C501G-1R [INFINEON]
8-Bit Single-Chip Microcontroller; 8位单芯片微控制器
| 型号： | C501G-1R |
| 厂家： | 
Infineon |
| 描述： | 8-Bit Single-Chip Microcontroller |
| 文件： | 总121页 (文件大小：1045K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
C501
8-Bit Single-Chip Microcontroller
User’s Manual 04.97
Edition 04.97
This edition was realized using the software
system FrameMaker .
Published by Siemens AG,
Bereich Halbleiter, Marketing-
Kommunikation, Balanstraße 73,
81541 München
©
Siemens AG 1997.
All Rights Reserved.
Attention please!
As far as patents or other rights of third par-
ties are concerned, liability is only assumed
for components, not for applications, pro-
cesses and circuits implemented within com-
ponents or assemblies.
The information describes the type of compo-
nent and shall not be considered as assured
characteristics.
Terms of delivery and rights to change design
reserved.
For questions on technology, delivery and
prices please contact the Semiconductor
Group Offices in Germany or the Siemens
Companies and Representatives worldwide
(see address list).
Due to technical requirements components
may contain dangerous substances. For in-
formation on the types in question please
contact your nearest Siemens Office, Semi-
conductor Group.
Siemens AG is an approved CECC manufac-
turer.
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Components used in life-support devices
or systems must be expressly authorized
for such purpose!
1
Critical components of the Semiconductor
Group of Siemens AG, may only be used in
2
life-support devices or systems with the ex-
press written approval of the Semiconductor
Group of Siemens AG.
1
A critical component is a component used
in a life-support device or system whose
failure can reasonably be expected to
cause the failure of that life-support de-
vice or system, or to affect its safety or ef-
fectiveness of that device or system.
2
Life support devices or systems are in-
tended (a) to be implanted in the human
body, or (b) to support and/or maintain
and sustain human life. If they fail, it is
reasonable to assume that the health of
the user may be endangered.
C501 User’s Manual
Revision History :
04.97
Previous Releases :
02.96, 08.94, 08.93 (Original Version)
Subjects (changes since last revision)
Page
Page
(previous (new
version)
general
version)
C501G-1E OTP version included (new chapter 9, AC/DC characteristics
now in chapter 10)
Chapter 1 Chapter 1 Several figures: update with C501-1E signal names and definitions;
P-MQFP-44 package (pin configuration and pin numbers) added
1-2
1-2
Feature list is updated
3-4 to 3-6 3-2 to 3-7 Actualized design of the SFR tables
4-2
-
6-10
4-4
4-5
6-10
Figure 4-1 moved
Description of enhanced hooks emulation concept added
Figure 6-6 corrected
6-15 follo. 6-15, 6-16 Improved timer 0/1 register description
6-23 follo. 6-22, 6-23 Improved timer 2 register description
6-30 follo. 6-29
Improved serial port register description
chapter 7 chapter 7 Improved description of the interrupt related functions: all enable,
control, and request register bits now included
8-2
-
8-4
Table 8-1 moved into chapter 8.4
chapter 9 New chapter 9 “OTP Memory Operation of the C501-1E” included
chapter 9 chapter 10 Old chapter 9 (“Device Specifications”) is now chapter 10
-
10-3
“DC Characteristics for C501-1E” included
9-6, 9-9
10-6,10-8 Characteristics for “External Clock Drive” on three pages moved below
9-12
10-10
“Ext. Data Memory Characteristics”
9-17
10-13
Old figure 7 moved to figure 10-4
-
10-15/16
10-18
10-21
New chapter 10.8 “OTP Programming and Verification Characteristics”
Figure 10-9: M-QFP-44 pin numbers for XTAL1/XTAL2 added
M-QFP-44 package outline added
9-18
-
-
chapter 11 Manual index information added
C501
Table of Contents
Page
1
1.1
1.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Pin Definitions and Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
2
2.1
2.2
Fundamental Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
CPU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
CPU Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
3
Memory Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Program Memory, “Code Space” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Data Memory, “Data Space” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
General Purpose Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Special Function Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.1
3.2
3.3
3.4
4
4.1
4.1.1
4.1.2
4.1.3
4.2
4.3
4.4
4.5
External Bus Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Accessing External Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Role of P0 and P2 as Data/Address Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
External Program Memory Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
PSEN, Program Store Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
ALE, Address Latch Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Overlapping External Data and Program Memory Spaces . . . . . . . . . . . . . 4-4
Enhanced Hooks Emulation Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
5
5.1
5.2
System Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Hardware Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Hardware Reset Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
6
6.1
6.1.1
On-Chip Peripheral Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Parallel I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Port Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.1.1.1 Port 0 and Port 2 used as Address/Data Bus . . . . . . . . . . . . . . . . . . . . . . . 6-7
6.1.2
6.1.3
Alternate Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
Port Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10
6.1.3.1 Port Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10
6.1.3.2 Port Loading and Interfacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11
6.1.3.3 Read-Modify-Write Feature of Ports 1,2 and 3 . . . . . . . . . . . . . . . . . . . . . 6-11
6.2
6.2.1
Timers/Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13
Timer/Counter 0 and 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14
6.2.1.1 Timer/Counter 0 and 1 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-15
6.2.1.2 Mode 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-18
6.2.1.3 Mode 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-19
6.2.1.4 Mode 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20
6.2.1.5 Mode 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21
Semiconductor Group
I-1
C501
Table of Contents
Page
6.2.2
Timer/Counter 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22
6.2.2.1 Timer 2 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23
6.2.2.2 Auto-Reload (Up or Down Counter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26
6.2.2.3 Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28
6.3
Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29
Multiprocessor Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-30
Serial Port Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-30
Baud Rates Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-32
6.3.1
6.3.2
6.3.3
6.3.3.1 Using Timer 1 to Generate Baud Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33
6.3.3.2 Using Timer 2 to Generate Baud Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34
6.3.4
6.3.5
6.3.6
Details about Mode 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-36
Details about Mode 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-39
Details about Modes 2 and 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-42
7
7.1
7.1.1
7.1.2
7.1.3
7.2
7.3
7.4
7.5
Interrupt System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Interrupt Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
Interrupt Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
Interrupt Request / Control Flags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
Interrupt Priority Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6
Interrupt Priority Level Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7
How Interrupts are Handled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8
External Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10
Interrupt Response Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11
8
Power Saving Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
Power Saving Mode Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
Idle Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
Power Down Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
State of Pins in Software Initiated Power Saving Modes . . . . . . . . . . . . . . . 8-4
8.1
8.2
8.3
8.4
9
OTP Memory Operation of the C501-1E . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
Programming Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
Quick-Pulse Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2
Encryption Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
Security Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
OTP Memory Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4
9.1
9.2
9.3
9.4
9.5
Semiconductor Group
I-2
C501
Table of Contents
Page
10
Device Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
DC Characteristics for C501-L / C501-1R . . . . . . . . . . . . . . . . . . . . . . . . . 10-2
DC Characteristics for C501-1E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3
AC Characteristics for C501-L / C501-1R / C501-1E . . . . . . . . . . . . . . . . 10-5
AC Characteristics for C501-L24 / C501-1R24 / C501-1E24 . . . . . . . . . . . 10-7
AC Characteristics for C501-L40 / C501-1R40 . . . . . . . . . . . . . . . . . . . . . 10-9
ROM Verification Characteristics for C501-1R . . . . . . . . . . . . . . . . . . . . . 10-14
OTP Programming and Verification Characteristics for C501-1E . . . . . . 10-15
Package Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-19
10.1
10.2
10.3
10.4
10.5
10.6
10.7
10.8
10.9
11
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-1
Semiconductor Group
I-3
Introduction
C501
1
Introduction
The C501-L, C501-1R, and C501-1E described in this document are compatible (also pin-
compatible) with the 80C52 and can be used in typical 80C52 applications.
The C501-1R contains a non-volatile 8K×8 read-only program memory, a volatile 256×8 read/write
data memory, four ports, three 16-bit timers/counters, a seven source, two priority level interrupt
structure and a serial port. The C501-L is identical, except that it lacks the program memory on
chip. The C501-1E contains a one-time programmable (OTP) program memory on chip. The term
C501 refers to all versions within this specification unless otherwise noted.
Power
RAM
Port 0
Port 1
Port 2
Port 3
Ι
Ι
Ι
Ι
/O
/O
/O
/O
Saving
Modes
256 x 8
T0
T1
USART
T2
CPU
8K x 8 ROM (C501-1R)
8K x 8 OTP (C501-1E)
MCA03238
Figure 1-1
C501G Functional Units
Semiconductor Group
1-1
Introduction
C501
Listed below is a summary of the main features of the C501:
• Fully compatible to standard 8051 microcontroller
• Versions for 12/24/40 MHz operating frequency
• Program memory : completely external (C501-L)
8K × 8 ROM (C501-1R)
8K × 8 OTP memory (C501-1E)
• 256 × 8 RAM
• Four 8-bit ports
• Three 16-bit timers / counters (timer 2 with up/down counter feature)
• USART
• Six interrupt sources, two priority levels
• Power saving modes
• Quick Pulse programming algorithm (C501-1E only)
• 2-Level program memory lock (C501-1E only)
• P-DIP-40, P-LCC-44, and P-MQFP-44 package
• Temperature ranges :
SAB-C501
SAF-C501
TA : 0 ˚C to 70 ˚C
TA : – 40 ˚C to 85 ˚C
VCC
VSS
Port 0
8-Bit Digital Ι /O
XTAL1
XTAL2
Port 1
8-Bit Digital Ι /O
RESET
C501
Port 2
8-Bit Digital Ι /O
EA/
VPP
ALE/PROG
PSEN
Port 3
8-Bit Digital Ι /O
MCL03217
Figure 1-2
Logic Symbol
Semiconductor Group
1-2
Introduction
C501
1.1
Pin Configuration
This section shows the pin configuration of the C501 in the P-LCC-44, P-DIP-40, and P-MQFP-44
packages.
V
6
5
4
3
2
1 44 43 42 41 40
P1.5
P1.6
7
8
39
38
37
36
35
34
33
32
31
30
29
P0.4/AD4
P0.5/AD5
P0.6/AD6
P0.7/AD7
EA/VPP
P1.7
9
RESET
RxD/P3.0
N.C.
10
11
12
13
14
15
16
17
C501
N.C.
TxD/P3.1
INT0/P3.2
INT1/P3.3
T0/P3.4
T1/P3.5
ALE/PROG
PSEN
P2.7/A15
P2.6/A14
P2.5/A13
18 19 20 21 22 23 24 25 26 27 28
MCP03214
V
Figure 1-3
Pin Configuration P-LCC-44 Package (top view)
Semiconductor Group
1-3
Introduction
C501
T2/P1.0
T2EX/P1.1
P1.2
1
40
39
VCC
2
P0.0/AD0
P0.1/AD1
P0.2/AD2
P0.3/AD3
P0.4/AD4
P0.5/AD5
P0.6/AD6
P0.7/AD7
EA/VPP
3
38
P1.3
4
37
P1.4
5
36
P1.5
6
35
P1.6
7
34
P1.7
8
33
RESET
RxD/P3.0
TxD/P3.1
INT0/P3.2
9
32
10
11
12
13
14
15
16
17
18
19
20
31
C501
30
ALE/PROG
PSEN
29
28
P2.7/A15
P2.6/A14
P2.5/A13
P2.4/A12
P2.3/A11
P2.2/A10
P2.1/A9
INT1/P3.3
T0/P3.4
T1/P3.5
WR/P3.6
RD/P3.7
XTAL2
27
26
25
24
23
XTAL1
22
21
P2.0/A8
VSS
MCP03215
Figure 1-4
Pin Configuration P-DIP-40 Package (top view)
Semiconductor Group
1-4
Introduction
C501
V
33 32 31 30 29 28 27 26 25 24 23
P0.3/AD3
P0.2/AD2
P0.1/AD1
P0.0/AD0
VCC
N.C.
P1.0/T2
P1.1/T2EX
P1.2
34
35
36
37
38
39
40
41
42
43
44
22
21
20
19
18
17
16
15
14
13
12
P2.4/A12
P2.3/A11
P2.2/A10
P2.1/A9
P2.0/A8
N.C.
VSS
XTAL1
XTAL2
RD/P3.7
WR/P3.6
C501
P1.3
P1.4
1
2
3
4
5
6
7
8
9 10 11
MCP03216
Figure 1-5
Pin Configuration P-MQFP-44 Package (top view)
Semiconductor Group
1-5
Introduction
C501
1.2 Pin Definitions and Functions
This section describes all external signals of the C501 with its function.
Table 1-1
Pin Definitions and Functions
Symbol
Pin Number
I/O*) Function
P-LCC-44 P-DIP-40 P-MQFP-44
P1.0 – P1.7 2–9
1–8
40–44,
1–3,
I/O
Port 1
is a quasi-bidirectional I/O port with
internal pull-up resistors. Port 1 pins that
have 1s written to them are pulled high by
the internal pullup resistors, and in that
state can be used as inputs. As inputs,
port 1 pins being externally pulled low will
source current (IIL, in the DC character-
istics) because of the internal pull-up
resistors. Port 1 also contains the timer 2
pins as secondary function. The output
latch corresponding to a secondary
function must be pro-grammed to a one
(1) for that function to operate.
The secondary functions are assigned to
the pins of port 1, as follows:
2
3
1
2
40
41
P1.0 T2
Input to counter 2
P1.1 T2EX Capture - Reload trigger of
timer 2 / Up-Down count
*) I = Input
O = Output
Semiconductor Group
1-6
Introduction
C501
Table 1-1
Pin Definitions and Functions (cont’d)
Symbol
Pin Number
I/O*) Function
P-LCC-44 P-DIP-40 P-MQFP-44
P3.0 – P3.7 11,
13–19
10–17
5, 7–13
I/O
Port 3
is a quasi-bidirectional I/O port with
internal pull-up resistors. Port 3 pins that
have 1s written to them are pulled high by
the internal pull-up resistors, and in that
state they can be used as inputs. As
inputs, port 3 pins being externally pulled
low will source current (IIL, in the DC
characteristics) because of the internal
pull-up resistors. Port 3 also contains the
interrupt, timer, serial port 0 and external
memory strobe pins which are used by
various options. The output latch
corresponding to a secondary function
must be programmed to a one (1) for that
function to operate.
The secondary functions are assigned to
the pins of port 3, as follows:
11
13
10
11
5
7
P3.0 R×D receiver data input (asyn-
chronous) or data input
output (synchronous) of
serial interface 0
P3.1 T×D transmitter data output
(asynchronous) or clock
output (synchronous) of
the serial interface 0
14
15
12
13
8
9
P3.2 INT0 interrupt 0 input/timer 0
gate control
P3.3 INT1 interrupt 1 input/timer 1
gate control
16
17
18
14
15
16
10
11
12
P3.4 T0
P3.5 T1
P3.6 WR
counter 0 input
counter 1 input
the write control signal lat-
ches the data byte from
port 0 into the external
data memory
19
17
13
P3.7 RD
the read control signal
enables the external data
memory to port 0
*) I = Input
O = Output
Semiconductor Group
1-7
Introduction
C501
Table 1-1
Pin Definitions and Functions (cont’d)
Symbol
Pin Number
I/O*) Function
P-LCC-44 P-DIP-40 P-MQFP-44
XTAL2
20
18
14
–
–
XTAL2
Output of the inverting oscillator
amplifier.
XTAL1
21
19
15
XTAL1
Input to the inverting oscillator amplifier
and input to the internal clock generator
circuits.
To drive the device from an external
clock source, XTAL1 should be driven,
while XTAL2 is left unconnected. There
are no requirements on the duty cycle of
the external clock signal, since the input
to the internal clocking circuitry is divided
down by a divide-by-two flip-flop.
Minimum and maximum high and low
times as well as rise fall times specified
in the AC characteristics must be
observed.
P2.0 – P2.7 24–31
21–28
18–25
I/O
Port 2
is a quasi-bidirectional I/O port with
internal pull-up resistors. Port 2 pins that
have 1s written to them are pulled high
by the internal pull-up resistors, and in
that state they can be used as inputs. As
inputs, port 2 pins being externally pulled
low will source current (IIL, in the DC
characteristics) because of the internal
pull-up resistors. Port 2 emits the high-
order address byte during fetches from
external program memory and during
accesses to external data memory that
use 16-bit addresses (MOVX @DPTR).
In this application it uses strong internal
pull-up resistors when issuing 1s. During
accesses to external data memory that
use 8-bit addresses (MOVX @Ri),
port 2 issues the contents of the P2
special function register.
*) I = Input
O = Output
Semiconductor Group
1-8
Introduction
C501
Table 1-1
Pin Definitions and Functions (cont’d)
Symbol
Pin Number
I/O*) Function
P-LCC-44 P-DIP-40 P-MQFP-44
PSEN
32
29
26
O
The Program Store Enable
output is a control signal that enables the
external program memory to the bus
during external fetch operations. It is
activated every six oscillator periods
except during external data memory
accesses. Remains high during internal
program execution.
RESET
10
9
4
I
RESET
A high level on this pin for two machine
cycles while the oscillator is running
resets the device. An internal diffused
resistor to VSS permits power-on reset
using only an external capacitor to VCC.
ALE/PROG 33
30
27
I/O
The Address Latch Enable
output is used for latching the low-byte of
the address into external memory during
normal operation. It is activated every six
oscillator periods except during an
external data memory access.
For the C501-1E this pin is also the
program pulse input (PROG) during OTP
memory programming.
EA/VPP
35
31
29
I
External Access Enable
When held at high level, instructions are
fetched from the internal ROM (C501-1R
and C501-1E) when the PC is less than
2000 . When held at low level, the C501
H
fetches all instructions from external
program memory. For the C501-L this
pin must be tied low.
This pin also receives the programming
supply voltage VPP during OTP memory
programming (C501-1E) only).
*) I = Input
O = Output
Semiconductor Group
1-9
Introduction
C501
Table 1-1
Pin Definitions and Functions (cont’d)
Symbol
Pin Number
I/O*) Function
P-LCC-44 P-DIP-40 P-MQFP-44
P0.0 – P0.7 43–36
39–32
37–30
I/O
Port 0
is an 8-bit open-drain bidirectional I/O
port. Port 0 pins that have 1s written to
them float, and in that state can be used
as high-impedance inputs. Port 0 is also
the multiplexed low-order address and
data bus during accesses to external
program or data memory. In this
application it uses strong internal pull-up
resistors when issuing 1s.
Port 0 also outputs the code bytes during
program verification in the C501-1R and
C501-1E. External pull-up resistors are
required during program verification.
VSS
22
44
20
40
–
16
38
–
–
–
Circuit ground potential
Supply terminal for all operating modes
No connection
VCC
N.C.
1, 12,
6, 17,
23, 34
28, 39
*) I = Input
O = Output
Semiconductor Group
1-10
Fundamental Structure
C501
2
Fundamental Structure
The C501 is fully compatible to the standard 8051 microcontroller family.
It is compatible with the 80C32/52/82C52. While maintaining all architectural and operational
characteristics of the 8051 microcontroller family, the C501 incorporates some enhancements in the
timer 2 and fail save mechanism unit.
Figure 2-6 shows a block diagram of the C501.
C501
VCC
C501-1R : ROM
C501-1E : OTP
RAM
VSS
XTAL1
XTAL2
8K x 8
256 x 8
OSC & Timing
CPU
RESET
ALE/PROG
PSEN
Port 0
8-Bit Digit. Ι /O
Timer 0
Timer 1
Timer 2
Port 0
Port 1
Port 2
Port 3
EA/VPP
Port 1
8-Bit Digit. Ι /O
Port 2
8-Bit Digit. Ι /O
Interrupt Unit
Port 3
8-Bit Digit. Ι /O
Serial Channel
(USART)
MCB03219
Figure 2-6
Block Diagram of the C501
Semiconductor Group
2-1
Fundamental Structure
C501
2.1 CPU
The C501 is efficient both as a controller and as an arithmetic processor. It has extensive facilities
for binary and BCD arithmetic and excels in its bit-handling capabilities. Efficient use of program
memory results from an instruction set consisting of 44% one-byte, 41% two-byte, and 15% three-
byte instructions. With a 12 MHz crystal, 58% of the instructions execute in 1.0 µs (24 MHz : 500 ns,
40 MHz : 300 ns).
The CPU (Central Processing Unit) of the C501 consists of the instruction decoder, the arithmetic
section and the program control section. Each program instruction is decoded by the instruction
decoder. This unit generates the internal signals controlling the functions of the individual units
within the CPU. They have an effect on the source and destination of data transfers and control the
ALU processing.
The arithmetic section of the processor performs extensive data manipulation and is comprised of
the arithmetic/logic unit (ALU), an A register, B register and PSW register.
The ALU accepts 8-bit data words from one or two sources and generates an 8-bit result under the
control of the instruction decoder. The ALU performs the arithmetic operations add, substract,
multiply, divide, increment, decrement, BDC-decimal-add-adjust and compare, and the logic
operations AND, OR, Exclusive OR, complement and rotate (right, left or swap nibble (left four)).
Also included is a Boolean processor performing the bit operations as set, clear, complement, jump-
if-not-set, jump-if-set-and-clear and move to/from carry. Between any addressable bit (or its
complement) and the carry flag, it can perform the bit operations of logical AND or logical OR with
the result returned to the carry flag.
The program control section controls the sequence in which the instructions stored in program
memory are executed. The 16-bit program counter (PC) holds the address of the next instruction to
be executed. The conditional branch logic enables internal and external events to the processor to
cause a change in the program execution sequence.
Accumulator
ACC is the symbol for the accumulator register. The mnemonics for accumulator-specific
instructions, however, refer to the accumulator simply as A.
Program Status Word
The Program Status Word (PSW) contains several status bits that reflect the current state of the
CPU.
Semiconductor Group
2-2
Fundamental Structure
C501
Special Function Register PSW (Address D0 )
H
Reset Value : 00
H
Bit No. MSB
LSB
D7
D6
D5
D4
D3
D2
D1
D0
P
H
H
H
H
H
H
H
H
D0
CY
AC
F0
RS1
RS0
OV
F1
PSW
H
Bit
Function
CY
Carry Flag
Used by arithmetic instruction.
AC
F0
Auxiliary Carry Flag
Used by instructions which execute BCD operations.
General Purpose Flag
RS1
RS0
Register Bank select control bits
These bits are used to select one of the four register banks.
RS1
RS0
Function
Bank 0 selected, data address 00 -07
0
0
1
1
0
1
0
1
H
H
Bank 1 selected, data address 08 -0F
H
H
Bank 2 selected, data address 10 -17
H
H
Bank 3 selected, data address 18 -1F
H
H
OV
Overflow Flag
Used by arithmetic instruction.
General Purpose Flag
Parity Flag
F1
P
Set/cleared by hardware after each instruction to indicate an odd/even
number of “one” bits in the accumulator, i.e. even parity.
B Register
The B register is used during multiply and divide and serves as both source and destination. For
other instructions it can be treated as another scratch pad register.
Stack Pointer
The stack pointer (SP) register is 8 bits wide. It is incremented before data is stored during PUSH
and CALL executions and decremented after data is popped during a POP and RET (RETI)
execution, i.e. it always points to the last valid stack byte. While the stack may reside anywhere in
the on-chip RAM, the stack pointer is initialized to 07 after a reset. This causes the stack to begin
H
a location = 08 above register bank zero. The SP can be read or written under software control.
H
Semiconductor Group
2-3
Fundamental Structure
C501
2.2 CPU Timing
A machine cycle of the C501 consists of 6 states (12 oscillator periods). Each state is devided into
a phase 1 half, during which the phase 1 clock is active, and a phase 2 half, during which the phase
2 clock is active. Thus, a machine cycle consists of 12 oscillator periods, numbererd S1P1 (state 1,
phase 1) through S6P2 (state 6, phase 2). Each state lasts for two oscillator periods. Typically,
arithmetic and logically operations take place during phase 1 and internal register-to-register
transfers take place during phase 2.
The diagrams in figure 2-7 show the fetch/execute timing related to the internal states and phases.
Since these internal clock signals are not user-accessible, the XTAL2 oscillator signals and the ALE
(address latch enable) signal are shown for external reference. ALE is normally activated twice
during each machine cycle: once during S1P2 and S2P1, and again during S4P2 and S5P1.
Execution of a one-cycle instruction begins at S1P2, when the op-code is latched into the instruction
register. If it is a two-byte instruction, the second reading takes place during S4 of the same
machine cycle. If it is a one-byte instruction, there is still a fetch at S4, but the byte read (which would
be the next op-code) is ignored (discarded fetch), and the program counter is not incremented. In
any case, execution is completed at the end of S6P2.
Figures 2-7 (a) and (b) show the timing of a 1-byte, 1-cycle instruction and for a 2-byte, 1-cycle
instruction.
Most C501 instructions are executed in one cycle. MUL (multiply) and DIV (divide) are the only
instructions that take more than two cycles to complete; they take four cycles. Normally two code
bytes are fetched from the program memory during every machine cycle. The only exception to this
is when a MOVX instruction is executed. MOVX is a one-byte, 2-cycle instruction that accesses
external data memory. During a MOVX, the two fetches in the second cycle are skipped while the
external data memory is being addressed and strobed. Figure 2-7 c) and d) show the timing for a
normal 1-byte, 2-cycle instruction and for a MOVX instruction.
Semiconductor Group
2-4
Fundamental Structure
C501
Figure 2-7
Fetch Execute Sequence
Semiconductor Group
2-5
Memory Organization
C501
3
Memory Organization
The C501 CPU manipulates operands in the following four address spaces:
– up to 64 Kbyte of internal/external program memory
– up to 64 Kbyte of external data memory
– 256 bytes of internal data memory
– a 128 byte special function register area
Figure 3-1 illustrates the memory address spaces of the C501.
FFFF
FFFF
H
H
External
External
Indirect
Address
Direct
Address
FF
80
FF
80
H
H
H
H
Special
Function
Register
Internal
RAM
2000
H
7F
H
1FFF
H
H
Internal
(EA = 1)
External
(EA = 0)
Internal
RAM
0000
0000
00
H
H
"Code Space"
"Data Space"
"Internal Data Space"
MCD03224
Figure 3-1
C501 Memory Map
Semiconductor Group
3-1
Memory Organization
C501
3.1 Program Memory, “Code Space”
The C501-1R/-1E has 8 Kbytes of read-only/OTP program memory, while the C501-L has no
internal program memory. The program memory can be externally expanded up to 64 Kbytes. If the
EA pin is held high, the C501 executes out of internal program memory unless the address exceeds
1FFF . Locations 2000 through FFFF are then fetched from the external program memory. If
H
H
H
the EA pin is held low, the C501 fetches all instructions from the external program memory.
3.2 Data Memory, “Data Space”
The data memory address space consists of an internal and an external memory space. The
internal data memory is divided into three physically separate and distinct blocks : the lower
128 bytes of RAM, the upper 128 bytes of RAM, and the 128 byte special function register (SFR)
area.
While the upper 128 bytes of data memory and the SFR area share the same address locations,
they are accessed through different addressing modes. The lower 128 bytes of data memory can
be accessed through direct or register indirect addressing; the upper 128 bytes of RAM can be
accessed through register indirect addressing; the special function registers are accessible through
direct addressing. Four 8-register banks, each bank consisting of eight 8-bit multi-purpose registers,
occupy locations 0 through 1F in the lower RAM area. The next 16 bytes, locations 20 through
H
H
2F , contain 128 directly addressable bit locations. The stack can be located anywhere in the
H
internal data memory address space, and the stack depth can be expanded up to 256 bytes.
The external data memory can be expanded up to 64 Kbyte and can be accessed by instructions
that use a 16-bit or an 8-bit address.
3.3 General Purpose Registers
The lower 32 locations of the internal RAM are assigned to four banks with eight general purpose
registers (GPRs) each. Only one of these banks may be enabled at a time. Two bits in the program
status word, RS0 and RS1, select the active register bank (see description of the PSW in
chapter 2). This allows fast context switching, which is useful when entering subroutines or
interrupt service routines.
The 8 general purpose registers of the selected register bank may be accessed by register
addressing. With register addressing the instruction op code indicates which register is to be used.
For indirect addressing R0 and R1 are used as pointer or index register to address internal or
external memory (e.g. MOV @R0).
Reset initializes the stack pointer to location 07 and increments it once to start from location 08
H
H
which is also the first register (R0) of register bank 1. Thus, if one is going to use more than one
register bank, the SP should be initialized to a different location of the RAM which is not used for
data storage.
Semiconductor Group
3-2
Memory Organization
C501
3.4 Special Function Registers
All registers, except the program counter and the four general purpose register banks, reside in the
special function register area.
The 27 special function register (SFR) include pointers and registers that provide an interface
between the CPU and the other on-chip peripherals. There are also 128 directly addressable bits
within the SFR area.
All SFRs are listed in table 3-1 and table 3-2.
In table 3-2 they are organized in groups which refer to the functional blocks of the C501. Table 3-3
illustrates the contents (bits) of the SFRs.
Semiconductor Group
3-3
Memory Organization
C501
Table 3-2
Special Function Registers - Functional Blocks
Block
Symbol
Name
Address Contents after
Reset
1)
CPU
ACC
B
DPH
DPL
PSW
SP
Accumulator
B-Register
Data Pointer, High Byte
Data Pointer, Low Byte
Program Status Word Register
Stack Pointer
E0
F0
83
82
00
00
00
00
00
07
H
H
H
H
H
H
H
1)
H
H
H
1)
D0
H
81
H
1)
1)
3)
3)
Interrupt
System
IE
IP
Interrupt Enable Register
Interrupt Priority Register
A8
B8
0X000000
XX000000
H
H
B
B
1)
1)
1)
1)
Ports
P0
P1
P2
P3
Port 0
Port 1
Port 2
Port 3
80
90
A0
B0
FF
H
H
H
H
H
FF
H
FF
H
FF
H
3)
Serial
Channel
PCON2)
SBUF
SCON
Power Control Register
Serial Channel Buffer Register
Serial Channel Control Register
87
99
98
0XXX0000
H
H
H
B
3)
XX
00
H
H
1)
1)
Timer 0 / TCON
Timer 1
Timer 0/1 Control Register
Timer 0, High Byte
Timer 1, High Byte
Timer 0, Low Byte
Timer 1, Low Byte
Timer Mode Register
88
00
H
H
H
H
H
H
H
TH0
TH1
TL0
TL1
TMOD
8C
8D
8A
8B
89
00
H
00
H
00
H
00
H
00
H
1)
Timer 2
T2CON
T2MOD
RC2H
RC2L
TH2
Timer 2 Control Register
Timer 2 Mode Register
Timer 2 Reload/Capture Register, High Byte CB
Timer 2 Reload/Capture Register, Low Byt CA
Timer 2 High Byte
Timer 2 Low Byte
C8
C9
00
H
H
H
H
H
H
H
3)
XXXXXXX0
B
00
00
H
00
H
H
CD
CC
TL2
00
H
3)
Pow.Sav. PCON2)
Modes
Power Control Register
87
0XXX0000
H
B
1) Bit-addressable special function registers
2) This special function register is listed repeatedly since some bits of it also belong to other functional blocks.
3) “X“ means that the value is undefined and the location is reserved
Semiconductor Group
3-4
Memory Organization
C501
Table 3-3
Contents of the SFRs, SFRs in numeric order of their addresses
Addr Register Content Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
after
Reset1)
2)
80
81
82
83
87
P0
FF
07
.7
.7
.7
.7
.6
.6
.6
.6
.5
.5
.5
.5
–
.4
.4
.4
.4
–
.3
.2
.1
.0
H
H
H
H
H
H
SP
.3
.2
.1
.0
H
H
H
DPL
DPH
PCON
00
00
.3
.2
.1
.0
.3
.2
.1
.0
0XXX- SMOD –
0000
GF1
GF0
PDE
IDLE
B
2)
H
88
89
TCON
TMOD
TL0
00
00
00
00
00
00
TF1
TR1
TF0
M1
.5
TR0
M0
.4
IE1
IT1
IE0
M1
.1
IT0
M0
.0
H
H
H
H
H
H
GATE C/T
GATE C/T
H
8A
8B
.7
.6
.3
.2
H
TL1
.7
.6
.5
.4
.3
.2
.1
.0
H
8C
8D
90
TH0
TH1
P1
.7
.6
.5
.4
.3
.2
.1
.0
H
H
.7
.6
.5
.4
.3
.2
.1
.0
2)
FF
.7
.6
.5
.4
.3
.2
.1
.0
H
H
H
H
2)
98
99
SCON
SBUF
P2
00
SM0
.7
SM1
.6
SM2
.5
REN
.4
TB8
.3
RB8
.2
TI
RI
.0
H
XX
.1
H
2)
A0
A8
FF
.7
.6
.5
.4
.3
.2
.1
.0
H
H
2)
IE
0X00-
0000
EA
–
ET2
ES
ET1
EX1
ET0
EX0
H
B
2)
2)
B0
B8
P3
IP
FF
RD
–
WR
–
T1
T0
INT1
PT1
INT0
PX1
TxD
PT0
RxD
PX0
H
H
H
XX00-
0000
PT2
PS
B
2)
C8
C9
T2CON 00
TF2
–
EXF2 RCLK TCLK EXEN2 TR2
C/T2
–
CP/
RL2
H
H
T2MOD XXXX-
XXX0
–
–
–
–
–
DCEN
H
B
CA
CB
RC2L
RC2H
TL2
00
00
00
00
.7
.7
.7
.7
.6
.6
.6
.6
.5
.5
.5
.5
.4
.4
.4
.4
.3
.3
.3
.3
.2
.2
.2
.2
.1
.1
.1
.1
.0
.0
.0
.0
H
H
H
H
H
H
CC
CD
H
TH2
H
1) X means that the value is undefined and the location is reserved
2) Bit-addressable special function registers
Semiconductor Group
3-5
Memory Organization
C501
Table 3-3
Contents of the SFRs, SFRs in numeric order of their addresses (cont’d)
Addr Register Content Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
after
Reset1)
2)
D0
E0
PSW
ACC
B
00
00
00
CY
.7
AC
.6
F0
.5
RS1
.4
RS0
.3
OV
.2
F1
.1
P
H
H
H
H
2)
.0
.0
H
2)
F0
.7
.6
.5
.4
.3
.2
.1
H
1) X means that the value is undefined and the location is reserved
2) Bit-addressable special function registers
Semiconductor Group
3-6
External Bus Interface
C501
4
External Bus Interface
The C501 allows for external memory expansion. To accomplish this, the external bus interface
common to most 8051-based controllers is employed.
4.1 Accessing External Memory
It is possible to distinguish between accesses to external program memory and external data
memory or other peripheral components respectively. This distinction is made by hardware:
accesses to external program memory use the signal PSEN (program store enable) as a read
strobe. Accesses to external data memory use RD and WR to strobe the memory (alternate
functions of P3.7 and P3.6). Port 0 and port 2 (with exceptions) are used to provide data and
address signals. In this section only the port 0 and port 2 functions relevant to external memory
accesses are described.
Fetches from external program memory always use a 16-bit address. Accesses to external data
memory can use either a 16-bit address (MOVX @DPTR) or an 8-bit address (MOVX @Ri).
4.1.1 Role of P0 and P2 as Data/Address Bus
When used for accessing external memory, port 0 provides the data byte time-multiplexed with the
low byte of the address. In this state, port 0 is disconnected from its own port latch, and the address/
data signal drives both FETs in the port 0 output buffers. Thus, in this application, the port 0 pins are
not open-drain outputs and do not require external pullup resistors.
During any access to external memory, the CPU writes FF to the port 0 latch (the special function
H
register), thus obliterating whatever information the port 0 SFR may have been holding.
Whenever a 16-bit address is used, the high byte of the address comes out on port 2, where it is
held for the duration of the read or write cycle. During this time, the port 2 lines are disconnected
from the port 2 latch (the special function register).
Thus the port 2 latch does not have to contain 1s, and the contents of the port 2 SFR are not
modified.
If an 8-bit address is used (MOVX @Ri), the contents of the port 2 SFR remain at the port 2 pins
throughout the external memory cycle. This will facilitate paging. It should be noted that, if a port 2
pin outputs an address bit that is a 1, strong pullups will be used for the entire read/write cycle and
not only for two oscillator periods.
Semiconductor Group
4-1
External Bus Interface
C501
a)
One Machine Cycle
One Machine Cycle
S1
S2
S3
S4
S5
S6
S1
S2
S3
S4
S5
S6
ALE
PSEN
RD
(A)
without
MOVX
PCH
OUT
PCH
OUT
PCH
OUT
PCH
OUT
P2
P0
INST.
IN
PCL
OUT
INST.
IN
PCL
OUT
INST.
IN
PCL
OUT
INST.
IN
PCL
OUT
INST.
IN
PCL OUT
valid
PCL OUT
valid
PCL OUT
valid
PCL OUT
valid
b)
One Machine Cycle
One Machine Cycle
S1
S2
S3
S4
S5
S6
S1
S2
S3
S4
S5
S6
ALE
PSEN
(B)
with
MOVX
RD
P2
PCH
OUT
DPH OUT OR
P2 OUT
PCH
OUT
INST.
IN
PCL
OUT
INST.
IN
DATA
IN
PCL
OUT
INST.
IN
P0
MCT03220
PCL OUT
valid
DPL or Ri
valid
PCL OUT
valid
Figure 4-1
External Program Memory Execution
Semiconductor Group
4-2
External Bus Interface
C501
4.1.2 Timing
The timing of the external bus interface, in particular the relationship between the control signals
ALE, PSEN, RD, WR and information on port 0 and port 2, is illustated in figure 4-1 a) and b).
Data memory:
in a write cycle, the data byte to be written appears on port 0 just before WR is
activated and remains there until after WR is deactivated. In a read cycle, the
incoming byte is accepted at port 0 before the read strobe is deactivated.
Program memory: Signal PSEN functions as a read strobe.
4.1.3 External Program Memory Access
The external program memory is accessed under two conditions:
– whenever signal EA is active (low) or
– whenever the program counter (PC) contains a number that is larger than 1FFF .
H
This requires the ROM-less version C501-L to have EA wired low to allow the lower 8K program
bytes to be fetched from external memory.
When the CPU is executing out of external program memory, all 8 bits of port 2 are dedicated to an
output function and may not be used for general-purpose I/O. The contents of the port 2 SFR
however is not affected. During external program memory fetches port 2 lines output the high byte
of the PC, and during accesses to external data memory they output either DPH or the port 2 SFR
(depending on whether the external data memory access is a MOVX @DPTR or a MOVX @Ri).
When the C501 executes instructions from external program memory, port 2 is at all times
dedicated to output the high-order address byte. This means that port 0 and port 2 of the C501 can
never be used as general-purpose I/O. This means that port 0 and port 2 of the C501-L can never
be used as general-purpose I/O. This also applies to the C501-1R/1E when they are operating with
external program memory only.
Semiconductor Group
4-3
External Bus Interface
C501
4.2 PSEN, Program Store Enable
The read strobe for external fetches is PSEN. PSEN is not activated for internal fetches. When the
CPU is accessing external program memory, PSEN is activated twice every cycle (except during a
MOVX instruction) no matter whether or not the byte fetched is actually needed for the current
instruction. When PSEN is activated its timing is not the same as for RD. A complete RD cycle,
including activation and deactivation of ALE and RD, takes 6 oscillator periods. A complete PSEN
cycle, including activation and deactivation of ALE and PSEN takes 3 oscillator periods. The
execution sequence for these two types of read cycles is shown in figure 4-1 a) and b).
4.3 ALE, Address Latch Enable
The main function of ALE is to provide a properly timed signal to latch the low byte of an address
from P0 into an external latch during fetches from external memory. The address byte is valid at the
negative transition of ALE. For that purpose, ALE is activated twice every machine cycle. This
activation takes place even if the cycle involves no external fetch. The only time no ALE pulse
comes out is during an access to external data memory when RD/WR signals are active. The first
ALE of the second cycle of a MOVX instruction is missing (see figure 4-1 b). Consequently, in any
system that does not use data memory, ALE is activated at a constant rate of 1/6 of the oscillator
frequency and can be used for external clocking or timing purposes.
4.4 Overlapping External Data and Program Memory Spaces
In some applications it is desirable to execute a program from the same physical memory that is
used for storing data. In the C501 the external program and data memory spaces can be combined
by AND-ing PSEN and RD. A positive logic AND of these two signals produces an active low read
strobe that can be used for the combined physical memory. Since the PSEN cycle is faster than the
RD cycle, the external memory needs to be fast enough to adapt to the PSEN cycle.
Semiconductor Group
4-4
External Bus Interface
C501
4.5 Enhanced Hooks Emulation Concept
The Enhanced Hooks Emulation Concept of the C500 microcontroller family is a new, innovative
way to control the execution of C500 MCUs and to gain extensive information on the internal
operation of the controllers. Emulation of on-chip ROM based programs is possible, too (not true for
the C509-l, because it lacks internal program memory).
Each production chip has built-in logic for the supprt of the Enhanced Hooks Emulation Concept.
Therefore, no costly bond-out chips are necessary for emulation. This also ensure that emulation
and production chips are identical.
The Enhanced Hooks TechnologyTM 1), which requires embedded logic in the C500 allows the C500
together with an EH-IC to function similar to a bond-out chip. This simplifies the design and reduces
costs of an ICE-system. ICE-systems using an EH-IC and a compatible C500 are able to emulate
all operating modes of the different versions of the C500 microcontrollers. This includes emulation
of ROM, ROM with code rollover and ROMless modes of operation. It is also able to operate in
single step mode and to read the SFRs after a break.
ICE-System Interface
to Emulation Hardware
RESET
SYSCON
PCON
RSYSCON
RPCON
EA
ALE
EH-IC
TCON
RTCON
PSEN
C500
MCU
Enhanced Hooks
Interface Circuit
Port 0
Port 2
Optional
I/O Ports
Port 3 Port 1
RPort 2 RPort 0
TEA TALE TPSEN
MCS02647
Target System Interface
Figure 4-2
Basic C500 MCU Enhanced Hooks Concept Configuration
Port 0, port 2 and some of the control lines of the C500 based MCU are used by Enhanced Hooks
Emulation Concept to control the operation of the device during emulation and to transfer
informations about the programm execution and data transfer between the external emulation
hardware (ICE-system) and the C500 MCU.
1
“Enhanced Hooks Technology” is a trademark and patent of Metalink Corporation licensed to Siemens.
Semiconductor Group
4-5
System Reset
C501
5
System Reset
5.1 Hardware Reset
The hardware reset function incorporated in the C501 allows for an easy automatic start-up at a
minimum of additional hardware and forces the controller to a predefined default state. The
hardware reset function can also be used during normal operation in order to restart the device. This
is particularly done when the power-down mode is to be terminated.
The RESET input is an active high input. An internal Schmitt trigger is used at the input for noise
rejection. Since the reset is synchronized internally, the RESET pin must be held high for at least
two machine cycles (24 oscillator periods) while the oscillator is running. With the oscillator running
the internal reset is executed during the second machine cycle and is repeated every cycle until
RESET goes low again.
During reset, pins ALE and PSEN are configured as inputs and should not be stimulated externally.
An external stimulation at these lines during reset activates several test modes which are reserved
for test purposes. This in turn may cause unpredictable output operations at several port pins.
A pullup resistor is internally connected to VCC to allow a power-up reset with an external capacitor
only. An automatic reset can be obtained when VCC is applied by connecting the RESET pin to VSS
via a capacitor. After VCC has been turned on, the capacitor must hold the voltage level at the
RESET pin for a specific time to effect a complete reset.
A correct reset leaves the processor in a defined state. The program execution starts at location
0000 . After reset is internally accomplished the port latches of ports 0, 1, 2 and 3 default in FF .
H
H
This leaves port 0 floating, since it is an open drain port when not used as data/address bus. All
other I/O port lines (ports 1, 2 and 3) output at one (1).
The content of the internal RAM of the C501 is not affected by a reset. After power-up the content
is undefined, while it remains unchanged during a reset if the power supply is not turned off.
Semiconductor Group
5-1
System Reset
C501
5.2
Hardware Reset Timing
This section describes the timing of the hardware reset signal.
The input pin RESET is sampled once during each machine cycle. This happens in state 5 phase 2.
Thus, the external reset signal is synchronized to the internal CPU timing. When the reset is found
active (high level) the internal reset procedure is started. It needs two complete machine cycles to
put the complete device to its correct reset state, i.e. all special function registers contain their
default values, the port latches contain 1’s etc. The RESET signal must be active for at least two
machine cycles; after this time the C501 remains in its reset state as long as the signal is active.
When the signal goes inactive this transition is recognized in the following state 5 phase 2 of the
machine cycle. Then the processor starts its address output (when configured for external ROM) in
the following state 5 phase 1. One phase later (state 5 phase 2) the first falling edge at pin ALE
occurs.
Figure 5-3 shows this timing for a configuration with EA = 0 (external program memory). Thus,
between the release of the RESET signal and the first falling edge at ALE there is a time period of
at least one machine cycle but less than two machine cycles.
One Machine Cycle
S4
S5
S6
S1
S2
S3
S4
S5
S6
S1
S2
S3
S4
S5
S6
S1
S2
P1 P2
RESET
PCL
OUT
Inst.
in
PCL
OUT
P0
PCH
OUT
PCH
OUT
P2
ALE
MCT02092
Figure 5-3
CPU Timing after Reset
Semiconductor Group
5-2
On-Chip Peripheral Components
C501
6
On-Chip Peripheral Components
I/O Ports
The C501 has four 8-bit I/O portst. Port 0 is an open-drain bidirectional I/O port, while ports 1 to 3
are quasi-bidirectional I/O ports with internal pullup resistors. That means, when configured as
inputs, ports 1 to 3 will be pulled high and will source current when externally pulled low. Port 0 will
float when configured as input.
The output drivers of port 0 and 2 and the input buffers of port 0 are also used for accessing external
memory. In this application, port 0 outputs the low byte of the external memory address, time
multiplexed with the byte being written or read. Port 2 outputs the high byte of the external memory
address when the address is 16 bits wide. Otherwise, the port 2 pins continue emitting the P2 SFR
contents. In this function, port 0 is not an open-drain port, but uses a strong internal pullup FET.
6.1 Parallel I/O
6.1.1 Port Structures
Digital I/O
The C501 allows for digital I/O on 32 lines grouped into 4 bidirectional 8-bit ports. Each port bit
consists of a latch, an output driver and an input buffer. Read and write accesses to the I/O ports
P0 through P3 are performed via their corresponding special function registers P0 to P3.
Semiconductor Group
6-1
On-Chip Peripheral Components
C501
Figure 6-1 shows a functional diagram of a typical bit latch and I/O buffer, which is the core of each
of the 4 I/O-ports. The bit latch (one bit in the port’s SFR) is represented as a type-D flip-flop, which
will clock in a value from the internal bus in response to a “write-to-latch” signal from the CPU. The
Q output of the flip-flop is placed on the internal bus in response to a “read-latch” signal from the
CPU. The level of the port pin itself is placed on the internal bus in response to a “read-pin” signal
from the CPU. Some instructions that read from a port (i.e. from the corresponding port SFR P0 to
P3) activate the “read-latch” signal, while others activate the “read-pin” signal.
Read
Latch
Q
Int. Bus
D
Port
Latch
Port
Driver
Circuit
Port
Pin
Write
to
Latch
Q
CLK
MCS01822
Read
Pin
Figure 6-4
Basic Structure of a Port Circuitry
Semiconductor Group
6-2
On-Chip Peripheral Components
C501
Port 1, 2 and 3 output drivers have internal pullup FET’s (see figure 6-5). Each I/O line can be used
independently as an input or output. To be used as an input, the port bit stored in the bit latch must
contain a one (1) (that means for figure 6-5: Q=0), which turns off the output driver FET n1. Then,
for ports 1, 2 and 3, the pin is pulled high by the internal pullups, but can be pulled low by an external
source. When externally pulled low the port pins source current (IIL or ITL). For this reason these
ports are sometimes called “quasi-bidirectional”.
Read
Latch
VCC
Internal
Pull Up
Arrangement
Q
Q
Pin
Int. Bus
D
Bit
Latch
Write
to
Latch
n1
CLK
MCS01823
Read
Pin
Figure 6-5
Basic Output Driver Circuit of Ports 1, 2, and 3
Semiconductor Group
6-3
On-Chip Peripheral Components
C501
In fact, the pullups mentioned before and included in figure 6-5 are pullup arrangements as shown
in figure 6-6. One n-channel pulldown FET and three pullup FETs are used:
VCC
Delay = 1 State
=1
_
<
1
p1
p2
p3
Port
Pin
n1
Q
VSS
=1
=1
Input Data
(Read Pin)
MCS03230
Figure 6-6
Output Driver Circuit of Ports 1 to 5 and 7
– The pulldown FET n1 is of n-channel type. It is a very strong driver transistor which is capable
of sinking high currents (IOL); it is only activated if a “0” is programmed to the port pin. A short
circuit to VCC must be avoided if the transistor is turned on, since the high current might destroy
the FET. This also means that no ”0“ must be programmed into the latch of a pin that is used
as input.
– The pullup FET p1 is of p-channel type. It is activated for two oscillator periods (S1P1 and
S1P2) if a 0-to-1 transition is programmed to the port pin, i.e. a “1” is programmed to the port
latch which contained a “0”. The extra pullup can drive a similar current as the pulldown FET
n1. This provides a fast transition of the logic levels at the pin.
– The pullup FET p2 is of p-channel type. It is always activated when a “1” is in the port latch,
thus providing the logic high output level. This pullup FET sources a much lower current than
p1; therefore the pin may also be tied to ground, e.g. when used as input with logic low input
level.
– The pullup FET p3 is of p-channel type. It is only activated if the voltage at the port pin is
higher than approximately 1.0 to 1.5 V. This provides an additional pullup current if a logic
high level shall be output at the pin (and the voltage is not forced lower than approximately
1.0 to 1.5 V). However, this transistor is turned off if the pin is driven to a logic low level, e.g
when used as input. In this configuration only the weak pullup FET p2 is active, which sources
the current IIL . If, in addition, the pullup FET p3 is activated, a higher current can be sourced
(ITL). Thus, an additional power consumption can be avoided if port pins are used as inputs
with a low level applied. However, the driving capability is stronger if a logic high level is
output.
Semiconductor Group
6-4
On-Chip Peripheral Components
C501
The described activating and deactivating of the four different transistors results in four states which
can be:
– input low state (IL), p2 active only
– input high state (IH) = steady output high state (SOH), p2 and p3 active
– forced output high state (FOH), p1, p2 and p3 active
– output low state (OL), n1 active
If a pin is used as input and a low level is applied, it will be in IL state, if a high level is applied, it
will switch to IH state. If the latch is loaded with “0”, the pin will be in OL state. If the latch holds a
“0” and is loaded with “1”, the pin will enter FOH state for two cycles and then switch to SOH state.
If the latch holds a “1” and is reloaded with a “1” no state change will occur.
At the beginning of power-on reset the pins will be in IL state (latch is set to “1”, voltage level on
pin is below of the trip point of p3). Depending on the voltage level and load applied to the pin, it will
remain in this state or will switch to IH (=SOH) state.
If it is is used as output, the weak pull-up p2 will pull the voltage level at the pin above p3’s trip point
after some time and p3 will turn on and provide a strong “1”. Note, however, that if the load exceeds
the drive capability of p2 (IIL), the pin might remain in the IL state and provide a week “1” until the
first 0-to-1 transition on the latch occurs. Until this the output level might stay below the trip point of
the external circuitry.
The same is true if a pin is used as bidirectional line and the external circuitry is switched from
output to input when the pin is held at “0” and the load then exceeds the p2 drive capabilities.
If the load exceeds IIL the pin can be forced to “1” by writing a “0” followed by a “1” to the port pin.
Semiconductor Group
6-5
On-Chip Peripheral Components
C501
Port 0, in contrast to ports 1, 2 and 3, is considered as “true” bidirectional, because the port 0 pins
float when configured as inputs. Thus, this port differs in not having internal pullups. The pullup FET
in the P0 output driver (see figure 6-7) is used only when the port is emitting 1 s during the external
memory accesses. Otherwise, the pullup is always off. Consequently, P0 lines that are used as
output port lines are open drain lines. Writing a “1” to the port latch leaves both output FETs off and
the pin floats. In that condition it can be used as high-impedance input. If port 0 is configured as
general I/O port and has to emit logic high-level (1), external pullups are required.
Addr./Data
VCC
Read
Latch
Control
&
=1
Port
Pin
Q
Q
Int. Bus
D
Bit
Latch
Write
to
Latch
MUX
CLK
MCS02122
Read
Pin
Figure 6-7
Port 0 Circuitry
Semiconductor Group
6-6
On-Chip Peripheral Components
C501
6.1.1.1 Port 0 and Port 2 used as Address/Data Bus
As shown in figure 6-7 and below in figure 6-8, the output drivers of ports 0 and 2 can be switched
to an internal address or address/data bus for use in external memory accesses. In this application
they cannot be used as general purpose I/O, even if not all address lines are used externally. The
switching is done by an internal control signal dependent on the input level at the EA pin and/or the
contents of the program counter. If the ports are configured as an address/data bus, the port latches
are disconnected from the driver circuit. During this time, the P2 SFR remains unchanged while the
P0 SFR has 1’s written to it. Being an address/data bus, port 0 uses a pullup FET as shown in
figure 6-7. When a 16-bit address is used, port 2 uses the additional strong pullups p1 to emit 1’s
for the entire external memory cycle instead of the weak ones (p2 and p3) used during normal port
activity.
Read
Latch
VCC
Addr.
Control
Internal
Pull Up
Arrangement
Int. Bus
D
Q
Q
Port
Pin
Bit
Latch
MUX
Write to
Latch
CLK
=1
Read
Pin
MCS02123
Figure 6-8
Port 2 Circuitry
Semiconductor Group
6-7
On-Chip Peripheral Components
C501
6.1.2
Alternate Functions
The pins of ports 1 and 3 are multifunctional. They are port pins and also serve to implement special
features as listed in table 6-4.
Figure 6-9 shows a functional diagram of a port latch with alternate function. To pass the alternate
function to the output pin and vice versa, however, the gate between the latch and driver circuit must
be open. Thus, to use the alternate input or output functions, the corresponding bit latch in the port
SFR has to contain a one (1); otherwise the pulldown FET is on and the port pin is stuck at 0. After
reset all port latches contain ones (1).
Alternate
Output
Function
VCC
Read
Latch
Internal
Pull Up
Arrangement
Pin
Q
Q
&
Int. Bus
D
Bit
Latch
Write
to
Latch
CLK
MCS01827
Read
Pin
Alternate
Input
Function
Figure 6-9
Circuitry of Ports 1 and 3
Semiconductor Group
6-8
On-Chip Peripheral Components
C501
Ports 1 and 3 are provided for several alternate functions, as listed in table 6-4:
Table 6-4
Alternate Functions of Port 1 and 3
Port
Pin
Alternate Function
P1.0
P1.1
P3.0
T2
T2EX
RxD
Input to counter 2
Capture-reload trigger of timer 2 / up down count
Serial port’s receiver data input (asynchronous) or data input/output
(synchronous)
P3.1
TxD
Serial port’s transmitter data output (asynchronous) or data clock output
(synchronous)
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
INT0
INT1
T0
T1
WR
RD
External interrupt 0 input, timer 0 gate control
External interrupt 1 input, timer 1 gate control
Timer 0 external counter input
Timer 1 external counter input
External data memory write strobe
External data momory read strobe
Semiconductor Group
6-9
On-Chip Peripheral Components
C501
6.1.3 Port Handling
6.1.3.1 Port Timing
When executing an instruction that changes the value of a port latch, the new value arrives at the
latch during S6P2 of the final cycle of the instruction. However, port latches are only sampled by
their output buffers during phase 1 of any clock period (during phase 2 the output buffer holds the
value it noticed during the previous phase 1). Consequently, the new value in the port latch will not
appear at the output pin until the next phase 1, which will be at S1P1 of the next machine cycle.
When an instruction reads a value from a port pin (e.g. MOV A, P1) the port pin is actually sampled
in state 5 phase 1 or phase 2 depending on port and alternate functions. Figure 6-10 illustrates this
port timing. lt must be noted that this mechanism of sampling once per machine cycle is also used
if a port pin is to detect an “edge”, e.g. when used as counter input. In this case an “edge” is detected
when the sampled value differs from the value that was sampled the cycle before. Therefore, there
must be met certain requirements on the pulse length of signals in order to avoid signal “edges” not
being detected. The minimum time period of high and low level is one machine cycle, which
guarantees that this logic level is noticed by the port at least once.
S4
S5
S6
S1
S2
S3
P1 P2
P1 P2
P1 P2
P1 P2
P1 P2
P1 P2
XTAL2
Input sampled:
e.g. MOV A, P1
P1 active for 1 State
(driver transistor)
Old Data
New Data
Port
MCT03231
Figure 6-10
Port Timing
Semiconductor Group
6-10
On-Chip Peripheral Components
C501
6.1.3.2 Port Loading and Interfacing
The output buffers of ports 1, 2 and 3 can drive TTL inputs directly. The maximum port load which
still guarantees correct logic output levels can be looked up in the C501 DC characteristics in
chapter 10. The corresponding parameters are VOL and VOH.
The same applies to port 0 output buffers. They do, however, require external pullups to drive
floating inputs, except when being used as the address/data bus.
When used as inputs it must be noted that the ports 1, 2 and 3 are not floating but have internal
pullup transistors. The driving devices must be capable of sinking a sufficient current if a logic low
level shall be applied to the port pin (the parameters ITL and IIL in the C501 DC characteristics
specify these currents). Port 0 has floating inputs when used for digital input.
6.1.3.3 Read-Modify-Write Feature of Ports 1,2 and 3
Some port-reading instructions read the latch and others read the pin. The instructions reading the
latch rather than the pin read a value, possibly change it, and then rewrite it to the latch. These are
called “read-modify-write”- instructions, which are listed in table 6-5. If the destination is a port or a
port pin, these instructions read the latch rather than the pin. Note that all other instructions which
can be used to read a port, exclusively read the port pin. In any case, reading from latch or pin,
respectively, is performed by reading the SFR P0, P1, P2 and P3; for example, “MOV A, P3” reads
the value from port 3 pins, while “ANL P3, #0AAH” reads from the latch, modifies the value and
writes it back to the latch.
It is not obvious that the last three instructions in table 6-5 are read-modify-write instructions, but
they are. The reason is that they read the port byte, all 8 bits, modify the addressed bit, then write
the complete byte back to the latch.
Semiconductor Group
6-11
On-Chip Peripheral Components
C501
Table 6-5
Read-Modify-Write"- Instructions
Instruction
ANL
Function
Logic AND; e.g. ANL P1, A
Logic OR; e.g. ORL P2, A
Logic exclusive OR; e.g. XRL P3, A
ORL
XRL
JBC
Jump if bit is set and clear bit; e.g. JBC P1.1, LABEL
Complement bit; e.g. CPL P3.0
Increment byte; e.g. INC P1
CPL
INC
DEC
Decrement byte; e.g. DEC P1
DJNZ
Decrement and jump if not zero; e.g. DJNZ P3, LABEL
Move carry bit to bit y of port x
Clear bit y of port x
MOV Px.y,C
CLR Px.y
SETB Px.y
Set bit y of port x
The reason why read-modify-write instructions are directed to the latch rather than the pin is to avoid
a possible misinterpretation of the voltage level at the pin. For example, a port bit might be used to
drive the base of a transistor. When a “1” is written to the bit, the transistor is turned on. If the CPU
then reads the same port bit at the pin rather than the latch, it will read the base voltage of the
transistor (approx. 0.7 V, i.e. a logic low level!) and interpret it as “0”. For example, when modifying
a port bit by a SETB or CLR instruction, another bit in this port with the above mentioned
configuration might be changed if the value read from the pin were written back to the latch.
However, reading the latch rater than the pin will return the correct value of “1”.
Semiconductor Group
6-12
On-Chip Peripheral Components
C501
6.2
Timers/Counters
The C501 contains three 16-bit timers/counters, timer 0, 1, and 2, which are useful in many
applications for timing and counting.
In “timer” function, the timer register is incremented every machine cycle. Thus one can think of it
as counting machine cycles. Since a machine cycle consists of 12 oscillator periods, the counter
rate is 1/12 of the oscillator frequency.
In “counter” function, the timer register is incremented in response to a 1-to-0 transition (falling
edge) at its corresponding external input pin, T0, T1, or T2 (alternate functions of P3.4, P3.5 and
P1.0 resp.). In this function the external input is sampled during S5P2 of every machine cycle. When
the samples show a high in one cycle and a low in the next cycle, the count is incremented. The
new count value appears in the register during S3P1 of the cycle following the one in which the
transition was detected. Since it takes two machine cycles (24 oscillator periods) to recognize a 1-
to-0 transition, the maximum count rate is 124 of the oscillator frequency. There are no restrictions
on the duty cycle of the external input signal, but to ensure that a given level is sampled at least
once before it changes, it must be held for at least one full machine cycle.
Semiconductor Group
6-13
On-Chip Peripheral Components
C501
6.2.1
Timer/Counter 0 and 1
Timer / counter 0 and 1 of the C501 are fully compatible with timer / counter 0 and 1 of the 80C51
and can be used in the same four operating modes:
Mode 0: 8-bit timer/counter with a divide-by-32 prescaler
Mode 1: 16-bit timer/counter
Mode 2: 8-bit timer/counter with 8-bit auto-reload
Mode 3: Timer/counter 0 is configured as one 8-bit timer/counter and one 8-bit timer; Timer/
counter 1 in this mode holds its count. The effect is the same as setting TR1 = 0.
External inputs INT0 and INT1 can be programmed to function as a gate for timer/counters 0 and 1
to facilitate pulse width measurements.
Each timer consists of two 8-bit registers (TH0 and TL0 for timer/counter 0, TH1 and TL1 for timer/
counter 1) which may be combined to one timer configuration depending on the mode that is
established. The functions of the timers are controlled by two special function registers TCON and
TMOD.
In the following descriptions the symbols TH0 and TL0 are used to specify the high-byte and the
low-byte of timer 0 (TH1 and TL1 for timer 1, respectively). The operating modes are described and
shown for timer 0. If not explicity noted, this applies also to timer 1.
Semiconductor Group
6-14
On-Chip Peripheral Components
C501
6.2.1.1 Timer/Counter 0 and 1 Registers
Totally six special function registers control the timer/counter 0 and 1 operation :
– TL0/TH0 and TL1/TH1 - counter registers, low and high part
– TCON and TMOD - control and mode select registers
Special Function Register TL0 (Address 8A )
H
Reset Value : 00
H
H
H
H
Special Function Register TH0 (Address 8C )
H
Reset Value : 00
Reset Value : 00
Reset Value : 00
Special Function Register TL1 (Address 8B )
H
Special Function Register TH1 (Address 8D )
H
Bit No.
MSB
7
LSB
0
6
5
4
3
2
1
8A
H
.7
.6
.5
.4
.3
.2
.1
.0
TL0
8C
H
.7
.6
.5
.4
.3
.2
.1
.0
TH0
8B
H
.7
.7
.6
.6
.5
.5
.4
.4
.3
.3
.2
.2
.1
.1
.0
.0
TL1
TH1
8D
H
Bit
Function
TLx.7-0
x=0-1
Timer/counter 0/1 low register
Operating Mode Description
0
1
2
3
“TLx” holds the 5-bit prescaler value.
“TLx” holds the lower 8-bit part of the 16-bit timer/counter value.
“TLx” holds the 8-bit timer/counter value.
TL0 holds the 8-bit timer/counter value; TL1 is not used.
THx.7-0
x=0-1
Timer/counter 0/1 high register
Operating Mode Description
0
1
2
3
“THx” holds the 8-bit timer/counter value.
“THx” holds the higher 8-bit part of the 16-bit timer/counter value
“THx” holds the 8-bit reload value.
TH0 holds the 8-bit timer value; TH1 is not used.
Semiconductor Group
6-15
On-Chip Peripheral Components
C501
Special Function Register TCON (Address 88 )
Reset Value : 00
H
H
Bit No.
MSB
7
LSB
0
6
5
4
3
2
1
8F
8E
8D
8C
8B
8A
89
88
H
H
H
H
H
H
H
H
88
H
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
TCON
The shaded bits are not used for controlling timer/counter 0 and 1.
Bit
Function
TR0
Timer 0 run control bit
Set/cleared by software to turn timer/counter 0 ON/OFF.
TF0
Timer 0 overflow flag
Set by hardware on timer/counter overflow.
Cleared by hardware when processor vectors to interrupt routine.
TR1
TF1
Timer 1 run control bit
Set/cleared by software to turn timer/counter 1 ON/OFF.
Timer 1 overflow flag
Set by hardware on timer/counter overflow.
Cleared by hardware when processor vectors to interrupt routine.
Semiconductor Group
6-16
On-Chip Peripheral Components
C501
Special Function Register TMOD (Address 89 )
Reset Value : 00
H
H
Bit No.
MSB
7
LSB
0
6
5
4
3
2
1
89
H
Gate
C/T
M1
M0
Gate
C/T
M1
M0
TMOD
Timer 1 Control
Timer 0 Control
Bit
Function
GATE
Gating control
When set, timer/counter “x” is enabled only while “INT x” pin is high and “TRx”
control bit is set.
When cleared timer “x” is enabled whenever “TRx” control bit is set.
C/T
Counter or timer select bit
Set for counter operation (input from “Tx” input pin).
Cleared for timer operation (input from internal system clock).
M1
M0
Mode select bits
M1
M0
Function
0
0
8-bit timer/counter:
“THx” operates as 8-bit timer/counter
“TLx” serves as 5-bit prescaler
0
1
1
0
16-bit timer/counter.
“THx” and “TLx” are cascaded; there is no prescaler
8-bit auto-reload timer/counter.
“THx” holds a value which is to be reloaded into “TLx” each
time it overflows
1
1
Timer 0 :
TL0 is an 8-bit timer/counter controlled by the standard
timer 0 control bits. TH0 is an 8-bit timer only controlled by
timer 1 control bits.
Timer 1 :
Timer/counter 1 stops
Semiconductor Group
6-17
On-Chip Peripheral Components
C501
6.2.1.2 Mode 0
Putting either timer/counter 0,1 into mode 0 configures it as an 8-bit timer/counter with a divide-by-
32 prescaler. Figure 6-11 shows the mode 0 operation.
In this mode, the timer register is configured as a 13-bit register. As the count rolls over from all 1’s
to all 0’s, it sets the timer overflow flag TF0. The overflow flag TF0 then can be used to request an
interrupt. The counted input is enabled to the timer when TR0 = 1 and either Gate = 0 or INT0 = 1
(setting Gate = 1 allows the timer to be controlled by external input INT0, to facilitate pulse width
measurements). TR0 is a control bit in the special function register TCON; Gate is in TMOD.
The 13-bit register consists of all 8 bits of TH0 and the lower 5 bits of TL0. The upper 3 bits of TL0
are indeterminate and should be ignored. Setting the run flag (TR0) does not clear the registers.
Mode 0 operation is the same for timer 0 as for timer 1. Substitute TR0, TF0, TH0, TL0 and INT0 for
the corresponding timer 1 signals in figure 6-11. There are two different gate bits, one for timer 1
(TMOD.7) and one for timer 0 (TMOD.3).
÷ 12
OSC
C/T = 0
C/T = 1
Interrupt
TL0
(5 Bits)
TH0
(8 Bits)
TF0
P3.4/T0
Control
&
TR0
=1
Gate
_
<
1
P3.2/INTO
MCS02143
Figure 6-11
Timer/Counter 0, Mode 0: 13-Bit Timer/Counter
Semiconductor Group
6-18
On-Chip Peripheral Components
C501
6.2.1.3 Mode 1
Mode 1 is the same as mode 0, except that the timer register is running with all 16 bits. Mode 1 is
shown in figure 6-12.
÷ 12
OSC
C/T = 0
C/T = 1
Interrupt
TL0
(8 Bits)
TH0
(8 Bits)
TF0
P3.4/T0
Control
&
TR0
=1
Gate
_
<
1
P3.2/INTO
MCS02095
Figure 6-12
Timer/Counter 0, Mode 1: 16-Bit Timer/Counter
Semiconductor Group
6-19
On-Chip Peripheral Components
C501
6.2.1.4 Mode 2
Mode 2 configures the timer register as an 8-bit counter (TL0) with automatic reload, as shown in
figure 6-13. Overflow from TL0 not only sets TF0, but also reloads TL0 with the contents of TH0,
which is preset by software. The reload leaves TH0 unchanged.
Figure 6-13
Timer/Counter 0,1, Mode 2: 8-Bit Timer/Counter with Auto-Reload
Semiconductor Group
6-20
On-Chip Peripheral Components
C501
6.2.1.5 Mode 3
Mode 3 has different effects on timer 0 and timer 1. Timer 1 in mode 3 simply holds its count. The
effect is the same as setting TR1=0. Timer 0 in mode 3 establishes TL0 and TH0 as two seperate
counters. The logic for mode 3 on timer 0 is shown in figure 6-14. TL0 uses the timer 0 control bits:
C/T, Gate, TR0, INT0 and TF0. TH0 is locked into a timer function (counting machine cycles) and
takes over the use of TR1 and TF1 from timer 1. Thus, TH0 now controls the “timer 1” interrupt.
Mode 3 is provided for applications requiring an extra 8-bit timer or counter. When timer 0 is in
mode 3, timer 1 can be turned on and off by switching it out of and into its own mode 3, or can still
be used by the serial channel as a baud rate generator, or in fact, in any application not requiring
an interrupt from timer 1 itself.
fOSC /12
C/T = 0
÷ 12
OSC
Interrupt
TL0
(8 Bits)
TF0
C/T = 1
P3.4/T0
Control
&
TR1
=1
Gate
_
<
1
P3.2/INT0
Interrupt
TH0
(8 Bits)
fOSC /12
TR1
TF1
Control
MCS02096
Figure 6-14
Timer/Counter 0, Mode 3: Two 8-Bit Timers/Counters
Semiconductor Group
6-21
On-Chip Peripheral Components
C501
6.2.2
Timer/Counter 2
Timer 2 is a 16-bit timer / counter which can operate as timer or counter. It has three operating
modes:
– 16-bit auto-reload mode (up or down counting)
– 16-bit capture mode
– Baudrate generator for the serial interface
The modes are selected by bits in the SFR T2CON (C8 ) as shown in table 6-6:
H
Table 6-6
Timer/Counter 2 - Operating Modes
RXCLK + TXCLK
CP/RL2
TR2
1
Mode
0
0
1
X
0
1
16-bit auto-reload
16-bit capture
Baud rate generator
(OFF)
1
X
X
1
0
Timer 2 consists of two 8-bit registers, TH2 and TL2. In the timer function, the TL2 register is
incremented every machine cycle. Since a machine cycle consists of 12 oscillator periods, the count
rate is 1/12 of the oscillator frequency.
In the counter function, the register is incremented in response to a 1-to-0 transition at its
corresponding external input pin, T2 (P1.0). In this function, the external input is sampled during
S5P2 of every machine cycle. When the samples show a high in one cycle and a low in the next
cycle, the count is incremented. The new value appears in the register during S3P1 of the cycle
following the one in which the transition was detected. Since it takes two machine cycles to
recognize a 1-to-0 transition, the maximum count rate is 1/24 of the oscilllator frequency. To ensure
that a given level is sampled at least once before it changes, it should be held for at least one full
machine cycle.
Semiconductor Group
6-22
On-Chip Peripheral Components
C501
6.2.2.1 Timer 2 Registers
Totally six special function registers control the timer/counter 2 operation :
– TL2/TH2 and RC2L/RC2H - counter and reload/capture registers, low and high part
– T2CON and T2MOD - control and mode select registers
Special Function Register TL2 (Address CC )
H
Reset Value : 00
H
H
H
H
Special Function Register TH2 (Address CD )
H
Reset Value : 00
Reset Value : 00
Reset Value : 00
Special Function Register RC2L (Address CA )
H
Special Function Register RC2H (Address CB )
H
Bit No.
MSB
7
LSB
0
6
5
4
3
2
1
CC
.7
.6
.5
.4
.3
.2
.1
LSB
TL2
TH2
H
CD
MSB
.6
.5
.4
.3
.2
.1
.0
H
H
CA
.7
.6
.6
.5
.5
.4
.4
.3
.3
.2
.2
.1
.1
LSB
.0
RC2L
RC2H
CB
MSB
H
Bit
Function
TL2.7-0
Timer 2 value low byte
The TL2 register holds the 8-bit low part of the 16-bit timer 2 count value.
TH2.7-0
Timer 2 value high byte
The TH2 register holds the 8-bit high part of the 16-bit timer 2 count value.
RC2L.7-0
RC2H.7-0
Reload register low byte
CRCL is the 8-bit low byte of the 16-bit reload register of timer 2.
Reload register high byte
CRCH is the 8-bit high byte of the 16-bit reload register of timer 2.
Semiconductor Group
6-23
On-Chip Peripheral Components
C501
Special Function Register T2CON (Address C8 )
H
Reset Value : 00
H
LSB
MSB
Bit No.
CF
CE
CD
CC
CB
CA
C9
C8
H
H
H
H
H
H
H
H
C8
H
TF2
EXF2 RCLK TCLK EXEN2 TR2
C/T2 CP/RL2 T2CON
Bit
Function
TF2
Timer 2 Overflow Flag.
Set by a timer 2 overflow. Must be cleared by software. TF2 will not be set when
either RCLK = 1 or TCLK = 1.
EXF2
Timer 2 External Flag.
Set when either a capture or reload is caused by a negative transition on T2EX
and EXEN2 = 1. When timer 2 interrupt is enabled, EXF2 = 1 will cause the CPU
to vector to the timer 2 interrupt routine. EXF2 must be cleared by software. EXF2
does not cause an interrupt in up/down counter mode (DCEN = 1, SFR T2MOD)
RCLK
TCLK
Receive Clock Enable.
When set, causes the serial port to use timer 2 overflow pulses for its receive
clock in serial port modes 1 and 3. RCLK = 0 causes timer 1 overflows to be used
for the receive clock.
Transmit Clock Enable.
When set, causes the serial port to use timer 2 overflow pulses for its transmit
clock in serial port modes 1 and 3. TCLK = 0 causes timer 1 overflow to be used
for the transmit clock.
EXEN2
Timer 2 External Enable.
When set, allows a capture or reload to occur as a result of a negative transition
on pin T2EX (P1.1) if timer 2 is not being used to clock the serial port. EXEN2 = 0
causes timer 2 to ignore events at T2EX.
TR2
Start / Stop Control for Timer 2.
TR2 = 1 starts timer 2.
C/T2
Timer or Counter Select for Timer 2.
C/T2 = 0 for timer function. C/T2 = 1 for external event counter (falling edge
triggered).
CP/RL2
Capture /Reload Select.
CP/RL2 = 1 causes captures to occur an negative transitions at pin T2EX if
EXEN2 = 1. CP/RL2 = 0 causes automatic reloads to occur when timer 2
overflows or negative transitions occur at pin T2EX when EXEN2 = 1. When
either RCLK = 1 or TCLK = 1, this bit is ignored and the timer is forced to auto-
reload on timer 2 overflow.
Semiconductor Group
6-24
On-Chip Peripheral Components
C501
Special Function Register T2MOD (Address C9 )
Reset Value : XXXXXXX0
B
H
Bit No.
C9
MSB
7
LSB
0
6
5
4
3
2
1
–
–
–
–
–
–
–
DCEN T2MOD
H
The shaded bits are not used for controlling timer 2.
Bit
Function
–
Not implemented, reserved for future use.
DCEN
Down Counter Enable
When set, this bit allows timer 2 to be configured as an up/down counter.
Semiconductor Group
6-25
On-Chip Peripheral Components
C501
6.2.2.2 Auto-Reload (Up or Down Counter)
Timer 2 can be programmed to count up or down when configured in its 16-bit auto-reload mode.
This feature is invoked by a bit named DCEN (Down Counter Enable, SFR T2MOD, 0C9 ). When
H
DCEN is set, timer 2 can count up or down depending on the value of pin T2EX (P1.1).
Figure 6-15 shows timer 2 automatically counting up when DCEN = 0. In this mode there are two
options selectable by bit EXEN2 in SFR T2CON.
Figure 6-15
Timer 2 Auto-Reload Mode (DCEN = 0)
If EXEN2 = 0, timer 2 counts up to FFFF and then sets the TF2 bit upon overflow. The overflow
H
also causes the timer registers to be reloaded with the 16-bit value in RC2H and RC2L. The values
in RC2H and RC2L are preset by software.
If EXEN2 = 1, a 16-bit reload can be triggered either by an overflow or by a 1-to-0 transition at the
external input T2EX (P1.1). This transition also sets the EXF2 bit. Both the TF2 and EXF2 bits can
generate an timer 2 interrupt if enabled.
Setting the DCEN bit enables timer 2 to count up or down as shown in figure 6-16. In this mode the
T2EX pin controls the direction of count.
Semiconductor Group
6-26
On-Chip Peripheral Components
C501
Figure 6-16
Timer 2 Auto-Reload Mode (DCEN = 1)
A logic 1 at T2EX makes timer 2 count up. The timer will overflow at FFFF and set the TF2 bit.
H
This overflow also causes the 16-bit value in RC2H and RC2L to be reloaded into the timer
registers, TH2 and TL2, respectively.
A logic 0 at T2EX makes timer 2 count down. Now the timer underflows when TH2 and TL2 equal
the values stored in RC2H and RC2L. The underflow sets the TF2 bit and causes FFFF to be
H
reloaded into the timer registers. The EXF2 bit toggles whenever timer 2 overflows or underflows.
This bit can be used as a 17th bit of resolution if desired. In this operating mode, EXF2 does not
flag an interrupt.
Note: P1.1/T2EX is sampled during S5P2 of every machine cycle. The next increment/decrement
of timer 2 will be done during S3P1 in the next cycle.
Semiconductor Group
6-27
On-Chip Peripheral Components
C501
6.2.2.3 Capture
In the capture mode there are two options selected by bit EXEN2 in SFR T2CON.
If EXEN2 = 0, timer 2 is a 16-bit timer or counter which upon overflow sets bit TF2 in SFR T2CON.
This bit can be used to generate an interrupt.
If EXEN2 = 1, timer 2 still does the above, but with added feature that a 1-to-0 transition at external
input T2EX causes the current value in TH2 and TL2 to be captured into RC2H and RC2L,
respectively. In addition, the transition at T2EX causes bit EXF2 in SFR T2CON to be set. The EXF2
bit, like TF2, can generate an interrupt. The capture mode is illustrated in figure 6-17.
Figure 6-17
Timer 2 in Capture Mode
The baud rate generator mode is selected by RCLK = 1 and/or TCLK = 1 in SFR T2CON. It will be
described in conjunction with the serial port.
Semiconductor Group
6-28
On-Chip Peripheral Components
C501
6.3 Serial Interface
The serial port is full duplex, meaning it can transmit and receive simultaneously. It is also receive-
buffered, meaning it can commence reception of a second byte before a previously received byte
has been read from the receive register. (However, if the first byte still hasn’t been read by the time
reception of the second byte is complete, one of the bytes will be lost). The serial port receive and
transmit registers are both accessed at special function register SBUF. Writing to SBUF loads the
transmit register, and reading SBUF accesses a physically separate receive register.
The serial port can operate in 4 modes (one synchronous mode, three asynchronous modes):
Mode 0, Shift Register (Synchronous) Mode:
Serial data enters and exits through RxD. TxD outputs the shift clock. 8 data bits are transmitted/
received: (LSB first). The baud rate is fixed at 1/12 of the oscillator frequency. (See section 6.3.4 for
more detailed information)
Mode 1, 8-Bit USART, Variable Baud Rate:
10 bits are transmitted (through TxD) or received (through RxD): a start bit (0), 8 data bits (LSB first),
and a stop bit (1). On receive, the stop bit goes into RB8 in special function register SCON. The
baud rate is variable. (See section 6.3.5 for more detailed information)
Mode 2, 9-Bit USART, Fixed Baud Rate:
11 bits are transmitted (through TxD) or received (through RxD): a start bit (0), 8 data bits (LSB first),
a programmable 9th data bit, and a stop bit (1). On transmit, the 9th data bit (TB8 in SCON) can be
assigned to the value of 0 or 1. Or, for example, the parity bit (P, in the PSW) could be moved into
TB8. On receive, the 9th data bit goes into RB8 in special function register SCON, while the stop
1
bit is ignored. The baud rate is programmable to either /32 or 1/64 of the oscillator frequency. (See
section 6.3.6 for more detailed information)
Mode 3, 9-Bit USART, Variable Baud Rate:
11 bits are transmitted (through TxD) or received (through RxD): a start bit (0), 8 data bits (LSB first),
a programmable 9th data bit, and a stop bit (1). In fact, mode 3 is the same as mode 2 in all respects
except the baud rate. The baud rate in mode 3 is variable.(See section 6.3.6 for more detailed
information)
In all four modes, transmission is initiated by any instruction that uses SBUF as a destination
register. Reception is initiated in mode 0 by the condition RI = 0 and REN = 1. Reception is initiated
in the other modes by the incomming start bit if REN = 1.
The serial interface also provides interrupt requests when transmission or reception of a frames
have been completed. The corresponding interrupt request flags are TI or RI, resp. See chapter 7
of this user manual for more details about the interrupt structure. The interrupt request flags TI and
RI can also be used for polling the serial interface, if the serial interrupt is not to be used (i.e. serial
interrupt not enabled).
Semiconductor Group
6-29
On-Chip Peripheral Components
C501
6.3.1 Multiprocessor Communications
Modes 2 and 3 have a special provision for multiprocessor communications. In these modes, 9 data
bits are received. The 9th one goes into RB8. Then comes a stop bit. The port can be programmed
such that when the stop bit is received, the serial port interrupt will be activated only if RB8 = 1. This
feature is enabled by setting bit SM2 in SCON. A way to use this feature in multiprocessor systems
is as follows.
When the master processor wants to transmit a block of data to one of several slaves, it first sends
out an address byte which identifies the target slave. An address byte differs from a data byte in
that the 9th bit is 1 in an address byte and 0 in a data byte. With SM2 = 1, no slave will be interrupted
by a data byte. An address byte, however, will interrupt all slaves, so that each slave can examine
the received byte and see if it is beeing addressed. The addressed slave will clear its SM2 bit and
prepare to receive the data bytes that will be coming. The slaves that weren’t being addressed leave
their SM2s set and go on about their business, ignoring the incoming data bytes.
SM2 has no effect in mode 0, and in mode 1 can be used to check the validity of the stop bit. In a
mode 1 reception, if SM2 = 1, the receive interrupt will not be activated unless a valid stop bit is
received.
6.3.2 Serial Port Registers
The serial port control and status register is the special function register SCON. This register
contains not only the mode selection bits, but also the 9th data bit for transmit and receive TB8 and
RB8), and the serial port interrupt bits (TI and RI).
SBUF is the receive and transmit buffer of serial interface. Writing to SBUF loads the transmit
register and initiates transmission. Reading out SBUF accesses a physically separate receive
register.
Semiconductor Group
6-30
On-Chip Peripheral Components
C501
Special Function Register SCON (Address 98 )
H
Special Function Register SBUF (Address 99 )
H
Reset Value : 00
H
Reset Value : XX
H
Bit No.
MSB
9F
LSB
9E
9D
9C
9B
9A
99
98
H
H
H
H
H
H
H
H
98
H
SM0
SM1
SM2
REN
TB8
RB8
TI
RI
SCON
SBUF
7
6
5
4
3
2
1
0
Serial Interface Buffer Register
99
H
Bit
Function
Serial port 0 operating mode selection bits
SM0
SM1
SM0
SM1
Selected operating mode
0
0
1
1
0
1
0
1
Serial mode 0 : Shift register, fixed baud rate (fOSC/6)
Serial mode 1 : 8-bit UART, variable baud rate
Serial mode 2 : 9-bit UART, fixed baud rate (fOSC/16 or fOSC/32)
Serial mode 3 : 9-bit UART, variable baud rate
SM2
Enable serial port multiprocessor communication in modes 2 and 3
In mode 2 or 3, if SM2 is set to 1 then RI will not be activated if the received 9th
data bit (RB8) is 0. In mode 1, if SM2 = 1 then RI will not be activated if a valid
stop bit was not received. In mode 0, SM2 should be 0.
REN
TB8
RB8
TI
Enable receiver of serial port
Enables serial reception. Set by software to enable serial reception. Cleared by
software to disable serial reception.
Serial port transmitter bit 9
TB8 is the 9th data bit that will be transmitted in modes 2 and 3. Set or cleared by
software as desired.
Serial port receiver bit 9
In modes 2 and 3, RB8 is the 9th data bit that was received. In mode 1, if SM2 = 0,
RB8 is the stop bit that was received. In mode 0, RB8 is not used.
Serial port transmitter interrupt flag
TI is set by hardware at the end of the 8th bit time in mode 0, or at the beginning
of the stop bit in the other modes, in any serial transmission. TI must be cleared
by software.
RI
Serial port receiver interrupt flag
RI is set by hardware at the end of the 8th bit time in mode 0, or halfway through
the stop bit time in the other modes, in any serial reception (exception see SM2).
RI must be cleared by software.
Semiconductor Group
6-31
On-Chip Peripheral Components
C501
6.3.3 Baud Rates Generation
There are several possibilities to generate the baud rate clock for the serial port depending on the
mode in which it is operating.
For clarification some terms regarding the difference between “baud rate clock” and “baud rate”
should be mentioned. The serial interface requires a clock rate which is 16 times the baud rate for
internal synchronization. Therefore, the baud rate generators have to provide a “baud rate clock” to
the serial interface which - there divided by 16 - results in the actual “baud rate”. However, all
formulas given in the following section already include the factor and calculate the final baud rate.
Further, the abrevation fOSC refers to the external clock frequency (oscillator or external input clock
operation).
The baud rate of the serial port is controlled by bit SMOD which is located in the special function
register PCON as shown below.
Special Function Register PCON (Address 87 )
Reset Value : 0XXX0000
H
B
Bit No.
MSB
7
LSB
0
6
–
5
–
4
–
3
2
1
87
H
SMOD
GF1
GF0
PDE
IDLE
PCON
The shaded bits are not used for controlling the baud rate.
Bit
Function
Double baud rate
SMOD
When set, the baud rate of serial interface in modes 1, 2, 3 is doubled. After reset
this bit is cleared.
Mode 0
The baud rate in mode 0 is fixed:
Mode 0 baud rate = oscillator frequency/12 = fOSC/12
Mode 2
The baud rate in mode 2 depends on the value of bit SMOD in special function register PCON. If
SMOD = 0 (which is the value on reset), the baud rate is fOSC/64. If SMOD = 1, the baud rate is fOSC
/
32.
Mode 2 baud rate = 2SMOD/64×(fOSC
)
Modes 1 and 3
The baud rates in mode 1 and 3 are determined by the timer overflow rate. These baud rates can
be determined by timer 1 or by timer 2 or by both (one for transmit and the other for receive).
Semiconductor Group
6-32
On-Chip Peripheral Components
C501
6.3.3.1 Using Timer 1 to Generate Baud Rates
When timer 1 is used as the baud rate generator, the baud rates in modes 1 and 3 are determined
by the timer 1 overflow rate and the value of SMOD as follows:
Modes 1,3 baud rate = 2SMOD/32×(timer 1 overflow rate)
The timer 1 interrupt should be disabled in this application. The timer itself can be configured for
either “timer” or “counter” operation, and in any of its 3 running modes. In the most typical
applications, it is configured for “timer” operation, in the auto-reload mode (high nibble of
TMOD=0010B). In that case, the baud rate is given by the formula
Modes 1,3 baud rate = 2SMOD/32×fOSC/ [12×(256–TH1)]
One can achieve very low baud rates with timer 1 by leaving the timer 1 interrupt enabled, and
configuring the timer to run as a 16-bit timer (high nibble of TMOD = 0001 ), and using the timer 1
B
interrupt to do a 16-bit software reload.
Table 6-7 lists commonly used baud rates and how they can be obtained from timer 1.
Table 6-7
Timer 1 Generated Commonly Used Baud Rates
Baud Rate
fOSC
SMOD
Timer 1
Mode
C/T
Reload
Value
Mode 0 max: 1 MHz
Mode 2 max: 375 K
Modes 1, 3: 62.5 K
19.2 K
9.6 K
4.8 K
2.4 K
1.2 K
110
12 MHz
12 MHz
12 MHz
11.059 MHz 1
11.059 MHz 0
11.059 MHz 0
11.059 MHz 0
11.059 MHz 0
X
1
1
X
X
0
0
0
0
0
0
0
0
X
X
2
2
2
2
2
2
2
1
X
X
FF
H
FD
H
FD
H
FA
H
F4
H
E8
H
6 MHz
12 MHz
0
0
72
H
110
FEEB
H
Semiconductor Group
6-33
On-Chip Peripheral Components
C501
6.3.3.2 Using Timer 2 to Generate Baud Rates
Timer 2 is selected as the baud rate generator by setting TCLK and/or RCLK in T2CON. Note then
the baud rates for transmit and receive can be simultaneously different. Setting RCLK and/or TCLK
puts timer 2 into its baud rate generator mode, as shown in figure 6-18.
Figure 6-18
Timer 2 in Baud Rate Generator Mode
The baud rate generator mode is similar to the auto-reload mode, in that rollover in TH2 causes the
timer 2 registers to be reloaded with the 16-bit value in registers RC2H and RC2L, which are preset
by software.
Now the baud rates in modes 1 and 3 are determined by timer 2’s overflow rate as follows:
Modes 1, 3 baud rate = timer 2 overflow rate/16
Semiconductor Group
6-34
On-Chip Peripheral Components
C501
The timer can be configured for either “timer” or “counter” operation: In the most typical applications,
it is configured for “timer” operation (C/T2 = 0). “Timer” operation is a little different for timer 2 when
it’s being used as a baud rate generator. Normally, as a timer it would increment every machine
cycle (thus at fOSC/12). As a baud rate generator, however, it increments every state time (fOSC/2). In
that case the baud rate is given by the formula
Modes 1,3 baud rate = fOSC/32×[65536 – (RC2H, RC2L)]
where (RC2H, RC2L) is the content of RC2H and RC2L taken as a 16-bit unsigned integer.
Note that the rollover in TH2 does not set TF2, and will not generate an interrupt. Therefore, the
timer 2 interrupt does not have to be disabled when timer 2 is in the baud rate generator mode. Note
too, that if EXEN2 is set, a 1-to-0 transition in T2EX can be used as an extra external interrupt, if
desired.
It should be noted that when timer 2 is running (TR2 = 1) in “timer” function in the baud rate
generator mode, one should not try to read or write TH2 or TL2. Under these conditions the timer
is being incremented every state time, and the results of a read or write may not be accurate. The
RC registers may be read, but shouldn’t be written to, because a write might overlap a reload and
cause write and/or reload errors. Turn the timer off (clear TR2) before accessing the timer 2 or RC
registers, in this case.
Semiconductor Group
6-35
On-Chip Peripheral Components
C501
6.3.4 Details about Mode 0
Serial data enters and exists through RxD. TxD outputs the shift clock. 8 data bits are transmitted/
received: (LSB first). The baud rate is fixed at fOSC/12.
Figure 6-19 shows a simplyfied functional diagram of the serial port in mode 0. The associated
timing is illustrated in figure 6-20.
Transmission is initiated by any instruction that uses SBUF as a destination register. The “Write to
SBUF” signal at S6P2 also loads a 1 into the 9th position of the transmit shift register and tells the
TX control block to commence a transmission. The internal timing is such that one full machine
cycle will elapse between “Write to SBUF”, and activation of SEND.
SEND enables the output of the shift register to the alternate output function line of P3.0, and also
enables SHIFT CLOCK to the alternate output function line of P3.1. SHIFT CLOCK is low during
S3, S4, and S5 of every machine cycle, and high during S6, S1 and S2. At S6P2 of every machine
cycle in which SEND is active, the contents of the transmit shift register are shifted to the right one
position.
As data bits shift out to the right, zeroes come in from the left. When the MSB of the data byte is at
the output position of the shift register, then the 1 that was initialy loaded into the 9th position, is just
to the left of the MSB, and all positions to the left of that contain zeroes. This condition flags the TX
control block to do one last shift and then deactivate SEND and set TI. Both of these actions occur
at S1P1 of the 10th machine cycle after “Write to SBUF”.
Reception is initiated by the condition REN = 1 and R1 = 0. At S6P2 of the next machine cycle, the
RX control unit writes the bits 1111 1110 to the receive shift register, and in the next clock phase
activates RECEIVE.
RECEIVE enables SHIFT CLOCK to the alternate output function line of P3.1. SHIFT CLOCK
makes transitions at S3P1 and S6P1 of every machine cycle. At S6P2 of every machine cycle in
which RECEIVE is active, the contents of the receive shift register are shifted to the left one position.
The value that comes in from the right is the value that was sampled at the P3.0 pin at S5P2 of the
same machine cycle.
As data bit comes in from the right, 1s shift out to the left. When the 0 that was initially loaded into
the rightmost position arrives at the leftmost position in the shift register, it flags the RX control block
to do one last shift and load SBUF. At S1P1 of the 10th machine cycle after the write to SCON that
cleared RI, RECEIVE is cleared and RI is set.
Semiconductor Group
6-36
On-Chip Peripheral Components
C501
Internal Bus
1
Write
to
SBUF
RXD
P3.0 Alt.
Output
Q
&
S
SBUF
Function
D
CLK
Zero Detector
Start
Shift
TX Control
Baud
_
<
1
Rate S6
Clock
Send
TXD
TX Clock
TI
&
P3.1 Alt.
Output
Function
_
<
1
Serial
Port
Interrupt
Shift
Clock
&
REN
RI
1
Start
Receive
RI
RX Control
RX Clock
Shift
1 0
1
1
1
1
1
RXD
P3.0 Alt.
Input
Input Shift Register
Function
Shift
Load
SBUF
SBUF
Read
SBUF
Internal Bus
MCS02101
Figure 6-19
Serial Interface, Mode 0, Functional Diagram
Semiconductor Group
6-37
On-Chip Peripheral Components
C501
Transmit
Receive
Figure 6-20
Serial Interface, Mode 0, Timing Diagram
Semiconductor Group
6-38
On-Chip Peripheral Components
C501
6.3.5 Details about Mode 1
Ten bits are transmitted (through TxD), or received (through RxD): a start bit (0), 8 data bits (LSB
first), and a stop bit (1). On receive, the stop bit goes into RB8 in SCON. The baud rate is
determined either by the timer 1 overflow rate, or the timer 2 overflow rate, or both (one for transmit
and the other for receive).
Figure 6-21 shows a simplified functional diagram of the serial port in mode 1. The assiociated
timings for transmit receive are illustrated in figure 6-22.
Transmission is initiated by an instruction that uses SBUF as a destination register. The “Write to
SBUF” signal also loads a 1 into the 9th bit position of the transmit shift register and flags the TX
control unit that a transmission is requested. Transmission starts at the next rollover in the divide-
by-16 counter. (Thus, the bit times are synchronized to the divide-by-16 counter, not to the “Write
to SBUF” signal).
The transmission begins with activation of SEND, which puts the start bit at TxD. One bit time later,
DATA is activated, which enables the output bit of the transmit shift register to TxD. The first shift
pulse occurs one bit time after that.
As data bits shift out to the right, zeroes are clocked in from the left. When the MSB of the data byte
is at the output position of the shift register, then the 1 that was initially loaded into the 9th position
is just to the left of the MSB, and all positions to the left of that contain zeroes. This condition flags
the TX control unit to do one last shift and then deactivate SEND and set TI. This occurs at the 10th
divide-by-16 rollover after “Write to SBUF”.
Reception is initiated by a detected 1-to-0 transition at RxD. For this purpose RxD is sampled at a
rate of 16 times whatever baud rate has been established. When a transition is detected, the divide-
by-16 counter is immediately reset, and 1FF is written into the input shift register, and reception
H
of the rest of the frame will proceed.
The 16 states of the counter divide each bit time into 16ths. At the 7th, 8th and 9th counter states
of each bit time, the bit detector samples the value of RxD. The value accepted is the value that was
seen in at latest 2 of the 3 samples. This is done for the noise rejection. If the value accepted during
the first bit time is not 0, the receive circuits are reset and the unit goes back to looking for another
1-to-0 transition. This is to provide rejection or false start bits. If the start bit proves valid, it is shifted
into the input shift register, and reception of the rest of the frame will proceed.
As data bits come in from the right, 1s shift out to the left. When the start bit arrives at the leftmost
position in the shift register, (which in mode 1 is a 9-bit register), it flags the RX control block to do
one last shift, load SBUF and RB8, and set RI. The signal to load SBUF and RB8, and to set RI, will
be generated if, and only if, the following conditions are met at the time the final shift pulse is
generated.
1) RI = 0, and
2) Either SM2 = 0, or the received stop bit = 1
If either of these two condtions is not met, the received frame is irretrievably lost. If both conditions
are met, the stop bit goes into RB8, the 8 data bit goes into SBUF, and RI is activated. At this time,
whether the above conditions are met or not, the unit goes back to looking for a 1-to-0 transition in
RxD.
Semiconductor Group
6-39
On-Chip Peripheral Components
C501
Internal Bus
1
Write
to
SBUF
Q
&
S
_
<
1
TXD
SBUF
D
CLK
Zero Detector
Shift
TX Control
Start
Data
Send
÷ 16
TX Clock
TI
_
<
1
Baud
Rate
Clock
Serial
Port
Interrupt
÷ 16
Sample
RX
RI
Load
SBUF
1-to-0
Transition
Detector
Start
RX Control
1FF
Shift
H
Bit
Detector
Input Shift Register
(9Bits)
RXD
Shift
Load
SBUF
SBUF
Read
SBUF
Internal Bus
MCS02103
Figure 6-21
Serial Interface, Mode 1, Functional Diagram
Semiconductor Group
6-40
On-Chip Peripheral Components
C501
Transmit
Receive
Figure 6-22
Serial Interface, Mode 1, Timing Diagram
Semiconductor Group
6-41
On-Chip Peripheral Components
C501
6.3.6 Details about Modes 2 and 3
Eleven bits are transmitted (through TxD), or received (through RxD): a start bit (0), 8 data bits (LSB
first), a programmable 9th data bit, and a stop bit (1). On transmit, the 9th data bit (TB8) can be
assigned the value of 0 or 1. On receive, the 9th data bit goes into RB8 in SCON. The baud rate is
programmable to either 1/32 or 1/64 the oscillator frequency in mode 2 (When bit SMOD in SFR
PCON (87 ) is set, the baud rate is fOSC/32). Mode 3 may have a variable baud rate generated from
H
either timer 1 or 2 depending on the state of TCLK and RCLK (SFR T2CON).
Figure 6-23 shows a functional diagram of the serial port in modes 2 and 3. The receive portion is
exactly the same as in mode 1. The transmit portion differs from mode 1 only in the 9th bit of the
transmit shift register. The associated timings for transmit/receive are illustrated in figure 6-24.
Transmission is initiated by any instruction that uses SBUF as a destination register. The “Write to
SBUF” signal also loads TB8 into the 9th bit position of the transmit shift register and flags the TX
control unit that a transmission is requested. Transmission starts at the next rollover in the divide-
by-16 counter. (Thus, the bit times are synchronized to the divide-by-16 counter, not to the “Write
to SBUF” signal.)
The transmision begins with activation of SEND, which puts the start bit at TxD. One bit time later,
DATA is activated, which enables the output bit of the transmit shift register to TxD. The first shift
pulse occurs one bit time after that. The first shift clocks a 1 (the stop bit) into the 9th bit position of
the shift register. Thereafter, only zeroes are clocked in. Thus, as data bits shift out to the right,
zeroes are clocked in from the left. When TB8 is at the output position of the shift register, then the
stop bit is just to the left of TB8, and all positions to the left of that contain zeroes. This conditon
flags the TX control unit to do one last shift and then deactivate SEND and set TI. This occurs at
the 11th divide-by-16 rollover after “Write to SBUF”.
Reception is initiated by a detected 1-to-0 transition at RxD. For this purpose RxD is sampled at a
rate of 16 times whatever baud rate has been established. When a transition is detected, the divide-
by-16 counter is immediately reset, and 1FF is written to the input shift register.
H
At the 7th, 8th and 9th counter states of each bit time, the bit detector samples the value of RxD.
The value accepted is the value that was seen in at least 2 of the 3 samples. If the value accepted
during the first bit time is not 0, the receive circuits are reset and the unit goes back to looking for
another 1-to-0 transition. If the start bit proves valid, it is shifted into the input shift register, and
reception of the rest of the frame will proceed.
As data bit come from the right, 1s shift out to the left. When the start bit arrives at the leftmost
position in the shift register (which in modes 2 and 3 is a 9-bit register), it flags the RX control block
to do one last shift, load SBUF and RB8, and to set RI. The signal to load SBUF and RB8, and to
set RI, will be generated if, and only if, the following conditions are met at the time the final shift
pulse is generated:
1) RI = 0, and
2) Either SM2 = 0 or the received 9th data bit = 1
If either of these conditions is not met, the received frame is irretrievably lost, and RI is not set. If
both conditions are met, the received 9th data bit goes into RB8, and the first 8 data bit goes into
SBUF. One bit time later, whether the above conditions were met or not, the unit goes back to
looking for a 1-to-0 transition at the RxDTxD input.
Note that the value of the received stop bit is irrelevant to SBUF, RB8 or RI.
Semiconductor Group
6-42
On-Chip Peripheral Components
C501
Internal Bus
TB8
Write
to
SBUF
Q
&
S
_
<
TXD
1
SBUF
D
CLK
Zero Detector
Stop Bit
Generation
Shift
Start
Data
TX Control
Send
÷ 16
TX Clock
TI
_
<
1
Baud
Rate
Clock
Serial
Port
Interrupt
÷ 16
Sample
RX Clock
RI
Load
SBUF
1-to-0
Transition
Detector
Start
RX Control
Shift
1FF
Bit
Detector
Input Shift Register
(9Bits)
RXD
Shift
Load
SBUF
SBUF
Read
SBUF
Internal Bus
MCS02105
Figure 6-23
Serial Interface, Mode 2 and 3, Functional Diagram
Semiconductor Group
6-43
On-Chip Peripheral Components
C501
Transmit
Receive
Figure 6-24
Serial Interface, Mode 2 and 3, Timing Diagram
Semiconductor Group
6-44
Interrupt System
C501
7
Interrupt System
The C501 provides 6 interrupt sources with two priority levels. Four interrupts can be generated by
the on-chip peripherals (timer 0, timer 1, timer 2 and serial interface), and two interrupts may be
triggered externally (P3.2/INT0 and P3.3/INT1).
This chapter shows the interrupt structure, the interrupt vectors and the interrupt related special
function registers. Figure 7-25 gives a general overview of the interrupt sources and illustrate the
request and the control flags which are described in the next sections.
High Priority
Low Priority
Timer 0 Overflow
TF0
TCON.5
ET0
IE.1
PT0
IP.1
Timer 1 Overflow
Timer 2 Overflow
TF1
TCON.7
TCON.0
ET1
IE.3
PT1
IP.3
TF2
T2CON.7
_
<
1
P1.1/
T2EX
EXF2
T2CON.6
ET2
IE.5
PT2
IP.5
EXEN2
T2CON.3
RI
SCON.0
_
<
1
USART
TI
ES
PS
SCON.1
IE.4
IP.4
P3.2/
INT0
IE0
TCON.1
IT0
EX0
IE.0
PX0
IP.0
TCON.0
P3.3/
INT1
IE1
TCON.3
IT1
EX1
IE.2
EA
PX1
IP.2
TCON.2
IE.7
MCS01783
Figure 7-25
Interrupt Structure
Semiconductor Group
7-1
Interrupt System
C501
7.1 Interrupt Registers
7.1.1 Interrupt Enable Register
Each interrupt vector can be individually enabled or disabled by setting or clearing the
corresponding bit in the interrupt enable register IE (interrupt enable) or T2CON. This register also
contains the global disable bit (EA), which can be cleared to disable all interrupts at once. Generally,
after reset all interrupt enable bits are set to 0. That means that the corresponding interrupts are
disabled.
Special Function Register IE (Address A8 )
H
Reset Value : 0X000000
B
LSB
MSB
Bit No.
AF
AE
–
AD
AC
ES
AB
AA
A9
A8
H
H
H
H
H
H
H
H
A8
H
EA
ET2
ET1
EX1
ET0
EX0
IE
The shaded bit is not used for interrupt control.
Bit
Function
EA
Enable/disable all interrupts.
If EAL=0, no interrupt will be acknowledged.
If EAL=1, each interrupt source is individually enabled or disabled by setting or
clearing its enable bit.
–
Not implemented. Reserved for future use.
ET2
Timer 2 overflow / external reload interrupt enable.
If ET2 = 0, the timer 2 interrupt is disabled.
If ET2 = 1, the timer 2 interrupt is enabled.
ES
Serial channel (USART) interrupt enable
If ES = 0, the serial channel interrupt 0 is disabled.
If ES = 1, the serial channel interrupt 0 is enabled.
ET1
EX1
ET0
EX0
Timer 1 overflow interrupt enable.
If ET1 = 0, the timer 1 interrupt is disabled.
If ET1 = 1, the timer 1 interrupt is enabled.
External interrupt 1 enable.
If EX1 = 0, the external interrupt 1 is disabled.
If EX1 = 1, the external interrupt 1 is enabled.
Timer 0 overflow interrupt enable.
If ET0 = 0, the timer 0 interrupt is disabled.
If ET0 = 1, the timer 0 interrupt is enabled.
External interrupt 0 enable.
If EX0 = 0, the external interrupt 0 is disabled.
If EX0 = 1, the external interrupt 0 is disabled.
Semiconductor Group
7-2
Interrupt System
C501
Special Function Register T2CON (Address C8 )
H
Reset Value : 00
H
LSB
C8
MSB
Bit No.
CF
CE
CD
CC
CB
CA
C9
H
H
H
H
H
H
H
H
C8
H
TF2
EXF2 RCLK TCLK EXEN2 TR2
C/T2 CP/RL2 T2CON
The shaded bits are not used for interrupt enable control.
Bit
EXEN2
Function
Timer 2 External Enable.
When set, allows a capture or reload to occur as a result of a negative transition on
pin T2EX (P1.1) if timer 2 is not being used to clock the serial port. EXEN2 = 0
causes timer 2 to ignore events at T2EX.
Semiconductor Group
7-3
Interrupt System
C501
7.1.2 Interrupt Request / Control Flags
The external interrupts 0 and 1 (INT0 and INT1) can each be either level-activated or negative
transition-activated, depending on bits IT0 and IT1 in register TCON. The flags that actually
generate these interrupts are bits IE0 and lE1 in TCON. When an external interrupt is generated, the
flag that generated this interrupt is cleared by the hardware when the service routine is vectored too,
but only if the interrupt was transition-activated. lf the interrupt was level-activated, then the
requesting external source directly controls the request flag, rather than the on-chip hardware.
The timer 0 and timer 1 interrupts are generated by TF0 and TF1 in register TCON, which are set
by a rollover in their respective timer/counter registers. When a timer interrupt is generated, the flag
that generated it is cleared by the on-chip hardware when the service routine is vectored too.
Special Function Register TCON (Address 88 )
H
Reset Value : 00
H
LSB
88
MSB
Bit No.
8F
8E
8D
8C
8B
8A
89
H
H
H
H
H
H
H
H
88
H
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
TCON
The shaded bits are not used for interrupt control.
Bit
Function
TF1
Timer 1 overflow flag
Set by hardware on timer/counter 1 overflow. Cleared by hardware when
processor vectors to interrupt routine.
TF0
IE1
IT1
IE0
IT0
Timer 0 overflow flag
Set by hardware on timer/counter 0 overflow. Cleared by hardware when
processor vectors to interrupt routine.
External interrupt 1 request flag
Set by hardware when external interrupt 1 edge is detected. Cleared by hardware
when processor vectors to interrupt routine.
External interrupt 1 level/edge trigger control flag
If IT1 = 0, low level triggered external interrupt 1 is selected.
If IT1 = 1, falling edge triggered external interrupt 1 is selected.
External interrupt 0 request flag
Set by hardware when external interrupt 0 edge is detected. Cleared by hardware
when processor vectors to interrupt routine.
External interrupt 0 level/edge trigger control flag
If IT0 = 0, low level triggered external interrupt 0 is selected.
If IT0 = 1, falling edge triggered external interrupt 0 is selected.
Semiconductor Group
7-4
Interrupt System
C501
The timer 2 interrupt is generated by the logical OR of bit TF2 and EXF2 in register T2CON.
Neither of these flags is cleared by hardware when the service routine is vectored to. In fact, the
service routine may have to determine whether it was TF2 or EXF2 that generated the interrupt, and
the bit will have to be cleared by software.
The serial port interrupt is generated by a logical OR of flag RI and TI in SFR SCON. Neither of
these flags is cleared by hardware when the service routine is vectored too. In fact, the service
routine will normally have to determine whether it was the receive interrupt flag or the transmission
interrupt flag that generated the interrupt, and the bit will have to be cleared by software.
Special Function Register T2CON (Address C8 )
H
Special Function Register SCON (Address. 98 )
H
Reset Value : 00
Reset Value : 00
H
H
LSB
C8
MSB
Bit No.
CF
CE
CD
CC
CB
CA
C9
H
H
H
H
H
H
H
H
C8
H
TF2
EXF2 RCLK TCLK EXEN2 TR2
9E 9D 9C 9B 9A
C/T2 CP/RL2 T2CON
Bit No.
9F
99
TI
98
RI
H
H
H
H
H
H
H
H
98
H
SM0
SM1
SM2
REN
TB8
RB8
SCON
The shaded bits are not used for interrupt request control.
Bit
Function
TF2
Timer 2 Overflow Flag.
Set by a timer 2 overflow. Must be cleared by software. TF2 will not be set when
either RCLK = 1 or TCLK = 1.
EXF2
Timer 2 External Flag.
Set when either a capture or reload is caused by a negative transition on T2EX and
EXEN2 = 1. When timer 2 interrupt is enabled, EXF2 = 1 will cause the CPU to
vector to the timer 2 interrupt routine. EXF2 must be cleared by software. EXF2
does not cause an interrupt in up/down counter mode (DCEN = 1, SFR T2MOD)
TI
Serial interface transmitter interrupt flag
Set by hardware at the end of a serial data transmission. Must be cleared by
software.
RI
Serial interface receiver interrupt flag
Set by hardware if a serial data byte has been received. Must be cleared by
software.
Semiconductor Group
7-5
Interrupt System
C501
7.1.3 Interrupt Priority Register
Each interrupt source can also be individually programmed to one of two priority levels by setting or
clearing a bit in the SFR IP (Interrupt Priority, 0: low priority, 1: high priority).
Special Function Register IP (Address B8 )
H
Reset Value : XX000000
B
LSB
MSB
Bit No.
7
6
5
4
3
2
1
0
B8
H
–
–
PT2
PS
PT1
PX1
PT0
PX0
IP
The shaded bits are not used for interrupt control.
Bit
–
Function
Not implemented. Reserved for future use.
PT2
Timer 2 Interrupt Priority Level.
If PT2 = 0, the Timer 2 interrupt has a low priority.
PS
Serial Channel Interrupt Priority Level.
If PS = 0, the Serial Channel interrupt has a low priority.
PT1
PX1
PT0
PX0
Timer 1 Overflow Interrupt Priority Level.
If PT1 = 0, the Timer 1 interrupt has a low priority.
External Interrupt 1 Priority Level.
If PX1 = 0, the external interrupt 1 has a low priority.
Timer 0 Overflow Interrupt Priority Level.
If PT0 = 0, the Timer 0 interrupt has a low priority.
External Interrupt 0 Priority Level.
If PX0 = 0, the external interrupt 0 has a low priority.
Semiconductor Group
7-6
Interrupt System
C501
7.2 Interrupt Priority Level Structure
A low-priority interrupt can itself be interrupted by a high-priority interrupt, but not by another low-
priority interrupt. A high-priority interrupt cannot be interrupted by any other interrupt source.
If two requests of different priority level are received simultaneously, the request of higher priority is
serviced. If requests of the same priority are received simultaneously, an internal polling sequence
determines which request is serviced. Thus within each priority level there is a second priority
structure determined by the polling sequence as shown in table 7-8 below:
Table 7-8
Priority-within-Level Structure
Interrupt Source
Priority
External Interrupt 0,
Timer 0 Interrupt,
External Interrupt 1,
Timer 1 Interrupt,
Serial Channel,
IE0
TF0
IE1
TF1
RI or TI
TF2 or EXF2
High
↓
Timer 2 Interrupt,
Low
Semiconductor Group
7-7
Interrupt System
C501
7.3 How Interrupts are Handled
The interrupt flags are sampled at S5P2 in each machine cycle. The sampled flags are polled during
the following machine cycle. If one of the flags was in a set condition at S5P2 of the preceeding
cycle, the polling cycle will find it and the interrupt system will generate a LCALL to the appropriate
service routine, provided this hardware-generated LCALL is not blocked by any of the following
conditions:
1. An interrupt of equal or higher priority is already in progress.
2. The current (polling) cycle is not in the final cycle of the instruction in progress.
3. The instruction in progress is RETI or any write access to registers IE or IP.
Any of these three conditions will block the generation of the LCALL to the interrupt service routine.
Condition 2 ensures that the instruction in progress is completed before vectoring to any service
routine. Condition 3 ensures that if the instruction in progress is RETI or any write access to
registers IE or IP, then at least one more instruction will be executed before any interrupt is vectored
too; this delay guarantees that changes of the interrupt status can be observed by the CPU.
The polling cycle is repeated with each machine cycle, and the values polled are the values that
were present at S5P2 of the previous machine cycle. Note that if any interrupt flag is active but not
being responded to for one of the conditions already mentioned, or if the flag is no longer active
when the blocking condition is removed, the denied interrupt will not be serviced. In other words, the
fact that the interrupt flag was once active but not serviced is not remembered. Every polling cycle
interrogates only the pending interrupt requests.
The polling cycle/LCALL sequence is illustrated in figure 7-26.
C1
C2
C3
C4
C5
S5P2
Interrupts
are polled
Long Call to Interrupt
Vector Address
Interrupt
Routine
Interrupt
is latched
MCT01859
Figure 7-26
Interrupt Response Timing Diagram
Semiconductor Group
7-8
Interrupt System
C501
Note that if an interrupt of a higher priority level goes active prior to S5P2 in the machine cycle
labeled C3 in figure 7-26 then, in accordance with the above rules, it will be vectored to during C5
and C6 without any instruction for the lower priority routine to be executed.
Thus, the processor acknowledges an interrupt request by executing a hardware-generated LCALL
to the appropriate servicing routine. In some cases it also clears the flag that generated the
interrupt, while in other cases it does not; then this has to be done by the user’s software. The
hardware clears the external interrupt flags IE0 and IE1 only if they were transition-activated. The
hardware-generated LCALL pushes the contents of the program counter onto the stack (but it does
not save the PSW) and reloads the program counter with an address that depends on the source of
the interrupt being vectored too, as shown in the following table 7-9.
Table 7-9
Interrupt Source and Vectors
Interrupt Source
Interrupt Vector Address
Interrupt Request Flags
External Interrupt 0
Timer 0 Overflow
0003
H
IE0
000B
H
TF0
External Interrupt 1
Timer 1 Overflow
0013
H
IE1
001B
H
TF1
Serial Channel
0023
H
RI / TI
TF2 / EXF2
Timer 2 Overflow / Ext. Reload
002B
H
Execution proceeds from that location until the RETI instruction is encountered. The RETI
instruction informs the processor that the interrupt routine is no longer in progress, then pops the
two top bytes from the stack and reloads the program counter. Execution of the interrupted program
continues from the point where it was stopped. Note that the RETI instruction is very important
because it informs the processor that the program left the current interrupt priority level. A simple
RET instruction would also have returned execution to the interrupted program, but it would have
left the interrupt control system thinking an interrupt was still in progress. In this case no interrupt of
the same or lower priority level would be acknowledged.
Semiconductor Group
7-9
Interrupt System
C501
7.4 External Interrupts
The external interrupts 0 and 1 can be programmed to be level-activated or negative-transition
activated by setting or clearing bit IT0, respectively in register TCON. If ITx = 0 (x = 0 or 1), external
interrupt x is triggered by a detected low level at the INTx pin. If ITx = 1, external interrupt x is
negative edge-triggered. In this mode, if successive samples of the INTx pin show a high in one
cycle and a low in the next cycle, interrupt request flag IEx in TCON is set. Flag bit IEx=1 then
requests the interrupt.
If the external interrupt 0 or 1 is level-activated, the external source has to hold the request active
until the requested interrupt is actually generated. Then it has to deactivate the request before the
interrupt service routine is completed, or else another interrupt will be generated.
The external timer 2 reload trigger interrupt request flag EXF2 will be activated by a negative
transition at pin P1.1/T2EX but only if bit EXEN2 is set.
Since the external interrupt pins are sampled once in each machine cycle, an input high or low
should be held for at least 6 oscillator periods to ensure sampling. lf the external interrupt is
transition-activated, the external source has to hold the request pin high for at least one cycle, and
then hold it low for at least one cycle to ensure that the transition is recognized so that the
corresponding interrupt request flag will be set (see figure 7-27). The external interrupt request
flags will automatically be cleared by the CPU when the service routine is called.
Figure 7-27
External Interrupt Detection
Semiconductor Group
7-10
Interrupt System
C501
7.5 Interrupt Response Time
If an external interrupt is recognized, its corresponding request flag is set at S5P2 in every machine
cycle. The value is not polled by the circuitry until the next machine cycle. If the request is active and
conditions are right for it to be acknowledged, a hardware subroutine call to the requested service
routine will be next instruction to be executed. The call itself takes two cycles. Thus a minimum of
three complete machine cycles will elapse between activation and external interrupt request and the
beginning of execution of the first instruction of the service routine.
A longer response time would be obtained if the request was blocked by one of the three previously
listed conditions. If an interrupt of equal or higer priority is already in progress, the additional wait
time obviously depends on the nature of the other interrupt’s service routine. If the instruction in
progress is not in its final cycle, the additional wait time cannot be more than 3 cycles since the
longest instructions (MUL and DIV) are only 4 cycles long; and, if the instruction in progress is RETI
or a write access to registers IE or IP the additional wait time cannot be more than 5 cycles (a
maximum of one more cycle to complete the instruction in progress, plus 4 cycles to complete the
next instruction, if the instruction is MUL or DIV).
Thus a single interrupt system, the response time is always more than 3 cycles and less than
9 cycles.
Semiconductor Group
7-11
Power Saving Modes
C501
8
Power Saving Modes
The C501 provides two basic power saving modes :
–
–
Idle mode
Power down mode.
8.1 Power Saving Mode Control Register
The two power saving modes are controlled by bits which are located in the special function
registers PCON. The SFR PCON is located at SFR address 87 .
H
The bits PDE and IDLE in SFR PCON select the power down mode or the idle mode, respectively.
If the power down mode and the idle mode are set at the same time, power down takes precedence.
Furthermore, register PCON contains two general purpose flags. For example, the flag bits GF0
and GF1 can be used to give an indication if an interrupt occurred during normal operation or during
an idle. Then an instruction that activates idle can also set one or both flag bits. When idle is
terminated by an interrupt, the interrupt service routine can examine the flag bits.
Special Function Register PCON (Address 87
H)
Reset Value : 0XXX0000
B
LSB
Bit No. MSB
7
6
–
5
–
4
–
3
2
1
0
87
SMOD
GF1
GF0
PDE
IDLE
PCON
H
The function of the shaded bit is not used for power saving mode control.
Symbol
–
Function
Reserved for future use
General purpose flag
General purpose flag
GF1
GF0
PDE
Power down enable bit
When set, starting of the power down mode is enabled
IDLE
Idle mode enable bit
When set, starting of the idle mode is enabled
Semiconductor Group
8-1
Power Saving Modes
C501
8.2 Idle Mode
In the idle mode the oscillator of the C501 continues to run, but the CPU is gated off from the clock
signal. However, the interrupt system, the serial port, and all timers are further provided with the
clock. The CPU status is preserved in its entirety: the stack pointer, program counter, program
status word, accumulator, and all other registers maintain their data during idle mode.
The reduction of power consumption, which can be achieved by this feature depends on the number
of peripherals running. If all timers are stopped and the serial interfaces are not running, the
maximum power reduction can be achieved. This state is also the test condition for the idle mode
ICC.
So, the user has to take care which peripheral should continue to run and which has to be stopped
during idle mode. Also the state of all port pins – either the pins controlled by their latches or
controlled by their secondary functions – depends on the status of the controller when entering idle
mode.
Normally, the port pins hold the logical state they had at the time when the idle mode was activated.
If some pins are programmed to serve as alternate functions they still continue to output during idle
mode if the assigned function is on. This applies to the serial interface in case it cannot finish
reception or transmission during normal operation. The control signals ALE and PSEN are hold at
logic high levels.
As in normal operation mode, the ports can be used as inputs during idle mode. Thus a capture or
reload operation can be triggered, the timers can be used to count external events, and external
interrupts will be detected.
The idle mode is a useful feature which makes it possible to "freeze" the processor's status - either
for a predefined time, or until an external event reverts the controller to normal operation, as
discussed below. The watchdog timer is the only peripheral which is automatically stopped during
idle mode.
The idle mode is entered by setting the flag bit IDLE (PCON.0).
Note:
PCON is not a bit-addressable register, so the above mentioned sequence for entering the idle
mode is obtained by byte-handling instructions, as shown in the following example:
ORL
PCON,#00000001B
;Set bit IDLE
The instruction that sets bit IDLE is the last instruction executed before going into idle mode.
There are two ways to terminate the idle mode:
– The idle mode can be terminated by activating any enabled interrupt. This interrupt will be
serviced and normally the instruction to be executed following the RETI instruction will be the
one following the instruction that sets the bit IDLE.
– The other way to terminate the idle mode, is a hardware reset. Since the oscillator is still
running, the hardware reset must be held active only for two machine cycles for a complete
reset.
Semiconductor Group
8-2
Power Saving Modes
C501
8.3 Power Down Mode
In the power down mode, the on-chip oscillator is stopped. Therefore all functions are stopped; only
the contents of the on-chip RAM and the SFR’s are maintained. The port pins controlled by their port
latches output the values that are held by their SFR’s. The port pins which serve the alternate output
functions show the values they had at the end of the last cycle of the instruction which initiated the
power-down mode. ALE and PSEN hold at logic low level (see table 9-1).
The power-down mode is entered by setting the flag bit PDE (PCON.1).
Note:
PCON is not a bit-addressable register, so the above mentioned sequence for entering the power
down mode is obtained by a byte-handling instruction, as shown in the following example:
ORL
PCON,#00000010B
;Set bit PDE
The instruction that sets bit PDE is the last instruction executed before going into power down
mode. The only exit from power down mode is a hardware reset. Reset will redefine all SFR’s, but
will not change the contents of the internal RAM.
In the power down mode of operation, VCC can be reduced to minimize power consumption. It must
be ensured, however, that VCC is not reduced before the power down mode is invoked, and that VCC
is restored to its normal operating level, before the power down mode is terminated. The reset signal
that terminates the power down mode also restarts the oscillator. The reset should not be activated
before VCC is restored to its normal operating level and must be held active long enough to allow
the oscillator to restart and stabilize (similar to power-on reset).
Semiconductor Group
8-3
Power Saving Modes
C501
8.4 State of Pins in Software Initiated Power Saving Modes
In the idle mode and in the power down mode the port pins of the C501 have a well defined status
which is listed in the following table 8-10. This state of some pins also depends on the location of
the code memory (internal or external).
Table 8-10 :
Status of External Pins During Idle and Software Power Down Mode
Outputs
Last Instruction Executed from
Internal Code Memory
Last Instruction Executed from
External Code Memory
Idle
Power Down
Low
Idle
Power Down
Low
ALE
High
High
Data
Data
Data
High
PSEN
Low
High
Low
PORT 0
PORT 1
PORT 2
PORT 3
Data
Data
Float
Data
Data
Data
Data
Address
Data
Data/alternate
outputs
Data/last output
Data/alternate
outputs
Data/last output
Semiconductor Group
8-4
OTP Memory Operation
C501
9
OTP Memory Operation of the C501-1E
The C501-1E is the OTP version of the C501-1R ROM version microcontroller. Its functionality is
fully compatible with the C501-1R functionality. This chapter describes in detail the programming
features of the C501-1E.
9.1 Programming Modes
The C501-1E is programmed by usng a modified Quick-Pulse ProgrammingTM 1) algorithm. It differs
from older methods in the value used for VPP (programming supply voltage) and in the width and
number of the ALE/PROG pulses. The C501-1E contains two signature bytes that can be read and
used by a programming system to identify the device. The signature bytes identify the manufacturer
and the type of the device.
Table 9-11 shows the logic levels for reading the signature byte, and for programming the program
memory, the encryption table, and the security bits.
Table 9-11
OTP Programming Modes
Mode
RESET PSEN
ALE/
EA/VPP P2.7
P2.6
P3.7
P3.6
PROG
Read signature
1
1
1
1
1
1
0
0
0
0
0
0
1
0
1
0
0
0
1
0
1
0
1
1
1
0
0
0
0
1
1
0
1
1
1
1
0
0
1
1
0
1
0
Program code data
Verify code data
VPP
1
Progam encryption table
Program security bit 1
Program security bit 2
VPP
VPP
VPP
Notes :
1. “0” = valid low for that pin, “1” = valid high for that pin.
2. V = 12.75 V ± 0.25V
PP
3. V = 5 V ± 10% during programming and verification.
CC
4. ALE/PROG receives 25 programming pulses while V is held at 12.75 V. Each programming pulse is low for
PP
100 µs (± 10 µs) and high for a minimum of 10 µs.
1
TM
Quick-Pulse Programming is a trademark phrase of Intel Corporation
Semiconductor Group
9-1
OTP Memory Operation
C501
9.2 Quick-Pulse Programming
The setup for microcontroller quick-pulse programming is shown in figure 9-28. Note that the
C501-1E is running with a 4 to 6 MHz oscillator The reason the oscillator needs to be running is that
the device is executing internal address and program data transfers.
+5 V
A0 - A7
1
Port 1
VCC
C501-1E
RESET
Programming
Data
Port 0
1
1
P3.6
P3.7
V
EA/
+12.75 V
PP
25 x 100µs
ALE/PROG
PSEN
P2.7
Low Pulses
0
XTAL2
4 - 6 MHz
1
0
P2.6
XTAL1
VSS
P2.0 - P2.4
A8 - A12
MCS03232
Figure 9-28
C501-1E OTP Memory Programming Configuration
The address of the OTP memory location to be programmed is applied to port 1 and 2. The code
byte to be programmed into that location is applied to port 0. RESET, PSEN and pins of port 2 and
3 specified in table 9-11 are held at the “Program code data“ levels. The ALE/PROG signal is
pulsed low 25 times as shown in figure 9-29.
25 Pulses
ALE/PROG
10
µ
s min.
µ
µ
1
ALE/PROG
0
MCT03234
Figure 9-29
C501-1E ALE/PROG Waveform
Semiconductor Group
9-2
OTP Memory Operation
C501
Note that the EA/VPP pin must not be allowed to go above the maximum specified VPP level for any
amount of time. Even a narrow glitch above that voltage can cause permanent damage to the
device. The VPP source should be well regulated and free of glitches and overshoots.
9.3 Encryption Table
The encryption table feature of the C501-1E is a feature that protects the program code in the OTP
memory from being easily read by anyone other than the programmer. The encryption table is
32 byte of code that is exclusive NORed with the OTP memory data as it is read out. The first byte
is XNORed with the first location read, the second with the second read, etc. through the 32nd byte
read. The 33rd read byte is XNORED with the first byte of the encryption table, the 34rd with the
second, etc. and so on in 32-byte groups.
After the encryption table has been programmed, the user has to know its contents in order to
correctly decode the program code stored in the OTP memory. The encryption table itself cannot be
read out.
For programming of the encryption table, the 25 pulse programming sequence must be repeated for
addresses 0 through 1F , using the “Program encryption table“ levels. After the encryption table is
H
programmed, verification cycles will produce only encrypted data.
9.4 Security Bits
There are two security bits on the C501-1E that, when set, prevent the OTP program memory from
being read out or programmed further. For programming of the security bits, the 25 pulse
programming sequence must be repeated using the “Program security bit“ levels as specified in
table 9-11. After the first security bit is programmed, further programming of the OTP memory and
the encryption table is disabled. However, the other security bit can still be programmed. With only
security bit one programmed, the OTP memory can still be read out for program verification. After
the second security bit is programmed, it is no longer possible to read out (verify) the OTP memory
content.
Semiconductor Group
9-3
OTP Memory Operation
C501
9.5 OTP Memory Verification
If security bit 2 has not been programmed, the on-chip OTP program memory can be read out for
program verification. The address of the OTP program memory locations to be read is applied to
ports 1 and 2 as shown in figure 9-30. The other pins are held at the “Verify code data“ levels
indicated in table 9-11. The contents of the address location will be emitted on port 0. External
pullups are required on port 0 for this operation.
+5 V
A0 - A7
1
Port 1
VCC
C501-1E
10 kΩ
RESET
1
1
P3.6
P3.7
Programming
Data
Port 0
V
EA/
1
PP
XTAL2
ALE/PROG
PSEN
P2.7
1
0
4 - 6 MHz
0 Enable
0
P2.6
XTAL1
VSS
P2.0 - P2.4
A8 - A12
MCS03235
Figure 9-30
C501-1E OTP Memory Verification
If the encryption table has been programmed, the data presented at port 0 will be the exclusive NOR
of the program byte with one of the encryption bytes. The user will have to know the encryption table
contents in order to correctly decode the verification data. The encryption table itself cannot be read
out.
Reading the SIgnature Bytes
The signature bytes are read by the same procedure as a normal verification of locations 30 and
H
31 , except that P3.6 and P3.7 need to be pulled to a logic low level. The values of the signature
H
bytes are :
Address 30 : E0 indicates manufacturer
H
H
Address 31 : 71 indicates C501-1E
H
H
Semiconductor Group
9-4
Device Specifications
C501
10
Device Specifications
10.1 Absolute Maximum Ratings
Ambient temperature under bias (TA) ......................................................... – 40 to 85 °C
Storage temperature (Tstg) .......................................................................... – 65 °C to 150 °C
Voltage on VCC pins with respect to ground (VSS) ....................................... – 0.5 V to 6.5 V
Voltage on any pin with respect to ground (VSS)......................................... – 0.5 V to VCC +0.5 V
Input current on any pin during overload condition..................................... – 10 mA to 10 mA
Absolute sum of all input currents during overload condition ..................... I 100 mA I
Power dissipation........................................................................................ TBD
Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent
damage of the device. This is a stress rating only and functional operation of the device at
these or any other conditions above those indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating conditions for longer
periods may affect device reliability. During overload conditions (VIN > VCC or VIN < VSS) the
Voltage on VCC pins with respect to ground (VSS) must not exceed the values defined by the
absolute maximum ratings.
Semiconductor Group
10-1
Device Specifications
C501
10.2 DC Characteristics for C501-L / C501-1R
CC = 5 V + 10 %, – 15 %; VSS = 0 V; TA = 0 °C to 70 °C
V
for the SAB-C501
TA = – 40 °C to 85 °C for the SAF-C501
Parameter
Symbol
Limit Values
max.
Unit Test Condition
min.
Input low voltage (except EA, VIL
– 0.5
0.2 VCC – 0.1 V
–
RESET)
Input low voltage (EA)
VIL 1
– 0.5
– 0.5
0.2 VCC – 0.3 V
0.2 VCC + 0.1 V
–
–
–
Input low voltage (RESET)
VIL 2
VIH
Input high voltage (except
XTAL1, EA, RESET)
0.2 VCC + 0.9 VCC + 0.5
V
Input high voltage to XTAL1 VIH 1
0.7 VCC
0.6 VCC
V
CC + 0.5
CC + 0.5
V
V
Input high voltage to EA,
RESET
VIH 2
V
–
Output low voltage
(ports 1, 2, 3)
VOL
–
–
0.45
0.45
V
V
V
V
IOL = 1.6 mA 1)
IOL = 3.2 mA 1)
Output low voltage
(port 0, ALE, PSEN)
VOL 1
VOH
Output high voltage
(ports 1, 2, 3)
2.4
0.9 VCC
–
–
I
I
OH = – 80 µA,
OH = – 10 µA
Output high voltage
(port 0 in external bus mode,
ALE, PSEN)
VOH 1
2.4
0.9 VCC
–
–
I
I
OH = – 800 µA 2),
OH = – 80 µA 2)
Logic 0 input current
(ports 1, 2, 3)
IIL
– 10
– 65
–
– 50
– 650
± 1
µA
VIN = 0.45 V
Logical 1-to-0 transition
current (ports 1, 2, 3)
ITL
ILI
µA VIN = 2 V
Input leakage current
(port 0, EA)
µA 0.45 < VIN < VCC
Pin capacitance
CIO
–
10
pF
fC = 1 MHz,
TA = 25 °C
Power supply current:
Active mode, 12 MHz 7) ICC
–
–
–
–
–
–
–
21
4.8
mA VCC = 5 V, 4)
mA VCC = 5 V, 5)
mA VCC = 5 V, 4)
mA VCC = 5 V, 5)
mA VCC = 5 V, 4)
mA VCC = 5 V, 5)
Idle mode, 12 MHz7)
Active mode, 24 MHz 7) ICC
Idle mode, 24 MHz7)
ICC
36.2
8.2
56.5
12.7
50
ICC
Active mode, 40 MHz 7) ICC
Idle mode, 40 MHz7)
Power Down Mode
ICC
IPD
µA
V
CC = 2 … 5.5 V 3)
Notes see page 10-4
Semiconductor Group
10-2
Device Specifications
C501
10.3 DC Characteristics for C501-1E
CC = 5 V + 10 %, – 15 %; VSS = 0 V;
V
TA = 0 °C to 70 °C
for the SAB-C501
TA = – 40 °C to 85 °C for the SAF-C501
Parameter
Symbol
Limit Values
max.
Unit Test Condition
min.
Input low voltage (except
EA/VPP, RESET)
VIL
– 0.5
0.2 VCC – 0.1 V
–
Input low voltage (EA/VPP)
Input low voltage (RESET)
VIL 1
VIL 2
VIH
– 0.5
– 0.5
0.1 VCC – 0.1 V
0.2 VCC + 0.1 V
–
–
–
Input high voltage (except
XTAL1, EA/VPP, RESET)
0.2 VCC + 0.9 VCC + 0.5
V
Input high voltage to XTAL1 VIH 1
0.7 VCC
0.6 VCC
V
CC + 0.5
CC + 0.5
V
V
Input high voltage to EA/VPP, VIH 2
V
–
RESET
Output low voltage
(ports 1, 2, 3)
VOL
–
–
0.45
0.45
V
V
V
V
IOL = 1.6 mA 1)
IOL = 3.2 mA 1)
Output low voltage
(port 0, ALE/PROG, PSEN)
VOL 1
VOH
Output high voltage
(ports 1, 2, 3)
2.4
0.9 VCC
–
–
I
I
OH = – 80 µA,
OH = – 10 µA
Output high voltage
(port 0 in external bus mode,
ALE/PROG, PSEN)
VOH 1
2.4
0.9 VCC
–
–
I
I
OH = – 800 µA 2),
OH = – 80 µA 2)
Logic 0 input current
(ports 1, 2, 3)
IIL
– 10
– 65
–
– 50
– 650
± 1
µA
VIN = 0.45 V
Logical 1-to-0 transition
current (ports 1, 2, 3)
ITL
ILI
µA VIN = 2 V
Input leakage current
(port 0, EA/VPP)
µA 0.45 < VIN < VCC
Pin capacitance
CIO
–
10
pF
fC = 1 MHz,
TA = 25 °C
Power supply current:
Active mode, 12 MHz 7) ICC
–
–
–
–
–
21
18
36.2
20
50
mA VCC = 5 V, 4)
mA VCC = 5 V, 5)
mA VCC = 5 V, 4)
mA VCC = 5 V, 5)
Idle mode, 12 MHz7)
ICC
Active mode, 24 MHz 7) ICC
Idle mode, 24 MHz7)
Power Down Mode
ICC
IPD
µA
V
CC = 2 … 5.5 V 3)
Notes see next page.
Semiconductor Group
10-3
Device Specifications
C501
Notes:
1)
Capacitive loading on ports 0 and 2 may cause spurious noise pulses to be superimposed on the VOL of ALE
and port 3. The noise is due to external bus capacitance discharging into the port 0 and port 2 pins when these
pins make 1-to-0 transitions during bus operation. In the worst case (capacitive loading > 100 pF), the noise
pulse on ALE line may exceed 0.8 V. In such cases it may be desirable to qualify ALE with a schmitt-trigger,
or use an address latch with a schmitt-trigger strobe input.
2)
3)
4)
Capacitive loading on ports 0 and 2 may cause the VOH on ALE and PSEN to momentarily fall bellow the
0.9 VCC specification when the address lines are stabilizing.
I
PD (Power Down Mode) is measured under following conditions:
EA = Port0 = VCC; RESET = VSS; XTAL2 = N.C.; XTAL1 = VSS; all other pins are disconnected.
I
CC (active mode) is measured with:
XTAL1 driven with tCLCH, tCHCL = 5 ns, VIL = VSS + 0.5 V, VIH = VCC – 0.5 V; XTAL2 = N.C.;
EA = Port0 = RESET= VCC; all other pins are disconnected. ICC would be slightly higher if a crystal oscillator is
used (appr. 1 mA).
5)
7)
I
CC (Idle mode) is measured with all output pins disconnected and with all peripherals disabled;
XTAL1 driven with tCLCH, tCHCL = 5 ns, VIL = VSS + 0.5 V, VIH = VCC – 0.5 V; XTAL2 = N.C.;
RESET = EA = VSS; Port0 = VCC; all other pins are disconnected;
I
CC max at other frequencies is given by:
active mode:
idle mode:
I
I
CC = 1.27 x fOSC + 5.73
CC = 0.28 x fOSC + 1.45 (C501-L and C501-1R only)
where fOSC is the oscillator frequency in MHz. ICC values are given in mA and measured at VCC = 5 V.
Semiconductor Group
10-4
Device Specifications
C501
10.4 AC Characteristics for C501-L / C501-1R / C501-1E
CC = 5 V + 10 %, – 15 %; VSS = 0 V TA = 0 °C to 70 °C
TA = – 40 °C to 85 °C for the SAF-C501
V
for the SAB-C501
(CL for port 0, ALE and PSEN outputs = 100 pF; CL for all other outputs = 80 pF)
Program Memory Characteristics
Parameter
Symbol
Limit Values
Variable Clock
1/tCLCL = 3.5 MHz to 12 MHz
Unit
12 MHz
Clock
min. max. min.
max.
ALE pulse width
tLHLL
tAVLL
tLLAX
tLLIV
127
43
30
–
–
2tCLCL – 40
–
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Address setup to ALE
Address hold after ALE
ALE low to valid instr in
ALE to PSEN
–
t
t
CLCL – 40
CLCL – 53
–
–
–
233
–
–
4tCLCL – 100
tLLPL
tPLPH
tPLIV
58
215
–
t
CLCL – 25
–
PSEN pulse width
PSEN to valid instr in
–
3tCLCL – 35
–
150
–
–
0
–
3tCLCL – 100
Input instruction hold after PSEN tPXIX
0
–
*)
Input instruction float after PSEN tPXIZ
–
63
–
tCLCL – 20
*)
Address valid after PSEN
Address to valid instr in
Address float to PSEN
tPXAV
tAVIV
tAZPL
75
–
t
CLCL – 8
–
302
–
–
0
5tCLCL – 115
0
–
*) Interfacing the C501 to devices with float times up to 75 ns is permissible. This limited bus contention will not
cause any damage to port 0 Drivers.
Semiconductor Group
10-5
Device Specifications
C501
AC Characteristics for C501-L / C501-1R / C501-1E (cont’d)
External Data Memory Characteristics
Parameter
Symbol
Limit Values
Unit
12 MHz
Clock
Variable Clock
1/tCLCL = 3.5 MHz to 12 MHz
min. max. min.
max.
RD pulse width
tRLRH
tWLWH
tLLAX2
tRLDV
tRHDX
tRHDZ
tLLDV
400
400
30
–
–
6tCLCL – 100
6tCLCL – 100
–
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
WR pulse width
–
–
Address hold after ALE
RD to valid data in
–
t
CLCL – 53
–
252
–
–
5tCLCL – 165
–
Data hold after RD
0
0
Data float after RD
–
97
517
585
300
–
–
2tCLCL – 70
8tCLCL – 150
9tCLCL – 165
3tCLCL + 50
–
ALE to valid data in
Address to valid data in
ALE to WR or RD
–
–
tAVDV
tLLWL
tAVWL
tWHLH
tQVWX
tQVWH
tWHQX
tRLAZ
–
–
200
203
43
33
433
33
–
3tCLCL – 50
4tCLCL – 130
Address valid to WR or RD
WR or RD high to ALE high
Data valid to WR transition
Data setup before WR
Data hold after WR
Address float after RD
123
–
t
t
CLCL – 40
CLCL – 50
tCLCL + 40
–
–
–
0
–
7tCLCL – 150
CLCL – 50
–
t
0
–
External Clock Drive Characteristics
Parameter
Symbol
Limit Values
Variable Clock
Unit
Freq. = 3.5 MHz to 12 MHz
min.
83.3
20
20
–
max.
Oscillator period
High time
tCLCL
tCHCX
tCLCX
tCLCH
tCHCL
285.7
ns
ns
ns
ns
ns
t
CLCL – tCLCX
CLCL – tCHCX
Low time
t
Rise time
20
20
Fall time
–
Semiconductor Group
10-6
Device Specifications
C501
10.5 AC Characteristics for C501-L24 / C501-1R24 / C501-1E24
CC = 5 V + 10 %, – 15 %; VSS = 0 V TA = 0 °C to 70 °C for the SAB-C501
TA = – 40 °C to 85 °C for the SAF-C501
V
(CL for port 0, ALE and PSEN outputs = 100 pF; CL for all other outputs = 80 pF)
Program Memory Characteristics
Parameter
Symbol
Limit Values
Variable Clock
1/tCLCL = 3.5 MHz to 24 MHz
Unit
24 MHz
Clock
min. max. min.
max.
ALE pulse width
tLHLL
tAVLL
tLLAX
tLLIV
43
17
17
–
–
2tCLCL – 40
–
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Address setup to ALE
Address hold after ALE
ALE low to valid instr in
ALE to PSEN
–
t
t
CLCL – 25
CLCL – 25
–
–
–
80
–
–
4tCLCL – 87
tLLPL
tPLPH
tPLIV
22
95
–
t
CLCL – 20
–
PSEN pulse width
PSEN to valid instr in
–
3tCLCL – 30
–
60
–
–
0
–
3tCLCL – 65
Input instruction hold after PSEN tPXIX
0
–
*)
Input instruction float after PSEN tPXIZ
–
32
–
tCLCL – 10
*)
Address valid after PSEN
Address to valid instr in
Address float to PSEN
tPXAV
tAVIV
tAZPL
37
–
t
CLCL – 5
–
148
–
–
0
5tCLCL – 60
0
–
*) Interfacing the C501 to devices with float times up to 37 ns is permissible. This limited bus contention will not
cause any damage to port 0 Drivers.
Semiconductor Group
10-7
Device Specifications
C501
AC Characteristics for C501-L24 / C501-1R24 / C501-1E24 (cont’d)
External Data Memory Characteristics
Parameter
Symbol
Limit Values
Unit
24 MHz
Clock
Variable Clock
1/tCLCL = 3.5 MHz to 24 MHz
min. max. min.
max.
RD pulse width
tRLRH
tWLWH
tLLAX2
tRLDV
tRHDX
tRHDZ
tLLDV
180
180
15
–
–
6tCLCL – 70
6tCLCL – 70
–
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
WR pulse width
–
–
Address hold after ALE
RD to valid data in
–
t
CLCL – 27
–
118
–
–
5tCLCL – 90
–
Data hold after RD
0
0
Data float after RD
–
63
200
220
175
–
–
2tCLCL – 20
8tCLCL – 133
9tCLCL – 155
3tCLCL + 50
–
ALE to valid data in
Address to valid data in
ALE to WR or RD
–
–
tAVDV
tLLWL
tAVWL
tWHLH
tQVWX
tQVWH
tWHQX
tRLAZ
–
–
75
67
17
5
3tCLCL – 50
4tCLCL – 97
Address valid to WR or RD
WR or RD high to ALE high
Data valid to WR transition
Data setup before WR
Data hold after WR
Address float after RD
67
–
t
t
CLCL – 25
CLCL – 37
tCLCL + 25
–
–
–
0
170
15
–
–
7tCLCL – 122
CLCL – 27
–
t
0
–
External Clock Drive Characteristics
Parameter
Symbol
Limit Values
Variable Clock
Unit
Freq. = 3.5 MHz to 24 MHz
min.
41.7
12
12
–
max.
Oscillator period
High time
tCLCL
tCHCX
tCLCX
tCLCH
tCHCL
285.7
ns
ns
ns
ns
ns
t
CLCL – tCLCX
CLCL – tCHCX
Low time
t
Rise time
12
12
Fall time
–
Semiconductor Group
10-8
Device Specifications
C501
10.6 AC Characteristics for C501-L40 / C501-1R40
CC = 5 V + 10 %, – 15 %; VSS = 0 V TA = 0 °C to 70 °C
TA = – 40 °C to 85 °C for the SAF-C501
V
for the SAB-C501
(CL for port 0, ALE and PSEN outputs = 100 pF; CL for all other outputs = 80 pF)
Program Memory Characteristics
Parameter
Symbol
Limit Values
Variable Clock
1/tCLCL = 3.5 MHz to 40 MHz
Unit
40 MHz
Clock
min. max. min.
max.
ALE pulse width
tLHLL
tAVLL
tLLAX
tLLIV
35
10
10
–
–
2 tCLCL– 15
–
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Address setup to ALE
Address hold after ALE
ALE low to valid instr in
ALE to PSEN
–
t
t
CLCL– 15
CLCL– 15
–
–
–
55
–
–
4 tCLCL– 45
tLLPL
tPLPH
tPLIV
10
60
–
t
CLCL– 15
–
PSEN pulse width
PSEN to valid instr in
–
3 tCLCL– 15
–
25
–
–
0
–
3 tCLCL– 50
Input instruction hold after PSEN tPXIX
0
–
*)
Input instruction float after PSEN tPXIZ
–
20
–
tCLCL– 5
*)
Address valid after PSEN
Address to valid instr in
Address float to PSEN
tPXAV
tAVIV
tAZPL
20
–
t
CLCL– 5
–
65
–
–
5 tCLCL– 60
– 5
– 5
–
*) Interfacing the C501 to devices with float times up to 25ns is permissible. This limited bus contention will not
cause any damage to port 0 Drivers.
Semiconductor Group
10-9
Device Specifications
C501
AC Characteristics for C501-L40 / C501-1R40 (cont’d)
External Data Memory Characteristics
Parameter
Symbol
Limit Values
Unit
40 MHz
Clock
Variable Clock
1/tCLCL = 3.5 MHz to 40 MHz
min. max. min.
max.
RD pulse width
tRLRH
tWLWH
tLLAX2
tRLDV
tRHDX
tRHDZ
tLLDV
120
120
10
–
–
6 tCLCL– 30
6 tCLCL– 30
–
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
WR pulse width
–
–
Address hold after ALE
RD to valid data in
–
t
CLCL– 15
–
75
–
–
5 tCLCL– 50
–
Data hold after RD
0
0
Data float after RD
–
38
150
150
90
–
–
2 tCLCL– 12
8 tCLCL– 50
9 tCLCL– 75
3 tCLCL+ 15
–
ALE to valid data in
Address to valid data in
ALE to WR or RD
–
–
tAVDV
tLLWL
tAVWL
tWHLH
tQVWX
tQVWH
tWHQX
tRLAZ
–
–
60
70
10
5
3 tCLCL– 15
4 tCLCL– 30
Address valid to WR or RD
WR or RD high to ALE high
Data valid to WR transition
Data setup before WR
Data hold after WR
Address float after RD
40
–
t
t
CLCL– 15
CLCL– 20
tCLCL+ 15
–
–
–
0
125
5
–
7 tCLCL– 50
CLCL– 20
–
t
–
0
–
External Clock Drive Characteristics
Parameter
Symbol
Limit Values
Variable Clock
Unit
Freq. = 3.5 MHz to 40 MHz
min.
25
10
10
–
max.
Oscillator period
High time
tCLCL
tCHCX
tCLCX
tCLCH
tCHCL
285.7
ns
ns
ns
ns
ns
t
CLCL – tCLCX
CLCL – tCHCX
Low time
t
Rise time
10
10
Fall time
–
Semiconductor Group
10-10
Device Specifications
C501
t LHLL
ALE
PSEN
Port 0
t AVLL
t PLPH
t LLPL
t
LLIV
t
PLIV
t AZPL
t LLAX
t
PXAV
PXIZ
t
t PXIX
A0 - A7
Instr.IN
A0 - A7
t
AVIV
Port 2
A8 - A15
A8 - A15
MCT00096
Program Memory Read Cycle
Semiconductor Group
10-11
Device Specifications
C501
tWHLH
ALE
PSEN
RD
t LLDV
t LLWL
t RLRH
t RLDV
t AVLL
tRHDZ
t LLAX2
t RLAZ
tRHDX
A0 - A7 from
Ri or DPL
A0 - A7
from PCL
Instr.
IN
Port 0
Data IN
tAVWL
t AVDV
Port 2
P2.0 - P2.7 or A8 - A15 from DPH
A8 - A15 from PCH
MCT00097
Data Memory Read Cycle
Semiconductor Group
10-12
Device Specifications
C501
tWHLH
ALE
PSEN
WR
t LLWL
t WLWH
tQVWX
t AVLL
tWHQX
t LLAX2
tQVWH
A0 - A7 from
Ri or DPL
A0 - A7
from PCL
Instr.IN
Port 0
Port 2
Data OUT
tAVWL
P2.0 - P2.7 or A8 - A15 from DPH
A8 - A15 from PCH
MCT00098
Data Memory Write Cycle
tCLCL
V
CC- 0.5V
0.45V
0.7 VCC
0.2 VCC- 0.1
tCLCX
tCHCX
MCT00033
tCHCL
tCLCH
External Clock Drive at XTAL2
Semiconductor Group
10-13
Device Specifications
C501
10.7 ROM Verification Characteristics for C501-1R
ROM Verification Mode 1
Parameter
Symbol
Limit Values
Unit
min.
max.
48tCLCL
48tCLCL
48tCLCL
6
Address to valid data
ENABLE to valid data
Data float after ENABLE
Oscillator frequency
tAVQV
tELQV
–
–
0
4
ns
ns
tEHQZ
1/tCLCL
ns
MHz
P1.0 - P1.7
P2.0 - P2.4
Address
t AVQV
Port 0
Data OUT
t ELQV
tEHQZ
P2.7
ENABLE
MCT00049
V
Address: P1.0 - P1.7 = A0 - A7
P2.0 - P2.4 = A8 - A12
Inputs: P2.5 - P2.6, PSEN =
ALE, EA =
VSS
V IH
P0.0 - P0.7 = D0 - D7
RESET =
Data:
SS
ROM Verification Mode 1
Semiconductor Group
10-14
Device Specifications
C501
10.8 OTP Programming and Verification Characteristics for C501-1E
CC = 5 V ± 10%, VSS = 0 V, TA = 21 °C to + 27 °C
V
Parameter
Symbol
Limit Values
Unit
min.
12.5
–
max.
13.0
50
Programming supply voltage
Programming supply current
Oscillator frequency
VPP
V
IPP
mA
MHz
ns
ns
ns
ns
ns
µs
µs
µs
ns
ns
ns
µs
1 / tCLCL
tAVGL
tGHAX
tDVGL
tGHDX
tEHSH
tSHGL
tGHSL
tGLGH
tAVQV
tELQV
tEHQZ
tGHGL
4
6
Address setup to ALE/PROG low
Address hold after ALE/PROG
Data setup to ALE/PROG low
Data hold after ALE/PROG
P2.7 (ENABLE) high to VPP
VPP setup to ALE/PROG low
48 tCLCL
48 tCLCL
48 tCLCL
48 tCLCL
48 tCLCL
10
–
–
–
–
–
–
V
PP hold after ALE/PROG low
10
–
ALE/PROG width
90
110
Address to data valid
–
48 tCLCL
48 tCLCL
48 tCLCL
–
ENABLE low to data valid
Data float after ENABLE
ALE/PROG high to ALE/PROG low
–
0
10
Semiconductor Group
10-15
Device Specifications
C501
Programming
Address
Verification
Address
P1.0 - P1.7
P2.0 - P2.4
t AVQV
Port 0
Data
Data
t DVGL
t AVGL
t GHDX
t GHAX
ALE/PROG
t GHGL
t GHSL
t GLGH
t SHGL
Logic 1
EA/VPP
Logic 0
t EHSH
t ELQV
t EHQZ
P2.7
ENABLE
MCT03237
C501-1E OTP Memory Program/Read Cycle
Semiconductor Group
10-16
Device Specifications
C501
AC Inputs during testing are driven at VCC – 0.5 V for a logic ‘1’ and 0.45 V for a logic ‘0’. Timing
measurements are made at VIHmin for a logic ‘1’ and VILmax for a logic ‘0’.
AC Testing: Input, Output Waveforms
For timing purposes a port pin is no longer floating when a 100 mV change from load voltage
occurs and begins to float when a 100 mV change from the loaded VOH / VOL level occurs.
IOL / IOH ≥ ± 20 mA.
AC Testing: Float Waveforms
Semiconductor Group
10-17
Device Specifications
C501
Crystal Oscillator Mode
C
Driving from External Source
N.C.
XTAL2
XTAL2
P-LCC-44/Pin 20
P-DIP-40/Pin 18
M-QFP-44/Pin 14
P-LCC-44/Pin 20
P-DIP-40/Pin 18
M-QFP-44/Pin 14
3.5 - 40 MHz
C
External Oscillator
Signal
XTAL1
XTAL1
P-LCC-44/Pin 21
P-DIP-40/Pin 19
M-QFP-44/Pin 15
P-LCC-44/Pin 21
P-DIP-40/Pin 19
M-QFP-44/Pin 15
C = 20 pF 10 pF
MCS02452
(incl. stray capacitance)
Note : During programming and verification of the C501-1E OTP memory
a clock signal of 4-6 MHz must be applied to the device.
Recommended Oscillator Circuits
Semiconductor Group
10-18
Device Specifications
C501
10.9 Package Outlines
Plastic Package, P-DIP-40 for C501G-L / C501G-1R
(Plastic Dual in-Line Package)
P-DIP-40 Package Outlines
Sorts of Packing
Package outlines for tubes, trays etc. are contained in our
Data Book “Package Information”
Dimensions in mm
SMD = Surface Mounted Device
Semiconductor Group
10-19
Device Specifications
C501
Plastic Package, P-LCC-44 – SMD for C501G-L / C501G-1R / C501G-1E
(Plastic Leaded Chip-Carrier)
P-LCC-44 Package Outlines
Sorts of Packing
Package outlines for tubes, trays etc. are contained in our
Data Book “Package Information”
Dimensions in mm
SMD = Surface Mounted Device
Semiconductor Group
10-20
Device Specifications
C501
Plastic Package, P-MQFP-44 – SMD for C501G-L / C501G-1R
(Plastic Metric Quad Flat Package)
P-MQFP-44 Package Outlines
Sorts of Packing
Package outlines for tubes, trays etc. are contained in our
Data Book “Package Information”
Dimensions in mm
SMD = Surface Mounted Device
Semiconductor Group
10-21
Index
C501
11
Index
External bus interface . . . . . . . . . . . . . . 4-1
ALE signal . . . . . . . . . . . . . . . . . . . . . 4-4
Overlapping of data/program memory 4-4
Program memory access . . . . . . . . . . 4-3
Program/data memory timing. . . . . . . 4-2
PSEN signal. . . . . . . . . . . . . . . . . . . . 4-4
Role of P0 and P2 . . . . . . . . . . . . . . . 4-1
Note :Bold page numbers refer to the main definition
part of SFRs or SFR bits.
A
Absolute maximum ratings. . . . . . . . . . 10-1
AC . . . . . . . . . . . . . . . . . . . . . . . . . 2-3, 3-6
AC characteristics . . . . . . . . . 10-5 to 10-13
ACC . . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-6
ALE signal . . . . . . . . . . . . . . . . . . . . . . . 4-4
F
F0. . . . . . . . . . . . . . . . . . . . . . . . . . 2-3, 3-6
F1. . . . . . . . . . . . . . . . . . . . . . . . . . 2-3, 3-6
Features. . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Functional units . . . . . . . . . . . . . . . . . . . 1-1
Fundamental structure. . . . . . . . . . . . . . 2-1
B
B. . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-6
Basic CPU timing . . . . . . . . . . . . . . . . . . 2-4
Block diagram. . . . . . . . . . . . . . . . . . . . . 2-1
G
C
GATE. . . . . . . . . . . . . . . . . . . . . . 3-5, 6-17
GF0 . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 8-1
GF1 . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 8-1
C/T . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-17
C/T2 . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-24
CP/RL2. . . . . . . . . . . . . . . . . . . . . 3-5, 6-24
CPU
Accumulator . . . . . . . . . . . . . . . . . . . . 2-2
B register . . . . . . . . . . . . . . . . . . . . . . 2-3
Basic timing . . . . . . . . . . . . . . . . . . . . 2-4
Fetch/execute diagram . . . . . . . . . . . . 2-5
Functionality . . . . . . . . . . . . . . . . . . . . 2-2
Program status word. . . . . . . . . . . . . . 2-2
Stack pointer. . . . . . . . . . . . . . . . . . . . 2-3
CPU timing . . . . . . . . . . . . . . . . . . . . . . . 2-5
CY . . . . . . . . . . . . . . . . . . . . . . 2-3, 2-3, 3-6
H
I
Hardware reset . . . . . . . . . . . . . . . . . . . 5-1
Hardware reset timing . . . . . . . . . . . . . . 5-2
I/O ports. . . . . . . . . . . . . . . . . . . 6-1 to 6-12
IDLE. . . . . . . . . . . . . . . . . . . . . . . . 3-5, 8-1
Idle mode. . . . . . . . . . . . . . . . . . . . . . . . 8-2
IE . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5, 7-2
IE0 . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-4
IE1 . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-4
INT0. . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-10
INT1. . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-10
Interrupts . . . . . . . . . . . . . . . . . . 7-1 to 7-11
Block diagram . . . . . . . . . . . . . . . . . . 7-1
Enable registers . . . . . . . . . . . . . . . . . 7-2
External interrupts . . . . . . . . . . . . . . 7-10
Handling procedure . . . . . . . . . . . . . . 7-8
Priority register. . . . . . . . . . . . . . . . . . 7-6
Priority within level structure . . . . . . . 7-7
Registers . . . . . . . . . . . . . . . . . 7-2 to 7-6
Request flags . . . . . . . . . . . . . . . . . . . 7-4
Response time . . . . . . . . . . . . . . . . . 7-11
Sources and vector addresses. . . . . . 7-9
IP . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5, 7-6
IT0 . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-4
IT1 . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-4
D
DC characteristics . . . . . . . . . . 10-2 to 10-4
DCEN . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-25
Device characteristics . . . . . . 10-1 to 10-21
DPH . . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5
DPL . . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5
E
EA. . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-2
Emulation concept . . . . . . . . . . . . . . . . . 4-5
ES. . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-2
ET0. . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-2
ET1. . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-2
ET2. . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-2
EX0. . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-2
EX1. . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-2
Execution of instructions . . . . . . . . 2-4, 2-5
EXEN2 . . . . . . . . . . . . . . . . . . 3-5, 6-24, 7-3
EXF2 . . . . . . . . . . . . . . . . . . . 3-5, 6-24, 7-5
L
Logic symbol . . . . . . . . . . . . . . . . . . . . . 1-2
Semiconductor Group
11-1
Index
C501
PSEN signal. . . . . . . . . . . . . . . . . . . . . . 4-4
PSW. . . . . . . . . . . . . . . . . . . . . 2-3, 3-4, 3-6
PT0 . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-6
PT1 . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-6
PT2 . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-6
PX0 . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-6
PX1 . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-6
M
O
M0 . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-17
M1 . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-17
Memory organization . . . . . . . . . . . . . . . 3-1
Data memory . . . . . . . . . . . . . . . . . . . 3-2
General purpose registers . . . . . . . . . 3-2
Memory map. . . . . . . . . . . . . . . . . . . . 3-1
Program memory . . . . . . . . . . . . . . . . 3-2
R
RB8 . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-31
RC2H. . . . . . . . . . . . . . . . . . . 3-4, 3-5, 6-23
RC2L . . . . . . . . . . . . . . . . . . . 3-4, 3-5, 6-23
RCLK . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-24
RD . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 4-1
REN . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-31
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
RI . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-31, 7-5
RS0 . . . . . . . . . . . . . . . . . . . . . . . . 2-3, 3-6
RS1 . . . . . . . . . . . . . . . . . . . . . . . . 2-3, 3-6
RxD . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-29
OTP memory operation . . . . . . . . 9-1 to 9-4
Encryption table . . . . . . . . . . . . . . . . . 9-3
Programming configuration. . . . . . . . . 9-2
Programming modes . . . . . . . . . . . . . 9-1
Programming waveform . . . . . . . . . . . 9-2
Security bits . . . . . . . . . . . . . . . . . . . . 9-3
Verification and signature bytes . . . . . 9-4
OV . . . . . . . . . . . . . . . . . . . . . . . . . 2-3, 3-6
P
P. . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3, 3-6
P0. . . . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5
P1. . . . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5
P2. . . . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5
P3. . . . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5
Parallel I/O . . . . . . . . . . . . . . . . . 6-1 to 6-12
PCON. . . . . . . . . . . . . . . 3-4, 3-5, 6-32, 8-1
PDE . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 8-1
Pin configurations. . . . . . . . . . . . . 1-3 to 1-5
P-DIP-40 package . . . . . . . . . . . . . . . 1-4
P-LCC-44 package . . . . . . . . . . . . . . . 1-3
P-MQFP-44 package . . . . . . . . . . . . . 1-5
Pin definitions and functions. . . . 1-6 to 1-10
Ports. . . . . . . . . . . . . . . . . . . . . . 6-1 to 6-12
Alternate functions . . . . . . . . . . 6-8 to 6-9
Port loading and interfacing . . . . . . . 6-11
Port timing. . . . . . . . . . . . . . . . . . . . . 6-10
Quasi-bidirectional port structure
Output driver circuitry . . . . . . . . . . . 6-4
Port 0/2 as address/data bus . . . . . 6-7
Read-modify-write function. . . . . . . . 6-11
Power down mode . . . . . . . . . . . . . . . . . 8-3
Power saving modes . . . . . . . . . . 8-1 to 8-4
Control register . . . . . . . . . . . . . . . . . . 8-1
Idle mode . . . . . . . . . . . . . . . . . . . . . . 8-2
Power down mode . . . . . . . . . . . . . . . 8-3
State of pins . . . . . . . . . . . . . . . . . . . . 8-4
PS. . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 7-6
S
SBUF . . . . . . . . . . . . . . . . . . . 3-4, 3-5, 6-31
SCON . . . . . . . . . . . . . . 3-4, 3-5, 6-31, 7-5
Serial interface (USART) . . . . . 6-29 to 6-44
Baudrate generation. . . . . . . . . . . . . 6-32
with timer 1 . . . . . . . . . . . . . . . . . . 6-33
with timer 2 . . . . . . . . . . . . . . . . . . 6-34
Multiprocessor communication. . . . . 6-30
Operating mode 0 . . . . . . . . 6-36 to 6-38
Operating mode 1 . . . . . . . . 6-39 to 6-41
Operating mode 2 and 3 . . . 6-42 to 6-44
Registers . . . . . . . . . . . . . . . 6-30 to 6-31
SM0 . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-31
SM1 . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-31
SM2 . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-31
SMOD . . . . . . . . . . . . . . . . . . . . . 3-5, 6-32
SP . . . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5
Special function registers. . . . . . . 3-3 to 3-6
Table - address ordered. . . . . . 3-5 to 3-6
Table - functional order . . . . . . . . . . . 3-4
T
T0. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
T1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
T2CON. . . . . . . . . . . 3-4, 3-5, 6-24, 7-3, 7-5
T2MOD . . . . . . . . . . . . . . . . . 3-4, 3-5, 6-25
TB8 . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-31
TCLK . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-24
Semiconductor Group
11-2
Index
C501
TCON . . . . . . . . . . . . . . . 3-4, 3-5, 6-16, 7-4
TF0. . . . . . . . . . . . . . . . . . . . . 3-5, 6-16, 7-4
TF1. . . . . . . . . . . . . . . . . . . . . 3-5, 6-16, 7-4
TF2. . . . . . . . . . . . . . . . . . . . . 3-5, 6-24, 7-5
TH0. . . . . . . . . . . . . . . . . . . . . 3-4, 3-5, 6-15
TH1. . . . . . . . . . . . . . . . . . . . . 3-4, 3-5, 6-15
TH2. . . . . . . . . . . . . . . . . . . . . 3-4, 3-5, 6-23
TI . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-31, 7-5
Timer/counter . . . . . . . . . . . . . . . . . . . . 6-13
Timer/counter 0 and 1. . . . . . 6-14 to 6-21
Mode 0, 13-bit timer/counter . . . . . 6-18
Mode 1, 16-bit timer/counter . . . . . 6-19
Mode 2, 8-bit rel. timer/counter . . . 6-20
Mode 3, two 8-bit timer/counter. . . 6-21
Registers. . . . . . . . . . . . . . 6-15 to 6-17
Timer/counter 2. . . . . . . . . . . 6-22 to 6-28
Auto-reload mode DCEN=0 . . . . . 6-26
Auto-reload mode DCEN=1 . . . . . 6-27
Capture mode . . . . . . . . . . . . . . . . 6-28
Operating modes. . . . . . . . . . . . . . 6-22
Registers. . . . . . . . . . . . . . 6-23 to 6-25
TL0 . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5, 6-15
TL1 . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5, 6-15
TL2 . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5, 6-23
TMOD. . . . . . . . . . . . . . . . . . . 3-4, 3-5, 6-17
TR0. . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-16
TR1. . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-16
TR2. . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-24
TxD. . . . . . . . . . . . . . . . . . . . . . . . 3-5, 6-29
W
WR . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 4-1
Semiconductor Group
11-3
相关型号：
C5025.41.01
C5025, Coaxial Cable, RG11/U Type, 14 AWG Solid Copper Clad Steel, 97% Bare Copper Braid
GENERAL
C50254101
C5025, Coaxial Cable, RG11/U Type, 14 AWG Solid Copper Clad Steel, 97% Bare Copper Braid
GENERAL
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