..........................................................285
Pulse-Width Measurement Mode......................................165
Pulse-Width Modulation. See PWM (CCP Module).
PUSH ................................................................................318
PUSH and POP Instructions ...............................................61
PWM
RC Oscillator....................................................................... 25
RCIO Oscillator Mode................................................. 25
RCALL .............................................................................. 319
RCON Register
Bit Status During Initialization..................................... 49
Bits and Positions ....................................................... 49
RCSTA Register
SPEN Bit................................................................... 223
Reader Response............................................................. 394
Registers
Associated Registers ................................................211
Complementary Operation........................................198
Control Registers ......................................................184
Dead-Time Generators .............................................199
Fault Inputs ...............................................................207
Functionality..............................................................184
Modes
ADCHS (A/D Channel Select) .................................. 250
ADCON0 (A/D Control 0).......................................... 246
ADCON1 (A/D Control 1).......................................... 247
ADCON2 (A/D Control 2).......................................... 248
ADCON3 (A/D Control 3).......................................... 249
ANSEL0 (Analog Select 0) ....................................... 251
ANSEL1 (Analog Select 1) ....................................... 251
BAUDCTL (Baud Rate Control)................................ 226
CAPxCON (Input Capture x Control)........................ 163
CCPxCON (CCPx Control)....................................... 153
CONFIG1H (Configuration 1 High)........................... 270
CONFIG2H (Configuration 2 High)........................... 272
CONFIG2L (Configuration 2 Low) ............................ 271
CONFIG3H (Configuration 3 High)........................... 274
CONFIG3L (Configuration 3 Low) ............................ 273
CONFIG4L (Configuration 4 Low) ............................ 275
CONFIG5H (Configuration 5 High)........................... 276
CONFIG5L (Configuration 5 Low) ............................ 276
CONFIG6H (Configuration 6 High)........................... 277
CONFIG6L (Configuration 6 Low) ............................ 277
CONFIG7H (Configuration 7 High)........................... 278
CONFIG7L (Configuration 7 Low) ............................ 278
DEVID1 (Device ID 1)............................................... 279
DEVID2 (Device ID 2)............................................... 279
DFLTCON (Digital Filter Control).............................. 177
DTCON (Dead-Time Control) ................................... 200
EECON1 (Flash Program/Data
EEPROM Control 1) ..................................... 79, 88
FLTCONFIG (Fault Configuration)............................ 209
INTCON (Interrupt Control)......................................... 95
INTCON2 (Interrupt Control 2).................................... 96
INTCON3 (Interrupt Control 3).................................... 97
IPR1 (Peripheral Interrupt Priority 1) ........................ 104
IPR2 (Peripheral Interrupt Priority 2) ........................ 105
IPR3 (Peripheral Interrupt Priority 3) ........................ 106
LVDCON (Low-Voltage Detect Control) ................... 265
OSCCON (Oscillator Control)..................................... 30
OSCTUNE (Oscillator Tuning).................................... 27
OVDCOND (Output Override Control)...................... 204
Continuous Up/Down Count .............................188
Free-Running....................................................188
Single-Shot .......................................................188
Output and Polarity Control.......................................206
Output Override ........................................................202
Single-Pulse Operation .............................................202
Special Event Trigger................................................210
Time Base.................................................................184
Update Lockout.........................................................210
PWM (CCP Module)
Associated Registers ................................................158
CCPR1H:CCPR1L Registers....................................157
Duty Cycle.................................................................157
Example Frequencies/Resolutions ...........................158
Period........................................................................157
PR2 Register, Writing ...............................................157
Setup for PWM Operation.........................................158
TMR2 to PR2 Match .........................................145, 157
PWM Duty Cycle...............................................................195
Center-Aligned ..........................................................197
Comparison...............................................................195
Edge-Aligned ............................................................196
Register Buffers ........................................................196
Registers...................................................................195
PWM Period......................................................................193
PWM Time Base
Interrupts...................................................................189
Continuous Up/Down Count Mode ...................190
Double Update Mode........................................192
Free-Running Mode..........................................189
Single-Shot Mode .............................................190
Postscaler .................................................................189
Prescaler...................................................................188
DS39616C-page 390
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
OVDCONS (Output State) ........................................ 204
SPI Mode (SSP) ............................................................... 213
Associated Registers................................................ 218
Serial Clock .............................................................. 213
Serial Data In............................................................ 213
Serial Data Out......................................................... 213
Slave Select.............................................................. 213
SS..................................................................................... 213
SSP
PIE1 (Peripheral Interrupt Enable 1)......................... 101
PIE2 (Peripheral Interrupt Enable 2)......................... 102
PIE3 (Peripheral Interrupt Enable 3)......................... 103
PIR1 (Peripheral Interrupt Request
(Flag) 1) .............................................................. 98
PIR2 (Peripheral Interrupt Request
(Flag) 2) .............................................................. 99
PIR3 (Peripheral Interrupt Request
Overview.
(Flag) 3) ............................................................ 100
PTCON0 (PWM Timer Control 0) ............................. 186
PTCON1 (PWM Timer Control 1) ............................. 186
PWMCON0 (PWM Control 0) ................................... 187
PWMCON1 (PWM Control 1) ................................... 188
QEICON (QEI Control).............................................. 170
RCON (Reset Control)........................................ 76, 107
RCSTA (Receive Status and Control)....................... 225
SSPCON (SSP Control)............................................ 215
SSPSTAT (SSP Status)............................................ 214
STATUS...................................................................... 75
STKPTR (Stack Pointer)............................................. 61
Summary............................................................... 68–71
TRISE ....................................................................... 133
TXSTA (Transmit Status and Control) ...................... 224
T0CON (Timer0 Control)........................................... 135
T1CON (Timer1 Control)........................................... 139
T2CON (Timer2 Control)........................................... 145
T5CON (Timer5 Control)........................................... 147
WDTCON (Watchdog Timer Control) ....................... 281
RESET .............................................................................. 319
Reset................................................................................... 47
Resets............................................................................... 269
RETFIE ............................................................................. 320
RETLW ............................................................................. 320
RETURN ........................................................................... 321
Return Address Stack......................................................... 60
Return Stack Pointer (STKPTR) ......................................... 60
Revision History................................................................ 381
RLCF................................................................................. 321
RLNCF .............................................................................. 322
RRCF ................................................................................ 322
RRNCF ............................................................................. 323
TMR2 Output for Clock Shift............................. 145, 146
SSPEN Bit ........................................................................ 215
SSPM<3:0> Bits ............................................................... 215
SSPOV Bit ........................................................................ 215
Stack Full/Underflow Resets............................................... 61
SUBFWB .......................................................................... 324
SUBLW............................................................................. 325
SUBWF............................................................................. 325
SUBWFB .......................................................................... 326
SWAPF............................................................................. 326
Synchronous Serial Port. See SSP
T
TABLAT Register................................................................ 80
Table Pointer Operations (table)......................................... 80
Table Reads/Table Writes.................................................. 65
TBLPTR Register................................................................ 80
TBLRD.............................................................................. 327
TBLWT ............................................................................. 328
Time-out in Various Situations (table)................................. 49
Time-out Sequence ............................................................ 49
Timer0 .............................................................................. 135
Associated Registers................................................ 137
Clock Source Edge Select (T0SE Bit) ...................... 137
Clock Source Select (T0CS Bit) ............................... 137
Interrupt .................................................................... 137
Operation.................................................................. 137
Prescaler .................................................................. 137
Switching Assignment ...................................... 137
Prescaler. See Prescaler, Timer0.
16-Bit Mode Timer Reads and Writes ...................... 137
Timer1 .............................................................................. 139
Associated Registers................................................ 143
Interrupt .................................................................... 142
Operation.................................................................. 140
Oscillator........................................................... 139, 141
Layout Considerations...................................... 141
Overflow Interrupt..................................................... 139
Resetting, Using a Special Event Trigger
Output (CCP).................................................... 142
Special Event Trigger (CCP) .................................... 155
TMR1H Register....................................................... 139
TMR1L Register ....................................................... 139
Use as a Real-Time Clock (RTC)............................. 142
16-Bit Read/Write Mode ........................................... 142
Timer2 .............................................................................. 145
Associated Registers................................................ 146
Interrupt .................................................................... 146
Operation.................................................................. 145
Postscaler. See Postscaler, Timer2.
S
S (Start) Bit ....................................................................... 214
SCK................................................................................... 213
SCL ................................................................................... 219
SDI.................................................................................... 213
SDO .................................................................................. 213
Serial Clock (SCK) Pin...................................................... 213
Serial Data In (SDI) Pin..................................................... 213
Serial Data Out (SDO) Pin ................................................ 213
SETF................................................................................. 323
Slave Select (SS) Pin........................................................ 213
SLEEP .............................................................................. 324
Sleep
OSC1 and OSC2 Pin States....................................... 31
Software Simulator (MPLAB SIM)..................................... 332
Special Event Trigger (CAP1 Only) .................................. 168
Special Event Trigger. See Compare (CCP Module).
Special Features of the CPU ............................................ 269
Special Function Registers
Prescaler. See Prescaler, Timer2.
PR2 Register ............................................................ 145
SSP Clock Shift ................................................ 145, 146
TMR2 Register ......................................................... 145
TMR2 to PR2 Match Interrupt........................... 145, 157
Map............................................................................. 67
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 391
PIC18F2331/2431/4331/4431
Timer5...............................................................................147
Associated Registers ................................................151
Interrupt.....................................................................150
Noise Filter................................................................150
Operation ..................................................................148
Continuous Count and Single-Shot...................149
Sleep Mode.......................................................150
Prescaler...................................................................149
Special Event Trigger Output....................................150
Special Event Trigger Reset Input ............................150
16-Bit Read/Write and Write Modes .........................149
16-Bit Read-Modify-Write..........................................149
Timing Diagrams
PWM Time Base Interrupt, Continuous
Up/Down Count Mode with Double Updates.... 192
PWM Time Base Interrupt,
Free-Running Mode.......................................... 189
PWM Time Base Interrupt, Single-Shot Mode.......... 190
QEI Inputs When Sampled by Filter ......................... 173
QEI Reset on Period Match...................................... 173
QEI Reset with the Index Input................................. 174
Reset, Watchdog Timer (WDT), Oscillator Start-up
Timer (OST), Power-up Timer (PWRT)............ 357
Send Break Character Sequence............................. 238
Slow Rise Time (MCLR Tied to VDD,
VDD Rise > TPWRT)............................................. 57
SPI Mode (Master Mode).......................................... 217
SPI Mode (Slave Mode with CKE = 0)...................... 217
SPI Mode (Slave Mode with CKE = 1)...................... 218
Asynchronous Reception ..........................................236
Asynchronous Transmission.....................................233
Asynchronous Transmission
(Back to Back)...................................................233
Automatic Baud Rate Calculation .............................231
Auto-Wake-up Bit (WUE) During
Normal Operation..............................................237
Auto-Wake-up Bit (WUE) During Sleep ....................237
Brown-out Reset (BOR)............................................357
Capture/Compare/PWM (All CCP Modules).............359
CAPx Interrupts and IC1
Special Event Trigger........................................167
CLKO and I/O ...........................................................356
Clock, Instruction Cycle ..............................................63
Dead-Time Insertion for
2
SSP I C Bus Data .................................................... 366
2
SSP I C Bus Start/Stop Bits ..................................... 366
Start of Center-Aligned PWM ................................... 197
Synchronous Reception
(Master Mode, SREN) ...................................... 241
Synchronous Transmission ...................................... 239
Synchronous Transmission (Through TXEN)........... 240
Time-out Sequence on POR w/PLL Enabled
(MCLR Tied to VDD) ........................................... 57
Time-out Sequence on Power-up
(MCLR Not Tied to VDD): Case 1 ....................... 56
Time-out Sequence on Power-up
Complementary PWM.......................................199
Duty Cycle Update Times in Continuous
(MCLR Not Tied to VDD): Case 2 ....................... 56
Time-out Sequence on Power-up
Up/Down Count Mode.......................................196
Duty Cycle Update Times in Continuous Up/Down
Count Mode with Double Updates ....................197
Edge Capture Mode..................................................164
Edge-Aligned PWM...................................................196
EUSART Synchronous Receive
(MCLR Tied to VDD, VDD Rise TPWRT)............... 56
Timer0 and Timer1 External Clock ........................... 358
Transition for Entry to SEC_IDLE Mode..................... 38
Transition for Entry to SEC_RUN Mode ..................... 40
Transition for Entry to Sleep Mode ............................. 36
Transition for Two-Speed Start-up
(Master/Slave)...................................................368
EUSART SynchronousTransmission
(INTOSC to HSPLL) ......................................... 282
Transition for Wake From PRI_IDLE Mode ................ 37
Transition for Wake From RC_RUN Mode
(RC_RUN to PRI_RUN) ..................................... 39
Transition for Wake From SEC_RUN
(Master/Slave)...................................................368
Example SPI Master Mode (CKE = 0) ......................360
Example SPI Master Mode (CKE = 1) ......................361
Example SPI Slave Mode (CKE = 0) ........................362
Example SPI Slave Mode (CKE = 1) ........................363
External Clock (All Modes Except PLL) ....................354
Fail-Safe Clock Monitor.............................................284
Input Capture on State Change ................................166
Mode (HSPLL).................................................... 38
Transition for Wake From Sleep (HSPLL) .................. 36
Transition to PRI_IDLE Mode..................................... 37
Transition to RC_IDLE Mode...................................... 39
Transition to RC_RUN Mode...................................... 41
Velocity Measurement .............................................. 176
Timing Diagrams and Specifications ................................ 354
Capture/Compare/PWM Requirements
2
I C Bus Data.............................................................364
2
I C Bus Start/Stop Bits..............................................364
2
I C Reception (7-bit Address)...................................221
2
I C Transmission (7-bit Address)..............................221
(All CCP Modules)............................................ 359
CLKO and I/O Requirements.................................... 356
EUSART Synchronous Receive
Requirements ................................................... 368
EUSART Synchronous Transmission
Requirements ................................................... 368
Example SPI Mode Requirements
(Master Mode, CKE = 0)................................... 360
Example SPI Mode Requirements
(Master Mode, CKE = 1)................................... 361
Example SPI Mode Requirements
(Slave Mode, CKE = 0)..................................... 362
Example SPI Slave Mode Requirements
(CKE = 1).......................................................... 363
External Clock Requirements ................................... 354
Low-Voltage Detect...................................................266
Low-Voltage Detect Characteristics..........................349
Noise Filter................................................................178
Pulse-Width Measurement Mode..............................165
PWM Output .............................................................157
PWM Output Override (Example 1) ..........................205
PWM Output Override (Example 2) ..........................205
PWM Override Bits in Complementary Mode ...........203
PWM Period Buffer Updates in Continuous
Up/Down Count Mode.......................................194
PWM Period Buffer Updates in
Free-Running Mode..........................................194
PWM Time Base Interrupt, Continuous
Up/Down Count Mode.......................................191
DS39616C-page 392
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
Internal RC Accuracy................................................ 355
I C Bus Data Requirements (Slave Mode) ............... 365
U
2
UA Bit ............................................................................... 214
USART
PLL Clock.................................................................. 355
Reset, Watchdog Timer, Oscillator Start-up
Timer, Power-up Timer and Brown-out
Synchronous Slave Mode
Transmission .................................................... 242
Reset Requirements......................................... 357
2
SSP I C Bus Data Requirements ............................. 367
W
2
SSP I C Bus Start/Stop Bits Requirements.............. 366
Watchdog Timer (WDT)............................................ 269, 280
Associated Registers................................................ 281
Control Register........................................................ 280
During Oscillator Failure........................................... 283
Programming Considerations................................... 280
WWW Address ................................................................. 393
WWW, On-Line Support ....................................................... 7
Timer0 and Timer1 External Clock
Requirements ................................................... 358
Top-of-Stack Access........................................................... 60
TSTFSZ ............................................................................ 329
Two-Speed Start-up.................................................. 269, 282
Two-Word Instructions
Example Cases........................................................... 64
TXSTA Register
X
BRGH Bit .................................................................. 227
T0CON Register
XORLW ............................................................................ 329
XORWF ............................................................................ 330
PSA Bit...................................................................... 137
T0CS Bit.................................................................... 137
T0PS2:T0PS0 Bits.................................................... 137
T0SE Bit.................................................................... 137
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 393
PIC18F2331/2431/4331/4431
NOTES:
DS39616C-page 394
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
THE MICROCHIP WEB SITE
CUSTOMER SUPPORT
Microchip provides online support via our WWW site at
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Technical support is available through the web site
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To register, access the Microchip web site at
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© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 395
PIC18F2331/2431/4331/4431
READER RESPONSE
It is our intention to provide you with the best documentation possible to ensure successful use of your Microchip prod-
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DS39616C
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PIC18F2331/2431/4331/4431
Device:
Questions:
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DS39616C-page 396
Preliminary
© 2007 Microchip Technology Inc.
PIC18F2331/2431/4331/4431
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) PIC18LF4431-I/P 301 = Industrial temp.,
PDIP package, Extended VDD limits,
QTP pattern #301.
b) PIC18LF2331-I/SO = Industrial temp.,
SOIC package, Extended VDD limits.
c) PIC18F4331-I/P = Industrial temp., PDIP
package, normal VDD limits.
(1)
Device
PIC18F2331/2431/4331/4431
,
(1,2)
PIC18F2331/2431/4331/4431T
;
VDD range 4.2V to 5.5V
(1)
PIC18LF2331/2431/4331/4431
,
(1,2)
PIC18LF2331/2431/4331/44310T
;
VDD range 2.0V to 5.5V
Temperature
Range
I
=
-40°C to +85°C (Industrial)
Note 1: F = Standard Voltage range
LF = Wide Voltage Range
Package
PT = TQFP (Thin Quad Flatpack)
SO = SOIC
2: T = in tape and reel - SOIC
and TQFP packages only.
SP = Skinny Plastic DIP
P
= PDIP
ML = QFN
Pattern
QTP, SQTP, Code or Special Requirements
(blank otherwise)
© 2007 Microchip Technology Inc.
Preliminary
DS39616C-page 397
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06/25/07
DS39616C-page 398
Preliminary
© 2007 Microchip Technology Inc.
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