Infineon C164SM 16-bit single-chip microcontroller Datasheet

U s e r ’ s M a n u a l , V 1. 0 , F e b . 2 00 2
C164CM/SM
16-Bit Single-Chip Microcontroller
Microcontrollers
N e v e r
s t o p
t h i n k i n g .
Edition 2002-02
Published by Infineon Technologies AG,
St.-Martin-Strasse 53,
D-81541 München, Germany
© Infineon Technologies AG 2002.
All Rights Reserved.
Attention please!
The information herein is given to describe certain components and shall not be considered as warranted
characteristics.
Terms of delivery and rights to technical change reserved.
We hereby disclaim any and all warranties, including but not limited to warranties of non-infringement, regarding
circuits, descriptions and charts stated herein.
Infineon Technologies is an approved CECC manufacturer.
Information
For further information on technology, delivery terms and conditions and prices please contact your nearest
Infineon Technologies Office in Germany or our Infineon Technologies Representatives worldwide.
Warnings
Due to technical requirements components may contain dangerous substances. For information on the types in
question please contact your nearest Infineon Technologies Office.
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approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause the failure
of that life-support device or system, or to affect the safety or effectiveness of that device or system. Life support
devices or systems are intended to be implanted in the human body, or to support and/or maintain and sustain
and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other persons may
be endangered.
U s e r ’ s M a n u a l , V 1. 0 , F e b . 2 00 2
C164CM/SM
16-Bit Single-Chip Microcontroller
Microcontrollers
N e v e r
s t o p
t h i n k i n g .
C164CM
Revision History:
V1.0, 2002-02
Previous Version:
-
Page
Subjects (major changes since last revision)
Controller Area Network (CAN): License of Robert Bosch GmbH
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C164CM/C164SM
Derivatives
Table of Contents
Page
1
1.1
1.2
1.3
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Members of the 16-bit Microcontroller Family . . . . . . . . . . . . . . . . . . . . .
Summary of Basic Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
2.1
2.2
2.2.1
2.2.2
2.3
2.4
2.5
2.6
Architectural Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Big Performance in a Small Package . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Basic CPU Concepts and Optimizations . . . . . . . . . . . . . . . . . . . . . . . . 2-3
High Instruction Bandwidth / Fast Execution . . . . . . . . . . . . . . . . . . . . 2-4
Programmable Multiple Priority Interrupt System . . . . . . . . . . . . . . . . 2-8
On-Chip System Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
On-Chip Peripheral Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
Power Management Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19
Protected Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21
3
3.1
3.2
3.3
3.4
3.5
3.6
3.6.1
3.6.2
3.6.3
Memory Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Internal ROM Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Internal RAM and SFR Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
External Memory Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
Crossing Memory Boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
Protection of the On-Chip Mask ROM . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
OTP Memory Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12
Selecting an OTP Programming Mode . . . . . . . . . . . . . . . . . . . . . . . 3-14
OTP Module Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-16
Read Protection Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19
4
4.1
4.2
4.3
4.4
4.5
Central Processing Unit (CPU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Instruction Pipelining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Particular Pipeline Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
Bit-Handling and Bit-Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10
Instruction State Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
CPU Special Function Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12
5
5.1
5.1.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
Interrupt and Trap Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Interrupt System Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
Interrupt Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
Operation of the PEC Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11
Prioritization of Interrupt and PEC Service Requests . . . . . . . . . . . . . . 5-15
Saving Status during Interrupt Service . . . . . . . . . . . . . . . . . . . . . . . . . 5-17
Interrupt Response Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-19
PEC Response Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-22
Interrupt Node Sharing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-24
External Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-25
Trap Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-31
User’s Manual
I-1
1-1
1-3
1-5
1-8
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Derivatives
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6
6.1
6.2
6.3
6.4
Clock Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
Frequency Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
Oscillator Watchdog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-9
Clock Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10
7
7.1
7.2
7.3
7.4
7.5
7.6
7.7
Parallel Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Output Driver Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
Alternate Port Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9
PORT0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11
PORT1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-16
Port 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-21
Port 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-24
Port 20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-28
8
Dedicated Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
9
9.1
9.2
9.3
9.4
9.5
9.6
9.6.1
9.6.2
External Bus Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
Single Chip Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2
External Bus Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2
Programmable Bus Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9
Controlling the External Bus Controller . . . . . . . . . . . . . . . . . . . . . . . . . 9-15
EBC Idle State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-23
The XBUS Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-24
Accessing the On-chip XBUS Peripherals . . . . . . . . . . . . . . . . . . . . . 9-25
External Accesses to XBUS Peripherals . . . . . . . . . . . . . . . . . . . . . 9-25
10
10.1
10.1.1
10.1.2
10.1.3
General Purpose Timer Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
Timer Block GPT1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
GPT1 Core Timer T3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3
GPT1 Auxiliary Timers T2 and T4 . . . . . . . . . . . . . . . . . . . . . . . . . . 10-12
Interrupt Control for GPT1 Timers . . . . . . . . . . . . . . . . . . . . . . . . . . 10-20
11
11.1
11.2
11.3
11.4
11.5
Asynchronous/Synchronous Serial Interface . . . . . . . . . . . . . . . . . . 11-1
Asynchronous Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-5
Synchronous Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-8
Hardware Error Detection Capabilities . . . . . . . . . . . . . . . . . . . . . . . . 11-10
ASC0 Baud Rate Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-11
ASC0 Interrupt Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-15
12
12.1
12.2
12.3
12.4
High-Speed Synchronous Serial Interface . . . . . . . . . . . . . . . . . . . . 12-1
Full-Duplex Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-7
Half-Duplex Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-10
Continuous Transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-11
Port Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-12
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12.5
12.6
12.7
Baud Rate Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-13
Error Detection Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-15
SSC Interrupt Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-17
13
13.1
13.2
Watchdog Timer (WDT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-1
Operation of the Watchdog Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-3
Reset Source Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-6
14
Real Time Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-1
15
15.1
15.2
15.3
15.4
Bootstrap Loader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Entering the Bootstrap Loader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loading the Startup Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exiting Bootstrap Loader Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Choosing the Baudrate for the BSL . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
16.1
16.2
16.3
16.4
16.5
16.6
16.7
Capture/Compare Unit CAPCOM2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-1
CAPCOM2 Timers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-4
CAPCOM2 Unit Timer Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-9
Capture/Compare Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-10
Capture Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-12
Compare Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-14
Capture/Compare Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-22
Interrupts for the Upper CAPCOM Channels . . . . . . . . . . . . . . . . . . . 16-23
17
17.1
17.2
17.3
17.3.1
17.4
17.5
17.6
17.6.1
17.6.2
17.7
17.8
17.9
Capture/Compare Unit CAPCOM6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-1
Output Signal Level Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-4
Edge Aligned Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-5
Center Aligned Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-7
Timing Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-8
Burst Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-10
Capture Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-11
Combined Multi-Channel Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-12
Output Signals in Multi-Channel Mode . . . . . . . . . . . . . . . . . . . . . . 17-13
Block Commutation Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-16
Trap Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-18
Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-21
The CAPCOM6 Interrupt Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-32
18
18.1
18.2
18.3
Analog/Digital Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-1
Mode Selection and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-3
Conversion Timing Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-13
A/D Converter Interrupt Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-15
19
On-Chip CAN Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-1
User’s Manual
I-3
15-1
15-2
15-5
15-5
15-6
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19.1
19.2
19.2.1
19.2.2
19.2.3
19.3
19.4
19.5
19.6
Functional Blocks of the CAN Module . . . . . . . . . . . . . . . . . . . . . . . . . . 19-2
General Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-7
CAN Interrupt Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-9
Configuration of the Bit Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-11
Mask Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-15
The Message Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-18
Controlling the CAN Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-30
Configuration Examples for Message Objects . . . . . . . . . . . . . . . . . . . 19-34
CAN Application Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-36
20
20.1
20.2
20.3
20.4
20.4.1
20.4.2
20.5
System Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-1
Reset Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-2
Status After Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-5
Application-Specific Initialization Routine . . . . . . . . . . . . . . . . . . . . . . . 20-9
System Startup Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-12
System Startup Configuration upon an External Reset . . . . . . . . . . 20-13
System Startup Configuration at Single-Chip Mode Reset . . . . . . . 20-19
System Configuration via Software . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-21
21
21.1
21.2
21.3
21.3.1
21.4
21.5
21.6
21.7
Power Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-1
Idle Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-4
Sleep Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-6
Power Down Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-7
Output Pins Status During Power Reduction Modes . . . . . . . . . . . . . 21-9
Slow Down Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-11
Flexible Peripheral Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-15
Programmable Frequency Output Signal . . . . . . . . . . . . . . . . . . . . . . 21-17
Security Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-22
22
22.1
22.2
22.3
22.4
22.5
22.6
22.7
22.8
22.9
22.10
22.11
System Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-1
Stack Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-4
Register Banking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-9
Procedure Call Entry and Exit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-9
Table Searching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-12
Floating Point Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-12
Peripheral Control and Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-13
Trap/Interrupt Entry and Exit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-13
Inseparable Instruction Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-14
Overriding the DPP Addressing Mechanism . . . . . . . . . . . . . . . . . . . . 22-14
Handling the Internal Code Memory . . . . . . . . . . . . . . . . . . . . . . . . . . 22-16
Pits, Traps, and Mines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-18
23
23.1
Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23-1
Register Description Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23-1
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Table of Contents
Page
23.2
23.3
23.4
23.5
CPU General Purpose Registers (GPRs) . . . . . . . . . . . . . . . . . . . . . . . 23-2
Registers Ordered by Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23-4
Registers Ordered by Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23-11
Special Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23-18
24
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24-1
25
Device Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25-1
26
Keyword Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26-1
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Introduction
1
Introduction
The rapidly growing area of embedded control applications is representing one of the
most time-critical operating environments for today’s microcontrollers. Complex control
algorithms have to be processed based on a large number of digital as well as analog
input signals, and the appropriate output signals must be generated within a defined
maximum response time. Embedded control applications also are often sensitive to
board space, power consumption, and overall system cost.
Embedded control applications therefore require microcontrollers, which:
• offer a high level of system integration
• eliminate the need for additional peripheral devices and the associated software
overhead
• provide system security and fail-safe mechanisms
• provide effective means to control (and reduce) the device’s power consumption
The increasing complexity of embedded control applications requires microcontrollers
for new high-end embedded control systems to possess a significant increase in CPU
performance and peripheral functionality over conventional 8-bit controllers. To achieve
this high performance goal Infineon has decided to develop its family of 16-bit CMOS
microcontrollers without the constraints of backward compatibility.
Nonetheless the architecture of the 16-bit microcontroller family pursues successful
hardware and software concepts, which have been established in Infineon’s popular
8-bit controller families.
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Introduction
About this Manual
This manual describes the functionality of a number of 16-bit microcontrollers of the
Infineon C166 Family, the C164 group. The derivatives described here offer highperformance features in an extremely compact package.
These microcontrollers provide identical functionality to a large extent, but each device
type has specific unique features as indicated here.
The descriptions in this manual cover a superset of the provided features and refer to the
following derivatives:
• C164CM-4R
• C164SM-4R
• C164CM-4E
32 KByte Program ROM, full-function CAPCOM6, CAN module
32 KByte Program ROM, full-function CAPCOM6
32 KByte Program OTP, full-function CAPCOM6, CAN module
This manual is valid for these derivatives and describes all variations of the different
available temperature ranges and packages.
For simplicity, these various device types are referred to by the collective term C164CM
throughout this manual. The complete pro-electron conforming designations are listed in
the respective data sheets.
Some sections of this manual do not refer to all of the C164CM derivatives which are
currently available or planned (such as devices with different types of on-chip memory
or peripherals). These sections contain respective notes wherever possible.
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Introduction
1.1
Members of the 16-bit Microcontroller Family
The microcontrollers in the Infineon 16-bit family have been designed to meet the high
performance requirements of real-time embedded control applications. The architecture
of this family has been optimized for high instruction throughput and minimized response
time to external stimuli (interrupts). Intelligent peripheral subsystems have been
integrated to reduce the need for CPU intervention to a minimum extent. This also
minimizes the need for communication via the external bus interface. The high flexibility
of this architecture allows to serve the diverse and varying needs of different application
areas such as automotive, industrial control, or data communications.
The core of the 16-bit family has been developed with a modular family concept in mind.
All family members execute an efficient control-optimized instruction set (additional
instructions for members of the second generation). This allows easy and quick
implementation of new family members with different internal memory sizes and
technologies, different sets of on-chip peripherals, and/or different numbers of IO pins.
The XBUS concept (internal representation of the external bus interface) provides a
straightforward path for building application-specific derivatives by integrating
application-specific peripheral modules with the standard on-chip peripherals.
As programs for embedded control applications become larger, high level languages are
favored by programmers, because high level language programs are easier to write, to
debug and to maintain. The C166 Family supports this starting with its 2nd generation.
The 80C166-type microcontrollers were the first generation of the 16-bit controller
family. These devices established the C166 architecture.
The C165-type and C167-type devices are members of the second generation of this
family. This second generation is even more powerful due to additional instructions for
HLL support, an increased address space, increased internal RAM, and highly efficient
management of various resources on the external bus.
Enhanced derivatives of this second generation provide more features such as
additional internal high-speed RAM, an integrated CAN-Module, an on-chip PLL, etc.
The design of more efficient systems may require the integration of application-specific
peripherals to boost system performance while minimizing the part count. These efforts
are supported by the XBUS, defined for the Infineon 16-bit microcontrollers (second
generation). The XBUS is an internal representation of the external bus interface which
opens and simplifies the integration of peripherals by standardizing the required
interface. One representative taking advantage of this technology is the integrated CAN
module.
The C165-type devices are reduced functionality versions of the C167 because they do
not have the A/D converter, the CAPCOM units, and the PWM module. This results in a
smaller package, reduced power consumption, and design savings.
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Introduction
The C164-type devices, the C167CS derivatives, and some of the C161-type devices
are further enhanced by a flexible power management and form the third generation of
the 16-bit controller family. This power management mechanism provides an effective
means to control the power that is consumed in a certain state of the controller and thus
minimizes the overall power consumption for a given application.
A variety of different versions is provided which offer various kinds of on-chip program
memory:
•
•
•
•
Mask-programmable ROM
Flash memory
OTP memory
ROMless without non-volatile memory.
Also there are devices with specific functional units.
The devices may be offered in different packages, temperature ranges and speed
classes.
Additional standard and application-specific derivatives are planned and are in
development.
Note: Not all derivatives will be offered in all temperature ranges, speed classes,
packages, or program memory variations.
Information about specific versions and derivatives will be made available with the
devices themselves. Contact your Infineon representative for up-to-date material.
Note: As the architecture and the basic features, such as the CPU core and built-in
peripherals, are identical for most of the currently offered versions of the C164CM,
descriptions within this manual that refer to the “C164CM” also apply to the other
variations, unless otherwise noted.
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Introduction
1.2
Summary of Basic Features
The C164CM devices are very compact members of the Infineon family of full featured
16-bit single-chip CMOS microcontrollers. The C164CM combines high CPU
performance (up to 12.5 million instructions per second) with high peripheral functionality
and provides a means for power reduction.
Several key features contribute to the high performance of the C164CM (the indicated
timings refer to a CPU clock of 25 MHz).
High Performance 16-bit CPU with Four-Stage Pipeline
•
•
•
•
•
•
•
80 ns minimum instruction cycle time, with most instructions executed in 1 cycle
400 ns multiplication (16-bit × 16-bit), 800 ns division (32-bit / 16-bit)
Multiple high bandwidth internal data buses
Register-based design with multiple, variable register banks
Single-cycle context switching support
16 MBytes of linear address space for code and data (Von Neumann architecture)
System stack cache support with automatic stack overflow/underflow detection
Control Oriented Instruction Set with High Efficiency
• Bit, byte, and word data types
• Flexible and efficient addressing modes for high code density
• Enhanced boolean bit manipulation with direct addressability of 6 Kbits
for peripheral control and user-defined flags
• Hardware traps to identify exception conditions during runtime
• HLL support for semaphore operations and efficient data access
Power Management Features
•
•
•
•
Programmable system slowdown via Slow Down Divider (SDD)
Flexible management of peripherals, can be individually disabled
Sleep-mode supports wake-up via external interrupts
Programmable frequency output
Integrated On-Chip Memory
• 2 KBytes Internal RAM (IRAM) for variables, register banks, system stack, and code
• 32 KBytes on-chip Program memory (OTP or Mask ROM, not for ROMless devices)
External Bus Interface
• Multiplexed or demultiplexed bus configurations
• 8-bit or 16-bit data bus
• Bus cycle characteristics selectable for five programmable address areas
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Introduction
16-Priority-Level Interrupt System
• 32 interrupt nodes with separate interrupt vectors
• 240 ns typical interrupt latency (400 ns maximum)
in case of internal program execution
• Fast external interrupts
8-Channel Peripheral Event Controller (PEC)
• Interrupt driven single cycle data transfer
• Transfer count option
(standard CPU interrupt after programmable number of PEC transfers)
• Overhead from saving and restoring system state for interrupt requests eliminated
Intelligent On-Chip Peripheral Subsystems
• 8-channel 10-bit A/D Converter with programmable conversion time
(7.8 µs minimum), auto scan modes, channel injection mode
• Two Capture/Compare Units with independent time bases,
very flexible PWM unit/event recording unit with different operating modes
• Multifunctional General Purpose Timer Unit with three 16-bit timers/counters,
maximum resolution fCPU/8
• Asynchronous/Synchronous Serial Channel (USART)
with baud rate generator, parity, framing, and overrun error detection
• High Speed Synchronous Serial Channel
programmable data length and shift direction
• Controller Area Network (CAN) Module, Rev. 2.0B active, with 15 Message Objects,
Full-CAN/Basic-CAN
• Real Time Clock
• Watchdog Timer with programmable time intervals
• Bootstrap Loader for flexible system initialization
50 IO Lines with Individual Bit Addressability
• Tri-stated in input mode
• Push/pull or open drain output mode
• Programmable port driver control
Various Temperature Ranges
• 0 to +70 °C
• -40 to +85 °C
• -40 to +125 °C
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Introduction
Infineon CMOS Process
• Low power CMOS technology enables power saving Idle, Sleep, and Power Down
modes with flexible power management.
64-Pin Plastic Metric Thin Quad Flat Pack (TQFP) Package
• P-TQFP, 10 × 10 mm body, 0.5 mm (19.7 mil) lead spacing,
surface mount technology
Complete Development Support
For the development tool support of its microcontrollers, Infineon follows a clear third
party concept. Currently around 120 tool suppliers world-wide, ranging from local niche
manufacturers to multinational companies with broad product portfolios, offer powerful
development tools for the Infineon C500 and C166 microcontroller families,
guaranteeing a remarkable variety of price-performance classes as well as early
availability of high quality key tools such as compilers, assemblers, simulators,
debuggers or in-circuit emulators.
Infineon incorporates its strategic tool partners very early into the product development
process, making sure embedded system developers get reliable, well-tuned tool
solutions, which help them unleash the power of Infineon microcontrollers in the most
effective way and with the shortest possible learning curve.
The tool environment for the Infineon 16-bit microcontrollers includes the following tools:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Compilers (C, MODULA2, FORTH)
Macro-assemblers, linkers, locators, library managers, format-converters
Architectural simulators
HLL debuggers
Real-time operating systems
VHDL chip models
In-circuit emulators (based on bondout or standard chips)
Plug-in emulators
Emulation and clip-over adapters, production sockets
Logic analyzer disassemblers
Starter kits
Evaluation boards with monitor programs
Industrial boards (also for CAN, FUZZY, PROFIBUS, FORTH applications)
Network driver software (CAN, PROFIBUS)
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Introduction
1.3
Abbreviations
The following acronyms and terms are used within this document:
ADC
Analog Digital Converter
ALE
Address Latch Enable
ALU
Arithmetic and Logic Unit
ASC
Asynchronous/synchronous Serial Controller
CAN
Controller Area Network (License Bosch)
CAPCOM CAPture and COMpare unit
CISC
Complex Instruction Set Computing
CMOS
Complementary Metal Oxide Silicon
CPU
Central Processing Unit
EBC
External Bus Controller
ESFR
Extended Special Function Register
Flash
Non-volatile memory that may be electrically erased
GPR
General Purpose Register
GPT
General Purpose Timer unit
HLL
High Level Language
IIC
Inter Integrated Circuit (Bus)
IO
Input/Output
OTP
One-Time Programmable memory
PEC
Peripheral Event Controller
PLA
Programmable Logic Array
PLL
Phase Locked Loop
PWM
Pulse Width Modulation
RAM
Random Access Memory
RISC
Reduced Instruction Set Computing
ROM
Read Only Memory
RTC
Real Time Clock
SDD
Slow Down Divider
SFR
Special Function Register
SSC
Synchronous Serial Controller
XBUS
Internal representation of the External Bus
XRAM
On-chip extension RAM
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Architectural Overview
2
Architectural Overview
The architecture of the C164CM core combines the advantages of both RISC and CISC
processors in a very well-balanced way. The C164CM integrates this powerful CPU core
with a set of powerful peripheral units into one chip and connects them very efficiently.
This combination of features results in a high performance microcontroller, which is the
right choice not only for today’s applications, but also for future engineering challenges.
One of the four buses used concurrently on the C164CM is the XBUS, an internal
representation of the external bus interface. This bus provides a standardized method
for integrating additional application-specific peripherals into derivatives of the standard
C164CM.
16
Data
ROM / OTP
32 KByte
32
16
CPU
Instr. / Data
Data
Dual Port
C166-Core
ProgMem
16
IRAM
Internal
RAM
2 KByte
Osc / PLL
PEC
XTAL
External Instr. / Data
Interrupt Controller 16-Level
Priority
RTC
WDT
6
Port 20
EBC
XBUS Control
External Bus
Control
Port 0
16
Interrupt Bus
Peripheral Data Bus
16
ADC
ASC0
SSC
10-Bit
8
Channels
(USART)
(SPI)
GPT1
CCOM2 CCOM6
T2
T7
T12
T3
T8
T13
T4
BRGen
Port 8
CAN
Rev 2.0B active
On-Chip XBUS (16-Bit Demux)
16
4
BRGen
Port 5
Port 1
16
8
MCB04323_4cm
Figure 2-1
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Architectural Overview
2.1
Big Performance in a Small Package
It seemed not feasible to put a 16-bit microcontroller into a tiny package such as the
TQFP-64 when the Infineon C166 Family was created. In the meantime, however,
several improvements were added to the architecture which, when combined, allow
high-performance operation of a 16-bit microcontroller in a 64-pin package.
The combination of the following features was the basis for the realization of a compact
microcontroller such as the C164CM:
• Single Chip Mode without reset configuration via PORT0 removes the need for
configuration devices (pull-ups, pull-downs) on the PORT0 pins, so now they can be
effectively used for peripherals or IO functions.
• Serial Interfaces on PORT0 allow the removal of Port 3, while retaining the
peripherals’ functionality. This reduces the pin-count.
• Modified multiplexed bus mode with 8-bit data and 11-bit address enables the
concurrent operation of serial interfaces (see above) and the external bus interface.
• CAN interface on Port 8 allows the removal of Port 4. This reduces the pin-count.
• Introduction of Port 20 adds IO functionality to several formerly dedicated pins which
can now also be used by single-chip-mode applications.
• On-chip Program Memory (OTP, ROM) supports development and volume
production of single-chip applications.
Cutting features only where required, moving vital functions to the remaining pins,
adding new features such as configuration via software, maintaining the basic
architecture (on-chip PLL, 16-bit CPU, PEC, interrupt controller, memory concept),
keeping powerful industry-standard peripheral modules such as CAPCOM6 and CAN,
resulted in a compact member of Infineon’s C166 Family of 16-bit microcontrollers which
fits to a board space of merely 1.44 cm2 (0.223 inch2) at a package body size of just
1.0 cm2 (0.155 inch2).
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Architectural Overview
2.2
Basic CPU Concepts and Optimizations
The main core of the CPU consists of a four-stage instruction pipeline, a 16-bit Arithmetic
and Logic Unit (ALU) and dedicated Special Function Registers (SFRs). Additional
hardware is provided for a separate multiply and divide unit, a bit-mask generator, and
a barrel shifter.
Figure 2-2
CPU Block Diagram
To meet the demand for greater performance and flexibility, a number of functional
blocks of the CPU have been optimized. These blocks are controlled by signals from the
instruction decode logic. Optimizations of the functional blocks are summarized below
and described in detail in the following sections:
1. High Instruction Bandwidth / Fast Execution
2. High Function 8-bit and 16-bit Arithmetic and Logic Unit
3. Extended Bit Processing and Peripheral Control
4. High Performance Branch-, Call-, and Loop Processing
5. Consistent and Optimized Instruction Formats
6. Programmable Multiple Priority Interrupt Structure
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Architectural Overview
2.2.1
High Instruction Bandwidth / Fast Execution
Based on the hardware provisions, most of the C164CM’s instructions can be executed
in just one machine cycle, which requires two CPU clock cycles (2 × 1/fCPU = 4 TCL). For
example, shift and rotate instructions are always processed within one machine cycle,
independent of the number of bits to be shifted.
Branch-, multiply- and divide instructions normally take more than one machine cycle.
These instructions, however, have also been optimized. For example, branch
instructions require an additional machine cycle only when a branch is taken.
Subsequent branches taken in loops require no additional machine cycles at all, due to
the Jump Cache feature.
A 32-bit / 16-bit division requires 20 CPU clock cycles, a 16-bit × 16-bit multiplication
requires 10 CPU clock cycles.
The instruction cycle time has been dramatically reduced through the use of instruction
pipelining. This technique allows the core CPU to process portions of multiple sequential
instruction stages in parallel. The following four-stage pipeline provides the optimum
balancing for the CPU core:
FETCH: In this stage, an instruction is fetched from the internal ROM or RAM or from the
external memory, based on the current IP value.
DECODE: In this stage, the previously fetched instruction is decoded and the required
operands are fetched.
EXECUTE: In this stage, the specified operation is performed on the previously fetched
operands.
WRITE BACK: In this stage, the result is written to the specified location.
If this technique were not used, each instruction would require four machine cycles. This
increased performance allows a greater number of tasks and interrupts to be processed.
Instruction Decoder
Instruction decoding is generated primarily from Programmable Logic Array (PLA)
outputs based on the selected opcode. No microcode is used and each pipeline stage
receives control signals staged in control registers from the decode stage PLAs. Pipeline
holds are primarily caused by wait states for external memory accesses and cause the
holding of signals in the control registers. Multiple-cycle instructions are performed
through instruction injection and simple internal state machines which modify required
control signals.
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Architectural Overview
High Function 8-bit and 16-bit Arithmetic and Logic Unit
All standard arithmetic and logical operations are performed in a 16-bit ALU. Additionally,
for byte operations, signals are provided from bits 6 and 7 of the ALU result to set the
condition flags correctly. Multiple precision arithmetic is provided through a ‘CARRY-IN’
signal to the ALU from previously calculated portions of the desired operation.
Most internal execution blocks have been optimized to perform operations on either 8-bit
or 16-bit quantities. Once the pipeline has been filled, one instruction is completed per
machine cycle, except for multiply and divide. An advanced Booth algorithm has been
incorporated to allow four bits to be multiplied and two bits to be divided per machine
cycle. Thus, these operations use two coupled 16-bit registers, MDL and MDH, and
require four and nine machine cycles, respectively, to perform a 16-bit by 16-bit (or 32-bit
by 16-bit) calculation plus one machine cycle to setup and adjust the operands and the
result. Even these longer multiply and divide instructions can be interrupted during their
execution to allow for very fast interrupt response. Instructions have been provided as
well to allow byte packing in memory while providing sign extension of bytes for word
wide arithmetic operations. The internal bus structure also allows transfers of bytes or
words to or from peripherals based on the peripheral requirements.
A set of consistent flags is updated automatically in the PSW after each arithmetic,
logical, shift, or movement operation. These flags allow branching on specific conditions.
Support for both signed and unsigned arithmetic is provided through user-specifiable
branch tests. These flags are also preserved automatically by the CPU upon entry into
an interrupt or trap routine.
All targets for branch calculations are also computed in the central ALU.
A 16-bit barrel shifter provides multiple bit shifts in a single cycle. Rotates and arithmetic
shifts are also supported.
Extended Bit Processing and Peripheral Control
A large number of instructions has been dedicated to bit processing. These instructions
provide efficient control and testing of peripherals while enhancing data manipulation.
Unlike other microcontrollers, these instructions provide direct access to two operands
in the bit-addressable space without requiring them to be moved into temporary flags.
The same logical instructions available for words and bytes are also supported for bits.
This allows the user to compare and modify a control bit for a peripheral in one
instruction. Multiple bit shift instructions have been included to avoid long instruction
streams of single bit shift operations. These instructions are also performed in a single
machine cycle.
Bit field instructions have been provided as well to allow the modification of multiple bits
from one operand in a single instruction.
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Architectural Overview
High Performance Branch-, Call-, and Loop Processing
Due to the high percentage of branching in controller applications, branch instructions
have been optimized to require one extra machine cycle only when a branch is taken.
This is implemented by precalculating the target address while decoding the instruction.
To decrease loop execution overhead, three enhancements have been provided:
• Single cycle branch execution after the first iteration of a loop:
The first solution provides that only one machine cycle is lost during the execution of
the entire loop. In loops which fall through upon completion, no machine cycles are
lost when exiting the loop. No special instructions are required to perform loops, and
loops are automatically detected during execution of branch instructions.
• Detection of the end of a table:
The second loop enhancement avoids the use of two compare instructions embedded
in loops. One simply places the lowest negative number at the end of the specific table
and specifies branching if neither its value nor the compared value have been found.
Otherwise, the loop is terminated if either condition has been met. The terminating
condition can then be tested.
• Compare and Increment or Decrement instructions:
The third loop enhancement provides a more flexible solution than the Decrement and
Skip on Zero instruction found in other microcontrollers. The use of Compare and
Increment or Decrement instructions enables the user to make comparisons to any
value. This allows loop counters to cover any range and is particularly advantageous
in table searching.
The system state information is saved automatically on the internal system stack, thus
avoiding the use of instructions to preserve state upon entry and exit of interrupt or trap
routines. Call instructions push the value of the IP on the system stack, and require the
same execution time as branch instructions. Additionally, instructions have been
provided to support indirect branch and call instructions. This feature supports
implementation of multiple CASE statement branching in assembler macros and high
level languages.
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Architectural Overview
Consistent and Optimized Instruction Formats
To obtain optimum performance in a pipelined design, an instruction set has been
designed which incorporates concepts from Reduced Instruction Set Computing (RISC).
These concepts primarily allow fast decoding of the instructions and operands while
reducing pipeline holds. These concepts, however, do not preclude the use of complex
instructions required by microcontroller users. The instruction set was designed to meet
the following goals:
• Provide powerful instructions for frequently-performed operations which traditionally
have required sequences of instructions. Avoid transfer into and out of temporary
registers such as accumulators and carry bits. Perform tasks in parallel such as saving
state upon entry into interrupt routines or subroutines.
• Avoid complex encoding schemes by placing operands in consistent fields for each
instruction and avoid complex addressing modes which are not frequently used.
Consequently, the instruction decode time decreases and the development of
compilers and assemblers is simplified.
• Provide most frequently used instructions with one-word instruction formats. All other
instructions use two-word formats. This allows all instructions to be placed on word
boundaries: this alleviates the need for complex alignment hardware. It also has the
benefit of increasing the range for relative branching instructions.
The high performance of the CPU-hardware can be utilized efficiently by a programmer
by means of the highly functional C164CM instruction set which includes the following
instruction classes:
•
•
•
•
•
•
•
•
•
•
•
•
Arithmetic Instructions
Logical Instructions
Boolean Bit Manipulation Instructions
Compare and Loop Control Instructions
Shift and Rotate Instructions
Prioritize Instruction
Data Movement Instructions
System Stack Instructions
Jump and Call Instructions
Return Instructions
System Control Instructions
Miscellaneous Instructions
Possible operand types are bits, bytes and words. Specific instructions support the
conversion (extension) of bytes to words. Various direct, indirect, and immediate
addressing modes are provided to specify the required operands.
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Architectural Overview
2.2.2
Programmable Multiple Priority Interrupt System
The following enhancements within the C164CM allow processing of a large number of
interrupt sources:
• Peripheral Event Controller (PEC): This processor is used to off-load many interrupt
requests from the CPU. It avoids the overhead of entering and exiting interrupt or trap
routines by performing single-cycle interrupt-driven byte or word data transfers
between any two locations in segment 0 with an optional increment of either the PEC
source or the destination pointer. Only one cycle is ‘stolen’ from the current CPU
activity to perform a PEC service.
• Multiple Priority Interrupt Controller: This controller allows all interrupts to be assigned
any specified priority. Interrupts may also be grouped, which enables the user to
prevent similar priority tasks from interrupting each other. For each of the possible
interrupt sources, there is a separate control register which contains an interrupt
request flag, an interrupt enable flag, and an interrupt priority bitfield. After being
accepted by the CPU, an interrupt service can be interrupted only by a higher
prioritized service request. For standard interrupt processing, each of the possible
interrupt sources has a dedicated vector location.
• Multiple Register Banks: This feature allows the user to specify up to sixteen general
purpose registers located anywhere in the internal RAM. A single one-machine-cycle
instruction allows register banks to switch from one task to another.
• Interruptible Multiple Cycle Instructions: Reduced interrupt latency is provided by
allowing multiple-cycle instructions (multiply, divide) to be interruptible.
The C164CM is capable of reacting very quickly to non-deterministic events because its
interrupt response time is within a very narrow range of only 5 to 10 CPU clock cycles
(in the case of internal program execution). Its fast external interrupt inputs are sampled
every CPU clock cycle and allow even very short external signals to be recognized.
The C164CM also provides an excellent mechanism to identify and process exceptions
or error conditions that arise during run-time, so called ‘Hardware Traps’. A hardware
trap causes an immediate non-maskable system reaction which is similar to a standard
interrupt service (branching to a dedicated vector table location). The occurrence of a
hardware trap is additionally signified by an individual bit in the trap flag register (TFR).
Unless another, higher prioritized, trap service is in progress, a hardware trap will
interrupt any current program execution. In turn, a hardware trap service can normally
not be interrupted by a standard or PEC interrupt.
Software interrupts are supported by means of the ‘TRAP’ instruction in combination with
an individual trap (interrupt) number.
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2.3
On-Chip System Resources
The C164CM controllers provide a number of powerful system resources designed
around the CPU. The combination of CPU and these resources results in the high
performance of the members of this controller family.
Peripheral Event Controller (PEC) and Interrupt Control
The Peripheral Event Controller enables response to an interrupt request with a single
data transfer (word or byte) which consumes only one instruction cycle and does not
require saving and restoring the machine status. Each interrupt source is prioritized for
every machine cycle in the interrupt control block. If PEC service is selected, a PEC
transfer is started. If CPU interrupt service is requested, the current CPU priority level
stored in the PSW register is tested to determine whether a higher priority interrupt is
currently being serviced. When an interrupt is acknowledged, the current state of the
machine is saved on the internal system stack and the CPU branches to the system
specific vector for the peripheral.
The PEC contains a set of SFRs which store the count value and control bits for eight
data transfer channels. In addition, the PEC uses a dedicated area of RAM which
contains the source and destination addresses. The PEC is controlled in a manner
similar to any other peripheral: through SFRs containing the desired configuration of
each channel.
An individual PEC transfer counter is implicitly decremented for each PEC service
except in the continuous transfer mode. When this counter reaches zero, a standard
interrupt is performed to the vector location related to the corresponding source. PEC
services are very well suited, for example, to moving register contents to/from a memory
table. The C164CM has eight PEC channels, each of which offers such fast interruptdriven data transfer capabilities.
Memory Areas
The memory space of the C164CM is configured in a Von Neumann architecture. This
means that code memory, data memory, registers, and IO ports are organized within the
same linear address space which covers up to 16 MBytes. The entire memory space can
be accessed bytewise or wordwise. Particular portions of the on-chip memory have been
made directly bit addressable as well.
2 KBytes of 16-bit wide Internal RAM provide fast access to General Purpose
Registers (GPRs), user data (variables), and system stack. The internal RAM may also
be used for code. A unique decoding scheme provides flexible user register banks in the
internal memory while optimizing the remaining RAM for user data.
The CPU has an actual register context of up to 16 wordwide and/or bytewide GPRs at
its disposal, which are physically located within the on-chip RAM area. A Context Pointer
(CP) register determines the base address of the active register bank to be accessed by
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the CPU at a time. The number of register banks is restricted only by the available
internal RAM space. For easy parameter passing, a register bank may overlap other
register banks.
A system stack of up to 1024 words is provided as storage for temporary data. The
system stack is also located within the on-chip RAM area and it is accessed by the CPU
via the Stack Pointer (SP) register. Two separate SFRs, STKOV and STKUN, are
implicitly compared against the stack pointer value upon each stack access for the
detection of a stack overflow or underflow.
Hardware detection of the selected memory space is placed at the internal memory
decoders and allows the user to specify any address directly or indirectly and obtain the
desired data without using temporary registers or special instructions.
For Special Function Registers 1024 Bytes of the address space are reserved. The
standard Special Function Register area (SFR) uses 512 bytes, while the Extended
Special Function Register area (ESFR) uses the other 512 bytes. (E)SFRs are wordwide
registers which are used for controlling and monitoring functions of the different on-chip
units. Unused (E)SFR addresses are reserved for future members of the C166
microcontroller family with enhanced functionality.
Optional on-chip OTP or ROM memory provides both code and constant data storage.
This memory area is connected to the CPU via a 32-bit-wide bus. Thus, an entire doubleword instruction can be fetched in only one machine cycle. The ROM is mask
programmed at the factory while the OTP memory can also be programmed within the
application. Program execution from on-chip program memory is the fastest of all
possible alternatives.
The type of the on-chip program memory (OTP/ROM/none) depends on the chosen
derivative.
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External Bus Interface
To meet the needs of designs where more memory is required than is provided on chip,
up to 64 KBytes of external RAM and/or ROM can be connected to the C164CM
microcontroller via its external bus interface. The integrated External Bus Controller
(EBC) allows very flexible access to external memory and/or peripheral resources. For
up to five address areas the bus mode (multiplexed / demultiplexed), the data bus width
(8-bit/16-bit) and even the length of a bus cycle (waitstates, signal delays) can be
selected independently. This allows access to a variety of memory and peripheral
components directly and with maximum efficiency. If the device does not run in Single
Chip Mode, where no external memory is required, the EBC can control external
accesses in one of the following external access modes:
•
•
•
•
16-bit Addresses, 16-bit Data, Demultiplexed
16-bit Addresses, 8-bit Data, Demultiplexed
16-bit Addresses, 16-bit Data, Multiplexed
11-bit Addresses, 8-bit Data, Multiplexed
The demultiplexed bus modes use PORT1 for addresses and PORT0 for data input/
output. The multiplexed bus modes use PORT0 for both addresses and data input/
output.
Important timing characteristics of the external bus interface (waitstates, ALE length, and
Read/Write Delay) have been made programmable to allow the user select a wide range
of different types of memories and/or peripherals.
The on-chip XBUS is an internal representation of the external bus. It allows access to
integrated application-specific peripherals/modules in the same way as external
components. It provides a defined interface for these customized peripherals. The onchip CAN-Module is an example for these X-Peripherals.
Even though the C164CM supports all the bus modes described above, many
applications will use it in Single-Chip mode. Due to the very compact package many
alternate I/O signals use PORT0 and PORT1, so utilizing the full bus interface conflicts
with a number of peripheral functions.
A very good compromise is 8-bit multiplexed mode, where only 11 pins of PORT0 are
occupied by the bus interface. This allows control of external peripherals while providing
most I/O functions at the same time.
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2.4
On-Chip Peripheral Blocks
The C166 Family clearly separates peripherals from the core. This structure permits the
maximum number of operations to be performed in parallel and allows peripherals to be
added or deleted from family members without modifications to the core. Each functional
block processes data independently and communicates information over common
buses. Peripherals are controlled by data written to the respective Special Function
Registers (SFRs). These SFRs are located within either the standard SFR area
(00’FE00H … 00’FFFFH) or within the extended ESFR area (00’F000H … 00’F1FFH).
These built-in peripherals either allow the CPU to interface with the external world or
provide functions on-chip that otherwise would need to be added externally in the
respective system.
The C164CM generic peripherals are:
•
•
•
•
•
•
•
A General Purpose Timer Block (GPT1)
Two Serial Interfaces (ASC0 and SSC)
A Watchdog Timer
Two Capture / Compare units (CAPCOM2 and CAPCOM6)
A 10-bit Analog / Digital Converter
A Real Time Clock
Five I/O ports with a total of 50 I/O lines
Each peripheral also contains a set of Special Function Registers (SFRs) which control
the functionality of the peripheral and temporarily store intermediate data results. Each
peripheral has an associated set of status flags. Individually selected clock signals are
generated for each peripheral from binary multiples of the CPU clock.
Peripheral Interfaces
The on-chip peripherals generally have two different types of interfaces: an interface to
the CPU and an interface to external hardware. Communication between the CPU and
peripherals is performed through Special Function Registers (SFRs) and interrupts. The
SFRs serve as control/status and data registers for the peripherals. Interrupt requests
are generated by the peripherals based on specific events which occur during their
operation, such as operation complete, error, etc.
To interface with external hardware, specific pins of the parallel ports are used, when an
input or output function has been selected for a peripheral. During this time, the port pins
are controlled either by the peripheral (when used as outputs) or by the external
hardware which controls the peripheral (when used as inputs). This is called the
‘alternate (input or output) function’ of a port pin, in contrast to its function as a general
purpose I/O pin.
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Peripheral Timing
Internal operation of the CPU and peripherals is based on the CPU clock (fCPU). The onchip oscillator derives the CPU clock from the crystal or from the external clock signal.
The clock signal gated to the peripherals is independent from the clock signal that feeds
the CPU. During Idle mode, the CPU’s clock is stopped while the peripherals continue
their operation. Peripheral SFRs may be accessed by the CPU once per state. When an
SFR is written to by software in the same state where it is also to be modified by the
peripheral, the software write operation has priority. Further details on peripheral timing
are included in the specific sections describing each peripheral.
Programming Hints
Access to SFRs
All SFRs reside in data page 3 of the memory space. The following addressing
mechanisms allow access to the SFRs:
• Indirect or direct addressing with 16-bit (mem) addresses must guarantee that the
used data page pointer (DPP0 … DPP3) selects data page 3.
• Accesses via the Peripheral Event Controller (PEC) use the SRCPx and DSTPx
pointers instead of the data page pointers.
• Short 8-bit (reg) addresses to the standard SFR area do not use the data page
pointers but directly access the registers within this 512-Byte area.
• Short 8-bit (reg) addresses to the extended ESFR area require switching to the
512-Byte Extended SFR area. This is done via the EXTension instructions EXTR,
EXTP(R), EXTS(R).
Byte write operations to wordwide SFRs via indirect or direct 16-bit (mem) addressing
or byte transfers via the PEC force zeros in the non-addressed byte. Byte write
operations via short 8-bit (reg) addressing can access only the low byte of an SFR and
force zeros in the high byte. It is therefore recommended, to use the bit field instructions
(BFLDL and BFLDH) to write to any number of bits in either byte of an SFR without
disturbing the non-addressed byte and the unselected bits.
Reserved Bits
Some of the bits which are contained in the C164CM’s SFRs are marked as ‘Reserved’.
User software should never write ‘1’s to reserved bits. These bits are currently not
implemented and may be used in future products to invoke new functions. In that case,
the active state for those new functions will be ‘1’, and the inactive state will be ‘0’.
Therefore writing only ‘0’s to reserved locations allows portability of the current software
to future devices. After read accesses, reserved bits should be ignored or masked out.
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Serial Channels
Serial communication with other microcontrollers, processors, terminals, or external
peripheral components is provided by two serial interfaces with different functionality: an
Asynchronous/Synchronous Serial Channel (ASC0) and a High-Speed Synchronous
Serial Channel (SSC).
The ASC0 is upward compatible with the serial ports of the Infineon 8-bit microcontroller
families and supports full-duplex asynchronous communication at up to 780 kbit/s and
half-duplex synchronous communication at up to 3.1 Mbit/s @ 25 MHz CPU clock.
A dedicated baud rate generator allows all standard baud rates to be set up without
oscillator tuning. Four separate interrupt vectors are provided for transmission,
reception, and error handling. In asynchronous mode, 8- or 9-bit data frames are
transmitted or received, preceded by a start bit and terminated by one or two stop bits.
For multiprocessor communication, a mechanism has been included to distinguish
address bytes from data bytes (8-bit data plus wake-up bit mode). In synchronous mode,
the ASC0 transmits or receives bytes (8 bits) synchronously to a shift clock which is
generated by the ASC0. The ASC0 always shifts the Least Significant Bit (LSB) first. A
loop back option is available for testing purposes.
Optional hardware error detection capabilities have been included to increase the
reliability of data transfers. A parity bit can be generated automatically on transmission
or can be checked on reception. Framing error detection allows data frames with missing
stop bits to be recognized. An overrun error will be generated, if the last character
received has not been read out of the receive buffer register at the time that reception of
a new character is complete.
The SSC supports full-duplex synchronous communication at up to 6.25 Mbit/s @
25 MHz CPU clock. It may be configured so that it interfaces with serially linked
peripheral components. A dedicated baud rate generator allows set up of all standard
baud rates without oscillator tuning. Three separate interrupt vectors are provided for
transmission, reception, and error handling.
The SSC transmits or receives characters of 2 … 16 bits length synchronously to a shift
clock which can be generated by the SSC (master mode) or by an external master (slave
mode). The SSC can start shifting with the LSB or with the Most Significant Bit (MSB)
and allows selection of shifting and latching clock edges as well as the clock polarity.
A number of optional hardware error detection capabilities has been included to increase
the reliability of data transfers. Transmit and receive error supervise the correct handling
of the data buffer. Phase and baudrate error detect incorrect serial data.
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On-Chip CAN Module
The integrated CAN Module handles the completely autonomous transmission and
reception of CAN frames in accordance with the CAN specification V2.0 part B (active),
i.e. the on-chip CAN Module can receive and transmit standard frames with 11-bit
identifiers as well as extended frames with 29-bit identifiers.
The module provides Full CAN functionality on up to 15 message objects. Message
object 15 may be configured for Basic CAN functionality. Both modes provide separate
masks for acceptance filtering which allows acceptance of a number of identifiers in Full
CAN mode and also allows a number of identifiers in Basic CAN mode to be disregarded.
All message objects can be updated independently from the other objects and are
equipped for the maximum message length of 8 bytes.
The bit timing is derived from the CPU clock and is programmable up to a data rate of
1 Mbit/s. The CAN Module uses two pins (configurable) to interface to a bus transceiver.
Parallel Ports
The C164CM provides up to 50 I/O lines which are organized into four input/output ports
and one input port. All port lines are bit-addressable, and all input/output lines are
individually programmable (bit-wise) as inputs or outputs via direction registers. The I/O
ports are true bidirectional ports which are switched to high impedance state when
configured as inputs. The output drivers of one I/O port can be configured (pin by pin) for
push/pull operation or open-drain operation via a control register. During the internal
reset, all port pins are configured as inputs.
All port lines have programmable alternate input or output functions associated with
them. PORT0 and PORT1 may be used as address and data lines when accessing
external memory. PORT0 pins are also used for the standard serial interfaces ASC0 and
SSC. PORT1 provides input and output signals for the CAPCOM units. Port 5 is used for
timer control signals and for the analog inputs to the A/D Converter. Port 8 provides
inputs/outputs for the CAPCOM2 unit and for the CAN interface. Port 20 includes control
signals of the external bus interface, the RSTOUT signal, and the system clock output
(CLKOUT/FOUT). All port lines not used for these alternate functions may be used as
general purpose I/O lines.
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A/D Converter
For analog signal measurement, a 10-bit Analog/Digital (A/D) Converter with eight
multiplexed input channels and a sample and hold circuit has been integrated on-chip. It
uses the method of successive approximation. The sample time (for loading the
capacitors) and the conversion time are programmable and can so be adjusted to the
external circuitry.
Overrun error detection/protection is provided for the conversion result register
(ADDAT): either an interrupt request will be generated when the result of a previous
conversion has not been read from the result register at the time the next conversion is
complete, or the next conversion is suspended in such a case until the previous result
has been read.
For applications which require fewer analog input channels, the remaining channel
inputs can be used as digital input port pins.
The A/D Converter of the C164CM supports four different conversion modes. In the
standard Single Channel conversion mode, the analog level on a specified channel is
sampled once and converted to a digital result. In the Single Channel Continuous mode,
the analog level on a specified channel is repeatedly sampled and converted without
software intervention. In the Auto Scan mode, the analog levels on a prespecified
number of channels are sequentially sampled and converted. In the Auto Scan
Continuous mode, the prespecified channels are repeatedly sampled and converted. In
addition, the conversion of a specific channel can be inserted (injected) into a running
sequence without disturbing this sequence. This is called Channel Injection Mode.
The Peripheral Event Controller (PEC) may be used to automatically store the
conversion results into a table in memory for later evaluation, without requiring the
overhead of entering and exiting interrupt routines for each data transfer.
Real Time Clock
The C164CM contains a Real Time Clock (RTC) which serves different purposes:
• System clock to determine the current time and date,
even during idle mode and power down mode (optionally).
• Cyclic time based interrupt
(for example: to provide a system time tick independent of the CPU frequency without
loading the general purpose timers, or to wake up regularly from idle mode).
• 48-bit timer for long term measurements
(the maximum usable timespan is more than 100 years).
The RTC module consists of a chain of three divider blocks, a fixed 8:1 divider, the
reloadable 16-bit timer T14, and the 32-bit RTC timer (accessible via registers RTCH
and RTCL). Both timers count upwards.
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General Purpose Timer (GPT) Unit
The GPT1 unit utilizes a very flexible multifunctional timer/counter structure which may
be used for many different time related tasks such as event timing and counting, pulse
width and duty cycle measurements, pulse generation, or pulse multiplication.
Each timer may operate independently in a number of different modes, or may be
concatenated with another timer of the same module.
Each timer can be configured individually for one of four basic modes of operation:
Timer, Gated Timer, Counter Mode, and Incremental Interface Mode. In Timer Mode, the
input clock for a timer is derived from the internal CPU clock divided by a programmable
prescaler, while Counter Mode allows a timer to be clocked in reference to external
events (via TxIN).
Pulse width or duty cycle measurement is supported in Gated Timer Mode where the
operation of a timer is controlled by the ‘gate’ level on its external input pin TxIN.
In Incremental Interface Mode, the GPT1 timers can be directly connected to the
incremental position sensor signals A and B via the respective inputs TxIN and TxEUD.
Direction and count signals are internally derived from these two input signals, so, the
contents of timer Tx corresponds to the sensor position. The third position sensor signal
TOP0 can be connected to an interrupt input.
The count direction (up/down) for each timer is programmable by software or may
additionally be altered dynamically by an external signal (TxEUD) to facilitate tasks such
as position tracking.
The core timer T3 has an output toggle latch (T3OTL) which changes its state on each
timer overflow/underflow. The state of this latch may be used internally to concatenate
the core timer with the respective auxiliary timers resulting in 32/33-bit timers/counters
for measuring long time periods with high resolution.
Various reload or capture functions can be selected to reload timers or capture a timer’s
contents triggered by an external signal or a selectable transition of toggle latch T3OTL.
The maximum resolution of the timers in module GPT1 is 8 CPU clock cycles (= 16 TCL).
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Capture/Compare (CAPCOM) Units
The CAPCOM units are typically used to handle high speed I/O tasks such as pulse and
waveform generation, pulse width modulation (PWM), Digital to Analog (D/A)
conversion, software timing, or time recording relative to external events.
A number of dedicated timers with reload registers provide independent time bases for
the capture/compare channels. The input clock for the timers is programmable to several
prescaled values of the internal CPU clock, or may be derived from an overflow/
underflow of timer T3 in module GPT1 (for CAPCOM2 timers). This provides a wide
range of variation for the timer period and resolution and allows precise adjustments to
the application specific requirements. In addition, external inputs for the CAPCOM units
allow event scheduling for the capture/compare registers relative to external events.
The CAPCOM2 unit supports generation and control of timing sequences on up to
16 channels (12 I/O pins) with a maximum resolution of 8 CPU clock cycles. The
capture/compare register array contains 16 dual purpose capture/compare registers,
each of which may be individually allocated to either CAPCOM2 timer T7 or T8, and
programmed for capture or compare function. Twelve registers have port pins
associated with them: they serve as input pins for triggering the capture function, or as
output pins to indicate the occurrence of a compare event.
When a capture/compare register has been selected for capture mode, the current
contents of the allocated timer will be latched (captured) into the capture/compare
register in response to an external event at the port pin which is associated with this
register. In addition, a specific interrupt request for this capture/compare register is
generated. Either a positive, a negative, or both a positive and a negative external signal
transition at the pin can be selected as the triggering event. The contents of all registers
which have been selected for one of the five compare modes are continuously compared
with the contents of the allocated timers. When a match occurs between the timer value
and the value in a capture/compare register, specific actions will be taken based on the
selected compare mode.
The CAPCOM6 unit provides three capture/compare channels and one additional
compare channel. The three capture/compare channels can control two output lines
each, which can be programmed to generate non-overlapping pulse patterns. The
additional compare channel may either generate a separate output signal or modulate
the output signals of the three other channels. The active level for each output can be
selected individually.
Versatile multichannel PWM signals can be generated: controlled either internally via a
timer or externally, for example via hall sensors. The trap function allows the outputs to
be driven to a defined level in response to an external signal.
Note: Multichannel PWM modes are only available in devices with a full-function
CAPCOM6, not in the reduced CAPCOM6.
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Watchdog Timer
The Watchdog Timer is one of the fail-safe mechanisms implemented in the C164CM to
prevent the controller from malfunctioning for longer periods of time.
The Watchdog Timer is always enabled after a reset of the chip, and can be disabled
only for the time interval before the EINIT (end of initialization) instruction has been
executed. Thus, the chip’s start-up procedure is always monitored. The software must
be designed to service the Watchdog Timer before it overflows. If the software fails to do
so, due to either hardware or software related failures, the Watchdog Timer overflows
and generates an internal hardware reset and pulls the RSTOUT pin low to allow
external hardware components to reset.
The Watchdog Timer is a 16-bit timer, clocked with the CPU clock divided by 2, 4, 128,
or 256. The high byte of the Watchdog Timer register can be set to a prespecified reload
value (stored in WDTREL) to allow further variation of the monitored time interval. Each
time it is serviced by the application software, the high byte of the Watchdog Timer is
reloaded. Thus, time intervals between 21 µs and 671 ms can be monitored
(@ 25 MHz). The default Watchdog Timer interval after reset is 5.2 ms (@ 25 MHz).
2.5
Power Management Features
The basic power reduction modes (Idle and Power Down) are enhanced by additional
power management features (see below). These features can be combined to reduce
the controller’s power consumption to correspond to the application’s possible minimum.
• Flexible clock generation
• Flexible peripheral management (peripherals can be dis/enabled separately or in
groups)
• Periodic wakeup from Idle mode via RTC timer
The listed features provide effective means to realize standby conditions for the system
with an optimum balance between power reduction (standby time) and peripheral
operation (system functionality).
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Flexible Clock Generation
The flexible clock generation system combines a variety of improved mechanisms (partly
user controllable) to provide the C164CM modules with clock signals. This is especially
important in power sensitive modes such as standby operation.
The power optimized oscillator generally reduces the amount of power which is
consumed in order to generate the clock signal within the C164CM.
The clock system efficiently controls the amount of power which is consumed in order
to distribute the clock signal within the C164CM.
Slowdown operation is achieved by dividing the oscillator clock by a programmable
factor (1 … 32) resulting in a low frequency device operation which significantly reduces
the overall power consumption.
Flexible Peripheral Management
Flexible peripheral management provides a mechanism to enable and disable each
peripheral module separately. In each situation (such as several system operating
modes, standby, etc.) only those peripherals may be kept running which are required for
the specified functionality. All others may be switched off. It also allows the operation
control of entire groups of peripherals including the power required for generating and
distributing their clock input signal. Other peripherals may remain active: for example, in
order to maintain communication channels. The registers of separately disabled
peripherals (not within a disabled group) can still be accessed.
Periodic Wakeup from Idle or Sleep Mode
Periodic wakeup from Idle mode or from Sleep mode combines the drastically reduced
power consumption in Idle/Sleep mode (in conjunction with the additional power
management features) with a high level of system availability. External signals and
events can be scanned (at a lower rate) by periodically activating the CPU and selected
peripherals which then return to powersave mode after a short time. This greatly reduces
the system’s average power consumption. Idle/Sleep mode can also be terminated by
external interrupt signals.
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2.6
Protected Bits
The C164CM provides a special mechanism to protect bits which can be modified by the
on-chip hardware from being changed unintentionally by software accesses to related
bits (see also Chapter 4).
The following bits are protected:
Table 2-1
C164CM Protected Bits
Register
Bit Name
Notes
T2IC, T3IC, T4IC
T2IR, T3IR, T4IR
GPT1 timer interrupt request flags
T3CON
T3OTL
GPT1 timer output toggle latches
T7IC, T8IC
T7IR, T8IR
CAPCOM2 timer interrupt request flags
S0TIC, S0TBIC
S0TIR, S0TBIR
ASC0 transmit (buffer) interrupt request
flags
S0RIC, S0EIC
S0RIR, S0EIR
ASC0 receive/error interrupt request flags
S0CON
S0REN
ASC0 receiver enable flag
SSCTIC, SSCRIC
SSCTIR, SSCRIR
SSC transmit/receive interrupt request flags
SSCEIC
SSCEIR
SSC error interrupt request flag
SSCCON
SSCBSY
SSC busy flag
SSCCON
SSCBE, SSCPE
SSC error flags
SSCCON
SSCRE, SSCTE
SSC error flags
ADCIC, ADEIC
ADCIR, ADEIR
ADC end-of-conv./overrun intr. request flag
ADCON
ADST, ADCRQ
ADC start flag/injection request flag
CC31IC … CC16IC CC31IR … CC16IR Fast external interrupt request flags
TFR
TFR.15, 14, 13
Class A trap flags
TFR
TFR.7, 3, 2, 1, 0
Class B trap flags
P1H
P1H.7 … P1H.0
Those bits of PORT1 used for CAPCOM2
P8
P8.3 … P8.0
All bits of Port 8 used for CAPCOM2
ISNC
RTCIR
Interrupt node sharing request flag
XP0IC, XP3IC
XP0IR, XP3IR
CAN and PLL/RTC interrupt request flags
Σ = 62 protected bits.
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Derivatives
Memory Organization
3
Memory Organization
The memory space of the C164CM is configured in a “Von Neumann” architecture. This
means that code and data are accessed within the same linear address space. All of the
physically separated memory areas, including internal ROM/Flash/OTP (where
integrated), internal RAM, the internal Special Function Register Areas (SFRs and
ESFRs), the address areas for integrated XBUS peripherals and external memory are
mapped into one common address space.
The C164CM provides a total addressable memory space of 16 MBytes. This address
space is arranged as 256 segments of 64 KBytes each, and each segment is again
subdivided into four data pages of 16 KBytes each (see Figure 3-1).
FF’FFFF
255
H
255...2
254...129
128
01’FFFF
80’0000
127
H
H
Data Page 7
64
40’0000
63
62...12
H
0A’FFFF
11
Segment 1
126...65
H
Data Page 6
01’8000
H
Alternate
ROM
Area
10
9
01’0000
8
7
08’0000
H
Data Page 3
H
Figure 3-1
User’s Manual
Segment 0
64 KByte
External Addressing Capability
6
5
4
3
2
02’FFFF
01’FFFF
1
0
00’0000
H
H
Data Page 2
Internal
ROM
Area
00’0000
H
Total Address Space
16 MByte, Segments 255...0
Segments 1 and 0
64 + 64 KByte
H
MCA05131
Address Space Overview
3-1
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C164CM/C164SM
Derivatives
Memory Organization
Most internal memory areas are mapped into segment 0, the system segment. The
upper 4 KBytes of segment 0 (00’F000H … 00’FFFFH) hold the Internal RAM and
Special Function Register Areas (SFR and ESFR). The lower 32 KBytes of segment 0
(00’0000H … 00’7FFFH) may be occupied by a portion of the on-chip ROM/Flash/OTP
memory and is called the Internal ROM area. This ROM area can be remapped to
segment 1 (01’0000H … 01’7FFFH), to enable external memory access in the lower half
of segment 0, or the internal ROM may be disabled completely.
Code and data may be stored in any part of the internal memory areas, except for the
SFR blocks, which may be used for control/data, but not for instructions.
Note: Accesses to the internal ROM area on ROMless devices will produce
unpredictable results.
Bytes are stored at even or odd byte addresses. Words are stored in ascending memory
locations with the low byte at an even byte address followed by the high byte at the next
odd byte address. Double words (code only) are stored in ascending memory locations
as two subsequent words. Single bits are always stored in the specified bit position at a
word address. Bit position 0 is the least significant bit of the byte at an even byte address,
and bit position 15 is the most significant bit of the byte at the next odd byte address. Bit
addressing is supported for a portion of the Special Function Registers, a portion of the
internal RAM, and for the General Purpose Registers.
xxxx6 H
15
14
Bits
8
xxxx5 H
7
6
Bits
0
xxxx4 H
Byte
xxxx3 H
Byte
xxxx2 H
Word (High Byte)
xxxx1 H
Word (Low Byte)
xxxx0 H
xxxxF H
MCD01996
Figure 3-2
Storage of Words, Bytes, and Bits in a Byte Organized Memory
Note: Byte units forming a single word or a double word must always be stored within
the same physical (internal, external, ROM, RAM) and organizational (page,
segment) memory area.
User’s Manual
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Derivatives
Memory Organization
3.1
Internal ROM Area
The C164CM may reserve an address area of variable size (depending on the version)
for on-chip mask-programmable ROM/Flash/OTP memory (organized as X × 32). The
lower 32 KBytes of this on-chip memory block are referred to as “Internal ROM Area”.
Internal ROM accesses are globally enabled or disabled via bit ROMEN in register
SYSCON. This bit is set during reset according to the level on pin EA, or may be altered
via software. If enabled, the internal ROM area occupies the lower 32 KBytes of either
segment 0 or segment 1 (alternate ROM area). This mapping is controlled by bit ROMS1
in register SYSCON.
Note: The size of the internal ROM area is independent of the actual size of the
implemented Program Memory. Also devices with less than 32 KBytes of Program
Memory or without any Program Memory will have this 32-KByte area occupied if
the Program Memory is enabled. Devices with a larger Program Memory provide
the mapping option only for the internal ROM area.
Devices with a Program Memory size above 32 KBytes expand the ROM area from the
middle of segment 1, starting at address 01’8000H.
The internal Program Memory can be used for both code (instructions) and data
(constants, tables, etc.) storage.
Code fetches are always made on even byte addresses. The highest possible code
storage location in the internal Program Memory is either xx’xxFEH for single word
instructions, or xx’xxFCH for double word instructions. The respective location must
contain a branch instruction (unconditional), because sequential boundary crossing from
internal Program Memory to external memory is not supported and causes erroneous
results.
Any word and byte data read accesses may use the indirect or long 16-bit addressing
modes. There is no short addressing mode for internal ROM operands. Any word data
access is made to an even byte address. The highest possible word data storage
location in the internal Program Memory is xx’xxFEH. For PEC data transfers the internal
Program Memory can be accessed independent of the contents of the DPP registers via
the PEC source and destination pointers.
The internal Program Memory is not provided for single bit storage, and therefore it is not
bit-addressable.
Note: The ‘x’ in the locations above depend on the available Program Memory and on
the mapping.
The internal Program Memory may be enabled, disabled or mapped into segment 0 or
segment 1 under software control. Chapter 22 describes this and indicates precautions
which must be taken to prevent system crashes.
User’s Manual
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Derivatives
Memory Organization
3.2
Internal RAM and SFR Area
The IRAM/SFR area is located within data page 3 and provides access to the Internal
RAM (IRAM, organized as X × 16) and to two 512-Byte blocks of Special Function
Registers (SFRs).
The C164CM provides 2 KBytes of IRAM.
00’FFFF
00’FFFF
H
H
SFR Area
IRAM/SFR
00’F000
H
Data Page 3
X-Peripherals
00’E000
IRAM
H
00’F600
Reserved
H
Reserved
00’F200
H
ESFR Area
Data Page 2
00’C000
H
CAN1
00’F000
H
00’EF00
H
Ext. Memory
Reserved
00’8000
00’E000
H
H
Note: New XBUS peripherals will be preferably placed into the reserved areas,
which now access external memory (bus cycles executed).
MCA05132
Figure 3-3
User’s Manual
System Memory Map
3-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
Memory Organization
Note: The upper 256 Bytes of the SFR area, the ESFR area, and the Internal RAM are
bit-addressable (see shaded blocks in Figure 3-3).
Code accesses are always made on even byte addresses. The highest possible code
storage location in the Internal RAM is either 00’FDFEH for single word instructions or
00’FDFCH for double word instructions. The respective location must contain a branch
instruction (unconditional), because sequential boundary crossing from Internal RAM to
the SFR area is not supported and causes erroneous results.
Any word and byte data in the Internal RAM can be accessed via indirect or long 16-bit
addressing modes, if the selected DPP register points to data page 3. Any word data
access is made on an even byte address. The highest possible word data storage
location in the internal RAM is 00’FDFEH. For PEC data transfers, the internal RAM can
be accessed independent of the contents of the DPP registers via the PEC source and
destination pointers.
The upper 256 Bytes of the Internal RAM (00’FD00H through 00’FDFFH) and the GPRs
of the current bank are provided for single bit storage, and thus they are bit-addressable.
System Stack
The system stack may be defined within the Internal RAM. The size of the system stack
is controlled by bitfield STKSZ in register SYSCON (see Table 3-1).
Table 3-1
System Stack Size Encoding
<STKSZ>
Stack Size (words) Internal RAM Addresses (words)
0 0 0B
256
00’FBFEH … 00’FA00H (Default after Reset)
0 0 1B
128
00’FBFEH … 00’FB00H
0 1 0B
64
00’FBFEH … 00’FB80H
0 1 1B
32
00’FBFEH … 00’FBC0H
1 0 0B
512
00’FBFEH … 00’F800H
1 0 1B
–
Reserved. Do not use this combination.
1 1 0B
–
Reserved. Do not use this combination.
1 1 1B
1024
00’FDFEH … 00’F600H (Note: No circular stack)
For all system stack operations the on-chip RAM is accessed via the Stack Pointer (SP)
register. The stack grows downward from higher towards lower RAM address locations.
Only word accesses are supported to the system stack. A stack overflow (STKOV)
register and a stack underflow (STKUN) register are provided to control the lower and
upper limits of the selected stack area. These two stack boundary registers can be used
both for protection against data destruction and for implementation of a circular stack
with hardware-supported system stack flushing and filling (except for option ‘111’). The
technique for implementing the circular stack is described in Chapter 22.
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Derivatives
Memory Organization
General Purpose Registers
The General Purpose Registers (GPRs) use a block of 16 consecutive words within the
Internal RAM. The Context Pointer (CP) register determines the base address of the
currently active register bank. This register bank may consist of up to 16 Word-GPRs
(R0, R1, … R15) and/or of up to 16 Byte-GPRs (RL0, RH0, … RL7, RH7). The sixteen
Byte-GPRs are mapped onto the first eight Word-GPRs (see Table 3-2).
In contrast to the system stack, a register bank grows from lower towards higher address
locations and occupies a maximum space of 32 Bytes. The GPRs are accessed via short
2-, 4-, or 8-bit addressing modes using the Context Pointer (CP) register as base
address (independent of the current DPP register contents). Additionally, each bit in the
currently active register bank can be accessed individually.
Table 3-2
Mapping of General Purpose Registers to RAM Addresses
Internal RAM Address
Byte Registers
Word Register
<CP> + 1EH
–
R15
<CP> + 1CH
–
R14
<CP> + 1AH
–
R13
<CP> + 18H
–
R12
<CP> + 16H
–
R11
<CP> + 14H
–
R10
<CP> + 12H
–
R9
<CP> + 10H
–
R8
<CP> + 0EH
RH7
RL7
R7
<CP> + 0CH
RH6
RL6
R6
<CP> + 0AH
RH5
RL5
R5
<CP> + 08H
RH4
RL4
R4
<CP> + 06H
RH3
RL3
R3
<CP> + 04H
RH2
RL2
R2
<CP> + 02H
RH1
RL1
R1
<CP> + 00H
RH0
RL0
R0
The C164CM supports fast register bank (context) switching. Multiple register banks can
physically exist within the Internal RAM at the same time. Only the register bank selected
by the Context Pointer register (CP) is active at a given time, however. Selecting a new
active register bank is done simply by updating the CP register. A particular Switch
Context (SCXT) instruction performs register bank switching and automatically saves
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Derivatives
Memory Organization
the previous context. The number of implemented register banks (arbitrary sizes) is
limited only by the size of the available internal RAM.
Details on using, switching, and overlapping register banks are described in Chapter 22.
PEC Source and Destination Pointers
The 16 word locations in the Internal RAM from 00’FCE0H to 00’FCFEH (just below the
bit-addressable section) are provided as source and destination address pointers for
data transfers on the eight PEC channels. Each channel uses a pair of pointers stored
in two subsequent word locations with the source pointer (SRCPx) on the lower and the
destination pointer (DSTPx) on the higher word address (x = 7 … 0).
00 FD00 H
00 FCFE H
DSTP7
00 FCFE H
00 FCFC H
SRCP7
00 FCE0 H
00 FCDE H
PEC
Source
and
Destination
Pointers
Internal
RAM
00 FCE2 H
DSTP0
00 F600 H
00 FCE0 H
SRCP0
00 F5FE H
MCD03903
Figure 3-4
Location of the PEC Pointers
Whenever a PEC data transfer is performed, the pair of source and destination pointers
(selected by the specified PEC channel number) is accessed independently of the
current DPP register contents. The locations referred to by these pointers are accessed
independently of the current DPP register contents as well. If a PEC channel is not used,
the corresponding pointer locations are available and can be used for word or byte data
storage.
For more details on the use of the source and destination pointers for PEC data transfers
see Chapter 5.
User’s Manual
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Derivatives
Memory Organization
Special Function Registers
The functions of the CPU, the bus interface, the IO ports, and the on-chip peripherals of
the C164CM are controlled via a number of Special Function Registers (SFRs). These
SFRs are arranged within two areas of 512 Bytes each. The first register block, the SFR
area, is located in the 512 Bytes above the Internal RAM (00’FFFFH … 00’FE00H). The
second register block, the Extended SFR (ESFR) area, is located in the 512 Bytes below
the Internal RAM (00’F1FFH … 00’F000H).
Special Function Registers can be addressed via indirect and long 16-bit addressing
modes. Using an 8-bit offset together with an implicit base address allows word SFRs
and their respective low bytes to be addressed. However, this does not work for the
respective high bytes!
Note: Writing to any byte of an SFR causes the non-addressed complementary byte to
be cleared!
The upper half of each register block is bit-addressable, so the respective control/status
bits can be modified directly or checked using bit addressing.
When accessing registers in the ESFR area using 8-bit addresses or direct bit
addressing, an Extend Register (EXTR) instruction is required beforehand to switch the
short addressing mechanism from the standard SFR area to the Extended SFR area.
This is not required for 16-bit and indirect addresses. The GPRs R15 … R0 are
duplicated, i.e. they are accessible within both register blocks via short 2-, 4- or 8-bit
addresses without switching.
ESFR_SWITCH_EXAMPLE:
EXTR
#4
MOV
ODP8, #data16
BFLDL DP8, #mask, #data8
BSET
DP1H.7
MOV
T8REL, R1
;---MOV
;Switch to ESFR area for next 4 instr.
;ODP2 uses 8-bit reg addressing
;Bit addressing for bit fields
;Bit addressing for single bits
;T8REL uses 16-bit mem address,
;R1 is duplicated into the ESFR space
;(EXTR is not required for this access)
;----------------- ;The scope of the EXTR #4 instruction …
;… ends here!
T8REL, R1
;T8REL uses 16-bit mem address,
;R1 is accessed via the SFR space
In order to minimize the use of the EXTR instructions the ESFR area primarily holds
registers which are mainly required for initialization and mode selection. Registers which
need to be accessed frequently are allocated to the standard SFR area wherever
possible.
Note: The tools are equipped to monitor accesses to the ESFR area and will
automatically insert EXTR instructions, or issue a warning in case of missing or
excessive EXTR instructions.
User’s Manual
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Derivatives
Memory Organization
3.3
External Memory Space
The C164CM is capable of using an address space of up to 16 MBytes. Only parts of this
address space are occupied by internal memory areas. All addresses which are not used
for on-chip memory (ROM/Flash/OTP or RAM) or for registers may reference external
memory locations. This external memory is accessed via the C164CM’s external bus
interface.
The C164CM supports four different bus types:
•
•
•
•
Multiplexed 16-bit Bus
Multiplexed 8-bit Bus
Demultiplexed 16-bit Bus
Demultiplexed 8-bit Bus
with address and data on PORT0 (Default after Reset)
with address and data on PORT0/P0L
with address on PORT1 and data on PORT0
with address on PORT1 and data on P0L
Due to the low pin-count of the C164CM the external memory which can be directly
addressed via the address bus is quite limited. However, the majority of applications is
expected to work with on-chip memories and use the bus interface mainly for accessing
small external memories or for controlling external peripherals.
Two memory sizes are supported:
• 8-bit Multiplexed Bus: 2 KBytes
• Any other bus mode: 64 KBytes
with A10 … A0 on PORT01)
with A15 … A0 on PORT0 or PORT1
Memory model and bus mode are selected during reset by pin EA and PORT0 pins. For
further details about the external bus configuration and control please refer to Chapter 9.
External word and byte data can only be accessed via indirect or long 16-bit addressing
modes using one of the four DPP registers. There is no short addressing mode for
external operands. Any word data access is made to an even byte address.
For PEC data transfers the external memory in segment 0 can be accessed
independently of the contents of the DPP registers via the PEC source and destination
pointers.
The external memory is not provided for single bit storage and therefore it is not
bitaddressable.
1)
This bus mode offers lowest performance but allows concurrent operation of external bus interface and
standard serial interfaces.
User’s Manual
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Derivatives
Memory Organization
3.4
Crossing Memory Boundaries
The address space of the C164CM is implicitly divided into equally sized blocks of
different granularity and into logical memory areas. Crossing the boundaries between
these blocks (code or data) or areas requires special attention to ensure that the
controller executes the desired operations.
Memory Areas are partitions of the address space assigned to different kinds of
memory (if provided at all). These memory areas are the Internal RAM/SFR area, the
internal ROM/Flash/OTP (if available), the on-chip X-Peripherals (if integrated), and the
external memory.
Accessing subsequent data locations which belong to different memory areas is no
problem. However, when executing code, the different memory areas must be switched
explicitly via branch instructions. Sequential boundary crossing is not supported and
leads to erroneous results.
Note: Changing from the external memory area to the internal RAM/SFR area takes
place within segment 0.
Segments are contiguous blocks of 64 KBytes each. They are referenced via the Code
Segment Pointer CSP for code fetches and via an explicit segment number for data
accesses overriding the standard DPP scheme.
During code fetching, segments are not changed automatically, but rather must be
switched explicitly. The instructions JMPS, CALLS and RETS will do this.
In larger sequential programs, make sure that the highest used code location of a
segment contains an unconditional branch instruction to the respective following
segment to prevent the prefetcher from trying to leave the current segment.
Data Pages are contiguous blocks of 16 KBytes each. They are referenced via the data
page pointers DPP3 … DPP0 and via an explicit data page number for data accesses
overriding the standard DPP scheme. Each DPP register can select one of the possible
1024 data pages. The DPP register which is used for the current access is selected via
the two upper bits of the 16-bit data address. Therefore, subsequent 16-bit data
addresses which cross the 16-KByte data page boundaries will use different data page
pointers, while the physical locations need not be subsequent within memory.
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Derivatives
Memory Organization
3.5
Protection of the On-Chip Mask ROM
The on-chip mask ROM of the C164CM can be protected against read accesses of both
code and data. ROM protection is established during the production process of the
device (a ROM mask can be ordered with a ROM protection or without it). No software
control is possible, i.e. the ROM protection cannot be disabled or enabled by software.
When a device has been produced with ROM protection active, the ROM contents are
protected against unauthorized access by the following measures:
• No data read accesses to the internal ROM are permitted by any instruction which is
executed from any location outside the on-chip mask ROM (including IRAM, XRAM,
and external memory).
A program cannot read any data out of the protected ROM from outside.
The read data will be replaced by the default value 009BH for any read access to any
location.
• No codes fetches from the internal ROM can be made by any instruction which is
executed from any location outside the on-chip mask ROM (including IRAM, XRAM,
and external memory).
A program cannot branch to a location within the protected ROM from outside. This
applies to JUMPs as well as to RETurns. A called routine within RAM or external
memory can never return to the protected ROM.
The fetched code will be replaced by the default value 009BH for any access to any
location. This default value will be decoded as the instruction “TRAP #00” which will
restart program execution at location 00’0000H.
Note: ROM protection may be used for applications where the complete software fits into
the on-chip ROM, or where the on-chip ROM holds initialization software which is
then replaced by external application software (for example). In the latter case no
data (constants, tables, etc.) can be stored within the ROM. The ROM itself should
be mapped to segment 1 before branching outside, so an interrupt vector table
can be established in external memory.
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Derivatives
Memory Organization
3.6
OTP Memory Programming
During normal operation the One-Time-Programmable (OTP) memory appears like a
standard ROM. In the special OTP programming modes, however, the OTP memory can
be programmed by writing to its special programming interface. Programming is
executed in units of 16-bit words and each programming cycle takes about 100 µs. OTP
programming requires an external programming voltage of VPP = 11.5 V ± 5% which is
applied to pin EA/VPP.
The OTP memory can be programmed in CPU Host Mode (CHM) via software or in
External Host Mode (EHM) via external hardware.
10 ns
100 ns
ADDR
OTP Word Address
DATA
Programming Data
120 ns
100 µs
1)
WR
Vpp
10 µs
100 ns
2)
EA/Vpp
< VDD
50 ns
50 ns
CE
MCT05093
1)
2)
Earliest possible begin of next programming cycle.
VPP must be switched off for verify accesses, it may remain on for subsequent programming cycles.
The special signal RSEL must fulfill the same timing requirements as the address lines.
Note: All timings represent minimum values.
Figure 3-5
User’s Manual
OTP Programming Cycle
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Derivatives
Memory Organization
Verify cycles may be executed to ensure correct programming. Programming cycles and
verify cycles may alternate in order to check each word immediately. However, the total
programming time can be reduced by programming blocks of data continuously and then
verifying the blocks (this saves the VPP settling time).
Note: The programming voltage VPP must be applied for all programming cycles and
must be removed for all other accesses, i.e. verify cycles and standard read
cycles. The setting time is 10 µs in each case.
In EHM this must be controlled by the external host, in CHM the CPU may control
VPP via an output port line.
50 ns
ADDR
OTP Word Address
15 ns
DATA
50 ns
RD
10 µs
Vpp
EA/Vpp
< VDD
MCT05094
The special signals CE and RSEL must fulfill the same timing requirements as the address lines.
Note: All timings represent minimum values.
Figure 3-6
OTP Verify/Read Cycle
The programming cycles can be controlled in two different ways:
In CPU Host Mode (CHM) the CPU of the C164CM itself controls the programming
cycles via the OTP programming interface. The programming routine must be fetched
from outside the OTP memory (on-chip RAM or external memory).
In External Host Mode (EHM) the C164CM is put into emulation mode where the CPU
and the generic peripherals are disabled. The on-chip OTP memory can be accessed by
an external master via the C164CM’s bus interface. The bus interface signals change
their direction in this mode.
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Memory Organization
3.6.1
Selecting an OTP Programming Mode
Both programming modes can only be enabled via reset configuration.
CPU Host Mode (CHM) is enabled after an external reset by pulling low pin P0L.2 in
either standard startup mode or in bootstrap loader mode. Pins P0L.5 … 0 here
represent 11’1011B (standard) or 10’1011B (BSL). After a single-chip mode reset CHM
is automatically enabled without additional control.
Note: When CHM is enabled in standard startup mode program execution will always
begin out of external memory, disregarding the level on pin EA/VPP.
When CHM is enabled in bootstrap loader mode the programming routine(s) can
be loaded via the serial interface. This allows in-system programming of an empty
OTP module.
External Host Mode (EHM) is enabled by selecting emulation mode (P0L.0 = ‘0’) and
also pulling low pin P0L.5. Pins P0L.5 … 0 represent 01’1110B in this case.
CPU Host Mode Programming
CHM is useful for in-system programming, especially combined with the bootstrap loader
mode. CHM programming cycles are controlled via the C164CM’s programming
interface which replaces the external bus interface signals. Pin EA/VPP accepts the
external programming voltage during programming cycles (see diagram).
The programming interface is realized as an XBUS peripheral and uses the address area
00’EDC0H - 00’EDDFH. The interface is activated only in programming mode and cannot
be accessed in all other cases. The OTP module’s interface signals are not externally
asserted but rather controlled via three registers:
Table 3-3
Register
Name
OTP Programming Interface Registers
Physical Description
Address
Reset
Value
OPCTRL EDC0H
Control register, provides the control signals and the
upper 8 address lines (A23 … A16).
0007H
OPAD
EDC2H
Address register provides the lower 15 address lines
of the physical OTP word address (A15 … A1).
Note: Address line A0 is not evaluated.
0000H
OPDAT
EDC4H
Data register provides the word to be stored or read
from the module.
0000H
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Derivatives
Memory Organization
External Host Mode Programming
In this mode the signals to control a programming cycle are generated by an external
host using the C164CM’s bus interface. The external host provides the data to be
programmed. The C164CM itself is switched off and its OTP module can be accessed
like standalone memory.
In External Host Mode the following port pins represent the interface to the C164CM’s
OTP module:
External Host Mode Interface Signals1)
Table 3-4
Signal
Pin
Description
ADDR
P1H.7 - P1L.1
Physical OTP word address (address line A0 is not
evaluated)
DATA
P0H.7 - P0L.0
Word to be programmed or verified
RD
P20.0/RD
Verify cycle control
WR
P20.1/WR
Programming cycle control
CE
P5.6
OTP enable signal
RSEL
P5.7
Control signal RSEL used for protection lock control,
must be ‘0’ for OTP programming cycles
RSTOUT
RSTOUT
Must be held high (pullup resistor)
VPP
P20.5/EA/VPP
External programming voltage
1)
The specific behavior of the C164CM in emulation mode (prerequisite for EHM) is described in Section 20.4.1.
The access cycles generated by the external host must fulfill the timing requirements
shown in the timing diagrams above.
Note: EHM is a variety of the emulation mode where pin P0.15 (P0L.7) is inverted during
the reset configuration. This influences the selected clock generation mode.
For EHM operation direct drive or prescaler mode must be configured. If the
on-chip oscillator is not supplied with a clock signal the oscillator watchdog must
not be disabled, so the PLL can provide the clock signal instead.
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Memory Organization
3.6.2
OTP Module Addressing
When the OTP module is read in normal mode (via its CPU interface) it appears like a
standard ROM within the internal ROM area and can also be mapped to the respective
lower half of segment 0 or segment 1:
For segment 0 mapping it uses locations 00’0000H to 00’7FFFH,
for segment 1 mapping it uses locations 01’0000H to 01’7FFFH.
In programming mode, however, the OTP module is addressed physically via the
external interface or the OTP programming interface. In this case the OTP module
appears as a contiguous block using the (physical) addresses 00’0000H to 00’7FFFH.
Note: When entering a programming mode (EHM or CHM) the on-chip OTP module is
disabled independent from the selection via pin EA. The programming software (in
CHM) must not enable the OTP module’s CPU interface by setting bit ROMEN in
register SYSCON.
OPCTRL
OTP Control Register
15
14
13
12
XReg (EDC0H)
11
10
9
8
Reset Value: 0007H
7
6
5
4
3
SEGAD
-
-
-
-
RS
rw
-
-
-
-
rw
2
1
0
CEQ WRQ RDQ
rw
rw
rw
Bit
Function
RDQ
Read Signal (active low)
0:
OTP module selected for a verify read access
1:
Read access is completed
WRQ
Write Signal (active low)
0:
OTP module selected for a write access (programming)
1:
Write access is completed
CEQ
OTP Module Enable Signal (active low)
0:
OTP module is selected
1:
OTP module is deselected, no access
RS
Register Select Signal (RSEL)
0:
Access the OTP memory module
1:
Access the control section (read protection control)
SEGAD
Physical Segment Address
Provides the upper (physical) address lines (A23 … A16) to the OTP
memory module (SEGAD must be 00H for the C164CM)
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Derivatives
Memory Organization
An OTP programming/verify cycle is executed by a sequence of accesses to the
programming interface which emulate the externally controlled cycles (see example
below).
OTP Programming Example
The on-chip OTP memory is programmed in CHM executing the following procedure:
Note: The example below assumes segment 0 (RH3 = 00H).
MOV
MOV
R1, #OTP_START
R2, #DATA_BLOCK
;R1 = OTP pointer
;R2 = Source data pointer
MOV
MOV
BSET
CALL
R3, #0003H
DPP3:OPCTRL, R3
VPP_ENABLE
MICROSEC_010
;03H: enable module, cmd. idle
;Initially enable the OTP module
;External progr. voltage ON
;Let VPP settle for 10 µs
PROG_OTP_WORD:
MOV
DPP3:OPAD, R1
MOV
R0, [R2+]
MOV
DPP3:OPDAT, R0
MOV
R3, #0001H
MOV
DPP3:OPCTRL, R3
CALL
MICROSEC_100
MOV
R3, #0003H
MOV
DPP3:OPCTRL, R3
ALT_VERIFY:
BCLR
VPP_ENABLE
CALL
MICROSEC_010
MOV
R3, #0002H
MOV
DPP3:OPCTRL, R3
MOV
R3, #0003H
MOV
DPP3:OPCTRL, R3
CMP
R0, DPP3:OPDAT
JMP
cc_NE, PROG_FAILED
BSET
VPP_ENABLE
CALL
MICROSEC_010
User’s Manual
;Select current address
;Move source data word …
;… to data register
;01H: enable module, WR active
;Select OTP module for write access
;Keep the write signal low for 100 µs
;03H: enable module, cmd. idle
;Trailing edge of write signal
;This block only for alternating verify
;External progr. voltage Off
;Let VPP settle for 10 µs
;02H: enable module, RD active
;Select OTP module for read access
;03H: enable module, cmd. idle
;Trailing edge of read signal
;Verify data reg. with original data
;External progr. voltage ON
;Let VPP settle for 10 µs
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Derivatives
Memory Organization
PROG_LOOP:
CMPI2 R1, #BLOCK_LIMIT
;Next OTP location
JMP
cc_ULE, PROG_OTP_WORD;Repeat for the whole data block
BCLR
CALL
VPP_ENABLE
MICROSEC_010
;External progr. voltage Off
;Let VPP settle for 10 µs
;Block verification could be …
;… executed here
MOV
MOV
R3, #0007H
DPP3:OPCTRL, R3
User’s Manual
;OTP module deselected
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Derivatives
Memory Organization
3.6.3
Read Protection Control
The on-chip OTP memory can be protected against unauthorized accesses (read or
execute).
When the read protection is active …
• no programming cycles can be executed (neither in EHM nor in CHM)
• no verify cycles can be executed
• OTP locations can only be read by instructions fetched from the OTP itself
The OTP read protection is activated by a specific programming cycle which has the
register select signal (RSEL) active (contrary to normal programming cycles). This
special cycle must write the value 0000H to register address 000EH. A verify cycle can
be executed directly after activating the read protection, i.e. without leaving programming
mode. The active read protection is indicated with data bit D0 = ‘0’.
Note: OTP read protection is irreversible. When the OTP read protection was activated
once it remains active for each and every subsequent access. Also subsequent
programming cycles are no more possible.
OTP Read Protection Example
The OTP read protection is activated in CHM executing the following procedure:
Note: The example below assumes segment 0 (RH0 = 00H).
MOV
MOV
BSET
CALL
MOV
MOV
MOV
MOV
MOV
MOV
CALL
MOV
MOV
BCLR
CALL
R0, #0003H
DPP3:OPCTRL, R0
VPP_ENABLE
MICROSEC_010
R0, #000EH
DPP3:OPAD, R0
R0, #0000H
DPP3:OPDAT, R0
R0, #0009H
DPP3:OPCTRL, R0
MICROSEC_100
R0, #000BH
DPP3:OPCTRL, R0
VPP_ENABLE
MICROSEC_010
;Enable module, cmd. idle
;Initially enable the OTP module
;External progr. voltage ON
;Let VPP settle for 10 µs
;Move special register address …
;… to address register
;Move special control word …
;… to data register
;Select special OTP register …
;… for write access
;Keep the write signal low for 100 µs
;Trailing edge of write signal
;External progr. voltage Off
;Let VPP settle for 10 µs
;Read protection verify could be …
;… executed here
MOV
MOV
R0, #0007H
DPP3:OPCTRL, R0
User’s Manual
;OTP module deselected
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Derivatives
Central Processing Unit (CPU)
4
Central Processing Unit (CPU)
Basic tasks of the Central Processing Unit (CPU) are to fetch and decode instructions,
to supply operands for the Arithmetic and Logic unit (ALU), to perform operations on
these operands in the ALU, and to store the previously calculated results. As the CPU is
the main engine of the C164CM microcontroller, it is also affected by certain actions of
the peripheral subsystem.
Because a four stage pipeline is implemented in the C164CM, up to four instructions can
be processed in parallel. Most instructions of the C164CM are executed in one machine
cycle (2 CPU clock periods) due to this parallelism.
This chapter describes how the pipeline works for sequential and branch instructions in
general, and the hardware provisions which have been made to speed up execution of
jump instructions in particular. General instruction timing is described including standard
and exceptional timing.
While internal memory accesses are normally performed by the CPU itself, external
peripheral or memory accesses are performed by a particular on-chip External Bus
Controller (EBC) which is invoked automatically by the CPU whenever a code or data
address refers to the external address space.
Figure 4-1
User’s Manual
CPU Block Diagram
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Derivatives
Central Processing Unit (CPU)
Whenever possible, the CPU continues operating while an external memory access is in
progress. If external data are required but are not yet available, or if a new external
memory access is requested by the CPU before a previous access has been completed,
the CPU will be held by the EBC until the request can be satisfied. The EBC is described
in a separate chapter.
The on-chip peripheral units of the C164CM work nearly independently of the CPU with
a separate clock generator. Data and control information are interchanged between the
CPU and these peripherals via Special Function Registers (SFRs).
Whenever peripherals need a non-deterministic CPU action, an on-chip Interrupt
Controller compares all pending peripheral service requests against each other and
prioritizes one of them. If the priority of the current CPU operation is lower than the
priority of the selected peripheral request, an interrupt will occur.
There are two basic types of interrupt processing:
• Standard interrupt processing forces the CPU to save the current program status
and return address on the stack before branching to the interrupt vector jump table.
• PEC interrupt processing steals only one machine cycle from the current CPU
activity to perform a single data transfer via the on-chip Peripheral Event Controller
(PEC).
System errors detected during program execution (hardware traps) and external
non-maskable interrupts are also processed as standard interrupts with a very high
priority.
In contrast to other on-chip peripherals, there is a closer conjunction between the
watchdog timer and the CPU. If enabled, the watchdog timer expects to be serviced by
the CPU within a programmable period of time, otherwise it will reset the chip. Thus, the
watchdog timer is able to prevent the CPU from going astray when executing erroneous
code. After reset, the watchdog timer starts counting automatically but, it can be disabled
via software, if desired.
In addition to its normal operation state, the CPU has the following particular states:
• Reset state: Any reset (hardware, software, watchdog) forces the CPU into a
predefined active state.
• IDLE state: The clock signal to the CPU itself is switched off, while the clocks for the
on-chip peripherals keep running.
• SLEEP state: All of the on-chip clocks are switched off (RTC clock selectable),
external interrupt inputs are enabled.
• POWER DOWN state: All of the on-chip clocks are switched off (RTC clock
selectable), all inputs are disregarded.
Transition to an active CPU state is forced by an interrupt (if in IDLE or SLEEP mode) or
by a reset (if in POWER DOWN mode).
The IDLE, SLEEP, POWER DOWN, and RESET states can be entered by specific
C164CM system control instructions.
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Derivatives
Central Processing Unit (CPU)
A set of Special Function Registers is dedicated to the functions of the CPU core:
•
•
•
•
•
•
•
•
General System Configuration
CPU Status Indication and Control
Code Access Control
Data Paging Control
GPRs Access Control
System Stack Access Control
Multiply and Divide Support
ALU Constants Support
4.1
: SYSCON (RP0H)
: PSW
: IP, CSP
: DPP0, DPP1, DPP2, DPP3
: CP
: SP, STKUN, STKOV
: MDL, MDH, MDC
: ZEROS, ONES
Instruction Pipelining
The instruction pipeline of the C164CM partitions instruction processing into four stages,
each of which has a specific task:
1st → FETCH: In this stage, the instruction selected by the Instruction Pointer (IP) and
the Code Segment Pointer (CSP) is fetched from either the internal ROM, internal RAM,
or external memory.
2nd → DECODE: In this stage, the instructions are decoded and, if required, the operand
addresses are calculated and the respective operands are fetched. For all instructions
which implicitly access the system stack, the SP register is either decremented or
incremented as specified. For branch instructions, the Instruction Pointer and the Code
Segment Pointer are updated with the desired branch target address (provided that the
branch is taken).
3rd → EXECUTE: In this stage, an operation is performed on the previously fetched
operands in the ALU. Additionally, the condition flags in the PSW register are updated
as specified by the instruction. Also, all explicit writes to the SFR memory space and all
auto-increment or auto-decrement writes to GPRs used as indirect address pointers are
performed during the execute stage of an instruction.
4th → WRITE BACK: In this stage, all external operands and the remaining operands
within the internal RAM space are written back.
A special feature of the C164CM is the use of so-called injected instructions. Injected
instructions are generated internally by the machine to provide the time needed to
process instructions which cannot be processed within one machine cycle. These
instructions are injected automatically into the decode stage of the pipeline and then they
pass through the remaining stages like every standard instruction. Program interrupts
are performed by means of injected instructions, as well. Although these internally
injected instructions will not be noticed in reality, they are introduced here to ease the
explanation of the pipeline in the following sections.
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Derivatives
Central Processing Unit (CPU)
Sequential Instruction Processing
Each single instruction must pass through each of the four pipeline stages regardless of
whether or not all possible stage operations are actually performed. Because passing
through one pipeline stage takes at least one machine cycle, any isolated instruction
takes at least four machine cycles to be completed. Pipelining, however, allows parallel
(simultaneous) processing of up to four instructions. Thus, most of the instructions seem
to be processed in one machine cycle as soon as the pipeline has been filled once after
reset (see Figure 4-2).
Instruction pipelining increases the average instruction throughput considered over a
certain period of time. In the following, any execution time specification for an instruction
always refers to the average execution time due to pipelined parallel instruction
processing.
1 Machine Cycle
I1
FETCH
DECODE
I2
I3
I4
I5
I6
I1
I2
I3
I4
I5
I1
I2
I3
I4
I1
I2
I3
EXECUTE
WRITEBACK
Time
Figure 4-2
MCT04327
Sequential Instruction Pipelining
Standard Branch Instruction Processing
Instruction pipelining helps to speed up sequential program processing. If a branch is
taken, the instruction which has already been fetched is most likely not the instruction
which must be decoded next. Thus, at least one additional machine cycle is normally
required to fetch the branch target instruction. This extra machine cycle is provided by
means of an injected instruction (see Figure 4-3).
1 Machine Cycle
Injection
BRANCH
In+2
ITARGET
ITARGET+1
ITARGET+2
ITARGET+3
DECODE
In
BRANCH
(IINJECT)
ITARGET
ITARGET+1
ITARGET+2
EXECUTE
...
In
BRANCH
(IINJECT)
ITARGET
ITARGET+1
WRITEBACK
...
...
In
BRANCH
(IINJECT)
ITARGET
FETCH
Time
Figure 4-3
User’s Manual
MCT04328
Standard Branch Instruction Pipelining
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Derivatives
Central Processing Unit (CPU)
If a conditional branch is not taken, there is no deviation from the sequential program
flow, and thus no extra time is required. In this case, the instruction after the branch
instruction will enter the decode stage of the pipeline at the beginning of the next
machine cycle after the decoding of the conditional branch instruction.
Cache Jump Instruction Processing
The C164CM incorporates a jump cache to optimize conditional jumps which are
processed repeatedly within a loop. Whenever a jump on cache is taken, the extra time
to fetch the branch target instruction can be saved and thus the corresponding cache
jump instruction in most cases takes only one machine cycle.
This performance is achieved by the following mechanism:
Whenever a cache jump instruction passes through the decode stage of the pipeline for
the first time (provided that the jump condition is met), the jump target instruction is fetched
as usual, causing a time delay of one machine cycle. In contrast to standard branch
instructions, however, the target instruction of a cache jump instruction (JMPA, JMPR,
JB, JBC, JNB, JNBS) is additionally stored in the cache after having been fetched.
After each repeatedly following execution of the same cache jump instruction, the jump
target instruction is not fetched from program memory but, rather, is taken from the
cache and is injected immediately into the decode stage of the pipeline (see Figure 4-4).
A time saving jump on cache is always taken after the second and any further occurrence
of the same cache jump instruction unless an instruction having the fundamental
capability of changing the CSP register contents (JMPS, CALLS, RETS, TRAP, RETI),
or any standard interrupt has been processed during the period of time between two
following occurrences of the same cache jump instruction.
Injection of Cached
Target Instruction
Injection
1 Machine Cycle
In+2
ITARGET
ITARGET+1
In+2
ITARGET+1
ITARGET+2
DECODE
Cache Jmp
(IINJECT)
ITARGET
Cache Jmp
ITARGET
ITARGET+1
EXECUTE
In
Cache Jmp
(IINJECT)
In
Cache Jmp
ITARGET
WRITEBACK
...
In
Cache Jmp
...
In
Cache Jmp
FETCH
1st Loop Iteration
Repeated Loop Iteration
MCT04329
Figure 4-4
User’s Manual
Cache Jump Instruction Pipelining
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Derivatives
Central Processing Unit (CPU)
4.2
Particular Pipeline Effects
Because up to four different instructions are processed simultaneously, additional
hardware has been used in the C164CM to consider all causal dependencies which may
exist on instructions in different pipeline stages. This functionality is provided without a
loss of performance. This extra hardware (for ‘forwarding’ operand read and write
values) resolves most of the possible conflicts (such as multiple usage of buses) in a time
optimized way; thus, in most cases, the pipeline operates without being noticeable to the
user. However, there are some very rare circumstances in which the C164CM as a
pipelined machine requires attention by the programmer. In these cases, the delays
caused by pipeline conflicts can be used for other instructions in order to optimize
performance.
Context Pointer Updating
An instruction which calculates a physical GPR operand address via the Context Pointer
(CP) register is mostly incapable of using a new CP value, which has been updated by
an immediately preceding instruction. Thus, to ensure that the new CP value is used, at
least one instruction must be inserted between a CP-changing instruction and a
subsequent GPR-using instruction, as shown in the following example:
In
In+1
In+2
:SCXT CP,#0FC00h
:…
:MOV R0,#dataX
;select a new context
;must not be an instruction using a GPR
;write to GPR 0 in the new context
Data Page Pointer Updating
An instruction which calculates a physical operand address via a particular Data
Page Pointer (DPPn) register (n = 0 to 3), is mostly incapable of using a new DPPn
register value which has been updated by an immediately preceding instruction. Thus,
to ensure that the new DPPn register value is used, at least one instruction must be
inserted between a DPPn-changing instruction and a subsequent instruction which
implicitly uses DPPn via a long or indirect addressing mode, as shown in the following
example:
In
In+1
In+2
:MOV
:…
:MOV
User’s Manual
DPP0,#4
;select data page 4 via DPP0
;must not be an instruction using DPP0
DPP0:0000H,R1;move contents of R1 to
;location 01’0000H (in data page 4),
;supposed segment is enabled
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Derivatives
Central Processing Unit (CPU)
Explicit Stack Pointer Updating
None of the RET, RETI, RETS, RETP or POP instructions is capable of correctly using
a new SP register value which has been updated by an immediately preceding
instruction. Thus, in order to use the new SP register value without erroneously
performed stack accesses, at least one instruction must be inserted between an
explicitly SP-writing and any subsequent use of the just mentioned implicitly SP-using
instructions, as shown in the following example:
In
In+1
:MOV
:…
SP,#0FA40H
In+2
:POP
R0
;select a
;must not
;operands
;pop word
;into R0
new top of stack
be an instruction popping
from the system stack
value from new top of stack
Note: Conflicts with instructions writing to the stack (PUSH, CALL, SCXT) are solved
internally by the CPU logic.
Controlling Interrupts
Software modifications (implicit or explicit) of the PSW are made in the execute phase of
the respective instructions. To maintain fast interrupt responses, however, the current
interrupt prioritization round does not consider these changes; that means that an
interrupt request may be acknowledged after the instruction which disables interrupts via
IEN or ILVL or after the following instructions. Time critical instruction sequences
therefore should not begin directly after the instruction disabling interrupts, as shown in
the following examples:
INTERRUPTS_OFF:
BCLR
IEN
<Instr non-crit>
<Instr 1st-crit>
. . .
<Instr last-crit>
INTERRUPTS_ON:
BSET
IEN
CRITICAL_SEQUENCE:
ATOMIC #3
BCLR
IEN
. . .
BSET
IEN
;globally disable interrupts
;non-critical instruction
;begin of
;uninterruptable critical sequence
;end of critical sequence
;globally re-enable interrupts
;immediately block interrupts
;globally disable interrupts
;here is the uninterruptable sequence
;globally re-enable interrupts
Note: The described delay of one instruction also applies for enabling the interrupts
system i.e. no interrupt requests are acknowledged until the instruction following
the enabling instruction.
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Derivatives
Central Processing Unit (CPU)
External Memory Access Sequences
The effect described here will become noticeable only when watching the external
memory access sequences on the external bus (by means of a Logic Analyzer). Different
pipeline stages can simultaneously put a request on the External Bus Controller (EBC).
The sequence of instructions processed by the CPU may differ from the sequence of the
corresponding external memory accesses performed by the EBC due to the predefined
priority of external memory accesses:
1st
2nd
3rd
Write Data
Fetch Code
Read Data
Initialization of Port Pins
Direction modification of port pins (input or output) become effective only after the
instruction following the modifying instruction. As bit instructions (BSET, BCLR) use
internal read-modify-write sequences which access the entire port, instructions which
modify the port direction should be followed by an instruction that does not access the
same port (see example below).
PORT_INIT_WRONG:
BSET
DP8.3
BSET
P8.2
PORT_INIT_RIGHT:
BSET
DP8.3
NOP
BSET
P8.2
;change direction of P8.3 to output
;P8.3 is still input,
;rd-mod-wr reads pin P8.3
;change direction of P8.3 to output
;any instruction not accessing port 8
;P8.3 is now output,
;rd-mod-wr reads P8.3’s output latch
Note: Special attention must be paid to interrupt service routines that modify the same
port as the software they have interrupted.
Changing the System Configuration
The instruction following an instruction that changes the system configuration via register
SYSCON (e.g. the mapping of the internal ROM, segmentation, stack size) cannot use
the new resources (e.g. ROM or stack). In these cases, an instruction which does not
access these resources should be inserted. Code accesses to the new ROM area are
possible only after an absolute branch to this area.
Note: As a rule, instructions that change ROM mapping should be executed from
internal RAM or external memory.
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Derivatives
Central Processing Unit (CPU)
BUSCON/ADDRSEL
The instruction following an instruction that changes the properties of an external
address area cannot access operands within the new area. In these cases, an instruction
that does not access this address area should be inserted. Code accesses to the new
address area should be made after an absolute branch to this area.
Note: As a rule, instructions that change external bus properties should not be executed
from the respective external memory area.
Timing
Instruction pipelining generally reduces the average instruction processing time
significantly (from four to one machine cycles). However, there are some rare cases in
which a particular pipeline situation causes the processing time for a single instruction to
be extended either by one-half or by one machine cycle. Although this additional time
represents only a tiny part of the total program execution time, it might be beneficial to
avoid these pipeline-caused time delays in time-critical program modules.
Section 4.3 below provides a general execution time description and some hints on
optimizing time-critical program parts with regard to such pipeline-caused timing issues.
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Derivatives
Central Processing Unit (CPU)
4.3
Bit-Handling and Bit-Protection
The C164CM provides several mechanisms for bit manipulation. These mechanisms
either manipulate software flags within the internal RAM, control on-chip peripherals via
control bits in their respective SFRs, or control IO functions via port pins.
The instructions BSET, BCLR, BAND, BOR, BXOR, BMOV, BMOVN explicitly set or
clear specific bits. The instructions BFLDL and BFLDH allow manipulation of up to 8 bits
of a specific byte at one time. The instructions JBC and JNBS implicitly clear or set the
specified bit when the jump is taken. The instructions JB and JNB (also conditional jump
instructions that refer to flags) evaluate the specified bit to determine if the jump is to be
taken.
Note: Bit operations on undefined bit locations will always read a bit value of ‘0’, while
the write access will not affect the respective bit location.
All instructions that manipulate single bits or bit groups internally use a read-modify-write
sequence that accesses the whole word containing the specified bit(s).
This method has several consequences:
• Bits can be modified only within the internal address areas (internal RAM and SFRs).
External locations cannot be used with bit instructions.
The upper 256 bytes of the SFR area, the ESFR area, and the internal RAM are
bit-addressable (see Chapter 3); so, the register bits located within those respective
sections can be manipulated directly using bit instructions. The other SFRs must be
accessed byte/word wise.
Note: All GPRs are bit-addressable independently from the allocation of the register
bank via the Context Pointer (CP). Even GPRs which are allocated to
non-bit-addressable RAM locations provide this feature.
• The read-modify-write approach may be critical with hardware-affected bits. In these
cases, the hardware may change specific bits while the read-modify-write operation is
in progress; thus, the writeback would overwrite the new bit value generated by the
hardware. The solution is provided by either the implemented hardware protection
(see below) or through special programming (see Section 4.2).
Protected bits are not changed during the read-modify-write sequence, such as when
hardware sets an interrupt request flag between the read and the write of the
read-modify-write sequence. The hardware protection logic guarantees that only the
intended bit(s) is/are affected by the write-back operation.
Note: If a conflict occurs between a bit manipulation generated by hardware and an
intended software access, the software access has priority and determines the
final value of the respective bit.
A summary of the protected bits implemented in the C164CM can be found at the end of
Chapter 2.
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Derivatives
Central Processing Unit (CPU)
4.4
Instruction State Times
The time to execute an instruction depends primarily on where the instruction is fetched
from, and where the possible operands are read from or written to. The fastest
processing mode of the C164CM is execution of a program fetched from the internal
code memory. In this case, most of the instructions can be processed within just one
machine cycle, which is also the general minimum execution time.
All external memory accesses are performed by the C164CM’s on-chip External Bus
Controller (EBC), which works in parallel with the CPU.
This section provides a very condensed summary of the execution times. A detailed
description of the execution times for the various instructions and the specific exceptions
can be found in the “C166 Family Instruction Set Manual”.
Table 4-1 shows the minimum execution times required to process a C164CM
instruction fetched from the internal code memory, the internal RAM, or from external
memory. These execution times apply to most of the C164CM instructions - except for
some of the branches, the multiplication, the division, and a special move instruction. In
case of internal ROM program execution, there is no execution time dependency on the
instruction length except for some special branch situations. The numbers in the table
are in units of CPU clock cycles and assume no waitstates.
Table 4-1
Minimum Execution Times
Instruction Fetch
Memory Area
Word Operand Access
Word
Instruction
Doubleword
Instruction
Read from
Write to
Internal code memory
2
2
2
---
Internal RAM
6
8
0/1
0
16-bit Demux Bus
2
4
2
2
16-bit Mux Bus
3
6
3
3
8-bit Demux Bus
4
8
4
4
8-bit Mux Bus
6
12
6
6
Execution from the internal RAM provides flexibility in terms of loadable and modifyable
code on the account of execution time.
Execution from external memory is heavily dependent on the selected bus mode and the
programming of the bus cycles (waitstates).
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Derivatives
Central Processing Unit (CPU)
The operand and instruction accesses listed below can extend the execution time of an
instruction:
•
•
•
•
•
•
•
Internal code memory operand reads (same for byte and word operand reads)
Internal RAM operand reads via indirect addressing modes
Internal SFR operand reads immediately after writing
External operand reads
External operand writes
Jumps to non-aligned double word instructions in the internal ROM space
Testing Branch Conditions immediately after PSW writes
4.5
CPU Special Function Registers
The core CPU requires a set of Special Function Registers (SFRs) to maintain the
system state information, to supply the ALU with register-addressable constants, and to
control system and bus configuration, multiply and divide ALU operations, code memory
segmentation, data memory paging, and accesses to the General Purpose Registers
and the System Stack.
The access mechanism for these SFRs in the CPU core is identical to the access
mechanism for any other SFR. Since all SFRs can be controlled simply by means of any
instruction capable of addressing the SFR memory space, significant flexibility has been
gained without the need to create a set of system-specific instructions.
Note, however, that there are user access restrictions for some of the CPU core SFRs
to ensure proper processor operations. The Instruction Pointer (IP) and Code Segment
Pointer (CSP) cannot be accessed directly at all. They can be changed only indirectly via
branch instructions.
The PSW, SP, and MDC registers can be modified not only explicitly by the programmer,
but also implicitly by the CPU during normal instruction processing. Note that any explicit
write request (via software) to an SFR supersedes a simultaneous modification by
hardware of the same register.
Note: Any write operation to a single byte of an SFR clears the non-addressed
complementary byte within the specified SFR.
Non-implemented (reserved) SFR bits cannot be modified and will always supply
a read value of ‘0’.
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Derivatives
Central Processing Unit (CPU)
System Configuration Register SYSCON
This bit-addressable register provides general system configuration and control
functions. The reset value for register SYSCON depends on the state of the PORT0 pins
during reset (see hardware effectable bits).
SYSCON
System Control Register
15
14
13
STKSZ
rw
12
11
SFR (FF12H/89H)
10
ROM SGT ROM
S1 DIS EN
rw
rw
rwh
Reset Value: 0XX0H
9
8
7
6
5
-
CLK
EN
-
-
-
-
rw
-
-
-
4
3
2
1
BD
VISIOWD RST
DIS EN XPEN BLE
rwh rw
rw
rw
0
-
Bit
Function
VISIBLE
Visible Mode Control
0:
Accesses to XBUS peripherals are done internally
1:
XBUS peripheral accesses are made visible on the external pins
XPEN
XBUS Peripheral Enable Bit
0:
Accesses to the on-chip X-Peripherals and their functions are
disabled
1:
The on-chip X-Peripherals are enabled and can be accessed
BDRSTEN
Bidirectional Reset Enable Bit
0:
Pin RSTIN is an input only
1:
Pin RSTIN is pulled low during the internal reset sequence
after any reset
OWDDIS
Oscillator Watchdog Disable Bit
0:
The on-chip oscillator watchdog is enabled and active
1:
The on-chip oscillator watchdog is disabled and the CPU clock is
always fed from the oscillator input
CLKEN
System Clock Output Enable (CLKOUT)
0:
CLKOUT disabled: pin may be used for general purpose IO or
for signal FOUT
1:
CLKOUT enabled: pin outputs the system clock signal
ROMEN
Internal ROM Enable (Set according to pin EA during reset)
0:
Internal program memory disabled,
accesses to the ROM area use the external bus
1:
Internal program memory enabled
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Derivatives
Central Processing Unit (CPU)
Bit
Function
SGTDIS
Segmentation Disable/Enable Control
0:
Segmentation enabled
(CSP is saved/restored during interrupt entry/exit)
1:
Segmentation disabled (Only IP is saved/restored)
ROMS1
Internal ROM Mapping
0:
Internal ROM area mapped to segment 0 (00’0000H … 00’7FFFH)
1:
Internal ROM area mapped to segment 1 (01’0000H … 01’7FFFH)
STKSZ
System Stack Size
Selects the size of the system stack (in the internal RAM)
from 32 to 512 words
Note: Register SYSCON cannot be changed after execution of the EINIT instruction.
The function of bits VISIBLE, ROMEN, and ROMS1 is described in more detail in
Chapter 9.
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Derivatives
Central Processing Unit (CPU)
System Clock Output Enable (CLKEN)
The system clock output function is enabled by setting bit CLKEN in register SYSCON
to ‘1’. If enabled, port pin P20.8 takes on its alternate function as CLKOUT output pin.
The clock output is a 50% duty cycle clock (except for direct drive operation where
CLKOUT reflects the clock input signal, and for slowdown operation where CLKOUT
mirrors the CPU clock signal) whose frequency equals the CPU operating frequency
(fOUT = fCPU).
Note: The output driver of port pin P20.8 is switched on automatically when the CLKOUT
function is enabled. The port direction bit is disregarded.
After reset, the clock output function is disabled (CLKEN = ‘0’).
In emulation mode, the CLKOUT function is enabled automatically.
Segmentation Disable/Enable Control (SGTDIS)
Bit SGTDIS allows selection of either the segmented or non-segmented memory mode.
In non-segmented memory mode (SGTDIS = ‘1’), it is assumed that the code address
space is restricted to 64 KBytes (segment 0); thus, 16 bits are sufficient to represent all
code addresses. For implicit stack operations (CALL or RET), the CSP register is totally
ignored and only the IP is saved to and restored from the stack.
In segmented memory mode (SGTDIS = ‘0’) it is assumed that the entire address
space is available for instructions. For implicit stack operations (CALL or RET) the CSP
register and the IP are saved to and restored from the stack. After reset, the segmented
memory mode is selected.
Note: Bit SGTDIS controls whether the CSP register is pushed onto the system stack in
addition to the IP register before an interrupt service routine is entered, and it is
repopped when the interrupt service routine is left again.
System Stack Size (STKSZ)
This bitfield defines the size of the physical system stack located in the internal RAM of
the C164CM. An area of 32 … 512 words or all of the internal RAM may be dedicated to
the system stack. A so-called “circular stack” mechanism allows use of a bigger virtual
stack than this dedicated RAM area.
These techniques and the encoding of bitfield STKSZ are described in more detail in
Chapter 22.
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Derivatives
Central Processing Unit (CPU)
Processor Status Word PSW
This bit-addressable register reflects the current state of the microcontroller. Two groups
of bits represent the current ALU status, and the current CPU interrupt status. A separate
bit (USR0) within register PSW is provided as a general purpose user flag.
PSW
Program Status Word
15
14
13
12
SFR (FF10H/88H)
11
10
9
8
7
ILVL
IEN
-
-
-
-
rwh
rw
-
-
-
-
Reset Value: 0000H
6
5
USR0 MUL
IP
rw
rwh
4
3
2
1
0
E
Z
V
C
N
rwh
rwh
rwh
rwh
rwh
Bit
Function
N
Negative Result
Set, when the result of an ALU operation is negative.
C
Carry Flag
Set, when the result of an ALU operation produces a carry bit.
V
Overflow Result
Set, when the result of an ALU operation produces an overflow.
Z
Zero Flag
Set, when the result of an ALU operation is zero.
E
End of Table Flag
Set, when the source operand of an instruction is 8000H or 80H.
MULIP
Multiplication/Division In Progress
0: There is no multiplication/division in progress.
1: A multiplication/division has been interrupted.
USR0
User General Purpose Flag
May be used by the application software.
ILVL, IEN
Interrupt Control Fields
Define the response to interrupt requests. (Described in Chapter 5)
ALU Status (N, C, V, Z, E, MULIP)
The condition flags (N, C, V, Z, E) within the PSW indicate the ALU status after the most
recently performed ALU operation. They are set by most of the instructions according to
specific rules which depend on the ALU or data movement operation performed by an
instruction.
After execution of an instruction which explicitly updates the PSW register, the condition
flags cannot be interpreted as described below because any explicit write to the PSW
User’s Manual
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Derivatives
Central Processing Unit (CPU)
register supersedes the condition flag values which are implicitly generated by the CPU.
Explicitly reading the PSW register supplies a read value which represents the state of
the PSW register after execution of the immediately preceding instruction.
Note: After reset, all of the ALU status bits are cleared.
N-Flag: For most of the ALU operations, the N-flag is set to ‘1’, if the most significant bit
of the result contains a ‘1’; otherwise, it is cleared. In the case of integer operations, the
N-flag can be interpreted as the sign bit of the result (negative: N = ‘1’, positive: N = ‘0’).
Negative numbers are always represented as the 2’s complement of the corresponding
positive number. The range of signed numbers extends from ‘-8000H’ to ‘+7FFFH’ for the
word data type, or from ‘-80H’ to ‘+7FH’ for the byte data type. For Boolean bit operations
with only one operand, the N-flag represents the previous state of the specified bit. For
Boolean bit operations with two operands, the N-flag represents the logical XORing of
the two specified bits.
C-Flag: After an addition, the C-flag indicates that a carry from the most significant bit of
the specified word or byte data type has been generated. After a subtraction or a
comparison, the C-flag indicates a borrow which represents the logical negation of a
carry for the addition.
This means that the C-flag is set to ‘1’, if no carry from the most significant bit of the
specified word or byte data type has been generated during a subtraction, which is
performed internally by the ALU as a 2’s complement addition, and, the C-flag is cleared
when this complement addition caused a carry.
The C-flag is always cleared for logical, multiply and divide ALU operations, because
these operations cannot cause a carry.
For shift and rotate operations, the C-flag represents the value of the bit shifted out last.
If a shift count of 0 is specified, the C-flag will be cleared. The C-flag is also cleared for
a prioritize ALU operation, because a ‘1’ is never shifted out of the MSB during the
normalization of an operand.
For Boolean bit operations with only one operand, the C-flag is always cleared. For
Boolean bit operations with two operands, the C-flag represents the logical ANDing of
the two specified bits.
V-Flag: For addition, subtraction, and 2’s complementation, the V-flag is always set to
‘1’ if the result overflows the maximum range of signed numbers which are representable
by either 16 bits for word operations (‘-8000H’ to ‘+7FFFH’), or by 8 bits for byte
operations (‘-80H’ to ‘+7FH’). Otherwise, the V-flag is cleared. Note that the result of an
integer addition, integer subtraction, or 2’s complement is not valid if the V-flag indicates
an arithmetic overflow.
For multiplication and division, the V-flag is set to ‘1’ if the result cannot be represented
in a word data type; otherwise, it is cleared. Note that a division by zero will always cause
an overflow. In contrast to the result of a division, the result of a multiplication is valid
whether or not the V-flag is set to ‘1’.
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Derivatives
Central Processing Unit (CPU)
Because logical ALU operations cannot produce an invalid result, the V-flag is cleared
by these operations.
The V-flag is also used as a ‘Sticky Bit’ for rotate right and shift right operations. With
only using the C-flag, a rounding error caused by a shift right operation can be estimated
up to a quantity of one half of the LSB of the result. In conjunction with the V-flag, the
C-flag allows evaluation of the rounding error with a finer resolution (see Table 4-2).
For Boolean bit operations with only one operand, the V-flag is always cleared. For
Boolean bit operations with two operands, the V-flag represents the logical ORing of the
two specified bits.
Table 4-2
Shift Right Rounding Error Evaluation
C-Flag
V-Flag
Rounding Error Quantity
0
0
1
1
0
1
0
1
0<
No rounding error
Rounding error
Rounding error
Rounding error
< 1/2 LSB
= 1/2 LSB
> 1/2 LSB
Z-Flag: The Z-flag is normally set to ‘1’ if the result of an ALU operation equals zero,
otherwise it is cleared.
For the addition and subtraction with carry, the Z-flag is only set to ‘1’, if the Z-flag already
contains a ‘1’ and the result of the current ALU operation additionally equals zero. This
mechanism is provided to support multiple precision calculations.
For Boolean bit operations with only one operand, the Z-flag represents the logical
negation of the previous state of the specified bit. For Boolean bit operations with two
operands, the Z-flag represents the logical NORing of the two specified bits. For the
prioritized ALU operation, the Z-flag indicates whether the second operand was zero.
E-Flag: The E-flag can be altered by instructions which perform ALU or data movement
operations. The E-flag is cleared by those instructions which cannot be reasonably used
for table search operations. In all other cases, the E-flag is set depending on the value
of the source operand to signify whether the end of a search table is reached or not. If
the value of the source operand of an instruction equals the lowest negative number
which is representable by the data format of the corresponding instruction (‘8000H’ for
the word data type, or ‘80H’ for the byte data type), the E-flag is set to ‘1’; otherwise, it is
cleared.
MULIP-Flag: The MULIP-flag will be set to ‘1’ by hardware upon entrance into an
interrupt service routine when a multiply or divide ALU operation was interrupted before
completion. Depending on the state of the MULIP bit, the hardware decides whether or
not a multiplication or division must be continued after the end of an interrupt service.
The MULIP bit is overwritten with the contents of the stacked MULIP-flag when the
return-from-interrupt-instruction (RETI) is executed. This normally means that the
MULIP-flag is cleared again afterwards.
User’s Manual
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Derivatives
Central Processing Unit (CPU)
Note: The MULIP flag is part of the task environment! When the interrupting service
routine does not return to the interrupted multiply/divide instruction (as in the case
of a task scheduler which switches between independent tasks), the MULIP flag
must be saved as part of the task environment and must be updated accordingly
for the new task before this task is entered.
CPU Interrupt Status (IEN, ILVL)
The Interrupt Enable bit allows interrupts to be globally enabled (IEN = ‘1’) or disabled
(IEN = ‘0’). The four-bit Interrupt Level field (ILVL) specifies the priority of the current
CPU activity. The interrupt level is updated by hardware on entry into an interrupt service
routine, but it can also be modified via software to prevent other interrupts from being
acknowledged. If an interrupt level ‘15’ has been assigned to the CPU, it has the highest
possible priority; thus, the current CPU operation cannot be interrupted except by
hardware traps or external non-maskable interrupts. For details refer to Chapter 5.
After reset, all interrupts are globally disabled, and the lowest priority (ILVL = 0) is
assigned to the initial CPU activity.
Instruction Pointer IP
This register determines the 16-bit intra-segment address of the currently fetched
instruction within the code segment selected by the CSP register. The IP register is not
mapped into the C164CM’s address space; thus, it is not directly accessible by the
programmer. However, the IP can be modified indirectly via the stack by means of a
return instruction.
The IP register is implicitly updated by the CPU for branch instructions and after
instruction fetch operations.
IP
Instruction Pointer
15
14
13
12
- - - (- - - -/- -)
11
10
9
8
7
Reset Value: 0000H
6
5
4
3
2
1
0
ip
(r)(w)h
Bit
Function
ip
Specifies the intra-segment offset from which the current instruction is to
be fetched. IP refers to the current segment <SEGNR>.
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Derivatives
Central Processing Unit (CPU)
Code Segment Pointer CSP
This non-bit addressable register selects the code segment being used at run-time to
access instructions. The lower 8 bits of register CSP select one of up to 256 segments
of 64 KBytes each; the upper 8 bits are reserved for future use.
CSP
Code Segment Pointer
SFR (FE08H/04H)
7
6
Reset Value: 0000H
15
14
13
12
11
10
9
8
5
4
3
-
-
-
-
-
-
-
-
SEGNR
-
-
-
-
-
-
-
-
rh
2
1
0
Bit
Function
SEGNR
Segment Number
Specifies the code segment from which the current instruction is to be
fetched. SEGNR is ignored when segmentation is disabled.
Code memory addresses are generated by directly extending the 16-bit contents of the
IP register by the contents of the CSP register, as shown in Figure 4-5.
For non-segmented memory mode, the content of this register is not significant because
all code accesses are automatically restricted to segment 0.
Note: The CSP register can only be read but cannot be written by data operations. It is,
however, modified either directly by means of the JMPS and CALLS instructions,
or indirectly via the stack by means of the RETS and RETI instructions.
Upon the acceptance of an interrupt or the execution of a software TRAP
instruction, the CSP register is set automatically to zero.
User’s Manual
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Derivatives
Central Processing Unit (CPU)
Figure 4-5
Addressing via the Code Segment Pointer
Note: When segmentation is disabled, the IP value is used directly as the 16-bit address.
User’s Manual
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Derivatives
Central Processing Unit (CPU)
Data Page Pointers DPP0, DPP1, DPP2, DPP3
These four non-bit addressable registers select up to four different data pages to be
active simultaneously at run-time. The lower 10 bits of each DPP register select one of
the 1024 possible 16-KByte data pages; the upper 6 bits are reserved for future use. The
DPP registers allow access to the entire memory space in pages of 16 KBytes each.
DPP0
Data Page Pointer 0
SFR (FE00H/00H)
15
14
13
12
11
10
-
-
-
-
-
-
DPP0PN
-
-
-
-
-
-
rw
DPP1
Data Page Pointer 1
9
8
7
6
Reset Value: 0000H
5
4
SFR (FE02H/01H)
8
7
6
14
13
12
11
10
-
-
-
-
-
-
DPP1PN
-
-
-
-
-
-
rw
5
4
SFR (FE04H/02H)
8
7
6
14
13
12
11
10
-
-
-
-
-
-
DPP2PN
-
-
-
-
-
-
rw
5
4
SFR (FE06H/03H)
8
7
14
13
12
11
10
-
-
-
-
-
-
DPP3PN
-
-
-
-
-
-
rw
4-22
6
0
3
2
1
0
3
2
1
0
Reset Value: 0003H
15
User’s Manual
9
1
Reset Value: 0002H
15
DPP3
Data Page Pointer 3
9
2
Reset Value: 0001H
15
DPP2
Data Page Pointer 2
9
3
5
4
3
2
1
0
V1.0, 2002-02
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Derivatives
Central Processing Unit (CPU)
Bit
Function
DPPxPN
Data Page Number of DPPx
Specifies the data page selected via DPPx. Only the least significant two
bits of DPPx are significant, when segmentation is disabled.
The DPP registers are implicitly used whenever data accesses to any memory location
are made via indirect or direct long 16-bit addressing modes (except for override
accesses via EXTended instructions and PEC data transfers). After reset, the Data Page
Pointers are initialized in such a way that all indirect or direct long 16-bit addresses result
in identical 18-bit addresses. This allows access to data pages 3 … 0 within segment 0
as shown in Figure 4-6. If the user does not want to use data paging, no further action
is required.
Data paging is performed by concatenating the lower 14 bits of an indirect or direct long
16-bit address with the contents of the DPP register selected by the upper two bits of the
16-bit address. The contents of the selected DPP register specify one of the 1024
possible data pages. This data page base address together with the 14-bit page offset
forms the physical 24-bit address (the selectable part is driven to the address pins).
In non-segmented memory mode, only the two least significant bits of the implicitly
selected DPP register are used to generate the physical address. Thus, extreme care
should be taken when changing the content of a DPP register if a non-segmented
memory model is selected to avoid unexpected results.
A DPP register can be updated via any instruction capable of modifying an SFR.
Note: Due to the internal instruction pipeline, a new DPP value is not yet usable for the
operand address calculation of the instruction immediately following the
instruction which updates the DPP register.
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Derivatives
Central Processing Unit (CPU)
16-Bit Data Address
15 14
0
1023
1022
1021
DPP Registers
3
DPP3-11
2
DPP2-10
1
DPP1-01
0
DPP0-00
14-Bit
Intra-Page Address
(concatenated with
content of DPPx).
Affer reset or with segmentation disabled the DPP registers select data pages 3...0.
All of the internal memory is accessible in these cases.
MCA02264
Figure 4-6
User’s Manual
Addressing via the Data Page Pointers
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Derivatives
Central Processing Unit (CPU)
Context Pointer CP
This non-bit addressable register is used to select the current register context. This
means that the CP register value determines the address of the first General Purpose
Register (GPR) within the current register bank of up to 16 wordwide and/or bytewide
GPRs.
CP
Context Pointer
SFR (FE10H/08H)
11
10
9
8
7
6
Reset Value: FC00H
15
14
13
12
5
4
3
2
1
0
1
1
1
1
cp
0
r
r
r
r
rw
r
Bit
Function
cp
Modifiable portion of register CP
Specifies the (word) base address of the current register bank.
When writing a value to register CP with bits CP.11 … CP.9 = ‘000’, bits
CP.11 … CP.10 are set to ‘11’ by hardware. In all other cases, all bits of
the bit field “cp” receive the written value.
Note: It is the user’s responsibility to ensure that the physical GPR address specified via
CP register plus short GPR address is always an internal RAM location. If this
condition is not met, unexpected results may occur.
• Do not set CP below the IRAM start address, i.e. 00’FA00H/00’F600H/00’F200H
(referring to an IRAM size of 1/2/3 KByte)
• Do not set CP above 00’FDFEH
• Be careful using the upper GPRs with CP above 00’FDE0H
The CP register can be updated via any instruction capable of modifying an SFR.
Note: Due to the internal instruction pipeline, a new CP value is not yet usable for GPR
address calculations of the instruction immediately following the instruction which
updated the CP register.
The Switch Context instruction (SCXT) allows saving the content of register CP on the
stack and updating it with a new value in only one machine cycle.
User’s Manual
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Derivatives
Central Processing Unit (CPU)
Figure 4-7
Register Bank Selection via Register CP
Several addressing modes use register CP implicitly for address calculations. The
addressing modes identified below are described in Chapter 24.
Short 4-Bit GPR Addresses (mnemonic: Rw or Rb) specify an address relative to the
memory location specified by the contents of the CP register, i.e. the base of the current
register bank.
Depending on whether a relative word (Rw) or byte (Rb) GPR address is specified, the
short 4-bit GPR address is either multiplied by two or not before it is added to the
content of register CP (see Figure 4-8). Thus, both byte and word GPR accesses are
possible.
GPRs used as indirect address pointers are always accessed wordwise. For some
instructions, only the first four GPRs can be used as indirect address pointers. These
GPRs are specified via short 2-bit GPR addresses. The respective physical address
calculation is identical to that for the short 4-bit GPR addresses.
Short 8-Bit Register Addresses (mnemonic: reg or bitoff) within a range from F0H to
FFH interpret the four least significant bits as short 4-bit GPR address; the four most
significant bits are ignored. The respective physical GPR address calculation is identical
to that for the short 4-bit GPR addresses. For single bit accesses on a GPR, the GPR’s
word address is calculated as just described, but the position of the bit within the word is
specified by a separate additional 4-bit value.
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Derivatives
Central Processing Unit (CPU)
Specified by reg or bitoff
Context
Pointer
4-Bit GPR
Address
1111
Internal
RAM
*2
Control
+
Must be
within the
internal
RAM area
GPRs
For byte GPR
accesses
Figure 4-8
For word GPR
accesses
MCD02005
Implicit CP Use by Short GPR Addressing Modes
Stack Pointer SP
This non-bit addressable register is used to point to the top of the internal system stack
(TOS). The SP register is pre-decremented whenever data is to be pushed onto the
stack, and it is post-incremented whenever data is to be popped from the stack. Thus,
the system stack grows from higher toward lower memory locations.
Because the least significant bit of register SP is tied to ‘0’ and bits 15 through 12 are
tied to ‘1’ by hardware, the SP register can contain values from F000H to FFFEH only.
This allows access to a physical stack within the internal RAM of the C164CM. A virtual
stack (usually bigger) can be implemented via software. This mechanism is supported
by registers STKOV and STKUN (see respective descriptions below).
The SP register can be updated via any instruction, which is capable of modifying an SFR.
Note: Due to the internal instruction pipeline, a POP or RETURN instruction must not
immediately follow an instruction which updated the SP register.
SP
Stack Pointer Register
11
SFR (FE12H/09H)
10
9
8
7
6
Reset Value: FC00H
15
14
13
12
5
1
1
1
1
sp
0
r
r
r
r
rwh
r
Bit
Function
sp
Modifiable portion of register SP
Specifies the top of the internal system stack.
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Derivatives
Central Processing Unit (CPU)
Stack Overflow Pointer STKOV
This non-bit addressable register is compared against the SP register after each
operation which pushes data onto the system stack (e.g. PUSH and CALL instructions
or interrupts) and after each subtraction from the SP register. If the content of the SP
register is less than the content of the STKOV register, a stack overflow hardware trap
will occur.
Because the least significant bit of register STKOV is tied to ‘0’ and bits 15 through 12
are tied to ‘1’ by hardware, the STKOV register can contain values from F000H to FFFEH
only.
STKOV
Stack Overflow Reg.
SFR (FE14H/0AH)
15
14
13
12
11
10
9
8
7
6
1
1
1
1
stkov
r
r
r
r
rw
Reset Value: FA00H
5
4
Bit
Function
stkov
Modifiable portion of register STKOV
Specifies the lower limit of the internal system stack.
3
2
1
0
0
The Stack Overflow Trap (entered when (SP) < (STKOV)) may be used in two different
ways:
• Fatal error indication treats the stack overflow as a system error through the
associated trap service routine. Under these circumstances data in the bottom of the
stack may have been overwritten by the status information stacked upon servicing the
stack overflow trap.
• Automatic system stack flushing allows to use the system stack as a ‘Stack Cache’
for a bigger external user stack. In this case register STKOV should be initialized to a
value, which represents the desired lowest Top of Stack address plus 12 according to
the selected maximum stack size. This considers the worst case that will occur, when
a stack overflow condition is detected just during entry into an interrupt service routine.
Then, six additional stack word locations are required to push IP, PSW, and CSP for
both the interrupt service routine and the hardware trap service routine.
More details about the stack overflow trap service routine and virtual stack management
are given in Chapter 24.
User’s Manual
4-28
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C164CM/C164SM
Derivatives
Central Processing Unit (CPU)
Stack Underflow Pointer STKUN
This non-bit addressable register is compared against the SP register after each
operation which pops data from the system stack (e.g. POP and RET instructions) and
after each addition to the SP register. If the content of the SP register is greater than the
content of the STKUN register, a stack underflow hardware trap will occur.
Because the least significant bit of register STKUN is tied to ‘0’ and bits 15 through 12
are tied to ‘1’ by hardware, the STKUN register can contain values from F000H to FFFEH
only.
STKUN
Stack Underflow Reg.
SFR (FE16H/0BH)
11
10
9
8
7
6
Reset Value: FC00H
15
14
13
12
5
4
3
1
1
1
1
stkun
0
r
r
r
r
rw
r
Bit
Function
stkun
Modifiable portion of register STKUN
Specifies the upper limit of the internal system stack.
2
1
0
The Stack Underflow Trap (entered when (SP) > (STKUN)) may be used in two different
ways:
• Fatal error indication treats the stack underflow as a system error through the
associated trap service routine.
• Automatic system stack refilling allows to use the system stack as a ‘Stack Cache’
for a bigger external user stack. In this case register STKUN should be initialized to a
value, which represents the desired highest Bottom of Stack address.
More details about the stack underflow trap service routine and virtual stack
management are given in Chapter 24.
Scope of Stack Limit Control
The Stack Limit Control implemented by the register pair STKOV and STKUN detects
cases in which the Stack Pointer SP is moved outside the defined stack area, either by
ADD or SUB instructions or by PUSH or POP operations (explicit or implicit, i.e. CALL or
RET instructions).
This control mechanism is not triggered, i.e. no stack trap is generated, when
• The Stack Pointer SP is directly updated via MOV instructions
• The limits of the stack area (STKOV, STKUN) are changed so that SP is outside the
new limits
User’s Manual
4-29
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C164CM/C164SM
Derivatives
Central Processing Unit (CPU)
Multiply/Divide High Register MDH
This register is part of the 32-bit multiply/divide register which is implicitly used by the
CPU when it performs a multiplication or a division. After a multiplication, this non-bit
addressable register represents the high order 16 bits of the 32-bit result. For long
divisions, the MDH register must be loaded with the high order 16 bits of the 32-bit
dividend before the division is started. After any division, register MDH represents the
16-bit remainder.
MDH
Multiply/Divide High Reg.
15
14
13
12
11
SFR (FE0CH/06H)
10
9
8
7
6
Reset Value: 0000H
5
4
3
2
1
0
mdh
rwh
Bit
Function
mdh
Specifies the high order 16 bits of the 32-bit multiply and divide reg. MD.
Whenever this register is updated via software, the Multiply/Divide Register In Use
(MDRIU) flag in the Multiply/Divide Control register (MDC) is set to ‘1’.
When a multiplication or division is interrupted before its completion and when a new
multiply or divide operation is to be performed within the interrupt service routine, register
MDH must be saved along with registers MDL and MDC to avoid erroneous results.
A detailed description of how to use the MDH register for programming multiply and
divide algorithms can be found in Chapter 22.
User’s Manual
4-30
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Derivatives
Central Processing Unit (CPU)
Multiply/Divide Low Register MDL
This register is part of the 32-bit multiply/divide register, which is implicitly used by the
CPU when it performs a multiplication or a division. After a multiplication, this non-bit
addressable register represents the low order 16 bits of the 32-bit result. For long
divisions, the MDL register must be loaded with the low order 16 bits of the 32-bit
dividend before the division is started. After any division, register MDL represents the
16-bit quotient.
MDL
Multiply/Divide Low Reg.
15
14
13
12
11
SFR (FE0EH/07H)
10
9
8
7
6
Reset Value: 0000H
5
4
3
2
1
0
mdl
rwh
Bit
Function
mdl
Specifies the low order 16 bits of the 32-bit multiply and divide reg. MD.
Whenever this register is updated via software, the Multiply/Divide Register In Use
(MDRIU) flag in the Multiply/Divide Control register (MDC) is set to ‘1’. The MDRIU flag
is cleared, whenever the MDL register is read via software.
When a multiplication or division is interrupted before its completion and when a new
multiply or divide operation is to be performed within the interrupt service routine, register
MDL must be saved along with registers MDH and MDC to avoid erroneous results.
A detailed description of how to use the MDL register for programming multiply and
divide algorithms can be found in Chapter 22.
User’s Manual
4-31
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C164CM/C164SM
Derivatives
Central Processing Unit (CPU)
Multiply/Divide Control Register MDC
This bit addressable 16-bit register is implicitly used by the CPU when it performs a
multiplication or a division. It is used to store the required control information for the
corresponding multiply or divide operation. Register MDC is updated by hardware during
each single cycle of a multiply or divide instruction.
MDC
Multiply/Divide Control Reg.
SFR (FF0EH/87H)
Reset Value: 0000H
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
-
-
-
-
-
-
-
-
!!
!!
!!
MDR
IU
!!
!!
!!
!!
-
-
-
-
-
-
-
-
r(w)h r(w)h r(w)h r(w)h r(w)h r(w)h r(w)h r(w)h
Bit
Function
MDRIU
Multiply/Divide Register In Use
0:
Cleared when register MDL is read via software.
1:
Set when register MDL or MDH is written via software or when
a multiply or divide instruction is executed.
!!
Internal Machine Status
The multiply/divide unit uses these bits to control internal operations.
Never modify these bits without saving and restoring register MDC.
When a division or multiplication was interrupted before its completion and the multiply/
divide unit is required, the MDC register must first be saved along with registers MDH
and MDL (to be able to restart the interrupted operation later). Then it must be cleared
to prepare it for the new calculation. After completion of the new division or multiplication,
the state of the interrupted multiply or divide operation must be restored.
The MDRIU flag is the only portion of the MDC register which might be of interest to the
user. The remaining portions of the MDC register are reserved for dedicated use by the
hardware and should never be modified by the user in any way other than described
above. Otherwise, a correct continuation of an interrupted multiply or divide operation
cannot be guaranteed.
A detailed description of how to use the MDC register for programming multiply and
divide algorithms can be found in Chapter 22.
User’s Manual
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C164CM/C164SM
Derivatives
Central Processing Unit (CPU)
Constant Zeros Register ZEROS
All bits of this bit-addressable register are fixed to ‘0’ by hardware. This register can be
read only. Register ZEROS can be used as a register-addressable constant of all zeros,
i.e. for bit manipulation or mask generation. It can be accessed via any instruction
capable of addressing an SFR.
ZEROS
Zeros Register
SFR (FF1CH/8EH)
Reset Value: 0000H
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
Constant Ones Register ONES
All bits of this bit-addressable register are fixed to ‘1’ by hardware. This register can be
read only. Register ONES can be used as a register-addressable constant of all ones,
for bit manipulation or mask generation. It can be accessed via any instruction capable
of addressing an SFR.
ONES
Ones Register
SFR (FF1EH/8FH)
Reset Value: FFFFH
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
User’s Manual
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C164CM/C164SM
Derivatives
Interrupt and Trap Functions
5
Interrupt and Trap Functions
The architecture of the C164CM supports several mechanisms for fast and flexible
response to service requests from various sources internal or external to the
microcontroller. These mechanisms include: Normal Interrupt Processing, Interrupt
Processing via the Peripheral Event Controller, Trap Functions, and External Interrupt
Processing.
Normal Interrupt Processing
The CPU temporarily suspends current program execution and branches to an interrupt
service routine to service an interrupt requesting device. Current program status (IP,
PSW, also CSP in segmentation mode) is saved on the internal system stack. A
prioritization scheme with 16 priority levels allows the user to specify the order in which
multiple interrupt requests are to be handled.
Interrupt Processing via the Peripheral Event Controller (PEC)
A faster alternative to normal software controlled interrupt processing is servicing an
interrupt requesting device with the C164CM’s integrated Peripheral Event Controller
(PEC). Triggered by an interrupt request, the PEC performs a single word or byte data
transfer between any two locations in segment 0 (data pages 0 through 3) through one
of eight programmable PEC Service Channels. During a PEC transfer, normal program
execution of the CPU is halted for only one instruction cycle. No internal program status
information needs to be saved. The same prioritization scheme is used for PEC service
as for normal interrupt processing. PEC transfers share the two highest priority levels.
Trap Functions
Trap functions are activated in response to special conditions that occur during the
execution of instructions. A trap can also be caused externally by the Non-Maskable
Interrupt pin, NMI. Several hardware trap functions are provided to handle erroneous
conditions and exceptions arising during instruction execution. Hardware traps always
have highest priority and cause immediate system reaction. The software trap function
is invoked by the TRAP instruction that generates a software interrupt for a specified
interrupt vector. For all trap types, current program status is saved on the system stack.
External Interrupt Processing
Although the C164CM does not provide dedicated interrupt pins, it allows connection of
external interrupt sources and provides several mechanisms to react to external events
including standard inputs, non-maskable interrupts, and fast external interrupts. Except
for the non-maskable interrupt and the reset input, these interrupt functions are alternate
port functions.
User’s Manual
5-1
V1.0, 2002-02
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Derivatives
Interrupt and Trap Functions
5.1
Interrupt System Structure
The C164CM provides 32 separate interrupt nodes assignable to 16 priority levels. In
order to support modular and consistent software design techniques, most sources of an
interrupt or PEC request are supplied with a separate interrupt control register and an
interrupt vector. The control register contains the interrupt request flag, the interrupt
enable bit, and the interrupt priority of the associated source. Each source request is
then activated by one specific event, determined by the selected operating mode of the
respective device. For efficient resource usage, multi-source interrupt nodes are also
incorporated. These nodes can be activated by several source requests, such as by
different kinds of errors in the serial interfaces. However, specific status flags which
identify the type of error are implemented in the serial channels’ control registers.
Additional sharing of interrupt nodes is supported via the interrupt subnode control
register ISNC (see Section 5.7).
The C164CM provides a vectored interrupt system. In this system specific vector
locations in the memory space are reserved for the reset, trap, and interrupt service
functions. Whenever a request occurs, the CPU branches to the location that is
associated with the respective interrupt source. This allows direct identification of the
source which caused the request. The only exceptions are the Class B hardware traps,
all of which share the same interrupt vector. The status flags in the Trap Flag Register
(TFR) can then be used to determine which exception caused the trap. For the special
software TRAP instruction, the vector address is specified by the operand field of the
instruction, which is a seven bit trap number.
The reserved vector locations build a jump table in the low end of the C164CM’s address
space (segment 0). The jump table consists of the appropriate jump instructions which
transfer control to the interrupt or trap service routines and which may be located
anywhere within the address space. The entries of the jump table are located at the
lowest addresses in code segment 0 of the address space. Each entry occupies two
words, except for the reset vector and the hardware trap vectors, which occupy four or
eight words. Table 5-1 lists all sources capable of requesting interrupt or PEC service in
the C164CM, the associated interrupt vectors, their locations, and the associated trap
numbers. It also lists the mnemonics of the affected Interrupt Request flags and their
corresponding Interrupt Enable flags. The mnemonics consist of a part which specifies
the respective source, followed by a part which specifies its function (IR = Interrupt
Request flag, IE = Interrupt Enable flag).
Note: Each entry of the interrupt vector table provides room for two word instructions or
one doubleword instruction. The respective vector location results from multiplying
the trap number by 4 (4 bytes per entry).
All interrupt nodes which are currently not used by their associated modules or are
not connected to a module in the actual derivative may be used to generate
software controlled interrupt requests by setting the respective IR flag.
User’s Manual
5-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
Interrupt and Trap Functions
Table 5-1
C164CM Interrupt Nodes and Vectors
Source of Interrupt or
PEC Service Request
Fast External Interrupt 0
Fast External Interrupt 1
Fast External Interrupt 2
Fast External Interrupt 3
GPT1 Timer 2
GPT1 Timer 3
GPT1 Timer 4
A/D Conversion Complete
A/D Overrun Error
ASC0 Transmit
ASC0 Receive
ASC0 Error
SSC Transmit
SSC Receive
SSC Error
CAPCOM Register 16
CAPCOM Register 17
CAPCOM Register 18
CAPCOM Register 19
CAPCOM Register 24
CAPCOM Register 25
CAPCOM Register 26
CAPCOM Register 27
CAPCOM Timer 7
CAPCOM Timer 8
CAPCOM6 Interrupt
CAN
PLL/OWD, RTC
(via ISNC)
ASC0 Transmit Buffer
CAPCOM6 Timer 12
CAPCOM6 Timer 13
CAPCOM6 Emergency
User’s Manual
Request
Flag
CC8IR
CC9IR
CC10IR
CC11IR
T2IR
T3IR
T4IR
ADCIR
ADEIR
S0TIR
S0RIR
S0EIR
SCTIR
SCRIR
SCEIR
CC16IR
CC17IR
CC18IR
CC19IR
CC24IR
CC25IR
CC26IR
CC27IR
T7IR
T8IR
CC6IR
XP0IR
XP3IR
Enable
Flag
CC8IE
CC9IE
CC10IE
CC11IE
T2IE
T3IE
T4IE
ADCIE
ADEIE
S0TIE
S0RIE
S0EIE
SCTIE
SCRIE
SCEIE
CC16IE
CC17IE
CC18IE
CC19IE
CC24IE
CC25IE
CC26IE
CC27IE
T7IE
T8IE
CC6IE
XP0IE
XP3IE
Interrupt
Vector
CC8INT
CC9INT
CC10INT
CC11INT
T2INT
T3INT
T4INT
ADCINT
ADEINT
S0TINT
S0RINT
S0EINT
SCTINT
SCRINT
SCEINT
CC16INT
CC17INT
CC18INT
CC19INT
CC24INT
CC25INT
CC26INT
CC27INT
T7INT
T8INT
CC6INT
XP0INT
XP3INT
Vector
Location
00’0060H
00’0064H
00’0068H
00’006CH
00’0088H
00’008CH
00’0090H
00’00A0H
00’00A4H
00’00A8H
00’00ACH
00’00B0H
00’00B4H
00’00B8H
00’00BCH
00’00C0H
00’00C4H
00’00C8H
00’00CCH
00’00E0H
00’00E4H
00’00E8H
00’00ECH
00’00F4H
00’00F8H
00’00FCH
00’0100H
00’010CH
Trap
Number
18H / 24D
19H / 25D
1AH / 26D
1BH / 27D
22H / 34D
23H / 35D
24H / 36D
28H / 40D
29H / 41D
2AH / 42D
2BH / 43D
2CH / 44D
2DH / 45D
2EH / 46D
2FH / 47D
30H / 48D
31H / 49D
32H / 50D
33H / 51D
38H / 56D
39H / 57D
3AH / 58D
3BH / 59D
3DH / 61D
3EH / 62D
3FH / 63D
40H / 64D
43H / 67D
S0TBIR
T12IR
T13IR
CC6IR
S0TBIE
T12IE
T13IE
CC6IE
S0TBINT
T12INT
T13INT
CC6EINT
00’011CH
00’0134H
00’0138H
00’013CH
47H / 71D
4DH / 77D
4EH / 78D
4FH / 79D
5-3
V1.0, 2002-02
C164CM/C164SM
Derivatives
Interrupt and Trap Functions
Table 5-2 lists the vector locations for hardware traps and the corresponding status flags
in register TFR. It also lists the priorities of trap service for those cases in which more
than one trap condition might be detected within the same instruction. After any reset
(hardware reset, software reset instruction SRST, or reset by watchdog timer overflow)
program execution starts at the reset vector at location 00’0000H. Reset conditions have
priority over every other system activity and, therefore, have the highest priority (trap
priority III).
Software traps may be initiated to any vector location between 00’0000H and 00’01FCH.
A service routine entered via a software TRAP instruction is always executed on the
current CPU priority level which is indicated in bit field ILVL in register PSW. This means
that routines entered via the software TRAP instruction can be interrupted by all
hardware traps or higher level interrupt requests.
Table 5-2
Hardware Trap Summary
Exception Condition
Trap
Flag
Reset Functions
Hardware Reset
Software Reset
Watchdog Timer Overflow
–
Trap
Vector
Vector
Location
Trap
Number
Trap
Prio
RESET
RESET
RESET
00’0000H
00’0000H
00’0000H
00H
00H
00H
III
III
III
Class A Hardware Traps
Non-Maskable Interrupt
Stack Overflow
Stack Underflow
NMI
STKOF
STKUF
NMITRAP 00’0008H
STOTRAP 00’0010H
STUTRAP 00’0018H
02H
04H
06H
II
II
II
Class B Hardware Traps
Undefined Opcode
Protected Instruction Fault
Illegal Word Operand Access
Illegal Instruction Access
Illegal External Bus Access
UNDOPC
PRTFLT
ILLOPA
ILLINA
ILLBUS
BTRAP
BTRAP
BTRAP
BTRAP
BTRAP
00’0028H
00’0028H
00’0028H
00’0028H
00’0028H
0AH
0AH
0AH
0AH
0AH
I
I
I
I
I
Reserved
–
–
[2CH - 3CH] [0BH - 0FH] –
Software Traps
TRAP Instruction
–
–
Current
Any
Any
[00’0000H - [00H - 7FH] CPU
00’01FCH]
Priority
in steps
of 4H
User’s Manual
5-4
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C164CM/C164SM
Derivatives
Interrupt and Trap Functions
Normal Interrupt Processing and PEC Service
During each instruction cycle, one out of all sources requiring PEC or interrupt
processing is selected according to its interrupt priority. This priority of interrupts and
PEC requests is programmable in two levels. Each requesting source can be assigned
to a specific priority. A second level (called “group priority”) allows to specify an internal
order for simultaneous requests from a group of different sources on the same priority
level. At the end of each instruction cycle, the one source request with the highest current
priority will be determined by the interrupt system. This request will then be serviced if
its priority is higher than the current CPU priority in register PSW.
Interrupt System Register Description
Interrupt processing is controlled globally by register PSW through a general interrupt
enable bit (IEN) and the CPU priority field (ILVL). Additionally, the different interrupt
sources are controlled individually by their specific interrupt control registers (… IC).
Thus, the acceptance of requests by the CPU is determined by both the individual
interrupt control registers and by the PSW. PEC services are controlled by the respective
PECCx register and by the source and destination pointers which specify the task of the
respective PEC service channel.
5.1.1
Interrupt Control Registers
All interrupt control registers are organized identically. The lower 8 bits of an interrupt
control register contain complete interrupt status information for the associated source,
which is required for one round of prioritization; the upper 8 bits of the respective register
are reserved. All interrupt control registers are bit-addressable and all bits can be read or
written via software. This allows each interrupt source to be programmed or modified
with just one instruction. When accessing interrupt control registers through instructions
which operate on word data types, their upper 8 bits (15 … 8) will return zeros when
read, and will discard written data.
The layout of the Interrupt Control registers shown below applies to each xxIC register,
where xx represents the mnemonic for the respective source.
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Derivatives
Interrupt and Trap Functions
xxIC
Interrupt Control Register
15
14
13
12
11
(E)SFR (yyyyH/zzH)
10
9
8
7
6
Reset Value: - - 00H
5
4
xxIR xxIE
-
-
-
-
-
-
-
-
rwh
3
2
1
0
ILVL
GLVL
rw
rw
rw
Bit
Function
GLVL
Group Level
Defines the internal order for simultaneous requests of the same priority.
3:
Highest group priority
0:
Lowest group priority
ILVL
Interrupt Priority Level
Defines the priority level for the arbitration of requests.
FH: Highest priority level
0H: Lowest priority level
xxIE
Interrupt Enable Control Bit
(individually enables/disables a specific source)
0:
Interrupt request is disabled
1:
Interrupt Request is enabled
xxIR
Interrupt Request Flag
0:
No request pending
1:
This source has raised an interrupt request
The Interrupt Request Flag is set by hardware whenever a service request from its
respective source occurs. It is cleared automatically upon entry into the interrupt service
routine or upon a PEC service. In the case of PEC service, the Interrupt Request flag
remains set if the COUNT field in register PECCx of the selected PEC channel
decrements to zero. This allows a normal CPU interrupt to respond to a completed PEC
block transfer.
Note: Modifying the Interrupt Request flag via software causes the same effects as if it
had been set or cleared by hardware.
The Interrupt Enable Control Bit determines whether the respective interrupt node
takes part in the arbitration cycles (enabled) or not (disabled). The associated request
flag will be set upon a source request in any case. The occurrence of an interrupt request
can so be polled via xxIR even while the node is disabled.
Note: In this case the interrupt request flag xxIR is not cleared automatically but must be
cleared via software.
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Derivatives
Interrupt and Trap Functions
Interrupt Priority Level and Group Level
The four bits of bit field ILVL specify the priority level of a service request for the
arbitration of simultaneous requests. The priority increases with the numerical value of
ILVL: so, 0000B is the lowest and 1111B is the highest priority level.
When more than one interrupt request on a specific level becomes active at the same
time, the values in the respective bit fields GLVL are used for second level arbitration to
select one request to be serviced. Again, the group priority increases with the numerical
value of GLVL, so 00B is the lowest and 11B is the highest group priority.
Note: All interrupt request sources enabled and programmed to the same priority level
must always be programmed to different group priorities. Otherwise, an incorrect
interrupt vector will be generated.
Upon entry into the interrupt service routine, the priority level of the source that won the
arbitration and whose priority level is higher than the current CPU level, is copied into bit
field ILVL of register PSW after pushing the old PSW contents onto the stack.
The interrupt system of the C164CM allows nesting of up to 15 interrupt service routines
of different priority levels (level 0 cannot be arbitrated).
Interrupt requests programmed to priority levels 15 or 14 (i.e., ILVL = 111XB) will be
serviced by the PEC unless the COUNT field of the associated PECC register contains
zero. In this case, the request will be serviced by normal interrupt processing instead.
Interrupt requests programmed to priority levels 13 through 1 will always be serviced by
normal interrupt processing.
Note: Priority level 0000B is the default level of the CPU. Therefore, a request on level 0
will never be serviced because it can never interrupt the CPU. However, an
enabled interrupt request on level 0000B will terminate the C164CM’s Idle mode
and reactivate the CPU.
For interrupt requests which are to be serviced by the PEC, the associated PEC channel
number is derived from the respective ILVL (LSB) and GLVL (see Figure 5-1). So,
programming a source to priority level 15 (ILVL = 1111B) selects the PEC channel group
7 … 4; programming a source to priority level 14 (ILVL = 1110B) selects the PEC
channel group 3 … 0. The actual PEC channel number is then determined by the group
priority field GLVL.
Simultaneous requests for PEC channels are prioritized according to the PEC channel
number, where channel 0 has lowest and channel 8 has highest priority.
Note: All sources requesting PEC service must be programmed to different PEC
channels. Otherwise, an incorrect PEC channel may be activated.
User’s Manual
5-7
V1.0, 2002-02
C164CM/C164SM
Derivatives
Interrupt and Trap Functions
Interrupt
Control Register
ILVL
GLVL
PEC Control
PEC Channel #
MCA04330
Figure 5-1
Priority Levels and PEC Channels
The Table 5-3 shows in a few examples which action is executed with a given
programming of an interrupt control register.
Table 5-3
Interrupt Priority Examples
Priority Level
Type of Service
COUNT = 00H
COUNT ≠ 00H
1111 11
CPU interrupt,
level 15, group priority 3
PEC service,
channel 7
1111 10
CPU interrupt,
level 15, group priority 2
PEC service,
channel 6
1110 10
CPU interrupt,
level 14, group priority 2
PEC service,
channel 2
1101 10
CPU interrupt,
level 13, group priority 2
CPU interrupt,
level 13, group priority 2
0001 11
CPU interrupt,
level 1, group priority 3
CPU interrupt,
level 1, group priority 3
0001 00
CPU interrupt,
level 1, group priority 0
CPU interrupt,
level 1, group priority 0
0000 XX
No service!
No service!
ILVL
GLVL
Note: Requests on levels 13 … 1 cannot initiate PEC transfers. They are always
serviced by an interrupt service routine: no PECC register is associated and no
COUNT field is checked.
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Derivatives
Interrupt and Trap Functions
Interrupt Control Functions in the PSW
The Processor Status Word (PSW) is functionally divided into two parts: the lower byte
of the PSW basically represents the arithmetic status of the CPU; the upper byte of the
PSW controls the interrupt system of the C164CM and the arbitration mechanism for the
external bus interface.
Note: Pipeline effects must be considered when enabling/disabling interrupt requests
via modifications of register PSW (see Chapter 4).
PSW
Processor Status Word
15
14
13
11
10
9
8
7
ILVL
IEN
-
-
-
-
rwh
rw
-
-
-
-
Bit
12
SFR (FF10H/88H)
6
Reset Value: 0000H
5
USR MUL
0
IP
rw
rwh
4
3
2
1
0
E
Z
V
C
N
rwh
rwh
rwh
rwh
rwh
Function
N, C, V, Z, E, CPU status flags (Described in Chapter 4)
MULIP, USR0 Define the current status of the CPU (ALU, multiplication unit).
IEN
Interrupt Enable Control Bit (globally enables/disables interrupt
requests)
0:
Interrupt requests are disabled
1:
Interrupt requests are enabled
ILVL
CPU Priority Level
Defines the current priority level for the CPU
FH: Highest priority level
0H: Lowest priority level
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Derivatives
Interrupt and Trap Functions
CPU Priority ILVL defines the current level for the operation of the CPU. This bit field
reflects the priority level of the routine currently executed. Upon entry into an interrupt
service routine, this bit field is updated with the priority level of the request being
serviced. The PSW is saved on the system stack before the request is serviced. The
CPU level determines the minimum interrupt priority level which will be serviced. Any
request on the same or a lower level will not be acknowledged.
The current CPU priority level may be adjusted via software to control which interrupt
request sources will be acknowledged.
PEC transfers do not really interrupt the CPU, but rather “steal” a single cycle, so PEC
services do not influence the ILVL field in the PSW.
Hardware traps switch the CPU level to maximum priority (i.e. 15) so no interrupt or PEC
requests will be acknowledged while an exception trap service routine is executed.
Note: The TRAP instruction does not change the CPU level, so software invoked trap
service routines may be interrupted by higher requests.
Interrupt Enable bit IEN globally enables or disables PEC operation and the
acceptance of interrupts by the CPU. When IEN is cleared, no new interrupt requests are
accepted by the CPU. However, requests already in the pipeline at that time will be
processed. When IEN is set to ‘1’, all interrupt sources, which have been individually
enabled by the interrupt enable bits in their associated control registers, are globally
enabled.
Note: Traps are non-maskable and are, therefore, not affected by the IEN bit.
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Derivatives
Interrupt and Trap Functions
5.2
Operation of the PEC Channels
The C164CM’s Peripheral Event Controller (PEC) provides 8 PEC service channels
which move a single byte or word between two locations in segment 0 (data pages
3 … 0). This is the fastest possible interrupt response, and, in many cases is sufficient
to service the respective peripheral request (for example, serial channels, etc.). Each
channel is controlled by a dedicated PEC Channel Counter/Control register (PECCx)
and a pair of pointers for source (SRCPx) and destination (DSTPx) of the data transfer.
The PECC registers control the action performed by the respective PEC channel.
PECCx
PEC Control Reg.
SFR (FECyH/6zH, see Table 5-4)
10
9
8
7
6
5
Reset Value: 0000H
15
14
13
12
11
4
3
-
-
-
-
-
INC
BWT
COUNT
-
-
-
-
-
rw
rw
rw
2
1
0
Bit
Function
COUNT
PEC Transfer Count
Counts PEC transfers and influences the channel’s action (see Table 5-5)
BWT
Byte / Word Transfer Selection
0:
Transfer a Word
1:
Transfer a Byte
INC
Increment Control (Modification of SRCPx or DSTPx)
0 0: Pointers are not modified
0 1: Increment DSTPx by 1 or 2 (BWT)
1 0: Increment SRCPx by 1 or 2 (BWT)
1 1: Reserved. Do not use this combination.
(changed to ‘10’ by hardware)
Table 5-4
PEC Control Register Addresses
Register
Address
PECC0
Register
Address
FEC0H / 60H SFR
PECC4
FEC8H / 64H SFR
PECC1
FEC2H / 61H SFR
PECC5
FECAH / 65H SFR
PECC2
FEC4H / 62H SFR
PECC6
FECCH / 66H SFR
PECC3
FEC6H / 63H SFR
PECC7
FECEH / 67H SFR
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Interrupt and Trap Functions
Byte/Word Transfer bit BWT controls whether a byte or a word is moved during a PEC
service cycle. This selection controls the transferred data size and the increment step for
the modified pointer.
Increment Control field INC controls, whether one of the PEC pointers is incremented
after the PEC transfer. It is not possible to increment both pointers, however. If the
pointers are not modified (INC = ‘00’), the respective channel will always move data from
the same source to the same destination.
Note: The reserved combination ‘11’ is changed to ‘10’ by hardware. However, it is not
recommended to use this combination.
The PEC Transfer Count Field COUNT controls the action of a respective PEC channel.
The content of bit field COUNT selects the action to be taken at the time the request is
activated. COUNT may allow a specified number of PEC transfers, unlimited transfers,
or no PEC service at all.
Table 5-5 summarizes, how the COUNT field, the interrupt requests flag IR, and the
PEC channel action depend on the previous content of COUNT.
Table 5-5
Influence of Bitfield COUNT
Previous
COUNT
Modified
COUNT
IR after
Action of PEC Channel
PEC Service and Comments
FFH
FFH
‘0’
FEH … 02H FDH … 01H ‘0’
Move a Byte/Word
Continuous transfer mode, i.e. COUNT is not
modified
Move a Byte/Word and decrement COUNT
01H
00H
‘1’
Move a Byte/Word
Leave request flag set, which triggers
another request
00H
00H
(‘1’)
No action!
Activate interrupt service routine rather than
PEC channel
The PEC transfer counter allows service of a specified number of requests by the
respective PEC channel, and then (when COUNT reaches 00H) activation of the
interrupt service routine associated with the priority level. After each PEC transfer, the
COUNT field is decremented and the request flag is cleared to indicate that the request
has been serviced.
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Derivatives
Interrupt and Trap Functions
Continuous transfers are selected by the value FFH in bit field COUNT. In this case,
COUNT is not modified and the respective PEC channel services any request until it is
disabled again.
When COUNT is decremented from 01H to 00H after a transfer, the request flag is not
cleared. This generates another request from the same source. When COUNT already
contains the value 00H, the respective PEC channel remains idle and the associated
interrupt service routine is activated instead. This allows choosing whether a level 15 or
14 request should be serviced by the PEC or by the interrupt service routine.
Note: PEC transfers are executed only if their priority level is higher than the CPU level,
that is, only PEC channels 7 … 4 are processed, while the CPU executes on
level 14.
All interrupt request sources that are enabled and programmed for PEC service
should use different channels. Otherwise, only one transfer will be performed for
all simultaneous requests. When COUNT is decremented to 00H, and the CPU is
to be interrupted, an incorrect interrupt vector will be generated.
The source and destination pointers specify the locations between which the data is
to be moved. A pair of pointers (SRCPx and DSTPx) is associated with each of the eight
PEC channels. These pointers do not reside in specific SFRs, but are mapped into the
internal RAM of the C164CM just below the bit-addressable area (see Figure 5-2).
DSTP7
SRCP7
DSTP6
00’FCFE
H
00’FCFC
00’FCFA
SRCP6
00’FCF8
DSTP5
00’FCF6
SRCP5
00’FCF4
DSTP4
00’FCF2
SRCP4
00’FCF0
H
H
H
H
H
H
H
DSTP3
00’FCEE
SRCP3
00’FCEC
DSTP2
00’FCEA
SRCP2
00’FCE8
DSTP1
00’FCE6
SRCP1
00’FCE4
DSTP0
00’FCE2
SRCP0
00’FCE0
H
H
H
H
H
H
H
H
MCA04331
Figure 5-2
User’s Manual
Mapping of PEC Pointers into the Internal RAM
5-13
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Derivatives
Interrupt and Trap Functions
PEC data transfers do not use the data page pointers DPP3 … DPP0. The PEC source
and destination pointers are used as 16-bit intra-segment addresses within segment 0,
so data can be transferred between any two locations within the first four data pages
3 … 0.
The pointer locations for inactive PEC channels may be used for general data storage.
Only the required pointers occupy RAM locations.
Note: If word data transfer is selected for a specific PEC channel (i.e. BWT = ‘0’), the
respective source and destination pointers must both contain a valid word address
which points to an even byte boundary. Otherwise, the Illegal Word Access trap
will be invoked when this channel is used.
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Interrupt and Trap Functions
5.3
Prioritization of Interrupt and PEC Service Requests
Interrupt and PEC service requests from all sources can be enabled so they are
arbitrated and serviced (if they win), or they may be disabled, so their requests are
disregarded and not serviced.
Enabling and disabling interrupt requests may be done via three mechanisms:
• Control Bits
• Priority Level
• ATOMIC and EXTended Instructions
Control Bits allow switching of each individual source “ON” or “OFF” so that it may
generate a request or not. The control bits (xxIE) are located in the respective interrupt
control registers. All interrupt requests may be enabled or disabled generally via bit IEN
in register PSW. This control bit is the “main switch” which selects if requests from any
source are accepted or not.
For a specific request to be arbitrated, the respective source’s enable bit and the global
enable bit must both be set.
The Priority Level automatically selects a certain group of interrupt requests to be
acknowledged and ignores all other requests. The priority level of the source that won
the arbitration is compared against the CPU’s current level and the source is serviced
only if its level is higher than the current CPU level. Changing the CPU level to a specific
value via software blocks all requests on the same or lower level. An interrupt source
assigned to level 0 will be disabled and will never be serviced.
The ATOMIC and EXTend instructions automatically disable all interrupt requests for
the duration of the following 1 … 4 instructions. This is useful for semaphore handling,
for example, and does not require to re-enable the interrupt system after the inseparable
instruction sequence (see Chapter 22).
Interrupt Class Management
An interrupt class covers a set of interrupt sources with the same importance, i.e. the
same priority from the system’s viewpoint. Interrupts of the same class must not interrupt
each other. The C164CM supports this function with two features:
Classes with up to four members can be established by using the same interrupt priority
(ILVL) and assigning a dedicated group level (GLVL) to each member. This functionality
is built-in and handled automatically by the interrupt controller.
Classes with more than four members can be established by using a number of adjacent
interrupt priorities (ILVL) and the respective group levels (four per ILVL). Each interrupt
service routine within this class sets the CPU level to the highest interrupt priority within
the class. All requests from the same or any lower level are blocked now, i.e. no request
of this class will be accepted.
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Derivatives
Interrupt and Trap Functions
The example shown below establishes 3 interrupt classes which cover 2 or 3 interrupt
priorities, depending on the number of members in a class. A level 6 interrupt disables
all other sources in class 2 by changing the current CPU level to 8, which is the highest
priority (ILVL) in class 2. Class 1 requests or PEC requests are still serviced, in this case.
In this way, the 24 interrupt sources (excluding PEC requests) are assigned to 3 classes
of priority rather than to 7 different levels, as the hardware support would do.
Table 5-6
ILVL
(Priority)
Software Controlled Interrupt Classes (Example)
GLVL
3
2
1
Interpretation
0
15
PEC service on up to 8 channels
14
13
12
X
11
X
X
X
X
Interrupt Class 1
5 sources on 2 levels
Interrupt Class 2
9 sources on 3 levels
10
9
8
X
X
X
X
7
X
X
X
X
6
X
5
X
X
X
X
4
X
Interrupt Class 3
5 sources on 2 levels
3
2
1
0
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No service!
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Derivatives
Interrupt and Trap Functions
5.4
Saving Status during Interrupt Service
Before an interrupt request that has been arbitrated is actually serviced, the status of the
current task is automatically saved on the system stack. The CPU status (PSW) is saved
together with the location at which execution of the interrupted task is to be resumed after
returning from the service routine. This return location is specified through the Instruction
Pointer (IP) and, in the case of a segmented memory model, the Code Segment Pointer
(CSP). Bit SGTDIS in register SYSCON controls how the return location is stored.
The system stack receives the PSW first, followed by the IP (unsegmented), or followed
by CSP and then IP (segmented mode). This optimizes the usage of the system stack if
segmentation is disabled.
The CPU priority field (ILVL in PSW) is updated with the priority of the interrupt request
to be serviced, so the CPU now executes on the new level. If a multiplication or division
was in progress at the time the interrupt request was acknowledged, bit MULIP in
register PSW is set to ‘1’. In this case, the return location saved on the stack is not the
next instruction in the instruction flow, but rather the multiply or divide instruction itself,
as this instruction has been interrupted and will be completed after returning from the
service routine.
High
Addresses
Status of
Interrupted
Task
SP
---
SP
--
PSW
PSW
IP
CSP
--
IP
SP
Low
Addresses
a) System Stack before
Interrupt Entry
b) System Stack after
Interrupt Entry
(Unsegmented)
b) System Stack after
Interrupt Entry
(Segmented)
MCD02226
Figure 5-3
Task Status Saved on the System Stack
The interrupt request flag of the source being serviced is cleared. The IP is loaded with
the vector associated with the requesting source (CSP is cleared in the case of
segmentation), and the first instruction of the service routine is fetched from the vector
location which is expected to branch to the service routine itself. The data page pointers
and the context pointer are not affected.
When the interrupt service routine is exited (RETI is executed), the status information is
popped from the system stack in the reverse order, taking into account the value of bit
SGTDIS.
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Interrupt and Trap Functions
Context Switching
An interrupt service routine usually saves all the registers it uses on the stack and
restores them before returning. The more registers a routine uses, the more time is spent
saving and restoring. To save time, the C164CM allows switching the complete bank of
CPU registers (GPRs) with a single instruction, so the service routine executes within its
own separate context.
The instruction “SCXT CP, #New_Bank” pushes the content of the context pointer (CP)
on the system stack and loads CP with the immediate value “New_Bank”; this in turn,
selects a new register bank. The service routine may now use its “own registers”. This
register bank is preserved when the service routine terminates, i.e. its contents are
available on the next call.
Before returning (RETI) the previous CP is simply POPped from the system stack, which
returns the registers to the original bank.
Note: The first instruction following the SCXT instruction must not use a GPR.
Resources used by the interrupting program must eventually be saved and restored, e.g.
the DPPs and the registers of the MUL/DIV unit.
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Interrupt and Trap Functions
5.5
Interrupt Response Times
The interrupt response time defines the time from the setting of an interrupt request flag
of an enabled interrupt source to fetching of the first instruction (I1) from the interrupt
vector location. The basic interrupt response time for the C164CM is 3 instruction cycles.
Pipeline Stage
Cycle 1
Cycle 2
Cycle 3
Cycle 4
N
N+1
N+2
I1
DECODE
N-1
N
TRAP (1)
TRAP (2)
EXECUTE
N-2
N-1
N
TRAP
WRITEBACK
N-3
N-2
N-1
N
FETCH
Interrupt Response Time
1
IR-Flag
0
MCT04332
Figure 5-4
Pipeline Diagram for Interrupt Response Time
All instructions in the pipeline including instruction N (during which the interrupt request
flag is set) are completed before entering the service routine. Thus, the actual execution
time for these instructions (e.g. waitstates) influences the interrupt response time.
As shown in Figure 5-4 the respective interrupt request flag is set in cycle 1 (fetching of
instruction N). The indicated source wins the prioritization round (during cycle 2). In
cycle 3 a TRAP instruction is injected into the decode stage of the pipeline, replacing
instruction N+1 and clearing the source’s interrupt request flag to ‘0’. Cycle 4 completes
the injected TRAP instruction (save PSW, IP and CSP, if in segmented mode) and
fetches the first instruction (I1) from the respective vector location.
All instructions that entered the pipeline after setting of the interrupt request flag (N+1,
N+2) will be executed after returning from the interrupt service routine.
The minimum interrupt response time is 5 states (10 TCL). This requires program
execution from the internal code memory, no external operand read requests, and
setting the interrupt request flag during the last state of an instruction cycle. When the
interrupt request flag is set during the first state of an instruction cycle, the minimum
interrupt response time under these conditions is 6 state times (12 TCL).
The interrupt response time is increased by all delays of the instructions in the pipeline
that are executed before entering the service routine (including N).
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Interrupt and Trap Functions
• When internal hold conditions between instruction pairs N-2/N-1 or N-1/N occur, or
instruction N explicitly writes to the PSW or the SP, the minimum interrupt response
time may be extended by 1 state time for each of these conditions.
• When instruction N reads an operand from the internal code memory, or when N is a
call, return, trap, or MOV Rn, [Rm+ #data16] instruction, the minimum interrupt
response time may additionally be extended by 2 state times during internal code
memory program execution.
• In case instruction N reads the PSW and instruction N-1 has an effect on the condition
flags, the interrupt response time may additionally be extended by 2 state times.
The worst case interrupt response time during internal code memory program execution
adds to 12 state times (24 TCL).
Any reference to external locations increases the interrupt response time due to pipeline
related access priorities. The following conditions must be considered:
• Instruction fetch from an external location
• Operand read from an external location
• Result write-back to an external location
Depending on where the instructions, source and destination operands are located,
there are a number of combinations. Note, however, that only access conflicts contribute
to the delay.
A few examples illustrate these delays:
• The worst case interrupt response time including external accesses will occur when
instructions N, N+1 and N+2 are executed out of external memory, instructions N-1
and N require external operand read accesses, instructions N-3 through N write back
external operands, and the interrupt vector also points to an external location. In this
case, the interrupt response time is the time to perform 9 word bus accesses, because
instruction I1 cannot be fetched via the external bus until all write, fetch, and read
requests of preceding instructions in the pipeline are terminated.
• When the above example has the interrupt vector pointing into the internal code
memory, the interrupt response time is 7 word bus accesses plus 2 states, because
fetching of instruction I1 from internal code memory can start earlier.
• When instructions N, N+1 and N+2 are executed from external memory and the
interrupt vector also points to an external location, but all operands for instructions N-3
through N are in internal memory, the interrupt response time is the time needed to
perform 3 word bus accesses.
• When the above example has the interrupt vector pointing into the internal code
memory, the interrupt response time is 1 word bus access plus 4 states.
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Interrupt and Trap Functions
After an interrupt service routine has been terminated by executing the RETI instruction,
and if further interrupts are pending, the next interrupt service routine will not be entered
until at least two instruction cycles have been executed of the interrupted program. In
most cases, two instructions will be executed during this time. Typically, only one
instruction will be executed if the first instruction following the RETI instruction is a
branch instruction (without cache hit), or if it reads an operand from internal code
memory, or if it is executed from the internal RAM.
Note: A bus access in this context includes all delays which can occur during an external
bus cycle.
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Interrupt and Trap Functions
5.6
PEC Response Times
The PEC response time defines the time from the setting of an interrupt request flag of
an enabled interrupt source to the start of the PEC data transfer. The basic PEC
response time for the C164CM is 2 instruction cycles.
Pipeline Stage
Cycle 1
Cycle 2
Cycle 3
Cycle 4
N
N+1
N+2
N+2
DECODE
N-1
N
PEC
N+1
EXECUTE
N-2
N-1
N
PEC
WRITEBACK
N-3
N-2
N-1
N
FETCH
PEC Response Time
1
IR-Flag
0
MCT04333
Figure 5-5
Pipeline Diagram for PEC Response Time
In Figure 5-5 above the respective interrupt request flag is set in cycle 1 (fetching of
instruction N). The indicated source wins the prioritization round during cycle 2. In
cycle 3, a PEC transfer “instruction” is injected into the decode stage of the pipeline,
suspending instruction N+1 and clearing the source’s interrupt request flag to ‘0’. Cycle 4
completes the injected PEC transfer and resumes the execution of instruction N+1.
All instructions that entered the pipeline after setting of the interrupt request flag (N+1,
N+2) will be executed after the PEC data transfer.
Note: If instruction N reads any of the PEC control registers PECC7 … PECC0, when a
PEC request wins the current round of prioritization, this round is repeated and the
PEC data transfer is started one cycle later.
The minimum PEC response time is 3 states (6 TCL). This requires program execution
from the internal code memory, no external operand read requests, and setting the
interrupt request flag during the last state of an instruction cycle. When the interrupt
request flag is set during the first state of an instruction cycle, the minimum PEC
response time under these conditions is 4 state times (8 TCL).
The PEC response time is increased by all delays of the instructions in the pipeline that
are executed before starting the data transfer (including N).
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Interrupt and Trap Functions
• When internal hold conditions between instruction pairs N-2/N-1 or N-1/N occur, the
minimum PEC response time may be extended by 1 state time for each of these
conditions.
• When instruction N reads an operand from the internal code memory, or when N is a
call, return, trap, or MOV Rn, [Rm+ #data16] instruction, the minimum PEC response
time may additionally be extended by 2 state times during internal code memory
program execution.
• In the case that instruction N reads the PSW and instruction N-1 has an effect on the
condition flags, the PEC response time may additionally be extended by 2 state times.
The worst case PEC response time during internal code memory program execution
adds to 9 state times (18 TCL).
Any reference to external locations increases the PEC response time due to pipeline
related access priorities. The following conditions must be considered:
• Instruction fetch from an external location
• Operand read from an external location
• Result write-back to an external location
Depending on where the instructions, source and destination operands are located,
there are a number of combinations. Note, however, that only access conflicts contribute
to the delay.
A few examples illustrate these delays:
• The worst case interrupt response time including external accesses will occur when
instructions N and N+1 are executed out of external memory, instructions N-1 and N
require external operand read accesses, and instructions N-3, N-2 and N-1 write back
external operands. In this case, the PEC response time is the time to perform 7 word
bus accesses.
• When instructions N and N+1 are executed from external memory, but all operands
for instructions N-3 through N-1 are in internal memory, then the PEC response time
is the time to perform 1 word bus access plus 2 state times.
After a request for PEC service has been acknowledged by the CPU, the execution of
the next instruction is delayed by 2 state times plus the additional time it might take to
fetch the source operand from internal code memory or external memory and to write the
destination operand over the external bus in an external program environment.
Note: A bus access in this context includes all delays which can occur during an external
bus cycle.
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Interrupt and Trap Functions
5.7
Interrupt Node Sharing
Interrupt nodes may be shared among several module requests if either the requests are
generated mutually exclusively or the requests are generated at a low rate. If more than
one source is enabled in this case, the interrupt handler will first need to determine the
requesting source. However, this overhead is not critical for low rate requests.
This node sharing is controlled via the sub-node interrupt control register ISNC which
provides a separate request flag and enable bit for each supported request source. The
interrupt level used for arbitration is determined by the node control register (… IC).
The specific request flags within ISNC must be reset by software. If the respective
request is likely to be activated either at the time the request flag is cleared or shortly
thereafter, the request flag should be cleared together with the corresponding enable bit.
The enable bit can then be set again. This avoids undetected requests caused by pulses
at the interrupt node being too short.
ISNC
Interrupt Sub-Node Ctrl. Reg. ESFR (F1DEH/EFH)
Reset Value: 0000H
15
14
13
12
11
10
9
8
7
6
5
4
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Bit
Function
xxIR
Interrupt Request Flag for Source xx
0:
No request from source xx pending.
1:
Source xx has raised an interrupt request.
xxIE
Interrupt Enable Control Bit for Source xx
0:
Source xx interrupt request is disabled.
1:
Source xx interrupt request is enabled.
Table 5-7
Sub-node Control Bit Allocation
3
2
1
0
PLL PLL RTC RTC
IE
IR
IE
IR
rw
rwh
rw
rwh
Bit Position
Interrupt Source
Associated Node
15 … 4
Reserved.
Reserved.
3|2
PLL / OWD
XP3IC
1|0
RTC
XP3IC
Note: In order to ensure compatibility with other derivative devices application software
should never set reserved bits within register ISNC.
User’s Manual
5-24
V1.0, 2002-02
C164CM/C164SM
Derivatives
Interrupt and Trap Functions
5.8
External Interrupts
Although the C164CM has no dedicated INTR input pins, it supports many possibilities
to react to external asynchronous events. It does this by using a number of IO lines for
interrupt input. The interrupt function may be either combined with the pin’s main function
or used instead of it if the main pin function is not required.
Interrupt signals may be connected to:
•
•
•
•
EX3IN … EX0IN, the fast external interrupt input pins,
CC27IO … CC24IO, capture input / compare output lines of the CAPCOM2 unit,
CC19IO … CC16IO, capture input / compare output lines of the CAPCOM2 unit,
T4IN, T2IN, the timer input pins
For each of these pins, either a positive, a negative, or both a positive and a negative
external transition can be selected to cause an interrupt or PEC service request. The
edge selection is performed in the control register of the peripheral device associated
with the respective port pin. The peripheral must be programmed to a specific operating
mode to allow generation of an interrupt by the external signal. The priority of the
interrupt request is determined by the interrupt control register of the respective
peripheral interrupt source, and the interrupt vector of this source will be used to service
the external interrupt request.
Note: In order to use any of the listed pins as an external interrupt input, it must be
switched to input mode via its direction control bit DPx.y in the respective port
direction control register DPx.
Table 5-8
Pins Usable as External Interrupt Inputs
Port Pin
Original Function
Control Register
P1H.3-0/EX3-0IN
Fast external interrupt input pin
EXICON
P1H.7-4/CC27-24IO CAPCOM Register 27-24 Capture Input
CC27-CC24
P8.3-0/CC19-16IO
CAPCOM Register 19-16 Capture Input
CC19-CC16
P5.6/T2IN
Auxiliary timer T2 input pin
T2CON
P5.7/T4IN
Auxiliary timer T4 input pin
T4CON
User’s Manual
5-25
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C164CM/C164SM
Derivatives
Interrupt and Trap Functions
When port pins CCxIO are to be used as external interrupt input pins, bit field CCMODx
in the control register of the corresponding capture/compare register CCx must select
capture mode. When CCMODx is programmed to 001B, the interrupt request flag CCxIR
in register CCxIC will be set on a positive external transition at pin CCxIO. When
CCMODx is programmed to 010B, a negative external transition will set the interrupt
request flag. When CCMODx = 011B, both a positive and a negative transition will set
the request flag. In all three cases, the contents of the allocated CAPCOM timer will be
latched into capture register CCx, independent of whether or not the timer is running.
When the interrupt enable bit CCxIE is set, a PEC request or an interrupt request for
vector CCxINT will be generated.
Pins T2IN or T4IN can be used as external interrupt input pins when the associated
auxiliary timer T2 or T4 in block GPT1 is configured for capture mode. This mode is
selected by programming the mode control fields T2M or T4M in control registers
T2CON or T4CON to 101B. The active edge of the external input signal is determined by
bit fields T2I or T4I. When these fields are programmed to X01B, interrupt request flags
T2IR or T4IR in registers T2IC or T4IC will be set on a positive external transition at pins
T2IN or T4IN, respectively. When T2I or T4I is programmed to X10B, then a negative
external transition will set the corresponding request flag. When T2I or T4I is
programmed to X11B, both a positive and a negative transition will set the request flag.
In all three cases, the contents of the core timer T3 will be captured into the auxiliary
timer registers T2 or T4 based on the transition at pins T2IN or T4IN. When the interrupt
enable bits T2IE or T4IE are set, a PEC request or an interrupt request for vector T2INT
or T4INT will be generated.
Note: The non-maskable interrupt input pin NMI (sample rate 2 TCL) and the reset input
RSTIN provide another possibility for the CPU to react to an external input signal.
NMI and RSTIN are dedicated input pins which cause hardware traps.
User’s Manual
5-26
V1.0, 2002-02
C164CM/C164SM
Derivatives
Interrupt and Trap Functions
Fast External Interrupts
Input pins which may be used for external interrupts are sampled every 16 TCL; that is,
external events are scanned and detected in time frames of 16 TCL. The C164CM
provides 4 interrupt inputs that are sampled every 2 TCL, so external events are
captured faster than with standard interrupt inputs.
The lower 4 pins of Port P1H (P1H.3-P1H.0) can be programmed individually to this fast
interrupt mode, where the trigger transition (rising, falling or both) also can be selected.
The External Interrupt Control register EXICON controls this feature for all 4 pins.
EXICON
External Intr. Ctrl. Reg.
15
14
13
12
ESFR (F1C0H/E0H)
11
10
9
8
7
6
Reset Value: 0000H
5
4
3
2
1
0
-
-
-
-
EXI3ES
EXI2ES
EXI1ES
EXI0ES
-
-
-
-
rw
rw
rw
rw
Bit
Function
EXIxES
External Interrupt x Edge Selection Field (x = 7 … 0)
0 0: Fast external interrupts disabled: standard mode
0 1: Interrupt on positive edge (rising)
1 0: Interrupt on negative edge (falling)
1 1: Interrupt on any edge (rising or falling)
Note: The fast external interrupt inputs are sampled every 2 TCL. The interrupt request
arbitration and processing, however, is executed every 8 TCL.
The interrupt control registers listed below (CC11IC … CC8IC) control the fast external
interrupts of the C164CM. These fast external interrupt nodes and vectors are named
according to the C167’s CAPCOM channels CC11 … CC8, so interrupt nodes receive
identical names throughout the architecture. See register description below.
User’s Manual
5-27
V1.0, 2002-02
C164CM/C164SM
Derivatives
Interrupt and Trap Functions
CCxIC
CAPCOM x Intr. Ctrl. Reg.
15
14
13
12
11
SFR (See Table 5-9)
10
9
8
7
6
CCx CCx
IR
IE
-
-
-
-
-
-
-
-
rwh
rw
Reset Value: - - 00H
5
4
3
2
1
0
ILVL
GLVL
rw
rw
Note: Please refer to the general Interrupt Control Register description for an
explanation of the control fields.
Table 5-9
Fast External Interrupt Control Register Addresses
Register
Address
External Interrupt
CC8IC
FF88H / C4H
EX0IN
CC9IC
FF8AH / C5H
EX1IN
CC10IC
FF8CH / C6H
EX2IN
CC11IC
FF8EH / C7H
EX3IN
User’s Manual
5-28
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C164CM/C164SM
Derivatives
Interrupt and Trap Functions
External Interrupt Source Control
The input source for the fast external interrupts (controlled via register EXICON) can be
derived either from the associated port pin EXnIN or from an alternate source. This
selection is controlled via register EXISEL.
Activating the alternate input source, for example, allows the detection of transitions on
the interface lines of disabled interfaces. Upon this trigger, the respective interface can
be reactivated and respond to the detected activity.
EXISEL
Ext. Interrupt Source Reg.
15
14
13
12
11
ESFR(F1DAH/EDH)
10
9
8
7
6
Reset Value: 0000H
5
4
3
2
1
0
EXI7SS
EXI6SS
EXI5SS
EXI4SS
EXI3SS
EXI2SS
EXI1SS
EXI0SS
rw
rw
rw
rw
rw
rw
rw
rw
Bit
Function
EXIxSS
External Interrupt x Source Selection Field (x = 7 … 0)
00: Input from associated EXxIN pin.
01: Input from alternate pin.
10: Input from pin EXxIN ORed with alternate pin.
11: Input from pin EXxIN ANDed with alternate pin.
The Table 5-10 summarizes the association of the bitfields of register EXISEL with the
respective interface input lines.
Table 5-10
Connection of Interface Inputs to External Interrupt Nodes
Bitfield
Associated Interface Line
Notes
EXI0SS
CAN1_RxD
CAN (C164CM)
The used pin depends on the
assignment for the module.
EXI2SS
RxD0
ASC0
EXI3SS
SCLK
SSC
User’s Manual
5-29
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C164CM/C164SM
Derivatives
Interrupt and Trap Functions
External Interrupts During Sleep Mode
During Sleep Mode, all peripheral clock signals are deactivated. This also disables the
standard edge detection logic for the fast external interrupts. However, transitions on
these interrupt inputs must be recognized in order to initiate the wakeup. Therefore,
during Sleep Mode, special edge detection logic for the fast external interrupts (EXzIN)
is activated which requires no clock signal (therefore also works in Sleep mode) and is
equipped with an analog noise filter. This filter suppresses spikes (generated by noise)
up to 10 ns. Input pulses with a duration of 100 ns minimum are recognized and
generate an interrupt request.
This filter delays the recognition of an external wakeup signal by approximately 100 ns,
but the spike suppression ensures safe and robust operation of the sleep/wakeup
mechanism in an active environment.
100 ns
10 ns
Input
Signal
Interrupt
Request
Rejected
Recognized
MCD04456
Figure 5-6
User’s Manual
Input Noise Filter Operation
5-30
V1.0, 2002-02
C164CM/C164SM
Derivatives
Interrupt and Trap Functions
5.9
Trap Functions
Traps interrupt current execution in a manner similar to standard interrupts. However,
trap functions offer the possibility to bypass the interrupt system’s prioritization process
for cases in which immediate system reaction is required. Trap functions are not
maskable and always have priority over interrupt requests on any priority level.
The C164CM provides two different kinds of trapping mechanisms: Hardware Traps are
triggered by events that occur during program execution (such as illegal access or
undefined opcode); Software Traps are initiated via an instruction within the current
execution flow.
Software Traps
The TRAP instruction causes a software call to an interrupt service routine. The trap
number specified in the operand field of the trap instruction determines which vector
location in the address range from 00’0000H through 00’01FCH will be branched to.
Executing a TRAP instruction causes an effect similar to the occurrence of an interrupt
at the same vector. PSW, CSP (in segmentation mode), and IP are pushed on the
internal system stack and a jump is taken to the specified vector location. When
segmentation is enabled and a trap is executed, the CSP for the trap service routine is
set to code segment 0. No Interrupt Request flags are affected by the TRAP instruction.
The interrupt service routine called by a TRAP instruction must be terminated with a
RETI (return from interrupt) instruction to ensure correct operation.
Note: The CPU level in register PSW is not modified by the TRAP instruction, so the
service routine is executed on the same priority level from which it was invoked.
Therefore, the service routine entered by the TRAP instruction can be interrupted
by other traps or higher priority interrupts, other than when triggered by a
hardware trap.
Hardware Traps
Hardware traps are issued by faults or specific system states which occur during runtime
of a program (not identified at assembly time). A hardware trap may also be triggered
intentionally, for example: to emulate additional instructions by generating an Illegal
Opcode trap. The C164CM distinguishes eight different hardware trap functions. When
a hardware trap condition has been detected, the CPU branches to the trap vector
location for the respective trap condition. Depending on the trap condition, the instruction
which caused the trap is either completed or cancelled (i.e. it has no effect on the system
state) before the trap handling routine is entered.
Hardware traps are non-maskable and always have priority over every other CPU
activity. If several hardware trap conditions are detected within the same instruction
cycle, the highest priority trap is serviced (see Table 5-2).
User’s Manual
5-31
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C164CM/C164SM
Derivatives
Interrupt and Trap Functions
PSW, CSP (in segmentation mode), and IP are pushed on the internal system stack and
the CPU level in register PSW is set to the highest possible priority level (level 15),
disabling all interrupts. The CSP is set to code segment zero, if segmentation is enabled.
A trap service routine must be terminated with the RETI instruction.
The eight hardware trap functions of the C164CM are divided into two classes:
Class A traps are
• External Non-Maskable Interrupt (NMI)
• Stack Overflow
• Stack Underflow trap
These traps share the same trap priority, but have individual vector addresses.
Class B traps are
• Undefined Opcode
• Protection Fault
• Illegal Word Operand Access
• Illegal Instruction Access
• Illegal External Bus Access Trap
These traps share the same trap priority and the same vector address.
The bit-addressable Trap Flag Register (TFR) allows a trap service routine to identify the
kind of trap which caused the exception. Each trap function is indicated by a separate
request flag. When a hardware trap occurs, the corresponding request flag in register
TFR is set to ‘1’.
The reset functions (hardware, software, watchdog) may be regarded as a type of trap.
Reset functions have the highest system priority (trap priority III).
Class A traps have the second highest priority (trap priority II), on the 3rd rank are class
B traps, so a class A trap can interrupt a class B trap. If more than one class A trap occur
at a time, they are prioritized internally, with the NMI trap at the highest and the stack
underflow trap at the lowest priority.
All class B traps have the same trap priority (trap priority I). When several class B traps
become active at same time, the corresponding flags in the TFR register are set and the
trap service routine is entered. Because all class B traps have the same vector, the
priority of service for simultaneously occurring class B traps is determined by software
in the trap service routine.
A class A trap occurring during the execution of a class B trap service routine will be
serviced immediately. During the execution of a class A trap service routine, however,
any class B trap occurring will not be serviced until the class A trap service routine is
exited with a RETI instruction. In this case, the occurrence of the class B trap condition
is stored in the TFR register, but the IP value of the instruction which caused this trap is
lost.
User’s Manual
5-32
V1.0, 2002-02
C164CM/C164SM
Derivatives
Interrupt and Trap Functions
TFR
Trap Flag Register
15
14
13
STK
NMI STK
OF UF
rwh
rwh
rwh
SFR (FFACH/D6H)
Reset Value: 0000H
12
11
10
9
8
7
6
5
4
3
2
1
-
-
-
-
-
UND
OPC
-
-
-
PRT ILL ILL ILL
FLT OPA INA BUS
-
-
-
-
rwh
-
-
-
rwh
rwh
rwh
0
rwh
Bit
Function
ILLBUS
Illegal External Bus Access Flag
An external access has been attempted with no external bus defined.
ILLINA
Illegal Instruction Access Flag
A branch to an odd address has been attempted.
ILLOPA
Illegal Word Operand Access Flag
A word operand access (read or write) to an odd address has been
attempted.
PRTFLT
Protection Fault Flag
A protected instruction with an illegal format has been detected.
UNDOPC
Undefined Opcode Flag
The currently decoded instruction has no valid C164CM opcode.
STKUF
Stack Underflow Flag
The current stack pointer value exceeds the content of register STKUN.
STKOF
Stack Overflow Flag
The current stack pointer value falls below the content of reg. STKOV.
NMI
Non Maskable Interrupt Flag
A negative transition (falling edge) has been detected on pin NMI.
Note: The trap service routine must clear the respective trap flag; otherwise, a new trap
will be requested after exiting the service routine. Setting a trap request flag by
software causes the same effects as if it had been set by hardware.
In the case where e.g. an Undefined Opcode trap (class B) occurs simultaneously with
an NMI trap (class A), both the NMI and the UNDOPC flag is set, the IP of the instruction
with the undefined opcode is pushed onto the system stack, but the NMI trap is executed.
After return from the NMI service routine, the IP is popped from the stack and
immediately pushed again because of the pending UNDOPC trap.
User’s Manual
5-33
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C164CM/C164SM
Derivatives
Interrupt and Trap Functions
External NMI Trap
Whenever a high to low transition on the dedicated external NMI pin (Non-Maskable
Interrupt) is detected, the NMI flag in register TFR is set and the CPU will enter the NMI
trap routine. The IP value pushed on the system stack is the address of the instruction
following the one after which normal processing was interrupted by the NMI trap.
Note: The NMI pin is sampled with every CPU clock cycle to detect transitions.
Stack Overflow Trap
Whenever the stack pointer is decremented to a value which is less than the value in the
stack overflow register STKOV, the STKOF flag in register TFR is set and the CPU will
enter the stack overflow trap routine. Which IP value will be pushed onto the system
stack depends on which operation caused the decrement of the SP. When an implicit
decrement of the SP is made through a PUSH or CALL instruction, or upon interrupt or
trap entry, the IP value pushed is the address of the following instruction. When the SP
is decremented by a subtract instruction, the IP value pushed represents the address of
the instruction after the instruction following the subtract instruction.
For recovery from stack overflow, it must be ensured that there is enough excess space
on the stack to save the current system state twice (PSW, IP, in segmented mode also
CSP). Otherwise, a system reset should be generated.
Stack Underflow Trap
Whenever the stack pointer is incremented to a value greater than the value in the stack
underflow register STKUN, the STKUF flag is set in register TFR and the CPU will enter
the stack underflow trap routine. Again, which IP value will be pushed onto the system
stack depends on which operation caused the increment of the SP. When an implicit
increment of the SP is made through a POP or return instruction, the IP value pushed is
the address of the following instruction. When the SP is incremented by an add
instruction, the pushed IP value represents the address of the instruction after the
instruction following the add instruction.
Undefined Opcode Trap
When the instruction currently decoded by the CPU does not contain a valid C164CM
opcode, the UNDOPC flag is set in register TFR and the CPU enters the undefined
opcode trap routine. The IP value pushed onto the system stack is the address of the
instruction that caused the trap.
This can be used to emulate unimplemented instructions. The trap service routine can
examine the faulting instruction to decode operands for unimplemented opcodes based
on the stacked IP. In order to resume processing, the stacked IP value must be
incremented by the size of the undefined instruction, which is determined by the user,
before a RETI instruction is executed.
User’s Manual
5-34
V1.0, 2002-02
C164CM/C164SM
Derivatives
Interrupt and Trap Functions
Protection Fault Trap
Whenever one of the special protected instructions is executed where the opcode of that
instruction is not repeated twice in the second word of the instruction and the byte
following the opcode is not the complement of the opcode, the PRTFLT flag in register
TFR is set and the CPU enters the protection fault trap routine. The protected
instructions include DISWDT, EINIT, IDLE, PWRDN, SRST, and SRVWDT. The IP value
pushed onto the system stack for the protection fault trap is the address of the instruction
which caused the trap.
Illegal Word Operand Access Trap
Whenever a word operand read or write access is attempted to an odd byte address, the
ILLOPA flag in register TFR is set and the CPU enters the illegal word operand access
trap routine. The IP value pushed onto the system stack is the address of the instruction
following the one which caused the trap.
Illegal Instruction Access Trap
Whenever a branch is made to an odd byte address, the ILLINA flag in register TFR is
set and the CPU enters the illegal instruction access trap routine. The IP value pushed
onto the system stack is the illegal odd target address of the branch instruction.
Illegal External Bus Access Trap
Whenever the CPU requests an external instruction fetch, data read or data write, and
no external bus configuration has been specified, the ILLBUS flag in register TFR is set
and the CPU enters the illegal bus access trap routine. The IP value pushed onto the
system stack is the address of the instruction following the one which caused the trap.
User’s Manual
5-35
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C164CM/C164SM
Derivatives
Clock Generation
6
Clock Generation
All activities of the C164CM’s controller hardware and its on-chip peripherals are
controlled via the system clock signal fCPU.
This reference clock is generated in three stages, as shown in Figure 6-1:
• Oscillator
• Frequency Control
• Clock Drivers
Oscillator
The on-chip Pierce oscillator can run with an external crystal and appropriate oscillator
circuitry or it can be driven by an external oscillator or another clock source.
Frequency Control
The input clock signal feeds the controller hardware:
• Directly, providing phase coupled operation on input frequency which is not too high
• Divided by 2 to obtain 50% duty cycle clock signal
• Via an on-chip Phase Locked Loop (PLL) providing maximum performance on low
input frequency
• Via the Slow Down Divider (SDD) to reduce power consumption.
The resulting internal clock signal is referred to as “CPU clock” fCPU.
Clock Drivers
The CPU clock is distributed via separate clock drivers which feed the CPU and two
groups of peripheral modules. The Real Time Clock is fed with the prescaled oscillator
clock (fRTC) via a separate clock driver, so it is not affected by the clock control functions.
User’s Manual
6-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Clock Generation
Idle Mode
CCD
CPU
OSC
PCDDIS
PCD
Prescaler
PLL
SDD
Peripherals,
Ports, Intrl. Ctrl.
ICD
Interfaces
P. D. Mode
32:1
Oscillator
fRTC
Frequency Control
RTC
Clock Drivers
MCD04457
Figure 6-1
User’s Manual
CPU Clock Generation Stages
6-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
Clock Generation
6.1
Oscillator
The main oscillator of the C164CM is a power optimized Pierce oscillator providing an
inverter and a feedback element. Pins XTAL1 and XTAL2 connect the inverter to the
external crystal. The standard external oscillator circuitry (see Figure 6-2) comprises the
crystal, two low end capacitors, and a series resistor (Rx2) to limit the current through
the crystal. The additional LC combination is only required for 3rd overtone crystals to
suppress oscillation in the fundamental mode. A test resistor (RQ) may be temporarily
inserted to measure the oscillation allowance of the oscillator circuitry.
XTAL1
XTAL2
RQ
Rx2
MCS04335
Figure 6-2
External Oscillator Circuitry
The on-chip oscillator is optimized for an input frequency range of 4 to 16 MHz.
An external clock signal (e.g. from an external oscillator or from a master device) may
be fed to the input XTAL1. The Pierce oscillator then is not required to support the
oscillation itself, but is rather driven by the input signal. In this case, the input frequency
range may be 0 to 50 MHz (please note that the maximum applicable input frequency is
limited by the device’s maximum CPU frequency).
Note: Oscillator measurement within the final target system is recommended to
determine the actual oscillation allowance for the oscillator-crystal system. The
measurement technique, examples for evaluated systems, and recommendations
are provided in a specific application note about oscillators (available via your
representative or WWW).
User’s Manual
6-3
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C164CM/C164SM
Derivatives
Clock Generation
For input frequencies above 25 … 30 MHz the oscillator’s output should be terminated
as shown in Figure 6-3; at lower frequencies it may be left open. This termination
improves the operation of the oscillator by filtering out frequencies above the intended
oscillator frequency.
XTAL1
XTAL2
15 pF
Input Clock
3 kΩ
MCS04336
Figure 6-3
Oscillator Output Termination
Note: It is strongly recommended to measure the oscillation allowance (or margin) in the
final target system (layout) to determine the optimum parameters for the oscillator
operation.
User’s Manual
6-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
Clock Generation
6.2
Frequency Control
The CPU clock is based on either the Basic Clock or the Slow Down Clock. Both types
of clock are generated from the oscillator clock and are software selectable:
The Basic Clock is the standard operating clock for the C164CM and is required to
deliver the intended maximum performance. The clock configuration in register RP0H
(bitfield CLKCFG = RP0H.7-5) determines one of three possible basic clock generation
modes:
• Direct Drive: the oscillator clock is directly fed to the controller hardware.
• Prescaler: the oscillator clock is divided by 2 to achieve a 50% duty cycle.
• PLL: the oscillator clock is multiplied by a configurable factor of F = 1.5 … 5.
The Slow Down Clock is the oscillator clock divided by a programmable factor of
1 … 32 (additional 2:1 divider in prescaler mode). This alternate possibility runs the
C164CM at a lower frequency, determined by the programmed slow down factor, and
greatly reduces its power consumption.
Configuration
OWD
PLL
Oscillator
Clock
CPU Clock
fOSC
fCPU
SDD
2:1
Software
MCD04458
Figure 6-4
Frequency Control Paths
Note: The configuration register RP0H is loaded with the logic levels present on the
upper half of PORT0 (P0H) after a long hardware reset, i.e. bitfield CLKCFG
represents the logic levels on pins P0.15-13 (P0H.7-5).
User’s Manual
6-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
Clock Generation
The internal operation of the C164CM is controlled by the internal CPU clock fCPU. Both
edges of the CPU clock can trigger internal operations (example: pipeline) or external
operations (example: bus cycles) operations. See Figure 6-5.
Phase Locked Loop Operation
fOSC
tCL
tCL
tCL
tCL
fCPU
Direct Clock Drive
fOSC
fCPU
Prescaler Operation
fOSC
tCL
tCL
fCPU
SDD Operation
fOSC
tCL
tCL
fCPU
(CLKREL = 2, Direct Drive
tCL
tCL
(CLKREL = 2, Prescaler
fCPU
MCD04459
Figure 6-5
User’s Manual
Generation Mechanisms for the CPU Clock
6-6
V1.0, 2002-02
C164CM/C164SM
Derivatives
Clock Generation
Direct Drive
When direct drive is configured (CLKCFG = 011B), the C164CM’s clock system is
directly fed from the external clock input, i.e. fCPU = fOSC. This allows operation of the
C164CM with a reasonably small fundamental mode crystal. The specified minimum
values for the CPU clock phases (TCLs) must be respected. Therefore, the maximum
input clock frequency depends on the clock signal’s duty cycle.
Prescaler Operation
When prescaler operation is configured (CLKCFG = 001B), the C164CM’s input clock is
divided by 2 to generate the CPU clock signal, i.e. fCPU = fOSC/2. This requires the
oscillator (or input clock) to run on 2 times the intended operating frequency but
guarantees a 50% duty cycle for the internal clock system independent of the input clock
signal’s waveform.
PLL Operation
When PLL operation is configured (via CLKCFG), the C164CM’s input clock is fed to the
on-chip Phase Locked Loop circuit which multiplies its frequency by a factor of
F = 1.5 … 5 (selectable via CLKCFG, see Table 6-1) and generates a CPU clock signal
with 50% duty cycle, i.e. fCPU = fOSC × F.
The on-chip PLL circuit allows operation of the C164CM on a low frequency external
clock while still providing maximum performance. The PLL also provides fail safe
mechanisms which allow detection of frequency deviations and execution of emergency
actions in case of an external clock failure.
When the PLL detects a missing input clock signal, it generates an interrupt request. This
warning interrupt indicates that the PLL frequency is no longer locked, i.e. no longer
stable. This occurs when the input clock is unstable and especially when the input clock
fails completely, such as due to a broken crystal. In this case, the synchronization
mechanism will reduce the PLL output frequency down to the PLL’s base frequency
(2 … 5 MHz). The base frequency is still generated and allows the CPU to execute
emergency actions in case of a loss of the external clock.
On power-up, the PLL provides a stable clock signal within about 1 ms after VDD has
reached the specified valid range, even if there is no external clock signal (in this case
the PLL will run on its base frequency of 2 … 5 MHz). The PLL starts synchronizing with
the external clock signal as soon as it is available. Within about 1 ms after stable
oscillations of the external clock within the specified frequency range, the PLL will be
synchronous with this clock at a frequency of F × fOSC; meaning that the PLL locks to the
external clock.
When PLL operation is selected, the CPU clock is a selectable multiple of the oscillator
frequency, i.e. the input frequency.
Table 6-1 lists the possible selections.
User’s Manual
6-7
V1.0, 2002-02
C164CM/C164SM
Derivatives
Clock Generation
Table 6-1
C164CM Clock Generation Modes
RP0H.7-5
(P0H.7-5)
CPU Frequency External Clock
fCPU = fOSC × F Input Range1)
fOSC × 4
fOSC × 3
fOSC × 2
fOSC × 5
fOSC × 1
1 1 1
1 1 0
1 0 1
1 0 0
0 1 1
fOSC × 1.5
fOSC / 2
fOSC × 2.5
0 1 0
0 0 1
0 0 0
Notes
2.5 to 6.25 MHz
Default configuration
3.33 to 8.33 MHz
–
5 to 12.5 MHz
–
2 to 5 MHz
–
1 to 25 MHz
Direct drive2)
6.66 to 16.6 MHz
–
2 to 50 MHz
CPU clock via prescaler
4 to 10 MHz
–
1)
The external clock input range refers to a CPU clock range of 10 … 25 MHz.
2)
The maximum frequency depends on the duty cycle of the external clock signal. In emulation mode pin P0.15
(P0H.7) is inverted, i.e. the configuration ‘111’ would select direct drive in emulation mode.
The PLL constantly synchronizes to the external clock signal. Due to the fact that the
external frequency is 1/F’th of the PLL output frequency, the output frequency may be
slightly higher or lower than the desired frequency. This jitter is irrelevant for longer time
periods. For short periods (1 … 4 CPU clock cycles), it remains below 4%.
PLL Circuit
fIN
fPLL
fPLL = F × fIN
Reset
Reset
PWRDN
Sleep
fCPU
F
Lock
OWD
XP3INT
Figure 6-6
User’s Manual
CLKCFG
(RP0H.7-5)
MCB04339
PLL Block Diagram
6-8
V1.0, 2002-02
C164CM/C164SM
Derivatives
Clock Generation
6.3
Oscillator Watchdog
The C164CM provides an Oscillator Watchdog (OWD) which monitors the clock signal
fed to input XTAL1 of the on-chip oscillator (either with a crystal or via external clock
drive) in prescaler or direct drive mode (unless the PLL provides the basic clock). For
this operation, the PLL provides a clock signal (base frequency) which is used to
supervise transitions on the oscillator clock. This PLL clock is independent of the XTAL1
clock. When the expected oscillator clock transitions are missing, the OWD activates the
PLL Unlock / OWD interrupt node and supplies the CPU with the PLL clock signal instead
of the selected oscillator clock (see Figure 6-4). Under these circumstances, the PLL will
oscillate with its base frequency.
In direct drive mode the PLL base frequency is used directly (fCPU = 2 … 5 MHz).
In prescaler mode, the PLL base frequency is divided by 2 (fCPU = 1 … 2.5 MHz).
If the oscillator clock fails while the PLL provides the basic clock, the system will be
supplied with the PLL base frequency anyway.
Using this PLL clock signal, the CPU can either execute a controlled shutdown sequence
bringing the system into a defined and safe idle state, or it can provide an emergency
operation of the system with reduced performance based on this (normally slower)
emergency clock.
Note: The CPU clock source is switched back to the oscillator clock only after a
hardware reset.
The Oscillator Watchdog can be disabled by setting bit OWDDIS in register SYSCON.
In this case, the PLL remains idle and provides no clock signal, while the CPU clock
signal is derived directly from the oscillator clock or via prescaler or SDD. Also, no
interrupt request will be generated in case of a missing oscillator clock.
Note: At the end of an external reset, bit OWDDIS reflects the inverted level of pin RD
at that time. Thus, the Oscillator Watchdog may also be disabled via hardware by
(externally) pulling the RD line low upon a reset, in a manner similar to the
standard reset configuration via PORT0.
The oscillator watchdog cannot provide full security while the CPU clock signal is
generated by the SlowDown Divider because the OWD cannot switch to the PLL clock
in this case (see Figure 6-4). OWD interrupts are only recognizable if fOSC is still
available (for instance, the input frequency is too low or for intermittent failure only).
A broken crystal cannot be detected by software (OWD interrupt server) as no SDD clock
is available in such a case.
User’s Manual
6-9
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C164CM/C164SM
Derivatives
Clock Generation
6.4
Clock Drivers
The operating clock signal fCPU is distributed to the controller hardware via several clock
drivers which are disabled under certain circumstances. The Real Time Clock (RTC) is
clocked via a separate clock driver which delivers the prescaled oscillator clock (contrary
to the other clock drivers). Table 6-2 summarizes the different clock drivers and their
functions, especially in power reduction modes:
Table 6-2
Clock Drivers Description
Clock Driver Clock Active
Signal Mode
Idle
Mode
Connected Circuitry
Power
Down
and Sleep
Mode
CCD
CPU
Clock Driver
fCPU
ON
Off
Off
CPU,
internal memory modules
(IRAM, ROM/OTP/Flash)
ICD
Interface
Clock Driver
fCPU
ON
ON
Off
ASC0, WDT, SSC,
interrupt detection
circuitry
PCD
Peripheral
Clock Driver
fCPU
Control via Control via Off
PCDDIS
PCDDIS
RCD
RTC
Clock Driver
fRTC
ON
ON
(X)Peripherals (timers,
etc.) except those driven
by ICD,
interrupt controller, ports
Control via Real Time Clock
PDCON /
SLEEPCON
Note: Disabling PCD by setting bit PCDDIS stops the clock signal for all connected
modules. Ensure that all these modules are in a safe state before stopping their
clock signal.
The port input and output values will not change while PCD is disabled
(ASC0 and SSC will still operate, if active),
CLKOUT will be high if enabled.
Please also utilize the hints given in Section 21.5.
User’s Manual
6-10
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
7
Parallel Ports
In order to accept or generate single external control signals or parallel data, the
C164CM provides up to 50 parallel IO lines organized as follows: four 8-bit IO ports
(PORT0 made of P0H and P0L, PORT1 made of P1H and P1L), one 6-bit IO port
(Port 20), one 4-bit IO port (Port 8), and one 8-bit input port (Port 5).
These port lines may be used for general purpose Input/Output functions controlled via
software or may be used implicitly by the C164CM’s integrated peripherals or by the
External Bus Controller.
All port lines are bit addressable, and all input/output lines are individually (bit-wise)
programmable as inputs or outputs via direction registers (excluding Port 5, which is an
input only port). The IO ports are true bidirectional ports which are switched to high
impedance state when configured as inputs. The output drivers of Port 8 can be
configured (pin by pin) for push/pull operation or open-drain operation via a control
register.
The logic level of a pin is clocked into the input latch once per state time, regardless of
whether the port is configured for input or output.
A write operation to a port pin configured as an input causes the value to be written into
the port output latch, while a read operation returns the latched state of the pin itself. A
read-modify-write operation reads the value of the pin, modifies it, and writes it back to
the output latch.
Data Input/Output
Registers
Direction Control
Registers
P0L
DP0L
E
P0H
DP0H
E
P1L
DP1L
E
P1H
DP1H
E
Diverse Control
Registers
SYSCON
P5DIDIS
P5
P8
DP8
P20
DP20
E
ODP8
MCA05115
Figure 7-1
User’s Manual
SFRs and Pins Associated with the Parallel Ports
7-1
V1.0, 2002-02
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Derivatives
Parallel Ports
Writing to a pin configured as an output (DPx.y = ‘1’) causes the output latch and the pin
to have the written value, because the output buffer is enabled. Reading this pin returns
the value of the output latch. A read-modify-write operation reads the value of the output
latch, modifies it, and writes it back to the output latch, thus also modifying the level at
the pin.
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7-2
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Derivatives
Parallel Ports
7.1
Output Driver Control
The output driver of a port pin is activated by switching the respective pin to output, that
is, DPx.y = ‘1’. The value driven to the pin is determined by the port output latch or by
the associated alternate function (e.g. address, peripheral IO, etc.). The user software
can control the characteristics of the output driver via the following mechanisms:
• Open Drain Mode: The upper (push) transistor is always disabled. Only ‘0’ is driven
actively, an external pull-up is required.
• Driver Characteristic: The driver strength (delivered current) can be selected.
• Edge Characteristic: The shape of an output signal can be selected.
Open Drain Mode
In the C164CM, certain ports provide Open Drain Control, which allows switching the
output driver of a port pin from a push/pull configuration to an open drain configuration.
In push/pull mode, a port output driver has an upper and a lower transistor, thus, it can
actively drive the line to either a high or a low level. In open drain mode, the upper
transistor is always switched off, and the output driver can actively drive the line to a low
level only. When writing a ‘1’ to the port latch, the lower transistor is switched off and the
output enters a high-impedance state. The high level must then be provided by an
external pull-up device. With this feature, it is possible to connect several port pins
together to a Wired-AND configuration, saving external glue logic and/or additional
software overhead for enabling/disabling output signals.
This feature is controlled through the respective Open Drain Control Registers ODPx
provided for each port which has this feature implemented. These registers allow the
individual bit-wise selection of the open drain mode for each port line.
If the respective control bit ODPx.y is ‘0’ (default after reset), the output driver is in the
push/pull mode. If ODPx.y is ‘1’, the open drain configuration is selected. Note that all
ODPx registers are located in the ESFR space.
External
Pullup
Pin
Pin
Q
Q
Push/Pull Output Driver
Open Drain Output Driver
MCS01975
Figure 7-2
User’s Manual
Output Drivers in Push/Pull Mode and in Open Drain Mode
7-3
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C164CM/C164SM
Derivatives
Parallel Ports
Driver Characteristic
This defines the general driving capability of the respective driver. Reducing the driver
strength increases the output’s internal resistance which attenuates noise that is
imported/exported via the output line. For driving LEDs or power transistors, however, a
stable high output current may still be required.
The controllable output drivers of the C164CM pins feature differently sized transistors
for each direction (push and pull). The activation/deactivation of these transistors
determines the output characteristics of the respective port driver.
Three modes can be selected to adapt the driver characteristics to the application’s
requirements: Strong Driver Mode, Medium Driver Mode, and Weak Driver Mode.
In Strong Driver Mode, all transistors are activated. In this case, the driver provides
maximum output current supporting high current applications such as LEDs or
applications where fast signal transitions are required such as buses.
In Medium Driver Mode, not all transistors are activated. In this case, the driver
provides a reduced output current supporting applications with moderate requirements
for current or speed, while improving the EME behavior.
In Weak Driver Mode, only a small transistor is activated. In this case, the driver may
drive not time critical logic loads, while switching noise is greatly reduced.
Edge Characteristic
This defines the turn-on speed of the main driver stage, that is, the shape of the
respective output. Soft edges reduce the peak currents drawn when changing the
voltage level of an external capacitive load. For a bus interface, however, sharp edges
may still be required. Edge characteristic affects the pre-driver which controls the final
output driver stage.
Note: If Weak Driver Mode is selected additional edge shaping makes no sense and,
therefore, is not supported.
User’s Manual
7-4
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Derivatives
Parallel Ports
The Port Output Control registers POCONx provide the corresponding control bits.
For each group of four pins (that is, for each port nibble), a 4-bit control field is provided.
Word ports consume four control nibbles each, byte ports consume two control nibbles
each, where each control nibble controls 4 pins of the respective port.
The general register layout shown below is valid for all POCON registers. Please note
that for byte ports, only two bitfields are provided (see Table 7-1).
POCON*
Port * Output Ctrl. Reg.
15
14
13
12
11
ESFR (Table 7-1)
10
9
8
7
Reset Value: (Table 7-1)
6
5
4
3
2
1
PDM3N
PDM2N
PDM1N
PDM0N
rw
rw
rw
rw
Bit
Function
PDMxN
Port Driver Mode, Nibble x
Code Driver strength1)
0000: Strong driver,
0001: Strong driver,
0010: Strong driver,
0011: Weak driver3),
0100: Medium driver,
0101: Medium driver,
0110: Medium driver,
0111: Weak driver3),
1xxx: Reserved, do not use!
0
Edge shape2)
Sharp edge mode
Medium edge mode
Soft edge mode
no edge control
Sharp edge mode
Medium edge mode
Soft edge mode
no edge control
1)
Defines the current the respective driver can deliver to the external circuitry.
2)
Defines the switching characteristics to the respective new output level. This also influences the peak currents
through the driver when producing an edge, i.e. when changing the output level.
3)
This is the driver’s minimum strength. No additional edge shaping can be selected at this level.
Table 7-1 lists the defined POCON registers and the allocation of control bitfields and
port pins.
User’s Manual
7-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
Table 7-1
Port Output Control Register Allocation
Control
Register
Location
POCON20
Controlled Pins (by POCONx.y-z)
.15-12
.11-8
F0AAH / 55H
P20.12,
RSTOUT
P20.8,
P20.5-4,
CLKOUT/ ALE
FOUT
P20.1-0,
WR, RD
0000H
POCON8
F092H / 49H
---
---
---
P8.3-0
0022H
POCON1H
F086H / 43H
---
---
P1H.7-4
P1H.3-0
0011H
POCON1L
F084H / 42H
---
---
P1L.7-4
P1L.3-0
0011H
POCON0H
F082H / 41H
---
---
P0H.7-4
P0H.3-0
0011H
POCON0L
F080H / 40H
---
---
P0L.7-4
P0L.3-0
0011H
User’s Manual
7-6
.7-4
.3-0
Reset
Value
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
Port Driver Temperature Compensation
The temperature compensation for the port drivers provides driver output characteristics
which are stable (within a certain band of parameter variation) over the specified
temperature range, e.g. -40 °C … +125 °C. The drive capability of the output drivers is
reduced when the temperature is not in the upper range to improve the EME behavior.
The temperature compensation is based on a reference clock signal which is derived
from the CPU clock by a programmable divider (see Figure 7-3).
fCPU
fREF
N:1
Prog. Divider
N = (TCDIV+1)
Reference Clock
MCB05124
Figure 7-3
Temperature Compensation Clock Generation
The clock divider is programmed via bitfield TCDIV in register PTCR. TCDIV can be
calculated using the following formula:
TCDIV = Integer ((fCPU × 6.7) - 2) [fCPU in MHz]
Example for fCPU = 25 MHz:
TCDIV = Integer ((25 × 6.7) - 2) = 165 (= A5H).
Generally, temperature compensation is a transparent feature. The Port Temperature
Compensation Register PTCR provides access to the actual compensation value and
even allows software control of this mechanism.
This is useful in two cases:
• Device testing: the function of the compensation mechanism can be verified during
production testing or characterization.
• User control: during operation the device can be controlled via externally provided
compensation values rather than via the internal mechanism.
Temperature compensation is initialized using register PTCR (enable and prescaler
for reference clock).
The reference clock is used to generate a temperature-related count value which is
compared to three thresholds (temperature levels) at which the four control values (max,
high, low, min) are switched.
User’s Manual
7-7
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
PTCR
Port Temp. Comp. Reg.
15
14
13
12
11
ESFR (F0AEH/57H)
10
9
8
7
6
TCDIV
TCS
-
rw
rw
-
Reset Value: 0000H
5
4
3
2
1
0
TCC
TCE
-
TCV
rw
rw
-
rwh
Bit
Function
TCV
Temperature Compensation Value
The value which is currently generated by the temperature
compensation sensor. This value is fed to the port logic while bit TCS = ‘1’.
00: Maximum driver strength (no reduction),
i.e. very high temperature
…
…
11: Minimum driver strength (reduction for compensation),
i.e. very low temperature
Note: Bitfield TCV returns 00B when bit TCE = ‘0’ (always after reset).
TCE
Temperature Compensation Enable
0:
The temperature compensation sensor is deactivated (default).
The port drivers are not reduced (TCV = 00B).
1:
The temperature compensation is active.
TCC
Temperature Compensation Control
This value is fed to the port logic instead of the temperature
compensation sensor value, while bit TCS = ‘0’.
Encoding equal to TCV.
TCS
Temperature Compensation Source
0:
Port logic is controlled by software via bitfield TCC.
1:
Port logic is controlled by the temperature compensation sensor.
TCDIV
Temperature Compensation Clock Divider
This value adjusts the temperature compensation logic to the selected
operating frequency (see description).
User’s Manual
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Derivatives
Parallel Ports
7.2
Alternate Port Functions
To maximize flexibility for different applications and their specific IO requirements, port
lines have programmable alternate input or output functions associated with them.
Table 7-2
Port
Summary of Alternate Port Functions
Alternate Function(s)
Alternate Signal(s)
PORT0 Address and data lines when accessing
external resources (e.g. memory),
Input/output functions of serial interfaces
AD15 … AD0,
RxD0, TxD0,
MTSR, MRST, SCLK
PORT1 Capture inputs or compare outputs of the
CAPCOM units,
CC31IO … CC24IO,
CTRAP,
CC6n, COUT6n, CC6POSn,
EX3IN … EX0IN,
T7IN
Fast external interrupt inputs,
CAPCOM timer input
Port 5
Analog input channels to the A/D converter,
Timer control signal inputs
AN7 … AN0,
T2EUD, T3EUD, T4EUD,
T2IN, T3IN, T4IN
Port 8
Capture inputs or compare outputs of the
CAPCOM2 unit,
CAN interface (when assigned)
CC19IO … CC16IO,
Port 20 Bus control signals,
System clock or programmable frequency
output, reset output, configuration input
CAN1_TxD, CAN1_RxD
RD, WR, ALE,
CLKOUT/FOUT,
RSTOUT, EA
If an alternate output function of a pin is to be used, the alternate data must be routed
to the output driver and the driver must be enabled. For some alternate output signals,
such as bus signals or X-Peripheral signals, this is done automatically via separate
control lines, indicated by control line “AltEN” in the subsequent port figures. For the
remaining alternate output signals this has to be accomplished by user software. If the
alternate signal is combined with the port latch signal the respective port latch must be
set accordingly (see individual port figures). The output driver must be enabled by
switching the pin to output (DPx.y = ‘1’). Otherwise, the pin remains in the
high-impedance state and is not affected by the alternate output function.
If an alternate input function of a pin is used, the direction of the pin must be
programmed for input (DPx.y = ‘0’) if an external device is driving the pin. The input
direction is the default after reset. If no external device is connected to the pin, however,
one can also set the direction for this pin to output. In this case, the pin reflects the state
of the port output latch. Thus, the alternate input function reads the value stored in the
port output latch. This can be used for testing purposes to allow a software trigger of an
alternate input function by writing to the port output latch.
User’s Manual
7-9
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
On most of the port lines, the user software is responsible for setting the proper direction
when using an alternate input or output function of a pin. This is done by setting or
clearing the direction control bit DPx.y of the pin before enabling the alternate function.
There are port lines, however, for which the direction of the port line is switched
automatically. For instance, in the multiplexed external bus modes of PORT0, the
direction must be switched several times for an instruction fetch in order to output the
addresses and to input the data. Obviously, this cannot be done through instructions. In
these cases, the direction of the port line is switched automatically by hardware if the
alternate function of such a pin is enabled.
To determine the appropriate level of the port output latches, check how the alternate
data output is combined with the respective port latch output.
There is one basic structure for all port lines having only an alternate input function. Port
lines having only an alternate output function, however, have different structures due to
the way the direction of the pin is switched and depending on whether or not the pin is
accessible by the user software in the alternate function mode.
All port lines not used for these alternate functions may be used as general purpose IO
lines. When using port pins for general purpose output, the initial output value should be
written to the port latch prior to enabling the output drivers to avoid undesired transitions
on the output pins.
This applies to single pins as well as to pin groups (see examples below).
OUTPUT_ENABLE_SINGLE_PIN:
BSET
P8.0
;Initial output level is ‘high’
BSET
DP8.0
;Switch on the output driver
OUTPUT_ENABLE_PIN_GROUP:
BFLDL
P8, #05H, #05H
BFLDL
DP8, #05H, #05H
;Initial output level is ‘high’
;Switch on the output drivers
Note: When using several BSET pairs to control more pins of one port, these pairs must
be separated by instructions which do not reference the respective port (see
Section 4.2).
Each of these ports and the alternate input and output functions are described in detail
in the following subsections.
User’s Manual
7-10
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Derivatives
Parallel Ports
7.3
PORT0
The two 8-bit ports P0H and P0L represent the higher and lower parts of PORT0,
respectively. Both halves of PORT0 can be written (e.g. via a PEC transfer) without
affecting the other half.
If this port is used for general purpose IO, the direction of each line can be configured
via the corresponding direction registers DP0H and DP0L.
P0L
PORT0 Low Register
15
14
13
12
SFR (FF00H/80H)
11
10
9
8
7
6
Reset Value: - - 00H
5
4
3
2
1
0
P0L P0L P0L P0L P0L P0L P0L P0L
.7
.6
.5
.4
.3
.2
.1
.0
-
-
-
-
-
-
P0H
PORT0 High Register
15
14
13
12
-
-
rw
rw
rw
rw
SFR (FF02H/81H)
11
10
9
8
7
6
rw
rw
rw
rw
Reset Value: - - 00H
5
4
3
2
1
0
P0H P0H P0H P0H P0H P0H P0H P0H
.7
.6
.5
.4
.3
.2
.1
.0
-
-
-
-
-
-
-
-
rw
rw
Bit
Function
P0X.y
Port data register P0H or P0L bit y
User’s Manual
7-11
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Derivatives
Parallel Ports
DP0L
P0L Direction Ctrl. Register
15
14
13
12
11
ESFR (F100H/80H)
10
9
8
7
6
Reset Value: - - 00H
5
4
3
2
1
0
DP0L DP0L DP0L DP0L DP0L DP0L DP0L DP0L
.7
.6
.5
.4
.3
.2
.1
.0
-
-
-
-
-
-
DP0H
P0H Direction Ctrl. Register
15
14
13
12
11
10
-
-
rw
rw
rw
rw
ESFR (F102H/81H)
9
8
7
6
rw
rw
rw
rw
Reset Value: - - 00H
5
4
3
2
1
0
DP0H DP0H DP0H DP0H DP0H DP0H DP0H DP0H
.7
.6
.5
.4
.3
.2
.1
.0
-
-
-
-
-
-
-
-
rw
rw
rw
rw
rw
Bit
Function
DP0X.y
Port direction register DP0H or DP0L bit y
DP0X.y = 0: Port line P0X.y is an input (high-impedance)
DP0X.y = 1: Port line P0X.y is an output
rw
rw
rw
Alternate Functions of PORT0
When an external bus is enabled, PORT0 is used as data bus or address/data bus.
Note that an external 8-bit demultiplexed bus only uses P0L, while P0H is free for IO
(provided that no other bus mode is enabled).
PORT0 is also used to select the system startup configuration. During reset, PORT0 is
configured to input and each line is held high through an internal pull-up device. Each
line can now be individually pulled to a low level (see DC-level specifications in the
respective Data Sheets) through an external pull-down device. A default configuration is
selected when the respective PORT0 lines are at a high level. By pulling individual lines
to a low level, this default can be changed according to the needs of the applications.
The internal pull-up devices are designed such that external pull-down resistors (see
Data Sheet specification) can be used to apply a correct low level. These external
pull-down resistors can remain connected to the PORT0 pins also during normal
operation, however, care must be taken such that they do not disturb the normal function
of PORT0 (this might be the case, for example, if the external resistor is too strong).
On completion of reset, the selected bus configuration will be written to the BUSCON0
register. The configuration of the high byte of PORT0 will be copied into the special
register RP0H. This read-only register holds the selection for the number of chip selects
User’s Manual
7-12
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
and segment addresses. Software can read this register in order to react according to
the selected configuration, if required.
When the reset is terminated, the internal pull-up devices are switched off, and PORT0
will be switched to the appropriate operating mode.
During external accesses in multiplexed bus modes, PORT0 first outputs the 16-bit
intra-segment address as an alternate output function. PORT0 is then switched to
high-impedance input mode to read the incoming instruction or data. In 8-bit data bus
mode, two memory cycles are required for word accesses, the first for the low byte and
the second for the high byte of the word. During write cycles, PORT0 outputs the data
byte or word after outputting the address.
During external accesses in demultiplexed bus modes PORT0 reads the incoming
instruction or data word or outputs the data byte or word.
While external bus cycles are executed, PORT0 is controlled by the bus controller. The
port direction is determined by the type of the bus cycle, the data are transferred directly
from/to the bus controller hardware. The alternate output data can be the 16-bit
intrasegment address or the 8/16-bit data information. While PORT0 is not used by the
bus controller, it is controlled by its direction and output latch registers. User software
must therefore be very careful when writing to PORT0 registers while the external bus is
enabled. In most cases keeping the reset values will be the best choice.
The upper 5 pins of PORT0 additionally provide the interface lines for the serial
interfaces SSC (SCLK, MTSR, MRST) and ASC0 (RxD0, TxD0). The output lines are
ANDed with the respective port output latches (as it is in Port 3 of other controllers).
In 8-bit multiplexed address mode PORT0 only drives 11 address lines (A10 … AD0).
This reduces the external address space to 2 KBytes, but frees the interface pins for the
serial interfaces ASC0 and SSC. In this case the AltEN lines for the upper 5 pins are not
activated, i.e. the EBC does not control these pins.
Table 7-3
Alternate Functions of PORT0
PORT0 Pin(s) Alternate Function (8-Bit MUX)
P0H.7
P0H.6
P0H.5
P0H.4
P0H.3
P0H.2-0
P0L.7-0
User’s Manual
SCLK
MTSR
MRST
RxD0
TxD0
A10-8
AD7-0
SSC Shift Clock Input/Output
SSC Master Transmit / Slave Receive
SSC Master Receive / Slave Transmit
ASC0 Receive Data Input
ASC0 Transmit Data Output
Upper three Address Lines
Address/Data Lines
7-13
Altern. Function
(Others)
AD15
AD14
AD13
AD12
AD11
AD10-8
AD7-0
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
Alternate Function
P0H
Port 0
P0L
P0H.7
P0H.6
P0H.5
P0H.4
P0H.3
P0H.2
P0H.1
P0H.0
P0L.7
P0L.6
P0L.5
P0L.4
P0L.3
P0L.2
P0L.1
P0L.0
General Purpose
Input/Output
a)
c)
b)
SCLK
MTSR
MRST
RxD0
TxD0
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0
8-Bit
Demux Bus
16-Bit
Demux Bus
d)
SCLK
MTSR
MRST
RxD0
TxD0
A10
A9
A8
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
8-Bit
MUX Bus
AD15
AD14
AD13
AD12
AD11
AD10
AD9
AD8
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
16-Bit
MUX Bus
MCA05129
Figure 7-4
PORT0 IO and Alternate Functions
Figure 7-5 shows the structure of a PORT0 pin.
User’s Manual
7-14
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
Port Output
Latch
Read
Write
Read
Write
Internal Bus
Direction
Latch
1 0
0
1
AltDir
AltEN
Pin
0
1
AltDataOut
Driver
Clock
AltDataIN
Input
Latch
MCB04345
P0H.7-0, P0L.7-0
Figure 7-5
User’s Manual
Block Diagram of a PORT0 Pin
7-15
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
7.4
PORT1
The two 8-bit ports P1H and P1L represent the higher and lower part of PORT1,
respectively. Both halves of PORT1 can be written (e.g. via a PEC transfer) without
affecting the other half.
If this port is used for general purpose IO, the direction of each line can be configured
via the corresponding direction registers DP1H and DP1L.
P1L
PORT1 Low Register
15
14
13
12
SFR (FF04H/82H)
11
10
9
8
7
6
Reset Value: - - 00H
5
4
3
2
1
0
P1L P1L P1L P1L P1L P1L P1L P1L
.7
.6
.5
.4
.3
.2
.1
.0
-
-
-
-
-
-
P1H
PORT1 High Register
15
14
13
12
-
-
rw
rw
rw
rw
SFR (FF06H/83H)
11
10
9
8
7
6
rw
rw
rw
rw
Reset Value: - - 00H
5
4
3
2
1
0
P1H P1H P1H P1H P1H P1H P1H P1H
.7
.6
.5
.4
.3
.2
.1
.0
-
-
-
-
-
-
-
-
rwh
rwh
Bit
Function
P1X.y
Port data register P1H or P1L bit y
User’s Manual
7-16
rwh
rwh
rwh
rwh
rwh
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V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
DP1L
P1L Direction Ctrl. Register
15
14
13
12
11
ESFR (F104H/82H)
10
9
8
7
6
Reset Value: - - 00H
5
4
3
2
1
0
DP1 DP1 DP1 DP1 DP1 DP1 DP1 DP1
L.7 L.6 L.5 L.4 L.3 L.2 L.1 L.0
-
-
-
-
-
-
DP1H
P1H Direction Ctrl. Register
15
14
13
12
11
10
-
-
rw
rw
rw
rw
ESFR (F106H/83H)
9
8
7
6
rw
rw
rw
rw
Reset Value: - - 00H
5
4
3
2
1
0
DP1 DP1 DP1 DP1 DP1 DP1 DP1 DP1
H.7 H.6 H.5 H.4 H.3 H.2 H.1 H.0
-
-
-
-
-
-
-
-
rw
rw
rw
rw
rw
Bit
Function
DP1X.y
Port direction register DP1H or DP1L bit y
DP1X.y = 0: Port line P1X.y is an input (high-impedance)
DP1X.y = 1: Port line P1X.y is an output
rw
rw
rw
Alternate Functions of PORT1
When a demultiplexed external bus is enabled, PORT1 is used as address bus.
Note that demultiplexed bus modes use PORT1 as a 16-bit port. Otherwise, all 16 port
lines can be used for general purpose IO.
The lower 11 pins of PORT1 (P1H.2 … P1L.0) serve as the inputs/outputs for the
CAPCOM6 unit.
Pins P1H.3 … P1H.0 accept the fast external inputs. P1H.3 also serves as input for timer
T7.
The upper eight pins of PORT1 (P1H.7 … P1H.0) also serve as capture inputs or
compare outputs for the CAPCOM2 unit (CC27IO … CC24IO, CC31IO … CC28IO).
As all other capture inputs, the capture input function of pins P1H.7 … P1H.0 can also
be used as external interrupt inputs (sample rate 16 TCL).
As a side benefit, the capture input capability of these lines can also be used in the
address bus mode. In this way, changes to the upper address lines could be detected
and could trigger an interrupt request in order to perform some special service routines.
External capture signals can be applied only if no address output is selected for PORT1.
During external accesses in demultiplexed bus modes, PORT1 outputs the 16-bit
intra-segment address as an alternate output function.
User’s Manual
7-17
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
During external accesses in multiplexed bus modes, when no BUSCON register selects
a demultiplexed bus mode, PORT1 is not used and is available for general purpose IO.
When an external bus mode is enabled, the direction of the port pin and the loading of
data into the port output latch are controlled by the bus controller hardware. The input of
the port output latch is disconnected from the internal bus and is switched to the line
labeled “Alternate Data Output” via a multiplexer. The alternate data is the 16-bit
intrasegment address. While an external bus mode is enabled, the user software should
not write to the port output latch, otherwise, unpredictable results may occur. When the
external bus modes are disabled, the contents of the direction register last written by the
user become active.
Alternate Function
P1H
Port 1
P1L
P1H.7
P1H.6
P1H.5
P1H.4
P1H.3
P1H.2
P1H.1
P1H.0
P1L.7
P1L.6
P1L.5
P1L.4
P1L.3
P1L.2
P1L.1
P1L.0
General Purpose
Input/Output
a)
b)
A15
A14
A13
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
8/16-Bit
Demux Bus
c)
CC27IO
CC26IO
CC25IO
CC24IO
CC31IO
CC6POS2/CC30IO
CC6POS1/CC29IO
CC6POS0/CC28IO
CTRAP
COUT63
COUT62
CC62
COUT61
CC61
COUT60
CC60
CAPCOM
Inputs/Outputs
EX3IN, T7IN
EX2IN
EX1IN
EX0IN
Fast Ext. Interrupt
or Timer Input
MCA05128
Figure 7-6
PORT1 IO and Alternate Functions
The figures below show the structure of PORT1 pins. The upper 4 pins of PORT1
combine internal bus data and alternate data output before the port latch input.
User’s Manual
7-18
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
0 1
Port Output
Latch
Read
CCx
Write
Write
Read
Internal Bus
Direction
Latch
1 0
0
1
AltDir
AltEN
0
1
AltDataOut
Driver
AltDataIN (Latch)
Pin
Clock
AltDataIN (Pin)
Input
Latch
MCD04467
P1H.7-0, x = 27-24, 31-28
Figure 7-7
User’s Manual
Block Diagram of a PORT1 Pin with Address and CAPCOM Function
7-19
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
Port Output
Latch
Read
Write
Read
Write
Internal Bus
Direction
Latch
1 0
0
1
AltDir = '1'
AltEN
Pin
0
1
AltDataOut
Driver
Clock
Input
Latch
MCB04348
P1H.3-0, P1L.7-0
Figure 7-8
User’s Manual
Block Diagram of a PORT1 Pin with Address and
Alternate Input/Output Function
7-20
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
7.5
Port 5
This 8-bit input port can only read data. There is no output latch or direction register.
Data written to P5 will be lost.
P5
Port 5 Data Register
SFR (FFA2H/D1H)
15
14
13
12
11
10
9
8
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
7
6
Reset Value: XXXXH
5
4
3
2
1
0
P5.7 P5.6 P5.5 P5.4 P5.3 P5.2 P5.1 P5.0
r
r
Bit
Function
P5.y
Port data register P5 bit y (Read only)
r
r
r
r
r
r
Alternate Functions of Port 5
Each line of Port 5 is also connected to the input multiplexer of the Analog/Digital
Converter. All port lines can accept analog signals (ANx) which can be converted by the
ADC. For pins to be used as analog inputs it is recommended to disable the digital input
stage via register P5DIDIS (see description below). This avoids undesired cross currents
and switching noise while the (analog) input signal level is between VIL and VIH. Some
pins of Port 5 also serve as external GPT timer control lines.
Table 7-4 summarizes the alternate functions of Port 5.
Table 7-4
Alternate Functions of Port 5
Port 5 Pin Alternate Function a)
Alternate Function b)
P5.0
P5.1
P5.2
P5.3
P5.4
P5.5
P5.6
P5.7
–
–
T3EUD
T3IN
T2EUD
T4EUD
T2IN
T4IN
Analog Input AN0
Analog Input AN1
Analog Input AN2
Analog Input AN3
Analog Input AN4
Analog Input AN5
Analog Input AN6
Analog Input AN7
User’s Manual
7-21
Timer 3 ext. Up/Down Input
Timer 3 Count Input
Timer 2 ext. Up/Down Input
Timer 4 ext. Up/Down Input
Timer 2 Count Input
Timer 4 Count Input
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
Alternate Function
Port 5
a)
P5.7
P5.6
P5.5
P5.4
P5.3
P5.2
P5.1
P5.0
General Purpose
Input
b)
AN7
AN6
AN5
AN4
AN3
AN2
AN1
AN0
A/D Converter
Input
T4IN
T2IN
T4EUD
T2EUD
T3IN
T3EUD
Timer Control
Input
MCA05136
Figure 7-9
Port 5 IO and Alternate Functions
Port 5 Digital Input Control
Port 5 pins may be used for either digital or analog input. By setting the respective bit in
register P5DIDIS, the digital input stage of the respective Port 5 pin can be disconnected
from the pin. This is recommended when the pin is to be used as analog input as it
reduces the current through the digital input stage and prevents it from toggling while the
(analog) input level is between the digital low and high thresholds. Thus, the consumed
power and the generated noise can be reduced.
After reset all digital input stages are enabled.
User’s Manual
7-22
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
P5DIDIS
P5 Dig. Inp. Disable Reg.
SFR (FFA4H/D2H)
15
14
13
12
11
10
9
8
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
7
6
Reset Value: 0000H
5
4
3
2
1
0
P5D P5D P5D P5D P5D P5D P5D P5D
.7
.6
.5
.4
.3
.2
.1
.0
rw
rw
rw
rw
rw
rw
rw
rw
Bit
Function
P5D.y
Port P5 Bit y Digital Input Control
0:
Digital input stage connected to port line P5.y
1:
Digital input stage disconnected from port line P5.y
When being read or used as alternate input this line appears as ‘1’.
Port 5 pins have a special port structure (see Figure 7-10) for two reasons: First,
because it is an input only port; second, because the analog input channels are
connected directly to the pins rather than to the input latches.
Read
Internal Bus
DigInputEN
Clock
AltDataIn
Input
Latch
ChannelSelect
Pin
AnalogInput
MCB04357
P5.7-0
Figure 7-10 Block Diagram of a Port 5 Pin
Note: The “AltDataIn” line does not exist on all Port 5 inputs.
User’s Manual
7-23
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
7.6
Port 8
If this 4-bit port is used for general purpose IO, the direction of each line can be
configured via the corresponding direction register DP8. Each port line can be switched
into push/pull or open drain mode via the open drain control register ODP8.
P8
Port 8 Data Register
15
-
14
13
-
-
12
-
SFR (FFD4H/EAH)
11
-
10
-
9
-
8
-
Bit
Function
P8.y
Port data register P8 bit y
DP8
P8 Direction Ctrl. Register
15
-
14
13
-
-
12
-
11
-
Reset Value: - - 00H
7
6
5
4
-
-
-
-
P8.3 P8.2 P8.1 P8.0
-
-
-
-
rwh
SFR (FFD6H/EBH)
10
-
9
-
8
-
3
7
6
5
4
-
-
-
-
-
-
-
-
3
rwh
rwh
0
rwh
2
1
0
DP8 DP8 DP8 DP8
.3
.2
.1
.0
rw
Function
DP8.y
Port direction register DP8 bit y
DP8.y = 0: Port line P8.y is an input (high-impedance)
DP8.y = 1: Port line P8.y is an output
7-24
1
Reset Value: - - 00H
Bit
User’s Manual
2
rw
rw
rw
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
ODP8
P8 Open Drain Ctrl. Reg.
15
-
14
13
-
-
12
-
11
-
ESFR (F1D6H/EBH)
10
-
9
-
8
-
Reset Value: - - 00H
7
6
5
4
-
-
-
-
-
-
-
-
3
2
1
0
ODP8 ODP8 ODP8 ODP8
.3
.2
.1
.0
rw
rw
Bit
Function
ODP8.y
Port 8 Open Drain control register bit y
ODP8.y = 0: Port line P8.y output driver in push/pull mode
ODP8.y = 1: Port line P8.y output driver in open drain mode
rw
rw
Alternate Functions of Port 8
All Port 8 lines serve as capture inputs or compare outputs (CCxIO) for the CAPCOM2
unit (see Table 7-5).
When a Port 8 line is used as a capture input, the state of the input latch, representing
the state of the port pin, is directed to the CAPCOM unit via the line “Alternate Pin Data
Input”. If an external capture trigger signal is used, the direction of the respective pin
must be set to input. If the direction is set to output, the state of the port output latch will
be read, because the pin represents the state of the output latch. This can be used to
trigger a capture event through software by setting or clearing the port latch. Note that
in the output configuration, no external device may drive the pin, otherwise conflicts
would occur.
When a Port 8 line is used as a compare output (compare modes 1 and 3), the compare
event (or the timer overflow in compare mode 3) directly affects the port output latch. In
compare mode 1, when a valid compare match occurs, the state of the port output latch
is read by the CAPCOM control hardware via the line “Alternate Latch Data Input”, is
inverted, and then written back to the latch via the line “Alternate Data Output”. The port
output latch is clocked by the signal “Compare Trigger” which is generated by the
CAPCOM unit. In compare mode 3, when a match occurs, the value ‘1’ is written to the
port output latch via the line “Alternate Data Output”. When an overflow of the
corresponding timer occurs, a ‘0’ is written to the port output latch. In both cases, the
output latch is clocked by the signal “Compare Trigger”. The direction of the pin should
be set to output by the user; otherwise, the pin will be in the high-impedance state and
will not reflect the state of the output latch.
As can be seen from the port structure below, the user software always has free access
to the port pin even when it is used as a compare output. This is useful for setting up the
initial level of the pin when using compare mode 1 or the double-register mode. In these
modes, unlike in compare mode 3, the pin is not set to a specific value when a compare
match occurs, but is toggled instead.
User’s Manual
7-25
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
If the user wants to write to the port pin at the same time that a compare trigger tries to
clock the output latch, the write operation of the user software has priority. Each time a
CPU write access to the port output latch occurs, the input multiplexer of the port output
latch is switched to the line connected to the internal bus. The port output latch will
receive the value from the internal bus and the hardware triggered change will be lost.
As with all other capture inputs, the capture input function of the Port 8 pins can also be
used as external interrupt input (sample rate 16 TCL).
The CAN interface can use 2 pins of Port 8 to interface the CAN Module to an external
transceiver. In this case, the number of possible CAPCOM IO lines is reduced.
Table 7-5
Alternate Functions of Port 8
Port 8 Pin
Alternate Function
P8.0
P8.1
P8.2
P8.3
CC16IO
CC17IO
CC18IO
CC19IO
Alternate Function
Port 8
P8.3
P8.2
P8.1
P8.0
General Purpose
Input/Output
Capture input / compare output channel 16 or CAN
Capture input / compare output channel 17 or CAN
Capture input / compare output channel 18 or CAN
Capture input / compare output channel 19 or CAN
a)
b)
CC19IO
CC18IO
CC17IO
CC16IO
CAPCOM2
Capt.Inp./Comp.Outp.
-
CAN1_TxD
CAN1_RxD
CAN1_TxD
CAN1_RxD
CAN Interface
MCA05084
Figure 7-11 Port 8 IO and Alternate Functions
Note: The usage of Port 8 pins for CAN interface lines depends on the chosen
assignment for the CAN module.
CAN interface lines will override general purpose IO and CAPCOM IO lines.
User’s Manual
7-26
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
The pins of Port 8 combine internal bus data and alternate data output before the port
latch input.
0 1
Port Output
Latch
Direction
Latch
Read
Write
Read
CCx
Write
Write
Read
Internal Bus
Open Drain
Latch
1 0
0
1
AltDir
AltEN
Pin
0
1
AltDataOut
Driver
AltDataIn (Latch)
Clock
AltDataIN (Pin)
Input
Latch
MCB04430
P8.3-0
Figure 7-12 Block Diagram of Port 8 Pins with an Alternate CAPCOM IO and
CAN Interface Function
User’s Manual
7-27
V1.0, 2002-02
C164CM/C164SM
Derivatives
Parallel Ports
7.7
Port 20
If this 6-bit port is used for general purpose IO, the direction of each line can be
configured via the corresponding direction register DP20.
P20
Port 20 Data Register
SFR (FFB4H/DAH)
15
14
13
12
11
10
9
8
7
6
-
-
-
P20
.12
-
-
-
P20
.8
-
-
-
-
-
rw
-
-
-
rw
-
-
Bit
Function
P20.y
Port data register P20 bit y
DP20
P20 Direction Ctrl. Register
1)
Reset Value: 0000H
5
4
P20 P20
.5
.4
rw
rw
SFR (FFB6H/DBH)
15
14
13
12
11
10
9
8
7
6
-
-
-
DP20
.12
-
-
-
DP20
.8
-
-
-
-
-
rw
-
-
-
rw
-
-
3
2
1
0
-
-
P20
.1
P20
.0
-
-
rw
rw
Reset Value: 1000H
5
4
DP20
DP20
.51)
.4
rw
rw
3
2
-
-
-
-
1
0
DP20 DP20
.1
.0
rw
rw
ROM-version only! No output driver for this pin in OTP devices.
Bit
Function
DP20.y
Port direction register DP20 bit y
0:
Port line P20.y is an input (high-impedance)
1:
Port line P20.y is an output
Note: After reset the output driver of pin P20.12 is enabled, i.e. DP20.12 = ‘1’.
Note: The output driver of pin P20.5/EA is implemented only in the ROM-version.
In the OTP-version pin P20.5/EA must accept the 12 V programming voltage
and therefore cannot provide an output driver.
User’s Manual
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Derivatives
Parallel Ports
Alternate Functions of Port 20
The pins of Port 20 serve for various functions which include bus interface command
lines and several system control lines.
Table 7-6 summarizes the alternate functions of Port 20.
Table 7-6
Alternate Functions of Port 20
Port 20 Pin
Alternate Function
P20.0
P20.1
–
–
P20.4
P20.5
–
–
P20.8
RD
WR
–
–
ALE
EA
–
–
CLKOUT/
FOUT
–
–
–
RSTOUT
–
–
–
–
–
–
P20.12
–
–
–
Read command signal
Write command signal
Address latch enable signal
External access control input
System Clock Output/
Programmable Frequency Output
Reset indication output
Port 20 provides a set of general system control signals (in particular in case of an
external bus interface). To ensure proper operation of these signals most of the Port 20
alternate functions are enabled after reset (contrary to the other ports).
The general purpose IO functions are selected by the Port 20 enable bit P20EN
(SYSCON.5). The reset value of bit P20EN depends on the reset configuration:
After an external reset (EA = ‘0’) P20EN is always cleared, that means the IO functions
are always disabled.
After an internal reset (EA = ‘1’) P20EN is initialized with the inverted value latched from
pin WR. This means, the IO functions of Port 20 can be enabled by pulling pin WR low
at the end of reset.
Note: The operating mode of Port 20 can be selected by software (via bit P20EN) any
time before the execution of EINIT.
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Derivatives
Parallel Ports
Alternate Function
Port 20
b)
a)
RSTOUT
CLKOUT/FOUT
ALE
WR
RD
P20.12
P20.8
P20.5
P20.4
P20.1
P20.0
General Purpose
Input/Output
During
Operation
EA
B/St Mode
P20 OFF/ON
Boot/Start
Reset
Configuration
MCA05116
Figure 7-13 Port 20 IO and Alternate Functions
The port structure of the Port 20 pins depends on their alternate function (see
Figure 7-14).
Note: Enabling the CLKOUT function automatically enables the P20.8 output driver.
Setting bit DP20.8 = ‘1’ is not required.
The CLKOUT function is automatically enabled in emulation mode.
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Derivatives
Parallel Ports
Port Output
Latch
Read
Write
Read
Write
Internal Bus
Direction
Latch
1 0
0
1
AltDir
AltEN
Pin
0
1
AltDataOut
Driver
Clock
Input
Latch
AltDataIn
MCB05117
P20.12, P20.5, P20.4, P20.1, P20.0
Figure 7-14 Block Diagram of a Port 20 Pin with Alternate Input or Alternate
Output Function
Note: Signal AltEN in the above figure equals the inverted Port 20 enable signal
(P20EN).
Not all pins of Port 20 have both alternate output functions and alternate input
functions.
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Derivatives
Parallel Ports
Port Output
Latch
Read
Write
Read
Write
Internal Bus
Direction
Latch
1 0
FOEN
FOUT
>1
0
1
CLKEN
Pin
0
1
CLKOUT
Driver
Clock
Input
Latch
MCB05118
P20.8
Figure 7-15 Pin Control for Pin P20/CLKOUT/FOUT
Note: Enabling the CLKOUT function automatically enables the P20.8 output driver.
Setting bit DP20.8 = ‘1’ is not required.
For FOUT the pin driver must be enabled by setting bit DP20.8.
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Derivatives
Dedicated Pins
8
Dedicated Pins
Most of the input/output or control signals of the C164CM are implemented as alternate
functions of the parallel ports pins. There are, however, a number of signals which use
separate pins, including the oscillator, special control signals, and the power supply.
Table 8-1 summarizes the 14 dedicated pins of the C164CM.
Table 8-1
C164CM Dedicated Pins
Pin(s)
Function
NMI
Non-Maskable Interrupt Input
XTAL1, XTAL2
Oscillator Input/Output
RSTIN
Reset Input
VAREF, VAGND
VDD
VSS
Voltage Reference for Analog/Digital Converter
Digital Power Supply (4 pins)
Digital Reference Ground (4 pins)
The Non-Maskable Interrupt Input NMI allows triggering of a high priority trap via an
external signal (e.g. a power-fail signal). It also serves to validate the PWRDN instruction
which switches the C164CM into Power-Down mode. The NMI pin is sampled with every
CPU clock cycle to detect transitions.
The Oscillator Input XTAL1 and Output XTAL2 connect the internal Main Oscillator
to the external crystal. The oscillator provides an inverter and a feedback element. The
standard external oscillator circuitry (see Chapter 6) consists of the crystal, two low end
capacitors, and a series resistor to limit the current through the crystal. The main
oscillator is intended for the generation of the basic operating clock signal of the
C164CM.
An external clock signal may be fed to the input XTAL1, leaving XTAL2 open or
terminating it for higher input frequencies.
The Reset Input RSTIN allows the C164CM to be put into the well-defined reset
condition either at power-up or on external events such as a hardware failure or manual
reset. The input voltage threshold of the RSTIN pin is raised compared to the standard
pins to minimize the noise sensitivity of the reset input.
In bidirectional reset mode, the C164CM’s line RSTIN may be driven active by the chip
logic in order to support external equipment which is required for startup (e.g. flash
memory).
Bidirectional reset reflects internal reset sources (software, watchdog) to the RSTIN pin
and converts short hardware reset pulses to a minimum duration of the internal reset
sequence. Bidirectional reset is enabled by setting bit BDRSTEN in register SYSCON
and changes RSTIN from a pure input to an open drain IO line. When an internal reset
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C164CM/C164SM
Derivatives
Dedicated Pins
is triggered by the SRST instruction, or by a watchdog timer overflow, or by application
of a low level to the RSTIN line, an internal driver pulls it low for the duration of the
internal reset sequence. It is released afterwards and is then controlled by the external
circuitry alone.
The bidirectional reset function is useful for applications in which external devices
require a defined reset signal but cannot be connected to the C164CM’s RSTOUT
signal, e.g. an external flash memory which must come out of reset and deliver code well
before RSTOUT can be deactivated via EINIT.
The following behavior differences must be observed when using the bidirectional reset
feature in an application:
• Bit BDRSTEN in register SYSCON cannot be changed after EINIT and is cleared
automatically after a reset.
• The reset indication flags always indicate a long hardware reset.
• The PORT0 configuration is treated like on a hardware reset. In particular, the
bootstrap loader may be activated when P0L.4 is low.
• Pin RSTIN may be connected only to external reset devices with an open drain output
driver.
• A short hardware reset is extended to the duration of the internal reset sequence.
The Reference Voltage pins for the Analog/Digital Converter VAREF and VAGND
provide a separate power supply (reference voltage) for the comparator circuitry of the
on-chip ADC. This reduces the noise which is coupled to the analog input signals from
the digital logic sections and so improves the stability of the conversion results when
VAREF and VAGND are properly discoupled from VDD and VSS.
The Power Supply pins VDD and VSS provide the power supply for the digital logic of
the C164CM. The respective VDD/VSS pairs should be decoupled as close to the pins as
possible. For best results, it is recommended to implement two-level decoupling, for
example, the widely used 100 nF in parallel with 30 … 40 pF capacitors which deliver
the peak currents.
Note: All VDD pins and all VSS pins must be connected to the power supply and ground,
respectively.
The External Programming Voltage VPP is applied to pin P20.5/EA/VPP. This is
required to program the on-chip OTP program memory.
Note: This feature is only available in OTP-devices, of course.
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Derivatives
External Bus Interface
9
External Bus Interface
Although the C164CM provides a powerful set of on-chip peripherals and on-chip RAM
and ROM/OTP/Flash (except for ROMless versions) areas, these internal units cover
only a small fraction of its address space of up to 16 MBytes. The External Bus Interface
allows access to external peripherals and additional volatile and non-volatile memory.
The External Bus Interface supports a variety of configurations so it can be tailored to fit
perfectly into a given application system.
Ports & Direction Control
Alternate Functions
Address Registers
Mode Registers
P0L / P0H
P1L / P1H
BUSCON0
SYSCON
ADDRSEL1
BUSCON1
RP0H
ADDRSEL2
BUSCON2
ADDRSEL3
BUSCON3
ADDRSEL4
BUSCON4
PORT0
PORT1
RD
WR
P0L/P0H
P1L/P1H
ADDRSELx
Control Registers
PORT0 Data Register
PORT1 Data Register
Address Range Select
Register 1...4
EA
RSTIN
ALE
BUSCONx
SYSCON
RP0H
Bus Mode Control Register 0...4
System Control Register
Port P0H Reset Configuration Register
MCA05127
Figure 9-1
SFRs and Port Pins Associated with the External Bus Interface
Accesses to external memory or peripherals are executed by the integrated External Bus
Controller (EBC). The function of the EBC is controlled via the SYSCON register and the
BUSCONx and ADDRSELx registers. The BUSCONx registers specify the external bus
cycles in terms of address (mux/demux), data width (16-bit/8-bit), chip selects, and
length (waitstates / ALE / RW delay). These parameters are used for accesses within a
specific address area as defined via the corresponding register ADDRSELx.
The four pairs BUSCON1/ADDRSEL1 … BUSCON4/ADDRSEL4 allow definition of four
independent “address windows”, while all external accesses outside these windows are
controlled via register BUSCON0.
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Derivatives
External Bus Interface
9.1
Single Chip Mode
Single Chip Mode is entered when pin EA is high during reset. In this case, register
BUSCON0 is initialized with 00C0H; this also resets bit BUSACT0, so no external bus is
enabled.
In Single Chip Mode, the C164CM operates using only internal resources. No external
bus is configured and no external peripherals and/or memory can be accessed. Also no
port lines are occupied for the bus interface. When running in Single Chip Mode,
however, external access may be enabled by configuring an external bus under software
control. Single Chip Mode allows the C164CM to start execution from the internal
program memory (Mask-ROM, OTP or Flash memory).
Note: Any attempt to access a location in the external memory space in Single Chip
Mode results in the hardware trap ILLBUS if no external bus has been explicitly
enabled by software.
9.2
External Bus Modes
When the external bus interface is enabled (bit BUSACTx = ‘1’) and configured (bitfield
BTYP), the C164CM uses a subset of its port lines to build the external bus.
Table 9-1
Summary of External Bus Modes
BTYP
Encoding
External Data
Bus Width
External Address
Bus Width
External Address
Bus Mode
00
8-bit Data
16-bit: A15 … A0
Demultiplexed Addresses
01
8-bit Data
11-bit: A10 … A0
Multiplexed Addresses
10
16-bit Data
16-bit: A15 … A0
Demultiplexed Addresses
11
16-bit Data
16-bit: A15 … A0
Multiplexed Addresses
The bus configuration (BTYP) for the address windows (BUSCON4 … BUSCON1) is
selected via software, typically during the initialization of the system.
The bus configuration (BTYP) for the default address range (BUSCON0) is selected via
PORT0 during reset, provided that pin EA is low during reset. Otherwise, BUSCON0
may be programmed via software, just like the other BUSCON registers.
The 16-MByte address space of the C164CM is divided into 256 segments of 64 KBytes
each. For multiplexed bus modes the 16/11-bit intra-segment address is output on
PORT0, for demultiplexed bus modes the 16-bit intra-segment address is output on
PORT1. When segmentation is disabled, only one 64-KByte segment can be used and
accessed.
Note: Bit SGTDIS of register SYSCON determines whether or not the CSP register is
saved during interrupt entry (segmentation active or segmentation disabled).
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Derivatives
External Bus Interface
Preferred External Bus Mode
Due to the low pin count of the C164CM, many alternate input/output signals use the pins
of PORT0 and PORT1, thus competing with the External Bus Interface. Many
applications will require the alternate signals to make use of the on-chip peripherals, so
the applicable bus modes are restricted.
Most of the CAPCOM signals use PORT1, so demultiplexed bus modes will only be used
for specific applications.
The standard serial interfaces use the upper pins of PORT0, so 16-bit bus modes can
only be used if the application can do without this serial communication.
8-bit multiplexed bus mode solves this contradiction by restricting the address width to
11 bits. This provides communication via the standard serial interfaces and control of
external peripherals (or small memories) at the same time.
Even though the C164CM’s EBC supports all four bus modes providing access to up to
64 KBytes of external resources, 8-bit multiplexed bus mode represents a good choice
for many applications providing access to 2 KBytes of external resources (most probably
peripheral registers).
Note: Please also refer to the description of PORT0 in Section 7.3.
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Derivatives
External Bus Interface
Multiplexed Bus Modes
In the multiplexed bus modes, both the 16/11-bit intra-segment address and the data use
PORT0. The address is time-multiplexed with the data and must be latched externally.
The width of the required latch depends on the selected data bus width; that is, an 8-bit
data bus requires a byte latch (the address bits A10 … A8 on P0H do not change while
P0L multiplexes address and data), a 16-bit data bus requires a word latch (the least
significant address line A0 is not relevant for word accesses).
The EBC initiates an external access by generating the Address Latch Enable signal
(ALE) and then placing an address on the bus. The falling edge of ALE triggers an
external latch to capture the address. After a period of time during which the address
must have been latched externally, the address is removed from the bus. The EBC now
activates the respective command signal (RD, WR). Data is driven onto the bus either
by the EBC (for write cycles) or by the external memory/peripheral (for read cycles). After
a period of time determined by the access time of the memory/peripheral, data become
valid.
Read cycles: Input data is latched and the command signal is now deactivated. This
causes the accessed device to remove its data from the bus which is then tri-stated
again.
Write cycles: The command signal is now deactivated. The data remain valid on the bus
until the next external bus cycle is started.
Bus Cycle
ALE
BUS (P0)
Address
Data/Instr.
Address
Data
RD
BUS (P0)
WR
MCT02060M
Figure 9-2
User’s Manual
Multiplexed Bus Cycle
9-4
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Derivatives
External Bus Interface
Demultiplexed Bus Modes
In the demultiplexed bus modes, the 16-bit intra-segment address is permanently output
on PORT1 and the data uses PORT0 (16-bit data) or P0L (8-bit data). No address
latches are required.
The EBC initiates an external access by placing an address on the address bus. After a
programmable period of time, the EBC activates the respective command signal (RD,
WR). Data is driven onto the data bus either by the EBC (for write cycles) or by the
external memory/peripheral (for read cycles). After a period of time determined by the
access time of the memory/peripheral, data become valid.
Read cycles: Input data is latched and the command signal is now deactivated. This
causes the accessed device to remove its data from the data bus which is then tri-stated
again.
Write cycles: The command signal is now deactivated. If a subsequent external bus
cycle is required, the EBC places the respective address on the address bus. The data
remain valid on the bus until the next external bus cycle is started.
Bus Cycle
Address (P1)
Address
ALE
Data/Instr.
BUS (P0)
RD
BUS (P0)
Data
WR
MCD02061M
Figure 9-3
User’s Manual
Demultiplexed Bus Cycle
9-5
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Derivatives
External Bus Interface
Switching between Bus Modes
The EBC allows switching between the different bus modes dynamically, i.e. subsequent
external bus cycles may be executed in different ways. Certain address areas may use
multiplexed or demultiplexed buses, an 8-bit or 16-bit data bus, or predefined waitstates.
Changes to the external bus characteristics can be initiated in two different ways:
Switching between predefined address windows automatically selects the bus mode
associated with the respective window. Predefined address windows allow use of
different bus modes without any overhead, but restrict their number to the number of
BUSCONs. However, as BUSCON0 controls all address areas which are not covered by
the other BUSCONs, this allows to have gaps between these windows, which use the
bus mode of BUSCON0.
PORT1 will output the intra-segment address when any of the BUSCON registers
selects a demultiplexed bus mode, even if the current bus cycle uses a multiplexed bus
mode. This allows to have an external address decoder connected to PORT1 only, while
using it for all kinds of bus cycles.
The usage of the BUSCON/ADDRSEL registers is controlled via the issued addresses.
When an access (code fetch or data) is initiated, the respective generated physical
address defines whether the access made internally uses one of the address windows
defined by ADDRSEL4 … 1 or it uses the default configuration in BUSCON0. After
initializing the active registers, they are selected and evaluated automatically by
interpreting the physical address. No additional switching or selecting is necessary
during run time, except when more than the four address windows plus the default are
to be used.
Reprogramming the BUSCON and/or ADDRSEL registers allows either changing the
bus mode for a given address window or changing the size of an address window using
a certain bus mode. Reprogramming allows a great number of different address windows
to be used (more than the BUSCONs available) at the expense of the overhead for
changing the registers and keeping appropriate tables.
Note: Be careful when changing the configuration for an address area that currently
supplies the instruction stream. Due to the internal pipelining, the first instruction
fetch that will use the new configuration depends on the instructions prior to the
configuration change. Special care is required when changing bits like BUSACT,
in order not to cut the instruction stream inadvertently.
Only change the other configuration bits after checking that the respective
application can cope with the intended modification(s).
It is recommended to change ADDRSEL registers only while the respective
BUSACT bit in the associated BUSCON register is cleared.
Switching from demultiplexed to multiplexed bus mode represents a special case.
The bus cycle is started by activating ALE and driving the address to PORT1 as usual,
if another BUSCON register selects a demultiplexed bus. However, in the multiplexed
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Derivatives
External Bus Interface
bus modes, the address is also required on PORT0. In this special case, the address on
PORT0 is delayed by one CPU clock cycle; this delays the complete (multiplexed) bus
cycle and extends the corresponding ALE signal (see Figure 9-4).
This extra time is required to allow the previously selected device (via demultiplexed bus)
to release the data bus, which would be available in a demultiplexed bus cycle.
Demultiplexed
Bus Cycle
Address (P1)
Multiplexed
Bus Cycle
Idle State
Address
Address
ALE
BUS (P0)
Address
Data/Instr.
Data/Instr.
RD
BUS (P0)
Data
Address
Data
WR
MCD02234M
Figure 9-4
Switching from Demultiplexed to Multiplexed Bus Mode
Switching between external resources (such as different peripherals) may incur a
problem if the previously accessed resource needs some time to switch off its output
drivers (after a read) and the resource to be accessed next switches its output drivers on
very quickly. In systems running at higher frequencies, this may lead to a bus conflict (the
switch off delays are normally independent from the clock frequency).
In such a case, an additional waitstate can automatically be inserted when leaving a
certain address window, i.e. when the next cycle accesses a different window. This
waitstate is controlled in the same way as the waitstate when switching from
demultiplexed to multiplexed bus mode, see Figure 9-4.
BUSCON switch waitstates are enabled via bits BSWCx in the BUSCON registers. By
enabling the automatic BUSCON switch waitstate (BSWCx = ‘1’) there is no impact on
the system performance as long as the external bus cycles access the same address
window. Only if the following cycle accesses a different window is a waitstate inserted
between the last access to the previous window and the first access to the new window.
After reset, no BUSCON switch waitstates are selected.
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Derivatives
External Bus Interface
External Data Bus Width
The EBC can operate on 8-bit or 16-bit wide external memory/peripherals. A 16-bit data
bus uses PORT0, while an 8-bit data bus uses only P0L, the lower byte of PORT0. This
saves on address latches, bus transceivers, bus routing, and memory cost at the
expense of transfer time. The EBC can control word accesses on an 8-bit data bus as
well as byte accesses on a 16-bit data bus (read cycles).
Word accesses on an 8-bit data bus are automatically split into two subsequent byte
accesses, where the low byte is accessed first, then the high byte. The assembly of bytes
into words and the disassembly of words into bytes is handled by the EBC and is
transparent to the CPU and the programmer.
Byte accesses on a 16-bit data bus require that the upper and lower half of the memory
can be accessed individually. Because of the lack of the BHE signal the C164CM cannot
select individual bytes on external resources.1)
When reading bytes from an external 16-bit device, whole words may be read and the
C164CM automatically selects the byte to be input and discards the other. However,
care must be taken when reading devices that change state when being read, such as
FIFOs, interrupt status registers, etc.
Writing bytes to an external 16-bit device should be avoided. A0 indicates the selected
byte (high or low) but often is not used in 16-bit systems. There is also no way to
distinguish low-byte writes from word-writes, due to the missing BHE. The C164CM will
write the respective byte value to both halves of the 16-bit data bus.
Table 9-2
Bus Mode versus Performance
Bus Mode
Transfer Rate
(Speed factor for byte/
word/dword access)
System Requirements
Free IO
Lines
8-bit Multiplexed
Very low
Low (8-bit latch, byte bus)
P1H, P1L,
P0H.7-3
8-bit Demultipl.
Low
(1 / 2 / 4)
16-bit Multiplexed High
(1.5 / 1.5 / 3)
16-bit Demultipl.
Very high
(1.5 / 3 / 6)
(1 / 1 / 2)
Very low (no latch, byte bus) P0H
High (16-bit latch, word bus) P1H, P1L
Low (no latch, word bus)
---
Note: PORT1 becomes available for general purpose IO, when none of the BUSCON
registers selects a demultiplexed bus mode.
1)
Byte accesses are supported for on-chip resources, except for the SFRs.
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Derivatives
External Bus Interface
9.3
Programmable Bus Characteristics
Important timing characteristics of the external bus interface are user programmable to
allow adaptation to a wide range of different external bus and memory configurations
with different types of memories and/or peripherals.
The following parameters of an external bus cycle are programmable:
• ALE Control defines the ALE signal length and the address hold time after its falling
edge
• Memory Cycle Time (extendable with 1 … 15 waitstates) defines the allowable access
time
• Memory Tri-State Time (extendable with 1 waitstate) defines the time for a data
driver to float
• Read/Write Delay Time defines when a command is activated after the falling edge of
ALE
Note: Internal accesses are executed with maximum speed and therefore are not
programmable.
External accesses use the slowest possible bus cycle after reset. The bus cycle
timing may then be optimized by the initialization software.
ALE
ADDR
RD/WR
DATA
ALE
ADDR
RD/WR
DATA
ALECTL
Figure 9-5
User’s Manual
MCTC
MTTC
MCD02225
Programmable External Bus Cycle
9-9
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Derivatives
External Bus Interface
ALE Length Control
The length of the ALE signal and the address hold time after its falling edge are
controlled by the ALECTLx bits in the BUSCON registers. When bit ALECTL is set to ‘1’,
external bus cycles accessing the respective address window will have their ALE signals
prolonged by half a CPU clock (1 TCL). Also, the address hold time after the falling edge
of ALE (on a multiplexed bus) will be prolonged by half a CPU clock, so the data transfer
within a bus cycle refers to the same CLKOUT edges as usual (the data transfer is
delayed by one CPU clock). This allows more time for the address to be latched.
Note: ALECTL0 is ‘1’ after reset to select the slowest possible bus cycle, the other
ALECTLx are ‘0’ after reset.
Normal Multiplexed
Bus Cycle
Lengthened Multiplexed
Bus Cycle
ALE
Setup
BUS (P0)
Address
Data/Instr.
Hold
Address
Data/Instr.
RD
BUS (P0)
Address
Data
Address
Data
WR
MCD02235M
Figure 9-6
User’s Manual
ALE Length Control
9-10
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External Bus Interface
Programmable Memory Cycle Time
The C164CM allows the user to adjust the controller’s external bus cycles to the access
time of the respective memory or peripheral. This access time is the total time required
to move the data to the destination. It represents the period of time during which the
controller’s signals do not change.
Bus Cycle
ALE
BUS (P0)
Data/Instr.
Address
RD
BUS (P0)
Data
Address
WR
MCTC Wait States (1...15)
Figure 9-7
MCT02063M
Memory Cycle Time
The external bus cycles of the C164CM can be extended for a memory or peripheral
which cannot keep pace with the controller’s maximum speed. This is accomplished by
introducing wait states during the access (see Figure 9-7). During these memory cycle
time wait states, the CPU is idle if this access is required for the execution of the current
instruction.
The memory cycle time wait states can be programmed in increments of one CPU clock
(2 TCL) within a range from 0 to 15 (default after reset) via the MCTC fields of the
BUSCON registers. 15 - <MCTC> waitstates will be inserted.
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External Bus Interface
Programmable Memory Tri-State Time
The C164CM allows the user to adjust the time between two subsequent external
accesses to account for the tri-state time of the external device. The tri-state time defines
when the external device releases the bus after deactivation of the read command (RD).
Bus Cycle
ALE
BUS (P0)
Address
Data/Instr.
RD
MTTC Wait State
MCT02065M
Figure 9-8
Memory Tri-State Time
The output of the next address on the external bus can be delayed for a memory or
peripheral which needs more time to switch off its bus drivers. This is accomplished by
introducing a wait state after the previous bus cycle (see Figure 9-8). During this
memory tri-state time wait state, the CPU is not idle, so CPU operations will be slowed
down only if a subsequent external instruction or data fetch operation is required during
the next instruction cycle.
The memory tri-state time waitstate requires one CPU clock (2 TCL) and is controlled via
the MTTCx bits of the BUSCON registers. A waitstate will be inserted if bit MTTCx is ‘0’
(default after reset).
Note: External bus cycles in multiplexed bus modes implicitly add one tri-state time
waitstate in addition to the programmable MTTC waitstate.
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Derivatives
External Bus Interface
Read/Write Signal Delay
The C164CM allows the user to adjust the timing of the read and write commands to
account for timing requirements of external peripherals. The read/write delay controls the
time between the falling edge of ALE and the falling edge of the command. Without read/
write delay, the falling edges of ALE and command(s) coincide (except for propagation
delays). With the delay enabled, the command(s) become active half a CPU clock
(1 TCL) after the falling edge of ALE.
The read/write delay does not extend the memory cycle time, and does not slow down
the controller in general. In multiplexed bus modes, however, the data drivers of an
external device may conflict with the C164CM’s address when the early RD signal is
used. Therefore, multiplexed bus cycles should always be programmed with read/write
delay.
The read/write delay is controlled via the RWDCx bits in the BUSCON registers. The
command(s) will be delayed if bit RWDCx is ‘0’ (default after reset).
Early WR Signal Deactivation
The duration of an external write access can be shortened by one TCL. The WR signal
is activated (driven low) in the standard way, but can be deactivated (driven high) one
TCL earlier than defined in the standard timing. In this case, the data output drivers will
also be deactivated one TCL earlier.
This is especially useful in systems which operate on higher CPU clock frequencies and
employ external modules (memories, peripherals, etc.) which switch on their own data
drivers very quickly in response to signals such as a chip select.
Conflicts between the output drivers of the C164CM and the external peripheral’s output
drivers can be avoided by selecting early WR for the C164CM.
Note: Ensure that the reduced WR low time still matches the requirements of the
external peripheral/memory.
Early WR deactivation is controlled via the EWENx bits in the BUSCON registers. The
WR signal will be shortened if bit EWENx is ‘1’ (default after reset is a standard WR
signal, that is, EWENx = ‘0’).
User’s Manual
9-13
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
Bus Cycle
ALE
BUS (P0)
Data/Instr.
1)
RD
BUS (P0)
Data
Address
2)
3)
4)
WR
Read/Write
Delay
Early Write
MCT04005M
1) The data drivers from the previous bus cycle should be disabled when the RD signal becomes active.
2) Data drivers are disabled in an early-write cycle.
3) Data drivers are disabled in a demultiplexed normal-write cycle.
4) Data drivers are disabled in a multiplexed normal-write cycle.
Figure 9-9
User’s Manual
Read/Write Signal Duration Control
9-14
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
9.4
Controlling the External Bus Controller
A set of registers controls the functions of the EBC. General features such as
segmentation and internal ROM mapping are controlled via register SYSCON. Bus cycle
properties such as length of ALE, external bus mode, read/write delay, and waitstates
are controlled via registers BUSCON4 … BUSCON0. Four of these registers (BUSCON4
… BUSCON1) have an address select register (ADDRSEL4 … ADDRSEL1) associated
with them. This allows specifying up to four address areas and the individual bus
characteristics within these areas. All accesses not covered by these four areas are then
controlled via BUSCON0. This allows memory components or peripherals to be used
with different interfaces within the same system while optimizing accesses to each of
them.
SYSCON
System Control Register
15
14
13
12
11
SFR (FF12H/89H)
10
ROM SGT ROM
S1 DIS EN
STKSZ
rw
rw
rw
rwh
Reset Value: 0XX0H
9
8
7
6
5
-
CLK
EN
-
-
-
-
rw
-
-
-
4
3
2
1
BD
OWD RST
VISIDIS EN XPEN BLE
rwh rw
rw
rw
Bit
Function
VISIBLE
Visible Mode Control
0:
Accesses to XBUS peripherals are done internally.
1:
XBUS peripheral accesses are made visible on the external pins.
0
-
XPEN
XBUS Peripheral Enable Bit
0:
Accesses to the on-chip X-Peripherals and their functions are
disabled.
1:
The on-chip X-Peripherals are enabled and can be accessed.
BDRSTEN Bidirectional Reset Enable Bit
0:
Pin RSTIN is an input only.
1:
Pin RSTIN is pulled low during the internal reset sequence
after any reset.
OWDDIS
CLKEN
Oscillator Watchdog Disable Bit
0:
The on-chip oscillator watchdog is enabled and active.
1:
The on-chip oscillator watchdog is disabled and the CPU clock is
always fed from the oscillator input.
System Clock Output Enable (CLKOUT)
0:
CLKOUT disabled: pin may be used for general purpose IO or
for signal FOUT.
1:
CLKOUT enabled: pin outputs the system clock signal.
User’s Manual
9-15
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
Bit
ROMEN
Function
Internal ROM Enable (Set according to pin EA during reset)
0:
Internal program memory disabled,
accesses to the ROM area use the external bus.
1:
Internal program memory enabled.
SGTDIS
Segmentation Disable/Enable Control
0:
Segmentation enabled.
(CSP is saved/restored during interrupt entry/exit)
1:
Segmentation disabled (Only IP is saved/restored).
ROMS1
Internal ROM Mapping
0:
Internal ROM area mapped to segment 0 (00’0000H … 00’7FFFH).
1:
Internal ROM area mapped to segment 1 (01’0000H … 01’7FFFH).
STKSZ
System Stack Size
Selects the size of the system stack (in the internal RAM)
from 32 to 1024 words.
Note: Register SYSCON cannot be changed after execution of the EINIT instruction.
Bit SGTDIS controls the correct stack operation (push/pop of CSP or not) during
traps and interrupts.
The layout of the BUSCON registers and ADDRSEL registers is identical (respectively).
Registers BUSCON4 … BUSCON1 control the selected address windows and are
completely under software control. Register BUSCON0, which for example, is also used
for the very first code access after reset, is partly controlled by hardware; that is, it is
initialized via PORT0 during the reset sequence. This hardware control allows defining
an appropriate external bus for systems where no internal program memory is provided.
User’s Manual
9-16
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
BUSCON0
Bus Control Register 0
15
14
13
12
-
-
-
-
-
-
-
-
11
SFR (FF0CH/86H)
10
14
13
12
-
-
-
-
-
-
-
-
14
13
12
-
-
-
-
-
-
-
-
11
10
14
13
12
-
-
-
-
-
-
-
-
11
14
13
12
-
-
-
-
-
-
-
-
8
10
9
8
rwh
5
4
BTYP
rw
BTYP
rw
9
8
7
5
BTYP
rw
4
9
8
7
ALE EW
BSW BUS
CTL EN4
C4 ACT
4
4
rw
rw
rw
rw
BTYP
rw
2
1
0
MCTC
rw
Reset Value: 0000H
5
4
3
MTT RWD
C2 C2
2
1
0
MCTC
rw
rw
Reset Value: 0000H
5
4
3
MTT RWD
C3 C3
rw
6
3
rw
2
1
0
MCTC
rw
SFR (FF1AH/8DH)
10
0
rw
MTT RWD
C1 C1
rw
6
1
MCTC
rw
SFR (FF18H/8CH)
10
2
Reset Value: 0000H
rw
6
3
MTT RWD
C0 C0
rw
6
7
ALE EW
BSW BUS
ACT
CTL EN3
C3
3
3
rw
rw
rw
rw
11
BTYP
7
ALE EW
BSW BUS
ACT
CTL EN2
C2
2
2
rw
rw
rw
rw
11
6
SFR (FF16H/8BH)
BUSCON4
Bus Control Register 4
15
9
ALE EW
BSW BUS
ACT
CTL EN1
C1
1
1
rw
rw
rw
rw
BUSCON3
Bus Control Register 3
15
7
SFR (FF14H/8AH)
BUSCON2
Bus Control Register 2
15
8
ALE EW
BSW BUS
ACT
CTL EN0
C0
0
0
rw rwh rwh rw
BUSCON1
Bus Control Register 1
15
9
Reset Value: 0XX0H
rw
Reset Value: 0000H
5
4
MTT RWD
C4 C4
rw
rw
3
2
1
0
MCTC
rw
Note: BUSCON0 is initialized with 00C0H if pin EA is high during reset. If pin EA is low
during reset, bits BUSACT0 and ALECTL0 are set (‘1’) and bit field BTYP is loaded
with the bus configuration selected via PORT0.
User’s Manual
9-17
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
Bit
Function
MCTC
Memory Cycle Time Control (Number of memory cycle time wait states)
0000: 15 waitstates
…
(Number = 15 - <MCTC>)
1111: No waitstates
RWDCx
Read/Write Delay Control for BUSCONx
0:
With rd/wr delay: activate command 1 TCL after falling edge of ALE
1:
No rd/wr delay: activate command with falling edge of ALE
MTTCx
Memory Tristate Time Control
0:
1 waitstate
1:
No waitstate
BTYP
External Bus Configuration
00: 8-bit Demultiplexed Bus
01: 8-bit Multiplexed Bus
10: 16-bit Demultiplexed Bus
11: 16-bit Multiplexed Bus
Note: For BUSCON0 BTYP is defined via PORT0 during reset.
EWENx
Early Write Enable
0:
Normal WR signal
1:
Early write: The WR signal is deactivated and write data is tristated
one TCL earlier
ALECTLx ALE Lengthening Control
0:
Normal ALE signal
1:
Lengthened ALE signal
BUSACTx Bus Active Control
0:
External bus disabled
1:
External bus enabled within respective address window (ADDRSEL)
BSWCx
1)
BUSCON Switch Control
0:
Address windows are switched immediately
1:
A tristate waitstate is inserted if the next bus cycle accesses a window
different from the one controlled by this BUSCON register.1)
A BUSCON switch waitstate is enabled by bit BUSCONx.BSWCx of the address window that is left.
User’s Manual
9-18
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
ADDRSEL1
Address Select Register 1
15
14
13
12
11
SFR (FE18H/0CH)
10
9
14
13
12
11
14
13
12
11
14
13
12
11
5
4
3
2
1
rw
rw
SFR (FE1AH/0DH)
10
9
8
7
6
5
4
3
2
1
RGSZ
rw
rw
SFR (FE1CH/0EH)
10
9
8
7
6
5
4
3
2
1
RGSZ
rw
rw
SFR (FE1EH/0FH)
9
8
7
6
0
Reset Value: 0000H
RGSAD
10
0
Reset Value: 0000H
RGSAD
ADDRSEL4
Address Select Register 4
15
6
RGSZ
ADDRSEL3
Address Select Register 3
15
7
RGSAD
ADDRSEL2
Address Select Register 2
15
8
Reset Value: 0000H
0
Reset Value: 0000H
5
4
3
2
1
RGSAD
RGSZ
rw
rw
Bit
Function
RGSZ
Range Size Selection
Defines the size of the address area controlled by the respective
BUSCONx/ADDRSELx register pair. See Table 9-3.
RGSAD
Range Start Address
Defines the upper bits of the start address of the respective address
area. See Table 9-3.
0
Note: There is no register ADDRSEL0 because register BUSCON0 controls all external
accesses outside the four address windows of BUSCON4 … BUSCON1 within the
complete address space.
User’s Manual
9-19
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
Definition of Address Areas
The four register pairs BUSCON4/ADDRSEL4 … BUSCON1/ADDRSEL1 allow
definition of four separate address areas within the address space of the C164CM.
Within each of these address areas, external accesses can be controlled by one of the
four different bus modes. They are independent of each other and of the bus mode
specified in register BUSCON0. Each ADDRSELx register, so to say, cuts out an
address window within which the parameters in register BUSCONx are used to control
external accesses. The range start address of such a window defines the upper address
bits which are not used within the address window of the specified size (see Table 9-3).
For a given window size, only those upper address bits of the start address are used
(marked “R”) which are not implicitly used for addresses inside the window. The lower
bits of the start address (marked “x”) are disregarded.
Table 9-3
Address Window Definition
Bit field RGSZ Resulting Window Size
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
11xx
User’s Manual
4 KByte
8 KByte
16 KByte
32 KByte
64 KByte
128 KByte
256 KByte
512 KByte
1 MByte
2 MByte
4 MByte
8 MByte
Reserved.
Relevant Bits (R) of Start Addr. (A12 …)
R
R
R
R
R
R
R
R
R
R
R
R
9-20
R
R
R
R
R
R
R
R
R
R
R
x
R
R
R
R
R
R
R
R
R
R
x
x
R
R
R
R
R
R
R
R
R
x
x
x
R
R
R
R
R
R
R
R
x
x
x
x
R
R
R
R
R
R
R
x
x
x
x
x
R
R
R
R
R
R
x
x
x
x
x
x
R
R
R
R
R
x
x
x
x
x
x
x
R
R
R
R
x
x
x
x
x
x
x
x
R
R
R
x
x
x
x
x
x
x
x
x
R
R
x
x
x
x
x
x
x
x
x
x
R
x
x
x
x
x
x
x
x
x
x
x
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
Address Window Arbitration
The address windows which can be defined within the address space of the C164CM
may partly overlap each other. Thus, for example, small areas may be cut out of bigger
windows in order to effectively utilize external resources, especially within segment 0.
For each access, the EBC compares the current address with all address select registers
(programmable ADDRSELx and hardwired XADRSx). This comparison is done in four
priority levels.
Priority 1: The hardwired XADRSx registers are evaluated first. A match with one of
these registers directs the access to the respective X-Peripheral using the
corresponding XBCONx register and ignoring all other ADDRSELx
registers.
Priority 2: Registers ADDRSEL2 and ADDRSEL4 are evaluated before ADDRSEL1
and ADDRSEL3, respectively. A match with one of these registers directs
the access to the respective external area using the corresponding
BUSCONx register and ignoring registers ADDRSEL1/3 (see Figure 9-9).
Priority 3: A match with registers ADDRSEL1 or ADDRSEL3 directs the access to the
respective external area using the corresponding BUSCONx register.
Priority 4: If there is no match with any XADRSx or ADDRSELx register, the access to
the external bus uses register BUSCON0.
XBCON0
BUSCON2
BUSCON4
BUSCON1
BUSCON3
BUSCON0
Active Window
Inactive Window
MCA04368
Figure 9-10 Address Window Arbitration
Note: Only the indicated overlaps are defined. All other overlaps lead to erroneous bus
cycles; for example, ADDRSEL4 may not overlap ADDRSEL2 or ADDRSEL1. The
hardwired XADRSx registers are defined as non-overlapping.
User’s Manual
9-21
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
RP0H
Reset Value of P0H
15
14
13
12
SFR (F108H/84H)
11
10
9
8
7
6
Reset Value: - - XXH
5
4
3
2
1
0
CLKCFG
-
-
-
rh
-
-
-
Bit
Function
CLKCFG
Clock Generation Mode Configuration
These pins define the clock generation mode, i.e. the mechanism by
which the internal CPU clock is generated from the externally applied
(XTAL1) input clock.
Note: RP0H is initialized during the reset configuration and permits to check the current
configuration.
This configuration can be changed via register RSTCON (see Section 20.5).
The layout of register RP0H is the same as for other devices of the C166 Family.
Precautions and Hints
• The external bus interface is enabled as long as at least one of the BUSCON registers
has its BUSACT bit set.
• PORT1 will output the intra-segment address as long as at least one of the BUSCON
registers selects a demultiplexed external bus, even for multiplexed bus cycles.
• Not all address windows defined via registers ADDRSELx may overlap each other.
The operation of the EBC will be erroneous in such a case. See “Address Window
Arbitration” on Page 9-21.
• The address windows defined via registers ADDRSELx may overlap internal address
areas. Internal accesses will be executed in this case.
• For any access to an internal address area, the EBC will remain inactive (see
Section 9.5).
User’s Manual
9-22
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
9.5
EBC Idle State
When the external bus interface is enabled, but no external access is currently executed,
the EBC is idle. As long as only internal resources (from an architecture point of view)
such as IRAM, GPRs or SFRs, etc. are used, the external bus interface does not change
(see Table 9-4).
Accesses to on-chip X-Peripherals are also controlled by the EBC. However, even
though an X-Peripheral appears like an external peripheral to the controller, the
respective accesses do not generate valid external bus cycles.
Due to timing constraints, address and write data of an XBUS cycle are reflected on the
external bus interface (see Table 9-4). The “address” mentioned above includes PORT1
and ALE which also pulses for an XBUS cycle.
The external control signals (RD and WR) remain inactive (high).
Table 9-4
Status Of The External Bus Interface During EBC Idle State
Pins
Internal Accesses only
XBUS Accesses
PORT0
Tristated (floating)
Tristated (floating) for read accesses
XBUS write data for write accesses
PORT1
Last used external address
(if used for the bus interface)
Last used XBUS address
(if used for the bus interface)
ALE
Inactive (low)
Pulses as defined for X-Peripheral
RD
Inactive (high)
Inactive (high)1)
WR
Inactive (high)
Inactive (high)1)
1)
Used and driven in visible mode.
User’s Manual
9-23
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
9.6
The XBUS Interface
The C164CM provides an on-chip interface, the XBUS interface, via which integrated
customer/application specific peripherals can be connected to the standard controller
core. The XBUS is an internal representation of the external bus interface and is
operated in the same way.
For each peripheral on the XBUS (X-Peripheral) there is a separate address window
controlled by a register pair XBCONx/XADRSx (similar to registers BUSCONx and
ADDRSELx). Because an interface to a peripheral is represented in many cases by just
a few registers, the XADRSx registers partly select smaller address windows than the
standard ADDRSEL registers. As the XBCONx/XADRSx (register pairs control
integrated peripherals rather than externally connected ones, they are fixed by mask
programming rather than being user programmable.
X-Peripheral accesses provide the same choices as external accesses; so, these
peripherals may be bytewide or wordwide. Because the on-chip connection can be
implemented very efficiently, for performance reasons, X-Peripherals are implemented
only with a separate address bus (in demultiplexed bus mode). Interrupt nodes are
provided for X-Peripherals to be integrated.
Note: If you plan to develop a peripheral of your own to be integrated into a C164CM
device to create a customer specific version, please ask for the specification of the
XBUS interface and for further support.
User’s Manual
9-24
V1.0, 2002-02
C164CM/C164SM
Derivatives
External Bus Interface
9.6.1
Accessing the On-chip XBUS Peripherals
Enabling of XBUS Peripherals
After reset, all on-chip XBUS peripherals are disabled. In order to be usable, an XBUS
peripheral must be enabled via the global enable bit XPEN in register SYSCON.
Table 9-5 summarizes the XBUS peripherals and also the number of waitstates which
are used when accessing the respective peripheral.
Table 9-5
XBUS Peripherals in the C164CM
Associated XBUS Peripheral
CAN1
Waitstates
2
Visible Mode
The C164CM can mirror on-chip access cycles to its XBUS peripherals so these
accesses can be observed or recorded by the external system. This function is enabled
via bit VISIBLE in register SYSCON.
Accesses to XBUS peripherals also use the EBC. Due to timing constraints the address
bus will change for all accesses using the EBC.
Note: As XBUS peripherals use demultiplexed bus cycles, the respective address is
driven on PORT1 in visible mode, even if the external system uses MUX buses
only.
If visible mode is activated, accesses to on-chip XBUS peripherals (including control
signals RD, WR) are mirrored to the bus interface. Accesses to internal resources
(program memory, IRAM, GPRs) do not use the EBC and cannot be mirrored to outside.
If visible mode is deactivated, however, no control signals (RD, WR) will be activated,
that is, there will be no valid external bus cycles.
Note: Visible mode can only work if the external bus is enabled at all.
9.6.2
External Accesses to XBUS Peripherals
The on-chip XBUS peripherals of the C164CM can be accessed from outside via the
external bus interface under certain circumstances. In emulation mode the XBUS
peripherals are controlled by the bondout-chip.
User’s Manual
9-25
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
10
General Purpose Timer Unit
The General Purpose Timer Unit GPT1 has a very flexible multifunctional timer structure
which may be used for timing, event counting, pulse width measurement, pulse
generation, frequency multiplication, and other purposes.
Block GPT1 contains 3 timers/counters with a maximum resolution of 16 TCL. Each
timer may operate independently in a number of different modes such as gated timer or
counter mode, or may be concatenated with another timer of the same block. The
auxiliary timers of GPT1 may optionally be configured as reload or capture registers for
the core timer. GPT1 has alternate input/output functions and specific interrupts
associated with it.
10.1
Timer Block GPT1
From a programmer’s point of view, the GPT1 block is composed of a set of Special
Function Registers (SFRs) as summarized in Figure 10-1. Those portions of port and
direction registers which are used for alternate functions by the GPT1 block are shaded.
Ports & Direction Control
Alternate Functions
Data Registers
Control Registers
Interrupt Control
T2
T2CON
T2IC
T3
T3CON
T3IC
T4
T4CON
T4IC
P5
P5DIDIS
T2IN/P5.6
T3IN/P5.3
T4IN/P5.7
T2EUD/P5.4
T3EUD/P5.2
T4EUD/P5.5
P5
P5DIDIS
Port 5 Data Register
Port 5 Digital Input Disable Register
T2CON
T3CON
T4CON
GPT1 Timer 2 Control Register
GPT1 Timer 3 Control Register
GPT1 Timer 4 Control Register
T2
T3
T4
T2IC
T3IC
T4IC
GPT1 Timer 2 Register
GPT1 Timer 3 Register
GPT1 Timer 4 Register
GPT1 Timer 2 Interrupt Control Register
GPT1 Timer 3 Interrupt Control Register
GPT1 Timer 4 Interrupt Control Register
MCA05135
Figure 10-1 SFRs and Port Pins Associated with Timer Block GPT1
User’s Manual
10-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
All three timers of block GPT1 (T2, T3, T4) can run in 4 basic modes: timer, gated timer,
counter, and incremental interface mode. All timers can count either up or down. Each
timer has an alternate input function pin (TxIN) associated with it which serves as the
gate control in gated timer mode or as the count input in counter mode. The count
direction (Up/Down) may be programmed via software or may be dynamically altered by
a signal at an external control input pin. Each overflow/underflow of core timer T3 is
latched in the toggle FlipFlop T3OTL and may be indicated on an alternate output
function pin. The auxiliary timers T2 and T4 may additionally be concatenated with the
core timer or may be used as capture or reload registers for the core timer.
The current contents of each timer can be read or modified by the CPU by accessing the
corresponding timer registers T2, T3, or T4, located in the non-bitaddressable SFR
space. When any of the timer registers is written to by the CPU in the state immediately
preceding a timer increment, decrement, reload, or capture operation, the CPU write
operation has priority in order to guarantee correct results.
U/D
T2EUD
fCPU
2n : 1
T2IN
T2
Mode
Control
Interrupt
Request
(T2IR)
GPT1 Timer T2
Reload
Capture
fCPU
Interrupt
Request
(T3IR)
2n : 1
T3
Mode
Control
T3IN
Toggle FF
GPT1 Timer T3
T3OTL
U/D
T3EUD
Other
Timers
Capture
Reload
T4IN
fCPU
2n : 1
T4
Mode
Control
GPT1 Timer T4
U/D
T4EUD
Interrupt
Request
(T4IR)
MCT04825_4
n = 3 … 10
Figure 10-2 GPT1 Block Diagram
User’s Manual
10-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
10.1.1
GPT1 Core Timer T3
The core timer T3 is configured and controlled via its bitaddressable control register
T3CON.
T3CON
Timer 3 Control Register
SFR (FF42H/A1H)
15
14
13
12
11
10
9
-
-
-
-
-
T3
OTL
-
-
-
-
-
-
rwh
-
8
7
T3
T3
UDE UD
rw
rw
6
Reset Value: 0000H
5
4
3
2
1
T3R
T3M
T3I
rw
rw
rw
Bit
Function
T3I
Timer 3 Input Selection
Depends on the operating mode, see respective sections.
T3M
Timer 3 Mode Control (Basic Operating Mode)
000: Timer Mode
001: Counter Mode
010: Gated Timer with Gate active low
011: Gated Timer with Gate active high
100: Reserved. Do not use this combination.
101: Reserved. Do not use this combination.
110: Incremental Interface Mode
111: Reserved. Do not use this combination.
T3R
Timer 3 Run Bit
0:
Timer/Counter 3 stops
1:
Timer/Counter 3 runs
T3UD
Timer 3 Up/Down Control1)
T3UDE
Timer 3 External Up/Down Enable1)
T3OTL
Timer 3 Output Toggle Latch
Toggles on each overflow/underflow of T3. Can be set or reset by
software.
1)
0
For the effects of bits T3UD and T3UDE, refer to the direction Table 10-1.
Timer 3 Run Bit
The timer can be started or stopped by software through bit T3R (Timer T3 Run Bit). If
T3R = ‘0’, the timer stops. Setting T3R to ‘1’ will start the timer. In gated timer mode, the
timer will run only if T3R = ‘1’ and the gate is active (high or low, as programmed).
User’s Manual
10-3
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Count Direction Control
The count direction of the core timer can be controlled either by software or by the
external input pin T3EUD (Timer T3 External Up/Down Control Input), an alternate input
function of port pin P5.2. These options are selected by bits T3UD and T3UDE in control
register T3CON. When the up/down control is provided by software (bit T3UDE = ‘0’),
the count direction can be altered by setting or clearing bit T3UD. When T3UDE = ‘1’, pin
T3EUD is selected to be the controlling source of the count direction. However, bit T3UD
can still be used to reverse the actual count direction, as shown in Table 10-1. If
T3UD = ‘0’ and pin T3EUD shows a low level, the timer is counting up. With a high level
at T3EUD, the timer is counting down. If T3UD = ‘1’, a high level at pin T3EUD specifies
counting up, and a low level specifies counting down. The count direction can be
changed regardless of whether or not the timer is running.
Table 10-1
GPT1 Core Timer T3 Count Direction Control
Pin TxEUD
Bit TxUDE
Bit TxUD
Count Direction
X
0
0
Count Up
X
0
1
Count Down
0
1
0
Count Up
1
1
0
Count Down
0
1
1
Count Down
1
1
1
Count Up
Note: Direction control works the same way for core timer T3 and for auxiliary timers T2
and T4. Therefore, the pins and bits are named Tx …
User’s Manual
10-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Timer 3 Output Toggle Latch
An overflow or underflow of timer T3 will clock the toggle bit T3OTL in control register
T3CON. T3OTL can also be set or reset by software.
Additionally, T3OTL can be used in conjunction with the timer over/underflows as an
input for the counter function or as a trigger source for the reload function of the auxiliary
timers T2 and T4. An internal connection is provided for this option.
Timer 3 in Timer Mode
Timer mode for the core timer T3 is selected by setting bit field T3M in register T3CON
to ‘000B’. In this mode, T3 is clocked with the internal system clock (CPU clock) divided
by a programmable prescaler, which is selected by bit field T3I. The input frequency fT3
for timer T3 and its resolution rT3 are scaled linearly with lower clock frequencies fCPU,
as can be seen from the following formula:
fT3 =
fCPU
,
8 × 2<T3I>
rT3 [µs] =
8 × 2<T3I>
fCPU [MHz]
Txl
fCPU
2n : 1
Up/
Down
TxR
TxUD
Interrupt
Request
(TxIR)
Core Timer Tx
TxOTL
To auxiliary
Timers
0
MUX
TxEUD
XOR
1
TxUDE
MCB02028d
T3EUD = P5.2
x=3
n = 3 … 10
Figure 10-3 Block Diagram of Core Timer T3 in Timer Mode
Timer input frequencies, resolution, and periods resulting from the selected prescaler
option are listed in Table 10-2. This table also applies to the Gated Timer Mode of T3
and to the auxiliary timers T2 and T4 in timer and gated timer mode. Note that some
numbers may be rounded to 3 significant digits.
User’s Manual
10-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Table 10-2
GPT1 Timer Input Frequencies, Resolution and Periods @ 20 MHz
fCPU = 20 MHz
Timer Input Selection T2I/T3I/T4I
000B
001B
010B
011B
100B
101B
110B
111B
Prescaler
Factor
8
16
32
64
128
256
512
1024
Input
Frequency
2.5
MHz
1.25
MHz
625
kHz
312.5
kHz
156.25 78.125 39.06
kHz
kHz
kHz
Resolution
400 ns
800 ns 1.6 µs
3.2 µs
6.4 µs
Period
26.2 ms 52.5 ms 105 ms 210 ms 420 ms 840 ms 1.68 s
Table 10-3
19.53
kHz
12.8 µs 25.6 µs 51.2 µs
3.36 s
GPT1 Timer Input Frequencies, Resolution and Periods @ 25 MHz
fCPU = 25 MHz
Timer Input Selection T2I/T3I/T4I
000B
001B
010B
011B
100B
101B
110B
111B
Prescaler
Factor
8
16
32
64
128
256
512
1024
Input
Frequency
3.125
MHz
1.56
MHz
781.25
kHz
390.62 195.3
kHz
kHz
97.65
kHz
48.83
kHz
24.42
kHz
Resolution
320 ns
640 ns 1.28 µs 2.56 µs 5.12 µs 10.2 µs 20.5 µs 41.0 µs
Period
21.0 ms 41.9 ms 83.9 ms 168 ms 336 ms 671 ms 1.34 s
Table 10-4
2.68 s
GPT1 Timer Input Frequencies, Resolution and Periods @ 33 MHz
fCPU = 33 MHz
Timer Input Selection T2I/T3I/T4I
000B
001B
010B
011B
100B
101B
110B
111B
Prescaler
Factor
8
16
32
64
128
256
512
1024
Input
Frequency
4.125
MHz
2.0625 1.031
MHz
MHz
515.62 257.81 128.91 64.45
kHz
kHz
kHz
kHz
Resolution
242 ns
485 ns 970 ns
1.94 µs 3.88 µs 7.76 µs 15.5 µs 31.0 µs
Period
15.9 ms 31.8 ms 63.6 ms 127 ms 254 ms 508 ms 1.02 s
User’s Manual
10-6
32.23
kHz
2.03 s
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Timer 3 in Gated Timer Mode
Gated timer mode for the core timer T3 is selected by setting bit field T3M in register
T3CON to ‘010B’ or ‘011B’. Bit T3M.0 (T3CON.3) selects the active level of the gate
input. The same options for the input frequency are available in gated timer mode as in
timer mode. However, the input clock to the timer in this mode is gated by the external
input pin T3IN (Timer T3 External Input).
To enable this operation, pin T3IN must be configured as input, that is, the corresponding
direction control bit must contain ‘0’.
TxI
fCPU
TxIN
2n : 1
MUX
Core Timer Tx
TxM
TxUD
TxOTL
Up/
Down
TxR
0
Interrupt
Request
(TxIR)
MUX
TxEUD
XOR
To auxiliary
Timers
1
MCB02029b
TxUDE
T3IN = P5.3
T3EUD = P5.2
x=3
n = 3 … 10
Figure 10-4 Block Diagram of Core Timer T3 in Gated Timer Mode
If T3M.0 = ‘0’, the timer is enabled when T3IN shows a low level. A high level at this pin
stops the timer. If T3M.0 = ‘1’, pin T3IN must have a high level in order to enable the
timer. Additionally, the timer can be turned on or off by software using bit T3R. The timer
will only run, if T3R = ‘1’ and the gate is active. It will stop if either T3R = ‘0’ or the gate
is inactive.
Note: A transition of the gate signal at pin T3IN does not cause an interrupt request.
User’s Manual
10-7
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Timer 3 in Counter Mode
Counter mode for the core timer T3 is selected by setting bit field T3M in register T3CON
to ‘001B’. In counter mode timer T3 is clocked by a transition at the external input pin
T3IN. The event causing an increment or decrement of the timer can be a positive, a
negative, or both a positive and a negative transition at this pin. Bit field T3I in control
register T3CON selects the triggering transition (see Table 10-5).
Edge
Select
TxIN
Core Timer Tx
TxOTL
To auxiliary
Timers
Up/
Down
TxR
Txl
TxUD
0
Interrupt
Request
(TxIR)
MUX
XOR
TxEUD
1
TxUDE
MCB02030c
T3IN = P5.3
T3EUD = P5.2
x=3
Figure 10-5 Block Diagram of Core Timer T3 in Counter Mode
Table 10-5
GPT1 Core Timer T3 (Counter Mode) Input Edge Selection
T3I
Triggering Edge for Counter Increment/Decrement
000
None. Counter T3 is disabled
001
Positive transition (rising edge) on T3IN
010
Negative transition (falling edge) on T3IN
011
Any transition (rising or falling edge) on T3IN
1XX
Reserved. Do not use this combination
For counter operation, pin T3IN must be configured as input; the respective direction
control bit DPx.y must be set to ‘0’. The maximum input frequency allowed in counter
mode is fCPU/16. To ensure that a transition of the count input signal applied to T3IN is
recognized correctly, its level should be held high or low for at least 8 fCPU cycles before
it changes.
User’s Manual
10-8
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Timer 3 in Incremental Interface Mode
Incremental Interface Mode for the core timer T3 is selected by setting bit field T3M in
register T3CON to ‘110B’. In incremental interface mode, the two inputs associated with
timer T3 (T3IN, T3EUD) are used to interface to an incremental encoder. T3 is clocked
by each transition on one or both of the external input pins to provide 2-fold or 4-fold
resolution of the encoder input.
T3IN
Edge
Select
T3l
Timer T3
Up/
Down
T3R
T3UD
T3OTL
0
To auxiliary
Timers
Interrupt
Request
(T3IR)
MUX
Phase
Detect
T3EUD
XOR
1
T3UDE
MCB04000c
T3IN = P5.3
T3EUD = P5.2
Figure 10-6 Block Diagram of Core Timer T3 in Incremental Interface Mode
Bitfield T3I in control register T3CON selects the triggering transitions (see Table 10-6).
In this mode, the sequence of the transitions of the two input signals is evaluated and
generates count pulses as well as the direction signal. T3 is modified automatically
according to the speed and the direction of the incremental encoder and, therefore, its
contents therefore always represent the encoder’s current position.
Table 10-6
GPT1 Core Timer T3 (Incremental Interface Mode) Input Edge Selection
T3I
Triggering Edge for Counter Increment/Decrement
000
None. Counter T3 stops.
001
Any transition (rising or falling edge) on T3IN.
010
Any transition (rising or falling edge) on T3EUD.
011
Any transition (rising or falling edge) on any T3 input (T3IN or T3EUD).
1XX
Reserved. Do not use this combination.
User’s Manual
10-9
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
The incremental encoder can be connected directly to the C164CM without external
interface logic. In a standard system, however, comparators will be employed to convert
the encoder’s differential outputs (such as A, A) to digital signals (such as A). This greatly
increases noise immunity.
Note: The third encoder output Top0, which indicates the mechanical zero position, may
be connected to an external interrupt input and trigger a reset of timer T3 (for
example via PEC transfer from ZEROS).
Signal
Conditioning
Encoder
Controller
A
A
A
B
B
B
T0
T0
T0
T3Input
T3Input
Interrupt
MCS04372
Figure 10-7 Connection of the Encoder to the C164CM
For incremental interface operation, the following conditions must be met:
• Bitfield T3M must be ‘110B’.
• Both pins T3IN and T3EUD must be configured as input. e.g. the respective direction
control bits must be ‘0’.
• Bit T3UDE must be ‘1’ to enable automatic direction control.
The maximum input frequency allowed in incremental interface mode is fCPU/16. To
ensure that a transition of any input signal is recognized correctly, its level should be held
high or low for at least 8 fCPU cycles before it changes. As in Incremental Interface Mode
two input signals with a 90° phase shift are evaluated, their maximum input frequency
can be fCPU/32.
In Incremental Interface Mode, the count direction is automatically derived from the
sequence in which the input signals change, which corresponds to the rotation direction
of the connected sensor. Table 10-7 summarizes the possible combinations.
Table 10-7
GPT1 Core Timer T3 (Incremental Interface Mode) Count Direction
Level on respective
other input
Rising
Falling
Rising
Falling
High
Down
Up
Up
Down
Low
Up
Down
Down
Up
User’s Manual
T3IN Input
10-10
T3EUD Input
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Figure 10-8 and Figure 10-9 give examples of T3’s operation, visualizing count signal
generation, and direction control. They also show how input jitter is compensated, which
might occur if the sensor rests near to one of its switching points.
Forward
Jitter
Backward
Jitter
Forward
T3IN
T3EUD
Contents
of T3
Up
Down
Up
Note: This example shows the timer behaviour assuming that T3 counts upon any
transition on input, i.e. T3I = '011 B'.
MCT04373
Figure 10-8 Evaluation of the Incremental Encoder Signals
Forward
Jitter
Backward
Jitter
Forward
T3IN
T3EUD
Contents
of T3
Up
Down
Up
Note: This example shows the timer behaviour assuming that T3 counts upon any
transition on input T3IN, i.e. T3I = '001 B'.
MCT04374
Figure 10-9 Evaluation of the Incremental Encoder Signals
Note: Timer T3 operating in incremental interface mode automatically provides
information about the sensor’s current position. Dynamic information (speed,
acceleration, deceleration) may be obtained by measuring the incoming signal
periods.
User’s Manual
10-11
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
10.1.2
GPT1 Auxiliary Timers T2 and T4
Auxiliary timers T2 and T4 have exactly the same functionality. They can be configured
for timer, gated timer, counter, or incremental interface mode with the same options for
the timer frequencies and the count signal as the core timer T3. In addition to these 4
counting modes, the auxiliary timers can be concatenated with the core timer, or they
may be used as reload or capture registers in conjunction with the core timer.
The individual configurations for timers T2 and T4 are determined by their bitaddressable
control registers T2CON and T4CON, which are organized identically. Note that
functions present in all 3 timers of block GPT1 are controlled in the same bit positions
and in the same manner in each of the specific control registers.
Note: The auxiliary timers have no output toggle latch and no alternate output function.
T2CON
Timer 2 Control Register
SFR (FF40H/A0H)
15
14
13
12
11
10
9
-
-
-
-
-
-
-
-
-
-
-
-
-
-
T4CON
Timer 4 Control Register
7
T2
T2
UDE UD
rw
rw
6
5
4
14
13
12
11
10
9
-
-
-
-
-
-
-
-
-
-
-
-
-
-
8
7
T4
T4
UDE UD
rw
rw
10-12
3
2
1
T2R
T2M
T2I
rw
rw
rw
SFR (FF44H/A2H)
15
User’s Manual
8
Reset Value: 0000H
6
0
Reset Value: 0000H
5
4
3
2
1
T4R
T4M
T4I
rw
rw
rw
0
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Bit
Function
TxI
Timer x Input Selection
Depends on the Operating Mode, see respective sections.
TxM
Timer x Mode Control (Basic Operating Mode)
000: Timer Mode
001: Counter Mode
010: Gated Timer with Gate active low
011: Gated Timer with Gate active high
100: Reload Mode
101: Capture Mode
110: Incremental Interface Mode
111: Reserved. Do not use this combination.
TxR
Timer x Run Bit
0:
Timer/Counter x stops
1:
Timer/Counter x runs
TxUD
Timer x Up/Down Control1)
TxUDE
Timer x External Up/Down Enable1)
1)
For the effects of bits TxUD and TxUDE refer to Table 10-1 (see T3 section).
Count Direction Control for Auxiliary Timers
The count direction of the auxiliary timers can be controlled in the same way as for the
core timer T3. The description and the table apply accordingly.
Timers T2 and T4 in Timer Mode or Gated Timer Mode
When the auxiliary timers T2 and T4 are programmed to timer mode or gated timer
mode, their operation is the same as described for the core timer T3. The descriptions,
figures, and tables apply accordingly with one exception: There is no output toggle latch
for T2 and T4.
Timers T2 and T4 in Incremental Interface Mode
When the auxiliary timers T2 and T4 are programmed to incremental interface mode,
their operation is the same as described for the core timer T3. The descriptions, figures,
and tables apply accordingly.
User’s Manual
10-13
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Timers T2 and T4 in Counter Mode
Counter mode for the auxiliary timers T2 and T4 is selected by setting bit field TxM in the
respective register TxCON to ‘001B’. In counter mode, timers T2 and T4 can be clocked
either by a transition at the respective external input pin TxIN, or by a transition of timer
T3’s output toggle latch T3OTL.
Edge
Select
TxIN
Auxiliary Timer Tx
Interrupt
Request
(TxIR)
Up/
Dow
n
TxR
Txl
TxU
D
0
MUX
TxEUD
XOR
1
TxUDE
mcb02221.vsd
x = 2.4
Figure 10-10 Block Diagram of an Auxiliary Timer in Counter Mode
The event causing an increment or decrement of a timer can be a positive, a negative,
or both a positive and a negative transition at either the respective input pin or at the
toggle latch T3OTL.
Bit field TxI in the respective control register TxCON selects the triggering transition (see
Table 10-8).
User’s Manual
10-14
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Table 10-8
GPT1 Auxiliary Timer (Counter Mode) Input Edge Selection
T2I/T4I
Triggering Edge for Counter Increment/Decrement
X00
None. Counter Tx is disabled
001
Positive transition (rising edge) on TxIN
010
Negative transition (falling edge) on TxIN
011
Any transition (rising or falling edge) on TxIN
101
Positive transition (rising edge) of output toggle latch T3OTL
110
Negative transition (falling edge) of output toggle latch T3OTL
111
Any transition (rising or falling edge) of output toggle latch T3OTL
Note: Only state transitions of T3OTL caused by the overflows/underflows of T3 will
trigger the counter function of T2/T4. Modifications of T3OTL via software will NOT
trigger the counter function of T2/T4.
For counter operation, pin TxIN must be configured as an input; the respective direction
control bit must be ‘0’. The maximum input frequency allowed in counter mode is fCPU/
16. To ensure that a transition of the count input signal which is applied to TxIN is
recognized correctly, its level should be held for at least 8 fCPU cycles before it changes.
User’s Manual
10-15
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Timer Concatenation
Using the toggle bit T3OTL as a clock source for an auxiliary timer in counter mode
concatenates the core timer T3 with the respective auxiliary timer. This concatenation
forms either a 32-bit or a 33-bit timer/counter, depending on which transition of T3OTL
is selected to clock the auxiliary timer.
• 32-bit Timer/Counter: If both a positive and a negative transition of T3OTL are used
to clock the auxiliary timer, this timer is clocked on every overflow/underflow of the
core timer T3. Thus, the two timers form a 32-bit timer.
• 33-bit Timer/Counter: If either a positive or a negative transition of T3OTL is selected
to clock the auxiliary timer, this timer is clocked on every second overflow/underflow
of the core timer T3. This configuration forms a 33-bit timer (16-bit core timer + T3OTL
+ 16-bit auxiliary timer).
The count directions of the two concatenated timers are not required to be the same.
This offers a wide variety of different configurations.
T3 can operate in timer, gated timer or counter mode in this case.
Tyl
fCPU
2n : 1
Core Timer Ty
TyR
*)
TyOTL
Up/Down
Interrupt
Request
(TyIR)
Edge
Select
Auxiliary Timer Tx
Interrupt
Request
(TxIR)
TxR
Txl
*) Note: Line only affected by over/underflows of T3, but NOT by software modifications of T3OTL.
MCB02034b
x = 2.4, y = 3
n = 3 … 10
Figure 10-11 Concatenation of Core Timer T3 and an Auxiliary Timer
User’s Manual
10-16
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Auxiliary Timer in Reload Mode
Reload mode for the auxiliary timers T2 and T4 is selected by setting bit field TxM in the
respective register TxCON to ‘100B’. In reload mode, the core timer T3 is reloaded with
the contents of an auxiliary timer register, triggered by one of two different signals. The
trigger signal is selected the same way as the clock source for counter mode (see
Table 10-8), i.e. a transition of the auxiliary timer’s input or the output toggle latch T3OTL
may trigger the reload.
Note: When programmed for reload mode, the respective auxiliary timer (T2 or T4) stops
independently of its run flag T2R or T4R.
Source/Edge
Select
Reload Register Tx
Interrupt
Request
(TxIR)
TxIN
TxI
*)
Input
Clock
Interrupt
Request
(T3IR)
Core Timer T3
Up/Down
T3OTL
x = 2, 4
*) Note: Line only affected by over/underflows of T3, but NOT by software modifications of T3OTL.
MCB02035b
Figure 10-12 GPT1 Auxiliary Timer in Reload Mode
Upon a trigger signal, T3 is loaded with the contents of the respective timer register (T2
or T4) and the interrupt request flag (T2IR or T4IR) is set.
Note: When a T3OTL transition is selected for the trigger signal, the interrupt request
flag T3IR will also be set upon a trigger, indicating T3’s overflow or underflow.
Modifications of T3OTL via software will NOT trigger the counter function of T2/T4.
User’s Manual
10-17
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
The reload mode triggered by T3OTL can be used in a number of different
configurations. The following functions can be performed, depending on the selected
active transition:
• If both a positive and a negative transition of T3OTL are selected to trigger a reload,
the core timer will be reloaded with the contents of the auxiliary timer each time it
overflows or underflows. This is the standard reload mode (reload on overflow/
underflow).
• If either a positive or a negative transition of T3OTL is selected to trigger a reload, the
core timer will be reloaded with the contents of the auxiliary timer on every second
overflow or underflow.
• Using this “single-transition” mode for both auxiliary timers allows very flexible Pulse
Width Modulation (PWM). One of the auxiliary timers is programmed to reload the
core timer on a positive transition of T3OTL, the other is programmed for a reload on
a negative transition of T3OTL. With this combination, the core timer is alternately
reloaded from the two auxiliary timers.
Note: Although possible, selecting the same reload trigger event for both auxiliary timers
should be avoided. In such a case, both reload registers would try to load the core
timer at the same time. If this combination is selected, T2 is disregarded and the
contents of T4 is reloaded.
User’s Manual
10-18
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
Auxiliary Timer in Capture Mode
Capture mode for the auxiliary timers T2 and T4 is selected by setting bit field TxM in the
respective register TxCON to ‘101B’. In capture mode, the contents of the core timer are
latched into an auxiliary timer register in response to a signal transition at the respective
auxiliary timer’s external input pin TxIN. The capture trigger signal can be a positive, a
negative, or both a positive and a negative transition.
The two least significant bits of bit field TxI are used to select the active transition (see
Table 10-8), while the most significant bit TxI.2 is irrelevant for capture mode. It is
recommended to keep this bit cleared (TxI.2 = ‘0’).
Note: When programmed for capture mode, the respective auxiliary timer (T2 or T4)
stops independently of its run flag T2R or T4R.
Edge
Select
Capture Register Tx
Interrupt
Request
(TxIR)
TxIN
Input
Clock
TxI
Interrupt
Request
(T3IR)
Core Timer T3
Up/Down
T3OTL
x = 2, 4
MCB02038b
Figure 10-13 GPT1 Auxiliary Timer in Capture Mode
Upon a trigger (selected transition) at the corresponding input pin TxIN the contents of
the core timer are loaded into the auxiliary timer register and the associated interrupt
request flag TxIR will be set.
Note: To ensure correct edge detection, the direction control bits for T2IN and T4IN must
be set to ‘0’ and the level of the capture trigger signal should be held high or low
for at least 8 fCPU cycles before it changes.
User’s Manual
10-19
V1.0, 2002-02
C164CM/C164SM
Derivatives
General Purpose Timer Unit
10.1.3
Interrupt Control for GPT1 Timers
When a timer overflows from FFFFH to 0000H (counting up), or when it underflows from
0000H to FFFFH (counting down), its interrupt request flag (T2IR, T3IR or T4IR) in
register TxIC will be set. This will cause an interrupt to the respective timer interrupt
vector (T2INT, T3INT or T4INT) or will trigger a PEC service, if the respective interrupt
enable bit (T2IE, T3IE or T4IE in register TxIC) is set. There is an interrupt control
register for each of the three timers.
T2IC
Timer 2 Intr. Ctrl. Reg.
15
14
13
12
SFR (FF60H/B0H)
11
10
9
8
-
-
-
14
13
-
-
12
-
-
-
-
-
11
10
14
13
-
-
12
9
8
-
-
-
-
-
-
4
7
rwh
11
10
9
8
7
T4IR T4IE
-
-
-
-
rwh
rw
1
0
rw
rw
Reset Value: - - 00H
5
4
3
2
1
0
ILVL
GLVL
rw
rw
rw
6
2
GLVL
rw
6
3
ILVL
SFR (FF64H/B2H)
-
rwh
T3IR T3IE
T4IC
Timer 4 Intr. Ctrl. Reg.
15
5
SFR (FF62H/B1H)
-
6
T2IR T2IE
T3IC
Timer 3 Intr. Ctrl. Reg.
15
7
Reset Value: - - 00H
Reset Value: - - 00H
5
4
3
2
1
0
ILVL
GLVL
rw
rw
Note: Please refer to the general Interrupt Control Register description for an
explanation of the control fields.
User’s Manual
10-20
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
11
Asynchronous/Synchronous Serial Interface
The Asynchronous/Synchronous Serial Interface ASC0 provides serial communication
between the C164CM and other microcontrollers, microprocessors, or external
peripherals.
The ASC0 supports both full-duplex asynchronous communication and half-duplex
synchronous communication (for baud rate ranges see formulas and tables in
Section 11.4). In synchronous mode, data are transmitted or received synchronous to a
shift clock generated by the C164CM. In asynchronous mode, selection of 8- or 9-bit data
transfer, parity generation, and the number of stop bits can be made. Parity, framing, and
overrun error detection are provided to increase the reliability of data transfers.
Transmission and reception of data are double-buffered. For multiprocessor
communication, a mechanism is provided to distinguish address bytes from data bytes.
Testing is supported by a loop-back option. A 13-bit baud rate generator provides the
ASC0 with a separate serial clock signal.
Ports & Direction Control
Alternate Functions
DP0H
P0H
E
Data Registers
S0BG
Control Registers
Interrupt Control
S0CON
S0TIC
S0TBUF
S0RIC
S0RBUF
S0EIC
RXD0/P0H.4
TXD0/P0H.3
DP0H
S0BG
S0TBUF
S0TIC
S0TBIC
S0TBIC
Port 0 Direction Control Register
ASC0 Baud Rate Generator/Reload Reg.
ASC0 Transmit Buffer Register
ASC0 Transmit Interrupt Control Register
ASC0 Transmit Buffer Interrupt Ctrl. Reg.
E
P0H
Port 0 Data Register High
S0CON ASC0 Control Register
S0RBUF ASC0 Receive Buffer Register (read
only)
S0RIC
ASC0 Receive Interrupt Control
Register
S0EIC
ASC0 Error Interrupt Control Register
MCA05133
Figure 11-1 SFRs and Port Pins Associated with ASC0
User’s Manual
11-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
The operating mode of the serial channel ASC0 is controlled by its bit-addressable
control register S0CON. This register contains control bits for mode and error check
selection, as well as status flags for error identification.
S0CON
ASC0 Control Register
15
S0R
rw
14
13
10
9
S0 S0 S0
LB BRS ODD
-
S0
OE
S0
FE
S0 S0 S0 S0 S0 S0
PE OEN FEN PEN REN STP
rw
-
rwh
rwh
rwh
rw
8
7
rw
6
Reset Value: 0000H
11
rw
12
SFR (FFB0H/D8H)
rw
5
rw
Bit
Function
S0M
ASC0 Mode Control
000: 8-bit data
001: 8-bit data
010: Reserved. Do not use this combination!
011: 7-bit data + parity
100: 9-bit data
101: 8-bit data + wake up bit
110: Reserved. Do not use this combination!
111: 8-bit data + parity
4
rwh
3
rw
2
1
0
S0M
rw
synchronous operation
asynchronous operation
asynchronous operation
asynchronous operation
asynchronous operation
asynchronous operation
S0STP
Number of Stop Bits Selection
0:
One stop bit
1:
Two stop bits
S0REN
Receiver Enable Bit
0:
Receiver disabled
1:
Receiver enabled
(Reset by hardware after reception of byte in synchronous mode)
S0PEN
Parity Check Enable Bit
0:
Ignore parity
1:
Check parity
asynchronous operation
S0FEN
Framing Check Enable Bit
0:
Ignore framing errors
1:
Check framing errors
asynchronous operation
S0OEN
Overrun Check Enable Bit
0:
Ignore overrun errors
1:
Check overrun errors
User’s Manual
11-2
asynchronous operation
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
Bit
Function
S0PE
Parity Error Flag
Set by hardware on a parity error (S0PEN = ‘1’). Must be reset by
software.
S0FE
Framing Error Flag
Set by hardware on a framing error (S0FEN = ‘1’). Must be reset by
software.
S0OE
Overrun Error Flag
Set by hardware on an overrun error (S0OEN = ‘1’). Must be reset by
software.
S0ODD
Parity Selection Bit
0:
Even parity (parity bit set on odd number of ‘1’s in data)
1:
Odd parity (parity bit set on even number of ‘1’s in data)
S0BRS
Baudrate Selection Bit
0:
Divide clock by reload-value + constant (depending on mode)
1:
Additionally reduce serial clock to 2/3
S0LB
Loopback Mode Enable Bit
0:
Standard transmit/receive mode
1:
Loopback mode enabled
S0R
Baudrate Generator Run Bit
0:
Baudrate generator disabled (ASC0 inactive)
1:
Baudrate generator enabled
A transmission is started by writing to the Transmit Buffer register S0TBUF (via an
instruction or a PEC data transfer). The number of data bits to be actually transmitted is
determined by the operating mode selected; that is, bits written to positions 9 through 15
of register S0TBUF are always insignificant. After a transmission has been completed,
the transmit buffer register is cleared to 0000H.
Data transmission is double-buffered so that a new character may be written to the
transmit buffer register before the transmission of the previous character is complete.
This allows the transmission of characters back-to-back without gaps.
Data reception is enabled by the Receiver Enable Bit S0REN. After reception of a
character has been completed, the received data and if provided by the selected
operating mode the received parity bit can be read from the (read-only) Receive Buffer
register S0RBUF. Bits in the upper half of S0RBUF not valid in the selected operating
mode will be read as zeros.
Data reception is double-buffered so that reception of a second character may begin
before the previously received character has been read out of the receive buffer register.
In all modes, receive buffer overrun error detection can be selected through bit S0OEN.
User’s Manual
11-3
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
When enabled, the overrun error status flag S0OE and the error interrupt request flag
S0EIR will be set if the receive buffer register has not been read by the time reception of
a second character is complete. The previously received character in the receive buffer
is overwritten.
The Loop-Back option (selected by bit S0LB) allows the data currently being
transmitted to be received simultaneously in the receive buffer. This may be used to test
serial communication routines at an early stage without having to provide an external
network. In loop-back mode, the alternate input/output functions of the Port pins are not
necessary.
Note: Serial data transmission or reception is only possible when the Baud Rate
Generator Run Bit S0R is set to ‘1’. Otherwise, the serial interface is idle.
To avoid unpredictable behavior of the serial interface do not program the mode
control field S0M in register S0CON to one of the reserved combinations.
User’s Manual
11-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
11.1
Asynchronous Operation
Asynchronous mode supports full-duplex communication in which both transmitter and
receiver use the same data frame format and the same baud rate. Data is transmitted on
pin TXD0 and received on pin RXD0. These signals are alternate port functions.
Reload Register
CPU
Clock
÷2
÷ 16
Baud Rate Timer
S0R
S0M S0STP
S0REN
S0FEN
S0PEN
S0OEN
S0LB
RXD0
S0PE
S0FE S0OE
Clock
S0RIR
Receive Int.
Request
Serial Port Control
S0TIR
Transmit Int.
Request
Shift Clock
S0EIR
Error Int.
Request
0
MUX
Sampling
Receive Shift
Register
Transmit Shift
Register
TXD0
1
Transmit Buffer Reg.
S0TBUF
Receive Buffer Reg.
S0RBUF
Internal Bus
MCB02219
Figure 11-2 Asynchronous Mode of Serial Channel ASC0
Asynchronous Data Frames
8-bit data frames consist of either 8 data bits D7 … D0 (S0M = ‘001B’), or 7 data bits D6
… D0 plus an automatically generated parity bit (S0M = ‘011B’). Parity may be odd or
even, depending on bit S0ODD in register S0CON. An even parity bit will be set, if the
modulo-2-sum of the 7 data bits is ‘1’. An odd parity bit will be cleared in this case. Parity
checking is enabled via bit S0PEN (always OFF in 8-bit data mode). The parity error flag
User’s Manual
11-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
S0PE will be set along with the error interrupt request flag, if a wrong parity bit is
received. The parity bit itself will be stored in bit S0RBUF.7.
Start
D0
Bit (LSB)
D1
D2
D3
D4
D5
D6
(1st)
D7 /
Stop
Parity
Bit
2nd
Stop
Bit
MCT04377
Figure 11-3 Asynchronous 8-bit Data Frames
9-bit data frames consist of either 9 data bits D8 … D0 (S0M = ‘100B’), 8 data bits
D7 … D0 plus an automatically generated parity bit (S0M = ‘111B’), or 8 data bits
D7 … D0 plus a wake-up bit (S0M = ‘101B’). Parity may be odd or even, depending on
bit S0ODD in register S0CON. An even parity bit will be set, if the modulo-2-sum of the
8 data bits is ‘1’. An odd parity bit will be cleared in this case. Parity checking is enabled
via bit S0PEN (always OFF in 9-bit data and wake-up modes). The parity error flag S0PE
will be set along with the error interrupt request flag if a wrong parity bit is received. The
parity bit itself will be stored in bit S0RBUF.8.
In wake-up mode, received frames are transferred to the receive buffer register only if
the 9th bit (the wake-up bit) is ‘1’. If this bit is ‘0’, no receive interrupt request will be
activated and no data will be transferred.
This feature may be used to control communication in a multi-processor system: 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 additional 9th bit is a ‘1’ for an address byte and a ‘0’ for a data
byte, so that no slave will be interrupted by a data ‘byte’. An address ‘byte’ will interrupt
all slaves (operating in 8-bit data + wake-up bit modes), so each slave can examine the
8 LSBs of the received character (the address). The addressed slave will switch to 9-bit
data mode (for example, by clearing bit S0M.0), which enables it to also receive the data
bytes that will be coming (having the wake-up bit cleared). The slaves not being
addressed remain in 8-bit data + wake-up bit modes, ignoring the following data bytes.
Start
D0
Bit (LSB)
D1
D2
D3
D4
D5
D6
D7
9th
Bit
(1st)
Stop
Bit
2nd
Stop
Bit
Data Bit D8
Parity
Wake-up Bit
MCT04378
Figure 11-4 Asynchronous 9-bit Data Frames
User’s Manual
11-6
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
Asynchronous transmission begins at the next overflow of the divide-by-16 counter
(see Figure 11-4), provided that S0R is set and data has been loaded into S0TBUF. The
transmitted data frame consists of three basic elements:
• the start bit
• the data field (8 or 9 bits, LSB first, including a parity bit, if selected)
• the delimiter (1 or 2 stop bits)
Data transmission is double-buffered. When the transmitter is idle, the transmit data
loaded into S0TBUF is immediately moved to the transmit shift register thus freeing
S0TBUF for the next data to be sent. This is indicated by the transmit buffer interrupt
request flag S0TBIR being set. S0TBUF may now be loaded with the next data, while
transmission of the previous one is still going on.
The transmit interrupt request flag S0TIR will be set before the last bit of a frame is
transmitted, that is, before the first or the second stop bit is shifted out of the transmit
shift register.
The transmitter output pin TXD0 must be configured for alternate data output, that is, the
respective port output latch and the direction latch must be ‘1’.
Asynchronous reception is initiated by a falling edge (1-to-0 transition) on pin RXD0,
provided that bits S0R and S0REN are set. The receive data input pin RXD0 is sampled
at 16 times the rate of the selected baud rate. A majority decision of the 7th, 8th, and 9th
sample determines the effective bit value. This avoids erroneous results that may be
caused by noise.
If the detected value is not a ‘0’ when the start bit is sampled, the receive circuit is reset
and waits for the next 1-to-0 transition at pin RXD0. If the start bit proves valid, the
receive circuit continues sampling and shifts the incoming data frame into the receive
shift register.
When the last stop bit has been received, the content of the receive shift register is
transferred to the receive data buffer register S0RBUF. Simultaneously, the receive
interrupt request flag S0RIR is set after the 9th sample in the last stop bit time slot (as
programmed), whether or not valid stop bits have been received. The receive circuit then
waits for the next start bit (1-to-0 transition) at the receive data input pin.
The receiver input pin RXD0 must be configured for input, that is, the respective direction
latch must be ‘0’.
Asynchronous reception is stopped by clearing bit S0REN. A frame currently being
received is completed including the generation of the receive interrupt request and an
error interrupt request, if appropriate. Start bits following this frame will not be
recognized.
Note: In wake-up mode, received frames are transferred to the receive buffer register
only if the 9th bit (the wake-up bit) is ‘1’. If this bit is ‘0’, no receive interrupt request
will be activated and no data will be transferred.
User’s Manual
11-7
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
11.2
Synchronous Operation
Synchronous mode supports half-duplex communication, primarily for simple IO
expansion via shift registers. Data is transmitted and received via pin RXD0, while pin
TXD0 outputs the shift clock. These signals are alternate port functions. Synchronous
mode is selected with S0M = ‘000B’.
8 data bits are transmitted or received synchronous to a shift clock generated by the
internal baud rate generator. The shift clock is active only as long as data bits are
transmitted or received.
Reload Register
CPU
Clock
÷2
÷4
Baud Rate Timer
S0R
S0M = 000B
Clock
S0RIR
Receive Int.
Request
Serial Port Control
S0TIR
Transmit Int.
Request
S0EIR
Error Int.
Request
S0REN
S0OEN
TXD0
S0LB
S0OE
Shift Clock
Receive
0
MUX
RXD0
Receive Shift
Register
Transmit Shift
Register
Receive Buffer Reg.
S0RBUF
Transmit Buffer Reg.
S0TBUF
1
Transmit
Internal Bus
MCB02220
Figure 11-5 Synchronous Mode of Serial Channel ASC0
User’s Manual
11-8
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
Synchronous transmission begins within 4 state times after data has been loaded into
S0TBUF, provided that S0R is set and S0REN = ‘0’ (half-duplex, no reception). Data
transmission is double-buffered. When the transmitter is idle, the transmit data loaded
into S0TBUF is immediately moved to the transmit shift register, thus, freeing S0TBUF
for the next data to be sent. This is indicated by the transmit buffer interrupt request flag
S0TBIR being set. S0TBUF may now be loaded with the next data, while transmission
of the previous data is still going on. The data bits are transmitted synchronous with the
shift clock. After the bit time for the 8th data bit, both pins TXD0 and RXD0 will go high,
the transmit interrupt request flag S0TIR is set, and serial data transmission stops.
Pin TXD0 must be configured for alternate data output, that is the respective port output
latch and the direction latch must be ‘1’, in order to provide the shift clock. Pin RXD0 must
also be configured for output (output/direction latch = ‘1’) during transmission.
Synchronous reception is initiated by setting bit S0REN = ‘1’. If bit S0R = ‘1’, the data
applied at pin RXD0 are clocked into the receive shift register synchronous to the clock
output at pin TXD0. After the 8th bit has been shifted in, the content of the receive shift
register is transferred to the receive data buffer S0RBUF, the receive interrupt request
flag S0RIR is set, the receiver enable bit S0REN is reset, and serial data reception stops.
Pin TXD0 must be configured for alternate data output, that is, the respective port output
latch and the direction latch must be ‘1’, in order to provide the shift clock. Pin RXD0 must
be configured as alternate data input, that is, the respective direction latch must be ‘0’.
Synchronous reception is stopped by clearing bit S0REN. A byte currently being
received is completed including generation of the receive interrupt request and an error
interrupt request, if appropriate. Writing to the transmit buffer register while a reception
is in progress has no effect on reception and will not start a transmission.
If a previously received byte has not been read out of the receive buffer register at the
time that reception of the next byte is complete, both the error interrupt request flag
S0EIR and the overrun error status flag S0OE will be set, provided the overrun check
has been enabled by bit S0OEN.
User’s Manual
11-9
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
11.3
Hardware Error Detection Capabilities
To enhance reliability of serial data exchange, the serial channel ASC0 provides an error
interrupt request flag, which indicates the presence of an error, and three (selectable)
error status flags in register S0CON, which indicate which error has been detected
during reception. Upon completion of a reception, the error interrupt request flag S0EIR
will be set simultaneously with the receive interrupt request flag S0RIR, if one or more of
the following conditions are met:
• If the framing error detection enable bit S0FEN is set and any expected stop bit is not
high, the framing error flag S0FE is set, indicating that the error interrupt request is
due to a framing error (Asynchronous mode only).
• If the parity error detection enable bit S0PEN is set in the modes in which a parity bit
is received, and the parity check on the received data bits proves false, the parity error
flag S0PE is set, indicating that the error interrupt request is due to a parity error
(Asynchronous mode only).
• If the overrun error detection enable bit S0OEN is set and the last character received
was not read out of the receive buffer by software or by PEC transfer at the time the
reception of a new frame is complete, the overrun error flag S0OE is set, indicating
that the error interrupt request is due to an overrun error (Asynchronous and
Synchronous modes).
User’s Manual
11-10
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
11.4
ASC0 Baud Rate Generation
The serial channel ASC0 has its own dedicated 13-bit baud rate generator with 13-bit
reload capability, allowing baud rate generation independent of the GPT timers.
The baud rate generator is clocked with the CPU clock divided by 2 (fCPU/2). The timer
counts downwards and can be started or stopped through the Baud Rate Generator Run
Bit S0R in register S0CON. Each underflow of the timer provides one clock pulse to the
serial channel. The timer is reloaded with the value stored in its 13-bit reload register
each time it underflows. The resulting clock is again divided according to the operating
mode and controlled by the Baudrate Selection Bit S0BRS. If S0BRS = ‘1’, the clock
signal is additionally divided to 2/3rd of its frequency (see formulas and table). So the
baud rate of ASC0 is determined by the CPU clock, the reload value, the value of S0BRS
and the operating mode (asynchronous or synchronous).
Register S0BG is the dual-function Baud Rate Generator/Reload register. Reading
S0BG returns the content of the timer (bits 15 … 13 return zero), while writing to S0BG
always updates the reload register (bits 15 … 13 are insignificant).
Each time S0BG is written to, an auto-reload of the timer with the content of the reload
register is performed. However, if S0R = ‘0’ at the time the write operation to S0BG is
performed, the timer will not be reloaded until the first instruction cycle after S0R = ‘1’.
Asynchronous Mode Baud Rates
For asynchronous operation, the baud rate generator provides a clock with 16 times the
rate of the established baud rate. Every received bit is sampled at the 7th, 8th and 9th
cycle of this clock. The baud rate for asynchronous operation of serial channel ASC0 and
the required reload value for a given baudrate can be determined by the following
formulas:
BAsync =
fCPU
16 × (2 + <S0BRS>) × (<S0BRL> + 1)
S0BRL = (
fCPU
16 × (2 + <S0BRS>) × BAsync
)-1
<S0BRL> represents the contents of the reload register taken as unsigned 13-bit integer,
<S0BRS> represents the value of bit S0BRS (either ‘0’ or ‘1’), taken as integer.
The tables below list various commonly used baud rates and the required reload values
and deviation errors compared to the intended baud rates for a number of CPU
frequencies.
Note: The deviation errors given in the tables below are rounded. Using a baudrate
crystal (such as 18.432 MHz) will provide correct baud rates without deviation
errors.
User’s Manual
11-11
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
Table 11-1
ASC0 Asynchronous Baudrate Generation for fCPU = 16 MHz
Baud Rate
S0BRS = ‘0’
S0BRS = ‘1’
Deviation Error
Reload Value
Deviation Error
Reload Value
500
kbit/s
±0.0%
0000H
–
–
19.2
kbit/s
+0.2%/ -3.5%
0019H/001AH
+2.1%/ -3.5%
0010H/0011H
9600
bit/s
+0.2%/ -1.7%
0033H/0034H
+2.1%/ -0.8%
0021H/0022H
4800
bit/s
+0.2%/ -0.8%
0067H/0068H
+0.6%/ -0.8%
0044H/0045H
2400
bit/s
+0.2%/ -0.3%
00CFH/00D0H
+0.6%/ -0.1%
0089H/008AH
1200
bit/s
+0.4%/ -0.1%
019FH/01A0H
+0.3%/ -0.1%
0114H/0115H
600
bit/s
+0.0%/ -0.1%
0340H/0341H
+0.1%/ -0.1%
022AH/022BH
61
bit/s
+0.1%
1FFFH
+0.0%/ -0.0%
115BH/115CH
40
bit/s
–
–
+1.7%
1FFFH
Table 11-2
ASC0 Asynchronous Baudrate Generation for fCPU = 20 MHz
Baud Rate
S0BRS = ‘0’
S0BRS = ‘1’
Deviation Error
Reload Value
Deviation Error
Reload Value
625
kbit/s
±0.0%
0000H
–
–
19.2
kbit/s
+1.7%/ -1.4%
001FH/0020H
+3.3%/ -1.4%
0014H/0015H
9600
bit/s
+0.2%/ -1.4%
0040H/0041H
+1.0%/ -1.4%
002AH/002BH
4800
bit/s
+0.2%/ -0.6%
0081H/0082H
+1.0%/ -0.2%
0055H/0056H
2400
bit/s
+0.2%/ -0.2%
0103H/0104H
+0.4%/ -0.2%
00ACH/00ADH
1200
bit/s
+0.2%/ -0.4%
0207H/0208H
+0.1%/ -0.2%
015AH/015BH
600
bit/s
+0.1%/ -0.0%
0410H/0411H
+0.1%/ -0.1%
02B5H/02B6H
75
bit/s
+1.7%
1FFFH
+0.0%/ -0.0%
15B2H/15B3H
50
bit/s
–
–
+1.7%
1FFFH
User’s Manual
11-12
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
Table 11-3
ASC0 Asynchronous Baudrate Generation for fCPU = 25 MHz
Baud Rate
S0BRS = ‘0’
S0BRS = ‘1’
Deviation Error
Reload Value
Deviation Error
Reload Value
781
kbit/s
+0.2%
0000H
–
–
19.2
kbit/s
+1.7%/ -0.8%
0027H/0028H
+0.5%/ -3.1%
001AH/001BH
9600
bit/s
+0.5%/ -0.8%
0050H/0051H
+0.5%/ -1.4%
0035H/0036H
4800
bit/s
+0.5%/ -0.2%
00A1H/00A2H
+0.5%/ -0.5%
006BH/006CH
2400
bit/s
+0.2%/ -0.2%
0145H/0146H
+0.0%/ -0.5%
00D8H/00D9H
1200
bit/s
+0.0%/ -0.2%
028AH/028BH
+0.0%/ -0.2%
01B1H/01B2H
600
bit/s
+0.0%/ -0.1%
0515H/0516H
+0.0%/ -0.1%
0363H/0364H
95
bit/s
+0.4%
1FFFH
+0.0%/ -0.0%
1569H/156AH
63
bit/s
–
–
+1.0%
1FFFH
Table 11-4
ASC0 Asynchronous Baudrate Generation for fCPU = 33 MHz
Baud Rate
S0BRS = ‘0’
S0BRS = ‘1’
Deviation Error
Reload Value
Deviation Error
Reload Value
1.031 Mbit/s
±0.0%
0000H
–
–
19.2
kbit/s
+1.3%/ -0.5%
0034H/0035H
+2.3%/ -0.5%
0022H/0023H
9600
bit/s
+0.4%/ -0.5%
006AH/006BH
+0.9%/ -0.5%
0046H/0047H
4800
bit/s
+0.4%/ -0.1%
00D5H/00D6H
+0.2%/ -0.5%
008EH/008FH
2400
bit/s
+0.2%/ -0.1%
01ACH/01ADH +0.2%/ -0.2%
011DH/011EH
1200
bit/s
+0.0%/ -0.1%
035AH/035BH
+0.2%/ -0.0%
023BH/023CH
600
bit/s
+0.0%/ -0.0%
06B5H/06B6H
+0.1%/ -0.0%
0478H/0479H
125
bit/s
+7.1%
1FFFH
±0.0%
157CH
84
bit/s
–
–
-0.9%
1FFFH
User’s Manual
11-13
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
Synchronous Mode Baud Rates
For synchronous operation, the baud rate generator provides a clock with 4 times the
rate of the established baud rate. The baud rate for synchronous operation of serial
channel ASC0 can be determined by the following formula:
S0BRL = (
BSync =
fCPU
)-1
4 × (2 + <S0BRS>) × BSync
fCPU
4 × (2 + <S0BRS>) × (<S0BRL> + 1)
<S0BRL> represents the contents of the reload register, taken as unsigned 13-bit integers,
<S0BRS> represents the value of bit S0BRS (either ‘0’ or ‘1’), taken as integer.
Table 11-5 gives the limit baudrates depending on the CPU clock frequency and bit
S0BRS.
Table 11-5
ASC0 Synchronous Baudrate Generation
S0BRS = ‘0’
CPU clock
S0BRS = ‘1’
fCPU
Min. Baudrate
Max. Baudrate
Min. Baudrate
Max. Baudrate
16 MHz
244 bit/s
2.000 Mbit/s
162 bit/s
1.333 Mbit/s
20 MHz
305 bit/s
2.500 Mbit/s
203 bit/s
1.666 Mbit/s
25 MHz
381 bit/s
3.125 Mbit/s
254 bit/s
2.083 Mbit/s
33 MHz
504 bit/s
4.125 Mbit/s
336 bit/s
2.750 Mbit/s
User’s Manual
11-14
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
11.5
ASC0 Interrupt Control
Four bit-addressable interrupt control registers are provided for serial channel ASC0.
Register S0TIC controls the transmit interrupt, S0TBIC controls the transmit buffer
interrupt, S0RIC controls the receive interrupt, and S0EIC controls the error interrupt of
serial channel ASC0. Each interrupt source also has its own dedicated interrupt vector.
S0TINT is the transmit interrupt vector, S0TBINT is the transmit buffer interrupt vector,
S0RINT is the receive interrupt vector, and S0EINT is the error interrupt vector.
The cause of an error interrupt request (framing, parity, overrun error) can be identified
by the error status flags in control register S0CON.
Note: In contrast to the error interrupt request flag S0EIR, the error status flags S0FE/
S0PE/S0OE are not reset automatically upon entry into the error interrupt service
routine, but must be cleared by software.
S0TIC
ASC0 Tx Intr. Ctrl. Reg.
15
14
13
12
11
SFR (FF6CH/B6H)
10
9
8
-
-
-
-
-
-
S0TBIC
ASC0 Tx Buf. Intr. Ctrl. Reg.
15
14
13
12
11
10
-
-
-
-
-
14
13
-
12
9
8
-
11
-
-
-
User’s Manual
-
-
5
-
4
S0
TIR
S0
TIE
ILVL
GLVL
rwh
rw
rw
rw
7
6
rwh
10
9
8
-
-
-
3
2
1
0
Reset Value: - - 00H
5
4
3
2
1
0
ILVL
GLVL
rw
rw
rw
SFR (FF6EH/B7H)
-
6
S0 S0
TBIR TBIE
S0RIC
ASC0 Rx Intr. Ctrl. Reg.
15
7
SFR (FF9CH/CEH)
-
Reset Value: - - 00H
Reset Value: - - 00H
7
6
S0
RIR
S0
RIE
ILVL
GLVL
rwh
rw
rw
rw
11-15
5
4
3
2
1
0
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
S0EIC
ASC0 Error Intr. Ctrl. Reg.
15
14
13
12
11
SFR (FF70H/B8H)
10
9
8
-
-
-
-
-
-
-
-
Reset Value: - - 00H
7
6
5
4
3
2
1
0
S0
EIR
S0
EIE
ILVL
GLVL
rwh
rw
rw
rw
Note: Please refer to the general Interrupt Control Register description for an
explanation of the control fields.
Using the ASC0 Interrupts
For normal operation (other than the error interrupt), the ASC0 provides three interrupt
requests to control data exchange via this serial channel:
• S0TBIR is activated when data is moved from S0TBUF to the transmit shift register.
• S0TIR is activated before the last bit of an asynchronous frame is transmitted,
or after the last bit of a synchronous frame has been transmitted.
• S0RIR is activated when the received frame is moved to S0RBUF.
While the task of the receive interrupt handler is quite clear, the transmitter is serviced
by two interrupt handlers. This provides advantages for the servicing software.
For single transfers, it is sufficient to use the transmitter interrupt (S0TIR) which
indicates that the previously loaded data has been transmitted (except for the last bit of
an asynchronous frame).
For multiple back-to-back transfers, it is necessary to load the subsequent piece of
data at last until the last bit of the previous frame has been transmitted. In asynchronous
mode this leaves only one bit-time for the handler to respond to the transmitter interrupt
request. In synchronous mode this makes response impossible.
Using the transmit buffer interrupt (S0TBIR) to reload transmit data provides the time to
transmit a complete frame for the service routine, as S0TBUF may be reloaded while the
previous data is still being transmitted.
User’s Manual
11-16
V1.0, 2002-02
C164CM/C164SM
Derivatives
Asynchronous/Synchronous Serial Interface
S0TIR
Asynchronous Mode
S0RIR
S0TIR
S0TBIR
Idle
S0RIR
S0TIR
S0TBIR
Idle
Synchronous Mode
Stop
Start
Stop
S0RIR
S0TIR
S0TBIR
S0TIR
S0TBIR
Start
S0TBIR
Stop
Idle
Start
S0TBIR
S0TIR
Idle
S0RIR
S0RIR
S0RIR
MCT04379
Figure 11-6 ASC0 Interrupt Generation
As shown in Figure 11-6, S0TBIR is an early trigger for the reload routine, while S0TIR
indicates the completed transmission. Therefore, software using handshake should rely
on S0TIR at the end of a data block to ensure that all data has really been transmitted.
User’s Manual
11-17
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
12
High-Speed Synchronous Serial Interface
The high-speed Synchronous Serial Interface (SSC) provides flexible high-speed serial
communication between the C164CM and other microcontrollers, microprocessors, or
external peripherals.
The SSC supports full-duplex and half-duplex synchronous communication (for baud
rate ranges see formulas and tables in Section 12.5). The serial clock signal can be
generated by the SSC itself (master mode) or can be received from an external master
(slave mode). Data width, shift direction, clock polarity, and phase are programmable.
This allows communication with SPI-compatible devices. Transmission and reception of
data is double-buffered. A 16-bit baud rate generator provides the SSC with a separate
serial clock signal.
Configuration of the high-speed synchronous serial interface is very flexible, so it can be
used with other synchronous serial interfaces (such as the ASC0 in synchronous mode),
it can serve for master/slave or multimaster interconnections, or it can operate
compatibly with the popular SPI interface. Thus, the SSC can be used to communicate
with shift registers (IO expansion), peripherals (EEPROMs etc.) or other controllers
(networking). The SSC supports half-duplex and full-duplex communication. Data is
transmitted or received on pins MTSR/P0H.6 (Master Transmit/Slave Receive) and
MRST/P0H.5 (Master Receive/Slave Transmit). The clock signal is output or input on pin
SCLK/P0H.7. These pins are alternate functions of PORT0 pins.
Ports & Direction Control
Alternate Functions
DP0H
P0H
E
Data Registers
Control Registers
Interrupt Control
SSCCON
SSCTIC
SSCBR
E
SSCTB
E
SSCRIC
SSCRB
E
SSCEIC
SCLK/P0H.7
MTSR/P0H.6
MRST/P0H.5
DP0H
SSCBR
SSCTB
SSCTIC
Port 0 Direction Control Register
SSC Baud Rate Generator/Reload Reg.
SSC Transmit Buffer Register
SSC Transmit Interrupt Control Register
P0H
SSCCON
SSCRB
SSCRIC
SSCEIC
Port 0 Data Register High
SSC Control Register
SSC Receive Buffer Register
SSC Receive Interrupt Control Register
SSC Error Interrupt Control Register
MCA05134
Figure 12-1 SFRs and Port Pins Associated with the SSC
User’s Manual
12-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
CPU
Clock
Baud Rate
Generator
Slave Clock
Master Clock
Clock
Control
SCLK
Shift
Clock
Receive Int. Request
Transmit Int. Request
Error Int.Request
SSC Control Block
Status
Control
MTSR
Pin
Control
16-Bit Shift Register
Transmit Buffer
Register SSCTB
MRST
Receive Buffer
Register SSCRB
Internal Bus
MCB01957
Figure 12-2 Synchronous Serial Channel SSC Block Diagram
The operating mode of the serial channel SSC is controlled by its bit-addressable control
register SSCCON. This register serves two purposes:
• During programming (SSC disabled by SSCEN = ‘0’) it provides access to a set of
control bits,
• During operation (SSC enabled by SSCEN = ‘1’) it provides access to a set of status
flags.
Register SSCCON is shown below in each of the two modes.
SSCCON
SSC Control Reg. (Pr.M.)
15
14
13
SSC SSC
EN
= 0 MS
rw
rw
User’s Manual
-
12
11
SFR (FFB2H/D9H)
10
9
8
7
SSC SSC SSC SSC SSC
AR BEN PEN REN TEN
EN
rw
rw
rw
rw
rw
rw
12-2
6
Reset Value: 0000H
5
4
SSC SSC SSC
PO PH HB
rw
rw
rw
3
2
1
0
SSCBM
rw
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
Bit
Function (Programming Mode, SSCEN = ‘0’)
SSCBM
SSC Data Width Selection
0:
Reserved. Do not use this combination
1…15: Transfer Data Width is 2 … 16 bit (<SSCBM> + 1)
SSCHB
SSC Heading Control Bit
0:
Transmit/Receive LSB First
1:
Transmit/Receive MSB First
SSCPH
SSC Clock Phase Control Bit
0:
Shift transmit data on the leading clock edge, latch on trailing edge
1:
Latch receive data on leading clock edge, shift on trailing edge
SSCPO
SSC Clock Polarity Control Bit
0:
Idle clock line is low, leading clock edge is low-to-high transition
1:
Idle clock line is high, leading clock edge is high-to-low transition
SSCTEN
SSC Transmit Error Enable Bit
0:
Ignore transmit errors
1:
Check transmit errors
SSCREN
SSC Receive Error Enable Bit
0:
Ignore receive errors
1:
Check receive errors
SSCPEN
SSC Phase Error Enable Bit
0:
Ignore phase errors
1:
Check phase errors
SSCBEN
SSC Baudrate Error Enable Bit
0:
Ignore baudrate errors
1:
Check baudrate errors
SSCAREN
SSC Automatic Reset Enable Bit
0:
No additional action upon a baudrate error
1:
The SSC is automatically reset upon a baudrate error
SSCMS
SSC Master Select Bit
0:
Slave Mode. Operate on shift clock received via SCLK
1:
Master Mode. Generate shift clock and output it via SCLK
SSCEN
SSC Enable Bit = ‘0’
Transmission and reception disabled. Access to control bits
User’s Manual
12-3
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
SSCCON
SSC Control Reg. (Op.M.)
15
14
13
SSC SSC
EN
= 1 MS
rw
rw
-
12
11
SFR (FFB2H/D9H)
10
9
8
SSC SSC SSC SSC SSC
BSY BE PE RE TE
rw
rw
rw
rw
rw
Reset Value: 0000H
7
6
5
4
3
2
1
-
-
-
-
SSCBC
-
-
-
-
r
0
Bit
Function (Operating Mode, SSCEN = ‘1’)
SSCBC
SSC Bit Count Field
Shift counter is updated with every shifted bit. Do not write to!!!
SSCTE
SSC Transmit Error Flag
1:
Transfer starts with the slave’s transmit buffer not being updated.
SSCRE
SSC Receive Error Flag
1:
Reception completed before the receive buffer was read.
SSCPE
SSC Phase Error Flag
1:
Received data changes around sampling clock edge.
SSCBE
SSC Baudrate Error Flag
1:
More than factor 2 or less than factor 0.5 between Slave’s actual
and expected baudrate.
SSCBSY
SSC Busy Flag
Set while a transfer is in progress. Do not write to!!!
SSCMS
SSC Master Select Bit
0:
Slave Mode. Operate on shift clock received via SCLK.
1:
Master Mode. Generate shift clock and output it via SCLK.
SSCEN
SSC Enable Bit = ‘1’
Transmission and reception enabled. Access to status flags and Master/
Slave (M/S) control.
Note: The target of an access to SSCCON (control bits or flags) is determined by the
state of SSCEN prior to the access, for instance, writing C057H to SSCCON in
programming mode (SSCEN = ‘0’) will initialize the SSC (SSCEN was ‘0’) and then
turn it on (SSCEN = ‘1’).
When writing to SSCCON, make sure that reserved locations receive zeros.
User’s Manual
12-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
The shift register of the SSC is connected to both the transmit pin and the receive pin via
the pin control logic (see block diagram). Transmission and reception of serial data is
synchronized and simultaneous: the same number of bits are transmitted and received.
The major steps of the state machine of the SSC are controlled by the shift clock signal
(see Figure 12-2).
In master mode (SSCMS = ‘1’) two clocks per bit-time are generated, each upon an
underflow of the baudrate counter.
In slave mode (SSCMS = ‘0’) one clock per bit-time is generated, when the latching
edge of the external SCLK signal has been detected.
Transmit data is written into the transmit buffer SSCTB. When the contents of the buffer
are moved to the shift register (immediately if no transfer is currently active) a transmit
interrupt request (SSCTIR) is generated indicating that SSCTB may be reloaded again.
The busy flag SSCBSY is set when the transfer starts (with the next following shift clock
in master mode, immediately in slave mode).
Note: If no data is written to SSCTB prior to a slave transfer, this transfer starts after the
first latching edge of the external SCLK signal is detected. No transmit interrupt is
generated in this case.
When the contents of the shift register are moved to the receive buffer SSCRB after the
programmed number of bits (2 … 16) have been transferred, i.e. after the last latching
edge of the current transfer, a receive interrupt request (SSCRIR) is generated.
The busy flag SSCBSY is cleared at the end of the current transfer (with the next
following shift clock in master mode, immediately in slave mode).
When the transmit buffer is not empty at that time (in the case of continuous transfers)
the busy flag is not cleared and the transfer goes on after moving data from the buffer to
the shift register.
Software should not modify SSCBSY, as this flag is hardware controlled.
Note: Only one SSC (etc.) can be master at a given time.
The transfer of serial data bits can be programmed in many respects:
•
•
•
•
•
•
Data width can be chosen from 2 bits to 16 bits
Transfer may start with the LSB or the MSB
Shift clock may be idle low or idle high
Data bits may be shifted with the leading or trailing edge of the clock signal
Baudrate may be set within a wide range (see baudrate generation)
Shift clock may be generated (master) or received (slave)
This flexibility allows adaptation of the SSC to a wide range of applications which require
serial data transfer.
User’s Manual
12-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
The Data Width Selection supports the transfer of frames of any length from 2-bit
“characters” up to 16-bit “characters”. Starting with the LSB (SSCHB = ‘0’) allows
communication with ASC0 devices in synchronous mode (C166 Family) or 8051-like
serial interfaces, for instance. Starting with the MSB (SSCHB = ‘1’) allows operation
compatible with the SPI interface.
Regardless of which data width is selected and whether the MSB or the LSB is
transmitted first, the transfer data is always right aligned in registers SSCTB and
SSCRB, and the LSB of the transfer data in bit 0 of these registers. The data bits are
rearranged for transfer by the internal shift register logic. The unselected bits of SSCTB
are ignored. The unselected bits of SSCRB will be not valid and should be ignored by
the receiver service routine.
The Clock Control allows adaptation of transmit and receive behavior of the SSC to a
variety of serial interfaces. A specific clock edge (rising or falling) is used to shift out
transmit data, while the other clock edge is used to latch in receive data. Bit SSCPH
selects the leading edge or the trailing edge for each function. Bit SSCPO selects the
level of the clock line in the idle state. Thus, for an idle-high clock, the leading edge is a
falling one, a 1-to-0 transition. Figure 12-3 provides a summary.
Serial Clock
SCLK
SSCPO SSCPH
0
0
0
1
1
0
1
1
Pins
MTSR/MRST
First
Bit
Transmit Data
Last
Bit
MCD01960
Latch Data
Shift Data
Figure 12-3 Serial Clock Phase and Polarity Options
User’s Manual
12-6
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
12.1
Full-Duplex Operation
The various devices are connected through three lines. The definition of these lines is
always determined by the master: The line connected to the master’s data output pin
MTSR is the transmit line, the receive line is connected to its data input line MRST, and
the clock line is connected to pin SCLK. Only the device selected for master operation
generates and outputs the serial clock on pin SCLK. All slaves receive this clock, so their
pin SCLK must be switched to input mode (DP0H.7 = ‘0’). The output of the master’s shift
register is connected to the external transmit line, which in turn is connected to the
slaves’ shift register input. The output of the slaves’ shift register is connected to the
external receive line in order to enable the master to receive the data shifted out of the
slave. The external connections are hard-wired, the function and direction of these pins
are determined by the master or slave operation of the individual device.
Note: The shift direction shown in Figure 12-4 applies for MSB-first operation as well as
for LSB-first operation.
When initializing the devices in this configuration, select one device for master operation
(SSCMS = ‘1’); all others must be programmed for slave operation (SSCMS = ‘0’).
Initialization includes the operating mode of the device’s SSC and also the function of
the respective port lines (see Chapter 12.4).
Master
Device #2
Device #1
Shift Register
MTSR
MRST
Clock
Slave
Shift Register
SCLK
Transmit
Receive
Clock
MTSR
MRST
SCLK
Clock
Slave
Device #3
Shift Register
MTSR
MRST
SCLK
Clock
MCS01963
Figure 12-4 SSC Full-Duplex Configuration
User’s Manual
12-7
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
The data output pins MRST of all slave devices are connected together onto the one
receive line in this configuration. During a transfer, each slave shifts out data from its shift
register. There is an easy way to avoid collisions on the receive line caused by data
from multiple slaves:
Only one slave drives the line, i.e. enables the driver of its MRST pin. All the other slaves
have to program their MRST pins to input. So only one slave can put its data onto the
master’s receive line. Only receiving of data from the master is possible. The master
selects the slave device from which it expects data, either by separate select lines or by
sending a special command to this slave. The selected slave then switches its MRST line
to output, until it gets a deselection signal or command.
After performing all necessary initializations of the SSC, the serial interfaces can be
enabled. For a master device, the alternate clock line will now go to its programmed
polarity. The alternate data line will go to either ‘0’ or ‘1’, until the first transfer starts.
When the serial interfaces are enabled, the master device can initiate the first data
transfer by writing the transmit data into register SSCTB. This value is copied into the
shift register (which is assumed to be empty at this time), and the selected first bit of the
transmit data will be placed onto the MTSR line on the next clock from the baudrate
generator (transmission starts only if SSCEN = ‘1’). Depending on the selected clock
phase, a clock pulse will also be generated on the SCLK line. With the opposite clock
edge, the master at the same time latches and shifts in the data detected at its input line
MRST. This “exchanges” the transmit data with the receive data. Because the clock line
is connected to all slaves, their shift registers will be shifted synchronously with the
master’s shift register, shifting out the data contained in the registers, and shifting in the
data detected at the input line. After the preprogrammed number of clock pulses have
occurred (via the data width selection) the data transmitted by the master is contained in
all slaves’ shift registers, while the master’s shift register holds the data of the selected
slave. In the master and in all slaves, the contents of the shift register are copied into the
receive buffer SSCRB and the receive interrupt flag SSCRIR is set.
A slave device will immediately output the selected first bit (MSB or LSB of the transfer
data) at pin MRST when the contents of the transmit buffer are copied into the slave’s
shift register. It will not wait for the next clock from the baudrate generator, as the master
does. The reason for this is that, depending on the selected clock phase, the first clock
edge generated by the master may be used already to clock in the first data bit. So, the
slave’s first data bit must already be valid at this time.
Note: On the SSC, a transmission and a reception always take place at the same time,
regardless of whether valid data has been transmitted or received. This is different
from asynchronous reception on ASC0.
User’s Manual
12-8
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
Initialization of the SCLK pin on the master requires some attention to avoid undesired
clock transitions which could disturb the other receivers. The state of the internal
alternate output lines is ‘1’ as long as the SSC is disabled. This alternate output signal is
ANDed with the respective port line output latch. Enabling the SSC with an idle-low clock
(SSCPO = ‘0’) will drive the alternate data output and (via the AND) the port pin SCLK
immediately low. To avoid this, use the following sequence:
•
•
•
•
•
Select the clock idle level (SSCPO = ‘x’)
Load the port output latch with the desired clock idle level (P0H.7 = ‘x’)
Switch the pin to output (DP0H.7 = ‘1’)
Enable the SSC (SSCEN = ‘1’)
If SSCPO = ‘0’: enable alternate data output (P0H.7 = ‘1’)
The same mechanism for selecting a slave for transmission (separate select lines or
special commands) may also be used to move the role of the master to another device
in the network. In this case, the previous master and the future master (previous slave)
will need to toggle their operating modes (SSCMS) and the direction of their port pins
(see description above).
User’s Manual
12-9
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
12.2
Half-Duplex Operation
In a half-duplex configuration, only one data line is necessary for both receiving and
transmitting of data. The data exchange line is connected to both pins MTSR and MRST
of each device and the clock line is connected to the SCLK pin.
The master device controls the data transfer by generating the shift clock, while the slave
devices receive it. Due to the fact that all transmit and receive pins are connected to the
one data exchange line, serial data may be moved between arbitrary stations.
As in full-duplex mode, there is an easy way to avoid collisions on the data exchange
line:
• Only the transmitting device may enable its transmit pin driver
Because the data inputs and outputs are connected together, a transmitting device will
clock in its own data at the input pin (MRST for a master device, MTSR for a slave). By
these means, any corruptions on the common data exchange line are detected if the
received data is not equal to the transmitted data.
Master
Device #2
Device #1
Shift Register
Shift Register
MTSR
MTSR
MRST
MRST
Clock
Slave
SCLK
Clock
SCLK
Common
Transmit/
Receive
Line
Clock
Device #3
Slave
Shift Register
MTSR
MRST
SCLK
Clock
MCS01965
Figure 12-5 SSC Half-Duplex Configuration
User’s Manual
12-10
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
12.3
Continuous Transfers
When the transmit interrupt request flag is set, it indicates that the transmit buffer SSCTB
is empty and ready to be loaded with the next transmit data. If SSCTB has been reloaded
by the time the current transmission is finished, the data is immediately transferred to the
shift register and the next transmission will start without any additional delay. On the data
line, there is no gap between the two successive frames. For example, two byte transfers
would look the same as one word transfer. This feature can be used to interface with
devices which can operate with or require more than 16 data bits per transfer. It is only
a matter of software, how long a total data frame length can be. This option can also be
used to interface to byte-wide and word-wide devices on the same serial bus, for
example.
Note: Of course, total frame length can only occur in multiples of the selected basic data
width as disabling/enabling of the SSC would be required to reprogram the basic
data width on-the-fly.
User’s Manual
12-11
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
12.4
Port Control
The SSC uses three pins of PORT0 to communicate with the external world. Pin P0H.7/
SCLK serves as the clock line, while pins P0H.5/MRST (Master Receive/Slave Transmit)
and P0H.6/MTSR (Master Transmit/Slave Receive) serve as the serial data input/output
lines. Operation of these pins depends on the selected operating mode (master or
slave). In order to enable the alternate output functions of these pins instead of the
general purpose IO operation, the respective port latches must be set to ‘1’, because the
port latch outputs and the alternate output lines are ANDed. When an alternate data
output line is not used (function disabled), it is held at a high level, allowing IO operations
via the port latch. The direction of the port lines depends on the operating mode. The
SSC will automatically use the correct alternate input or output line of the ports when
switching modes. The direction of the pins, however, must be programmed by the user,
as shown in the following tables. Table 12-1 summarizes the required values for the
various modes and pins.
Table 12-1
SSC Port Control
Pin
Master Mode
Slave Mode
Function Port Latch
Direction
Function Port Latch
Direction
SCLK
Serial
Clock
Output
P0H.7 = ‘1’
DP0H.7 = ‘1’ Serial
Clock
Input
P0H.7 = ‘x’
DP0H.7 = ‘0’
MTSR
Serial
Data
Output
P0H.6 = ‘1’
DP0H.6 = ‘1’ Serial
Data
Input
P0H.6 = ‘x’
DP0H.6 = ‘0’
MRST
Serial
Data
Input
P0H.5 = ‘x’
DP0H.5 = ‘0’ Serial
Data
Output
P0H.5 = ‘1’
DP0H.5 = ‘1’
Note: In Table 12-1, an ‘x’ means that the actual value is irrelevant in the respective
mode, however, it is recommended to set these bits to ‘1’, so they are already in
the correct state when switching between master and slave modes.
User’s Manual
12-12
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
12.5
Baud Rate Generation
The serial channel SSC has its own dedicated 16-bit baud rate generator with 16-bit
reload capability. This permits baud rate generation independent from the timers.
The baud rate generator is clocked with the CPU clock divided by 2 (fCPU / 2). The timer
counts downwards and can be started or stopped through the global enable bit SSCEN
in register SSCCON. Register SSCBR is the dual-function Baud Rate Generator/Reload
register. Reading SSCBR, while the SSC is enabled, returns the contents of the timer.
Reading SSCBR, while the SSC is disabled, returns the programmed reload value. In
this mode, the desired reload value can be written to SSCBR.
Note: Never write to SSCBR while the SSC is enabled.
The formulas below calculate either the resulting baud rate for a given reload value, or
the required reload value for a given baudrate:
BSSC =
fCPU
fCPU
2 × (<SSCBR> + 1)
,
SSCBR = (
)-1
2 × BaudrateSSC
<SSCBR> represents the contents of the reload register taken as an unsigned 16-bit
integer.
Table 12-2 lists some possible baud rates together with the required reload values and
the resulting bit times, for different CPU clock frequencies.
Table 12-2
SSC Bit-Time Calculation
Bit-time for fCPU = …
16 MHz
20 MHz
25 MHz
Reload Val.
(SSCBR)
33 MHz
Reserved. SSCBR must be > 0.
0000H
250
ns
200
ns
160
ns
121
ns
0001H
375
ns
300
ns
240
ns
182
ns
0002H
500
ns
400
ns
320
ns
242
ns
0003H
625
ns
500
ns
400
ns
303
ns
0004H
1.00
µs
800
ns
640
ns
485
ns
0007H
1.25
µs
1
µs
800
ns
606
ns
0009H
10
µs
8
µs
6.4
µs
4.8
µs
004FH
12.5
µs
10
µs
8
µs
6.1
µs
0063H
15.6
µs
12.5
µs
10
µs
7.6
µs
007CH
20.6
µs
16.5
µs
13.2
µs
10
µs
00A4H
1
ms
800
µs
640
µs
485
µs
1F3FH
User’s Manual
12-13
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
Table 12-2
SSC Bit-Time Calculation (cont’d)
Bit-time for fCPU = …
16 MHz
20 MHz
25 MHz
Reload Val.
(SSCBR)
33 MHz
1.25
ms
1
ms
800
µs
606
µs
270FH
1.56
ms
1.25
ms
1
ms
758
µs
30D3H
8.2
ms
6.6
ms
5.2
ms
4.0
ms
FFFFH
Table 12-3
SSC Baudrate Calculation
Baud Rate for fCPU = …
16 MHz
20 MHz
25 MHz
Reload Val.
(SSCBR)
33 MHz
Reserved. SSCBR must be > 0.
0000H
4.00
Mbit/s
5.00
Mbit/s
6.25
Mbit/s
8.25
Mbit/s
0001H
2.67
Mbit/s
3.33
Mbit/s
4.17
Mbit/s
5.50
Mbit/s
0002H
2.00
Mbit/s
2.50
Mbit/s
3.13
Mbit/s
4.13
Mbit/s
0003H
1.60
Mbit/s
2.00
Mbit/s
2.50
Mbit/s
3.30
Mbit/s
0004H
1.00
Mbit/s
1.25
Mbit/s
1.56
Mbit/s
2.06
Mbit/s
0007H
800
kbit/s
1.0
Mbit/s
1.25
Mbit/s
1.65
Mbit/s
0009H
100
kbit/s
125
kbit/s
156
kbit/s
206
kbit/s
004FH
80
kbit/s
100
kbit/s
125
kbit/s
165
kbit/s
0063H
64
kbit/s
80
kbit/s
100
kbit/s
132
kbit/s
007CH
48.5
kbit/s
60.6
kbit/s
75.8
kbit/s
100
kbit/s
00A4H
1.0
kbit/s
1.25
kbit/s
1.56
kbit/s
2.06
kbit/s
1F3FH
800
bit/s
1.0
kbit/s
1.25
kbit/s
1.65
kbit/s
270FH
640
bit/s
800
bit/s
1.0
kbit/s
1.32
kbit/s
30D3H
122.1 bit/s
User’s Manual
152.6 bit/s
190.7 bit/s
12-14
251.7 bit/s
FFFFH
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
12.6
Error Detection Mechanisms
The SSC is able to detect four different error conditions: Receive Error and Phase Error
are detected in all modes, while Transmit Error and Baudrate Error apply only to slave
mode. When an error is detected, the respective error flag is set. When the
corresponding Error Enable Bit is set, an error interrupt request will also be generated
by setting SSCEIR (see Figure 12-6). The error interrupt handler may then check the
error flags to determine the cause of the error interrupt. The error flags are not reset
automatically (like SSCEIR), but, rather, must be cleared by software after servicing.
This allows servicing of some error conditions via interrupt, while the others may be
polled by software.
Note: The error interrupt handler must clear the associated (enabled) error flag(s) to
prevent repeated interrupt requests.
A Receive Error (Master or Slave mode) is detected when a new data frame is
completely received, but the previous data was not read out of the receive buffer register
SSCRB. This condition sets the error flag SSCRE and, when enabled via SSCREN, the
error interrupt request flag SSCEIR. The old data in the receive buffer SSCRB will be
overwritten with the new value and is irretrievably lost.
A Phase Error (Master or Slave mode) is detected when the incoming data at pin MRST
(master mode) or MTSR (slave mode), sampled with the same frequency as the CPU
clock, changes between one sample before and two samples after the latching edge of
the clock signal (see “Clock Control”). This condition sets the error flag SSCPE and,
when enabled via SSCPEN, the error interrupt request flag SSCEIR.
A Baud Rate Error (Slave mode) is detected when the incoming clock signal deviates
from the programmed baud rate by more than 100%, that is, it either is more than double
or less than half the expected baud rate. This condition sets the error flag SSCBE and,
when enabled via SSCBEN, the error interrupt request flag SSCEIR. Using this error
detection capability requires the slave’s baud rate generator to be programmed to the
same baud rate as the master device. This feature detects false additional pulses or
missing pulses on the clock line (within a certain frame).
Note: If this error condition occurs and bit SSCAREN = ‘1’, an automatic reset of the SSC
will be performed. This is done to reinitialize the SSC if too few or too many clock
pulses have been detected.
User’s Manual
12-15
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
A Transmit Error (Slave mode) is detected when a transfer was initiated by the master
(shift clock gets active), but the transmit buffer SSCTB of the slave was not updated
since the last transfer. This condition sets the error flag SSCTE and, when enabled via
SSCTEN, the error interrupt request flag SSCEIR. If a transfer starts while the transmit
buffer is not updated, the slave will shift out the ‘old’ contents of the shift register, which
normally is the data received during the last transfer.
Note: A slave with push/pull output drivers, which is not selected for transmission, will
normally have its output drivers switched. However, to avoid possible conflicts or
misinterpretations, it is recommended to always load the slave’s transmit buffer
prior to any transfer.
Register SSCCON
SSCTEN
Transmit
Error
SSCEIE
>
–1
SSCEIR
&
Error
Interrupt
SSCEINT
&
SSCPE
SSCBEN
Baudrate
Error
&
SSCRE
SSCPEN
Phase
Error
&
SSCTE
SSCREN
Receive
Error
Register SSCEIC
&
SSCBE
MCA01968
Figure 12-6 SSC Error Interrupt Control
User’s Manual
12-16
V1.0, 2002-02
C164CM/C164SM
Derivatives
High-Speed Synchronous Serial Interface
12.7
SSC Interrupt Control
Three bit-addressable interrupt control registers are provided for serial channel SSC.
Register SSCTIC controls the transmit interrupt, SSCRIC controls the receive interrupt,
and SSCEIC controls the error interrupt of serial channel SSC. Each interrupt source
also has its own dedicated interrupt vector. SCTINT is the transmit interrupt vector,
SCRINT is the receive interrupt vector, and SCEINT is the error interrupt vector.
The cause of an error interrupt request (receive, phase, baudrate, transmit error) can be
identified by the error status flags in control register SSCCON.
Note: In contrast to the error interrupt request flag SSCEIR, the error status flags SSCxE
are not reset automatically upon entry into the error interrupt service routine, but
must be cleared by software.
SSCTIC
SSC Transmit Intr. Ctrl. Reg.
15
14
13
12
11
10
SFR (FF72H/B9H)
9
8
7
6
Reset Value: - - 00H
5
SSC SSC
TIR TIE
-
-
-
-
-
-
SSCRIC
SSC Receive Intr. Ctrl. Reg.
15
14
13
12
11
-
-
rw
9
8
7
6
-
-
-
-
-
SSCEIC
SSC Error Intr. Ctrl. Reg.
15
14
13
12
11
-
-
rw
9
8
7
SSC SSC
EIR EIE
-
-
-
-
-
-
-
-
rw
rw
0
rw
Reset Value: - - 00H
5
4
3
2
1
0
ILVL
GLVL
rw
rw
rw
6
1
rw
SFR (FF76H/BBH)
10
2
GLVL
SFR (FF74H/BAH)
10
3
ILVL
rw
SSC SSC
RIR RIE
-
4
Reset Value: - - 00H
5
4
3
2
1
0
ILVL
GLVL
rw
rw
Note: Please refer to the general Interrupt Control Register description for an
explanation of the control fields.
User’s Manual
12-17
V1.0, 2002-02
C164CM/C164SM
Derivatives
Watchdog Timer (WDT)
13
Watchdog Timer (WDT)
To allow recovery from software or hardware failure, the C164CM provides a Watchdog
Timer. If the software fails to service this timer before an overflow occurs, an internal
reset sequence will be initiated. This internal reset will also pull the RSTOUT pin low,
which in turn resets the peripheral hardware which might have caused the malfunction.
If the watchdog timer is enabled and the software has been designed to service it
regularly before it overflows, the watchdog timer will supervise the program execution so
it will overflow only if the program does not progress properly. The watchdog timer will
also time out if a software error was caused by hardware related failures. This prevents
the controller from malfunctioning for a time longer than specified by the user.
Note: When the bidirectional reset is enabled, pin RSTIN will be pulled low for the
duration of the internal reset sequence upon a software reset or a watchdog timer
reset.
The watchdog timer provides two registers:
• a read-only timer register containing the current count, and
• a control register for initialization and reset source detection.
Reset Indication Pins
RSTOUT
(deactivated by EINIT)
Data Registers
WDT
RSTIN
(bidirectional reset only)
Control Registers
WDTCON
MCA04381
Figure 13-1 SFRs and Port Pins Associated with the Watchdog Timer
The watchdog timer is a 16-bit up counter which is clocked with the prescaled CPU clock
(fCPU). The prescaler divides the CPU clock:
•
•
•
•
by 2 (WDTIN = ‘0’, WDTPRE = ‘0’), or
by 4 (WDTIN = ‘0’, WDTPRE = ‘1’), or
by 128 (WDTIN = ‘1’, WDTPRE = ‘0’), or
by 256 (WDTIN = ‘1’, WDTPRE = ‘1’).
User’s Manual
13-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Watchdog Timer (WDT)
The 16-bit watchdog timer is implemented as two concatenated 8-bit timers (see
Figure 13-2). The upper 8 bits of the watchdog timer can be preset to a
user-programmable value via a watchdog service access in order to vary the watchdog
expire time. The lower 8 bits are reset after each service access.
WDTPRE
WDTIN
÷2
f CPU
MUX
MUX
÷2
÷ 128
WDT Low Byte
WDT High Byte
WDTR
Clear
RSTOUT
Reset
WDT
Control
WDTREL
MCB04470
Figure 13-2 Watchdog Timer Block Diagram
User’s Manual
13-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
Watchdog Timer (WDT)
13.1
Operation of the Watchdog Timer
The current count value of the Watchdog Timer is contained in the Watchdog Timer
Register WDT which is a non-bitaddressable read-only register. Operation of the
Watchdog Timer is controlled by its bitaddressable Watchdog Timer Control Register
WDTCON. This register specifies the reload value for the high byte of the timer, selects
the input clock prescaling factor, and also provides flags to indicate the source of a reset.
After any reset (except as noted) the watchdog timer is enabled and starts counting up
from 0000H with the default frequency fWDT = fCPU / 2. The default input frequency may
be changed to another frequency (fWDT = fCPU / 4, 128, 256) by programming the
prescaler (bits WDTPRE and WDTIN).
The watchdog timer can be disabled by executing the instruction DISWDT (Disable
Watchdog Timer). Instruction DISWDT is a protected 32-bit instruction which will ONLY
be executed during the time between a reset and execution of either the EINIT (End of
Initialization) or the SRVWDT (Service Watchdog Timer) instruction. Either one of these
instructions disables the execution of DISWDT.
Note: After a hardware reset that activates the Bootstrap Loader the watchdog timer will
be disabled. The software reset which terminates the BSL mode will then enable
the WDT.
When the watchdog timer is not disabled via instruction DISWDT it will continue counting
up, even in Idle Mode. If it is not serviced via the instruction SRVWDT by the time the
count reaches FFFFH the watchdog timer will overflow and cause an internal reset. This
reset will pull the external reset indication pin RSTOUT low. The Watchdog Timer Reset
Indication Flag (WDTR) in register WDTCON will be set in this case.
In bidirectional reset mode, pin RSTIN will also be pulled low for the duration of the
internal reset sequence and a long hardware reset will be indicated instead.
A watchdog reset will also complete a running external bus cycle before starting the
internal reset sequence.
To prevent the watchdog timer from overflowing, it must be serviced periodically by the
user software. The watchdog timer is serviced with the instruction SRVWDT which is a
protected 32-bit instruction. Servicing the watchdog timer clears the low byte and reloads
the high byte of the watchdog timer register WDT with the preset value from bitfield
WDTREL which is the high byte of register WDTCON. Servicing the watchdog timer will
also reset bit WDTR. After servicing, the watchdog timer resumes counting up from the
value (<WDTREL> × 28).
Instruction SRVWDT has been encoded in such a way that the chance of unintentionally
servicing the watchdog timer is minimized (such as by fetching and executing a bit
pattern from a wrong location). When instruction SRVWDT does not match the format
for protected instructions, the Protection Fault Trap will be entered, rather than executing
the instruction.
User’s Manual
13-3
V1.0, 2002-02
C164CM/C164SM
Derivatives
Watchdog Timer (WDT)
WDTCON
WDT Control Register
15
14
13
12
11
SFR (FFAEH/D7H)
10
9
8
Reset Value: 00XXH
7
6
5
WDTREL
WDT
PRE
-
-
-
rw
-
-
4
3
2
1
0
LHW SHW SW WDT WDT
R
R
R
R
IN
rh
rh
rh
rh
Bit
Function
WDTIN
Watchdog Timer Input Frequency Select
Controls the input clock prescaler. See Table 13-1.
WDTR
Watchdog Timer Reset Indication Flag
Cleared by a hardware reset or by the SRVWDT instruction.
SWR
Software Reset Indication Flag
SHWR
Short Hardware Reset Indication Flag
LHWR
Long Hardware Reset Indication Flag
WDTPRE
Watchdog Timer Input Prescaler Control
Controls the input clock prescaler. See Table 13-1.
WDTREL
Watchdog Timer Reload Value (for the high byte of WDT)
rw
Note: The reset value depends on the reset source (see description below).
The execution of EINIT clears the reset indication flags.
The time period for an overflow of the watchdog timer is programmable in two ways:
• Input frequency to the watchdog timer can be selected via a prescaler controlled by
bits WDTPRE and WDTIN in register WDTCON to be
fCPU / 2, fCPU / 4, fCPU / 128, or fCPU / 256.
• Reload value WDTREL for the high byte of WDT can be programmed in register
WDTCON.
The period PWDT between servicing the watchdog timer and the next overflow can
therefore be determined by the following formula:
PWDT =
2(1 + <WDTPRE> + <WDTIN> × 6) × (216 - <WDTREL> × 28)
fCPU
User’s Manual
13-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
Watchdog Timer (WDT)
Table 13-1 lists the possible ranges (depending on the prescaler bits WDTPRE and
WDTIN) for the watchdog time which can be achieved using a certain CPU clock.
Table 13-1
Watchdog Time Ranges
CPU Clock Prescaler
16 MHz
20 MHz
25 MHz
33 MHz
WDT
PRE
12 MHz
Reload Value in WDTREL
WDT
IN
fCPU
fWDT
0
0
fCPU / 2
42.67
µs
5.50
ms
10.92
ms
0
1
fCPU / 4
85.33
µs
11.01
ms
21.85
ms
1
0
fCPU / 128
2.73
ms
352.3
ms
699.1
ms
1
1
fCPU / 256
5.46
ms
704.5
ms
1398
ms
0
0
fCPU / 2
32.00
µs
4.13
ms
8.19
ms
0
1
fCPU / 4
64.00
µs
8.26
ms
16.38
ms
1
0
fCPU / 128
2.05
ms
264.2
ms
524.3
ms
1
1
fCPU / 256
4.10
ms
528.4
ms
1049
ms
0
0
fCPU / 2
25.60
µs
3.30
ms
6.55
ms
0
1
fCPU / 4
51.20
µs
6.61
ms
13.11
ms
1
0
fCPU / 128
1.64
ms
211.4
ms
419.4
ms
1
1
fCPU / 256
3.28
ms
422.7
ms
838.9
ms
0
0
fCPU / 2
20.48
µs
2.64
ms
5.24
ms
0
1
fCPU / 4
40.96
µs
5.28
ms
10.49
ms
1
0
fCPU / 128
1.31
ms
169.1
ms
335.5
ms
1
1
fCPU / 256
2.62
ms
338.2
ms
671.1
ms
0
0
fCPU / 2
15.52
µs
2.00
ms
3.97
ms
0
1
fCPU / 4
31.03
µs
4.00
ms
7.94
ms
1
0
fCPU / 128
0.99
ms
128.1
ms
254.2
ms
1
1
fCPU / 256
1.99
ms
256.2
ms
508.4
ms
FFH
7FH
00H
Note: For safety reasons, the user is advised to rewrite WDTCON each time before the
watchdog timer is serviced.
User’s Manual
13-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
Watchdog Timer (WDT)
13.2
Reset Source Indication
Reset indication flags in register WDTCON provide information about the source of the
last reset. As the C164CM starts execution from location 00’0000H after any possible
reset event, the initialization software may check these flags to determine if the recent
reset event was triggered by an external hardware signal (via RSTIN), by software, or by
an overflow of the watchdog timer. The initialization and further operation of the
microcontroller system can thus be adapted to the respective circumstances. For
instance, a special routine may verify software integrity after a watchdog timer reset.
The reset indication flags are not mutually exclusive; more than one flag may be set after
reset depending on its source. Table 13-2 summarizes the possible combinations:
Table 13-2
Reset Indication Flag Combinations
Reset Indication Flags1)
Event
LHWR
SHWR
SWR
WDTR
Long Hardware Reset
1
1
1
0
Short Hardware Reset
∗
1
1
0
Software Reset
∗
∗
1
–
Watchdog Timer Reset
∗
∗
1
1
EINIT instruction
0
0
0
–
SRVWDT instruction
–
–
–
0
1)
Description of table entries:
‘1’ = flag is set, ‘0’ = flag is cleared, ‘–’ = flag is not affected,
‘∗’ = flag is set in bidirectional reset mode, not affected otherwise.
Long Hardware Reset is indicated when the RSTIN input is still sampled low (active) at
the end of a hardware triggered internal reset sequence.
Short Hardware Reset is indicated when the RSTIN input is sampled high (inactive) at
the end of a hardware triggered internal reset sequence.
Software Reset is indicated after a reset triggered by the execution of instruction SRST.
Watchdog Timer Reset is indicated after a reset triggered by an overflow of the
watchdog timer.
Note: When bidirectional reset is enabled, the RSTIN pin is pulled low for the duration of
the internal reset sequence upon any sort of reset.
Therefore a long hardware reset (LHWR) will always be recognized in any case.
User’s Manual
13-6
V1.0, 2002-02
C164CM/C164SM
Derivatives
Real Time Clock
14
Real Time Clock
The Real Time Clock (RTC) module of the C164CM is basically an independent timer
chain clocked directly with the oscillator clock. It serves various purposes:
• System clock to determine the current time and date
• Cyclic time based interrupt
• 48-bit timer for long term measurements
Control Registers
SYSCON2
SYSCON2
T14REL
T14
E
Data Registers
T14REL
Counter Registers
E
Power Management Control Register
Timer T14 Reload Register
Timer T14 Count Register
Interrupt Control
T14
E
ISNC
E
RTCH
E
XP3IC
E
RTCL
E
RTCH
RTCL
ISNC
XP3IC
Real Time Clock Register, High Word
Real Time Clock Register, Low Word
Interrupt Subnode Control Register
RTC Interrupt Control Register
MCA04463
Figure 14-1 SFRs Associated with the RTC Module
The RTC module consists of a chain of 3 divider blocks, a fixed 8:1 divider, the reloadable
16-bit timer T14, and the 32-bit RTC timer (accessible via registers RTCH and RTCL).
Both timers count upwards.
The clock signal for the RTC module is derived directly from the on-chip oscillator
frequency (not from the CPU clock) and is fed through a separate clock driver. It is
therefore independent from the selected clock generation mode of the C164CM and is
controlled by the clock generation circuitry.
Table 14-1
RTC Register Location within ESFR Space
Register
Name
Long / Short
Address
Reset
Value
Notes
T14
F0D2H / 69H
UUUUH
Prescaler timer, generates input clock
for RTC register and periodic interrupt
T14REL
F0D0H / 68H
UUUUH
Timer reload register
RTCH
F0D6H / 6BH
UUUUH
High word of RTC register
RTCL
F0D4H / 6AH
UUUUH
Low word of RTC register
User’s Manual
14-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Real Time Clock
Note: The RTC registers are not affected by a reset. After a power on reset, however,
they are undefined.
T14REL
Reload
T14
8:1
f RTC
Interrupt
Request
RTCH
RTCL
MCD04432
Figure 14-2 RTC Block Diagram
System Clock Operation
A real time system clock can be maintained that keeps on running also during idle mode
and power down mode (optionally) and indicates the current time and date. This is
possible because the RTC module is not affected by a reset.
The maximum resolution (minimum stepwidth) for this clock information is determined by
the input clock of timer T14. The maximum usable timespan is achieved when T14REL
is loaded with 0000H and so T14 divides by 216.
Cyclic Interrupt Generation
The RTC module can generate an interrupt request whenever timer T14 overflows and
is reloaded. This interrupt request may be used, for example, to provide a system time
tick independent of the CPU frequency without loading the general purpose timers, or to
wake up regularly from idle mode. The interrupt cycle time can be adjusted via the timer
T14 reload register T14REL. Please refer to “RTC Interrupt Generation” below for more
details.
48-bit Timer Operation
The concatenation of the 16-bit reload timer T14 and the 32-bit RTC timer can be
regarded as a 48-bit timer which is clocked with the RTC input frequency divided by the
fixed prescaler. The reload register T14REL should be cleared to produce a 48-bit binary
timer. However, any other reload value may be used.
The maximum usable timespan is 248 (≈ 1014) T14 input clocks, which would equal more
than 100 years at an oscillator frequency of 20 MHz.
User’s Manual
14-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
Real Time Clock
RTC Register Access
The actual value of the RTC is indicated by the three registers T14, RTCL and RTCH.
As these registers are concatenated to build the RTC counter chain, internal overflows
occur while the RTC is running. When reading or writing the RTC value, such internal
overflows must be taken into account to avoid reading/writing corrupted values. For
example, reading/writing 0000H to RTCH and then accessing RTCL will produce a
corrupted value as RTCL may overflow before it can be accessed. In this case, however,
RTCH would be 0001H. The same precautions must be taken for T14 and T14REL.
RTC Interrupt Generation
The RTC interrupt shares the XPER3 interrupt node with the PLL/OWD interrupt. This is
controlled by the interrupt subnode control register ISNC. The interrupt handler can
determine the source of an interrupt request via the separate interrupt request and
enable flags (see Figure 14-3) provided in register ISNC.
Note: If only one source is enabled, no additional software check is required, of course.
PLL/OWD
Interrupt
PLLIR
PLLIE
Intr. Request
T14
Interrupt
Intr. Enable
XPER3
Interrupt
Node
Interrupt
Controller
RTCIR
RTCIE
Intr. Request
Intr. Enable
Register ISNC
Register XP3IC
MCA04464
Figure 14-3 RTC Interrupt Logic
If T14 interrupts are to be used both stages the interrupt node (XP3IE = ‘1’) and the RTC
subnode (RTCIE = ‘1’) must be enabled.
Please note that the node request bit XP3IR is automatically cleared when the interrupt
handler is vectored to, while the subnode request bit RTCIR must be cleared by
software.
User’s Manual
14-3
V1.0, 2002-02
C164CM/C164SM
Derivatives
Real Time Clock
Defining the RTC Time Base
The reload timer T14 determines the input frequency of the RTC timer, that is, the RTC
time base, as well as the T14 interrupt cycle time. Table 14-2 lists the interrupt period
range and the T14 reload values (for a time base of 1 s and 1 ms) for several oscillator
frequencies:
Table 14-2
Oscillator
Frequency
RTC Interrupt Periods and Reload Values
RTC Interrupt Period
Reload Value A
Minimum Maximum T14REL Base
Reload Value B
T14REL Base
32 kHz
Main 8000 µs
524.29 s
FF83H
1.000 s
–
–
4 MHz
Main 64.0 µs
4.19 s
C2F7H
1.000 s
FFF0H
1.024 ms
5 MHz
Main 51.2 µs
3.35 s
B3B5H
0.999 s
FFECH
1.024 ms
8 MHz
Main 32.0 µs
2.10 s
85EEH
1.000 s
FFE1H
0.992 ms
10 MHz
Main 25.6 µs
1.68 s
676AH
0.999 s
FFD9H
0.998 ms
12 MHz
Main 21.3 µs
1.40 s
48E5H
1.000 s
FFD2H
1.003 ms
16 MHz
Main 16.0 µs
1.05 s
0BDCH
1.000 s
FFC2H
0.992 ms
Increased RTC Accuracy through Software Correction
The accuracy of the C164CM’s RTC is determined by the oscillator frequency and by the
respective prescaling factor (excluding or including T14). The accuracy limit generated
by the prescaler is due to the quantization of a binary counter (where the average is
zero), while the accuracy limit generated by the oscillator frequency is due to the
difference between the ideal and real frequencies (and therefore accumulates over
time). The total accuracy of the RTC can be further increased via software for specific
applications that demand a high time accuracy.
The key to the improved accuracy is knowledge of the exact oscillator frequency. The
relation of this frequency to the expected ideal frequency is a measure of the RTC’s
deviation. The number of cycles, N, after which this deviation causes an error of ±1 cycle
can be easily computed. So, the only action is to correct the count by ±1 after each series
of N cycles. This correction may be applied to the RTC register as well as to T14.
Also the correction may be made cyclically, for instance, within T14’s interrupt service
routine, or by evaluating a formula when the RTC registers are read (for this the
respective “last” RTC value must be available somewhere).
Note: For the majority of applications, however, the standard accuracy provided by the
RTC’s structure will be more than sufficient.
User’s Manual
14-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
Bootstrap Loader
15
Bootstrap Loader
The built-in bootstrap loader of the C164CM provides a mechanism to load the startup
program, which is executed after reset via the serial interface. In this case, no external
memory or an internal ROM/OTP/Flash is required for the initialization code.
The bootstrap loader moves code/data into the internal RAM, but it is also possible to
transfer data via the serial interface into an external RAM using a second level loader
routine. ROM memory (internal or external) is not necessary. However, it may be used
to provide lookup tables or to provide “core-code” (a set of general purpose subroutines,
for IO operations, number crunching, system initialization, etc.).
RSTIN
P0L.4
or RD
1)
2)
4)
RxD0
3)
TxD0
5)
CSP:IP
6)
Int. Boot ROM BSL-routine
32 bytes
User Software
1)
BSL initialization time, < 70/ fCPU µs, ( fCPU in [MHz]).
Zero byte (1 start Bit, eight '0' data Bits, 1 stop Bit), sent by host.
3) Identification byte, sent by microcontroller.
4) 32 bytes of code / data, sent by host.
5) Caution: TxD0 is only driven a certain time after reception of the zero byte
(< 40/ fCPU µs, fCPU in [MHz])
6) Internal Boot ROM.
2)
MCT04465
Figure 15-1 Bootstrap Loader Sequence
The Bootstrap Loader may be used to load the complete application software into
ROMless systems, it may load temporary software into complete systems for testing or
calibration, or it may be used to load a programming routine for Flash devices.
The BSL mechanism may be used for standard system startup or for special occasions
such as system maintenance (firmware update), end-of-line programming, or testing.
User’s Manual
15-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Bootstrap Loader
15.1
Entering the Bootstrap Loader
The C164CM enters BSL mode triggered by external configuration during a hardware
reset:
• when pin P0L.4 is sampled low at the end of an external reset (EA = ‘0’)
• when pin RD is sampled low at the end of an internal reset (EA = ‘1’).
In this case, the built-in bootstrap loader is activated independent of the selected bus
mode. The bootstrap loader code is stored in a special Boot-ROM, no part of the
standard mask ROM, OTP, or Flash memory area is required for this.
The hardware that activates the BSL during reset may be a simple pull-down resistor on
P0L.4 or RD for systems that use this feature upon every hardware reset. You may want
to use a switchable solution (via jumper or an external signal) for systems that only
temporarily use the bootstrap loader.
Ext.
Signal
Start
Boot
RD
P0L.4
RD
RD
~2 k
Ext.
Signal
Start
Boot
P0L.4
~2 k
Proposal for Internal Reset
(EA = '1')
~8 k
Ext.
Signal
Start
Boot
P0L.4
~8 k
Proposal for Internal Reset
(EA = '0')
Proposal for Combined Circuitry
MCA04466
Figure 15-2 Hardware Provisions to Activate the BSL
The ASC0 receiver is only enabled after the identification byte has been transmitted. A
half-duplex connection to the host is therefore sufficient to feed the BSL.
Note: The proper reset configuration for BSL mode requires more pins to be driven
besides P0L.4 or RD.
For an external reset (EA = ‘0’) bitfield SMOD must be configured as 1011B (see
Section 20.4.1).
For an internal reset (EA = ‘1’) pin ALE must be driven to a defined level, e.g.
ALE = ‘0’ for the standard bootstrap loader (see Section 20.4.2).
User’s Manual
15-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
Bootstrap Loader
Initial State in BSL Mode
After entering BSL mode and the appropriate initialization1) the C164CM scans the RxD0
line to receive a zero byte, that is, one start bit, eight ‘0’ data bits and one stop bit. From
the duration of this zero byte, it calculates the corresponding baudrate factor with respect
to the current CPU clock, initializes the serial interface ASC0 accordingly, and switches
pin TxD0 to output. Using this baudrate, an identification byte is returned to the host that
provides the data to be loaded.
This identification byte identifies the device to be booted using the following codes:
55H:
A5H:
B5H:
C5H:
D5H:
8xC166.
Previous versions of the C167 (obsolete).
Previous versions of the C165.
C167 derivatives.
All devices equipped with identification registers.
Note: The identification byte D5H does not directly identify a specific derivative. That
information can be obtained from the identification registers.
When the C164CM has entered BSL mode, the following configuration is automatically
set (values that deviate from the normal reset values, are marked):
Watchdog Timer:
Context Pointer CP:
Stack Pointer SP:
Register S0CON:
Register S0BG:
Disabled
FA00H
FA40H
8011H
acc. to ‘00’ byte
Register STKUN:
Register STKOV:
Register BUSCON0:
P0H.3/TxD0:
DP0H.3:
FC00H
F600H
acc. to startup config.
‘1’
‘1’
Other than after a normal reset the watchdog timer is disabled, so the bootstrap loading
sequence is not time limited. Pin TxD0 is configured as output, so the C164CM can
return the identification byte.
Note: Even if the internal ROM/OTP/Flash is enabled, no code can be executed out of
it while the C164CM is in BSL mode.
1)
The external host should not send the zero byte before the end of the BSL initialization time (see Figure 15-1)
to ensure that it is correctly received.
User’s Manual
15-3
V1.0, 2002-02
C164CM/C164SM
Derivatives
Bootstrap Loader
Memory Configuration after Reset
After reset in Bootstrap-Loader mode, the configuration (i.e. the accessibility) of the
C164CM’s memory areas differs from the standard case. Pin EA is not evaluated when
BSL mode is selected and accesses to the internal code memory are partly redirected
while the C164CM is in BSL mode (see Table 15-1). All code fetches are made from the
special Boot-ROM, while data accesses read from the internal code memory. Data
accesses will return undefined values on ROMless devices.
Note: The code in the Boot-ROM is not an invariant feature of the C164CM. User
software should not try to execute code from the internal ROM area while the BSL
mode is still active, as these fetches will be redirected to the Boot-ROM.
The Boot-ROM will also “move” to segment 1, when the internal ROM area is
mapped to segment 1.
16 MBytes
16 MBytes
16 MBytes
255
255
BSL Memory Configurations
255
Int.
RAM
1
Int.
RAM
Boot-ROM
Access to
int. ROM
enabled
MCA04383
1
Depends
on reset
config.
(EA, P0)
Int.
RAM
0
User ROM
0
Boot-ROM
Access to
external
bus
enabled
0
Access to
int. ROM
enabled
MCA04384
User ROM
1
Access to
external
bus
disabled
User ROM
Table 15-1
Depends
on reset
config.
MCA04385
BSL mode active
Yes
Yes
No
EA pin
high
low
acc. to application
Code fetch from
internal ROM area
Boot-ROM access
Boot-ROM access
User ROM access
Data fetch from
internal ROM area
User ROM access
User ROM access
User ROM access
User’s Manual
15-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
Bootstrap Loader
15.2
Loading the Startup Code
After sending the identification byte, the BSL enters a loop to receive 32 bytes via ASC0.
These bytes are stored sequentially in locations 00’FA40H through 00’FA5FH of the
internal RAM. Up to 16 instructions may be placed in the RAM area. To execute the
loaded code, the BSL then jumps to location 00’FA40H, i.e. the first loaded instruction.
The bootstrap loading sequence is now terminated, but, the C164CM remains in BSL
mode. Most probably, the initially loaded routine will load additional code or data, as an
average application is likely to require substantially more than 16 instructions. This
second receive loop may use the pre-initialized interface ASC0 directly to receive data
and store it to arbitrary user-defined locations.
This second level of loaded code may be the final application code. It may also be
another, more sophisticated, loader routine that adds a transmission protocol to enhance
the integrity of the loaded code or data. It may also contain a code sequence to change
the system configuration and enable the bus interface to store the received data into
external memory.
This process may go through several iterations or may directly execute the final
application. In all cases, the C164CM will continue to run in BSL mode, with the
watchdog timer disabled and limited access to the internal code memory. All code
fetches from the internal ROM area (00’0000H … 00’7FFFH or 01’0000H … 01’7FFFH, if
mapped to segment 1) are redirected to the special Boot-ROM. Data fetches access will
access the internal code memory of the C164CM, if any is available, but will return
undefined data on ROMless devices.
Note: Data fetches from a protected ROM will not be executed.
15.3
Exiting Bootstrap Loader Mode
In order to execute a program in normal mode (i.e. watchdog timer active, full access to
user memory, etc.), the BSL mode must first be terminated. The C164CM exits BSL
mode in two ways:
• upon a software reset, ignoring the external configuration (P0L.4 or RD)
• upon a hardware reset, not configuring BSL mode.
After the non-BSL reset, the C164CM will start executing out of user memory as
externally configured via PORT0 or RD/ALE (depending on EA).
User’s Manual
15-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
Bootstrap Loader
15.4
Choosing the Baudrate for the BSL
Calculation of the serial baudrate for ASC0 from the length of the first zero byte received
allows the bootstrap loader of the C164CM to operate with a wide range of baudrates.
However, the upper and lower limits must be maintained in order to ensure proper data
transfer.
f
CPU
B C164CM = ----------------------------------------------32 × ( S0BRL + 1 )
The C164CM uses timer T3 to measure the length of the initial zero byte. The
quantization uncertainty of this measurement implies the first deviation from the real
baudrate. The next deviation is implied by the computation of the S0BRL reload value
from the timer contents. The formula below shows the association:
T3 – 18
S0BRL = -------------------36
,
9 f CPU
T3 = --- × -------------8 B Host
For a correct data transfer from the host to the C164CM the maximum deviation between
the internal initialized baudrate for ASC0 and the real baudrate of the host should be
below 2.5%. The deviation (FB, in percent) between host baudrate and C164CM
baudrate can be calculated via the formula below:
B Contr – B Host
F B = ------------------------------------ × 100%
B Contr
,
F B ≤ 2,5%
Note: Function (FB) does not consider the tolerances of oscillators and other devices
supporting the serial communication.
This baudrate deviation is a nonlinear function depending on the CPU clock and the
baudrate of the host. The maxima of the function (FB) increase with the host baudrate
due to the smaller baudrate prescaler factors and the implied higher quantization error
(see Figure 15-3).
User’s Manual
15-6
V1.0, 2002-02
C164CM/C164SM
Derivatives
Bootstrap Loader
Ι
FB
2.5%
B Low
B High
B Host
ΙΙ
MCA02260
Figure 15-3 Baudrate Deviation between Host and C164CM
The minimum baudrate (BLow in Figure 15-3) is determined by the maximum count
capacity of timer T3, when measuring the zero byte, thus, it depends on the CPU clock.
The minimum baudrate is obtained by using the maximum T3 count 216 in the baudrate
formula. Baudrates below BLow would cause T3 to overflow. In this case, ASC0 cannot
be initialized properly and the communication with the external host is likely to fail.
The maximum baudrate (BHigh in Figure 15-3) is the highest baudrate at which the
deviation still does not exceed the limit; thus, all baudrates between BLow and BHigh are
below the deviation limit. BHigh marks the baudrate up to which communication with the
external host will work properly without additional tests or investigations.
Higher baudrates, however, may be used if the actual deviation does not exceed the
indicated limit. A certain baudrate (marked I) in Figure 15-3) may violate the deviation
limit, while an even higher baudrate (marked II) in Figure 15-3) stays very well below it.
Any baudrate can be used for the bootstrap loader provided that the following three
prerequisites are fulfilled:
• Baudrate is within the specified operating range for the ASC0
• External host is able to use this baudrate
• Computed deviation error is below the limit.
Table 15-2
fCPU [MHz]
Bootstrap Loader Baudrate Ranges
10
12
16
20
25
BMAX
312,500
375,000
500,000
625,000
781,250
BHigh
9,600
19,200
19,200
19,200
38,400
BSTDmin
600
600
600
600
600
BLow
172
206
275
343
429
User’s Manual
15-7
V1.0, 2002-02
C164CM/C164SM
Derivatives
Bootstrap Loader
Note: When the bootstrap loader mode is entered via an internal reset (EA = ‘1’), the
default configuration selects the prescaler for clock generation. In this case the
bootstrap loader will begin to operate with fCPU = fOSC / 2 which will limit the
maximum baudrate for ASC0 at low input frequencies intended for PLL operation.
Higher levels of the bootstrapping sequence can then switch the clock generation
mode for example to PLL operation (via register RSTCON) to achieve higher
baudrates for the subsequent download.
User’s Manual
15-8
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
16
Capture/Compare Unit CAPCOM2
The C164CM provides a Capture/Compare (CAPCOM) unit which provides 16 channels
(12 IO pins) which interact with 2 timers. The CAPCOM2 unit can capture the contents
of a timer on specific internal or external events, or can compare a timer’s contents with
given values and modify output signals in case of a match. This mechanism supports
generation and control of timing sequences on up to 16 channels with a minimum of
software intervention.
From the programmer’s point of view, the term ‘CAPCOM unit’ refers to a set of Special
Function Registers (SFRs) associated with this peripheral, including the port pins which
may be used for alternate input/output functions including their direction control bits.
Ports & Direction Control
Alternate Functions
Data Registers
Control Registers
Interrupt Control
T78CON
T1IC
E
T8IC
E
T7
E
T7REL
E
T8
E
DP8
T8REL
E
P8
CC16-19
CCM4
CC20-23
CCM5
CC24-27
CCM6
CC28-31
CCM7
E
DP1H
P1H
E
ODP8
CC16IO/P8.0...CC19IO/P8.3
CC24IO/P1H.4...CC27IO/P1H.7
CC28IO/P1H.0...CC31IO/P1H.3
ODP8
DPx
Px
Port 8 Open Drain Control Register
Port x Direction Control Register
Port x Data Register
TxREL
Tx
CC16...19
CC20...23
CC24...27
CC28...31
CCM4
CCM5
CCM6
CCM7
CAPCOM2 Timer x Reload Register
CAPCOM2 Timer x Register
CAPCOM2 Register 16...19
CAPCOM2 Register 20...23
CAPCOM2 Register 24...27
CAPCOM2 Register 28...31
CAPCOM2 Mode Control Register 4
CAPCOM2 Mode Control Register 5
CAPCOM2 Mode Control Register 6
CAPCOM2 Mode Control Register 7
CC16-19IC
E
CC24-27IC
E
T78CON
CAPCOM2 Timers T7 and
T8 Control Register
TxIC
CAPCOM2 Timer x Interrupt
Control Register
CC16...19IC CAPCOM2 Interrupt
Control Register 16...19
CC24...27IC CAPCOM2 Interrupt
Control Register 24...27
MCA05137
Figure 16-1 SFRs and Port Pins Associated with the CAPCOM2 Unit
User’s Manual
16-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
The CAPCOM2 unit is typically used to handle high speed IO tasks such as pulse and
waveform generation, pulse width modulation, or recording of the time at which specific
events occur. It also allows the implementation of up to 16 software timers. The
maximum resolution of the CAPCOM2 unit is 8 CPU clock cycles (= 16 TCL).
The CAPCOM2 unit consists of a bank of 16 dual-purpose 16-bit capture/compare
registers (CC16 through CC31) and two 16-bit timers (T7/T8). Each has its own reload
register (TxREL).
The input clock for the CAPCOM2 timers is programmable to several prescaled values
of the CPU clock, or it can be derived from an overflow/underflow of timer T3 in block
GPT1. T7 may also operate in counter mode (from an external input) where it can be
clocked by external events.
Each capture/compare register may be programmed individually for the capture or
compare function, and each register may be allocated to either timer. Eight capture/
compare registers have an associated port pin which serves as an input pin for the
capture function or as an output pin for the compare function. The capture function
causes the current timer contents to be latched into the respective capture/compare
register triggered by an event (transition) on its associated port pin. The compare
function may cause an output signal transition on that port pin whose associated
capture/compare register matches the current timer contents. Specific interrupt requests
are generated upon each capture/compare event or upon timer overflow.
Figure 16-2 shows the basic structure of the CAPCOM2 unit.
User’s Manual
16-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
Reload Reg. TxREL
fCPU
2n : 1
Tx
Input
Control
CAPCOM Timer Tx
Mode
Control
(Capture
or
Compare)
16-Bit
Capture/
Compare
Registers
Ty
Input
Control
CAPCOM Timer Ty
TxIN
Interrupt
Request
(TxIR)
GPT1 Timer T3
Over/Underflow
CCzIO
Capture Inputs
Compare Outputs
Capture/Compare
Interrupt Request
CCzIO
fCPU
2n : 1
GPT1 Timer T3
Over/Underflow
x=7
y=8
z = 16 … 19, 24 … 31
Interrupt
Request
(TyIR)
Reload Reg. TyREL
MCA05086
Figure 16-2 CAPCOM2 Unit Block Diagram
Table 16-1
Unit
CAPCOM2 Channel Port Connections
Channel
Port
Capture
Compare
P8.3 … P8.0
Input
Output
CC20IO … CC23IO
–
–
–
CC24IO … CC27IO
P1H.7 … P1H.4 Input
Output
CC28IO … CC31IO
P1H.0 … P1H.3 Input
Output
Σ = 16
Σ = 12
Σ = 12
CAPCOM2 CC16IO … CC19IO
User’s Manual
16-3
Σ = 12
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
16.1
CAPCOM2 Timers
The primary use of the timers T7 and T8 is to provide two independent time bases
(16 TCL maximum resolution) for the capture/compare registers of the CAPCOM2 unit,
but they may also be used independent of the capture/compare registers.
The basic structure of the two timers is identical, but the selection of input signals is
different for timer T7 and timer T8 (see Figure 16-3 and Figure 16-4).
Reload Reg. TxREL
Txl
fCPU
Input
Control
2n : 1
GPT1 Timer T3
Over/Underflow
CAPCOM Timer Tx
MUX
Edge
Select
Interrupt
Request
TxR
TxI TxM
TxIN
TxI
x=7
MCB05088
Figure 16-3 Block Diagram of CAPCOM Timer T7
Reload Reg. TxREL
Txl
fCPU
2n : 1
CAPCOM Timer Tx
MUX
GPT1 Timer T3
Over/Underflow
Interrupt
Request
TxR
x=8
TxM
MCB05089
Figure 16-4 Block Diagram of CAPCOM Timer T8
User’s Manual
16-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
The functions of the CAPCOM timers are controlled via the bit-addressable 16-bit control
register T78CON. The high-byte of T78CON controls T8, the low-byte of T78CON
controls T7. The control options are identical for both timers (except for external input).
T78CON
CAPCOM Timer 7/8 Ctrl. Reg.
15
14
13
12
11
-
T8R
-
-
T8M
-
rw
-
-
rw
10
SFR (FF20H/90H)
9
8
Reset Value: 0000H
7
6
5
4
3
2
1
T8I
-
T7R
-
-
T7M
T7I
rw
-
rw
-
-
rw
rw
0
Bit
Function
TxI
Timer/Counter x Input Selection
Timer Mode (TxM = ‘0’)
Input Frequency = fCPU / 2(<TxI> + 3)
See also table below for examples.
Counter Mode (TxM = ‘1’): 000 Overflow/Underflow of GPT1 Timer 3
001 Positive (rising) edge on pin T7IN1)
010 Negative (falling) edge on pin T7IN1)
011 Any edge (rising and falling) on pin T7IN1)
1XX Reserved
TxM
Timer/Counter x Mode Selection
0:
Timer Mode (Input derived from internal clock)
1:
Counter Mode (Input from External Input or T3)
TxR
Timer/Counter x Run Control
0:
Timer/Counter x is disabled
1:
Timer/Counter x is enabled
1)
This selection is available for timer T7. Timer T8 will stop at this selection!
The timer run flags T7R and T8R allow the timers to be enabled or disabled. The
following description of the timer modes and operation always applies to the enabled
state of the timers, that is, the respective run flag is assumed to be set to ‘1’.
In all modes, the timers always count upwards. The current timer values are accessible
for the CPU in the timer registers Tx, which are non-bitaddressable SFRs. When the CPU
writes to a register Tx in the state immediately before the respective timer increment or
reload is to be performed, the CPU write operation has priority and the increment or
reload is disabled to guarantee correct timer operation.
User’s Manual
16-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
Timer Mode
The bits TxM in SFR T78CON select between timer mode or counter mode for the
respective timer. In timer mode (TxM = ‘0’), the input clock for a timer is derived from the
internal CPU clock divided by a programmable prescaler. The different options for the
prescaler are selected separately for each timer by the bit fields TxI.
The input frequencies fTx for Tx are determined as a function of the CPU clock as
follows, where <TxI> represents the contents of the bit field TxI:
fTx =
fCPU
2(<TxI> + 3)
When a timer overflows from FFFFH to 0000H, it is reloaded with the value stored in its
respective reload register TxREL. The reload value determines the period PTx between
two consecutive overflows of Tx as follows:
PTx =
(216 - <TxREL>) × 2(<TxI> + 3)
fCPU
After a timer has been started by setting its run flag (TxR) to ‘1’, the first increment will
occur within the time interval defined by the selected timer resolution. All further
increments occur exactly after the time defined by the timer resolution.
When both timers of the CAPCOM2 unit are to be incremented or reloaded at the same
time, T7 is always serviced one CPU clock before T8.
The timer input frequencies, resolution and periods which result from the selected
prescaler option in TxI when using a certain CPU clock are listed in Table 16-2 Table 16-4. The numbers for the timer periods are based on a reload value of 0000H.
Note that some numbers may be rounded to 3 significant digits.
User’s Manual
16-6
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
Table 16-2
Timer Input Frequencies, Resolution and Period @ 20 MHz
fCPU = 20 MHz
Timer Input Selection TxI
000B
001B
010B
011B
100B
101B
110B
111B
8
16
32
64
128
256
512
1024
Input Frequency 2.5
MHz
1.25
MHz
625
kHz
312.5
kHz
156.25 78.125 39.06
kHz
kHz
kHz
19.53
kHz
Resolution
400
ns
800
ns
1.6
µs
3.2
µs
6.4
µs
12.8
µs
25.6
µs
51.2
µs
Period
26
ms
52.5
ms
105
ms
210
ms
420
ms
840
ms
1.68
s
3.36
s
Prescaler (1:N)
Table 16-3
Timer Input Frequencies, Resolution and Period @ 25 MHz
fCPU = 25 MHz
Timer Input Selection TxI
000B
001B
010B
011B
100B
101B
110B
111B
8
16
32
64
128
256
512
1024
Input Frequency 3.125
MHz
1.563
MHz
781.25 390.63 195.31 97.656 48.828 24.414
kHz
kHz
kHz
kHz
kHz
kHz
Resolution
320
ns
640
ns
1.28
µs
2.56
µs
5.12
µs
10.24
µs
20.48
µs
40.96
µs
Period
21
ms
42
ms
84
ms
168
ms
336
ms
672
ms
1.344
s
2.688
s
Prescaler (1:N)
Table 16-4
Timer Input Frequencies, Resolution and Period @ 33 MHz
fCPU = 33 MHz
Timer Input Selection TxI
000B
001B
010B
011B
100B
101B
110B
111B
8
16
32
64
128
256
512
1024
Input Frequency 4.125
MHz
2.063
MHz
1.031
MHz
515.63 257.81 128.91 64.453 32.227
kHz
kHz
kHz
kHz
kHz
Resolution
242
ns
485
ns
970
ns
1.94
µs
15.52
µs
31.03
µs
Period
15.89
ms
31.78
ms
63.55
ms
127.10 254.20 508.40 1.017
ms
ms
ms
s
2.034
s
Prescaler (1:N)
User’s Manual
16-7
3.88
µs
7.76
µs
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
Counter Mode
The bits TxM in SFR T78CON select between timer mode or counter mode for the
respective timer. In Counter mode (TxM = ‘1’) the input clock for a timer can be derived
from the overflows/underflows of timer T3 in block GPT1. Additionally, timer T7 can be
clocked by external events. Either a positive, a negative, or both a positive and a
negative transition at pin T7IN (alternate port input function) can be selected to cause an
increment of T7.
When T8 is programmed to run in counter mode, bit field TxI is used to enable the
overflows/underflows of timer T3 as the count source. This is the only option for T8 and
it is selected by the combination TxI = 000B. When bit field TxI is programmed to any
other valid combination, the respective timer will stop.
When T7 is programmed to run in counter mode, bit field TxI is used to select the count
source and transition (if the source is the input pin) which should cause a count trigger
(see description of T78CON for the possible selections).
Note: To use pin T7IN as external count input pin, the respective port pin must be
configured as input: the corresponding direction control bit must be cleared
(DPx.y = ‘0’).
If the respective port pin is configured as output, the associated timer may be
clocked by modifying the port output latches Px.y via software, such as for testing
purposes.
The maximum external input frequency to T7 in counter mode is fCPU/16. To ensure that
a signal transition is properly recognized at the timer input, an external count input signal
should be held for at least eight CPU clock cycles before it changes its level again. The
incremented count value appears in SFR T7 within eight CPU clock cycles after the
signal transition at pin T7IN.
Reload
In both modes, a reload of a timer with the 16-bit value stored in its associated reload
register is performed each time a timer would overflow from FFFFH to 0000H. In such a
case, the timer does not wrap around to 0000H, but rather is reloaded with the contents
of the respective reload register TxREL. The timer then resumes incrementing starting
from the reloaded value.
The reload registers TxREL are not bit-addressable.
User’s Manual
16-8
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
16.2
CAPCOM2 Unit Timer Interrupts
When a timer overflows, the corresponding timer interrupt request flag TxIR for the
respective timer will be set. This flag can be used to generate an interrupt or to trigger a
PEC service request, when enabled by the respective interrupt enable bit TxIE.
Each timer has its own bit-addressable interrupt control register (TxIC) and its own
interrupt vector (TxINT). The organization of the interrupt control registers TxIC is
identical to the other interrupt control registers.
T7IC
CAPCOM T7 Intr. Ctrl. Reg.
15
14
13
12
11
ESFR (F17AH/BEH)
10
9
8
7
6
Reset Value: - - 00H
5
T7IR T7IE
-
-
-
-
-
-
T8IC
CAPCOM T8 Intr. Ctrl. Reg.
15
14
13
12
11
-
-
rwh
9
8
7
6
-
-
-
-
-
-
-
rwh
rw
2
1
0
GLVL
rw
rw
ESFR (F17CH/BFH)
10
3
ILVL
rw
T8IR T8IE
-
4
Reset Value: - - 00H
5
4
3
2
1
0
ILVL
GLVL
rw
rw
Note: Please refer to the general Interrupt Control Register description for an
explanation of the control fields.
User’s Manual
16-9
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
16.3
Capture/Compare Registers
The 16-bit capture/compare registers CC16 through CC31 are used as data registers for
capture or compare operations with respect to timers T7 and T8. The capture/compare
registers are not bit-addressable.
Each of the registers CCx may be individually programmed for capture mode or for one
of four different compare modes. Each register may be allocated individually to one of
the two timers T7 or T8, respectively. A special combination of compare modes
additionally allows implementation of a ‘double-register’ compare mode. When capture
or compare operation is disabled for one of the CCx registers, it may be used for general
purpose variable storage.
Capture/Compare Mode Registers for the CAPCOM2 Unit
The functions of the 16 capture/compare registers are controlled by four, identically
organized bit-addressable 16-bit mode control registers named CCM4 … CCM7 (see
description below). Each register contains bits for mode selection and timer allocation of
four capture/compare registers.
Capture/Compare Mode Registers for the CAPCOM2 Unit (CC16 … CC31)
CCM4
CAPCOM Mode Ctrl. Reg. 4
15
14
13
12
11
SFR (FF22H/91H)
10
9
8
7
6
Reset Value: 0000H
5
4
3
2
1
0
ACC
19
CCMOD19
ACC
18
CCMOD18
ACC
17
CCMOD17
ACC
16
CCMOD16
rw
rw
rw
rw
rw
rw
rw
rw
CCM5
CAPCOM Mode Ctrl. Reg. 5
15
14
13
12
11
SFR (FF24H/92H)
10
9
8
7
6
Reset Value: 0000H
5
4
3
2
1
0
ACC
23
CCMOD23
ACC
22
CCMOD22
ACC
21
CCMOD21
ACC
20
CCMOD20
rw
rw
rw
rw
rw
rw
rw
rw
CCM6
CAPCOM Mode Ctrl. Reg. 6
15
14
13
12
11
SFR (FF26H/93H)
10
9
8
7
6
Reset Value: 0000H
5
4
3
2
1
0
ACC
27
CCMOD27
ACC
26
CCMOD26
ACC
25
CCMOD25
ACC
24
CCMOD24
rw
rw
rw
rw
rw
rw
rw
rw
User’s Manual
16-10
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
CCM7
CAPCOM Mode Ctrl. Reg. 7
15
14
13
12
11
SFR (FF28H/94H)
10
9
8
7
6
Reset Value: 0000H
5
4
3
2
1
0
ACC
31
CCMOD31
ACC
30
CCMOD30
ACC
29
CCMOD29
ACC
28
CCMOD28
rw
rw
rw
rw
rw
rw
rw
rw
Bit
Function
CCMODx
Mode Selection for Capture/Compare Register CCx
The available capture/compare modes are listed in Table 16-5.
ACCx
Allocation Bit for Capture/Compare Register CCx
0:
CCx allocated to Timer T7
1:
CCx allocated to Timer T8
Table 16-5
Selection of Capture Modes and Compare Modes
CCMODx
Selected Operating Mode
000
Disable Capture and Compare Modes
The respective CAPCOM2 register may be used for general variable
storage.
001
Capture on Positive Transition (Rising Edge) at Pin CCxIO
010
Capture on Negative Transition (Falling Edge) at Pin CCxIO
011
Capture on Positive and Negative Transition (Both Edges) at Pin CCxIO
100
Compare Mode 0:
Interrupt Only
Several interrupts per timer period. Enables double-register compare mode
for registers CC24 … CC27.
101
Compare Mode 1:
Toggle Output Pin on each Match
Several compare events per timer period. This mode is required for
double-register compare mode for registers CC16 … CC19.
110
Compare Mode 2:
Interrupt Only
Only one interrupt per timer period.
111
Compare Mode 3:
Set Output Pin on each Match
Reset output pin on each timer overflow; Only one interrupt per timer
period.
The descriptions of the capture and compare modes are valid for all capture/compare
channels; so, the registers, bits, and pins are referenced only by the placeholder ‘x’.
User’s Manual
16-11
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
Note: Capture/compare channels 16 … 19 and 24 … 31 are connected to pins,
capture/compare channels 16 … 19 and 24 … 27 are connected to and interrupt
nodes.
A capture or compare event on channel 27 may be used to trigger a channel
injection on the C164CM’s A/D converter, if enabled.
16.4
Capture Mode
In response to an external event, the contents of the associated timer (T7 or T8,
depending on the state of the allocation control bit ACCx) are latched into the respective
capture register CCx. The external event causing a capture can be programmed to be a
positive, a negative, or both a positive and a negative transition at the respective external
input pin CCxIO.
The triggering transition is selected by the mode bits CCMODx in the respective
CAPCOM mode control register. In any case, the event causing a capture will also set
the respective interrupt request flag CCxIR, which can cause an interrupt or a PEC
service request, when enabled.
Edge
Select
Capture Reg. CCx
Interrupt
Request
CCxIO
CCMODx
Input
Clock
CAPCOM Timer Ty
x = 27...24, 19...16
y = 7, 8
Interrupt
Request
MCB05120
Figure 16-5 Capture Mode Block Diagram
Note: Capture events can also be triggered by inputs CC31IO … CC28IO. However,
these channels have no dedicated interrupt request. See Section 16.7 for a
possible solution.
User’s Manual
16-12
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
To use the respective port pin as external capture input pin CCxIO for capture register
CCx, this port pin must be configured as input; that is, the corresponding direction control
bit must be set to ‘0’. To ensure that a signal transition is properly recognized, an external
capture input signal should be held for at least eight CPU clock cycles before changing
its level.
During these eight CPU clock cycles, the capture input signals are scanned sequentially.
When a timer is modified or incremented in this process, the new timer contents will
already be captured for the remaining capture registers within the current scanning
sequence.
Note: When the timer modification can generate an overflow the capture interrupt
routine should check if the timer overflow was serviced during these 8 CPU clock
cycles.
If pin CCxIO is configured as output, the capture function may be triggered by modifying
the corresponding port output latch via software, for testing purposes, for example.
User’s Manual
16-13
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
16.5
Compare Modes
The compare modes allow triggering of events (interrupts and/or output signal
transitions) with minimum software overhead. In all compare modes, the 16-bit value
stored in compare register CCx (in the following also referred to as ‘compare value’) is
continuously compared with the contents of the allocated timer (T7 or T8). If the current
timer contents match the compare value, an appropriate output signal, based on the
selected compare mode, can be generated at the corresponding output pin CCxIO and
the associated interrupt request flag CCxIR is set, which can generate an interrupt
request (if enabled). See Section 16.7 for a possible solution for channels 28 … 31.
As for capture mode, the compare registers are also processed sequentially in compare
mode. When any two compare registers are programmed to the same compare value,
their corresponding interrupt request flags will be set to ‘1’ and the selected output
signals will be generated within eight CPU clock cycles after the allocated timer is
incremented to the compare value. Further compare events on the same compare value
are disabled1) until the timer is incremented again or is written to by software. After a
reset, compare events for register CCx will become enabled only if the allocated timer
has been incremented or written to by software and one of the compare modes
described in the following sections has been selected for this register.
The different compare modes which can be programmed for a given compare register
CCx are selected by the mode control field CCMODx in the associated capture/compare
mode control register. Each of the compare modes, including the special ‘double
register’ mode, is discussed in detail in the following sections.
Compare Mode 0
This is an interrupt-only mode which can be used for software timing purposes. Compare
mode 0 is selected for a given compare register CCx by setting bit field CCMODx of the
corresponding mode control register to ‘100B’.
In this mode, the interrupt request flag CCxIR is set each time a match is detected
between the contents of compare register CCx and the allocated timer. Several of these
compare events are possible within a single timer period, when the compare value in
register CCx is updated during the timer period. The corresponding port pin CCxIO is not
affected by compare events in this mode and can be used as general purpose IO pin.
If compare mode 0 is programmed for one of the registers CC24 … CC27, the
double-register compare mode becomes enabled for this register if the corresponding
bank 1 register is programmed to compare mode 1 (see “Double-Register Compare
Mode” on Page 16-19).
1)
Compare events are detected sequentially, where a sequence (checking 8 times 2 channels each) takes
8 CPU clock cycles. Even if more sequences are executed before the timer increments (lower timer frequency)
a given compare value only results in one single compare event.
User’s Manual
16-14
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
Interrupt
Request
Compare Reg. CCx
Toggle
(Mode 1)
Comparator
Port
Latch
CCxIO
CCMODx
Input
Clock
Interrupt
Request
CAPCOM Timer Ty
x = 31 … 16 (not all channels are connected to port pins and interrupt nodes)
y = 7, 8
MCB02016a
Figure 16-6 Compare Mode 0 and 1 Block Diagram
Note: The port latch and pin remain unaffected in compare mode 0.
In the example shown in Figure 16-7, the compare value in register CCx is modified from
cv1 to cv2 after compare events #1 and #3, and from cv2 to cv1 after events #2 and #4,
etc. This results in periodic interrupt requests from timer Ty, and in interrupt requests
from register CCx which occur at the time specified by the user through cv1 and cv2.
Contents of Ty
FFFFH
Compare Value cv2
Compare Value cv1
Reload Value<TyREL>
0000H
Interrupt
Requests:
TyIR
t
CCxIR
Event #1
CCx: = cv2
CCxIR TyIR
Event #2
CCx: = cv1
CCxIR
Event #3
CCx: = cv2
CCxIR TyIR
Event #4
CCx: = cv1
Output pin CCxIO only effected in mode 1. No changes in mode 0.
x = 31...16
y = 7, 8
MCB05119
Figure 16-7 Timing Example for Compare Modes 0 and 1
User’s Manual
16-15
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
Compare Mode 1
Compare mode 1 is selected for register CCx by setting bit field CCMODx of the
corresponding mode control register to ‘101B’.
When a match between the content of the allocated timer and the compare value in
register CCx is detected in this mode, interrupt request flag CCxIR is set to ‘1’ (where
connected), and the corresponding output pin CCxIO (alternate port output function) is
toggled. For this purpose, the state of the respective port output latch (not the pin) is
read, inverted, and then written back to the output latch.
Compare mode 1 allows several compare events within a single timer period. An
overflow of the allocated timer has no effect on the output pin, nor does it disable or
enable further compare events.
In order to use the respective port pin as compare signal output pin CCxIO for compare
register CCx in compare mode 1, this port pin must be configured as output, i.e. the
corresponding direction control bit must be set to ‘1’. With this configuration, the initial
state of the output signal can be programmed or its state can be modified at any time by
writing to the port output latch.
In compare mode 1 the port latch is toggled upon each compare event (see
Figure 16-7).
If compare mode 1 is programmed for one of the registers CC16 … CC19, the
double-register compare mode becomes enabled for this register if the corresponding
bank 2 register is programmed to compare mode 0 (see “Double-Register Compare
Mode” on Page 16-19).
Note: If the port output latch is written to by software at the same time it would be altered
by a compare event, the software write will have priority. In this case, the
hardware-triggered change will not become effective.
Only capture/compare channels 16 … 19 and 24 … 27 are connected to pins.
Compare Mode 2
Compare mode 2 is an interrupt-only mode similar to compare mode 0; but, only one
interrupt request per timer period will be generated. Compare mode 2 is selected for
register CCx by setting bit field CCMODx of the corresponding mode control register to
‘110B’.
When a match is detected in compare mode 2 for the first time within a timer period, the
interrupt request flag CCxIR is set to ‘1’. The corresponding port pin is not affected and
can be used for general purpose IO. However, after the first match has been detected in
this mode, all further compare events within the same timer period are disabled for
compare register CCx until the allocated timer overflows. This means that after the first
match, even when the compare register is reloaded with a value higher than the current
timer value, no compare event will occur until the next timer period.
User’s Manual
16-16
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
In the example shown in Figure 16-8, the compare value in register CCx is modified from
cv1 to cv2 after compare event #1. Compare event #2, however, will not occur until the
next period of timer Ty.
Interrupt
Request
Compare Reg. CCx
Set
(Mode 3)
Reset
Comparator
Port
Latch
CCxIO
CCMODx
Input
Clock
Interrupt
Request
CAPCOM Timer Ty
x = 31 … 16 (not all channels are connected to port pins and interrupt nodes)
y = 7, 8
MCB02019a
Figure 16-8 Compare Mode 2 and 3 Block Diagram
Note: The port latch and pin remain unaffected in compare mode 2.
Contents of Ty
FFFF H
Compare Value cv2
Compare Value cv1
Reload Value<TyREL>
0000 H
Interrupt
Requests:
TyIR
CCxIR
TyIR
CCxIR TyIR
State
CCxIO:
1
Event #1
CCx: = cv2
Event #2
CCx: = cv1
Output pin CCxIO only effected in mode 3. No changes in mode 2.
0
time
x = 31...16
y = 7, 8
MCB05121
Figure 16-9 Timing Example for Compare Modes 2 and 3
User’s Manual
16-17
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
Compare Mode 3
Compare mode 3 is selected for register CCx by setting bit field CCMODx of the
corresponding mode control register to ‘111B’. In compare mode 3, only one compare
event will be generated per timer period.
When the first match within the timer period is detected, the interrupt request flag CCxIR
is set to ‘1’ (where connected) and the output pin CCxIO (alternate port function) will be
set to ‘1’. The pin will be reset to ‘0’, when the allocated timer overflows.
If a match was found for register CCx in this mode, all further compare events during the
current timer period are disabled for CCx until the corresponding timer overflows. If, after
a match was detected, the compare register is reloaded with a new value, this value will
not become effective until the next timer period.
To use the respective port pin as compare signal output pin CCxIO for compare register
CCx in compare mode 3, this port pin must be configured as output: the corresponding
direction control bit must be set to ‘1’. With this configuration, the initial state of the output
signal can be programmed or its state can be modified at any time by writing to the port
output latch.
In compare mode 3, the port latch is set upon a compare event and cleared upon a timer
overflow (see Figure 16-9).
However, when compare value and reload value for a channel are equal, the respective
interrupt requests will be generated. Only the output signal is not changed in this case
(set and clear would coincide).
Note: If the port output latch is written to by software at the same time it would be altered
by a compare event, the software write will have priority. In such a case, the
hardware-triggered change will not become effective.
Only capture/compare channels 16 … 19 and 24 … 31 are connected to pins,
capture/compare channels 16 … 19 and 24 … 27 are connected to interrupt
nodes.
User’s Manual
16-18
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
Double-Register Compare Mode
In double-register compare mode, two compare registers work together to control one
output pin. This mode is selected by a special combination of modes for these two
registers.
For double-register mode, the 16 capture/compare registers of the CAPCOM2 unit are
regarded as two banks of 8 registers each. Registers CC16 … CC23 form bank 1 while
registers CC24 … CC31 form bank 2 (respectively). For double-register mode, a bank 1
register and a bank 2 register form a register pair. Both registers of this register pair
operate on the pin associated with the bank 1 register (pins CC16IO … CC19IO are
available).
The relationships between the bank 1 and bank 2 registers of a pair and the affected
output pins for double-register compare mode are listed in Table 16-6.
Table 16-6
Register Pairs for Double-Register Compare Mode
CAPCOM2 Unit
Register Pair
Associated Output Pin
Bank 1
Bank 2
CC16
CC24
CC16IO
CC17
CC25
CC17IO
CC18
CC26
CC18IO
CC19
CC27
CC19IO
CC23 … CC20
CC31 … CC28
-----
The double-register compare mode can be programmed individually for each register
pair. To enable double-register mode, the respective bank 1 register (see Table 16-6)
must be programmed to compare mode 1 and the corresponding bank 2 register (see
Table 16-6) must be programmed to compare mode 0.
If the respective bank 1 compare register is disabled or programmed for a mode other
than mode 1 the corresponding bank 2 register will operate in compare mode 0
(interrupt-only mode).
In the following example, a bank 2 register (programmed to compare mode 0) will be
referred to as CCz while the corresponding bank 1 register (programmed to compare
mode 1) will be referred to as CCx.
User’s Manual
16-19
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
When a match is detected for one of the two registers in a register pair (CCx or CCz) the
associated interrupt request flag (CCxIR or CCzIR) is set to ‘1’ and pin CCxIO
corresponding to bank 1 register CCx is toggled. The generated interrupt always
corresponds to the register that caused the match.
Note: If a match occurs simultaneously for register CCx and register CCz of the register
pair, pin CCxIO will be toggled only once but two separate compare interrupt
requests will be generated: one for vector CCxINT and one for vector CCzINT.
To use the respective port pin as compare signal output pin CCxIO for compare register
CCx in double-register compare mode, this port pin must be configured as output: the
corresponding direction control bit must be set to ‘1’. With this configuration, the output
pin has the same characteristics as in compare mode 1.
Interrupt
Request
Compare Reg. CCx
Mode 1 (CCMODx)
Comparator
Input
Clock
CAPCOM Timer Ty
1
Toggle
Port
Latch
CCxIO
Comparator
Mode 0 (CCMODz)
Compare Reg. CCz
Interrupt
Request
x = 19...16 (not all channels are connected to port pins and interrupt nodes)
y = 7, 8
z = 27...24
MCB05122
Figure 16-10 Double-Register Compare Mode Block Diagram
User’s Manual
16-20
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
In this configuration example, the same timer allocation was chosen for both compare
registers, but each register may also be allocated individually to one of the two timers of
the CAPCOM2 unit. In the timing example for this compare mode (Figure 16-11), the
compare values in registers CCx and CCz are not modified.
Note: The pins CCzIO (which do not serve for double-register compare mode) may be
used for general purpose IO.
Contents of Ty
FFFF H
Compare Value CCz
Compare Value CCx
Reload Value<TyREL>
0000 H
Interrupt
Requests:
TyIR
CCxIR
CCxIR TyIR
CCxIR
State of CCxIO:
CCxIR TyIR
1
0
time
x = 19...16
y = 7, 8
z = 27...24
MCB05123
Figure 16-11 Timing Example for Double-Register Compare Mode
Note: Double-Register Compare Mode is reasonable only on channel pairs with an
associated output pin.
User’s Manual
16-21
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
16.6
Capture/Compare Interrupts
Upon a capture or compare event on channels 16 … 19 and 24 … 27, the interrupt
request flag CCxIR for the respective capture/compare register CCx is set to ‘1’. This flag
can be used to generate an interrupt or to trigger a PEC service request when enabled
by the interrupt enable bit CCxIE.
Capture interrupts can be regarded as external interrupt requests with the additional
feature of recording the time at which the triggering event occurred (see also
Section 5.8).
Each of the 8 capture/compare registers listed above has its own bit-addressable
interrupt control register (CC27IC … CC24IC, CC19IC … CC16IC) and its own interrupt
vector (CC27INT … CC24INT, CC19INT … CC16INT). These registers are organized
the same way as all other interrupt control registers. The basic register layout is shown
here. Table 16-7 lists the associated addresses.
CCxIC
CAPCOM Intr. Ctrl. Reg.
15
14
13
12
11
ESFR (See Table 16-7)
10
9
8
7
6
CCx CCx
IR
IE
-
-
-
-
-
-
-
-
rwh
rw
Reset Value: - - 00H
5
4
3
2
1
0
ILVL
GLVL
rw
rw
Note: Please refer to the general Interrupt Control Register description for an
explanation of the control fields.
Table 16-7
CAPCOM2 Unit Interrupt Control Register Addresses
CAPCOM2 Unit
Register Name
Address
Register Space
CC16IC
F160H / B0H
ESFR
CC17IC
F162H / B1H
ESFR
CC18IC
F164H / B2H
ESFR
CC19IC
F166H / B3H
ESFR
CC24IC
F170H / B8H
ESFR
CC25IC
F172H / B9H
ESFR
CC26IC
F174H / BAH
ESFR
CC27IC
F176H / BBH
ESFR
User’s Manual
16-22
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM2
16.7
Interrupts for the Upper CAPCOM Channels
The upper four CAPCOM channels (CC28IO … CC31IO) are not connected to the
respective interrupt nodes (CC28IC … CC31IC). However, these signals share the same
pins as the fast external interrupts EX0IN … EX3IN. Due to this fact the missing interrupt
nodes can be replaced.
Instead of the dedicated interrupt nodes for the CAPCOM registers 28 … 31 the fast
external interrupts 0 … 3 can be enabled if the corresponding pin is used as capture input
or compare output (compare modes 1 and 3). Register EXICON selects the interrupt
edge, registers CC8IC … CC11IC control interrupt enables and levels.
This means that CAPCOM channel 28 triggers external interrupt signal EX0IN and
requests an interrupt via node CC8IC. The other three channels are associated
accordingly (see Table 5-9).
User’s Manual
16-23
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17
Capture/Compare Unit CAPCOM6
The CAPCOM6 unit of the C164CM has been designed for applications which require
digital signal generation and/or event capturing, such as pulse width modulation (PWM)
or measuring. The C164CM supports generation and control of timing sequences on up
to three 16-bit capture/compare channels plus one 10-bit compare channel.
In compare mode the CAPCOM6 unit provides two output signals per 16-bit channel
which may have inverted polarity and non-overlapping pulse transitions. The 10-bit
compare channel can generate a single PWM output signal and is further used to
modulate the capture/compare output signals. The compare timers T12 (16-bit) and T13
(10-bit) are free running timers which are clocked by the prescaled CPU clock.
For motor control applications both subunits may generate versatile multi-channel PWM
signals which are basically either controlled by compare timer T12 or by a typical hall
sensor pattern at the interrupt inputs. This operating mode is called block commutation
(available only in devices with a full function CAPCOM6).
In capture mode the contents of compare timer T12 are stored in the capture registers
upon a programmable signal transition at pins CC6x.
From the programmer’s point of view, the term ‘CAPCOM unit’ refers to a set of SFRs
which are associated with this peripheral, including the port pins which may be used for
alternate input/output functions and their direction control bits.
Ports & Direction Control
Alternate Functions
DP1H
E
P1H
CC6POS2...0/P1H.2...0
CTRAP/P1L.7
COUT63/P1L.6
COUT62, CC62/P1L.5, P1L.4
COUT61, CC61/P1L.3, P1L.2
COUT60, CC60/P1L.1, P1L.0
Data Registers
Control Registers
Interrupt Control
T12IC
E
T13IC
E
T12P
E
CTCON
T12OF
E
TRCON
T13P
E
CMP13
CC60
CC6MCON
CC6EIC
E
CC61
CC6MSELE
CC6CIC
E
CC62
CC6MIC
DP1HPort P1H Direction Control Register
P1HPort P1H Data Register
TxPCAPCOM6 Timer x Period Register
T12OFCAPCOM6 Timer T12 Offset Register
CMP13CAPCOM6 Timer T13 Compare Register
CTCONCAPCOM6 Timer Control Register
CC60...62CAPCOM6 Register 0...2
TRCONCAPCOM6 Trap Control Register
CC6MCONCAPCOM6 Mode Control Register
CC6MSELCAPCOM6 Mode Select Register
CC6MICCAPCOM6 Mode Intr. Control Register
CC6EICCAPCOM6 Emergency Intr. Control Reg.
CC6CICCAPCOM6 Channel Intr. Control Register
Note: The resources marked in italic are available only in the full function CAPCOM6.
MCA05113
Figure 17-1 SFRs and Port Pins Associated with the CAPCOM6 Unit
User’s Manual
17-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
The three 16-bit capture/compare channels are driven via timer T12 and each can
control two output lines (see Port Control Logic). The offset register T12OF (full function
module only) allows shifting of the switching points of the COUT6x output line of each
channel by shifting the respective compare value.
The 10-bit compare channel is driven via timer T13 and can control one output line.
Additional control logic allows the capture/compare channel outputs to be combined with
the compare channel output or with external signals. Thus flexible and complex output
patterns can be generated automatically, with very little or no CPU action.
Mode
Select Register
CC6MSEL
Offset Register
T12OF
Compare
Timer T12
16-Bit
Trap Register
CC Channel 1
CC61
CC Channel 2
CC62
CTRAP
CC60
COUT60
CC Channel 0
CC60
Control
fCPU
Prescaler
Period Register
T12P
Port
Control
Logic
CC61
COUT61
CC62
COUT62
fCPU
Prescaler
Control Register
CTCON
Compare
Timer T13
10-Bit
Compare Register
CMP13
COUT63
Block
Commutation
Control
CC6MCON.H
Period Register
T13P
CC6POS0
CC6POS1
CC6POS2
MCB04109
1)
These registers are not directly accessable.
The period and offset registers are loading a value into the timer registers.
Figure 17-2 CAPCOM6 Block Diagram
Two basic operating modes are supported:
• Edge-Aligned Mode
• Center-Aligned Mode
In Edge Aligned Mode the compare timer counts up starting at 0000H. Upon reaching
the period value stored in register TxP the timer is cleared and repeats counting up. At
this time the output signals are also switched to their passive state. Edge aligned mode
is supported by both compare timers, T12 and T13.
User’s Manual
17-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
In Center Aligned Mode the compare timer T12 counts up starting at 0000H. Upon
reaching the period value stored in register T12P the count direction is reversed and the
timer counts down. The output signals are switched to their active/passive state upon a
match with the compare value while counting up/down. Center aligned mode is
supported by compare timer T12 only.
The compare timers T12 and T13 are free running timers which are clocked with a
programmable frequency of fCPU to fCPU/128.
The respective output signals are changed (if appropriate) when the timer reaches the
programmed compare value. For switching the output signals COUT60 … COUT62 the
contents of the timer plus the offset value are compared against the compare value.
Timer T12 can operate in either edge aligned or center aligned PWM mode (see
Figure 17-3), with or without a constant edge delay (a or b in Figure 17-3).
Timer T13 can operate in edge aligned mode without edge delay.
Compare Timer T12 in Edge Aligned Mode
a) Standard PWM
b) Standard PWM with dead time (tOFF)
Period
Value
Period
Value
Compare
Value
Compare
Value
0000 H
Offset
{
tOFF
CC6x
CC6x
COUT6x
COUT6x
MCB04110
Compare Timer T12 in Center Aligned Mode
c) Symmetrical PWM
d) Symmetrical PWM with dead time (tOFF)
Period
Value
Period
Value
Compare
Value
Compare
Value
0000 H
Offset
{
tOFF
tOFF
CC6x
CC6x
Initial value ‘0’
COUT6x
COUT6x
Initial value ‘1’
: Interrupt can be generated
MCB03356
Figure 17-3 CAPCOM6 Basic Operating Modes
User’s Manual
17-3
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.1
Output Signal Level Control
The output signals generated by the CAPCOM6 unit are characterized by the duration
of their active and passive phases which define the signals’ period and duty cycle. In
order to adapt these output signals to the requirements of a specific application, the logic
level of the passive state for each signal can be selected via register CC6MCON.
When using the trap function, the outputs are switched to their trap level upon the
activation of an external (emergency) signal. The trap level is defined via the respective
port output latches.
Note: Changing the state levels during operation of CAPCOM6 will immediately affect
the output signals. It is recommended that the output levels be defined during
initialization before the output signals are assigned and before the CAPCOM6 unit
is started.
In burst and multi-channel modes the signals generated by the capture/compare
channels may additionally be modulated by the signal generated by the 10-bit compare
channel. Optionally, this compare channel signal may be inverted before modulating the
other outputs. The compare channel’s signal may be output on pin COUT63. This output
function is enabled by bit ECT13O in register CTCON. If the output function is disabled
COUT63 drives the defined passive level.
Note: Trap function and multi-channel modes are available in the full function module
only.
User’s Manual
17-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.2
Edge Aligned Mode
The compare timer counts up starting at 0000H. When the timer contents match the
respective compare value in register CC6x the associated output signal is switched to
its active state. Upon reaching the period value stored in register TxP the timer is cleared
and repeats counting up. At this time also the output signals are switched to their passive
state.
In Figure 17-4 the selected edge offset is zero, therefore the output signal refers to
CC6x and/or COUT6x.
T12 Value
7
7
6
CCP = 7
6
5
5
4
4
3
T12OF = 0
2
2
1
1
0
T12 Start
*)
3
3
2
0
4
1
Time
0
(CC = 0)
Duty
Cycles:
100%
(CC = 1)
87.5%
(CC = 4)
50%
(CC = 7)
12.5%
(CC
7)
"0"
0%
CC = compare value in registers CC6x
CCP = period value in register T12P T13P
*)
Output signal at pin CC6x or COUT6x selected as active high.
For an active low output the signals would appear inverted.
MCT04111
Figure 17-4 Operation in Edge Aligned Mode
The example above shows how to generate PWM output signals with duty cycles
between 0% and 100%, including the corner values. The duty cycle directly corresponds
to the programmed compare value. The indicated output signals can be output on the
respective pin CC6x or COUT6x, or both. The pin allocation is controlled via bitfields
CMSELx in register CC6MSEL. Register CC6MCON selects the passive level for
enabled outputs. The example above uses active high signals: the passive level is low
(the associated select bit is ‘0’).
User’s Manual
17-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
In Figure 17-5 a non-zero offset value is used. In this case the compare value is not
compared with the timer contents directly, but rather with timer contents plus offset. As
a consequence the active edge of signal COUT6x is shifted against CC6x.
Figure 17-5 shows some of the output signals that can be generated (compare value =
‘3’):
a) Standard output signal, using T12 directly, active high.
b) Shifted output signal, using T12 + T12OF, active high.
c) Same signal as b), but active low.
d) 0% output signal, compare value in CC6x > T12P + T12OF.
e) 100% output signal, compare value in CC6x = T12OF.
T12+T12O
F
Count Value
9
9
8
7
3
T12OF = 2
3
1
2
5
T12
3
2
3
2
Time
1
0
tOFF
4
4
1
0
T12 Start
3
2
6
4
4
T12
6
5
5
4
3
2
7
7
6
5
5
4
2
7
6
6
T12P = 7
8
0
tOFF
tOFF
a)
b)
c)
"0"
0%
d)
100%
e)
MCT02602
Figure 17-5 Operation with Non-zero Offset
Note: Offset operation is only available in the full function module and is possible for the
three capture/compare channels on timer T12 only. The compare channel on
timer T13 does not provide an offset register and has no second output signal.
User’s Manual
17-6
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.3
Center Aligned Mode
The three capture/compare channels associated with T12 may operate in center aligned
mode. The compare timer T12 counts up starting at 0000H. When the timer contents
match the respective compare value in register CC6x, the associated output signal CC6x
is switched to its active state (while counting up). Upon reaching the period value stored
in register T12P the count direction is reversed and the timer counts down. When the
timer contents match the respective compare value in register CC6x, the associated
output signal CC6x is switched to its passive state (while counting down).
The output signals COUT6x are switched upon matches of register CC6x with
T12 + T12OF. Non-zero offset values shift the COUT6x edges symmetrically against the
CC6x edges (see Figure 17-6). This allows the generation of non-overlapping signal
pairs CC6x/COUT6x with arbitrary active levels. These signal pairs may e.g. be used to
drive the high and low side switches of a power bridge without the risk of a branch
shortcut (prevented by the programmable dead-time tOFF, see Figure 17-6).
T12+T12O
F
Count Value
9
T12P = 7
7
6
5
3
2
5
7
7
6
7
6
6
T12
5
6
5
4
4
T12OF = 2
8
8
4
3
3
2
3
3
2
2
1
1
0
T12 Start
5
4
4
5
4
3
2
Time
1
0
tOFF
tOFF
tOFF
CC6x
(Active High)
Duty
Cycles:
29%
COUT6x
(Active High)
57%
COUT6x
(Active Low)
57%
CC6x = 5 (in this example)
MCT02603
Figure 17-6 Operation in Center Aligned Mode
Note: In order to generate correct dead times for PWM signals, the offset value stored
in T12OF must be lower than the value stored in the compare registers.
The offset value affects all COUT6x outputs.
Dead time generation is available only in the full function module.
User’s Manual
17-7
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.3.1
Timing Relationships
The resolution of the compare timers depends on the selected internal clock frequency.
The period range of the output signals in turn depends on the actual timer resolution
(minimum value) and on the timer and period values (maximum value). Table 17-1 lists
the respective values of both compare timers for the possible clock selections.
Due to internal operation the minimum possible output period is two internal clock cycles.
Edge Aligned Mode
Count Value
CC6x = 2
T12P = 3
1
CC6x = 2
T12P = 5
2
5
4
T12 Start
CC6x = 1
T12P = 2
2
1
1
0
0
3
3
3
2
1
2
1
0
Time
1
0
0
0
CCx/
COUTx
min. 4 TCL
MCT04112
Center Aligned Mode
Count Value
CC6x = 1
T12P = 4
T12 Start
CC6x = 1
T12P = 2
1
4
3
2
1
0
2
1
1
0
2
1
1
0
3
3
2
2
1
1
Time
0
CCx/
COUTx
min. 4 TCL
MCT02604
Figure 17-7 Operation in Center Aligned Mode
User’s Manual
17-8
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
Table 17-1
Compare Timer Resolution and Period Range as Function of the
Internal Clock @ fCPU = 20 MHz
Internal
Clock
Cmp. Timer
Resolution
Output Signal Period Range (Txmin. - T12max. / T13max.)
fCPU
50
ns
100 ns
- 3.28 ms
/ 51.2 µs
200 ns
- 6.55 ms
fCPU / 2
100
ns
200 ns
- 6.55 ms
/ 102.4 µs
400 ns
- 13.11 ms / 204.8 µs
fCPU / 4
200
ns
400 ns
- 13.11 ms / 204.8 µs
800 ns
- 26.21 ms / 409.6 µs
fCPU / 8
400
ns
800 ns
- 26.21 ms / 409.6 µs
1.6 µs
- 52.43 ms / 819.2 µs
fCPU / 16
800
ns
1.6 µs
- 52.43 ms / 819.2 µs
3.2 µs
- 104.86 ms / 1.64 ms
fCPU / 32
1.6
µs
3.2 µs
- 104.86 ms / 1.64 ms
6.4 µs
- 209.72 ms / 3.28 ms
fCPU / 64
3.2
µs
6.4 µs
- 209.72 ms / 3.28 ms
12.8 µs - 419.43 ms / 6.55 ms
fCPU / 128 6.4
µs
12.8 µs - 419.43 ms / 6.55 ms
25.6 µs - 838.86 ms / 13.1 ms
Edge Aligned Mode
Center Aligned Mode
/ 102.4 µs
Compare timer Tx period and duty cycle values can be calculated using the formulas
below. The following abbreviations are used in these formulas:
pv = period value, stored in register TxP
ov = offset value, stored in register T12OF
cv = compare value, stored in register CC6x or CMP13
Note: For compare timer T13 only the output signal COUT63 in edge aligned mode is
available.
Edge Aligned Mode:
Period value = pv + 1
Duty cycle of CC6x outputs =
1-
cv
× 100%
pv + 1
1-
Duty cycle of COUT6x outputs =
cv - o v
× 100%
pv + 1
Center Aligned Mode:
Period value = 2 × pv
Duty cycle of CC6x outputs =
1-
Duty cycle of COUT6x outputs =
User’s Manual
cv
pv
1-
17-9
× 100%
cv - o v
× 100%
pv
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.4
Burst Mode
In burst mode the output signal COUT63 of the 10-bit compare channel modulates the
active phases of the output signals COUT6x of the three capture/compare channels.
Burst mode is not possible on the CC6x outputs. The modulating signal typically has a
higher frequency than the modulated output channels. Figure 17-8 shows an example
for a waveform generated in burst mode.
Burst mode is enabled separately for each capture/compare output by setting the
respective bit CMSELx3 in register CC6MSEL.
Count Value
Period
Register
T12
Compare
Register
T12 Start
Time
Active
Low
CMSELx3 = 0
Burst Mode
Disabled
Active
High
T13
COUT63
COUTXI = 1
COUTXI = 0
COUT6x
Active
Low
COUTXI = 0
COUTXI = 1
COUT6x
Active
High
MCT02605
Figure 17-8 Operation in Burst Mode
User’s Manual
17-10
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.5
Capture Mode
Each of the three capture/compare channels can be programmed individually for capture
mode via bitfields CMSELx in register CC6MSEL. In capture mode the contents of timer
T12 are copied to the channel’s compare register CC6x upon a selectable transition
(rising, falling, or both) at the associated pin CC6x. Capture mode can be enabled either
in edge aligned mode or in center aligned mode. Interrupts may be generated selectively
at each transition of the capture input signal.
Pins CC6x (used as inputs in capture mode) are sampled every CPU clock period.
When evaluating a series of capture events, it must be noted that every capture event
overwrites the previous value in the respective register CC6x. The control software must
be designed to retrieve the capture values before they are overwritten.
User’s Manual
17-11
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.6
Combined Multi-Channel Modes
Note: Multi-channel modes are available in the full function module only.
When operating in a combined multi-channel mode, the output signals CC6x and
COUT6x are controlled by the compare timers and additional conditions. Multi-channel
modes are selected via register CC6MCON. In these modes a predefined signal pattern
sequence is driven to the output lines.
Note: Compare timer T12 must be enabled (CT12R = ‘1’) in order to enable proper
operation of the multi-channel modes.
Multi-phase modes allow the effective generation of output signal patterns, for 4 … 6
phase unipolar drives, for example. The phase sequence can be controlled automatically
by T12 overflows or by software.
Block Commutation mode is a special multi-channel mode which especially supports
the control of brushless DC drives. In this mode the phase sequence is controlled by
three input signals (CC6POSx) generated by the drive (via hall sensors, for instance).
In all modes the output signals can be modulated during their active phases.
Emergency
Interrupt
CC6POS0
CC6POS1
CC6POS2
Trap Control
CTRAP
Port
Control
Logic
CC60
CC61
CC62
COUT60
COUT61
COUT62
Multi
Channel
Control
Capture
Event
PWM
Channel 0 in
Capture Mode
Period/
Match
Interrupt
Timer T13
COUT63
Timer T12
MCB04113
Figure 17-9 Multi-Channel Mode Control
User’s Manual
17-12
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.6.1
Output Signals in Multi-Channel Mode
In multi-channel mode the output signals are controlled primarily by the selected phase
sequence (see sequence tables below). Each output is active for two phases and
remains passive for all other phases of a sequence.
The active phases of each output signal may additionally be modulated by T12 or T13.
For unmodulated active phases timer T12 must operate with 100% duty cycle, that is its
offset and compare registers must be cleared, and T13 modulation must be off (bits
CMSELx3 must be cleared). T12 modulation is effective when T12’s duty cycle is
programmed below 100%, T13 modulation is enabled via bits CMSELx3 (see examples
in Figure 17-10).
Trigger *)
Start
T12
CC60
COUT61
CC60
COUT60
COUT62
2
Unmodulated
Active Phase
1
5
4
3
Modulated
by T12
2
1
5
4
3
Modulated
by T13
*) The trigger that switches to the next phase may be a T12 overflow or a ‘1’
being written to bit NMCS via software. In block commutation mode the trigger
is represented by a change in the input pattern on pins CC6POSx.
The shown waveforms are active high.
MCA05114
Figure 17-10 Basic Five-Phase Multi-Channel Timing
User’s Manual
17-13
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
Figure 17-10 shows the five-phase output waveforms as an example. For the other
modes each passive phase is shortened or lengthened by one sequence phase,
respectively.
The compare output signals are enabled according to the intended multi-phase mode.
Table 17-2 lists the required coding:
Table 17-2
Programming of Multi-Channel PWM Outputs
Multi-Channel PWM Mode
CMSEL2
CMSEL1
CMSEL0
Block commutation mode
011B
011B
011B
4-phase multi-channel PWM
011B
010B
001B
5-phase multi-channel PWM
011B
010B
011B
6-phase multi-channel PWM
011B
011B
011B
Note: Bit CMSELx3 (burst mode bit) defines whether or not the signal at the COUT6x
pins is modulated by compare timer T13 (CMSELx3 = ‘1’). T13 modulation may
be combined with T12 modulation.
Phase Sequence Tables
The following tables list the phase sequences for the various multi-phase modes. The
sequence is defined via the follower state for each state and also the output levels for
each state are listed.
The states of a phase sequence are switched in one of two ways:
• Automatic switching on a T12 overflow
• Software controlled by setting bit NMCS in register CC6MSEL.
Bit ESMC = ‘1’ enables software controlled state switching and disables automatic
switching on T12 overflows.
Note: The actual logic levels for active and passive state are defined in register
CC6MCON.
In four-phase, five-phase and six-phase multi-channel PWM mode all output
signals can be modulated by timer T12 or timer T13 during their active phases.
User’s Manual
17-14
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
State
Table 17-3
Four-Phase PWM Sequence Table
Output Level Definition (for actual state)
Follower State (for BCM = …)
CC60
COUT61 CC62
COUT60 CC61 COUT62 01
10
00
11
0
passive
passive
passive
---
---
passive
2
1
0
5
1
ACTIVE passive
passive
---
---
ACTIVE
4
2
0
5
2
ACTIVE ACTIVE
passive
---
---
passive
1
3
0
5
3
passive
ACTIVE
ACTIVE ---
---
passive
2
4
0
5
4
passive
passive
ACTIVE ---
---
ACTIVE
3
1
0
5
5
passive
ACTIVE
passive
---
ACTIVE
2
1
0
5
State
Table 17-4
---
Five-Phase PWM Sequence Table
Output Level Definition (for actual state)
Follower State (for BCM = …)
CC60
COUT61 CC62
COUT60 CC61 COUT62 01
10
00
11
0
passive
passive
passive
passive
---
passive
2
1
0
6
1
ACTIVE passive
passive
passive
---
ACTIVE
5
2
0
6
2
ACTIVE ACTIVE
passive
passive
---
passive
1
3
0
6
3
passive
ACTIVE
ACTIVE passive
---
passive
2
4
0
6
4
passive
passive
ACTIVE ACTIVE
---
passive
3
5
0
6
5
passive
passive
passive
ACTIVE
---
ACTIVE
4
1
0
6
6
passive
ACTIVE
passive
ACTIVE
---
ACTIVE
2
1
0
6
State
Table 17-5
Six-Phase PWM Sequence Table
Output Level Definition (for actual state)
CC60
COUT61 CC62
COUT60 CC61
Follower State (for BCM = …)
COUT62 01
10
00
11
0
passive passive
passive passive
passive passive
1
6
0
7
1
ACTIVE ACTIVE
passive passive
passive passive
6
2
0
7
2
passive ACTIVE
ACTIVE passive
passive passive
1
3
0
7
3
passive passive
ACTIVE ACTIVE
passive passive
2
4
0
7
4
passive passive
passive ACTIVE
ACTIVE passive
3
5
0
7
5
passive passive
passive passive
ACTIVE ACTIVE
4
6
0
7
6
ACTIVE passive
passive passive
passive ACTIVE
5
1
0
7
7
passive ACTIVE
passive ACTIVE
passive ACTIVE
2
1
0
7
Note: To change the rotation direction idle mode must be entered first.
User’s Manual
17-15
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.6.2
Block Commutation Mode
Block commutation mode is a special variation of the multi-channel modes in which the
phase sequence is not controlled internally but rather by the three input signals
CC6POS2…0. The state of the six output signals is derived from the pattern present on
the input signals. Table 17-6 summarizes the possible combinations.
Table 17-6
Block Commutation Sequence Table
Block
Control
Output Level Definition
Commutation Inputs
(for actual state)
Mode (BCM) CC6POS…
0
1
2
CC60
1
0
1
passive passive ACTIVE passive
1
0
0
passive passive ACTIVE ACTIVE passive
passive
1
1
0
passive ACTIVE passive ACTIVE passive
passive
0
1
0
passive ACTIVE passive passive
passive
ACTIVE
0
1
1
ACTIVE passive passive passive
passive
ACTIVE
0
0
1
ACTIVE passive passive passive
ACTIVE passive
1
1
0
ACTIVE passive passive passive
ACTIVE passive
1
0
0
ACTIVE passive passive passive
passive
ACTIVE
1
0
1
passive ACTIVE passive passive
passive
ACTIVE
0
0
1
passive ACTIVE passive ACTIVE passive
passive
0
1
1
passive passive ACTIVE ACTIVE passive
passive
0
1
0
passive passive ACTIVE passive
ACTIVE passive
Rotate Left
Rotate Right
0
0
0
passive passive passive passive
passive
passive
1
1
1
passive passive passive passive
passive
passive
Slow Down
X
X
X
passive passive passive ACTIVE ACTIVE ACTIVE
Idle2)
X
X
X
passive passive passive passive
Rotate Left
Rotate Right
1)
CC61
CC62
COUT60 COUT61 COUT62
ACTIVE passive
passive
passive
1)
If one of these two input signal combinations is detected in rotate left or rotate right mode, bit BCERR is set.
If enabled an emergency interrupt is generated. When these (error) states are encountered, the idle state is
entered immediately.
2)
Idle state is entered when a “wrong follower” is detected (if bit BCEM = ‘1’), or in case of an illegal input pattern
(see note 1). When idle state is entered the BCERR flag is always set.
Idle state can only be left when the BCERR flag is cleared by software.
User’s Manual
17-16
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
In block commutation mode CAPCOM channel 0 is automatically configured for capture
mode. Any signal transition at inputs CC6POS2…0 generates a capture pulse for
CAPCOM channel 0 and sets the interrupt request flag CC0R. A rising edge at output
pin CC60 does not generate an interrupt request in block commutation mode.
The values provide a measurement of the rotation speed of the connected drive. When
evaluating the values captured from the free-running timer T12, the timer must not be
stopped, as this would disturb the operation of block commutation mode.
Note: Modulation of the active phase via T12 is not supported. PWM via T13 is possible
on COUT6x.
The block commutation input signals are available for the full function module
only.
User’s Manual
17-17
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.7
Trap Function
The trap function switches selectable output lines of the CAPCOM6 to predefined levels
simultaneously. The trap function is triggered by an external signal connected to input
CTRAP. This feature provides a very efficient means of protecting external circuitry,
such as power bridges for inverters or motors, which are connected to the CAPCOM6’s
output lines. Register TRCON enables and controls the trap function, register
CC6MCON or P1L provides the output levels during trap state.
Figure 17-11 shows examples for a trap state in edge aligned mode and in center
aligned mode.
Trap Function In Edge Aligned Mode
Notes
Reference Point 1):
Input CTRAP is activated,
the outputs
immediately switch to their
trap level.
T12 + T12OF
Period
Value
Compare
Value
Offset
T12
{
2)
Reference Point 2):
Input CTRAP is inactive,
the outputs switch to their
programmed level
synchronized to a
new timer period.
CCx
Trap State
COUTx
Trap State
1)
CTRAP
Secure Trap State
During trap state the
outputs CC6x and COUT6x
which are selected for T13
modulation are not
modulated with T13’s
output signal but rather
with its initial value.
MCB04114
Trap Function In Center Aligned Mode
T12 + T12OF
Period
Value
Compare
Value
Offset
T12
{
2)
CCx
Trap State
COUTx
Trap State
1)
CTRAP
MCT02606
Figure 17-11 Trap Function
User’s Manual
17-18
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
Entering Trap State
Bit TRPEN generally enables the trigger function of input CTRAP. When enabled, a
falling edge on input CTRAP activates the trap state immediately without any CPU
activity (see Reference Point 1 in Figure 17-11). This event sets the trap flag TRF in
register TRCON (to signal this event to the software) and generates an interrupt request.
An interrupt is generated if the corresponding interrupt node is enabled.
If bit CT12RES in register CTCON is set timer T12 is cleared upon a trap event,
otherwise it continues counting. No more transitions on the output signals will be
generated, however.
Leaving Trap State
After the trap trigger is removed (input CTRAP has been sampled inactive), trap state is
not left immediately, but in a synchronized way (see Reference Point 2 in Figure 17-11),
when timer T12 reaches the value 0000H. This “delay” automatically resumes the
generation of the programmed output signals after a trap event synchronized to the next
timer period. The generation of distorted (truncated) pulses is avoided.
Note: In block commutation mode trap state is exited when timer T13 (not T12) reaches
000H.
Controlling Trap State
The general trap state control signal provides the timing for the trap logic and is valid for
all output signals (see “Trap Trigger” in Figure 17-12).
The trap enable logic determines the effect of the trap state on the individual CAPCOM6
outputs (see “Trap Enable” in Figure 17-12).
In the default case all outputs are switched to the level of the associated port output latch
P1L.x. In this case the trap state level for each output can be predefined independent of
the normal operation of the respective signal (including its initial level).
For each timer separately the standard trap function for its associated outputs can be
disabled by setting bit TT12DIS or TT13DIS, respectively.
For each individual T12 channel (CC60 … COUT62) the respective initial level can be
driven during trap state by setting the associated bit(s) TRENx.
For the T13 output (COUT63) no TREN bit is available, so setting bit TT13DIS disables
the trap function completely for this output.
Note: When controlling inverters or electric motors the standard trap mode (using P1L)
ensures safe operation (all transistors off), so in these cases bits TRENx and
TTxDIS in register TRCON should be written with ‘0’ only.
User’s Manual
17-19
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
Trap Enable
P1L.i
1
MUX
0
i = 0 ... 6
Init Value
XOR
Compare
State
1
MUX
0
CC60
COUT60
CC61
COUT61
CC62
COUT62
COUT63
Sync
Interrupt
Request
T12, T13
'0'
Output Pin
1
MUX
0
TRENx
x = 0 ... 5
'0'
1
MUX
0
TTnDIS
n = 12, 13
Trap Trigger
CTRAP
INV
'0'
1
MUX
0
TRF
TRPEN
MCS04936
Figure 17-12 Trap Control Overview
User’s Manual
17-20
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.8
Register Descriptions
The CAPCOM6 register set provides a number of control, data, and status bits to control
the operation of the two compare timers, the generation of the output signals (up to 7)
and the combination of submodules for multi-channel operation.
Note: The register bits which are available in the full function module only (not in the
reduced version) are marked. This provides an immediate overview of the
available registers and control/status bits in a specific derivative.
Table 17-7 summarizes the available registers. The control registers are described in
detail in the following sections of this chapter. Data registers (such as period or compare
registers) are excluded from the detailed description. Please note that the timer registers
(T12, T13) are not directly accessible.
Table 17-7
CAPCOM6 Register Summary
Name
Description
Address
Read
Sh.L.
T12P
E Timer T12 period register
F030H / 18H
T12OF
E Timer T12 offset register
F034H / 1AH Sh.L.
T13P
E Timer T13 period register
F032H / 19H
Sh.L.
FE36H / 1BH Sh.L.
CMP13
Compare register for compare channel
CC60
Compare register for capture/compare channel 0 FE30H / 18H Reg.
CC61
Compare register for capture/compare channel 1 FE32H / 19H Reg.
CC62
Compare register for capture/compare channel 2 FE34H / 1AH Reg.
CTCON
Compare timer control register
FF30H / 98H
TRCON
Trap enable register
FF34H / 9AH Reg.
CC6MCON
CAPCOM6 mode control register
FF32H / 99H
Reg.
Reg.
CC6MSEL E CAPCOM6 mode select register
F036H / 1BH Reg.
CC6MIC
FF36H / 9BH Reg.
CAPCOM6 interrupt control register
Note: When reading these registers, either the register itself or its shadow latch is
accessed (see description below). This is indicated in column “Read” by
“Reg.” = Register and “Sh.L.” = Shadow latch.
Additionally there are four interrupt node control registers associated with the
CAPCOM6 unit; however, they are not part of the module (see Page 17-33).
User’s Manual
17-21
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
Shadow Latches for Synchronous Update
The timer period, offset, and compare values are written to shadow latches rather than
to the actual registers. Also the initial value bits CCxI/COUTxI in register CC6MCON are
equipped with shadow latches. Thus the values for a new output signal can be
programmed without disturbing the currently generated signal(s). The transfer from the
latches to the registers is enabled by setting the respective shadow latch transfer enable
bit STEx in register CTCON.
If the transfer is enabled the shadow latches are copied to the respective registers the
next time the associated timer reaches the value zero (either being cleared in edge
aligned mode or counting down from 1 in center aligned mode).
When timer T12 is operating in center aligned mode it will also copy the latches (if
enabled) if it reaches the currently programmed period value (counting up).
After the transfer the respective bit STEx is automatically cleared.
Note: While T12/T13 is running, the shadow latch transfer is controlled by bit STE12/13.
While T12/T13 is stopped, the shadow latch transfer is done automatically if bit
CTRES12/13 is set; otherwise those latch values are not transferred.
Note: If a new compare value is written to the shadow latches while T12 is counting up,
the new value must be smaller than the current period value. Otherwise no more
matches will be detected and the output signals will no longer change.
If a compare value is written, while T12 is counting down, any value may be used.
User’s Manual
17-22
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
CTCON
Compare Timer Control Reg.
15
14
13
12
11
CT13 ECT STE CT13 CT13
P 13O 13 RES R
rwh
rw
rwh
rw
rw
SFR (FF30H/98H)
10
9
CT13CLK
rw
8
7
6
Reset Value: 1010H
5
4
3
CT12 CT12
CTM ETRP STE
12 RES R
rw
rw
rwh
rw
2
1
0
CT12CLK
rw
rw
Bit
Function
CTnCLK
Compare Timer Tn Input Clock Select
Selects the input clock for timer T12 or T13 derived from the CPU clock:
fTx = fCPU / 2<CTnCLK>.
000: fTx = fCPU
…
111: fTx = fCPU / 128
CTnR
Compare Timer Tn Run Bit
CTnR starts and stops timer Tn (T12 or T13).
Together with bit CTnRES it controls Tn’s operation.
0:
Timer Tn stops counting. If bit CTnRES = ‘1’ timer Tn is cleared
and the compare outputs are set to their defined idle state.
1:
Timer Tn starts counting from its current value.
CTnRES
Compare Timer Tn Reset Control
0:
No effect on timer Tn when it is stopped.
1:
Timer Tn is cleared when it is stopped and
the compare outputs are set to their defined idle state.
Note: For capture mode (T12 only): Clearing CT12R after a capture
event while CT12RES = ‘1’ will destroy the value stored in the
capture register CC6x (all shadow registers are transparent).
Keep CT12RES = ‘0’ in capture mode.
STE12
Timer T12 Shadow Latch Transfer Enable
0:
Transfer from the shadow latches to the initial value bits, and the
period, compare, and offset registers (T12P, CC6x, T12OF) of
timer T12 is disabled.
1:
Timer T12’s initial value bits, and the period, compare, and offset
registers are loaded from their shadow latches when T12 reaches
0000H (cleared in edge aligned mode, counting down in center
aligned mode).
In center aligned mode the registers are also loaded when T12
reaches the period value.
Note: STE12 is cleared by hardware after the shadow latch transfer.
User’s Manual
17-23
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
Bit
Function
ETRP
Emergency Trap Interrupt Enable
0:
The emergency interrupt for the CAPCOM6 trap signal is disabled.
1:
The emergency interrupt for the CAPCOM6 trap signal is enabled.
CTM
T12 Operating Mode
0:
Edge Aligned Mode: count up.
1:
Center Aligned Mode: count up/down.
STE13
Timer T13 Shadow Latch Transfer Enable
0:
Transfer from the shadow latches to the period and compare
registers (CC62, CMPx) of timer T13 is disabled.
1:
The period and compare registers of timer T13 are loaded from
their shadow latches when T13 reaches the respective period
value.
Note: STE13 is cleared by hardware after the shadow latch transfer.
ECT13O
Enable compare timer T13 output
0:
When ECT13O is cleared and timer T13 is running, signal
COUT63 outputs the corresponding port latch value.
1:
When ECT13O is set and timer T13 is running, timer T13 output
COUT63 is enabled and outputs the PWM signal of the 10-bit
compare channel.
CT13P
Timer T13 Period Flag
The period flag CT13P is set whenever the contents of timer T13 match
the contents of the timer T13 period register. This also generates an
interrupt request.
Bit CT13P must be cleared by software.
User’s Manual
17-24
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
TRCON
Trap Enable Register
15
14
13
12
SFR (FF34H/9AH)
11
10
9
8
TRP TRF TR TR TR TR TR TR
EN5 EN4 EN3 EN2 EN1 EN0
EN
rw
rwh
rw
rw
rw
rw
rw
rw
Reset Value: 0000H
7
6
5
4
3
2
-
-
-
-
-
-
-
-
-
-
-
-
1
0
TT13 TT12
DIS DIS
rw
rw
Bit
Function
TT12DIS
Timer T12 Trap Disable Bit
0:
Standard trap levels for timer T12 controlled outputs (P1L)
1:
Trap level is initial value for those timer T12 controlled outputs
enabled by bits TRENx
TT13DIS
Timer T13 Trap Disable Bit
0:
Standard trap level for timer T13 controlled output (P1L)
1:
Trap function for timer T13 controlled output is disabled
TRENx
Trap Enable for Output Pins
0:
Trap function for the respective output is disabled
1:
Trap level is initial value for the respective output, if the standard
trap level (from P1L) is disabled by bot TT12DIS = ‘1’
TRF
Trap Flag
TRF is set by hardware if the trap function is enabled (TRPEN = 1) and
CTRAP becomes active (low). If enabled, an interrupt is generated when
TRF is set.
TRF must be cleared by software.
TRPEN
External CTRAP Trap Function Enable Bit
0:
External trap input CTRAP is disabled (default after reset).
1:
External trap input CTRAP is enabled.
Note: For applications driving inverters or electric motors the standard trap mode using
P1L provides maximum safety. It is therefore recommended to keep bits TRENx
and TT12DIS cleared (only write ‘0’ to those bit locations).
User’s Manual
17-25
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
CC6MCON
CAPCOM6 Mode Ctrl. Reg.
15
BC
POL
BC
EM
rw
14
13
MPWM
rw
12
11
SFR (FF32H/99H)
10
EB BC BC
CE ERR EN
rw
rwh
rw
9
8
BCM
rw
7
6
Reset Value: 00FFH
5
4
3
2
1
0
COUT COUT COUT CC2I COUT CC1I COUT CC0I
0I
1I
3I
XI
2I
rw
rw
rw
rw
rw
rw
rw
rw
Bit
Function
CCnI
Compare Output CC6n Initial Value (n = 0 … 2)
The compare output CC6n drives the value of CCnI when the compare
timer T12 is not running. CCnI represents the passive output level for an
enabled compare channel.
Note: The initial values are valid only for capture/compare outputs
which are enabled for compare mode operation (compare output).
COUTnI
Compare Output COUT6n Initial Value (n = 0 … 2)
The compare output COUT6n drives the value of COUTnI when the
compare timer T12 is not running. COUTnI represents the passive
output level for an enabled compare channel.
Note: The initial values are valid only for capture/compare outputs
which are enabled for compare mode operation (compare output).
COUTXI
COUT6n Inversion Control
0:
T13’s output signal is directly connected to compare outputs
COUT6n in burst or multi-channel mode (n = 0 … 2).
1:
T13’s output signal is inverted and then connected to compare
outputs COUT6n in burst or multi-channel mode (n = 0 … 2).
COUT3I
Compare Output COUT63 Initial Value
This bit defines the initial logic state of the output COUT63 before timer
T13 is started the first time. Further, COUT3I defines the logic state of
COUT63 when bit ECT13O is reset (COUT63 disabled).
BCM
Multi-channel PWM Mode Output Pattern Selection
This bitfield selects the output signal pattern in all multi-channel PWM
modes (also refer to bitfield MPWM).
00: Idle mode.
01: Rotate right mode.
10: Rotate left mode.
11: Slow down mode.
User’s Manual
17-26
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
Bit
Function
BCEN
Block Commutation Enable
0:
The multi-channel PWM modes of the 16-bit capture/compare
channels (selected by bitfield MPWM) are disabled.
1:
The multi-channel PWM modes are enabled.
Note: Before bit BCEN is set, all required PWM compare outputs should
be programmed to operate as compare outputs by writing to
register CC6MSEL.
BCERR
Block Commutation Mode Error Flag
0:
No error condition.
1:
An error condition in rotate right or rotate left mode has occurred:
- After a transition at CC6POSx all CC6POSx inputs are at high or
low level.
- A “wrong follower” condition has occurred (see description of bit
BCEM).
If the block commutation interrupt is enabled (EBCE = ‘1’) a CAPCOM6
emergency interrupt will also be generated.
BCERR must be cleared by software.
EBCE
Enable Block Commutation Mode Error Interrupt
0:
Block commutation mode error does not generate an interrupt.
1:
The emergency interrupt is activated for a block commutation
mode error.
Refer to the description of bits BCERR and BCEM.
MPWM
Multi-channel PWM Mode Selection
This bitfield selects the output signal pattern in all multi-channel PWM
modes (also refer to bitfield BCM).
00: Three-phase block commutation mode.
01: Four-phase multi-channel PWM mode.
10: Five-phase multi-channel PWM mode.
11: Six-phase multi-channel PWM mode.
User’s Manual
17-27
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
Bit
Function
BCPOL
Machine polarity (Valid only in multi-channel PWM mode)
0:
Only the COUT6n outputs are switched to the timer T13 output
signal during the active phase in multi-channel PWM mode.
CMSELn3 must be set for that functionality.
1:
All enabled compare outputs COUT6n and CC6n are switched to
the timer T13 output signal during their active phase in multichannel PWM mode.
Error mode select bit (Valid only in block commutation mode)
0:
A “wrong follower” condition is not notified as an error.
1:
A “wrong follower” condition in rotate right or rotate left mode sets
flag BCERR if EBCE is set.
BCEM
Note: When a multi-channel PWM mode is initiated the first time after reset, CC6MCON
must be written twice: The first write operation is with bit BCEN cleared and all
other bits set/cleared as required (BCM must be ‘00’ for idle mode), the second
write operation has the same CC6MCON bit pattern as the first write operation but
with BCEN set. After this second CC6MCON write operation, timer T12 can be
started (setting CT12R in CTCON) and thereafter BCM can be put into a mode
other than the idle mode.
User’s Manual
17-28
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
CC6MSEL
CAPCOM6 Mode Select Reg.
15
14
13
12
ES
MC
NM
CS
-
-
rw
rw
-
-
11
CM
SEL
23
rw
10
ESFR (F036H/1BH)
9
CMSEL2
rw
8
7
CM
SEL
13
rw
6
Reset Value: 0000H
5
CMSEL1
rw
4
3
CM
SEL
03
rw
2
1
0
CMSEL0
rw
Bit
Function
CMSELn
Capture/Compare Mode Selection
These bitfields select/enable the operating mode and the output/input
pin configuration of the 16-bit capture/compare channels. Each channel
can be programmed individually either for compare or capture operation.
000:
001:
010:
011:
Compare outputs disabled, CC6n/COUT6n can be used for IO.
Compare output on pin CC6n, COUT6n can be used for IO.
Compare output on pin COUT6n, CC6n can be used for IO.
Compare output on pins COUT6n and CC6n.
100:
101:
110:
111:
Capture mode, not triggered by CC6n. COUT6n is IO.
Capture mode, trigg’d by a rising edge on CC6n. COUT6n is IO.
Capture mode, trigg’d by a falling edge on CC6n. COUT6n is IO.
Capture mode, trigg’d by any transition on CC6n. COUT6n is IO.
CMSELn3
COUT6n Control by Timer T13 in Compare Mode
This bit determines if the output COUT6n is modulated during its active
phase (defined via register CC6MCON) by the output signal of the 10-bit
compare channel, typically a higher frequency signal.
0:
COUT6n drives its active level.
1:
COUT6n is modulated by the output signal of the 10-bit compare
channel.
NMCS
Next Multi-Channel PWM State (Valid when ESMC = ‘1’)
0:
Idle.
1:
Select the next follower state in the 4/5/6-phase multi-channel
PWM modes.
NMCS is reset by hardware in the next clock cycle after it has been set.
ESMC
Enable Software Controlled Multi-Channel PWM Modes
Defines the follower state selection in the 4/5/6-phase multi-channel
PWM modes.
0:
Follower state selection controlled by compare timer T12.
1:
Follower state selection controlled by bit NMCS (software control).
User’s Manual
17-29
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
CC6MIC
CAPCOM6 Interrupt Ctrl. Reg.
15
14
13
12
11
10
SFR (FF36H/9BH)
9
8
CT12 CT12 CC2 CC2 CC1 CC1 CC0 CC0
FP FC
F
R
F
R
F
R
rw
rw
rw
rw
rw
rw
rw
rw
7
6
EC
TP
EC
TC
rw
rw
Reset Value: 0000H
5
4
3
2
1
0
CC2 CC2 CC1 CC1 CC0 CC0
FEN REN FEN REN FEN REN
rw
rw
rw
Bit
Function
CCnREN
Capture/Compare Rising Edge Interrupt Enable
0:
Rising edge interrupt disabled.
1:
An interrupt from request flag CCnR is enabled.
CCnFEN
Capture/Compare Falling Edge Interrupt Enable
0:
Falling edge interrupt disabled.
1:
An interrupt from request flag CCnF is enabled.
ECTC
Enable Timer T12 Count Direction Change Interrupt
0:
Count direction change interrupt disabled.
1:
An interrupt from request flag CT12FC is enabled.
rw
rw
rw
Note: No effect in edge aligned mode.
ECTP
Enable Timer T12 Period Interrupt
0:
Period interrupt disabled.
1:
An interrupt from request flag CT12FP is enabled.
CCnR
Capture/Compare Rising Edge Interrupt Flag
0:
Idle.
1:
The interrupt request flag is set as follows:
- Capture mode: upon a rising edge at the corresponding
CC6n input
- Compare mode: when T12 matches compare register CC6n
while counting up (in both operating modes of timer T12).
CCnF
Capture/Compare Falling Edge Interrupt Flag
0:
Idle.
1:
The interrupt request flag is set as follows:
- Capture mode: upon a falling edge at the corresponding
CC6n input
- Compare mode: when T12 matches compare register CC6n
while counting down (in center aligned mode, timer T12 only).
User’s Manual
17-30
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
Bit
Function
CT12FC
Timer T12 Count Direction Change Flag
0:
Idle.
1:
An interrupt request is generated when T12 matches 0000H
(counting down in center aligned mode) and changes to counting
up. There is no effect in edge aligned mode.
CT12FP
Timer T12 Period Flag
0:
Idle.
1:
An interrupt request is generated when T12 matches the period
value.
Note: All CAPCOM6 interrupt request bits in register CC6MIC must be cleared by
software.
User’s Manual
17-31
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
17.9
The CAPCOM6 Interrupt Structure
Figure 17-13 summarizes the CAPCOM6’s interrupt sources and the related status and
control flags, and shows the association with the four CAPCOM6 interrupt nodes.
CC60
Input
CAPCOM6 Intr. Contr.
CC0R
CC0REN
CC0F
CC0FEN
Reg. CC60
Compare
Event 1)
CC61
Input
CC6CIC
>1
CC1R
CC1REN
IR
IE
CC1F
CC1FEN
Reg. CC61
Compare
Event
CC62
Input
CC2R
CC2REN
CC2F
CC2FEN
Reg. CC62
Compare
Event
CC6EIC
>1
TRF
Emergency
Interrupt
ETRP
IR
IE
BCERR
EBCE
T12IC
>1
CT12FP
Timer T12
Events
ECTP
IR
IE
CT12FC
ECTC
Timer T13
Period
CT13P
T13IC
IR
IE
1)
Internal capture event in case of block commutation mode. Use only CC0R in this case.
MCS04935
Figure 17-13 CAPCOM6 Interrupt Structure
User’s Manual
17-32
V1.0, 2002-02
C164CM/C164SM
Derivatives
Capture/Compare Unit CAPCOM6
Interrupt Node Control Registers
ESFR (F190H/C8H)
T12IC
15
14
13
12
11
10
9
8
7
6
Reset Value: 0000H
5
T12 T12
IR
IE
-
-
-
-
-
-
T13IC
15
-
-
rwh
14
13
12
11
10
9
8
7
6
-
-
-
-
-
14
-
-
rwh
12
11
10
9
8
7
Reset Value: 0000H
5
-
-
-
-
-
CC6CIC
15
14
-
-
rwh
3
12
11
10
9
8
7
6
-
-
-
-
-
-
-
rwh
rw
1
0
GLVL
rw
rw
5
4
3
2
1
0
ILVL
GLVL
rw
rw
ESFR (F17EH/BFH)
13
2
ILVL
rw
CC6 CC6
IR
EI
-
4
Reset Value: 0000H
CC6 CC6
EIR EIE
-
0
rw
rw
6
1
rw
ESFR (F188H/C4H)
13
2
GLVL
ESFR (F198H/CCH)
CC6EIC
15
3
ILVL
rw
T13 T13
IR
IE
-
4
Reset Value: 0000H
5
4
3
2
1
0
ILVL
GLVL
rw
rw
Note: Please refer to the general Interrupt Control Register description for an
explanation of the control fields.
User’s Manual
17-33
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
18
Analog/Digital Converter
The C164CM provides an Analog/Digital Converter (ADC) with 10-bit resolution and a
sample & hold circuit on-chip. A multiplexer selects up to 8 analog input channels
(alternate functions of Port 5) either via software (fixed channel modes) or automatically
(auto scan modes).
To fulfill most requirements of embedded control applications, the ADC supports the
following conversion modes:
• Fixed Channel Single Conversion
produces just one result from the selected channel
• Fixed Channel Continuous Conversion
repeatedly converts the selected channel
• Auto Scan Single Conversion
produces one result from each of a selected group of channels
• Auto Scan Continuous Conversion
repeatedly converts the selected group of channels
• Wait for ADDAT Read Mode
start a conversion automatically when the previous result was read
• Channel Injection Mode
insert the conversion of a specific channel into a group conversion (auto scan)
A set of SFRs and port pins provide access to control functions and results of the ADC.
Ports & Direction Control
Alternate Functions
Data Registers
P5
ADDAT
P5DIDIS
ADDAT2
P5
P5DIDIS
ADDAT
ADDAT2
Control Registers
Interrupt Control
ADCON
ADCIC
E
ADEIC
ADCON
ADCIC
Port 5 Analog Input Port:
AN0/P5.0 ... AN7/P5.7
Port 5 Digital Input Disable Register
A/D Converter Result Register
A/D Converter Channel Injection
Result Register
ADEIC
A/D Converter Control Register
A/D Converter Interrupt Control
Register (End of Conversion)
A/D Converter Interrupt
Control Register
(Overrun Error / Channel Injection)
MCA05090
Figure 18-1 SFRs and Port Pins Associated with the A/D Converter
User’s Manual
18-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
The external analog reference voltages VAREF and VAGND are fixed. The separate
supply for the ADC reduces the interference with other digital signals.
The sample time and the conversion time are programmable, so the ADC can be
adjusted to the internal resistances of the analog sources and/or the analog reference
voltage supply.
ADCON
Conversion
Control
AN0
MUX
S+H
10-Bit
Converter
AN7
VAREF
VAGND
ADCIR
Interrupt
Requests
ADEIR
Result Reg. ADDAT
Result Reg. ADDAT2
MCA05092
Figure 18-2 Analog/Digital Converter Block Diagram
User’s Manual
18-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
18.1
Mode Selection and Operation
The analog input channels AN7 … AN0 are alternate functions of Port 5 which is an
input-only port. The Port 5 lines may be used as either analog or digital inputs. For pins
to be used as analog inputs, it is recommended to disable the digital input stage via
register P5DIDIS. This avoids undesired cross currents and switching noise when the
(analog) input signal level is between VIL and VIH.
The functions of the A/D converter are controlled by the bit-addressable A/D Converter
Control Register ADCON. Its bitfields specify the analog channel to be acted upon, the
conversion mode, and also reflect the status of the converter.
ADCON
ADC Control Register
15
14
13
12
ADCTC
ADSTC
rw
rw
SFR (FFA0H/D0H)
11
10
AD AD
CRQ CIN
rwh
rw
9
8
7
AD AD AD
WR BSY ST
rw
rwh
rwh
6
Reset Value: 0000H
5
4
1
ADM
ADCH
-
rw
rw
Function
ADCH
ADC Analog Channel Input Selection
Selects the (first) ADC channel to be converted.
ADM
ADC Mode Selection
00: Fixed Channel Single Conversion
01: Fixed Channel Continuous Conversion
10: Auto Scan Single Conversion
11: Auto Scan Continuous Conversion
ADST
ADC Start Bit
0:
Stop a running conversion
1:
Start conversion(s)
ADBSY
ADC Busy Flag
0:
ADC is idle
1:
A conversion is active
ADWR
ADC Wait for Read Control
ADCIN
ADC Channel Injection Enable
ADCRQ
ADC Channel Injection Request Flag
18-3
2
-
Bit
User’s Manual
3
0
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
Bit
Function
ADSTC
ADC Sample Time Control (Defines the ADC sample time in a certain range)
00: tBC × 8
01: tBC × 16
10: tBC × 32
11: tBC × 64
ADCTC
ADC Conversion Time Control (Defines the ADC basic conversion clock fBC)
00: fBC = fCPU / 4
01: fBC = fCPU / 2
10: fBC = fCPU / 16
11: fBC = fCPU / 8
Bitfield ADCH specifies the analog input channel to be converted (first channel of a
conversion sequence in auto scan modes). Bitfield ADM selects the operating mode of
the A/D converter. A conversion (or a sequence) is then started by setting bit ADST.
Clearing ADST stops the A/D converter after a specified operation as determined by the
selected operating mode.
The busy flag (read-only) ADBSY is set as long as a conversion is in progress.
The result of a conversion is stored in the result register ADDAT, or in register ADDAT2
for an injected conversion.
Note: Bitfield CHNR of register ADDAT is loaded by the ADC to indicate the channel to
which the result refers.
Bitfield CHNR of register ADDAT2 is loaded by the CPU to select the analog
channel to be injected.
User’s Manual
18-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
ADDAT
ADC Result Register
15
14
13
12
SFR (FEA0H/50H)
11
10
CHNR
-
-
ADRES
rwh
-
-
rwh
ADDAT2
ADC Chan. Inj. Result Reg.
15
14
13
12
9
8
7
6
Reset Value: 0000H
5
4
ESFR (F0A0H/50H)
9
8
7
6
3
2
10
CHNR
-
-
ADRES
rw
-
-
rwh
5
4
3
2
Bit
Function
ADRES
A/D Conversion Result
The 10-bit digital result of the most recent conversion.
CHNR
Channel Number (identifies the converted analog channel)
18-5
0
Reset Value: 0000H
11
User’s Manual
1
1
0
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
A conversion is started by setting bit ADST = ‘1’. The busy flag ADBSY will be set. Then
the converter selects and samples the input channel specified by the channel selection
field ADCH in register ADCON. The sampled level will then be held internally during the
conversion. When the conversion of this channel is complete, the 10-bit result and the
number of the converted channel are transferred into the result register ADDAT and the
interrupt request flag ADCIR is set. The conversion result is placed into bitfield ADRES
of register ADDAT.
If bit ADST is reset via software while a conversion is in progress, the A/D converter will
stop after the current conversion (fixed channel modes) or after the current conversion
sequence (auto scan modes).
Setting bit ADST while a conversion is running will abort this conversion and start a new
conversion with the parameters specified in ADCON.
Note: Abort and restart are triggered by bit ADST changing from ‘0’ to ‘1’; thus, ADST
must be ‘0’ before being set.
While a conversion is in progress, the mode selection field ADM and the channel
selection field ADCH may be changed. ADM will be evaluated after the current
conversion. ADCH will be evaluated after the current conversion (fixed channel modes)
or after the current conversion sequence (auto scan modes).
Fixed Channel Conversion Modes
These modes are selected by programming the mode selection bitfield ADM in register
ADCON to ‘00B’ (single conversion) or to ‘01B’ (continuous conversion). After starting the
converter through bit ADST, the busy flag ADBSY will be set and the channel specified
in bit field ADCH will be converted. After the conversion is complete, the interrupt request
flag ADCIR will be set.
In Single Conversion Mode, the converter will automatically stop and reset bits ADBSY
and ADST.
In Continuous Conversion Mode, the converter will automatically start a new
conversion of the channel specified in ADCH. ADCIR will be set after each completed
conversion.
When bit ADST is reset by software while a conversion is in progress, the converter will
complete the current conversion and then stop and reset bit ADBSY.
User’s Manual
18-6
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
Auto Scan Conversion Modes
These modes are selected by programming the mode selection field ADM in register
ADCON to ‘10B’ (single conversion) or to ‘11B’ (continuous conversion). Auto Scan
modes automatically convert a sequence of analog channels, beginning with the channel
specified in bit field ADCH and ending with channel 0, without requiring software to
change the channel number.
After starting the converter through bit ADST, the busy flag ADBSY will be set and the
channel specified in bit field ADCH will be converted. After the conversion is complete,
the interrupt request flag ADCIR will be set and the converter will automatically start a
new conversion of the next lower channel. ADCIR will be set after each completed
conversion. The current sequence is complete after conversion of channel 0.
In Single Conversion Mode, the converter will automatically stop and reset bits ADBSY
and ADST.
In Continuous Conversion Mode, the converter will automatically start a new
sequence beginning with the conversion of the channel specified in ADCH.
When bit ADST is reset by software while a conversion is in progress, the converter will
complete the current sequence (including conversion of channel 0) and then stop and
reset bit ADBSY.
#3
Conversion
of Channel..
Write ADDAT
ADDAT Full
Generate Interrupt
Request
Read of ADDAT;
Result of Channel:
#x
#x
#2
#3
#1
#0
#2
#1
#2
#3
#3
#0
ADDAT Full;
Channnel 0
# 1 Result Lost
#2
#3
#3
Overrun Error
Interrupt Request
MCA02241
Figure 18-3 Auto Scan Conversion Mode Example
User’s Manual
18-7
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
Wait for ADDAT Read Mode
In ADC default mode, if a previous conversion result has not been read out of register
ADDAT by the time a new conversion is complete, the previous result in register ADDAT
is lost because it is overwritten by the new value, and the A/D overrun error interrupt
request flag ADEIR will be set.
To avoid error interrupts and the loss of conversion results (especially when using
continuous conversion modes), the ADC can be switched to “Wait for ADDAT Read
Mode” by setting bit ADWR in register ADCON.
If the value in ADDAT has not been read by the time the current conversion is complete,
the new result is stored in a temporary buffer and the next conversion is suspended
(ADST and ADBSY will remain set in the meantime, but no end-of-conversion interrupt
will be generated). After reading the previous value from ADDAT, the temporary buffer
is copied into ADDAT (generating an ADCIR interrupt) and the suspended conversion is
restarted. This mechanism applies to both single and continuous conversion modes.
Note: In standard mode, continuous conversions are executed at a fixed rate
(determined by the conversion time). In “Wait for ADDAT Read Mode” there may
be delays due to suspended conversions. However, this affects the conversions
only if the CPU (or PEC) cannot keep up with the conversion rate.
#3
#2
#1
wait
#0
#3
Conversion
of Channel..
Write ADDAT
ADDAT Full
Temp-Latch Full
#x
#2
#3
#0
#3
1
Generate Interrupt
Request
Read of ADDAT;
Result of Channel:
#1
Hold Result in
Temp-Latch
#x
#3
#2
#1
#0
MCA01970
Figure 18-4 Wait for Read Mode Example
User’s Manual
18-8
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
Channel Injection Mode
Channel Injection Mode allows conversion of a specific analog channel (also while the
ADC is running in a continuous or auto scan mode) without changing the current
operating mode. After the conversion of this specific channel, the ADC continues with
the original operating mode.
Channel Injection Mode is enabled by setting bit ADCIN in register ADCON and requires
the Wait for ADDAT Read Mode (ADWR = ‘1’). The channel to be converted in this mode
is specified in bitfield CHNR of register ADDAT2.
Note: Bitfield CHNR in ADDAT2 is not modified by the A/D converter, only the ADRES
bit field is modified. Because the channel number for an injected conversion is not
buffered, bit field CHNR of ADDAT2 must never be modified during the sample
phase of an injected conversion; otherwise, the input multiplexer will switch to the
new channel. It is recommended to change the channel number only when no
injected conversion is running.
#x
# x-1
Conversion
of Channel..
Write ADDAT; # x+1
ADDAT Full
Read ADDAT
Injected
Conversion
of Channel # y
#x
# x+1
# x-2
# x-1
#x
# x-4
# x-3
# x-2
# x-1
# x-3
# x-2
# ...
# x-4
# x-3
# x-4
#y
Channel Injection
Request
Write ADDAT2
ADDAT2 Full
Int. Request
ADEINT
Read ADDAT2
MCA01971
Figure 18-5 Channel Injection Example
User’s Manual
18-9
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
A channel injection can be triggered in two ways:
• Set the Channel Injection Request bit ADCRQ via software
• Initiate a compare or a capture event of Capture/Compare register CC27 of the
CAPCOM2 unit; this also sets bit ADCRQ.
The second method triggers a channel injection at a specific time; either on the
occurrence of a predefined count value of the CAPCOM timers or on a capture event of
register CC27. This can be either the positive, the negative, or both the positive and the
negative edges of an external signal. Additionally, this option allows the time at which
this signal occurs to be recorded.
Note: The channel injection request bit ADCRQ will be set on any interrupt request of
CAPCOM2 channel CC27, regardless of whether or not the channel injection
mode is enabled. It is recommended to always clear bit ADCRQ before enabling
the channel injection mode.
After the completion of the current conversion (if any is in progress), the converter will
start (inject) the conversion of the specified channel. When the conversion of this
channel is complete, the result will be placed into the alternate result register ADDAT2.
A Channel Injection Complete Interrupt request will also be generated which uses the
interrupt request flag ADEIR (the Wait for ADDAT Read Mode is required for this
reason).
Note: If the temporary data register used in Wait for ADDAT Read Mode is full, the next
conversion (either standard or injected) will be suspended. The temporary register
can hold data for ADDAT (from a standard conversion) or for ADDAT2 (from an
injected conversion).
User’s Manual
18-10
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
#x
# x-1
# x-2
Conversion
of Channel..
Write ADDAT # x+1
ADDAT Full
# x+1
Read ADDAT
Injected
Conversion
of Channel y
#x
Wait until
ADDAT2 is
read
# x-1
#x
Channel Injection
Request
# x-3
# x-2
# x-1
# ...
# x-3
# x-3
# x-2
Write ADDAT2
#z
#y
ADDAT2 Full
Int. Request
ADEINT
#z
Read ADDAT2
#y
Temp-Latch
Full
# x-1
#x
# x-3
# x-2
# ...
Conversion
of Channel..
Write ADDAT # x+1
ADDAT Full
Read ADDAT
# x-1
#x
#x
# x+1
# x-2
# x-3
# x-2
# x-1
# x-3
Temp-Latch
Full
#y
Channel Injection
Request
ADDAT2 Full
Wait until
ADDAT2 is
read
Write ADDAT2
Int. Request
ADEINT
#y
Read ADDAT2
MCA01972
Figure 18-6 Channel Injection Example with Wait for Read
User’s Manual
18-11
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
Arbitration of Conversions
Conversion requests activated while the ADC is idle immediately trigger the requested
conversion. If a conversion is requested while another conversion is already in progress,
the operation of the A/D converter depends on the type of conversions involved (either
standard or injected).
Note: A conversion request is activated if the respective control bit (ADST or ADCRQ)
is toggled from ‘0’ to ‘1’, i.e. the bit must have been zero before being set.
Table 18-1 summarizes ADC operation in the situations possible.
Table 18-1
Conversion Arbitration
Conversion
in Progress Standard
New Requested Conversion
Injected
Standard
Abort running conversion,
and start requested new
conversion.
Complete running conversion,
start requested conversion after that.
Injected
Complete running conversion,
start requested conversion after
that.
Complete running conversion,
start requested conversion after that.
Bit ADCRQ will be ‘0’ for the second
conversion, however.
User’s Manual
18-12
V1.0, 2002-02
C164CM/C164SM
Derivatives
Analog/Digital Converter
18.2
Conversion Timing Control
When a conversion is started, the capacitances of the converter are loaded first, via the
respective analog input pin to the current analog input voltage. The time to load the
capacitances is referred to as sample time. Next, the sampled voltage is converted to a
digital value in successive steps corresponding to the resolution of the ADC. During
these phases (except for the sample time), the internal capacitances are repeatedly
charged and discharged via pins VAREF and VAGND.
The amount of current to be drawn from the sources for sampling and changing charges
depends on the time that each respective step takes, because the capacitors must reach
their final voltage level within the given time, at least within a certain approximation. The
maximum current, however, that a source can deliver, depends on its internal resistance.
The time required by the two sampling and converting phases during conversion can be
programmed to be within a certain range in the C164CM relative to the CPU clock. The
absolute time consumed by the different conversion steps is therefore, independent from
the general speed of the controller. This allows the A/D converter of the C164CM to be
adjusted to the properties of the system:
Fast Conversion can be achieved by programming the respective times to their
absolute possible minimum. This is preferred for scanning high frequency signals, but
the internal resistance of the analog source and analog supply must be sufficiently low.
High Internal Resistance can be achieved by programming the respective times to a
higher value, or to the possible maximum. This is preferred when using analog sources
and an analog supply with a high internal resistance in order to keep the current as low
as possible. The conversion rate in this case may be considerably lower, however.
The conversion time is programmed via the upper two bits of register ADCON. Bitfield
ADCTC (conversion time control) selects the basic conversion clock (fBC), used for the
operation of the A/D converter. The sample time is derived from this conversion clock.
Table 18-2 lists the possible combinations. The timings refer to CPU clock cycles where
tCPU = 1 / fCPU.
The limit values for fBC (see data sheet) must not be exceeded when selecting ADCTC
and fCPU.
Table 18-2
ADC Conversion Timing Control
ADCON.15|14
(ADCTC)
A/D Converter
Basic Clock fBC
ADCON.13|12
(ADSTC)
Sample Time tS
00
fCPU / 4
fCPU / 2
fCPU / 16
fCPU / 8
00
tBC × 8
tBC × 16
tBC × 32
tBC × 64
01
10
11
User’s Manual
01
10
11
18-13
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Derivatives
Analog/Digital Converter
The time for a complete conversion includes the sample time tS, the actual conversion
and the time required to transfer the digital value to the result register (2 tCPU) as shown
in the example below.
Note: The non-linear decoding of bit field ADCTC provides compatibility with 80C166
designs for the default value (‘00’ after reset).
Converter Timing Example
Assumptions:
Basic clock
Sample time
Conversion time
fCPU = 25 MHz (i.e. tCPU = 40 ns), ADCTC = ‘00’, ADSTC = ‘00’.
fBC = fCPU / 4 = 6.25 MHz, i.e. tBC = 160 ns.
tS = tBC × 8 = 1280 ns.
tC = tS + 40 tBC + 2 tCPU = (1280 + 6400 + 80) ns = 7.76 µs.
Note: For the exact specification please refer to the data sheet of the selected derivative.
User’s Manual
18-14
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Derivatives
Analog/Digital Converter
18.3
A/D Converter Interrupt Control
At the end of each conversion, the interrupt request flag ADCIR in interrupt control
register ADCIC is set. This end-of-conversion interrupt request may cause an interrupt
to vector ADCINT, or it may trigger a PEC data transfer which reads the conversion result
from register ADDAT and stores it into a table in the internal RAM for later evaluation, for
example.
The interrupt request flag ADEIR in register ADEIC will be set if either a conversion result
overwrites a previous value in register ADDAT (error interrupt in standard mode), or if
the result of an injected conversion has been stored into ADDAT2 (end-of-injectedconversion interrupt). This interrupt request may be used to cause an interrupt to vector
ADEINT, or it may trigger a PEC data transfer.
ADCIC
ADC Conversion Intr.Ctrl.Reg. SFR (FF98H/CCH)
15
14
13
12
11
10
9
8
-
-
-
-
-
ADEIC
ADC Error Intr.Ctrl.Reg.
15
14
13
12
11
-
-
-
-
-
5
rwh
10
9
8
7
6
-
-
-
rwh
rw
3
2
1
0
ILVL
GLVL
rw
rw
rw
ADE ADE
IR
IE
-
4
SFR (FF9AH/CDH)
-
6
ADC ADC
IR
IE
-
7
Reset Value: - - 00H
Reset Value: - - 00H
5
4
3
2
1
0
ILVL
GLVL
rw
rw
Note: Please refer to the general Interrupt Control Register description for an
explanation of the control fields.
User’s Manual
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Derivatives
On-Chip CAN Interface
19
On-Chip CAN Interface
The Controller Area Network (CAN) bus and its associated protocol allow highly efficient
communication among a number of stations connected to this bus.
Efficiency in this context refers to:
•
•
•
•
Transfer speed (Data rates of up to 1 Mbit/s can be achieved)
Data integrity (The CAN protocol provides several means of error checking)
Host processor unloading (The controller handles most of the tasks autonomously)
Flexible and powerful message passing (The extended CAN protocol is supported)
The integrated CAN module handles the completely autonomous transmission and
reception of CAN frames in accordance with the CAN specification V2.0 part B (active).
Because of this, the on-chip CAN module can receive and transmit:
• Standard frames with 11-bit identifiers, as well as
• Extended frames with 29-bit identifiers.
Note: The CAN module is an XBUS peripheral and, therefore, requires bit XPEN in
register SYSCON to be set in order to be operable.
Core Registers
SYSCON
SYSCON3
E
DP8
E
ODP8
SYSCON
SYSCON3
DP8
ODP8
XP0IC
Control Registers
(within each module)
Object Registers
(within each module)
CSR
X
MCRn
X
PCIR
X
UARn
X
BTR
X
LARn
X
GMS
X
Data
X
U/LGML
X
U/LMLM
X
System Configuration Register
Peripheral Management Control Reg.
Port 8 Direction Control Register
Port 8 Open Drain Control Register
CAN1 Interrupt Control Register
CSR
PCIR
BTR
GMS
U/LGML
U/LMLM
MCRn
U/LARn
Interrupt Control
XP0IC
E
Control / Status Register
Port Control / Interrupt Register
Bit Timing Register
Global Mask Short
Global Mask Long
Last Message Mask
Configuration Register of Message n
Arbitration Register of Message n
MCA05126
Figure 19-1 Registers Associated with the CAN Module
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Derivatives
On-Chip CAN Interface
Bit timing is derived from the XCLK and is programmable up to a data rate of 1 Mbit/s.
The minimum CPU clock frequency to achieve 1 Mbit/s is fCPU ≥ 8/16 MHz, depending
on the activation of the CAN module’s clock prescaler.
The CAN module uses two pins of Port 8 to interface to a bus transceiver.
The CAN module provides Full CAN functionality for up to 15 full-sized message objects
(8 data bytes each). Message object 15 may be configured for Basic CAN functionality
with a double-buffered receive object.
The Full CAN and Basic CAN modes provide separate masks for acceptance filtering to
accept a number of identifiers in Full CAN mode and disregard a number of identifiers in
Basic CAN mode.
All message objects can be updated independent of the others during operation of the
module and are equipped with buffers for the maximum message length of 8 Bytes.
19.1
Functional Blocks of the CAN Module
The CAN module combines several functional blocks (see Figure 19-2) that work in
parallel and contribute to the controller’s performance. These units and the functions
they provide are described below.
Each of the message objects has a unique identifier and its own set of control and status
bits. Each object can be configured with its direction as either transmit or receive, except
for the last message which is only a double receive buffer with a special mask register.
An object with its direction set as transmit can be configured to be automatically sent
whenever a remote frame with a matching identifier (taking into account the respective
global mask register) is received over the CAN bus. By requesting the transmission of a
message with the direction set as receive, a remote frame can be sent to request that
the appropriate object be sent by some other node. Each object has separate transmit
and receive interrupts and status bits, giving the CPU full flexibility in detecting when a
remote/data frame has been sent or received.
For general purposes, two masks for acceptance filtering can be programmed, one for
identifiers of 11 bits and one for identifiers of 29 bits. However, the CPU must configure
bit XTD (Normal or Extended Frame Identifier) for each valid message to determine
whether a standard or extended frame will be accepted.
The last message object has its own programmable mask for acceptance filtering,
allowing a large number of infrequent objects to be handled by the system.
The object layer architecture of the CAN controller is designed to be as regular and
orthogonal as possible. This makes it easy to use.
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Derivatives
On-Chip CAN Interface
CAN_TxD
CAN_RxD
BTL - Configuration
BTL
CRC
Timing
Generator
Tx/Rx Shift Register
Messages
Messages
Handlers
Clocks
(to all)
Intelligent Memory
Control
Interrupt
Register
Status +
Control
BSP
Status
Register
EML
to XBUS
MCB04391
Figure 19-2 CAN Controller Block Diagram
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Derivatives
On-Chip CAN Interface
Tx/Rx Shift Register
The Transmit/Receive Shift Register holds the destuffed bit stream from the bus line to
allow parallel access to the entire data frame or remote frame for the acceptance match
test and parallel transfer of the frame to and from the Intelligent Memory.
Bit Stream Processor
The Bit Stream Processor (BSP) is a sequencer controlling the sequential data stream
between the Tx/Rx Shift Register, the CRC Register, and the bus line. The BSP also
controls the Error Management Logic (EML) and the parallel data stream between the
Tx/Rx Shift Register and the Intelligent Memory such that the processes of reception,
arbitration, transmission, and error signalling are performed according to the CAN
protocol. Note that the automatic retransmission of messages corrupted by noise or
other external error conditions on the bus line is handled by the BSP.
Cyclic Redundancy Check Register
This register generates the Cyclic Redundancy Check (CRC) code to be transmitted
after the data bytes and checks the CRC code of incoming messages. This is done by
dividing the data stream by the code generator polynomial.
Error Management Logic
The Error Management Logic (EML) is responsible for the fault confinement of the CAN
device. Its two counters (the Receive Error Counter and the Transmit Error Counter), are
incremented and decremented by commands from the Bit Stream Processor. According
to the values of the error counters, the CAN controller is set into one of three states:
error active, error passive, and busoff.
The CAN controller states occur as follows:
• Error active, if both error counters are below the error passive limit of 128.
• Error passive, if at least one of the error counters equals or exceeds 128.
• Busoff, if the Transmit Error Counter equals or exceeds the busoff limit of 256.
The device remains in this state until the busoff recovery sequence is finished.
Additionally, bit EWRN in the Status Register is set if at least one of the error counters
equals or exceeds the error warning limit of 96. EWRN is reset if both error counters are
less than the error warning limit.
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Derivatives
On-Chip CAN Interface
Bit Timing Logic
The Bit Timing Logic (BTL) monitors the busline input CAN_RXD and handles the
busline related bit timing according to the CAN protocol.
The BTL synchronizes on a recessive to dominant busline transition at Start of Frame
(hard synchronization) and on any further recessive to dominant busline transition, if the
CAN controller itself does not transmit a dominant bit (resynchronization).
The BTL also provides programmable time segments to compensate for the propagation
delay time and for phase shifts and to define the position of the Sample Point in the bit
time. The programming of the BTL depends on the baudrate and on external physical
delay times.
Intelligent Memory
The Intelligent Memory (CAM/RAM Array) provides storage for up to 15 message objects
of 8 data bytes maximum length. Each of these objects has a unique identifier and its
own set of control and status bits. After the initial configuration, the Intelligent Memory
can handle the reception and transmission of data without further CPU actions.
Organization of Registers and Message Objects
All registers and message objects of the CAN controller are located in the special CAN
address area of 256 Bytes. This area is mapped into segment 0 and uses addresses
00’EF00H through 00’EFFFH. All registers are organized as 16-bit registers, located on
word addresses. However, all registers may be accessed bytewise in order to select
special actions without affecting other mechanisms.
Register Naming reflects the specific name of a register as well as a general module
indicator. This results in unique register names.
Example: module indicator C1 (CAN module 1) and specific register type Control/Status
Register (CSR) produces unique register name C1CSR.
Note: The address map shown in Figure 19-3 below lists the registers which are part of
the CAN controller. There are also C164CM specific registers associated with the
CAN module.
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Derivatives
On-Chip CAN Interface
EF00
EF10
EF20
EF30
EF40
EF50
EF60
EF70
EF80
EF90
EFA0
EFB0
EFC0
EFD0
EFE0
EFF0
H
General Registers
H
Message Object 1
H
Message Object 2
H
Message Object 3
H
Message Object 4
H
Message Object 5
H
Message Object 6
H
Message Object 7
H
Message Object 8
H
Message Object 9
H
Message Object 10
H
Message Object 11
H
Message Object 12
H
Message Object 13
H
Message Object 14
H
Message Object 15
LMLM
UMLM
CAN Address Area
General Registers
Control/Status
Register CSR
EF00
Interrupt Register
IR
EF02
Bit Timing Register
BTR
EF04
Global Mask Short
GMS
EF06
Global Mask Long
EF08
H
H
H
H
H
LGML
UGML
Mask of Last
Message
EF0C
H
MCA04392
Figure 19-3 CAN Module Address Map
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Derivatives
On-Chip CAN Interface
19.2
General Functional Description
The Control/Status Register (CSR) accepts general control settings for the module and
provides general status information.
CSR
Control/Status Register
15
14
12
11
-
RX
OK
TX
OK
LEC
TM CCE
0
r
rwh
rwh
rwh
rw
r
Bit
INIT
IE
SIE
EIE
CPS
CCE
TM
rh
10
9
8
7
Reset Value: XX01H
13
B
E
OFF WRN
rh
XReg (EF00H)
6
rw
5
4
3
CPS EIE
rw
rw
2
1
0
SIE
IE
INIT
rw
rw
rwh
Function (Control Bits)
Initialization
Starts the initialization of the CAN controller, when set.
INIT is set – after a reset
– when entering the busoff state
– by the application software
Interrupt Enable
Enables or disables interrupt generation from the CAN module via the signal
XINTR. Does not affect status updates.
Status Change Interrupt Enable
Enables or disables interrupt generation when a message transfer
(reception or transmission) is successfully completed or a CAN bus error is
detected (and registered in the status partition).
Error Interrupt Enable
Enables or disables interrupt generation on a change of bit BOFF or EWRN
in the status partition).
Clock Prescaler Control Bit
0:
Standard mode: the input clock is divided 2:1. The minimum
input frequency to achieve a baudrate of 1 Mbit/s is fCPU = 16 MHz.
1:
Fast mode: the input clock is used directly 1:1. The minimum
input frequency to achieve a baudrate of 1 Mbit/s is fCPU = 8 MHz.
Configuration Change Enable
Allows or inhibits CPU access to the Bit Timing Register (BTR) and the
Interface Port Control bit field (IPC) in register PCIR.
Test Mode (must be ‘0’)
This bit must always be cleared when writing to the Control Register as this
bit controls a special test mode used for production testing only. During
normal operation, use of this test mode may lead to undesired behavior of
the device.
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Derivatives
On-Chip CAN Interface
Bit
LEC
TXOK
RXOK
EWRN
BOFF
Function (Control Bits)
Last Error Code
This field holds a code indicating the type of error which last occurred on the
CAN bus. If a message has been transferred (reception or transmission)
without error, this field will be cleared.
0
No Error
1
Stuff Error: More than 5 equal bits in a sequence have occurred in a
part of a received message where this is not allowed.
2
Form Error: Wrong format in fixed format part of a received frame.
3
AckError: The message transmitted by this CAN controller was not
acknowledged by another node.
4
Bit1Error: During the transmission of a message (with the exception
of the arbitration field), the device wanted to send a recessive level
(“1”), but the monitored bus value was dominant.
5
Bit0Error: During the transmission of a message (or acknowledge bit,
active error flag, or overload flag), the device wanted to send a
dominant level (“0”), but the monitored bus value was recessive.
During busoff recovery this status is set each time a sequence of
11 recessive bits has been monitored. This enables the CPU to
monitor the proceeding of the busoff recovery sequence (indicates
that the bus is not stuck at dominant or continuously disturbed).
6
CRCError: The received CRC check sum was incorrect.
7
Unused code: may be written by the CPU to check for updates.
Transmitted Message Successfully
Indicates that a message has been transmitted successfully (error free and
acknowledged by at least one other node), since this bit was last reset by the
CPU (the CAN controller does not reset this bit!).
Received Message Successfully
This bit is set each time a message has been received successfully, since
this bit was last reset by the CPU (the CAN controller does not reset this bit!).
RXOK is also set when a message is received that is not accepted (i.e.
stored).
Error Warning Status
Indicates that at least one of the error counters in the EML has reached the
error warning limit of 96.
Busoff Status
Indicates when the CAN controller is in busoff state (see EML).
Note: Reading the upper half of the Control Register (status partition) will clear the
Status Change Interrupt value in the Interrupt Register, if it is pending. Using byte
accesses to the lower half will avoid this.
User’s Manual
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Derivatives
On-Chip CAN Interface
19.2.1
CAN Interrupt Handling
The on-chip CAN module has one interrupt output. It is connected through a
synchronization stage to a standard interrupt node in the C164CM in the same manner
as all other interrupts of the standard on-chip peripherals. All control options are
available for this interrupt, such as enabling/disabling, level and group priority, and
interrupt or PEC service (see note below). The on-chip CAN module is connected to an
XBUS interrupt control register.
As for all other interrupts, the node interrupt request flag is cleared automatically by
hardware when this interrupt is serviced (either by standard interrupt or PEC service).
Note: As a rule, CAN interrupt requests can be serviced by a PEC channel. However,
because PEC channels can execute only single predefined data transfers (there
are no conditional PEC transfers), PEC service can be used only if the respective
request is known to be generated by one specific source, and on condition that no
other interrupt request will be generated in between. In practice, this seems to be
rare.
Because an interrupt request of the CAN module can be generated by various
conditions, the appropriate CAN interrupt status register must be read in the service
routine to determine the cause of the interrupt request. The interrupt identifier INTID (a
number) in the Port Control/Interrupt Register (PCIR) indicates the cause of an interrupt.
When no interrupt is pending, the identifier will have the value 00H.
If the value in INTID is not 00H, then there is an interrupt pending. If bit IE in the control/
status register is also set, the interrupt signal to the CPU is activated. The interrupt signal
(to the interrupt node) remains active until INTID becomes 00H (all interrupt requests
have been serviced) or until interrupt generation is disabled (CSR.IE = ‘0’).
Note: The interrupt node is activated only upon a 0 → 1 transition of the CAN interrupt
signal. The CAN interrupt service routine should only be exited after INTID has
been verified to be 00H.
The interrupt with the lowest number has the highest priority. If a higher priority interrupt
(lower number) occurs before the current interrupt is processed, INTID is updated and
the new interrupt overrides the last one.
INTID is also updated after the respective source request has been processed. This is
indicated by clearing the INTPND flag in the respective object’s message control register
(MCRn) or by reading the status partition of register CSR (in the case of a status change
interrupt). The updating of INTID is done by the CAN state machine and takes up to
6 CAN clock cycles, depending on current state of the state machine (1 CAN clock cycle
= 1 or 2 CPU clock cycles, as determined by the prescaler bit CPS).
Note: A worst case condition can occur when BRP = 00H AND the CAN controller is storing
a message just received AND the CPU is executing consecutive accesses to the CAN
module. In this rare case, the maximum delay may be 26 CAN clock cycles.
The impact of this delay can be minimized by clearing bit INTPND at an early stage
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Derivatives
On-Chip CAN Interface
of interrupt processing, and (if required) restricting CPU accesses to the CAN
module until the anticipated update is complete.
PCIR
Port Control / Interrupt Register XReg (EF02H)
15
14
13
12
11
- reserved -
-
-
-
-
10
9
8
7
Reset Value: XXXXH
6
5
4
3
IPC
INTID
rw
rh
Bit
Function
INTID
Interrupt Identifier
This number indicates the cause of the interrupt (if pending).
00H
01H
2
1
0
Interrupt Idle: There is no interrupt request pending.
Status Change Interrupt: The CAN controller has updated (not
necessarily changed) the status in the Control Register. This can
refer to a change of the error status of the CAN controller (EIE is
set and BOFF or EWRN change) or to a CAN transfer incident
(SIE must be set), such as reception or transmission of a message
(RXOK or TXOK is set) or the occurrence of a CAN bus error (LEC
is updated). The CPU may clear RXOK, TXOK, and LEC,
however, writing to the status partition of the Control Register can
never generate or reset an interrupt. The status partition of the
Control Register must be read to update the INTID value.
02H
IPC
Message 15 Interrupt: Bit INTPND in the Message Control
Register of message object 15 (last message) has been set.
The last message object has the highest interrupt priority of all
message objects.1)
(02 + N) Message N Interrupt: Bit INTPND in the Message Control
Register of message object ‘N’ has been set (N = 1 … 14). Note
that a message interrupt code is only displayed, if there is no other
interrupt request with a higher priority.1)
Example: message 1: INTID = 03H, message 14: INTID = 10H
Interface Port Control (reset value = 111B, i.e. no port connection)
The encoding of bitfield IPC is described in Section 19.6.
Note: Bitfield IPC can be written only while bit CCE is set.
1)
Bit INTPND of the corresponding message object has to be cleared to give messages with a lower priority the
possibility to update INTID or to reset INTID to “00H” (idle state).
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Derivatives
On-Chip CAN Interface
19.2.2
Configuration of the Bit Timing
According to the CAN protocol specification, a bit time is subdivided into four segments:
Sync segment, propagation time segment, phase buffer segment 1 and phase buffer
segment 2.
Each segment is a multiple of the time quantum tq, with
tq = (BRP + 1) × 2(1 - CPS) × tXCLK.
Note: The CAN module is connected to the CPU clock signal, therefore tXCLK = tCPU.
The Synchronization Segment (Sync Seg) is always 1 tq long. The Propagation Time
Segment and the Phase Buffer Segment 1 (combined to TSeg1) define the time before
the sample point, while Phase Buffer Segment 2 (TSeg2) defines the time after the
sample point. The length of these segments is programmable (except Sync-Seg) via the
Bit Timing Register (BTR).
Note: For exact definition of these segments please refer to the CAN Protocol
Specification.
1 Bit Time
SyncSeg
TSeg1
TSeg2
1 time quantum
(tq)
Sample Point
SyncSeg
Transmit Point
MCT04393
Figure 19-4 Bit Timing Definition
The bit time is determined by the XBUS clock period tXCLK, the Baud Rate Prescaler,
and the number of time quanta per bit:
bit time
= tSync-Seg + tTSeg1 + tTSeg2
[19.1]
tSync-Seg = 1 × tq
tTSeg1
= (TSEG1 + 1) × tq
tTSeg2
= (TSEG2 + 1) × tq
tq
= (BRP + 1) × 2(1 - CPS) × tXCLK
[19.2]
Note: TSEG1, TSEG2, and BRP are the programmed numerical values from the
respective fields of the Bit Timing Register.
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Derivatives
On-Chip CAN Interface
BTR
Bit Timing Register
15
14
13
12
XReg (EF04H)
11
10
9
8
7
Reset Value: UUUUH
6
5
4
3
2
0
TSEG2
TSEG1
SJW
BRP
r
rw
rw
rw
rw
1
0
Bit
Function
BRP
Baud Rate Prescaler
To generate the bit time quanta, the CPU frequency fCPU is divided by
2(1 - CPS) × (BRP + 1). See also the prescaler control bit CPS in register
CSR.
(Re)Synchronization Jump Width
Adjust the bit time by maximum (SJW + 1) time quanta for
resynchronization.
Time Segment before sample point
There are (TSEG1 + 1) time quanta before the sample point.
Valid values for TSEG1 are “2 … 15”.
SJW
TSEG1
TSEG2
Time Segment after sample point
There are (TSEG2 + 1) time quanta after the sample point.
Valid values for TSEG2 are “1 … 7”.
Note: This register can only be written, if the config. change enable bit (CCE) is set.
Hard Synchronization and Resynchronization
To compensate for phase shifts between clock oscillators of different CAN controllers,
any CAN controller must synchronize on any edge from recessive to dominant bus level
if the edge lies between a Sample Point and the next Synchronization Segment, and on
any other edge if it does not send a dominant level itself. If the Hard Synchronization is
enabled (at the Start of Frame), the bit time is restarted at the Synchronization Segment;
otherwise the Resynchronization Jump Width (SJW) defines the maximum number of
time quanta by which a bit time may be shortened or lengthened during one
Resynchronization. The current bit time is adjusted by
tSJW = (SJW + 1) × tq
Note: SJW is the programmed numerical value from the respective field of the Bit Timing
Register.
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On-Chip CAN Interface
Calculation of the Bit Time
Programming the bit time according to the CAN Specification depends on the desired
baudrate, the XCLK frequency, and the external physical delay times of the bus driver,
the bus line, and the input comparator. These delay times are summarized in the
Propagation Time Segment tProp, where
tProp is two times the maximum of the sum of physical bus delay, the input comparator
delay, and the output driver delay rounded up to the nearest multiple of tq.
To fulfill the requirements of the CAN specification, the following conditions must be met:
tTSeg2 ≥ 2 × tq = Information Processing Time
tTSeg2 ≥ tSJW
tTSeg1 ≥ 3 × tq
tTSeg1 ≥ tSJW + tProp
Note: In order to achieve correct operation according to the CAN protocol, the total bit
time should be at least 8 tq, i.e. TSEG1 + TSEG2 ≥ 5.
Thus, to operate with a baudrate of 1 MBit/s, the XCLK frequency must be at least
8/16 MHz (depending on the prescaler control bit CPS in register CSR).
The maximum tolerance df for XCLK depends on the Phase Buffer Segment 1 (PB1),
the Phase Buffer Segment 2 (PB2), and the Resynchronization Jump Width (SJW):
df
min ( PB1, PB2 )
≤ ---------------------------------------------------------------2 × ( 13 × bit time – PB2 )
AND
df
t
SJW
≤ -------------------------------20 × bit time
The following examples illustrate bit timing calculations under specific circumstances.
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Derivatives
On-Chip CAN Interface
Bit Timing Example for High Baudrate
This example makes the following assumptions:
• XCLK frequency = 20 MHz
• BRP = 00, CPS = 0
• Baudrate = 1 Mbit/s
tq
tProp
tSJW
tTSeg1
tTSeg2
tSync
tBit
100 ns
50 ns
30 ns
220 ns
600 ns
100 ns
700 ns
200 ns
100 ns
1000 ns
tolerance for tXCLK
0.39%
bus driver delay
receiver circuit delay
bus line (40 m) delay
= 2 × tXCLK
= 6 × tq
= 1 × tq
= tProp + tSJW
= Information Processing Time
= 1 × tq
= tSync + tTSeg1 + tTSeg2
min ( PB1, PB2 )
= ---------------------------------------------------------------2 × ( 13 × bit time – PB2 )
0,1 µ s
= ----------------------------------------------------------2 × ( 13 × 1 µ s – 0,2 µ s )
Bit Timing Example for Low Baudrate
This example makes the following assumptions:
• XCLK frequency = 4 MHz
• BRP = 01, CPS = 0
• Baudrate = 100 kbit/s
tProp
tSJW
tTSeg1
tTSeg2
tSync
tBit
1 µs
200 ns
80 ns
220 ns
1 µs
4 µs
5 µs
4 µs
1 µs
10 µs
tolerance for fXCLK
1.58%
tq
bus driver delay
receiver circuit delay
bus line (40 m) delay
= 4 × tXCLK
= 1 × tq
= 4 × tq
= tProp + tSJW
= Information Processing Time + 2 × tq
= 1 × tq
= tSync + tTSeg1 + tTSeg2
min ( PB1, PB2 )
= --------------------------------------------------------------2 × ( 13 × bit time – PB2 )
4µs
= --------------------------------------------------------2 × ( 13 × 10 µ s – 4 µ s )
User’s Manual
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Derivatives
On-Chip CAN Interface
19.2.3
Mask Registers
Messages can use either standard or extended identifiers. Incoming frames are masked
with their appropriate global masks. Bit IDE of the incoming message determines
whether the standard 11-bit mask in Global Mask Short (GMS), or the 29-bit extended
mask in Global Mask Long (UGML&LGML) is to be used. Bits holding a “0” are “don’t
care”, that is, do not compare the message’s identifier in the respective bit position.
The last message object (15) has an additional individually programmable acceptance
mask (Mask of Last Message, UMLM&LMLM) for the complete arbitration field. This
allows classes of messages to be received in this object by masking some bits of the
identifier.
Note: The Mask of Last Message is ANDed with the Global Mask that corresponds to
the incoming message.
GMS
Global Mask Short
15
14
13
XReg (EF06H)
7
Reset Value: UFUUH
12
11
10
9
8
6
5
4
3
ID20 … 18
1
1
1
1
1
ID28 … 21
rw
r
r
r
r
r
rw
Bit
Function
ID28 … 18
Identifier (11-bit)
Mask to filter incoming messages with standard identifier.
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Derivatives
On-Chip CAN Interface
UGML
Upper Global Mask Long
15
14
13
12
11
XReg (EF08H)
10
9
14
7
6
5
4
3
ID20 … 13
ID28 … 21
rw
rw
LGML
Lower Global Mask Long
15
8
Reset Value: UUUUH
13
12
11
XReg (EF0AH)
7
9
8
ID4 … 0
0
0
0
ID12 … 5
rw
r
r
r
rw
6
5
4
3
Bit
Function
ID28 … 0
Identifier (29-bit)
Mask to filter incoming messages with extended identifier.
19-16
1
0
Reset Value: UUUUH
10
User’s Manual
2
2
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Derivatives
On-Chip CAN Interface
UMLM
Upper Mask of Last Message
15
14
13
12
11
10
XReg (EF0CH)
9
8
7
Reset Value: UUUUH
6
5
4
3
ID20 … 18
ID17 … 13
ID28 … 21
rw
rw
rw
LMLM
Lower Mask of Last Message
15
14
13
12
11
XReg (EF0EH)
7
2
1
Reset Value: UUUUH
10
9
8
ID4 … 0
0
0
0
ID12 … 5
rw
r
r
r
rw
6
5
4
3
2
1
Bit
Function
ID28 … 0
Identifier (29-bit)
Mask to filter the last incoming message (Nr. 15) with standard or
extended identifier (as configured).
User’s Manual
19-17
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Derivatives
On-Chip CAN Interface
19.3
The Message Object
The message object is the primary means of communication between the CPU and the
CAN controller. Each of the 15 message objects uses 15 consecutive bytes (see
Figure 19-5) and starts at an address that is a multiple of 16.
Note: All message objects must be initialized by the CPU before clearing the INIT bit,
even those which are not going to be used.
Offset
+0
Message Control ( MCR)
Object Start Address (EFn0 )
H
+2
Arbitration (UAR&LAR)
+4
Message Object 1: EF10
H
Data0
Msg. Config. ( MCFG)
+6
Message Object 2: EF20
Data2
Data1
+8
...
Data4
Data3
+10
Message Object 14: EFE0
Data6
Data5
+12
Message Object 15: EFF0
Reserved
Data7
+14
H
H
H
MCA04394
Figure 19-5 Message Object Address Map
The general properties of a message object are defined via the Message Control
Register (MCR). There is a dedicated register MCRn for each message object n.
Each element of the Message Control Register consists of two complementary bits. This
special mechanism allows the selective setting or resetting of specific elements (leaving
others unchanged) without requiring read-modify-write cycles. None of these elements
will be affected by reset.
Table 19-1 shows the functions and meanings of these 2-bit fields.
Table 19-1
MCR Bitfield Encoding
Value
Function on Write
Meaning on Read
0
0
– Reserved –
– Reserved –
0
1
Reset element
Element is reset
1
0
Set element
Element is set
1
1
Leave element unchanged
– Reserved –
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Derivatives
On-Chip CAN Interface
MCRn
Message Control Register
15
14
13
12
11
XReg (EFn0H)
10
9
8
7
Reset Value: UUUUH
6
5
4
3
2
1
0
RMTPND
TXRQ
MSGLST
CPUUPD
NEWDAT
MSGVAL
TXIE
RXIE
INTPND
rw
rw
rw
rw
rw
rw
rw
rw
Bit
Function
INTPND
Interrupt Pending
Indicates whether this message object has generated an interrupt
request (see TXIE and RXIE), since this bit was last reset by the CPU.
RXIE
Receive Interrupt Enable
Defines whether bit INTPND is set after successful reception of a frame.
TXIE
Transmit Interrupt Enable
Defines whether bit INTPND is set after successful transmission of a
frame.1)
MSGVAL
Message Valid
Indicates whether the corresponding message object is valid. The CAN
controller only operates on valid objects. Message objects can be tagged
invalid, while they are changed, or if they are not used at all.
NEWDAT
New Data
Indicates whether new data has been written into the data portion of this
message object by CPU (transmit-objects) or CAN controller (receiveobjects) since this bit was last reset.2)
MSGLST
Message Lost (This bit applies to receive-objects only!)
Indicates that the CAN controller has stored a new message into this
object while NEWDAT was still set; thus, the previously stored message
is lost.
CPUUPD
CPU Update (This bit applies to transmit-objects only!)
Indicates that the corresponding message object may not be transmitted
now. The CPU sets this bit to inhibit transmission of a message currently
being updated, or to control the automatic response to remote requests.
TXRQ
Transmit Request
Indicates that the transmission of this message object is requested by
the CPU or via a remote frame and is not yet complete. TXRQ can be
disabled by CPUUPD.1)3)
User’s Manual
19-19
V1.0, 2002-02
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Derivatives
On-Chip CAN Interface
Bit
Function
RMTPND
Remote Pending (Used for transmit-objects)
Indicates that the transmission of this message object has been
requested by a remote node, but the data has not yet been transmitted.
When RMTPND is set, the CAN controller also sets TXRQ. Bits
RMTPND and TXRQ are cleared when the message object has been
successfully transmitted.
1)
In message object 15 (last message) these bits are hardwired to “0” (inactive) in order to prevent transmission
of message 15.
2)
When the CAN controller writes new data into the message object, unused message bytes will be overwritten
by non specified values. Usually the CPU will clear this bit before working on the data, and verify that the bit is
still cleared once it has finished working to ensure that it has worked on a consistent set of data and not part
of an old message and part of the new message.
For transmit-objects the CPU will set this bit along with clearing bit CPUUPD. This will ensure that, if the
message is actually being transmitted during the time the message was being updated by the CPU, the CAN
controller will not reset bit TXRQ. In this way bit TXRQ is only reset once the actual data has been transferred.
3)
When the CPU requests the transmission of a receive-object, a remote frame will be sent instead of a data
frame to request a remote node to send the corresponding data frame. This bit will be cleared by the CAN
controller along with bit RMTPND when the message has been successfully transmitted, if bit NEWDAT has
not been set.
If there are several valid message objects with pending transmission request, the message with the lowest
message number is transmitted first. This arbitration is done when several objects are requested for
transmission by the CPU, or when operation is resumed after an error frame or after arbitration has been lost.
Arbitration Registers
The Arbitration Registers (UARn&LARn) are used for acceptance filtering of incoming
messages and to define the identifier of outgoing messages. A received message with
a matching identifier is accepted as a data frame (matching object has DIR = ‘0’) or as a
remote frame (matching object has DIR = ‘1’). For matching, the corresponding Global
Mask must be considered (the Mask of Last Message must also be considered for
message object 15). Extended frames (using Global Mask Long) can be stored only in
message objects with XTD = ‘1’, standard frames (using Global Mask Short) can be
stored only in message objects with XTD = ‘0’.
Message objects should have unique identifiers such that if some bits are masked out
by the Global Mask Registers (“don’t care” bits), then the identifiers of the valid message
objects should differ in the remaining bits which are used for acceptance filtering.
If a received message (data frame or remote frame) matches with more than one valid
message object, it is associated with the object having the lowest message number.
Thus, a received data frame is stored in the “lowest” object, or the “lowest” object is sent
in response to a remote frame. The Global Mask is used for this matching.
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V1.0, 2002-02
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Derivatives
On-Chip CAN Interface
After a transmission (data frame or remote frame) the transmit request flag of the
matching object with the lowest message number is cleared. The Global Mask is not
used in this case.
When the CAN controller accepts a data frame, the complete message is stored into
the corresponding message object including the identifier (also masked bits, standard
identifiers have bits ID17-0 filled with ‘0’), the data length code (DLC), and the data bytes
(valid bytes indicated by DLC). This is implemented to keep the data bytes connected
with the identifier even if arbitration mask registers are used.
When the CAN controller accepts a remote frame, the corresponding transmit
message object (1 … 14) remains unchanged except for bits TXRQ and RMTPND,
which are set. In the last message object 15 (which cannot start a transmission), the
identifier bits corresponding to the “don’t care” bits of the Last Message Mask are copied
from the received frame. Bits corresponding to the “don’t care” bits of the corresponding
global mask are not copied (bits masked out by the global and the last message mask
cannot be retrieved from object 15).
UARn
Upper Arbitration Register
15
14
13
12
11
ID20 … 18
XReg (EFn2H)
10
9
8
7
Reset Value: UUUUH
6
5
ID17 … 13
4
13
12
1
0
rw
LARn
Lower Arbitration Register
14
2
ID28 … 21
rw
15
3
11
XReg (EFn4H)
7
Reset Value: UUUUH
10
9
8
6
5
4
3
ID4 … 0
0
0
0
ID12 … 5
rw
r
r
r
rw
2
1
0
Bit
Function
ID28 … 0
Identifier (29-bit)
Identifier of a standard message (ID28 … 18) or an extended message
(ID28 … 0). For standard identifiers, bits ID17 … 0 are “don’t care”.
User’s Manual
19-21
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Derivatives
On-Chip CAN Interface
Message Configuration
The Message Configuration Register (low byte of MCFGn) holds a description of the
message within this object.
Note: There is no “don’t care” option for bits XTD and DIR. So, incoming frames can only
match with corresponding message objects either standard (XTD = 0) or extended
(XTD = 1). Data frames match with receive-objects only; remote frames match
with transmit-objects only.
When the CAN controller stores a data frame, it will write all the eight data bytes
into a message object. If the data length code was less than 8, the remaining bytes
of the message object will be overwritten by non-specified values.
MCFGn
Message Configuration Reg.
15
14
13
12
11
10
XReg (EFn6H)
9
8
7
Reset Value: - - UUH
6
5
Data Byte 0
DLC
rw
rw
4
3
2
DIR XTD
rw
rw
1
0
0
0
r
r
Bit
Function
XTD
Extended Identifier
0:
Standard
This message object uses a standard 11-bit identifier.
1:
Extended
This message object uses an extended 29-bit identifier.
DIR
Message Direction
0:
Receive Object.
On TXRQ, a remote frame with the identifier of this message
object is transmitted.
On reception of a data frame with matching identifier, that
message is stored in this message object.
1:
Transmit Object.
On TXRQ, the respective message object is transmitted.
On reception of a remote frame with matching identifier, the TXRQ
and RMTPND bits of this message object are set.
DLC
Data Length Code
Defines the number of valid data bytes within the data area.
Valid values for the data length are 0 … 8.
Note: The first data byte occupies the upper half of the message configuration register.
User’s Manual
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Derivatives
On-Chip CAN Interface
Data Area
The data area occupies 8 successive byte positions after the Message Configuration
Register such that the data area of message object n covers locations 00’EFn7H through
00’EFnEH.
Location 00’EFnFH is reserved.
Message data for message object 15 (last message) will be written into a two-messagealternating buffer to avoid the loss of a message, if a second message has been
received, before the CPU has read the first one.
Handling of Message Objects
Figure 19-6 through Figure 19-11 summarize the actions which must be taken to
transmit and receive messages over the CAN bus. The actions taken by the CAN
controller are described as well as the actions to be taken by the CPU (the servicing
program).
The diagrams show these actions:
•
•
•
•
•
•
CAN controller handling of transmit objects
CAN controller handling of receive objects
CPU handling of transmit objects
CPU handling of receive objects
CPU handling of last message object
Handling of the last message’s alternating buffer
User’s Manual
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Derivatives
On-Chip CAN Interface
yes
no
Bus free?
TXRQ = 1
CPUUPD = 0
no
Received remote frame
with same identifier as
this message object?
no
yes
yes
NEWDAT := 0
Load message
into buffer
TXRQ := 1
RMTPND := 1
Send message
RXIE = 1?
no
yes
no
Transmission
successful?
INTPND := 1
yes
NEWDAT = 1?
no
TXRQ := 0
RMTPND := 0
yes
no
TXIE = 1?
yes
INTPND := 1
0: Reset
1: Set
MCA04395
Figure 19-6 CAN Controller Handling of Transmit Objects (DIR = ‘1’)
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Derivatives
On-Chip CAN Interface
yes
no
no
Bus idle?
TXRQ = 1?
CPUUPD = 0?
Received frame with
same identifier as this
message object?
no
yes
yes
NEWDAT := 0
Load identifier and
control into buffer
yes
NEWDAT = 1
no
Send remote frame
MSGLST := 1
no
Transmission
successful?
yes
no
TXRQ := 0
RMTPND := 0
Store message
NEWDAT := 1
TXRQ := 0
RMTPND := 0
TXIE = 1?
RXIE = 1?
yes
no
yes
INTPND := 1
INTPND := 1
0: Reset
1: Set
MCA04396
Figure 19-7 CAN Controller Handling of Receive Objects (DIR = ‘0’)
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Derivatives
On-Chip CAN Interface
Power Up
(all bits undefined)
TXIE := (application cpecific)
RXIE := (application cpecific)
INTPND := 0
RMTPND := 0
TXRQ := 0
CPUUPD := 1
Identifier := (application cpecific)
NEWDAT := 0
Direction := transmit
DLC := (application cpecific)
MSGVAL := 1
XTD := (application cpecific)
Initialization
CPUUPD := 1
NEWDAT := 1
Update: Start
Update
Write / calculate message contents
Update: End
CPUUPD := 0
yes
Want to send?
no
TXRQ := 1
no
0: Reset
1: Set
Update
message?
yes
MCA04397
Figure 19-8 CPU Handling of Transmit Objects (DIR = ‘1’)
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Derivatives
On-Chip CAN Interface
Power Up
Initialization
(all bits undefined)
TXIE := (application cpecific)
RXIE := (application cpecific)
INTPNDd := 0
RMTPND := 0
TXRQ := 0
MSGLST := 0
Identifier := (application cpecific)
NEWDAT := 0
Direction := receive
DLC := (value of DLC in transmitter)
MSGVAL := 1
XTD := (application cpecific)
Process: Start
NEWDAT := 0
Process message contents
Process
Process: End
NEWDAT = 1?
yes
Restart process
no
no
Request
Update?
yes
TXRQ := 1
0: Reset
1: Set
MCA04398
Figure 19-9 CPU Handling of Receive Objects (DIR = ‘0’)
User’s Manual
19-27
V1.0, 2002-02
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Derivatives
On-Chip CAN Interface
Power Up
Initialization
Process: Start
(all bits undefined)
RXIE := (application cpecific)
INTPND := 0
RMTPND := 0
MSGLST := 0
Identifier := (application cpecific)
NEWDAT := 0
Direction := receive
DLC := (value of DLC in transmitter)
MSGVAL := 1
XTD := (application cpecific)
Process message contents
NEWDAT := 0
Process
Process: End
NEWDAT = 1?
yes
Restart process
no
0: Reset
1: Set
MCA04399
Figure 19-10 CPU Handling of the Last Message Object
User’s Manual
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Derivatives
On-Chip CAN Interface
Reset
CPU releases Buffer 2
CPU releases Buffer 1
Buffer 1 = Released
Buffer 2 = Released
CPU access to Buffer 2
Store received
message into Buffer 1
CPU allocates Buffer 2
Buffer 1 = Released
Buffer 2 = Allocated
CPU access to Buffer 2
Buffer 1 = Allocated
Buffer 2 = Released
CPU access to Buffer 1
Store received
message
into Buffer 1
Store received
message
into Buffer 2
Buffer 1 = Allocated
Buffer 2 = Allocated
CPU access to Buffer 2
Store received
message into
Buffer 1
MSGLST is set
Allocated:
Released:
Buffer 1 = Allocated
Buffer 2 = Allocated
CPU access to Buffer 1
CPU releases CPU releases
Buffer 2
Buffer 1
NEWDAT = 1 or RMTPND = 1
NEWDAT = 0 and RMTPND = 0
Store received
message into
Buffer 2
MSGLST is set
MCA04400
Figure 19-11 Handling of the Last Message Object’s Alternating Buffer
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Derivatives
On-Chip CAN Interface
19.4
Controlling the CAN Module
The CAN module is controlled by the C164CM via hardware signals (e.g. reset) and via
register accesses executed by software.
Accessing the On-Chip CAN Module
The CAN module is implemented as an X-Peripheral and is therefore accessed like an
external memory or peripheral. This means that the registers of the CAN module can be
read and written using 16-bit or 8-bit direct or indirect MEM addressing modes. Bit
handling is not supported via the XBUS. Since the XBUS, to which the CAN module is
connected, also represents the external bus, CAN accesses follow the same rules and
procedures as accesses to the external bus. CAN accesses cannot be executed in
parallel to external instruction fetches or data read/writes, but are arbitrated and inserted
into the external bus access stream.
Accesses to the CAN module use demultiplexed addresses, a 16-bit data bus (byte
accesses are possible), two waitstates, and no tristate waitstate.
The CAN address area starts at 00’EF00H and covers 256 Bytes. This area is decoded
internally, so none of the programmable address windows must be sacrificed in order to
access the on-chip CAN module.
The advantage of locating the CAN address area in segment 0 is that the CAN module
is accessible via data page 3. This is the ‘system’ data page, accessed usually through
the ‘system’ data page pointer DPP3. In this way, internal addresses (such like SFRs,
internal RAM, and the CAN registers), are all located within the same data page and form
a contiguous address space.
Power Down Mode
If the C164CM enters Power Down mode, the XCLK signal will be turned off. This stops
the operation of the CAN module; thus, any message transfer is interrupted. To ensure
that the CAN controller is not stopped while sending a dominant level (‘0’) on the CAN
bus, the CPU should set bit INIT in the Control Register prior to entering Power Down
mode. The CPU can determine if a transmission is in progress by reading bits TXRQ and
NEWDAT in the message objects and bit TXOK in the Control Register. After returning
from Power Down mode via hardware reset, the CAN module must be reconfigured.
User’s Manual
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Derivatives
On-Chip CAN Interface
Disabling the CAN Modules
When the CAN module is disabled by setting bit CAN1DIS in register SYSCON3
(peripheral management), no register accesses are possible. The module’s logic blocks
are also stopped; so no CAN bus transfers are possible. When the CAN module is reenabled (CAN1DIS = ‘0’) it must be reconfigured (as after return from Power Down
mode).
Note: Incoming message frames can still be recognized (not received) in this case by
monitoring the receive line CAN1_RXD. For this purpose, the receive line
CAN1_RXD can be connected to a fast external interrupt via register EXISEL.
CAN Module Reset
The on-chip CAN module is connected to the XBUS Reset signal. This signal is activated
when the C164CM’s reset input is activated, when a software reset is executed, and in
case of a watchdog reset. Activating the CAN module’s reset line triggers a hardware
reset.
This hardware reset has the following effects:
•
•
•
•
•
•
Disconnects the CAN_TXD output from the port logic
Clears the error counters
Resets the busoff state
Switches the Control Register’s low byte to 01H
Leaves the Control Register’s high byte and the Interrupt Register undefined
Does not change other registers, including the message objects (notified as UUUU)
Note: The first hardware reset after power-on leaves the unchanged registers in an
undefined state, of course.
The value 01H in the Control Register’s low byte prepares for the module
initialization.
CAN Module Activation
The CAN module is disabled after a reset. Before it can be used to receive or transmit
messages, the application software must activate the CAN module.
Three actions are required for this purpose:
• General Module Enable globally activates the CAN module by setting bit XPEN in
register SYSCON after setting the corresponding selection bit in register XPERCON.
• Pin Assignment selects a pair of port pins to connect the CAN module to the external
transceiver. This is done via bitfield IPC in register PCIR.
• Module Initialization determines the functionality of the CAN module (baudrate,
active objects, etc.). This is the major part of the activation and is described below.
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Derivatives
On-Chip CAN Interface
Module Initialization
Module initialization is enabled by setting bit INIT in the control register CSR. This can
be done by the CPU via software, or by the CAN controller automatically on a hardware
reset, or if the EML switches to busoff state.
While INIT is set:
•
•
•
•
All message transfer from and to the CAN bus is stopped
The CAN transmit line CAN_TXD is “1” (recessive)
Control bits NEWDAT and RMTPND of the last message object are reset
Counters of the EML are left unchanged.
Additionally, setting bit CCE permits configuration changes in the Bit Timing Register.
To initialize the CAN Controller, the following actions are required:
• Configure the Bit Timing Register (CCE required)
• Set the Global Mask Registers
• Initialize each message object.
If a message object is not needed, it is sufficient to clear its message valid bit (MSGVAL),
that is, to define it as not valid. Otherwise, the entire message object must be initialized.
After the initialization sequence has been completed, the CPU clears bit INIT.
Now, the BSP synchronizes itself to the data transfer on the CAN bus by waiting for the
occurrence of a sequence of 11 consecutive recessive bits (i.e. Bus Idle) before it can
take part in bus activities and start message transfers.
Initialization of the message objects is independent of the state of bit INIT and can be
done on the fly. The message objects should all be configured to particular identifiers or
set to “not valid” before the BSP starts the message transfer, however.
To change the configuration of a message object during normal operation, the CPU first
clears bit MSGVAL, which defines it as not valid. When the configuration is completed,
MSGVAL is set again.
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Derivatives
On-Chip CAN Interface
Busoff Recovery Sequence
If the device goes busoff, it will set bit BOFF and bit INIT of its own accord, stopping all
bus activities. For the CAN module to take part in the CAN bus activities again, the busoff recovery sequence must be started by clearing the bit INIT (via software). After INIT
has been cleared, the module will then wait for 129 occurrences of Bus idle before
resuming normal operation.
At the end of the busoff recovery sequence, the Error Management Counters will be
reset. This will automatically clear bits BOFF and EWRN.
During the waiting time after the resetting of INIT each time a sequence of 11 recessive
bits has been monitored, a Bit0Error code is written to the Control Register, enabling
the CPU to determine whether the CAN bus is stuck at dominant or continuously
disturbed and to monitor the progress of the busoff recovery sequence.
Note: An interrupt can be generated when entering the busoff state if bits IE and EIE are
set. The corresponding interrupt code in bitfield INTID is 01H.
The busoff recovery sequence cannot be shortened by setting or resetting INIT.
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Derivatives
On-Chip CAN Interface
19.5
Configuration Examples for Message Objects
The two examples below represent standard applications for using CAN messages. Both
examples assume that the identifier and direction have already been set up correctly.
The respective contents of the Message Control Register (MCR) are shown.
Configuration Example of a Transmission Object
This object shall be configured for transmission. It shall be transmitted automatically in
response to remote frames, but no receive interrupts shall be generated for this object.
MCR (Data bytes are not written completely → CPUUPD = ‘1’)
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
01
01
10
01
10
01
01
01
RMTPND
TXRQ
CPUUPD
NEWDAT
MSGVAL
TXIE
RXIE
INTPND
MCR (Remote frame was received in the meantime → RMTPND = ‘1’, TXRQ = ‘1’)
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
10
10
10
01
10
01
01
01
RMTPND
TXRQ
CPUUPD
NEWDAT
MSGVAL
TXIE
RXIE
INTPND
After updating the message, the CPU should clear CPUUPD and set NEWDAT. The
previously received remote request will then be answered.
If the CPU wants to transmit the message actively, it should also set TXRQ (otherwise
TXRQ should be left unchanged).
User’s Manual
19-34
V1.0, 2002-02
C164CM/C164SM
Derivatives
On-Chip CAN Interface
Configuration Example of a Reception Object
This object shall be configured for reception. A receive interrupt shall be generated each
time new data comes in. From time to time, the CPU sends a remote request to trigger
the sending of this data from a remote node.
MCR (Message object is idle, i.e. waiting for a frame to be received)
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
01
01
01
01
10
01
10
01
RMTPND
TXRQ
MSGLST
NEWDAT
MSGVAL
TXIE
RXIE
INTPND
.
MCR (A data frame was received → NEWDAT = ‘1’, INTPND = ‘1’)
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
01
01
01
10
10
01
10
10
RMTPND
TXRQ
MSGLST
NEWDAT
MSGVAL
TXIE
RXIE
INTPND
To process the message, the CPU should clear INTPND and NEWDAT, process the
data, and verify that NEWDAT is still clear after that. If it is not clear, the processing
should be repeated.
To send a remote frame to request the data, bit TXRQ simply needs to be set. This bit
will be cleared by the CAN controller after the remote frame has been sent or if the data
is received before the CAN controller could transmit the remote frame.
User’s Manual
19-35
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C164CM/C164SM
Derivatives
On-Chip CAN Interface
19.6
CAN Application Interface
The on-chip CAN module of the C164CM is connected to the (external) physical layer
(i.e. the CAN bus) via two signals, as shown in Table 19-2.
Table 19-2
CAN Interface Signals
CAN Signal
Port Pin
CAN1_RxD
Controlled via Receive data from the physical layer of the CAN bus 1
C1PCIR.IPC Transmit data to the physical layer of the CAN bus 1
CAN1_TxD
Function
A logic low level (‘0’) is interpreted as the dominant CAN bus level, a logic high level (‘1’)
is interpreted as the recessive CAN bus level.
Connection to an External Transceiver
The CAN module of the C164CM can be connected to an external CAN bus via a CAN
transceiver.
CAN_RxD
CAN
Transceiver
CAN 1
CAN_TxD
Physical
Layer
CAN Bus
Note: It is also possible to connect several CAN modules directly (on-board) without
using CAN transceivers.
MCS04401
Figure 19-12 Connection to a Single CAN Bus
User’s Manual
19-36
V1.0, 2002-02
C164CM/C164SM
Derivatives
On-Chip CAN Interface
Port Control
The receive data line and the transmit data line of the CAN module are alternate port
functions. To enable proper reception, please ensure that the respective port pin for the
receive line is switched to input. The respective port driver for the transmit will
automatically be switched ON.
This provides a standard pin configuration without additional software control. It also
works in emulation mode where the port direction registers cannot be controlled.
The receive and transmit line of the CAN module may be assigned to several port pins
of the C164CM under software control. This assignment is selected via bitfield IPC
(Interface Port Connection) in register PCIR.
Table 19-3
Assignment of CAN Interface Lines to Port Pins
IPC
CAN_RxD
CAN_TxD
Notes
000
–
–
Reserved. Do not use this combination.
001
–
–
Reserved. Do not use this combination.
010
P8.0
P8.1
–
011
P8.2
P8.3
–
100
–
–
Reserved. Do not use this combination.
101
–
–
Reserved. Do not use this combination.
110
–
–
Reserved. Do not use this combination.
111
Idle
(recessive)
Disconnected No port assigned. Default after Reset.
The location of the CAN interface lines can now be selected via software according to
the requirements of an application:
Port Assignment (IPC = 010B or 011B) connects the CAN interface lines to Port 8. Two
pairs of Port 8 pins can be selected.
No Assignment (IPC = 111B) disconnects the CAN interface lines from the port logic.
This avoids undesired currents through the interface pin drivers while the C164CM is in
a power saving state.
After reset the CAN interface lines are disconnected.
Note: Assigning CAN interface signals to a port pin overrides the other alternate function
of the respective pin (CAPCOM lines on Port 8).
User’s Manual
19-37
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
20
System Reset
The internal system reset function provides initialization of the C164CM into a defined
default state. The default state is invoked either by asserting a hardware reset signal on
pin RSTIN (Hardware Reset Input), by executing the SRST instruction (Software Reset),
or by an overflow of the watchdog timer.
Whenever one of these conditions occurs, the microcontroller is reset into its predefined
default state through an internal reset procedure. When a reset is initiated, pending
internal hold states are cancelled and the current internal access cycle (if any) is
completed. An external bus cycle is aborted, except for a watchdog reset (see
description). Afterwards, the bus pin drivers and the IO pin drivers are switched off
(tristate).
The internal reset procedure requires 516 CPU clock cycles in order to perform a
complete reset sequence. This 516 cycle reset sequence is started by a watchdog timer
overflow, by an SRST instruction or when the reset input signal RSTIN is latched low
(hardware reset). The internal reset condition is active for at least the duration of the
reset sequence and then until the RSTIN input is inactive and the PLL has locked (if the
PLL is selected for the basic clock generation). When this internal reset condition is
removed (reset sequence complete, RSTIN inactive, PLL locked), the reset
configuration is latched from PORT0, RD, and ALE (depending on the start mode).
Afterwards, pins ALE, RD, and WR are driven to their inactive levels.
Note: Bit ADP (which selects the Adapt mode) is latched with the rising edge of RSTIN.
After the internal reset condition is removed, the microcontroller will either start program
execution from external or internal memory, or it will enter boot mode.
RSTOUT
External
Hardware
VDD
Reset
a)
RSTIN
+ b)
&
External
Reset
Sources
a) Generated Warm Reset
b) Automatic Power-ON Reset
MCA04483
Figure 20-1 External Reset Circuitry
User’s Manual
20-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
20.1
Reset Sources
Several external or internal sources can generate a reset for the C164CM. Software can
identify the respective reset source via the reset source indication flags in register
WDTCON. Generally, any reset causes the same actions on the C164CM’s modules.
The differences are described in the following sections.
Hardware Reset
A hardware reset is triggered when the reset input signal RSTIN is latched low. To
ensure the recognition of the RSTIN signal (latching), it must be held low for at least
100 ns plus 2 CPU clock cycles (input filter plus synchronization). Shorter RSTIN pulses
may also trigger a hardware reset if they coincide with the latch’s sample point. The
actual minimum duration for a reset pulse depends on the current CPU clock generation
mode. The worst case is generating the CPU clock via the SlowDown Divider using the
maximum factor while the configured basic mode uses the prescaler (fCPU = fOSC / 64 in
this case).
After the reset sequence has been completed, the RSTIN input is sampled again. If the
reset input signal is inactive at that time, the internal reset condition is terminated
(indicated as short hardware reset, SHWR). If the reset input signal is still active at that
time, the internal reset condition is prolonged until RSTIN becomes inactive (indicated
as long hardware reset, LHWR).
During a hardware reset, the inputs for the reset configuration (PORT0, RD, ALE) need
some time to settle on the required levels, especially if the hardware reset aborts a read
operation from an external peripheral. During this settling time, the configuration may
intermittently be wrong. For the duration of one internal reset sequence after a reset has
been recognized, the configuration latches are not transparent; thus the (new)
configuration becomes valid earliest after the completion of one reset sequence. This
usually covers the required settling time.
When the basic clock is generated by the PLL, the internal reset condition is
automatically extended until the on-chip PLL has locked.
The input RSTIN provides an internal pull-up device equalling a resistor of 50 kΩ to
250 kΩ (the minimum reset time must be determined by the lowest value). Simply
connecting an external capacitor is sufficient for an automatic power-on reset (see b) in
Figure 20-1). RSTIN may also be connected to the output of other logic gates (see a) in
Figure 20-1). See also “Bidirectional Reset” on Page 22-4 in this case.
Note: A power-on reset requires an active time of two reset sequences (1036 CPU clock
cycles) after a stable clock signal is available (about 10 … 50 ms, depending on
the oscillator frequency, to allow the on-chip oscillator to stabilize).
User’s Manual
20-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
Software Reset
The reset sequence can be triggered at any time via the protected instruction SRST
(Software Reset). This instruction can be executed deliberately within a program, such
as to exit bootstrap loader mode, or upon a hardware trap that reveals a system failure.
Note: A software reset only latches the configuration of the bus interface (BUSTYP) from
PORT0 in case of an external reset.
If bidirectional reset is enabled, a software reset is executed like a long hardware
reset.
Watchdog Timer Reset
If the Watchdog Timer (WDT) is not disabled during the initialization or serviced regularly
during program execution, it will overflow and trigger the reset sequence. Other than
after hardware and software reset, the watchdog reset completes a running external bus
cycle. Then the internal reset sequence is started.
Note: A watchdog reset only latches the configuration of the bus interface (BUSTYP)
from PORT0 in case of an external reset.
If bidirectional reset is enabled, a watchdog timer reset is executed like a long
hardware reset.
The watchdog reset cannot occur while the C164CM is in bootstrap loader mode!
User’s Manual
20-3
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
Bidirectional Reset
In a special bidirectional reset mode, the C164CM’s line RSTIN (normally an input) may
be driven active by the chip logic. This is useful, for instance, to support external
equipment required for startup (such as flash memory).
RSTIN
Internal Circuitry
&
Reset Sequence Active
BDRSTEN = '1'
MCS04403
Figure 20-2 Bidirectional Reset Operation
Bidirectional reset reflects internal reset sources (software, watchdog) to the RSTIN pin
and converts short hardware reset pulses to a minimum duration of the internal reset
sequence. Bidirectional reset is enabled by setting bit BDRSTEN in register SYSCON;
it changes RSTIN from a pure input to an open drain IO line. When an internal reset is
triggered by the SRST instruction, by a watchdog timer overflow, or by a low level applied
to the RSTIN line, an internal driver pulls it low for the duration of the internal reset
sequence. After that, it is released and is then controlled solely by the external circuitry.
The bidirectional reset function is useful for applications in which external devices
require a defined reset signal but which cannot be connected to the C164CM’s RSTOUT
signal; for example, an external Flash memory which must come out of reset and deliver
code well before RSTOUT can be deactivated via EINIT.
The following behavior differences must be observed when using the bidirectional reset
feature in an application:
•
•
•
•
Bit BDRSTEN in register SYSCON cannot be changed after EINIT.
Bit BDRSTEN is cleared after a reset.
The reset indication flags always indicate a long hardware reset.
The PORT0 configuration is treated as on a hardware reset. Especially the bootstrap
loader may be activated when P0L.4 or RD is low.
• Pin RSTIN may only be connected to external reset devices with open drain output
driver.
• A short hardware reset is extended to the duration of the internal reset sequence.
User’s Manual
20-4
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C164CM/C164SM
Derivatives
System Reset
20.2
Status After Reset
Most units of the C164CM enter a well-defined default status after a reset is completed.
This ensures repeatable start conditions and avoids spurious activities after reset.
Watchdog Timer Operation after Reset
The watchdog timer starts running after the internal reset is complete. It will be clocked
with the internal system clock divided by 2 (fCPU / 2), and its default reload value is 00H.
Thus a watchdog timer overflow will occur 131,072 CPU clock cycles (2 × 216) after
completion of the internal reset, unless it is disabled, serviced, or reprogrammed in the
meantime. If the system reset was caused by a watchdog timer overflow, the WDTR
(Watchdog Timer Reset Indication) flag in register WDTCON will be set to ‘1’. This
indicates the cause of the internal reset to the software initialization routine. WDTR is
reset to ‘0’ by an external hardware reset, by servicing the watchdog timer or after EINIT.
After the internal reset is complete, the operation of the watchdog timer can be disabled
by the DISWDT (Disable Watchdog Timer) instruction. This instruction has been
implemented as a protected instruction. For further security, its execution is enabled only
in the time period after a reset until either the SRVWDT (Service Watchdog Timer) or the
EINIT instruction has been executed. Thereafter, the DISWDT instruction will have no
effect.
Reset Values for the C164CM Registers
During the reset sequence, the registers of the C164CM are preset with a default value.
Most SFRs, including system registers and peripheral control and data registers, are
cleared to zero, so all peripherals and the interrupt system are off or idle after reset. A
few exceptions to this rule provide a first pre-initialization, which is either fixed or
controlled by input pins.
DPP1:
DPP2:
DPP3:
CP:
STKUN:
STKOV:
SP:
WDTCON:
S0RBUF:
SSCRB:
SYSCON:
BUSCON0:
RP0H:
ONES:
User’s Manual
0001H (points to data page 1)
0002H (points to data page 2)
0003H (points to data page 3)
FC00H
FC00H
FA00H
FC00H
00XXH (value depends on the reset source)
XXH (undefined)
XXXXH (undefined)
0XX0H (set according to reset configuration)
0XX0H (set according to reset configuration)
XXH (reset levels of P0H)
FFFFH (fixed value)
20-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
The C164CM’s Pins after Reset
After the reset sequence, the various groups of pins of the C164CM are activated in
different ways depending on their function. Bus and control signals are activated
immediately after the reset sequence according to the configuration latched from
PORT0, so either external accesses can take place or the external control signals will be
inactive. The general purpose IO pins remain in input mode (high impedance) until
reprogrammed via software (see Figure 20-3). The RSTOUT pin remains active (low)
until the end of the initialization routine (see description).
8)
6)
RSTIN
7)
RD, WR
ALE
Bus
1)
IO
2)
RSTOUT
2)
4)
3)
Internal Reset Condition
5)
Initialization
3)
6)
RSTIN
Internal Reset Condition
Initialization
When the internal reset condition is extended by RSTIN, the activation of the output signals is
delayed until the end of the internal reset condition.
1)
2)
3)
4)
5)
6)
7)
8)
Current bus cycle is completed or aborted.
Switches asinchronously with RSTIN, sinchronously upon software or watchdog reset.
The reset condition ends here. The C 167CR starts program execution.
Activation of the IO pins is controlled by software.
Execution of the EINIT instruction.
The shaded area designates the internal reset sequence, which starts after synchronization of RSTIN.
A short hardware reset is extended until the end of the reset sequence in Bidirectional reset mode.
A software or WDT reset activates the RSTIN line in Bidirectional reset mode.
MCS02258
Figure 20-3 Reset Input and Output Signals
User’s Manual
20-6
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
Ports and External Bus Configuration during Reset
During the internal reset sequence, all port pins of the C164CM are configured as inputs
by clearing the associated direction registers, and their pin drivers are switched to the
high impedance state. This ensures that the C164CM and external devices will not try to
drive the same pin to different levels. Pin ALE is held low through an internal pull-down,
and pins RD and WR are held high through internal pull-ups.
The registers SYSCON and BUSCON0 are initialized according to the configuration
selected via PORT0.
When an external start is selected (pin EA = ‘0’):
• Bus Type field (BTYP) in register BUSCON0 is initialized according to
P0L.7 and P0L.6
• Bit BUSACT0 in register BUSCON0 is set to ‘1’
• Bit ALECTL0 in register BUSCON0 is set to ‘1’
• Bit ROMEN in register SYSCON will be cleared to ‘0’
When an internal start is selected (pin EA = ‘1’):
• Register BUSCON0 is initialized to 00C0H
• Bit ROMEN in register SYSCON will be set to ‘1’
The other bits of register BUSCON0, and the other BUSCON registers are cleared.
This default initialization selects the slowest possible external accesses using the
configured bus type.
When the internal reset is complete, the configuration of PORT0 and PORT1 depends
on the bus type selected during reset. If any of the external bus modes was selected
during reset, PORT0 will operate in the selected bus mode.
When the on-chip bootstrap loader was activated during reset, pin TxD0 (alternate port
function) will be switched to output mode after the reception of the zero byte.
All other pins remain in the high-impedance state until they are changed by software or
peripheral operation.
Note: If Port 20 operation is selected after reset (by pulling pin WR low during an internal
reset with EA = ‘1’) pins RD, WR, and ALE switch to input when the internal reset
is complete.
User’s Manual
20-7
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
Reset Output Pin
The RSTOUT pin generates a reset signal for the system components other than the
controller. RSTOUT will be driven active (low) at the begin of any reset sequence
(triggered by hardware, the SRST instruction, or a watchdog timer overflow). RSTOUT
stays active (low) beyond the end of the internal reset sequence until the protected EINIT
(End of Initialization) instruction is executed (see Figure 20-3). This allows the complete
configuration of the controller including its on-chip peripheral units before releasing the
reset signal for the external peripherals of the system.
Note: RSTOUT remains active low when Port 20 is initially enabled. The output level can
be changed to high, or the pin can be switched to input via the port control
registers P20 and DP20.
RSTOUT will float during emulation mode or adapt mode.
The Internal RAM after Reset
The contents of the internal RAM are not affected by a system reset. However, after a
power-on reset, the contents of the internal RAM are undefined. This implies that the
GPRs (R15 … R0) and the PEC source and destination pointers (SRCP7 … SRCP0,
DSTP7 … DSTP0) which are mapped into the internal RAM are also unchanged after a
warm reset, software reset, or watchdog reset, but are undefined after a power-on reset.
Operation after Reset
After the internal reset condition is removed, the C164CM fetches the first instruction
from the program memory (location 00’0000H for a standard start). As a rule, this first
location holds a branch instruction to the actual initialization routine that may be located
anywhere in the address space.
Note: If the Bootstrap Loader Mode was activated during a hardware reset, the C164CM
does not fetch instructions from the program memory.
The standard bootstrap loader expects data via serial interface ASC0.
User’s Manual
20-8
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
20.3
Application-Specific Initialization Routine
After a reset, the modules of the C164CM must be initialized to enable their operation on
a given application. This initialization depends on the task to be performed by the
C164CM in that application and on some system properties such as operating
frequency, external circuitry connected, etc.
Typically, the following initializations should be done before the C164CM is prepared to
run the actual application software:
Memory Areas
The external bus interface can be reconfigured after an external reset because register
BUSCON0 is initialized to the slowest possible bus cycle configuration. The
programmable address windows can be enabled in order to adapt the bus cycle
characteristics to various memory areas or peripherals. Also, after a single-chip mode
reset, the external bus interface can be enabled and configured.
The internal program memory (if available) can be enabled and mapped after an
external reset in order to use the on-chip resources. After a single-chip mode reset, the
internal program memory can be remapped or disabled in order to utilize external
memory (partially or completely).
Programmable program memory can be programmed, for instance, with data received
over a serial link.
Note: Initial Flash or OTP programming will rather be done in bootstrap loader mode.
System Stack
The default setup for the system stack (size, stackpointer, upper and lower limit
registers) can be adjusted to application-specific values. After reset, registers SP and
STKUN contain the same reset value 00’FC00H, while register STKOV contains
00’FA00H. With the default reset initialization, 256 words of system stack are available,
where the system stack selected by the SP grows downwards from 00’FBFEH.
Note: The interrupt system, which is disabled upon completion of the internal reset,
should remain disabled until the SP is initialized.
Traps (including NMI) may occur, although the interrupt system is still disabled.
Register Bank
The location of a register bank is defined by the context pointer (CP) and can be adjusted
to an application-specific bank before the general purpose registers (GPRs) are used.
After reset, register CP contains the value 00’FC00H, i.e. the register bank selected by
the CP grows upward from 00’FC00H.
User’s Manual
20-9
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
On-Chip RAM
Depending on the application, the user may wish to initialize portions of the internal
writable memory (IRAM) before normal program operation. After the register bank has
been selected by programming the CP register, the desired portions of the internal
memory can easily be initialized via indirect addressing.
Interrupt System
After reset, the individual interrupt nodes and the global interrupt system are disabled. In
order to enable interrupt requests, the nodes must be assigned to their respective
interrupt priority levels and must be enabled. The vector locations must receive pointers
to the respective exception handlers. The interrupt system must globally be enabled by
setting bit IEN in register PSW. To avoid such problems as the corruption of internal
memory locations caused by stack operations using an uninitialized stack pointer, care
must be taken not to enable the interrupt system before the initialization is complete.
Watchdog Timer
After reset, the watchdog timer is active and counting its default period. If the watchdog
timer is to remain active the desired period should be programmed by selecting the
appropriate prescaler value and reload value. Otherwise, the watchdog timer must be
disabled before EINIT.
Ports
Generally, all ports of the C164CM are switched to input after reset. Some pins may be
automatically controlled, such as bus interface pins for an external start, TxD in Boot
mode, etc. Pins to be used for general purpose IO must be initialized via software. The
required mode (input/output, open drain/push pull, etc.) depends on the intended
function for a given pin.
Peripherals
After reset the C164CM’s on-chip peripheral modules enter a defined default state (see
respective peripheral description) in which they are disabled from operation. In order to
use a certain peripheral it must be initialized according to its intended operation in the
application.
This includes selecting the operating mode (such as counter/timer), operating
parameters (such as baudrate), enabling interface pins (if required), assigning interrupt
nodes to the respective priority levels, etc.
After these standard initialization actions, application-specific actions may be required,
such as asserting certain levels to output pins, sending codes via interfaces, latching
input levels, etc.
User’s Manual
20-10
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
Termination of Initialization
The software initialization routine should be terminated with the EINIT instruction. This
instruction has been implemented as a protected instruction.
Execution of the EINIT instruction has the following effects:
• Disables the action of the DISWDT instruction,
• Disables write accesses to register SYSCON (all configurations regarding register
SYSCON (enable CLKOUT, stacksize, etc.) must be selected before the execution of
EINIT),
• Disables write accesses to registers SYSCON2 and SYSCON3
(further write accesses to SYSCON2 and SYSCON3 can be executed only using a
special unlock mechanism),
• Clears the reset source detection bits in register WDTCON,
• Causes the RSTOUT pin to go high
(this signal can be used to indicate the end of the initialization routine and the proper
operation of the microcontroller to external hardware).
User’s Manual
20-11
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
20.4
System Startup Configuration
Although most of the programmable features of the C164CM are selected by software
either during the initialization phase or repeatedly during program execution, some
features must be selected earlier because they are used for the first access of the
program execution (for example, internal or external start selected via EA).
These configurations are accomplished by latching the logic levels at a number of pins
at the end of the internal reset sequence. During reset, internal pull-up/pull-down devices
are active on those lines. They ensure inactive/default levels at pins which are not driven
externally. External pull-down/pull-up devices may override the default levels in order to
select a specific configuration. Many configurations can, therefore, be coded with a
minimum of external circuitry.
Note: The load on those pins to be latched for configuration must be small enough for
the internal pull-up/pull-down device to sustain the default level, or external pullup/pull-down devices must ensure this level.
Those pins whose default level will be overridden must be pulled low/high
externally.
Ensure that the valid target levels are reached by the end of the reset sequence.
There is a specific application note to illustrate this.
User’s Manual
20-12
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
20.4.1
System Startup Configuration upon an External Reset
For an external reset (EA = ‘0’), the startup configuration uses the pins of PORT0 and
pins RD and WR. The value on the upper byte of PORT0 (P0H) is latched into register
RP0H upon reset, the value on the lower byte (P0L) directly influences the BUSCON0
register (bus mode) or the internal control logic of the C164CM.
H.7
H.6
H.5
H.4
H.3
H.2
H.1
L.7
L.6
BUSTYP
L.5
L.4
L.3
L.2
R
BSL
R
R
RP0H
CLKCFG
H.0
L.1
L.0
ADP EMU
Internal Control Logic
(only on Hardware Reset)
Clock
Generator
SYSCON
RD
BUSCON0
WR
MCA05130
Figure 20-4 PORT0 Configuration during Reset
The pins which control operation of the internal control logic, the clock configuration, and
the reserved pins are evaluated only during a hardware triggered reset sequence. The
pins which influence the configuration of the C164CM are evaluated during any reset
sequence, including software and watchdog timer triggered resets.
The configuration via P0H is latched in register RP0H for subsequent evaluation by
software. Register RP0H is described in Chapter 9.
Note: Pin P0H.0 must be held high upon an external reset.
The following descriptions refer to the various selections available for reset
configuration. The default modes refer to pins at high level without external pull-down
devices connected.
Please also consider the note above.
User’s Manual
20-13
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
Emulation Mode
Pin P0L.0 (EMU) selects the Emulation Mode when latched low at the end of reset.
Because this mode is used for special emulation and testing purposes and is of minor
use for standard C164CM applications, P0L.0 should be held high.
Emulation Mode provides access to integrated XBUS peripherals via the external bus
interface pins (direction reversed) of the C164CM. The CPU and the generic peripherals
are disabled, all modules connected via the XBUS are active. Ensure that all required
input pins are driven accordingly (see Table 20-1) and no driver conflicts exist on the
respective output pins.
The other pins retain their original function or are unused. Unused pins are switched to
input and should be pulled to a stable level to avoid switching noise.
Table 20-1
Emulation Mode Summary
Pin(s)
Function
Notes
PORT0
Data input/output
–
PORT1
Address input
–
NMI
XBHE
Must be driven externally, can be kept low
P20.0
RD
Control signal input
P20.1
WR
Control signal input
P20.4
ALE input (unused)
Hold LOW
RSTOUT
Reset input
Drive externally for an XBUS peripheral reset
RSTIN
Reset input
Standard reset for complete device
P5.1
CSCAN input
Enables module CAN1 in emulation mode
P20.8
CLKOUT
Automatically enabled
Port 8
XBUS peripheral
interrupt output
P8.0:
P8.1:
P8.2:
P8.3:
CAN1
not used, always High
not used, always High
PLL
Default: Emulation Mode is off.
Note: In emulation mode pin P0.15 (P0H.7) is inverted, i.e. the configuration ‘111’ would
select direct drive in emulation mode.
Emulation mode can only be activated upon an external reset (EA = ‘0’). Pin P0L.0
is not evaluated upon a single-chip reset (EA = ‘1’).
User’s Manual
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V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
Adapt Mode
Pin P0L.1 (ADP) selects the Adapt Mode when latched low at the end of reset. In this
mode, the C164CM goes into a passive state similar to its state during reset. The pins of
the C164CM float to tristate or are deactivated via internal pull-up/pull-down devices, as
described for the reset state. Additionally, the RSTOUT pin floats to tristate rather than
being driven low. The on-chip oscillator and the realtime clock are disabled.
This mode allows a C164CM mounted to a board to be virtually switched off. This
enables an emulator to control the board’s circuitry even though the original C164CM
remains in place. The original C164CM may resume control of the board after a reset
sequence with P0L.1 high. Please note that adapt mode overrides any other
configuration via PORT0.
Default: Adapt Mode is off.
Note: When XTAL1 is fed by an external clock generator (while XTAL2 is left open), this
clock signal may also be used to drive the emulator device.
However, if a crystal is used, the emulator device’s oscillator can use this crystal
only if at least XTAL2 of the original device is disconnected from the circuitry (the
output XTAL2 will be driven high in Adapt Mode).
Adapt mode can be activated only upon an external reset (EA = ‘0’). Pin P0L.1 is
not evaluated upon a single-chip reset (EA = ‘1’).
User’s Manual
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C164CM/C164SM
Derivatives
System Reset
Special Operation Modes
Pins P0L.5 to P0L.2 (SMOD) select special operation modes of the C164CM during reset
(see Table 20-2). Make sure to select only valid configurations to ensure proper
operation of the C164CM.
Table 20-2
Definition of Special Modes for Reset Configuration
P0.5-2 (P0L.5-2)
Special Mode
Notes
1 1 1 1
Normal Start
Default configuration.
Begin of execution as defined via pin EA.
1 1 1 0
CPU Host Mode
(CHM)
Programming mode for OTP memory via the
C164CM’s CPU.
1 1 0 1
Reserved
Do not select this configuration!
1 1 0 0
Reserved
Do not select this configuration!
1 0 1 1
Standard Bootstrap
Loader
Load an initial boot routine of 32 Bytes via
interface ASC0.
1 0 1 0
Bootstrap Loader
+ CPU Host Mode
Serial programming of OTP memory via
ASC0 using the bootstrap loader.
1 0 0 1
Alternate Boot
Operation not yet defined. Do not use!
1 0 0 0
Reserved
Do not select this configuration!
0 1 1 1
No emulation mode: Operation not yet defined. Do not use!
Alternate Start
Emulation mode:
Programming mode for OTP memory via
External Host Mode external host.
(EHM)
0 1 1 0
Reserved
Do not select this configuration!
0 1 0 1
Reserved
Do not select this configuration!
0 1 0 0
Reserved
Do not select this configuration!
0 0 X X
Reserved
Do not select this configuration!
The On-Chip Bootstrap Loader allows the start code to be moved into the internal RAM
of the C164CM via the serial interface ASC0. The C164CM will remain in bootstrap
loader mode until a hardware reset deselects BSL mode or until a software reset.
Default: The C164CM starts fetching code from location 00’0000H, the bootstrap loader
is off.
User’s Manual
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C164CM/C164SM
Derivatives
System Reset
External Bus Type
Pins P0L.7 and P0L.6 (BUSTYP) select the external bus type during reset, if an external
start is selected via pin EA. This allows configuration of the external bus interface of the
C164CM even for the first code fetch after reset. The two bits are copied into bit field
BTYP of register BUSCON0. P0L.7 controls the data bus width, while P0L.6 controls the
address output (multiplexed or demultiplexed). This bit field may be changed via
software after reset, if required.
Table 20-3
Configuration of External Bus Type
P0L.7-6 (BTYP)
Encoding
External Data Bus Width
External Address Bus Mode
00
8-bit Data
Demultiplexed Addresses
01
8-bit Data
Multiplexed Addresses
10
16-bit Data
Demultiplexed Addresses
11
16-bit Data
Multiplexed Addresses
PORT0 and PORT1 are automatically switched to the selected bus mode. In multiplexed
bus modes, PORT0 drives both the 16-bit intra-segment address and the output data,
while PORT1 remains in high impedance state as long as no demultiplexed bus is
selected via one of the BUSCON registers. In demultiplexed bus modes, PORT1 drives
the 16-bit intra-segment address, while PORT0 or P0L (according to the selected data
bus width) drives the output data.
Default: 16-bit data bus with multiplexed addresses.
Note: If an internal start is selected via pin EA, these two pins are disregarded and bit
field BTYP of register BUSCON0 is cleared.
For most non-single-chip applications 8-bit multiplexed bus mode will be the best
tradeoff between on-chip peripheral functionality and external bus operation.
User’s Manual
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V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
Clock Generation Control
Pins P0H.7, P0H.6 and P0H.5 (CLKCFG) select the basic clock generation mode during
reset. The oscillator clock either directly feeds the CPU and peripherals (direct drive), is
divided by 2 or is fed to the on-chip PLL which then provides the CPU clock signal
(selectable multiple of the oscillator frequency, i.e. the input frequency). These bits are
latched in register RP0H.
Table 20-4
C164CM Clock Generation Modes
(P0H.7-5)
(CLKCFG)
CPU Frequency
fCPU = fOSC × F
External Clock
Input Range1)
Notes
1 1 1
fOSC × 4
fOSC × 3
fOSC × 2
fOSC × 5
fOSC × 1
fOSC × 1.5
fOSC / 2
fOSC × 2.5
2.5 to 6.25 MHz
Default configuration
3.33 to 8.33 MHz
–
5 to 12.5 MHz
–
2 to 5 MHz
–
1 to 25 MHz
Direct drive2)
6.66 to 16.6 MHz
–
2 to 50 MHz
CPU clock via prescaler
4 to 10 MHz
–
1 1 0
1 0 1
1 0 0
0 1 1
0 1 0
0 0 1
0 0 0
1)
The external clock input range refers to a CPU clock range of 10
2)
The maximum frequency depends on the duty cycle of the external clock signal.
In emulation mode pin P0.15 (P0H.7) is inverted, i.e. the configuration ‘111’ would select direct drive in
emulation mode.
… 25 MHz.
Default: On-chip PLL is active with a factor of 1:4.
Watch the different requirements for frequency and duty cycle of the oscillator input clock
for the possible selections.
Oscillator Watchdog Control
The on-chip oscillator watchdog (OWD) may be disabled via hardware by (externally)
pulling the RD line low upon a reset, similar to the standard reset configuration via
PORT0. At the end of an external reset, bit OWDDIS in register SYSCON reflects the
inverted level of pin RD at that time. The software may again enable the oscillator
watchdog by clearing bit OWDDIS before the execution of EINIT.
Note: If direct drive or prescaler operation is selected as basic clock generation mode
(see above) the PLL is switched off whenever bit OWDDIS is set (via software or
via hardware configuration).
User’s Manual
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C164CM/C164SM
Derivatives
System Reset
20.4.2
System Startup Configuration at Single-Chip Mode Reset
For a single-chip mode reset (indicated by EA = ‘1’) the configuration via PORT0 is
replaced by a fixed configuration value. In this case, PORT0 needs no external circuitry
(pull-ups/pull-downs) and also the internal configuration pull-ups are not activated.
The necessary startup modes are configured via pins RD and ALE. The operating mode
for Port 20 pins can be configured via pin WR which is not necessarily used in singlechip mode.
This fixed default configuration is activated after each Long Hardware Reset and selects
a safe worst-case configuration. The initialization software can then modify these
parameters and select the intended configuration for a given application. Table 20-5 lists
the respective default configuration values which are selected and the bitfields which
permit software modification.
Table 20-5
Default Configuration for Single-Chip Mode Reset
External
Config.1)
Configuration
Parameter
Default Values
(RP0H = XX2DH)
CLKCFG: Generation
mode of basic clock
‘001’ = Prescaler operation, P0.15-13
i.e. fCPU = fOSC / 2
BTYP: Default bustype BUSCON0.BTYP = ‘11’
(BUSCON0)
i.e. 16-bit MUX bus
P0.7-6
Software Access2)
RSTCON.15-13
BUSCON0.BTYP
SMOD: Special modes Startup modes selected via P0.5-2
(start/boot modes)
pins RD and ALE
–
ADP: Adapt Mode
Not possible
P0.1
–
EMU: Emulation Mode
Not possible
P0.0
–
OWD disable
SYSCON.OWDDIS = ‘0’
i.e. OWD is active
RD
SYSCON.OWDDIS
Port 20 enable
Port 20 mode selected via
pin WR
–
SYSCON.P20EN
1)
Refers to the configuration pins which are replaced by the default values.
2)
Software can modify the default values via these bitfields.
Note: Single-chip mode reset cannot be selected on ROMless devices. The attempt to
read the first instruction after reset will fail in such a case.
User’s Manual
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C164CM/C164SM
Derivatives
System Reset
Single-Chip Startup Modes
The startup mode (operation after reset) of the C164CM can be configured during reset.
In single-chip mode this configuration is selected via pins RD and ALE.
Pin RD selects start or boot mode (instead of OWD control), pin ALE selects one of two
alternatives in each case.
Table 20-6
Startup Mode Configuration in Single-Chip Reset Mode
RD
ALE
Startup Mode
Notes
1
0
Standard Start
Execution starts at user memory location
00’0000H.
1
1
Alternate Start
Operation not yet defined. Do not use!
0
0
Standard Bootstrap
Loader
Load 32 bytes via ASC0.
0
1
Alternate Boot Mode
Operation not defined. Do not use!
Pin WR additionally selects the initial operating mode of the Port 20 pins.
Table 20-7
Initial Port 20 Mode Configuration in Single-Chip Reset Mode
WR
Port 20 Mode
1
Software may enable and use the external
Port 20 is disabled, the
respective pins retain their bus interface at any time
alternate functions
0
This corresponds to an active write signal
Port 20 is enabled1), the
respective pins switch to
and indicates that no external system is
input (except for RSTOUT) present.2)
Notes
1)
In all other cases Port 20 remains disabled after reset.
2)
Care must be taken if designing an external read-only system (e.g. EPROM), where the active write signal
does not conflict with the system. A pull-up may be required for the output enable signal.
Note: Startup mode configuration and Port 20 mode configuration are independent of
each other.
User’s Manual
20-20
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C164CM/C164SM
Derivatives
System Reset
20.5
System Configuration via Software
The system configuration selected via hardware after reset (latched pin levels or default
value) can be changed via software by executing a specific code sequence. The
respective control bits are located within registers SYSCON, BUSCONx, and RSTCON.
Register SYSCON can be modified only before the execution of instruction EINIT, while
registers BUSCONx and RSTCON (using the specific sequence) can be modified
repeatedly at any time.
The clock generation mode (CLKCFG) is controlled by register RP0H. RP0H is initialized
according to the selected reset mode (pins or default). The respective configuration
bitfields can be copied from register RSTCON upon entering Slow Down Divider mode
if enabled by bit SUE = ‘1’.
The following steps must be taken to change the current configuration (see software
example as well):
• Write intended configuration value to RSTCON
• Enter SDD mode
• Return to basic clock mode
CHANGE_CLOCK_CONFIGURATION:
MOV R15, #11100001xxxxxxxxB
MOV RSTCON, R15
EXTR #2
MOV SYSCON2, #0100H
MOV SYSCON2, #0400H
;“RSTCON” is a mem address, no SFR
;Load a GPR with the target value
;Enable update with PLL factor 4
;ESFR-access to SYSCON2
;SDD mode, PLL on, factor 1
;RSTCON.15-9 is copied to RP0H.15-9
;Switch to basic clock mode
;System will run on PLL (factor 4)..
;..after PLL has locked
Note: This software example assumes execution before EINIT. Otherwise, the unlock
sequence must be executed prior to each access to RSTCON/SYSCON2.
Entering SDD mode temporarily ensures a correct clock signal synchronization in cases
where the clock generation mode is changed (PLL factor, for example). If the target basic
clock generation mode uses the PLL, the C164CM will run in direct-drive mode until the
PLL has locked.
Software modification of system configuration values is protected by the following
features:
• SYSCON is locked after EINIT
• RSTCON requires the unlock sequence after EINIT
• Copying RSTCON to RP0H must be explicitly enabled by setting bit SUE
User’s Manual
20-21
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Reset
RSTCON
Reset Control Register
15
14
13
12
11
mem (F1E0H/--)
10
9
Reset Value: 00XXH
8
7
6
5
4
3
2
1
0
CLKCFG
-
-
SUE
-
-
-
-
-
-
RSTLEN
rw
r-
-
rw
-
-
-
-
-
-
rw
Bit
Function
RSTLEN
Reset Length Control (duration of the next reset sequence to occur)1)
00: 1024 TCL: standard duration,
corresponds to all other derivatives without control function
01: 2048 TCL: extended duration,
may be useful, for example, to provide additional settling for
external configuration signals at high CPU clock frequencies
10: Reserved
11: Reserved
SUE
Software Update Enable
0:
Configuration cannot be changed via software
1:
Software update of configuration is enabled
CLKCFG
Clock Generation Mode Configuration
These pins define the clock generation mode, i.e. the mechanism by
which the internal CPU clock is generated from the externally applied
(XTAL1) input clock.
000: PLL (f × 2.5)
100: PLL (f × 5)
001: Prescaler (f / 2)
101: PLL (f × 2)
110: PLL (f × 3)
010: PLL (f × 1.5)
011: Direct Drive (f = f)
111: PLL (f × 4)
1)
RSTLEN is always valid for the next reset sequence. An initial power up reset, however, is expected to last
considerably longer than any configurable reset sequence.
Note: RSTCON is write protected after the execution of EINIT unless it is released via
the unlock sequence (see Section 21.7).
RSTCON can be accessed only via its long (mem) address.
User’s Manual
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Derivatives
Power Management
21
Power Management
An increasingly important objective for microcontroller-based systems is the significant
reduction of power consumption. A contradictory objective is to reach a certain level of
system performance. Besides optimization of design and technology, a microcontroller’s
power consumption can generally be reduced by lowering its operating frequency and/
or by reducing the clocked circuitry. The architecture of the C164CM provides three
major means of reducing its power consumption under software control (see
Figure 21-1):
• Reduction of the CPU frequency for Slow Down operation
(Flexible Clock Generation Management)
• Selection of the active peripheral modules
(Flexible Peripheral Management)
• Special operating modes to deactivate CPU, ports, and control logic
(Idle, Sleep, Power Down)
This enables the application (i.e. the programmer) to choose the optimum constellation
for each operating condition, so the power consumption can be adapted to conditions
like maximum performance, partial performance, intermittent operation or standby.
User’s Manual
21-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
Power
ive
t
Ac
Active
e
Idl
Idle
n
r
we
Po
w
Do
No. of act.
Peripherals
fCPU
MCA04476
Figure 21-1 Power Reduction Possibilities
Intermittent operation (alternating phases of high performance and power saving) is
supported by the cyclic interrupt generation mode of the on-chip RTC (Real Time Clock).
These three power reduction possibilities described above can be applied independently
from each other and thus provide a maximum flexibility for each application.
For the basic power reduction modes (Idle, Power Down) there are dedicated
instructions, while special registers control Sleep mode (SYSCON1), clock generation
(SYSCON2), and peripheral management (SYSCON3).
Three different general power reduction modes with different levels of power reduction
have been implemented in the C164CM. They may be entered under software control:
In Idle Mode, the CPU is stopped while the (enabled) peripherals continue their
operation. Idle mode can be terminated by any reset or interrupt request.
In Sleep Mode, both the CPU and the peripherals are stopped. The real-time clock and
its selected oscillator may optionally be kept running. Sleep mode can be terminated by
any reset or interrupt request (mainly hardware requests as stopped peripherals cannot
generate interrupt requests).
User’s Manual
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Derivatives
Power Management
In Power Down Mode, both the CPU and the peripherals are stopped. The real time
clock and its selected oscillator may optionally be kept running. Power Down mode can
be terminated by a hardware reset only.
Note: All external bus actions are completed before a power saving mode is entered.
In addition the power management selects the current CPU frequency and controls
which peripherals are active.
During Slow Down Operation, the basic clock generation path is bypassed and the
CPU clock is generated via the programmable Slow Down Divider (SDD) from the
selected oscillator clock signal.
Peripheral Management disables and enables the on-chip peripheral modules
independently, reducing the amount of clocked circuitry (including the associated clock
drivers).
User’s Manual
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V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
21.1
Idle Mode
Power consumption of the C164CM microcontroller can be decreased by entering Idle
mode. In this mode, all enabled peripherals continue to operate normally, including the
watchdog timer; only the CPU operation is halted and the on-chip memory modules are
disabled.
Note: Peripherals that have been disabled via software also remain disabled after
entering Idle mode.
Idle mode is entered after the IDLE instruction has been executed and the instruction
before the IDLE instruction has been completed (bitfield SLEEPCON in register
SYSCON1 must be ‘00B’). To prevent unintentionally entering Idle mode, the IDLE
instruction has been implemented as a protected 32-bit instruction.
Idle mode is terminated by interrupt requests from any enabled interrupt source whose
individual Interrupt Enable flag was set before the Idle mode was entered, regardless of
bit IEN.
For a request selected for CPU interrupt service, the associated interrupt service routine
is entered if the priority level of the requesting source is higher than the current CPU
priority and the interrupt system is globally enabled. After the RETI (Return from
Interrupt) instruction of the interrupt service routine is executed, the CPU continues
executing the program with the instruction following the IDLE instruction. If the interrupt
request cannot be serviced because the priority is too low or the interrupt system is
globally disabled, the CPU immediately resumes normal program execution with the
instruction following the IDLE instruction.
For a request programmed for PEC service, a PEC data transfer is performed if the
priority level of this request is higher than the current CPU priority and the interrupt
system is globally enabled. After the PEC data transfer has been completed, the CPU
remains in Idle mode. If the PEC request cannot be serviced because the priority is too
low or the interrupt system is globally disabled, the CPU does not remain in Idle mode
but continues program execution with the instruction following the IDLE instruction.
User’s Manual
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V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
Denied
CPU Interrupt Request
Accepted
Active
Mode
IDLE Instruction
Idle
Mode
Denied PEC Request
Executed
PEC Request
MCA04407
Figure 21-2 Transitions between Idle Mode and Active Mode
Idle mode can also be terminated by a Non-Maskable Interrupt, i.e. a high to low
transition on the NMI pin. After Idle mode has been terminated by an interrupt or NMI
request, the interrupt system performs a round of prioritization to determine the highest
priority request. In the case of an NMI request, the NMI trap will always be entered.
Any interrupt request whose individual Interrupt Enable flag was set before Idle mode
was entered will terminate Idle mode regardless of the current CPU priority. The CPU
will not go back into Idle mode when a CPU interrupt request is detected, even when the
interrupt was not serviced because of a higher CPU priority or a globally disabled
interrupt system (IEN = ‘0’). The CPU will only go back into Idle mode when the interrupt
system is globally enabled (IEN = ‘1’) and a PEC service on a priority level higher than
the current CPU level is requested and executed.
Note: An individually enabled interrupt request assigned to priority level 0 will terminate
Idle mode. The associated interrupt vector will not be accessed, however.
The watchdog timer may be used to monitor the Idle mode: an internal reset will be
generated if no interrupt or NMI request occurs before the watchdog timer overflows. To
prevent the watchdog timer from overflowing during Idle mode, it must be programmed
to a reasonable time interval before Idle mode is entered.
User’s Manual
21-5
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C164CM/C164SM
Derivatives
Power Management
21.2
Sleep Mode
To further reduce power consumption, the microcontroller can be switched to Sleep
mode. Clocking of all internal blocks is stopped (RTC and selected oscillator optionally).
The contents of the internal RAM, however, are preserved through the voltage supplied
via the VDD pins. The watchdog timer is stopped in Sleep mode.
Sleep mode is selected via bitfield SLEEPCON in register SYSCON1 and is entered
after the IDLE instruction has been executed and the instruction before the IDLE
instruction has been completed.
Sleep mode is terminated by interrupt requests from any enabled interrupt source whose
individual Interrupt Enable flag was set before the Idle mode was entered, regardless of
bit IEN. These are primarily external interrupts and the RTC (if running).
Note: The receive lines of serial interfaces may be internally routed to external interrupt
inputs (see EXISEL). All peripherals except for the RTC are stopped and hence
cannot generate an interrupt request.
The realtime clock (RTC) can be kept running in Sleep mode in order to maintain a valid
system time as long as the supply voltage is applied. This enables a system to determine
the current time and the duration of the period in Sleep mode (by comparing the current
time with a timestamp stored when Sleep mode was entered). The supply current in this
case remains well below 1 mA.
During Sleep mode, the voltage at the VDD pins can be lowered to 2.7 V while the RTC
and its selected oscillator will continue running and the contents of the internal RAM will
be preserved. With the RTC (and oscillator) disabled the internal RAM is preserved down
to a voltage of 2.5 V.
Note: When the RTC remains active in Sleep mode, the oscillator which generates the
RTC clock signal will also continue running.
If the supply voltage is reduced, the specified maximum CPU clock frequency for
this case must be taken into account.
For wakeup (input edge recognition and CPU start) the power level must be within
the specified limits.
The total power consumption in Sleep mode depends on the active circuitry (whether the
RTC is on or off) and on the current flowing through the port drivers. Individual port
drivers can be disabled simply by configuring them for input.
The bus interface pins can be separately disabled by releasing the external bus (disable
all address windows by clearing the BUSACT bits) and switching the ports to input (if
necessary). The required software in this case must be executed from internal memory.
User’s Manual
21-6
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
SYSCON1
System Control Reg.1
ESFR (F1DCH/EEH)
Reset Value: 0000H
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
-
-
-
-
-
-
-
-
-
-
-
-
-
-
SLEEP
CON
-
-
-
-
-
-
-
-
-
-
-
-
-
-
rw
Bit
Function
SLEEPCON
SLEEP Mode Configuration (mode entered upon the IDLE instruction)
00: Normal IDLE mode
01: SLEEP mode, with RTC running
10: Reserved.
11: SLEEP mode, with RTC and oscillator stopped
Note: SYSCON1 is write protected after the execution of EINIT unless it is released via
the unlock sequence (see Table 21-6).
21.3
Power Down Mode
The microcontroller can be switched to Power Down mode to reduce the power
consumption to a minimum. Clocking of all internal blocks is stopped (RTC and oscillator
optionally); but, the contents of the internal RAM are preserved through the voltage
supplied via the VDD pins. The watchdog timer is stopped in Power Down mode. This
mode can be terminated by an external hardware reset only (by asserting low level on
the RSTIN pin). This reset will initialize all SFRs and ports to their default state, but will
not change the contents of the internal RAM.
There are two levels of protection against unintentionally entering Power Down mode.
First, the PWRDN (Power Down) instruction used to enter this mode has been
implemented as a protected 32-bit instruction. Second, this instruction is effective only
if the NMI (Non Maskable Interrupt) pin is externally pulled low while the PWRDN
instruction is executed. The microcontroller will enter Power Down mode after the
PWRDN instruction is completed.
This feature can be used in conjunction with an external power failure signal which pulls
the NMI pin low when a power failure is imminent. The microcontroller will enter the NMI
trap routine which can save the internal state into RAM. After the internal state has been
saved, the trap routine may then execute the PWRDN instruction. If the NMI pin is still
low at this time, Power Down mode will be entered; otherwise, program execution
continues.
The initialization routine (executed upon reset) can check the reset identification flags in
register WDTCON to determine whether the controller was initially switched on, or
whether it was properly restarted from Power Down mode.
User’s Manual
21-7
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
If the supply voltage continues to be applied, the realtime clock (RTC) can be kept
running in Power Down mode to maintain a valid system time. This enables a system to
determine the current time and the duration of the period in Power Down mode (by
comparing the current time with a timestamp stored when Power Down mode was
entered). The supply current in this case remains well below 1 mA.
During power down, the voltage at the VDD pins can be lowered to 2.7 V while the RTC
and its selected oscillator continue running and the contents of the internal RAM will be
preserved.
With the RTC (and oscillator) disabled, the internal RAM is preserved down to a voltage
of 2.5 V.
Note: When the RTC remains active in Power Down mode, the oscillator which
generates the RTC clock signal will continue running.
If the supply voltage is reduced, the specified maximum CPU clock frequency for
this case must be taken into account.
The total power consumption in Power Down mode depends on the active circuitry
(whether the RTC is on or off) and on the current flowing through the port drivers. To
minimize the consumed current, the RTC and/or all pin drivers can be disabled (pins
switched to tristate) via a central control bitfield in register SYSCON2. If an application
requires one or more port drivers to remain active even in Power Down mode, individual
port drivers can be disabled simply by configuring them for input.
The bus interface pins can be separately disabled by releasing the external bus (disable
all address windows by clearing the BUSACT bits) and switching the ports to input (if
necessary). Of course, the required software in this case must be executed from internal
memory.
User’s Manual
21-8
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
21.3.1
Output Pins Status During Power Reduction Modes
In Idle mode, the CPU clocks are turned off and all peripherals continue their normal
operation. Therefore, all port pins configured as general purpose output pins, will output
the last data value written to their port output latches. If the alternate output function of
a port pin is used by a peripheral, the state of the pin is determined by the operation of
the peripheral.
Port pins used for bus control functions go into the state which represents the inactive
state of the respective function (e.g. WR), or to a defined state which is based on the last
bus access. Port pins used as external address/data bus hold the address/data which
was output during the last external memory access before entry into Idle mode under the
following conditions:
• P0H.2-0 outputs the high bits of the last address if a multiplexed bus mode with 8-bit
data bus is used. Otherwise, P0H.2-0 is floating. P0L is always floating in Idle mode.
• PORT1 outputs the lower 16 bits of the last address if a demultiplexed bus mode is
used. Otherwise, the output pins of PORT1 represent the port latch data.
In Sleep mode, the oscillator (except for RTC operation) and the clocks to the CPU and
to the peripherals are turned off. As in Idle mode, all port pins configured as general
purpose output pins will output the last data value written to their port output latches.
When the alternate output function of a port pin is used by a peripheral the state of this
pin is determined by the last action of the peripheral before the clocks were switched off.
In Power Down mode, the oscillator (except for RTC operation) and the clocks to the
CPU and to the peripherals are turned off. As in Idle mode, all port pins configured as
general purpose output pins will output the last data value written to their port output
latches.
When the alternate output function of a port pin is used by a peripheral, the state of this
pin is determined by the last action of the peripheral before the clocks were switched off.
Note: All pin drivers can be switched off by selecting the general port disable function
prior to entering Power Down mode.
When the supply voltage is lowered in Power Down mode, the high voltage of
output pins will decrease accordingly.
User’s Manual
21-9
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
Table 21-1
State of C164CM Output Pins in Idle and Power Down Modes
C164CM
External Bus Enabled
Output Pin(s) Idle Mode
Sleep and
Power Down
Idle Mode
CLKOUT
Active (toggling) High
Active (toggling) High
FOUT
Active (toggling) Hold (high / low) Active (toggling) Hold (high / low)
ALE
Low
Low
RD, WR
High
High
P0L
Floating
Port Latch Data
P0H
A10 … A81) / Float
Port Latch Data
PORT1
Last Address2) / Port Latch Data
Port Latch Data
RSTOUT
High if EINIT was executed before entering Idle or Power Down mode,
Low otherwise.
Other Port
Output Pins
Port Latch Data / Alternate Function
1)
For multiplexed buses with 8-bit data bus.
2)
For demultiplexed buses.
User’s Manual
21-10
No External Bus
Sleep and
Power Down
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
21.4
Slow Down Operation
A separate clock path can be selected for Slow Down operation, bypassing the basic
clock path used for standard operation. The programmable Slow Down Divider (SDD)
divides the oscillator frequency by a factor of 1 … 32 which is specified via bitfield
CLKREL in register SYSCON2 (factor = <CLKREL>+1). When bitfield CLKREL is written
during SDD operation, the reload counter will output one more clock pulse with the “old”
frequency in order to resynchronize internally before generating the “new” frequency.
If direct drive mode is configured, clock signal fDD is directly fed to fCPU. If prescaler
mode is configured, clock signal fDD is additionally divided by 2:1 to generate fCPU (see
examples below).
CLKREL
fOSC
Reload Counter
fSDD
fOSC
Factor = 3, Direct Drive
fSDD
Factor = 5, Direct Drive
Factor = 3, Prescaler
MCD04477
Figure 21-3 Slow Down Divider Operation
Using a 5 MHz input clock, for example, the on-chip logic may be run at a frequency
down to 156.25 kHz (or 78 kHz) without an external hardware change. An implemented
PLL may be switched off in this case or may continue running, depending on the
requirements of the application (see Table 21-2).
Note: During Slow Down operation, the entire device (including bus interface and
generation of signals CLKOUT or FOUT) is clocked with the SDD clock (see
Figure 21-3).
User’s Manual
21-11
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
Table 21-2
PLL Operation in Slow Down Mode
Advantage
Disadvantage
Oscillator
Watchdog
PLL
running
Fast switching back to
basic clock source
PLL adds to power
consumption
Active if not
disabled via bit
OWDDIS
PLL
off
PLL causes no
additional power
consumption
PLL must lock before
Disabled
switching back to the
basic clock source (if the
PLL is the basic clock
source)
These clock options are selected via bitfield CLKCON in register SYSCON2. A state
machine controls the switching mechanism itself and ensures a continuous and glitchfree clock signal to the on-chip logic. This is especially important when switching back to
PLL frequency after the PLL has temporarily been switched off. In this case, the clock
source can be switched back either automatically as soon as the PLL is locked again
(indicated by bit CLKLOCK in register SYSCON2), or manually, (under software control,
after bit CLKLOCK has become ‘1’). The latter way is preferable if the application
requires a defined point at which the frequency changes.
Note: When the PLL is the basic clock source and a reset occurs during SDD operation
with the PLL off, the internal reset condition is extended so the PLL can lock before
execution begins. The reset condition is terminated prematurely if no stable
oscillator clock is detected. This ensures the operability of the device in case of a
missing input clock signal.
Switching to Slow Down operation affects frequency sensitive peripherals such as serial
interfaces, timers, PWM, etc. If these units are to be operated in Slow Down mode, their
precalers or reload values must be adapted. Please note that the reduced CPU
frequency decreases such things as timer resolution and increases the step width for
example for baudrate generation. The oscillator frequency in such a case should be
chosen to accommodate the required resolutions and/or baudrates.
User’s Manual
21-12
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
SYSCON2
System Control Reg.2
15
14
13
CLK
LOCK
rh
12
11
CLKREL
rw
ESFR (F1D0H/E8H)
10
9
8
7
6
CLKCON SCS RCS
rw
rw
rw
Reset Value: 00X0H
5
4
3
2
1
PDCON
SYSRLS
rw
rwh
Bit
Function
SYSRLS
Register Release Function (Unlock field)
Must be written in a defined way in order to execute the unlock
sequence. See separate description (Table 21-6).
PDCON
Power Down Control (during power down mode)
00: RTC = On,
Ports = On (default after reset).
01: RTC = On,
Ports = Off.
10: RTC = Off,
Ports = On.
11: RTC = Off,
Ports = Off.
RCS
RTC Clock Source (not affected by a reset!)
0:
Main oscillator.
1:
Reserved.
SCS
SDD Clock Source (not affected by a reset!)
0:
Main oscillator.
1:
Reserved.
CLKCON
Clock State Control
00: Running on configured basic frequency.
01: Running on slow down frequency, PLL remains ON.
10: Running on slow down frequency, PLL switched OFF.
11: Reserved. Do not use this combination.
CLKREL
Reload Counter Value for Slowdown Divider
(SDD factor = CLKREL + 1)
CLKLOCK
Clock Signal Status Bit
0:
Main oscillator is unstable or PLL is unlocked.
1:
Main oscillator is stable and PLL is locked.
0
Note: SYSCON2 (except for bitfield SYSRLS) is write protected after the execution of
EINIT unless it is released via the unlock sequence (see Table 21-6).
User’s Manual
21-13
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
Reset
xx
State Transition when writing "xx" to CLKCON.
Automatic Transition after clock is stable,
i.e. CLKLOCK = '1'.
01
1
2
00
10
10
5
01
00
10
10
01
3
4
00
MCA04478
Figure 21-4 Clock Switching State Machine
Table 21-3
Clock Switching State Description
State
Number
PLL
Status
fCPU
1
Locked1)
Basic
00
Standard operation on basic clock frequency.
2
Locked1)
SDD
01
SDD operation with PLL On1). Fast (without
delay) or manual switch back (from 5) to
basic clock frequency.
3
Transient1)
SDD
(00)
Intermediate state leading to state 1.
4
Transient1)
SDD
(01)
Intermediate state leading to state 2.
5
Off
SDD
10
SDD operation with PLL Off.
Reduced power consumption.
1)
CLK Note
Source CON
The indicated PLL status applies only if the PLL is selected as the basic clock source. If the basic clock source
is direct drive or prescaler, the PLL will not lock. If the oscillator watchdog is disabled (OWDDIS = ‘1’) the PLL
will be off.
User’s Manual
21-14
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
21.5
Flexible Peripheral Management
The power consumed by the C164CM also depends on the amount of active logic.
Peripheral management enables the system designer to deactivate those on-chip
peripherals not required in a given system status (such as a certain interface mode or
standby). All modules remaining active will continue with their usual performance. If all
modules fed by the Peripheral Clock Driver (PCD) are disabled and the other functions
fed by the PCD are not required, this clock driver itself may also be disabled to save
additional power.
This flexibility is accomplished by distributing the CPU clock via several clock drivers,
each of which can be separately controlled, and can also be smaller.
CCD
Clock
Generation
Idle Mode
CPU
PCD
PCDDIS
Peripherals,
Ports, Intr. Ctrl.
ICD
RTC
Interface
Peripherals,
FOUT
MCA04479
Figure 21-5 CPU Clock Distribution
Note: The Real Time Clock (RTC) is fed by a separate clock driver, so it can be kept
running even in Power Down mode while all the other circuitry is disconnected
from the clock.
The registers of the generic peripherals can be accessed even while the respective
module is disabled, as long as PCD is running. The registers of peripherals connected
to ICD can be accessed even in this case, of course. The registers of X-peripherals
cannot be accessed while the respective module is disabled by any means.
While a peripheral is disabled, its output pins remain in the state they had at the time of
disabling.
This flexible peripheral management is controlled by software via register SYSCON3 in
which each control bit is associated with an on-chip peripheral module.
User’s Manual
21-15
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
SYSCON3
System Control Reg.3
15
14
PCD
DIS
-
rw
-
13
ESFR (F1D4H/EAH)
12
11
10
9
DIS
-
-
-
-
rw
-
-
-
-
CAN1
8
7
CC6 CC2
DIS DIS
rw
rw
Reset Value: 0000H
6
5
4
-
-
-
-
-
-
Bit
Function (associated peripheral module)
ADCDIS
Analog/Digital Converter
ASC0DIS
USART ASC0
SSCDIS
Synchronous Serial Channel SSC
GPTDIS
General Purpose Timer Blocks
CC2DIS
CAPCOM2 Unit
CC6DIS
CAPCOM6 Unit
CAN1DIS
On-chip CAN Module 11)
PCDDIS
Peripheral Clock Driver (also X-Peripherals)
1)
3
2
1
GPT SSC
DIS DIS
rw
rw
0
ASC
ADC
0
DIS
DIS
rw
rw
When bit CAN1DIS is cleared the CAN module is re-activated by an internal reset signal and must then be reconfigured in order to operate properly.
Note: The allocation of peripheral disable bits within register SYSCON3 is device
specific and may be different in derivatives other than the C164CM.
SYSCON3 is write protected after the execution of EINIT unless it is released via
the unlock sequence (see Table 21-6).
When disabling the peripheral clock driver (PCD), the following details should be taken
into account:
• The clock signal for all connected peripherals is stopped. Make sure that all
peripherals enter a safe state before disabling PCD.
• The output signal CLKOUT will remain HIGH (FOUT will keep on toggling).
• Interrupt requests will still be recognized even while PCD is disabled.
• No new output values are gated from the port output latches to the output port pins
and no new input values are latched from the input port pins.
• No register access is possible for generic peripherals
(register access is possible for individually disabled generic peripherals,
no register access is possible for disabled X-Peripherals).
User’s Manual
21-16
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
21.6
Programmable Frequency Output Signal
The system clock output (CLKOUT) can be replaced by the programmable frequency
output signal fOUT. This signal can be controlled via software (unlike CLKOUT), and so
can be adapted to the requirements of connected external circuitry. The programmability
extends power management to the system level as circuitry external to the C164CM can
be influenced. Peripherals, for instance, can run at a scalable frequency or can be
switched off temporarily.
This clock signal is generated via a reload counter, so the output frequency can be
selected in small steps. An optional toggle latch can provide a clock signal with a 50%
duty cycle.
FORV
FOEN
Ctrl.
MUX
fCPU
FOCNT
fOUT
FOTL
FOSS
MCA04480
Figure 21-6 Clock Output Signal Generation
Signal fOUT always provides complete output periods (see Signal Waveforms below):
• When fOUT is started (FOEN --> ‘1’) FOCNT is loaded from FORV
• When fOUT is stopped (FOEN --> ‘0’) FOCNT is stopped when
fOUT has reached or is ‘0’.
Signal fOUT is independent of the peripheral clock driver PCD. While CLKOUT will stop
if PCD is disabled, fOUT will continue to toggle. Thus, external circuitry may be controlled
independently from on-chip peripherals.
Note: Counter FOCNT is clocked with the CPU clock signal fCPU (see Figure 21-6) and,
therefore, will also be influenced by the SDD operation.
Register FOCON provides control over the output signal generation (frequency,
waveform, activation) as well as all status information (counter value, FOTL).
User’s Manual
21-17
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
FOCON
Frequ. Output Control Reg.
15
14
FO
EN
SS
rw
rw
13
12
11
FO
10
SFR (FFAAH/D5H)
9
8
Reset Value: 0000H
7
6
5
4
3
2
FORV
-
FO
TL
FOCNT
rw
-
rwh
rwh
1
0
Bit
Function
FOCNT
Frequency Output Counter
FOTL
Frequency Output Toggle Latch
Is toggled upon each underflow of FOCNT.
FORV
Frequency Output Reload Value
Is copied to FOCNT upon each underflow of FOCNT.
FOSS
Frequency Output Signal Select
0:
Output of the toggle latch: duty cycle = 50%.
1:
Output of the reload counter: duty cycle depends on FORV.
FOEN
Frequency Output Enable
0:
Frequency output generation stops when signal fOUT is/gets low.
1:
FOCNT is running, fOUT is gated to pin.
First reload after 0-1 transition.
Note: It is not recommended to write to any part of bitfield FOCNT, especially while the
counter is running. Writing to FOCNT prior to starting the counter is obsolete
because it will be immediately reloaded from FORV. Writing to FOCNT during
operation may produce unintended counter values.
User’s Manual
21-18
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
Signal fOUT in the C164CM is an alternate function of pin P20.8/CLKOUT/FOUT.
Direction
0
MUX
"1"
1
CLKEN
FOUT_active
PortLatch
0
fOUT
MUX
0
1
MUX
fCPU
FOUT
1
MCA04481
Figure 21-7 Connection to Port Logic (Functional Approach)
A priority ranking determines which function controls the shared pin:
Table 21-4
Priority Ranking for Shared Output Pin
Priority
Function
Control
1
CLKOUT
CLKEN = ‘1’, FOEN = ‘x’
2
FOUT
CLKEN = ‘0’, FOEN = ‘1’
3
General purpose IO
CLKEN = ‘0’, FOEN = ‘0’
Note: For the generation of fOUT pin FOUT must be switched to output, i.e. DP20.8 = ‘1’.
While fOUT is disabled, the pin is controlled by the port latch (see Figure 21-7).
The port latch P20.8 must be ‘0’ in order to maintain the fOUT inactive level on the
pin.
User’s Manual
21-19
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
fCPU
1)
fOUT
(FORV = 0)
2)
1)
fOUT
(FORV = 2)
2)
1)
fOUT
(FORV = 5)
2)
FOEN
'1'
1) FOSS = '1', Output of Counter
2) FOSS = '0', Output of Toggle Latch
FOEN
The counter starts here
'0'
The counter stops here
MCT04482
Figure 21-8 Signal Waveforms
Note: The output signal (for FOSS = ‘1’) is high for the duration of one fCPU cycle for all
reload values FORV > 0. The output signal corresponds to fCPU, for FORV = 0.
User’s Manual
21-20
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
Output Frequency Calculation
The output frequency can be calculated as fOUT = fCPU / ((FORV + 1) × 2(1 - FOSS)),
so fOUTmin = fCPU / 128 (FORV = 3FH, FOSS = ‘0’),
and fOUTmax = fCPU / 1 (FORV = 00H, FOSS = ‘1’).
Selectable Output Frequency Range for fOUT
Table 21-5
fCPU
fOUT in [kHz] for FORV = xx, FOSS = 1/0
FORV for
fOUT = 1 MHz
00H
01H
02H
3EH
3FH
FOSS = 0 FOSS = 1
4 MHz
4000
2000
2000
1000
1333.33
666.67
63.492
31.746
62.5
31.25
01H
03H
10 MHz
10000
5000
5000
2500
3333.33
1666.67
158.73
79.365
156.25
78.125
04H
09H
12 MHz
12000
6000
6000
3000
4000
2000
190.476
95.238
187.5
93.75
05H
0BH
16 MHz
16000
8000
8000
4000
5333.33
2666.67
253.968
126.984
250
125
07H
0FH
20 MHz
20000
10000
10000
5000
6666.67
3333.33
317.46
158.73
312.5
156.25
09H
13H
25 MHz
25000
12500
12500
6250
8333.33
4166.67
396.825
198.413
390.625
195.313
0BH
18H
(1.04167)
0CH
(0.96154)
33 MHz
33000
16500
16500
8250
11000
5500
523.810
261.905
515.625
257.816
0FH
20H
(1.03125)
10H
(0.97059)
User’s Manual
21-21
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
21.7
Security Mechanism
The power management control registers belong to a set of registers (see Table 21-7)
which control functions and modes critical to the C164CM’s operation. For this reason,
they are locked (except for bitfield SYSRLS in register SYSCON2) after the execution of
EINIT (like register SYSCON) to ensure that these vital system functions cannot be
changed inadvertently, by software errors. However, because these registers control
important functions (e.g. the power management) they need to be accessed during
operation to select the appropriate mode. The system control software gains this access
via a special unlock sequence which allows one single write access to one register of
this set when executed properly. This provides maximum security.
Note: All these registers may be read at any time without restrictions.
The unlock sequence is executed by writing defined values to bitfield SYSRLS using
defined instructions (see Table 21-6). The instructions of the unlock sequence (including
the intended write access) must be secured with an EXTR instruction (switch to ESFR
space and lock interrupts).
Note: The unlock sequence is aborted if the locked range (EXTR) does not cover the
complete sequence.
The unlock sequence provides no write access to register SYSCON.
Table 21-6
Unlock Sequence for Secured Registers
Step
SYSRLS
Instruction
–
0000B1)
–
Notes
Status before release sequence
2)
1
1001B
BFLDL, OR, ORB ,
XOR, XORB2)
Read-Modify-Write access
2
0011B
MOV, MOVB2), MOVBS2),
MOVBZ2)
Write access
3
0111B
BSET, BMOV2), BMOVN2),
BOR2), BXOR2)
Read-Modify-Write access,
bit instruction
4
–
–
Single (read-modify-)write access
to one of the secured registers
–
0000B3)
–
Status after release sequence
1)
SYSRLS must be set to 0000B before the first step, if any OR command is used.
2)
Usually byte accesses should not be used for Special Function Registers.
3)
SYSRLS is cleared by hardware if unlock sequence and write access were successful.
Otherwise, SYSRLS shows the last value written.
User’s Manual
21-22
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
The following registers are secured by the described unlock sequence:
Table 21-7
Special Registers Secured by the Unlock Sequence
Register Name
Description
SYSCON1
Controls sleep mode
SYSCON2
Controls clock generation (SDD) and the unlock sequence itself
SYSCON3
Controls the flexible peripheral management
RSTCON
Controls the configuration of the C164CM
(basic clock generation mode, CS lines, segment address width)
and the length of the reset sequence
Code Examples
The code examples below show how the unlock sequence is used to access register
SYSCON2 (marked *!* in the comment column) in an application in order to change the
basic clock generation mode.
Examples where the PLL keeps running:
;________________________;______________________________________
ENTER_SLOWDOWN:
;Currently running on basic clock frequ.
MOV
SYSCON2, ZEROS
;Clear bits 3-0 (no EXTR required here)
EXTR #4H
;Switch to ESFR space and lock sequence
BFLDL SYSCON2,#0FH,#09H ;Unlock sequence, step 1 (1001B)
MOV
SYSCON2,#0003H
;Unlock sequence, step 2 (0011B)
BSET SYSCON2.2
;Unlock sequence, step 3 (0111B)
;Single access to one locked register
BFLDH SYSCON2,#03H,#01H ;CLKCON=01B --> SDD frequency, PLL on *!*
;________________________;______________________________________
EXIT_SLOWDOWN:
;Currently running on SDD frequency
MOV
SYSCON2, ZEROS
;Clear bits 3-0 (no EXTR required here)
EXTR #4H
;Switch to ESFR space and lock sequence
BFLDL SYSCON2,#0FH,#09H ;Unlock sequence, step 1 (1001B)
MOV
SYSCON2,#0003H
;Unlock sequence, step 2 (0011B)
BSET SYSCON2.2
;Unlock sequence, step 3 (0111B)
;Single access to one locked register
BFLDH SYSCON2,#03H,#00H ;CLKCON=00B --> basic frequency
*!*
User’s Manual
21-23
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
Examples where the PLL is disabled:
;________________________;______________________________________
ENTER_SLOWDOWN:
;Currently running on basic clock frequ.
EXTR #1H
;Next access to ESFR space
BCLR ISNC.2
;PLLIE=’0’, i.e. PLL interrupt disabled
MOV
SYSCON2, ZEROS
;Clear bits 3-0 (no EXTR required here)
EXTR #4H
;Switch to ESFR space and lock sequence
BFLDL SYSCON2,#0FH,#09H ;Unlock sequence, step 1 (1001B)
MOV
SYSCON2,#0003H
;Unlock sequence, step 2 (0011B)
BSET SYSCON2.2
;Unlock sequence, step 3 (0111B)
;Single access to one locked register
BFLDH SYSCON2,#03H,#02H ;CLKCON=10B --> SDD frequency, PLL off*!*
;________________________;______________________________________
SDD_EXIT_AUTO:
;Currently running on SDD frequency
MOV
SYSCON2, ZEROS
;Clear bits 3-0 (no EXTR required here)
EXTR #4H
;Switch to ESFR space and lock sequence
BFLDL SYSCON2,#0FH,#09H ;Unlock sequence, step 1 (1001B)
MOV
SYSCON2,#0003H
;Unlock sequence, step 2 (0011B)
BSET SYSCON2.2
;Unlock sequence, step 3 (0111B)
;Single access to one locked register
BFLDH SYSCON2,#03H,#00H ;CLKCON=00B--> basic frequ./start PLL*!*
EXTR #1H
;Next access to ESFR space
BSET ISNC.2
;PLLIE=’1’, i.e. PLL interrupt enabled
User’s Manual
21-24
V1.0, 2002-02
C164CM/C164SM
Derivatives
Power Management
;________________________;______________________________________
SDD_EXIT_MANUAL:
;Currently running on SDD frequency
MOV
SYSCON2, ZEROS
;Clear bits 3-0 (no EXTR required here)
EXTR #4H
;Switch to ESFR space and lock sequence
BFLDL SYSCON2,#0FH,#09H ;Unlock sequence, step 1 (1001B)
MOV
SYSCON2,#0003H
;Unlock sequence, step 2 (0011B)
BSET SYSCON2.2
;Unlock sequence, step 3 (0111B)
;Single access to one locked register
BFLDH SYSCON2,#03H,#01H ;CLKCON=01B --> stay on SDD/start PLL *!*
;
USER_CODE:
;Space for any user code that...
;...must or can be executed before...
;...switching back to basic clock
CLOCK_OK:
EXTR #1H
;Next access to ESFR space
JNB
SYSCON2.15,CLOCK_OK;Wait until clock OK (CLKLOCK=’1’)
;
MOV
SYSCON2, ZEROS
;Clear bits 3-0 (no EXTR required here)
EXTR #4H
;Switch to ESFR space and lock sequence
BFLDL SYSCON2,#0FH,#09H ;Unlock sequence, step 1 (1001B)
MOV
SYSCON2,#0003H
;Unlock sequence, step 2 (0011B)
BSET SYSCON2.2
;Unlock sequence, step 3 (0111B)
;Single access to one locked register
BFLDH SYSCON2,#03H,#00H ;CLKCON=00B --> basic frequency
*!*
EXTR #1H
;Next access to ESFR space
BSET ISNC.2
;PLLIE=’1’, i.e. PLL interrupt enabled
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System Programming
22
System Programming
A number of features have been incorporated into the instruction set of the C164CM, to
facilitate software development, including constructs for modularity, loops, and context
switching. In many cases, commonly used instruction sequences have been simplified
while their flexibility has been enhanced. The following programming features help to
fully utilize this instruction set.
Instructions Provided as Subsets of Instructions
In many cases, instructions found in other microcontrollers are provided as subsets of
more powerful instructions in the C164CM. This allows the same functionality to be
provided while decreasing the hardware required and decreasing decode complexity. To
assist with assembly programming, these instructions which are familiar from other
microcontrollers, can be built in macros, thus providing the same names.
Direct Substitution Instructions are instructions known from other microcontrollers
which can be replaced by the following instructions of the C164CM:
Table 22-1
Substitution of Instructions
Substituted Instruction
C164CM Instruction
Function
CLR
Rn
AND
Rn, #0H
Clear register
CPLB
Bit
BMOVN
Bit, Bit
Complement bit
DEC
Rn
SUB
Rn, #1H
Decrement register
INC
Rn
ADD
Rn, #1H
Increment register
SWAPB
Rn
ROR
Rn, #8H
Swap bytes within word
Modification of System Flags is performed using bit set or bit clear instructions
(BSET, BCLR). All bit and word instructions can access the PSW register, so instructions
such as CLEAR CARRY or ENABLE INTERRUPTS are not required.
External Memory Data Access does not require special instructions to load data
pointers or explicitly load and store external data. The C164CM provides a Von
Neumann memory architecture and its on-chip hardware automatically detects accesses
to internal RAM, GPRs, and SFRs.
Multiplication and Division
Multiplication and division of words and double words are provided through multiple
cycle instructions implementing a Booth algorithm. Each instruction implicitly uses the
32-bit register MD (MDL = lower 16 bits, MDH = upper 16 bits). The MDRIU flag (Multiply
or Divide Register In Use) in register MDC is set whenever either half of this register is
written to or when a multiply/divide instruction is started. It is cleared whenever the MDL
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System Programming
register is read. Because an interrupt can be acknowledged before the contents of
register MD are saved, this flag is required to alert interrupt routines which require
multiply/divide hardware, so they can preserve register MD. This register, however, only
needs to be saved when an interrupt routine requires the use of the MD register and a
previous task has not saved the current result. This flag is easily tested by the Jump-onbit instructions.
Multiplication or division is simply performed by specifying the correct (signed or
unsigned) version of the multiply or divide instruction. The result is then stored in register
MD. The overflow flag (V) is set if the result from a multiply or divide instruction is greater
than 16 bits. This flag can be used to determine whether both word halves must be
transferred from register MD. The high portion of register MD (MDH) must be moved into
the register file or memory first to ensure that the MDRIU flag reflects the correct state.
The following instruction sequence performs an unsigned 16 by 16-bit multiplication:
SAVE:
JNB
SCXT
MDRIU, START;Test if MD was in use.
MDC, #0010H ;Save and clear control register,
;leaving MDRIU set
;(only required for interrupted
;multiply/divide instructions)
SAVED
;Indicate the save operation
MDH
;Save previous MD contents …
MDL
;… on system stack
BSET
PUSH
PUSH
START:
MULU
R1, R2
;Multiply 16·16 unsigned, Sets MDRIU
JMPR
cc_NV, COPYL;Test for only 16-bit result
MOV
R3, MDH
;Move high portion of MD
COPYL:
MOV
R4, MDL
;Move low portion of MD, Clears MDRIU
RESTORE:
JNB
SAVED, DONE ;Test if MD registers were saved
POP
MDL
;Restore registers
POP
MDH
POP
MDC
BCLR
SAVED
;Multiplication is completed,
;program continues
DONE:
…
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System Programming
The save sequence shown above and the restore sequence after COPYL are only
required if the current routine could have interrupted a previous routine which contained
a MUL or DIV instruction. Register MDC is also saved because it is possible that a
previous routine’s Multiply or Divide instruction was interrupted while in progress. In this
case, the information required to restart the instruction is contained in this register.
Register MDC must be cleared to be correctly initialized for a subsequent multiplication
or division. The old MDC contents must be popped from the stack before the RETI
instruction is executed.
For division, the user must first move the dividend into the MD register. If a 16/16-bit
division is specified, only the low portion of register MD must be loaded. The result is also
stored into register MD. The low portion (MDL) contains the integer result of the division,
while the high portion (MDH) contains the remainder.
The following instruction sequence performs a 32 by 16-bit division:
MOV
MOV
DIV
JMPR
MOV
MOV
MDH, R1
MDL, R2
R3
cc_V, ERROR
R3, MDH
R4, MDL
;Move dividend to MD register. Sets MDRIU
;Move low portion to MD
;Divide 32/16 signed, R3 holds divisor
;Test for divide overflow
;Move remainder to R3
;Move integer result to R4. Clears MDRIU
Whenever a multiply or divide instruction is interrupted while in progress, the address of
the interrupted instruction is pushed onto the stack and the MULIP flag in the PSW of the
interrupting routine is set. When the interrupt routine is exited with the RETI instruction,
this bit is implicitly tested before the old PSW is popped from the stack. If MULIP = ‘1’
the multiply/divide instruction is re-read from the location popped from the stack (return
address) and will be completed after the RETI instruction has been executed.
Note: The MULIP flag is part of the context of the interrupted task. When the
interrupting routine does not return to the interrupted task (for example, scheduler
switches to another task) the MULIP flag must be set or cleared according to the
context of the task to be executed next.
BCD Calculations
No direct support for BCD calculations is provided in the C164CM. BCD calculations are
performed by converting BCD data to binary data, performing the desired calculations
using standard data types, and converting the result back to BCD data. Due to the
enhanced performance of division instructions, binary data is quickly converted to BCD
data through division by 10D. Conversion from BCD data to binary data is enhanced by
multiple bit shift instructions. This provides similar performance compared to instructions
directly supporting BCD data types without requiring additional hardware.
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22.1
Stack Operations
The C164CM supports two types of stacks: the system stack and the user stack. The
system stack is used implicitly by the controller and is located in the internal RAM. The
user stack provides stack access to the user in either the internal or external memory.
Both stack types grow from high memory addresses to low memory addresses.
Internal System Stack
A system stack is provided to store return vectors, segment pointers, and processor
status for procedures and interrupt routines. A system Stack Pointer register, SP, points
to the top of the stack. This pointer is decremented when data is pushed onto the stack,
and incremented when data is popped.
The internal system stack can also be used to temporarily store data or pass it between
subroutines or tasks. Instructions are provided to push or pop registers on/from the
system stack. However, in most cases, the register banking scheme provides the best
performance for passing data between multiple tasks.
Note: The system stack allows the storage of words only. Bytes must either be
converted to words or the respective other byte must be disregarded.
Register SP can be loaded with even byte addresses only (The LSB of SP is
always ‘0’).
Detection of stack overflow/underflow is supported by two registers, STKOV (Stack
Overflow Pointer) and STKUN (Stack Underflow Pointer). Specific system traps (Stack
Overflow trap, Stack Underflow trap) will be entered whenever the SP reaches either
boundary specified in these registers.
The contents of the stack pointer are compared to the contents of the overflow register,
whenever the SP is DECREMENTED either by a CALL, PUSH, or SUB instruction. An
overflow trap will be entered when the SP value is less than the value in the stack
overflow register.
The contents of the stack pointer are compared to the contents of the underflow register,
whenever the SP is INCREMENTED either by a RET, POP, or ADD instruction. An
underflow trap will be entered when the SP value is greater than the value in the stack
underflow register.
Note: When a value is MOVED into the stack pointer, NO check against the overflow/
underflow registers is performed.
In many cases, the user will place a software reset instruction (SRST) into the stack
underflow and overflow trap service routines. This is an easy approach which does not
require special programming. However, this approach assumes that the defined internal
stack is sufficient for the current software and that exceeding its upper or lower boundary
represents a fatal error.
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It is also possible to use the stack underflow and stack overflow traps to cache portions
of a larger external stack. Only the portion of the system stack currently being used is
placed into the internal memory, thus allowing a greater portion of the internal RAM to
be used for program, data, or register banking. This approach assumes no error but
requires a set of control routines (see below).
Circular (Virtual) Stack
This basic technique allows pushing until the overflow boundary of the internal stack is
reached. At this point, a portion of the stacked data must be saved into external memory
to create space for further stack pushes. This is called “stack flushing”. When executing
a number of return or pop instructions, the upper boundary is reached (since the stack
empties upward to higher memory locations). Entries that have been previously saved
in external memory must now be restored. This is called “stack filling”. Because
procedure call instructions do not continue to nest infinitely, and call and return
instructions alternate, flushing and filling normally occur very infrequently. If this is not
true for a specific program environment, this technique should not be used because of
the overhead of flushing and filling.
The basic mechanism is the transformation via hardware of the addresses of a virtual
stack area, controlled via registers SP, STKOV and STKUN, to a defined physical stack
area within the internal RAM. This virtual stack area covers all possible locations to
which SP can point, i.e. 00’F000H through 00’FFFEH. Registers STKOV and STKUN
accept the same 4 KByte address range.
The size of the physical stack area within the internal RAM that is effectively used for
standard stack operations is defined via bitfield STKSZ in register SYSCON (see below).
Table 22-2
Circular Stack Address Transformation
STKSZ Stack Size Internal RAM Addresses (Words)
(Words)
of Physical Stack
Significant Bits
of Stack Ptr. SP
0 0 0B
256
00’FBFEH … 00’FA00H (Default after Reset)
SP.8 … SP.0
0 0 1B
128
00’FBFEH … 00’FB00H
SP.7 … SP.0
0 1 0B
64
00’FBFEH … 00’FB80H
SP.6 … SP.0
0 1 1B
32
00’FBFEH … 00’FBC0H
SP.5 … SP.0
1 0 0B
512
00’FBFEH … 00’F800H (not for 1 KByte IRAM) SP.9 … SP.0
1 0 1B
–
Reserved. Do not use this combination.
–
1 1 0B
–
Reserved. Do not use this combination.
–
1 1 1B
512 /
1024 /
1536
00’FDFEH … 00’FX00H (Note: No circular stack) SP.11 … SP.0
00’FX00H represents the lower IRAM limit, i.e.
1 KB: 00’FA00H, 2 KB: 00’F600H,
3 KB: 00’F200H
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The virtual stack addresses are transformed to physical stack addresses by
concatenating the significant bits of the Stack Pointer register SP (see Table 22-2) with
the complementary most significant bits of the upper limit of the physical stack area
(00’FBFEH). This transformation is done via hardware (see Figure 22-1).
The reset values (STKOV = FA00H, STKUN = FC00H, SP = FC00H, STKSZ = 000B)
map the virtual stack area directly to the physical stack area and allow use of the internal
system stack without any changes, provided that the 256 word area is not exceeded.
FBFE
FB80
FB80
H
H
H
1111 1011 1111 1110
FBFE
1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 0 Phys.A.
FA00
1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 0 <SP>
F800
H
H
H
After PUSH
FBFE
FBFE
FB7E
H
H
H
1111 1011 1111 1110
1111 1010 0000 0000
1111 1000 0000 0000
After PUSH
1111 1011 1111 1110
FBFE
1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 0 Phys.A.
FBFE
1 1 1 1 1 0 1 1 0 1 1 1 1 1 1 0 <SP>
F7FE
64 words
Stack Size
H
H
H
1111 1011 1111 1110
1111 1011 1111 1110
1111 0111 1111 1110
256 words
MCA04408
Figure 22-1 Physical Stack Address Generation
The following example demonstrates the circular stack mechanism which is also an
effect of this virtual stack mapping: First, register R1 is pushed onto the lowest physical
stack location according to the selected maximum stack size. With the following
instruction, register R2 will be pushed onto the highest physical stack location although
the SP is decremented by 2, as for the previous push operation.
MOV
…
PUSH
PUSH
SP, #0F802H ;Set SP before last entry …
;… of physical stack of 256 words
;(SP)= F802H: Physical stack addr.= FA02H
R1
;(SP)= F800H: Physical stack addr.= FA00H
R2
;(SP)= F7FEH: Physical stack addr.= FBFEH
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The effect of the address transformation is that the physical stack addresses wrap
around from the end of the defined area to its beginning. When flushing and filling the
internal stack, this circular stack mechanism requires moving only that portion of stack
data which is really to be re-used (the upper part of the defined stack area) instead of the
entire stack area. Stack data that remain in the lower part of the internal stack need not
be moved by the distance of the space being flushed or filled, as the Stack Pointer
automatically wraps around to the beginning of the freed part of the stack area.
Note: This circular stack technique is applicable for stack sizes of 32 to 512 words
(STKSZ = ‘000B’ to ‘100B’), it does not work with option STKSZ = ‘111B’, which
uses the complete internal RAM for system stack.
In the latter case, the address transformation mechanism is deactivated.
When a boundary is reached, the stack underflow or overflow trap is entered in which
the user moves a predetermined portion of the internal stack to or from the external
stack. The amount of data transferred is determined by the average stack space required
by routines and the frequency of calls, traps, interrupts, and returns. In most cases, this
will be approximately one-quarter to one-tenth the size of the internal stack. After the
transfer is complete, the boundary pointers are updated to reflect the newly allocated
space on the internal stack. Thus, the user is free to write code without concern for the
internal stack limits. Only the execution time required by the trap routines affects user
programs.
The following procedure initializes the controller for use of the circular stack mechanism:
• Specify the size of the physical system stack area within the internal RAM (bitfield
STKSZ in register SYSCON).
• Define two pointers which specify the upper and lower boundary of the external stack.
These values are then tested in the stack underflow and overflow trap routines when
moving data.
• Set the stack overflow pointer (STKOV) to the limit of the defined internal stack area
plus six words (for the reserved space to store two interrupt entries).
The internal stack will now fill until the overflow pointer is reached. After entry into the
overflow trap procedure, the top of the stack will be copied to the external memory. The
internal pointers will then be modified to reflect the newly allocated space. After exiting
from the trap procedure, the internal stack will wrap around to the top of the internal stack
and continue to grow until the new value of the stack overflow pointer is reached.
When the underflow pointer is reached while the stack is emptied, the bottom of stack is
reloaded from the external memory and the internal pointers are adjusted accordingly.
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Linear Stack
The C164CM also offers a linear stack option (STKSZ = ‘111B’), in which the system
stack may use the entire internal RAM area. This provides a large system stack without
requiring procedures to handle data transfers for a circular stack. However, this method
also leaves less RAM space for variables or code. The RAM area that may be effectively
consumed by the system stack is defined via the STKUN and STKOV pointers. The
underflow and overflow traps in this case serve for fatal error detection only.
For the linear stack option, all modifiable bits of register SP are used to access the
physical stack. Although the stack pointer may cover addresses from 00’F000H up to
00’FFFEH the (physical) system stack must be located within the internal RAM and,
therefore, may use only the address range 00’F200H/00’F600H/00’FA00H to 00’FDFEH.
It is the user’s responsibility to restrict the system stack to the range of the internal RAM.
Note: Avoid stack accesses below the IRAM area (ESFR space and reserved area) and
within address range 00’FE00H and 00’FFFEH (SFR space).
Otherwise unpredictable results will occur.
User Stacks
User stacks provide the ability to create task-specific data stacks and to off-load data
from the system stack. The user may push both bytes and words onto a user stack, but
is responsible for using the appropriate instructions when popping data from the specific
user stack. No hardware detection of overflow or underflow of a user stack is provided.
The following addressing modes allow implementation of user stacks:
[–Rw], Rb or [–Rw], Rw: Pre-decrement Indirect Addressing.
Used to push one byte or word onto a user stack. This mode is only available for MOV
instructions and can specify any GPR as the user stack pointer.
Rb, [Rwi+] or Rw, [Rwi+]: Post-increment Index Register Indirect Addressing.
Used to pop one byte or word from a user stack. This mode is available to most
instructions, but only GPRs R0-R3 can be specified as the user stack pointer.
Rb, [Rw+] or Rw, [Rw+]: Post-increment Indirect Addressing.
Used to pop one byte or word from a user stack. This mode is only available for MOV
instructions and can specify any GPR as the user stack pointer.
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22.2
Register Banking
Register banking provides the user with an extremely fast method for switching user
context. A single machine cycle instruction saves the old bank and enters a new register
bank. Each register bank may assign up to 16 registers. Each register bank should be
allocated during coding based on the needs of each task. After the internal memory has
been partitioned into a register bank space, internal stack space, and a global internal
memory area, each bank pointer is then assigned. Thus, upon entry into a new task, the
appropriate bank pointer is used as the operand for the SCXT (switch context)
instruction. Upon exit from a task, a simple POP instruction to the Context Pointer (CP)
restores the previous task’s register bank.
22.3
Procedure Call Entry and Exit
To support modular programming, a procedure mechanism is provided to allow coding
of frequently used portions of code into subroutines. The CALL and RET instructions
store and restore the value of the Instruction Pointer (IP) on the system stack before and
after a subroutine is executed.
Procedures may be called conditionally with instructions CALLA or CALLI, or may be
called unconditionally using instructions CALLR or CALLS.
Note: Any data pushed onto the system stack during execution of the subroutine must
be popped before the RET instruction is executed.
Passing Parameters on the System Stack
PUSH instructions may be used to pass parameters via the system stack before the
subroutine is called; POP instructions may be used during execution of the subroutine.
Base plus offset indirect addressing also permits access to parameters without popping
these parameters from the stack during execution of the subroutine. Indirect addressing
provides a mechanism for accessing data referenced by data pointers, which are passed
to the subroutine.
Additionally, two instructions have been implemented to allow one parameter to be
passed on the system stack without additional software overhead.
The PCALL (push and call) instruction first pushes the ‘reg’ operand and the IP contents
onto the system stack and then passes control to the subroutine specified by the ‘caddr’
operand.
When exiting from the subroutine, the RETP (return and pop) instruction first pops the IP
and then the ‘reg’ operand from the system stack and returns to the calling program.
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Cross Segment Subroutine Calls
Calls to subroutines in different segments require the use of the CALLS (call intersegment subroutine) instruction. This instruction preserves both the CSP (Code
Segment Pointer) and the IP on the system stack.
Upon return from the subroutine, a RETS (return from inter-segment subroutine)
instruction must be used to restore both the CSP and IP. This ensures that the next
instruction after the CALLS instruction is fetched from the correct segment.
Note: It is possible to use CALLS within the same segment, but two words of the stack
are still used to store both the IP and CSP.
Providing Local Registers for Subroutines
The following methods are provided for subroutines which require local storage:
• Alternate Banks of Registers
• Saving and Restoring Registers
• Use of the System Stack for Local Registers
Alternate Bank of Registers: Upon entry into a subroutine, it is possible to specify a
new set of local registers by executing the SCXT (switch context) instruction. This
mechanism does not provide a method to recursively call a subroutine.
Saving and Restoring Registers: To provide local registers, the contents of the
registers which are required for use by the subroutine can be pushed onto the stack and
the previous values can be popped before returning to the calling routine. This is the
most common technique used today and it does provide a mechanism to support
recursive procedures. This method, however, requires two machine cycles per register
stored on the system stack (one cycle to PUSH the register, and one cycle to POP the
register).
Use of the System Stack for Local Registers: It is possible to use the SP and CP to
set up local subroutine register frames. This enables subroutines to dynamically allocate
local variables as needed within two machine cycles. A local frame is allocated by simply
subtracting the number of required local registers from the SP, and then moving the
value of the new SP to the CP.
This operation is supported through the SCXT (switch context) instruction with the
addressing mode ‘reg, mem’. Using this instruction saves the old contents of the CP on
the system stack and moves the value of the SP into CP (see the example below). Each
local register is then accessed as if it were a normal register. Upon exit from the
subroutine, first the old CP must be restored by popping it from the stack and then the
number of used local registers must be added to the SP to restore the allocated local
space back to the system stack.
Note: The system stack grows downward, while the register bank grows upward.
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System Programming
Old
Stack
Area
Old SP
R4
R3
R2
R1
New CP
Newly
Allocated
Register
Bank
R0
New SP
Old CPContents
New
Stack
Area
MCA04409
Figure 22-2 Local Registers
The software to provide the local register bank for the example shown in Figure 22-2 is
very compact:
After entering the subroutine:
SUB
SCXT
SP, #10D
CP, SP
;Free 5 words in the current system stack
;Set the new register bank pointer
Before exiting the subroutine:
POP
ADD
CP
SP, #10D
User’s Manual
;Restore the old register bank
;Release the 5 words …
;… of the current system stack
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22.4
Table Searching
A number of features have been included to decrease the execution time required to
search tables. First, branch delays are eliminated by the branch target cache after the
first iteration of the loop. Second, in non-sequentially searched tables, the enhanced
performance of the ALU allows more complicated hash algorithms to be processed to
obtain better table distribution. For sequentially searched tables, the auto-increment
indirect addressing mode and the E (end of table) flag stored in the PSW decrease the
number of overhead instructions executed in the loop.
The two examples below illustrate searching ordered tables and non-ordered tables,
respectively:
MOV
LOOP:
CMP
JMPR
R0, #BASE
;Move table base into R0
R1, [R0+]
;Compare target to table entry
cc_SGT, LOOP;Test whether target has not been found
Note: The last entry in the table must be greater than the largest possible target.
MOV
LOOP:
CMP
JMPR
R0, #BASE
;Move table base into R0
R1, [R0+]
;Compare target to table entry
cc_NET, LOOP;Test whether target is not found AND …
;… the end of table has not been reached.
Note: The last entry in the table must be equal to the lowest signed integer (8000H).
22.5
Floating Point Support
All floating point operations are performed using software. Standard multiple precision
instructions are used to perform calculations on data types that exceed the size of the
ALU. Multiple bit rotate and logic instructions allow easy masking and extracting of
portions of floating point numbers.
To decrease the time required to perform floating point operations, two hardware
features have been implemented in the CPU core. First, the PRIOR instruction aids in
normalizing floating point numbers by indicating the position of the first set bit in a GPR.
This result can then be used to rotate the floating point result accordingly. The second
feature assists in properly rounding the result of normalized floating point numbers
through the overflow (V) flag in the PSW. This flag is set when a one is shifted out of the
carry bit during shift right operations. The overflow flag and the carry flag are then used
to round the floating point result based on the desired rounding algorithm.
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22.6
Peripheral Control and Interface
All communication between peripherals and the CPU is performed by either PEC
transfers to and from internal memory or by explicit addressing of the SFRs associated
with the specific peripherals. After resetting the C164CM all peripherals (except the
watchdog timer) are disabled and initialized to default values. A desired configuration of
a specific peripheral is programmed using MOV instructions of either constants or
memory values to specific SFRs. Specific control flags may also be altered via bit
instructions.
Once in operation, the peripheral operates autonomously until an end condition is
reached; at which time, it requests a PEC transfer or requests CPU servicing through an
interrupt routine. Information may also be polled from peripherals through read accesses
to SFRs or bit operations including branch tests on specific control bits in SFRs. To
ensure proper allocation of peripherals among multiple tasks, a portion of the internal
memory has been made bit-addressable to allow user semaphores. Instructions have
also been provided to lock out tasks via software by setting or clearing user-specific bits
and conditionally branching based on these specific bits.
It is recommended that bit fields in control SFRs be updated using the BFLDH and
BFLDL instructions or a MOV instruction to avoid undesired intermediate modes of
operation which can occur if BCLR/BSET or AND/OR instruction sequences are used.
22.7
Trap/Interrupt Entry and Exit
Interrupt routines are entered when a requesting interrupt has a priority higher than the
current CPU priority level. Traps are entered regardless of the current CPU priority.
When either a trap or interrupt routine is entered, the state of the machine is preserved
on the system stack and a branch to the appropriate trap/interrupt vector is made.
All trap and interrupt routines require the use of the RETI (return from interrupt)
instruction to exit from the called routine. This instruction restores the system state from
the system stack and then branches back to the location at which the trap or interrupt
occurred.
User’s Manual
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V1.0, 2002-02
C164CM/C164SM
Derivatives
System Programming
22.8
Inseparable Instruction Sequences
The instructions of the C164CM are very efficient (most instructions execute in one
machine cycle). Even the multiplication and division are interruptible in order to minimize
the response latency to interrupt requests (internal and external). This is vital in many
microcontroller applications.
Some special occasions, however, require certain code sequences (such as semaphore
handling) to be executed uninterruptedly to function properly. This can be accomplished
by inhibiting interrupts during the respective code sequence by disabling and enabling
them before and after the sequence. The necessary overhead may be reduced by
means of the ATOMIC instruction which allows locking 1 … 4 instructions to an
inseparable code sequence, during which the interrupt system (standard interrupts and
PEC requests) and Class A Traps (NMI, stack overflow/underflow) are disabled. Class
B Traps (illegal opcode, illegal bus access, etc.), however, will interrupt the atomic
sequence, since it indicates a severe hardware problem.
The interrupt inhibit caused by an ATOMIC instruction gets active immediately; no other
instruction will enter the pipeline except the one following the ATOMIC instruction, and
no interrupt request will be serviced in between. All instructions requiring multiple cycles
or hold states are regarded as one instruction in this case (for example, MUL is one
instruction). Any instruction type can be used within an inseparable code sequence.
ATOMIC
MOV
MOV
MUL
MOV
#3
R0,
R1,
R0,
R2,
#1234H
#5678H
R1
MDL
;The next 3 instr. are locked (No NOP requ.)
;Instr. 1 (no other instr. enters pipeline!)
;Instr. 2
;Instr. 3: MUL regarded as one instruction
;This instruction is out of the scope …
;… of the ATOMIC instruction sequence
Note: As long as any Class B trap is pending (any of the class B trap flags in register
TFR is set) the ATOMIC instruction will not work. Clear the respective B trap flag
at the beginning of a B trap routine if ATOMIC shall be used within the routine.
22.9
Overriding the DPP Addressing Mechanism
The standard mechanism for accessing data locations uses one of the four data page
pointers (DPPx), which selects a 16-KByte data page, and a 14-bit offset within this data
page. The four DPPs allow immediate access to up to 64 KBytes of data. In applications
with large data arrays, especially in HLL applications using large memory models, this
may require frequent reloading of the DPPs, even for single accesses.
User’s Manual
22-14
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Programming
The EXTP (extend page) instruction allows switching to an arbitrary data page for
1 … 4 instructions without changing the current DPPs.
EXTP
MOV
MOV
R15, #1
R0, [R14]
R1, [R13]
;The override page number is stored in R15
;The (14-bit) page offset is stored in R14
;This instruction uses the std. DPP scheme!
The EXTS (extend segment) instruction allows switching to a 64 KByte segment
oriented data access scheme for 1 … 4 instructions without changing the current DPPs.
In this case all 16 bits of the operand address are used as segment offset, with the
segment taken from the EXTS instruction. This greatly simplifies address calculation with
continuous data, such as huge arrays in “C”.
EXTS
MOV
MOV
#15, #1
R0, [R14]
R1, [R13]
;The override seg. is 15 (0F’0000H..0F’FFFFH)
;The (16-bit) segment offset is stored in R14
;This instruction uses the std. DPP scheme!
Note: Instructions EXTP and EXTS inhibit interrupts the same way as ATOMIC.
As long as any Class B trap is pending (any of the class B trap flags in register
TFR is set) the EXTend instructions will not work. Clear the respective B trap flag
at the beginning of a B trap routine if EXT* shall be used within the routine.
Short Addressing in Extended SFR (ESFR) Space
The short addressing modes of the C164CM (REG or BITOFF) implicitly access the SFR
space. The additional ESFR space would need to be accessed via long addressing
modes (MEM or [Rw]). The EXTR (extend register) instruction redirects accesses in
short addressing modes to the ESFR space for 1 … 4 instructions, so the additional
registers can be accessed this way, too.
The EXTPR and EXTSR instructions combine the DPP override mechanism with the
redirection to the ESFR space using a single instruction.
Note: Instructions EXTR, EXTPR, and EXTSR inhibit interrupts the same way as ATOMIC
instructions. Switching to the ESFR area and data page overriding are checked by
the development tools or are handled automatically.
Nested Locked Sequences
Each described extension instruction and the ATOMIC instruction start an internal
“extension counter” counting the effected instructions. When another extension or
ATOMIC instruction is contained in the current locked sequence, this counter is restarted
with the value of the new instruction. This allows construction of locked sequences
longer than 4 instructions.
Note: Interrupt latencies may be increased when using locked code sequences.
PEC requests are not serviced during idle mode, if the IDLE instruction is part of
a locked sequence.
User’s Manual
22-15
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Programming
22.10
Handling the Internal Code Memory
The Mask-ROM/OTP/Flash versions of the C164CM provide on-chip code memory that
may store code as well as data. The lower 32 KBytes of this code memory are referred
to as the “internal ROM area”. Access to this internal ROM area is controlled during the
reset configuration and via software. The ROM area may be mapped to segment 0, to
segment 1, or the code memory may be disabled.
Note: The internal ROM area always occupies an address area of 32 KBytes, even if the
implemented mask ROM/OTP/Flash memory is smaller than that (such as
8 KBytes).
Of course, the total implemented memory may exceed 32 KBytes.
Code Memory Configuration During Reset
The control input pin EA (External Access) enables the user to define the address area
from which the first instructions after reset are fetched. When EA is low (‘0’) during reset,
the internal code memory is disabled and the first instructions are fetched from external
memory. When EA is high (‘1’) during reset, the internal code memory is globally enabled
and the first instructions are fetched from the internal memory.
Note: Be sure not to select internal memory access after reset on ROMless devices.
Mapping the Internal ROM Area
After reset, the internal ROM area is mapped into segment 0, the “system segment”
(00’0000H … 00’7FFFH) as a default. This is necessary to allow the first instructions to
be fetched from locations 00’0000H ff. The ROM area may be mapped to segment 1
(01’0000H … 01’7FFFH) by setting bit ROMS1 in register SYSCON. The internal ROM
area may now be accessed through the lower half of segment 1, while accesses to
segment 0 will now be made to external memory. This adds flexibility to the system
software. The interrupt/trap vector table, which uses locations 00’0000H through
00’01FFH, is now part of the external memory and may therefore be modified; that is to
say, the system software may now change interrupt/trap handlers according to the
current condition of the system. The internal code memory can still be used for fixed
software routines such as IO drivers, math libraries, application specific invariant
routines, tables, etc. This combines the advantage of an integrated non-volatile memory
with the advantage of a flexible, adaptable software system.
User’s Manual
22-16
V1.0, 2002-02
C164CM/C164SM
Derivatives
System Programming
Enabling and Disabling Internal Code Memory After Reset
If the internal code memory does not contain an appropriate startup code, the system
may be booted from external memory, while the internal memory is enabled afterwards
to provide access to library routines, tables, etc.
If the internal code memory contains only the startup code and/or test software, the
system may be booted from internal memory, which may then be disabled, after the
software has switched to executing from external memory (for example). This may be
done to free the address space occupied by the internal code memory which would no
longer be necessary.
User’s Manual
22-17
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C164CM/C164SM
Derivatives
System Programming
22.11
Pits, Traps, and Mines
Although handling the internal code memory provides a powerful means of enhancing
the overall performance and flexibility of a system, extreme care must be taken to avoid
a system crash. Instruction memory is the most crucial resource for the C164CM and it
must be ensured that it never runs out. The following precautions help to take advantage
of the methods mentioned above without jeopardizing system security.
Internal code memory access after reset: When the first instructions are to be fetched
from internal memory (EA = ‘1’), the device must contain code memory containing a valid
reset vector and valid code at its destination.
Mapping the internal ROM area to segment 1: Due to instruction pipelining, any new
ROM mapping will at the earliest become valid for the second instruction after the
instruction which has changed the ROM mapping. To enable accesses to the ROM area
after mapping a branch to the newly selected ROM area (JMPS) and reloading of all data
page pointers is required.
This also applies to re-mapping the internal ROM area to segment 0.
Enabling the internal code memory after reset: When enabling the internal code
memory after having booted the system from external memory, note that the C164CM
will then access the internal memory using the current segment offset, rather than
accessing external memory.
Disabling the internal code memory after reset: When disabling the internal code
memory after having booted the system from there, note that the C164CM will not
access external memory before a jump to segment 0 (in this case) is executed.
General Rules
When mapping the code memory no instruction or data accesses should be made to the
internal memory, otherwise unpredictable results may occur.
To avoid these problems, the instructions which configure the internal code memory
should be executed from external memory or from the on-chip RAM.
Whenever the internal code memory is disabled, enabled, or remapped, the DPPs must
be explicitly (re)loaded to enable correct data accesses to the internal and/or external
memory.
User’s Manual
22-18
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
23
Register Set
This chapter summarizes all registers implemented in the C164CM and explains the
description format used in the chapters which describe the functions and layout of the
Special Function Registers (SFRs).
For easy reference, the registers are ordered according to two different keys (except for
GPRs):
• Ordered by address, to identify which register a given address references,
• Ordered by register name, to find the location of a specific register.
23.1
Register Description Format
In their respective chapters, the functions and the layout of the SFRs are described in a
specific format which provides various details about each special function register. The
example below shows how to interpret these details.
REG_NAME
Name of Register
15
14
13
E/SFR (A16H/A8H)
12
11
10
9
8
<empty for byte registers>
-
-
Bit
-
-
-
-
7
std
-
-
rw
6
Reset Value: ****H
5
4
3
read/
write
hw write read
bit
bit
bit
rwh rw
r
w
2
1
0
bitfield
rw
Function
bit(field)name Explanation of bit(field)name
Description of the functions controlled by the different possible values
of this bit(field).
Elements:
REG_NAME
A16/A8
SFR/ESFR/XReg
(**) **
r/w
*h
User’s Manual
Short name of this register
Long 16-bit address / Short 8-bit address
Register space (SFR, ESFR or External/XBUS Register)
Register contents after reset
0/1: defined value, ‘X’: undefined,
‘U’: unchanged (undefined (‘X’) after power up)
Access modes: can be read and/or write
Bits that are set/cleared by hardware are marked with
a shaded access box and an ‘h’ in it.
23-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
23.2
CPU General Purpose Registers (GPRs)
The General Purpose Registers (GPRs) form the register bank with which the CPU
works. This register bank may be located anywhere within the internal RAM via the
Context Pointer (CP). Due to the addressing mechanism, GPR banks can reside only
within the internal RAM. All GPRs are bit-addressable.
Table 23-1
General Purpose Word Registers
Name
Physical
Address
8-bit
Address
Description
R0
(CP) + 0
F0H
CPU General Purpose (Word) Reg. R0
UUUUH
R1
(CP) + 2
F1H
CPU General Purpose (Word) Reg. R1
UUUUH
R2
(CP) + 4
F2H
CPU General Purpose (Word) Reg. R2
UUUUH
R3
(CP) + 6
F3H
CPU General Purpose (Word) Reg. R3
UUUUH
R4
(CP) + 8
F4H
CPU General Purpose (Word) Reg. R4
UUUUH
R5
(CP) + 10
F5H
CPU General Purpose (Word) Reg. R5
UUUUH
R6
(CP) + 12
F6H
CPU General Purpose (Word) Reg. R6
UUUUH
R7
(CP) + 14
F7H
CPU General Purpose (Word) Reg. R7
UUUUH
R8
(CP) + 16
F8H
CPU General Purpose (Word) Reg. R8
UUUUH
R9
(CP) + 18
F9H
CPU General Purpose (Word) Reg. R9
UUUUH
R10
(CP) + 20
FAH
CPU General Purpose (Word) Reg. R10
UUUUH
R11
(CP) + 22
FBH
CPU General Purpose (Word) Reg. R11
UUUUH
R12
(CP) + 24
FCH
CPU General Purpose (Word) Reg. R12
UUUUH
R13
(CP) + 26
FDH
CPU General Purpose (Word) Reg. R13
UUUUH
R14
(CP) + 28
FEH
CPU General Purpose (Word) Reg. R14
UUUUH
R15
(CP) + 30
FFH
CPU General Purpose (Word) Reg. R15
UUUUH
User’s Manual
23-2
Reset
Value
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
The first 8 GPRs (R7 … R0) may also be accessed bytewise. Other than with SFRs,
writing to a GPR byte does not affect the other byte of the respective GPR.
The respective halves of the byte-accessible registers receive special names:
Table 23-2
General Purpose Byte Registers
Name
Physical 8-bit
Address Address
Description
RL0
(CP) + 0
F0H
CPU General Purpose (Byte) Reg. RL0
UUH
RH0
(CP) + 1
F1H
CPU General Purpose (Byte) Reg. RH0
UUH
RL1
(CP) + 2
F2H
CPU General Purpose (Byte) Reg. RL1
UUH
RH1
(CP) + 3
F3H
CPU General Purpose (Byte) Reg. RH1
UUH
RL2
(CP) + 4
F4H
CPU General Purpose (Byte) Reg. RL2
UUH
RH2
(CP) + 5
F5H
CPU General Purpose (Byte) Reg. RH2
UUH
RL3
(CP) + 6
F6H
CPU General Purpose (Byte) Reg. RL3
UUH
RH3
(CP) + 7
F7H
CPU General Purpose (Byte) Reg. RH3
UUH
RL4
(CP) + 8
F8H
CPU General Purpose (Byte) Reg. RL4
UUH
RH4
(CP) + 9
F9H
CPU General Purpose (Byte) Reg. RH4
UUH
RL5
(CP) + 10 FAH
CPU General Purpose (Byte) Reg. RL5
UUH
RH5
(CP) + 11 FBH
CPU General Purpose (Byte) Reg. RH5
UUH
RL6
(CP) + 12 FCH
CPU General Purpose (Byte) Reg. RL6
UUH
RH6
(CP) + 13 FDH
CPU General Purpose (Byte) Reg. RH6
UUH
RL7
(CP) + 14 FEH
CPU General Purpose (Byte) Reg. RL7
UUH
RH7
(CP) + 15 FFH
CPU General Purpose (Byte) Reg. RH7
UUH
User’s Manual
23-3
Reset
Value
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
23.3
Registers Ordered by Name
Table 23-3 lists all registers implemented in the C164CM in alphabetical order. The
following markings assist in classifying the listed registers:
“b” in the “Name” column marks Bit-addressable SFRs.
“E” in the “Physical Address” column marks (E)SFRs in the Extended SFR-Space.
“m” in the “Physical Address” column marks SFRs without short 8-bit address.
“X” in the “Physical Address” column marks registers within on-chip X-Peripherals.
Table 23-3
C164CM Registers, Ordered by Name
Name
Physical
Address
8-Bit Description
Addr.
Reset
Value
ADCIC
b FF98H
CCH
A/D Converter End of Conversion
Interrupt Control Register
0000H
ADCON
b FFA0H
D0H
A/D Converter Control Register
0000H
ADDAT
FEA0H
50H
A/D Converter Result Register
0000H
ADDAT2
F0A0H
E 50H
A/D Converter 2 Result Register
0000H
ADDRSEL1
FE18H
0CH
Address Select Register 1
0000H
ADDRSEL2
FE1AH
0DH
Address Select Register 2
0000H
ADDRSEL3
FE1CH
0EH
Address Select Register 3
0000H
ADDRSEL4
FE1EH
0FH
Address Select Register 4
0000H
b FF9AH
CDH
A/D Converter Overrun Error Interrupt
Control Register
0000H
BUSCON0 b FF0CH
86H
Bus Configuration Register 0
0000H
BUSCON1 b FF14H
8AH
Bus Configuration Register 1
0000H
BUSCON2 b FF16H
8BH
Bus Configuration Register 2
0000H
BUSCON3 b FF18H
8CH
Bus Configuration Register 3
0000H
BUSCON4 b FF1AH
8DH
Bus Configuration Register 4
0000H
ADEIC
C1BTR
EF04H
X ---
CAN1 Bit Timing Register
C1CSR
EF00H
X ---
CAN1 Control / Status Register
C1GMS
EF06H
X ---
CAN1 Global Mask Short
C1LARn
EFn4H
X ---
CAN Lower Arbitration Register (msg. n) UUUUH
C1LGML
EF0AH
X ---
CAN Lower Global Mask Long
UUUUH
C1LMLM
EF0EH
X ---
CAN Lower Mask of Last Message
UUUUH
C1MCFGn
EFn6H
X ---
CAN Message Configuration Register
(msg. n)
User’s Manual
23-4
UUUUH
XX01H
UFUUH
UUH
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-3
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
8-Bit Description
Addr.
Reset
Value
C1MCRn
EFn0H
X ---
CAN Message Control Register (msg. n) UUUUH
C1PCIR
EF02H
X ---
CAN1 Port Control / Interrupt Register
C1UARn
EFn2H
X ---
CAN Upper Arbitration Register (msg. n) UUUUH
C1UGML
EF08H
X ---
CAN Upper Global Mask Long
UUUUH
C1UMLM
EF0CH
X ---
CAN Upper Mask of Last Message
UUUUH
XXXXH
CC10IC
b FF8CH
C6H
External Interrupt 2 Control Register
0000H
CC11IC
b FF8EH
C7H
External Interrupt 3 Control Register
0000H
FE60H
30H
CAPCOM Register 16
0000H
b F160H
E B0H
CAPCOM Reg. 16 Interrupt Ctrl. Reg.
0000H
FE62H
31H
CAPCOM Register 17
0000H
b F162H
E B1H
CAPCOM Reg. 17 Interrupt Ctrl. Reg.
0000H
FE64H
32H
CAPCOM Register 18
0000H
b F164H
E B2H
CAPCOM Reg. 18 Interrupt Ctrl. Reg.
0000H
FE66H
33H
CAPCOM Register 19
0000H
b F166H
E B3H
CAPCOM Reg. 19 Interrupt Ctrl. Reg.
0000H
CC20
FE68H
34H
CAPCOM Register 20
0000H
CC21
FE6AH
35H
CAPCOM Register 21
0000H
CC22
FE6CH
36H
CAPCOM Register 22
0000H
CC23
FE6EH
37H
CAPCOM Register 23
0000H
CC24
FE70H
38H
CAPCOM Register 24
0000H
b F170H
E B8H
CAPCOM Reg. 24 Interrupt Ctrl. Reg.
0000H
FE72H
39H
CAPCOM Register 25
0000H
b F172H
E B9H
CAPCOM Reg. 25 Interrupt Ctrl. Reg.
0000H
FE74H
3AH
CAPCOM Register 26
0000H
b F174H
E BAH
CAPCOM Reg. 26 Interrupt Ctrl. Reg.
0000H
FE76H
3BH
CAPCOM Register 27
0000H
b F176H
E BBH
CAPCOM Reg. 27 Interrupt Ctrl. Reg.
0000H
CC28
FE78H
3CH
CAPCOM Register 28
0000H
CC29
FE7AH
3DH
CAPCOM Register 29
0000H
CC30
FE7CH
3EH
CAPCOM Register 30
0000H
CC16
CC16IC
CC17
CC17IC
CC18
CC18IC
CC19
CC19IC
CC24IC
CC25
CC25IC
CC26
CC26IC
CC27
CC27IC
User’s Manual
23-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-3
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
8-Bit Description
Addr.
Reset
Value
CC31
FE7EH
3FH
CAPCOM Register 31
0000H
CC60
FE30H
18H
CAPCOM 6 Register 0
0000H
CC61
FE32H
19H
CAPCOM 6 Register 1
0000H
CC62
FE34H
1AH
CAPCOM 6 Register 2
0000H
CC6EIC
b F188H
E C4H
CAPCOM 6 Emergency Interrupt
Control Register
0000H
CC6CIC
b F17EH
E BFH
CAPCOM 6 Interrupt Control Register
0000H
CC6MCON b FF32H
99H
CAPCOM 6 Mode Control Register
00FFH
CC6MIC
b FF36H
9BH
CAPCOM 6 Mode Interrupt Ctrl. Reg.
0000H
F036H
E 1BH
CAPCOM 6 Mode Select Register
0000H
CC8IC
b FF88H
C4H
External Interrupt 0 Control Register
0000H
CC9IC
b FF8AH
C5H
External Interrupt 1 Control Register
0000H
CCM4
b FF22H
91H
CAPCOM Mode Control Register 4
0000H
CCM5
b FF24H
92H
CAPCOM Mode Control Register 5
0000H
CCM6
b FF26H
93H
CAPCOM Mode Control Register 6
0000H
CCM7
b FF28H
94H
CAPCOM Mode Control Register 7
0000H
CMP13
FE36H
1BH
CAPCOM 6 Timer 13 Compare Reg.
0000H
CP
FE10H
08H
CPU Context Pointer Register
FC00H
CSP
FE08H
04H
CPU Code Segment Pointer Register
(8 bits, not directly writeable)
0000H
CTCON
b FF30H
98H
CAPCOM 6 Compare Timer Ctrl. Reg.
1010H
DP0H
b F102H
E 81H
P0H Direction Control Register
00H
DP0L
b F100H
E 80H
P0L Direction Control Register
00H
DP1H
b F106H
E 83H
P1H Direction Control Register
00H
DP1L
b F104H
E 82H
P1L Direction Control Register
00H
DP20
b FFB6H
DBH
Port 20 Direction Control Register
00H
DP8
b FFD6H
EBH
Port 8 Direction Control Register
00H
DPP0
FE00H
00H
CPU Data Page Pointer 0 Reg. (10 bits)
0000H
DPP1
FE02H
01H
CPU Data Page Pointer 1 Reg. (10 bits)
0001H
DPP2
FE04H
02H
CPU Data Page Pointer 2 Reg. (10 bits)
0002H
CC6MSEL
User’s Manual
23-6
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-3
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
8-Bit Description
Addr.
Reset
Value
DPP3
FE06H
03H
CPU Data Page Pointer 3 Reg. (10 bits)
0003H
EXICON
b F1C0H
E E0H
External Interrupt Control Register
0000H
EXISEL
b F1DAH
E EDH
External Interrupt Source Select Reg.
0000H
FOCON
b FFAAH
D5H
Frequency Output Control Register
0000H
IDCHIP
F07CH
E 3EH
Identifier
XXXXH
IDMANUF
F07EH
E 3FH
Identifier
1820H
IDMEM
F07AH
E 3DH
Identifier
X008H
IDPROG
F078H
E 3CH
Identifier
XXXXH
IDMEM2
F076H
E 3BH
Identifier
0000H
ISNC
b F1DEH
E EFH
Interrupt Subnode Control Register
0000H
MDC
b FF0EH
87H
CPU Multiply Divide Control Register
0000H
MDH
FE0CH
06H
CPU Multiply Divide Reg. – High Word
0000H
MDL
FE0EH
07H
CPU Multiply Divide Reg. – Low Word
0000H
ODP8
b F1D6H
E EBH
ONES
b FF1EH
8FH
Port 8 Open Drain Control Register
00H
Constant Value 1’s Register (read only)
FFFFH
OPAD
EDC2H X ---
OTP Progr. Interface Address Register
0000H
OPCTRL
EDC0H X ---
OTP Progr. Interface Control Register
0007H
OPDAT
EDC4H X ---
OTP Progr. Interface Data Register
0000H
P0H
b FF02H
81H
Port 0 High Reg. (Upper half of PORT0)
00H
P0L
b FF00H
80H
Port 0 Low Reg. (Lower half of PORT0)
00H
P1H
b FF06H
83H
Port 1 High Reg. (Upper half of PORT1)
00H
P1L
b FF04H
82H
Port 1 Low Reg. (Lower half of PORT1)
00H
P5
b FFA2H
D1H
Port 5 Register (read only)
P5DIDIS
b FFA4H
D2H
Port 5 Digital Input Disable Register
P20
b FFB4H
DAH
Port 20 Register (6 bits)
00H
P8
b FFD4H
EAH
Port 8 Register (4 bits)
00H
PECC0
FEC0H
60H
PEC Channel 0 Control Register
0000H
PECC1
FEC2H
61H
PEC Channel 1 Control Register
0000H
PECC2
FEC4H
62H
PEC Channel 2 Control Register
0000H
PECC3
FEC6H
63H
PEC Channel 3 Control Register
0000H
User’s Manual
23-7
XXXXH
0000H
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-3
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
8-Bit Description
Addr.
Reset
Value
PECC4
FEC8H
64H
PEC Channel 4 Control Register
0000H
PECC5
FECAH
65H
PEC Channel 5 Control Register
0000H
PECC6
FECCH
66H
PEC Channel 6 Control Register
0000H
PECC7
FECEH
67H
PEC Channel 7 Control Register
0000H
POCON0H
F082H
E 41H
Port P0H Output Control Register
0011H
POCON0L
F080H
E 40H
Port P0L Output Control Register
0011H
POCON1H
F086H
E 43H
Port P1H Output Control Register
0011H
POCON1L
F084H
E 42H
Port P1L Output Control Register
0011H
POCON20
F0AAH
E 55H
Port P20 Output Control Register
0000H
POCON8
F092H
E 49H
Port P8 Output Control Register
0022H
b FF10H
88H
CPU Program Status Word
0000H
PTCR
F0AEH
E 57H
Port Temperature Compensation Reg.
0000H
RP0H
b F108H
E 84H
System Startup Config. Reg. (Rd. only)
RSTCON
b F1E0H m ---
PSW
Reset Control Register
XXH
00XXH
RTCH
F0D6H
E 6BH
RTC High Register
no
RTCL
F0D4H
E 6AH
RTC Low Register
no
S0BG
FEB4H
5AH
Serial Channel 0 Baud Rate Generator
Reload Register
0000H
S0CON
b FFB0H
D8H
Serial Channel 0 Control Register
0000H
S0EIC
b FF70H
B8H
Serial Channel 0 Error Interrupt Ctrl.
Reg.
0000H
FEB2H
59H
Serial Channel 0 Receive Buffer Reg.
(read only)
S0RIC
b FF6EH
B7H
Serial Channel 0 Receive Interrupt
Control Register
0000H
S0TBIC
b F19CH
E CEH
Serial Channel 0 Transmit Buffer
Interrupt Control Register
0000H
FEB0H
58H
Serial Channel 0 Transmit Buffer Reg.
(write only)
0000H
b FF6CH
B6H
Serial Channel 0 Transmit Interrupt
Control Register
0000H
S0RBUF
S0TBUF
S0TIC
User’s Manual
23-8
XXXXH
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-3
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
8-Bit Description
Addr.
SP
FE12H
09H
SSCBR
F0B4H
E 5AH
SSCCON
b FFB2H
SSCEIC
Reset
Value
CPU System Stack Pointer Register
FC00H
SSC Baudrate Register
0000H
D9H
SSC Control Register
0000H
b FF76H
BBH
SSC Error Interrupt Control Register
0000H
SSCRB
F0B2H
E 59H
SSCRIC
b FF74H
BAH
SSCTB
F0B0H
E 58H
SSCTIC
b FF72H
STKOV
STKUN
SYSCON
SSC Receive Buffer
XXXXH
SSC Receive Interrupt Control Register
0000H
SSC Transmit Buffer
0000H
B9H
SSC Transmit Interrupt Control Register
0000H
FE14H
0AH
CPU Stack Overflow Pointer Register
FA00H
FE16H
0BH
CPU Stack Underflow Pointer Register
FC00H
b FF12H
89H
CPU System Configuration Register
1)
0xx0H
SYSCON1 b F1DCH E EEH
CPU System Configuration Register 1
0000H
SYSCON2 b F1D0H
E E8H
CPU System Configuration Register 2
0000H
SYSCON3 b F1D4H
E EAH
CPU System Configuration Register 3
0000H
T12IC
b F190H
E C8H
CAPCOM 6 Timer 12 Interrupt Ctrl. Reg.
0000H
T12OF
F034H
E 1AH
CAPCOM 6 Timer 12 Offset Register
0000H
T12P
F030H
E 18H
CAPCOM 6 Timer 12 Period Register
0000H
E CCH
CAPCOM 6 Timer 13 Interrupt Ctrl. Reg.
0000H
0000H
T13IC
b F198H
T13P
F032H
E 19H
CAPCOM 6 Timer 13 Period Register
T14
F0D2H
E 69H
RTC Timer 14 Register
no
T14REL
F0D0H
E 68H
RTC Timer 14 Reload Register
no
T2
FE40H
20H
GPT1 Timer 2 Register
0000H
T2CON
b FF40H
A0H
GPT1 Timer 2 Control Register
0000H
T2IC
b FF60H
B0H
GPT1 Timer 2 Interrupt Control Register
0000H
FE42H
21H
GPT1 Timer 3 Register
0000H
T3CON
b FF42H
A1H
GPT1 Timer 3 Control Register
0000H
T3IC
b FF62H
B1H
GPT1 Timer 3 Interrupt Control Register
0000H
FE44H
22H
GPT1 Timer 4 Register
0000H
T4CON
b FF44H
A2H
GPT1 Timer 4 Control Register
0000H
T4IC
b FF64H
B2H
GPT1 Timer 4 Interrupt Control Register
0000H
T3
T4
User’s Manual
23-9
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-3
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
T7
F050H
E 28H
T78CON
b FF20H
90H
T7IC
b F17AH
T7REL
T8
T8IC
8-Bit Description
Addr.
Reset
Value
CAPCOM Timer 7 Register
0000H
CAPCOM Timer 7 and 8 Ctrl. Reg.
0000H
E BDH
CAPCOM Timer 7 Interrupt Ctrl. Reg.
0000H
F054H
E 2AH
CAPCOM Timer 7 Reload Register
0000H
F052H
E 29H
CAPCOM Timer 8 Register
0000H
b F17CH
E BEH
CAPCOM Timer 8 Interrupt Ctrl. Reg.
0000H
F056H
E 2BH
CAPCOM Timer 8 Reload Register
0000H
T8REL
TFR
b FFACH
D6H
Trap Flag Register
0000H
TRCON
b FF34H
9AH
CAPCOM 6 Trap Enable Ctrl. Reg.
00XXH
WDT
FEAEH
57H
Watchdog Timer Register (read only)
0000H
WDTCON
FFAEH
D7H
Watchdog Timer Control Register
XP0IC
b F186H
E C3H
CAN1 Module Interrupt Control Register
0000H
XP1IC
b F18EH
E C7H
Unassigned Interrupt Control Reg.
0000H
XP3IC
b F19EH
E CFH
PLL/RTC Interrupt Control Register
0000H
ZEROS
b FF1CH
8EH
Constant Value 0’s Register (read only)
0000H
1)
The system configuration is selected during reset.
2)
The reset value depends on the indicated reset source.
User’s Manual
23-10
2)
00xxH
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
23.4
Registers Ordered by Address
Table 23-4 lists all registers implemented in the C164CM ordered by their physical
address. The following markings assist in classifying the listed registers:
“b” in the “Name” column marks Bit-addressable SFRs.
“E” in the “Physical Address” column marks (E)SFRs in the Extended SFR-Space.
“m” in the “Physical Address” column marks SFRs without short 8-bit address.
“X” in the “Physical Address” column marks registers within on-chip X-Peripherals.
Table 23-4
C164CM Registers, Ordered by Name
Name
Physical
Address
OPCTRL
EDC0H X ---
OTP Progr. Interface Control Register
0007H
OPAD
EDC2H X ---
OTP Progr. Interface Address Register
0000H
OPDAT
EDC4H X ---
OTP Progr. Interface Data Register
0000H
C1CSR
EF00H
X ---
CAN1 Control / Status Register
XX01H
C1PCIR
EF02H
X ---
CAN1 Port Control / Interrupt Register
XXXXH
C1BTR
EF04H
X ---
CAN1 Bit Timing Register
UUUUH
C1GMS
EF06H
X ---
CAN1 Global Mask Short
UFUUH
C1UGML
EF08H
X ---
CAN Upper Global Mask Long
UUUUH
C1LGML
EF0AH
X ---
CAN Lower Global Mask Long
UUUUH
C1UMLM
EF0CH
X ---
CAN Upper Mask of Last Message
UUUUH
C1LMLM
EF0EH
X ---
CAN Lower Mask of Last Message
UUUUH
C1MCRn
EFn0H
X ---
CAN Message Control Register (msg. n) UUUUH
C1UARn
EFn2H
X ---
CAN Upper Arbitration Register (msg. n) UUUUH
C1LARn
EFn4H
X ---
CAN Lower Arbitration Register (msg. n) UUUUH
C1MCFGn
EFn6H
X ---
CAN Message Configuration Register
(msg. n)
UUH
T12P
F030H
E 18H
CAPCOM 6 Timer 12 Period Register
0000H
T13P
F032H
E 19H
CAPCOM 6 Timer 13 Period Register
0000H
T12OF
F034H
E 1AH
CAPCOM 6 Timer 12 Offset Register
0000H
CC6MSEL
F036H
E 1BH
CAPCOM 6 Mode Select Register
0000H
T7
F050H
E 28H
CAPCOM Timer 7 Register
0000H
T8
F052H
E 29H
CAPCOM Timer 8 Register
0000H
T7REL
F054H
E 2AH
CAPCOM Timer 7 Reload Register
0000H
User’s Manual
8-Bit Description
Addr.
23-11
Reset
Value
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-4
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
T8REL
F056H
E 2BH
CAPCOM Timer 8 Reload Register
0000H
IDMEM2
F076H
E 3BH
Identifier
0000H
IDPROG
F078H
E 3CH
Identifier
XXXXH
IDMEM
F07AH
E 3DH
Identifier
X008H
IDCHIP
F07CH
E 3EH
Identifier
XXXXH
IDMANUF
F07EH
E 3FH
Identifier
1820H
POCON0L
F080H
E 40H
Port P0L Output Control Register
0011H
POCON0H
F082H
E 41H
Port P0H Output Control Register
0011H
POCON1L
F084H
E 42H
Port P1L Output Control Register
0011H
POCON1H
F086H
E 43H
Port P1H Output Control Register
0011H
POCON8
F092H
E 49H
Port P8 Output Control Register
0022H
ADDAT2
F0A0H
E 50H
A/D Converter 2 Result Register
0000H
POCON20
F0AAH
E 55H
Port P20 Output Control Register
0000H
PTCR
F0AEH
E 57H
Port Temperature Compensation Reg.
0000H
SSCTB
F0B0H
E 58H
SSC Transmit Buffer
0000H
SSCRB
F0B2H
E 59H
SSC Receive Buffer
XXXXH
SSCBR
F0B4H
E 5AH
SSC Baudrate Register
T14REL
F0D0H
E 68H
RTC Timer 14 Reload Register
no
T14
F0D2H
E 69H
RTC Timer 14 Register
no
RTCL
F0D4H
E 6AH
RTC Low Register
no
RTCH
F0D6H
E 6BH
RTC High Register
no
DP0L
b F100H
E 80H
P0L Direction Control Register
00H
DP0H
b F102H
E 81H
P0H Direction Control Register
00H
DP1L
b F104H
E 82H
P1L Direction Control Register
00H
DP1H
b F106H
E 83H
P1H Direction Control Register
00H
RP0H
b F108H
E 84H
System Startup Config. Reg. (Rd. only)
XXH
CC16IC
b F160H
E B0H
CAPCOM Reg. 16 Interrupt Ctrl. Reg.
0000H
CC17IC
b F162H
E B1H
CAPCOM Reg. 17 Interrupt Ctrl. Reg.
0000H
CC18IC
b F164H
E B2H
CAPCOM Reg. 18 Interrupt Ctrl. Reg.
0000H
CC19IC
b F166H
E B3H
CAPCOM Reg. 19 Interrupt Ctrl. Reg.
0000H
User’s Manual
8-Bit Description
Addr.
23-12
Reset
Value
0000H
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-4
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
8-Bit Description
Addr.
Reset
Value
CC24IC
b F170H
E B8H
CAPCOM Reg. 24 Interrupt Ctrl. Reg.
0000H
CC25IC
b F172H
E B9H
CAPCOM Reg. 25 Interrupt Ctrl. Reg.
0000H
CC26IC
b F174H
E BAH
CAPCOM Reg. 26 Interrupt Ctrl. Reg.
0000H
CC27IC
b F176H
E BBH
CAPCOM Reg. 27 Interrupt Ctrl. Reg.
0000H
T7IC
b F17AH
E BDH
CAPCOM Timer 7 Interrupt Ctrl. Reg.
0000H
T8IC
b F17CH
E BEH
CAPCOM Timer 8 Interrupt Ctrl. Reg.
0000H
CC6CIC
b F17EH
E BFH
CAPCOM 6 Interrupt Control Register
0000H
XP0IC
b F186H
E C3H
CAN1 Module Interrupt Control Register
0000H
CC6EIC
b F188H
E C4H
CAPCOM 6 Emergency Interrupt
Control Register
0000H
XP1IC
b F18EH
E C7H
Unassigned Interrupt Control Reg.
0000H
T12IC
b F190H
E C8H
CAPCOM 6 Timer 12 Interrupt Ctrl. Reg.
0000H
T13IC
b F198H
E CCH
CAPCOM 6 Timer 13 Interrupt Ctrl. Reg.
0000H
S0TBIC
b F19CH
E CEH
Serial Channel 0 Transmit Buffer
Interrupt Control Register
0000H
XP3IC
b F19EH
E CFH
PLL/RTC Interrupt Control Register
0000H
EXICON
b F1C0H
E E0H
External Interrupt Control Register
0000H
SYSCON2 b F1D0H
E E8H
CPU System Configuration Register 2
0000H
SYSCON3 b F1D4H
E EAH
CPU System Configuration Register 3
0000H
ODP8
b F1D6H
E EBH
Port 8 Open Drain Control Register
EXISEL
b F1DAH
E EDH
External Interrupt Source Select Reg.
0000H
SYSCON1 b F1DCH E EEH
CPU System Configuration Register 1
0000H
ISNC
b F1DEH
Interrupt Subnode Control Register
0000H
RSTCON
b F1E0H m ---
Reset Control Register
00XXH
E EFH
00H
DPP0
FE00H
00H
CPU Data Page Pointer 0 Reg. (10 bits)
0000H
DPP1
FE02H
01H
CPU Data Page Pointer 1 Reg. (10 bits)
0001H
DPP2
FE04H
02H
CPU Data Page Pointer 2 Reg. (10 bits)
0002H
DPP3
FE06H
03H
CPU Data Page Pointer 3 Reg. (10 bits)
0003H
CSP
FE08H
04H
CPU Code Segment Pointer Register
(8 bits, not directly writeable)
0000H
User’s Manual
23-13
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-4
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
8-Bit Description
Addr.
Reset
Value
MDH
FE0CH
06H
CPU Multiply Divide Reg. – High Word
0000H
MDL
FE0EH
07H
CPU Multiply Divide Reg. – Low Word
0000H
CP
FE10H
08H
CPU Context Pointer Register
FC00H
SP
FE12H
09H
CPU System Stack Pointer Register
FC00H
STKOV
FE14H
0AH
CPU Stack Overflow Pointer Register
FA00H
STKUN
FE16H
0BH
CPU Stack Underflow Pointer Register
FC00H
ADDRSEL1
FE18H
0CH
Address Select Register 1
0000H
ADDRSEL2
FE1AH
0DH
Address Select Register 2
0000H
ADDRSEL3
FE1CH
0EH
Address Select Register 3
0000H
ADDRSEL4
FE1EH
0FH
Address Select Register 4
0000H
CC60
FE30H
18H
CAPCOM 6 Register 0
0000H
CC61
FE32H
19H
CAPCOM 6 Register 1
0000H
CC62
FE34H
1AH
CAPCOM 6 Register 2
0000H
CMP13
FE36H
1BH
CAPCOM 6 Timer 13 Compare Reg.
0000H
T2
FE40H
20H
GPT1 Timer 2 Register
0000H
T3
FE42H
21H
GPT1 Timer 3 Register
0000H
T4
FE44H
22H
GPT1 Timer 4 Register
0000H
CC16
FE60H
30H
CAPCOM Register 16
0000H
CC17
FE62H
31H
CAPCOM Register 17
0000H
CC18
FE64H
32H
CAPCOM Register 18
0000H
CC19
FE66H
33H
CAPCOM Register 19
0000H
CC20
FE68H
34H
CAPCOM Register 20
0000H
CC21
FE6AH
35H
CAPCOM Register 21
0000H
CC22
FE6CH
36H
CAPCOM Register 22
0000H
CC23
FE6EH
37H
CAPCOM Register 23
0000H
CC24
FE70H
38H
CAPCOM Register 24
0000H
CC25
FE72H
39H
CAPCOM Register 25
0000H
CC26
FE74H
3AH
CAPCOM Register 26
0000H
CC27
FE76H
3BH
CAPCOM Register 27
0000H
CC28
FE78H
3CH
CAPCOM Register 28
0000H
User’s Manual
23-14
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-4
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
8-Bit Description
Addr.
Reset
Value
CC29
FE7AH
3DH
CAPCOM Register 29
0000H
CC30
FE7CH
3EH
CAPCOM Register 30
0000H
CC31
FE7EH
3FH
CAPCOM Register 31
0000H
ADDAT
FEA0H
50H
A/D Converter Result Register
0000H
WDT
FEAEH
57H
Watchdog Timer Register (read only)
0000H
S0TBUF
FEB0H
58H
Serial Channel 0 Transmit Buffer Reg.
(write only)
0000H
S0RBUF
FEB2H
59H
Serial Channel 0 Receive Buffer Reg.
(read only)
XXXXH
S0BG
FEB4H
5AH
Serial Channel 0 Baud Rate Generator
Reload Register
0000H
PECC0
FEC0H
60H
PEC Channel 0 Control Register
0000H
PECC1
FEC2H
61H
PEC Channel 1 Control Register
0000H
PECC2
FEC4H
62H
PEC Channel 2 Control Register
0000H
PECC3
FEC6H
63H
PEC Channel 3 Control Register
0000H
PECC4
FEC8H
64H
PEC Channel 4 Control Register
0000H
PECC5
FECAH
65H
PEC Channel 5 Control Register
0000H
PECC6
FECCH
66H
PEC Channel 6 Control Register
0000H
PECC7
FECEH
67H
PEC Channel 7 Control Register
0000H
P0L
b FF00H
80H
Port 0 Low Reg. (Lower half of PORT0)
00H
P0H
b FF02H
81H
Port 0 High Reg. (Upper half of PORT0)
00H
P1L
b FF04H
82H
Port 1 Low Reg. (Lower half of PORT1)
00H
P1H
b FF06H
83H
Port 1 High Reg. (Upper half of PORT1)
00H
BUSCON0 b FF0CH
86H
Bus Configuration Register 0
0000H
MDC
b FF0EH
87H
CPU Multiply Divide Control Register
0000H
PSW
b FF10H
88H
CPU Program Status Word
0000H
SYSCON
b FF12H
89H
CPU System Configuration Register
BUSCON1 b FF14H
8AH
Bus Configuration Register 1
0000H
BUSCON2 b FF16H
8BH
Bus Configuration Register 2
0000H
BUSCON3 b FF18H
8CH
Bus Configuration Register 3
0000H
User’s Manual
23-15
1)
0xx0H
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-4
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
8-Bit Description
Addr.
Reset
Value
BUSCON4 b FF1AH
8DH
Bus Configuration Register 4
0000H
ZEROS
b FF1CH
8EH
Constant Value 0’s Register (read only)
0000H
ONES
b FF1EH
8FH
Constant Value 1’s Register (read only)
FFFFH
T78CON
b FF20H
90H
CAPCOM Timer 7 and 8 Ctrl. Reg.
0000H
CCM4
b FF22H
91H
CAPCOM Mode Control Register 4
0000H
CCM5
b FF24H
92H
CAPCOM Mode Control Register 5
0000H
CCM6
b FF26H
93H
CAPCOM Mode Control Register 6
0000H
CCM7
b FF28H
94H
CAPCOM Mode Control Register 7
0000H
CTCON
b FF30H
98H
CAPCOM 6 Compare Timer Ctrl. Reg.
1010H
CC6MCON b FF32H
99H
CAPCOM 6 Mode Control Register
00FFH
TRCON
b FF34H
9AH
CAPCOM 6 Trap Enable Ctrl. Reg.
00XXH
CC6MIC
b FF36H
9BH
CAPCOM 6 Mode Interrupt Ctrl. Reg.
0000H
T2CON
b FF40H
A0H
GPT1 Timer 2 Control Register
0000H
T3CON
b FF42H
A1H
GPT1 Timer 3 Control Register
0000H
T4CON
b FF44H
A2H
GPT1 Timer 4 Control Register
0000H
T2IC
b FF60H
B0H
GPT1 Timer 2 Interrupt Control Register
0000H
T3IC
b FF62H
B1H
GPT1 Timer 3 Interrupt Control Register
0000H
T4IC
b FF64H
B2H
GPT1 Timer 4 Interrupt Control Register
0000H
S0TIC
b FF6CH
B6H
Serial Channel 0 Transmit Interrupt
Control Register
0000H
S0RIC
b FF6EH
B7H
Serial Channel 0 Receive Interrupt
Control Register
0000H
S0EIC
b FF70H
B8H
Serial Channel 0 Error Interrupt Ctrl.
Reg.
0000H
SSCTIC
b FF72H
B9H
SSC Transmit Interrupt Control Register
0000H
SSCRIC
b FF74H
BAH
SSC Receive Interrupt Control Register
0000H
SSCEIC
b FF76H
BBH
SSC Error Interrupt Control Register
0000H
CC8IC
b FF88H
C4H
External Interrupt 0 Control Register
0000H
CC9IC
b FF8AH
C5H
External Interrupt 1 Control Register
0000H
CC10IC
b FF8CH
C6H
External Interrupt 2 Control Register
0000H
User’s Manual
23-16
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
Table 23-4
C164CM Registers, Ordered by Name (cont’d)
Name
Physical
Address
8-Bit Description
Addr.
Reset
Value
CC11IC
b FF8EH
C7H
External Interrupt 3 Control Register
0000H
ADCIC
b FF98H
CCH
A/D Converter End of Conversion
Interrupt Control Register
0000H
ADEIC
b FF9AH
CDH
A/D Converter Overrun Error Interrupt
Control Register
0000H
ADCON
b FFA0H
D0H
A/D Converter Control Register
0000H
P5
b FFA2H
D1H
Port 5 Register (read only)
P5DIDIS
b FFA4H
D2H
Port 5 Digital Input Disable Register
0000H
FOCON
b FFAAH
D5H
Frequency Output Control Register
0000H
TFR
b FFACH
D6H
Trap Flag Register
0000H
FFAEH
D7H
Watchdog Timer Control Register
S0CON
b FFB0H
D8H
Serial Channel 0 Control Register
0000H
SSCCON
b FFB2H
D9H
SSC Control Register
0000H
P20
b FFB4H
DAH
Port 20 Register (6 bits)
00H
DP20
b FFB6H
DBH
Port 20 Direction Control Register
00H
P8
b FFD4H
EAH
Port 8 Register (4 bits)
00H
DP8
b FFD6H
EBH
Port 8 Direction Control Register
00H
WDTCON
1)
The system configuration is selected during reset.
2)
The reset value depends on the indicated reset source.
User’s Manual
23-17
XXXXH
2)
00xxH
V1.0, 2002-02
C164CM/C164SM
Derivatives
Register Set
23.5
Special Notes
PEC Pointer Registers
The source and destination pointers for the Peripheral Event Controller (PEC) are
mapped to a special area within the internal RAM. Pointers not occupied by the PEC may
be used like normal RAM. During Power Down mode or any warm reset, the PEC
pointers are preserved.
The PEC and its registers are described in Chapter 5.
GPR Access in the ESFR Area
The locations 00’F000H … 00’F01EH within the ESFR area are reserved and allow to
access the current register bank via short register addressing modes. The GPRs are
mirrored to the ESFR area to allow access to the current register bank even after
switching register spaces (see example below).
MOV
EXTR
MOV
R5, DP8
#1
R5, ODP8
;GPR access via SFR area
;GPR access via ESFR area
Writing Bytes to SFRs
All Special Function Registers may be accessed wordwise or bytewise (some of them
even bitwise). Reading bytes from word SFRs is a non-critical operation. However, when
writing bytes to word SFRs, the complementary byte of the respective SFR is cleared
with the write operation.
User’s Manual
23-18
V1.0, 2002-02
C164CM/C164SM
Derivatives
Instruction Set Summary
24
Instruction Set Summary
This chapter briefly summarizes the C164CM’s instructions by instruction classes. This
provides a basic description of the C164CM’s instruction set, the power and versatility of
the instructions, and their general usage.
Detailed descriptions of each individual instruction, including its operand data type,
condition flag settings, addressing modes, length (number of bytes), and object code
format are provided in the “Instruction Set Manual” for the C166 Family. This manual
also provides tables listing the instructions according to various criteria to facilitate quick
information access.
Summary of Instruction Classes
Grouping the various instructions into classes assists in identifying similar instructions
(such as SHR, ROR) and variations of instructions (such as ADD, ADDB). This provides
an easy access to the possibilities and power of the instructions of the C164CM.
Note: The used mnemonics refer to the detailed description.
Arithmetic Instructions
•
•
•
•
•
•
•
•
•
Addition of two words or bytes:
Addition with Carry of two words or bytes:
Subtraction of two words or bytes:
Subtraction with Carry of two words or bytes:
16 ×16 bit signed or unsigned multiplication:
16 / 16 bit signed or unsigned division:
32 / 16 bit signed or unsigned division:
1’s complement of a word or byte:
2’s complement (negation) of a word or byte:
ADD
ADDC
SUB
SUBC
MUL
DIV
DIVL
CPL
NEG
ADDB
ADDCB
SUBB
SUBCB
MULU
DIVU
DIVLU
CPLB
NEGB
AND
OR
XOR
ANDB
ORB
XORB
CMP
CMPB
CMPI1
CMPI2
CMPD1
CMPD2
Logical Instructions
• Bitwise ANDing of two words or bytes:
• Bitwise ORing of two words or bytes:
• Bitwise XORing of two words or bytes:
Compare and Loop Control Instructions
• Comparison of two words or bytes:
• Comparison of two words with post-increment
by either 1 or 2:
• Comparison of two words with post-decrement
by either 1 or 2:
User’s Manual
24-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Instruction Set Summary
Boolean Bit Manipulation Instructions
• Manipulation of a maskable bit field
in either the high or the low byte of a word:
• Setting a single bit (to ‘1’):
• Clearing a single bit (to ‘0’):
• Movement of a single bit:
• Movement of a negated bit:
• ANDing of two bits:
• ORing of two bits:
• XORing of two bits:
• Comparison of two bits:
BFLDH
BSET
BCLR
BMOV
BMOVN
BAND
BOR
BXOR
BCMP
BFLDL
Shift and Rotate Instructions
•
•
•
•
•
Shifting right of a word:
Shifting left of a word:
Rotating right of a word:
Rotating left of a word:
Arithmetic shifting right of a word (sign bit shifting):
SHR
SHL
ROR
ROL
ASHR
Prioritize Instruction
• Determination of the number of shift cycles required
to normalize a word operand (floating point support): PRIOR
Data Movement Instructions
• Standard data movement of a word or byte:
• Data movement of a byte to a word location
with either sign or zero byte extension:
MOV
MOVB
MOVBS
MOVBZ
Note: The data movement instructions can be used with a variety of different addressing
modes including indirect addressing and automatic pointer in-/decrementing.
System Stack Instructions
• Pushing a word onto the system stack:
• Popping a word from the system stack:
• Saving a word on the system stack,
and then updating the old word with a new value
(provided for register bank switching):
User’s Manual
24-2
PUSH
POP
SCXT
V1.0, 2002-02
C164CM/C164SM
Derivatives
Instruction Set Summary
Jump Instructions
• Conditional jumping to either an absolutely,
indirectly, or relatively addressed target instruction
within the current code segment:
• Unconditional jumping to an absolutely addressed
target instruction within any code segment:
• Conditional jumping to a relatively addressed
target instruction within the current code segment
depending on the state of a selectable bit:
• Conditional jumping to a relatively addressed
target instruction within the current code segment
depending on the state of a selectable bit
with a post-inversion of the tested bit
in the case of a jump taken (semaphore support):
JMPA
JMPI
JMPR
JMPS
JB
JNB
JBC
JNBS
Call Instructions
• Conditional calling of either an absolutely
or indirectly addressed subroutine within the current
code segment:
CALLA
• Unconditional calling of a relatively addressed
subroutine within the current code segment:
CALLR
• Unconditional calling of an absolutely addressed
subroutine within any code segment:
CALLS
• Unconditional calling of an absolutely addressed
subroutine within the current code segment plus
an additional pushing of a selectable register onto
the system stack:
PCALL
• Unconditional branching to the interrupt or
trap vector jump table in code segment 0:
TRAP
CALLI
Return Instructions
• Returning from a subroutine
within the current code segment:
• Returning from a subroutine
within any code segment:
• Returning from a subroutine within the current
code segment plus an additional popping of a
selectable register from the system stack:
• Returning from an interrupt service routine:
User’s Manual
24-3
RET
RETS
RETP
RETI
V1.0, 2002-02
C164CM/C164SM
Derivatives
Instruction Set Summary
System Control Instructions
•
•
•
•
•
•
Resetting the C164CM via software:
Entering the Idle mode:
Entering the Power Down mode:
Servicing the Watchdog Timer:
Disabling the Watchdog Timer:
Signifying the end of the initialization routine
(pulls pin RSTOUT high, and disables the effect of
any later execution of a DISWDT instruction):
SRST
IDLE
PWRDN
SRVWDT
DISWDT
EINIT
Miscellaneous
• Null operation which requires two bytes of
storage and the minimum time for execution:
• Definition of an inseparable instruction sequence:
• Switch ‘reg’, ‘bitoff’ and ‘bitaddr’ addressing modes
to the Extended SFR space:
• Override the DPP addressing scheme
using a specific data page instead of the DPPs,
and optionally switch to ESFR space:
• Override the DPP addressing scheme
using a specific segment instead of the DPPs,
and optionally switch to ESFR space:
NOP
ATOMIC
EXTR
EXTP
EXTPR
EXTS
EXTSR
Note: The ATOMIC and EXT* instructions provide support for uninterruptable code
sequences e.g. for semaphore operations. They also support data addressing
beyond the limits of the current DPPs (except ATOMIC). This is advantageous for
larger memory models in high level languages. Refer to Chapter 22 for examples.
Protected Instructions
Some instructions of the C164CM critical for the functionality of the controller are
implemented as so-called Protected Instructions. These protected instructions use the
maximum instruction format of 32 bits for decoding. Regular instructions use only a
portion of it (such as the lower 8 bits), with the other bits providing additional information
such as indicating the involved registers. Decoding all 32 bits of a protected doubleword
instruction increases security in cases of data distortion during instruction fetching.
Critical operations such as a software reset are, therefore, executed only if the complete
instruction is decoded without an error. This enhances the safety and reliability of a
microcontroller system.
User’s Manual
24-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
Device Specification
25
Device Specification
The device specification describes the electrical parameters of the device. It lists DC
characteristics such as input/output voltages, supply voltages, input/output/supply
currents, as well as AC characteristics such as timing characteristics and requirements.
Other than the architecture, the instruction set, or the basic functions of the C164CM
core and its peripherals, these DC and AC characteristics are subject to change due to
device improvements or development of specific derivatives of the standard device.
Therefore, these characteristics are not contained in this User’s Manual, but are
provided in device-specific Data Sheets, which can be updated more frequently.
Please refer to the current version of the Data Sheet of the respective device for all
electrical parameters.
Note: The specific characteristics of a device should always be verified before a new
design is started to ensure use of the most current information.
Figure 25-1 shows the pin diagram of the C164CM. It shows the location of the various
supply and IO pins. Detailed descriptions of all pins are also found in the Data Sheet.
Note: Not all alternate functions shown in Figure 25-1 are supported by all derivatives.
Please refer to the corresponding descriptions in their data sheets.
User’s Manual
25-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
P5.2/AN2/T3EUD
P5.1/AN1
P5.0/AN0
VAREF
VAGND
P8.3/CC19IO/CAN_TxD
P8.2/CC18IO/CAN_RxD
P8.1/CC17IO/CAN_TxD
P8.0/CC16IO/CAN_RxD
P1.15/CC27IO
P1.14/CC26IO
P1.13/CC25IO
P1.12/CC24IO
VSS
XTAL1
XTAL2
Device Specification
P5.3/AN3/T3IN
P5.4/AN4/T2EUD
P5.5/AN5/T4EUD
P5.6/AN6/T2IN
P5.7/AN7/T4IN (TRSEL)
VSS
VDD
VDD
P1.11/EX3IN/T7IN/CC31IO
P1.10/CC6POS2/EX2IN/CC30IO
P1.9/CC6POS1/EX1IN/CC29IO
P1.8/CC6POS0/EX0IN/CC28IO
P1.7/CTRAP
P1.6/COUT63
P1.5/COUT62
P1.4/CC62
P1.3/COUT61
P1.2/CC61
P1.1/COUT60
P1.0/CC60
P20.12/RSTOUT
P20.8/CLKOUT/FOUT
VSS
VSS
P0.7/AD7
P0.6/AD6
P0.5/AD5
P0.4/AD4
P0.3/AD3
P0.2/AD2
P0.1/AD1
P0.0/AD0
NMI
RSTIN
P20.0/RD
P20.1/WR
P20.4/ALE
P20.5/EA/Vpp
VDD
P0.15/AD15/SCLK
P0.14/AD14/MTSR
P0.13/AD13/MRST
P0.12/AD12/RxD0
P0.11/AD11/TxD0
P0.10/AD10
P0.9/AD9
P0.8/AD8
VDD
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
1
48
2
47
46
3
4
45
44
5
6
43
7
42
41
8
C164CM
40
9
10
39
11
38
37
12
13
36
14
35
15
34
16
33
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
MCP04955
Figure 25-1 Pin Configuration for C164CM, P-MQFP-80 Package
Note: Port 8 pins can have CAN interface lines assigned to them. Chapter 19 lists the
possible assignments.
User’s Manual
25-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
Keyword Index
26
Keyword Index
This section lists a number of keywords which refer to specific details of the C164CM in
terms of its architecture, its functional units or functions. This helps to quickly find the
answer to specific questions about the C164CM.
A
Bit
Access to X-Peripherals 9-25
Acronyms 1-8
Adapt Mode 20-15
ADC 2-16, 18-1
ADCIC, ADEIC 18-15
ADCON 18-3
ADDAT, ADDAT2 18-5
Address
Arbitration 9-21
Area Definition 9-20
Boundaries 3-10
ADDRSELx 9-17, 9-21
ALE length 9-10
Alternate signals 7-9
ALU 4-16
Analog/Digital Converter 2-16, 18-1
Arbitration
Address 9-21
ASC0 11-1
Asynchronous mode 11-5
Baudrate 11-11
Error Detection 11-10
Interrupts 11-15
Synchronous mode 11-8
Asynchronous Serial Interface (->ASC0)
11-1
Auto Scan conversion 18-7
addressable memory 3-4
Handling 4-10
Manipulation Instructions 24-2
protected 2-21, 4-10
reserved 2-13
Block Commutation Mode 17-16
Bootstrap Loader 15-1, 20-16
Boundaries 3-10
BTR 19-12
Burst Mode
CAPCOM6 17-10
Bus
CAN 2-15, 19-1, 19-36
Demultiplexed 9-5
Idle State 9-23
Mode Configuration 9-2, 20-17
Mode, preferred 9-3
Multiplexed 9-4
BUSCONx 9-16, 9-21
B
Baudrate
ASC0 11-11
Bootstrap Loader 15-6
SSC 12-13
Bidirectional reset 20-4
User’s Manual
C
CAN Interface 2-15, 19-1
activation 19-31
port control 19-37
CAPCOM 2-18
interrupt 16-22, 16-23
timer 16-4
Trap Function 17-18
unit 16-1, 17-1
Capture Mode
CAPCOM2 16-12
CAPCOM6 17-11
GPT1 10-19
Capture/Compare unit 16-1, 17-1
CC6IC, CC6EIC 17-33
26-1
V1.0, 2002-02
C164CM/C164SM
Derivatives
Keyword Index
CC6MCON 17-26
CC6MIC 17-30
CC6MSEL 17-29
CCM4, CCM5, CCM6, CCM7 16-10
CCxIC 5-28, 16-22
Center Aligned Mode
CAPCOM6 17-7
Clock
distribution 6-2, 21-15
generator modes 6-8, 20-18
output signal 21-17
Code memory handling 22-16
Compare modes 16-14
double register 16-19
Concatenation of Timers 10-16
Configuration
Bus Mode 9-2, 20-17
default 20-19
of pins 25-2
PLL 6-8, 20-18
Reset 20-7, 20-12
special modes 20-16
Context
Pointer 4-25
Switching 5-18
Conversion
Analog/Digital 18-1
Auto Scan 18-7
timing control 18-13
Count direction 10-4
Counter 10-8, 10-14
CP 4-25
CPU 2-3, 4-1
Host Mode (CHM) 3-14
CSP 4-20
CSR 19-7
CTCON 17-23
D
Data Page 4-22, 22-14
boundaries 3-10
Default startup configuration 20-19
Delay
User’s Manual
Read/Write 9-13
Demultiplexed Bus 9-5
Development Support 1-7
Direct Drive 6-7
Direction
count 10-4
Disable
Interrupt 5-15
Peripheral 21-15
Segmentation 4-15
Division 4-30, 22-1
Double-Register compare 16-19
DP0L, DP0H 7-12
DP1L, DP1H 7-17
DP20 7-28
DP8 7-24
DPP 4-22, 22-14
Driver characteristic (ports) 7-4
E
Early WR control 9-13
Edge Aligned Mode
CAPCOM6 17-5
Edge characteristic (ports) 7-4
Emulation Mode 20-14
Enable
Interrupt 5-15
Peripheral 21-15
Segmentation 4-15
XBUS peripherals 9-25
Error Detection
ASC0 11-10
CAN 19-4
SSC 12-15
EXICON 5-27
EXISEL 5-29
External
Bus 2-11
Bus Characteristics 9-9–9-14
Bus Idle State 9-23
Bus Mode, preferred 9-3
Bus Modes 9-2–9-8
Fast interrupts 5-27
26-2
V1.0, 2002-02
C164CM/C164SM
Derivatives
Keyword Index
Host Mode (EHM) 3-15, 20-16
Interrupt source control 5-29
Interrupts 5-25
Interrupts during sleep mode 5-30
startup configuration 20-13
F
Fast external interrupts 5-27
Flags 4-16–4-19
FOCON 21-18
Frequency output signal 21-17
Full-Duplex 12-7
G
GMS 19-15
GPR 3-6, 4-25, 23-2
GPT 2-17
GPT1 10-1
H
Half-Duplex 12-10
Hardware
Reset 20-2
Traps 5-31
I
Idle
Mode 21-4
State (Bus) 9-23
Incremental Interface 10-9
Indication of reset source 13-6
Inseparable instructions 22-14
Instruction 22-1, 24-1
Bit Manipulation 24-2
Branch 4-4
inseparable 22-14
Pipeline 4-3
protected 24-4
Timing 4-11
Interface
CAN 2-15, 19-1
External Bus 9-1
serial async. (->ASC0) 11-1
User’s Manual
serial sync. (->SSC) 12-1
Internal RAM (->IRAM) 3-4
Interrupt
CAPCOM 16-22, 16-23
during sleep mode 5-30
Enable/Disable 5-15
External 5-25
Fast external 5-27
Handling CAN 19-9
Node Sharing 5-24
Priority 5-7
Processing 5-1, 5-5
Response Times 5-19
RTC 14-3
source control 5-29
Sources 5-2
System 2-8, 5-2
Vectors 5-2
IP 4-19
IRAM 3-4
status after reset 20-8
ISNC 5-24
L
LARn 19-21
LGML 19-16
LMLM 19-17
M
Management
Peripheral 21-15
Power 21-1
MCFGn 19-22
MCRn 19-19
MDC 4-32
MDH 4-30
MDL 4-31
Memory 2-9
bit-addressable 3-4
Code memory handling 22-16
Cycle Time 9-11
External 3-9
OTP 3-12
26-3
V1.0, 2002-02
C164CM/C164SM
Derivatives
Keyword Index
RAM/SFR 3-4
ROM area 3-3
Tri-state time 9-12
Multi-Channel Modes (CAPCOM6) 17-12
Multiplexed Bus 9-4
Multiplication 4-30, 22-1
N
NMI 5-1, 5-34
Noise filter (Ext. Interrupts) 5-30
O
ODP8 7-25
ONES 4-33
OPCTRL 3-16
Open Drain Mode 7-3
Oscillator
circuitry 6-3
measurement 6-3
Watchdog 6-9, 20-18
OTP
Programming 3-12
Protection 3-19
P
P0L, P0H 7-11
P1L, P1H 7-16
P20 7-28
P5 7-21
P5DIDIS 7-23
P8 7-24
PCIR 19-10
PEC 2-9, 3-7, 5-11
Response Times 5-22
PECCx 5-11
Peripheral
enable on XBUS 9-25
Enable/Disable 21-15
Management 21-15
Summary 2-12
Phase Locked Loop (->PLL) 6-1
Phase Sequences 17-14
Pins 8-1
User’s Manual
configuration 25-2
in Idle and Power Down mode 21-10
Pipeline 4-3
Effects 4-6
PLL 6-1, 20-18
POCON* 7-5
Port 2-15
driver characteristic 7-4
edge characteristic 7-4
Temperature compensation 7-7
Power Down Mode 21-7
Power Management 2-19, 21-1
Preferred external bus mode 9-3
Prescaler 6-7
Programming
CPU Host Mode 3-14
External Host Mode 3-15
OTP 3-12
Protected
Bits 2-21, 4-10
instruction 24-4
Mask ROM 3-11
OTP memory 3-19
PSW 4-16, 5-9
PTCR 7-8
R
RAM
internal 3-4
Read/Write Delay 9-13
Real Time Clock (->RTC) 14-1
Registers 23-1
sorted by address 23-11
sorted by name 23-4
Reserved bits 2-13
Reset 20-1
Bidirectional 20-4
Configuration 20-7, 20-12
Hardware 20-2
Output 20-8
Software 20-3
Source indication 13-6
Values 20-5
26-4
V1.0, 2002-02
C164CM/C164SM
Derivatives
Keyword Index
Watchdog Timer 20-3
ROM
area 3-3
Protection 3-11
RP0H 9-22
RSTCON 20-22
RTC 2-16, 14-1
S
S0BG 11-11
S0CON 11-2
S0EIC, S0RIC, S0TIC, S0TBIC 11-15
S0RBUF 11-7, 11-9
S0TBUF 11-7, 11-9
Security Mechanism 21-22
Segment
boundaries 3-10
Segmentation 4-20
Enable/Disable 4-15
Serial Interface 2-14, 11-1
Asynchronous (->ASC0) 11-5
CAN 2-15, 19-1
Synchronous 11-8
Synchronous (->SSC) 12-1
SFR 3-8, 23-4, 23-11
Sharing
Interrupt Nodes 5-24
Single Chip Mode 9-2
startup configuration 20-19
Sleep Mode 21-6
Slow Down Mode 21-11
Software
Reset 20-3
system configuration 20-21
Traps 5-31
Source
Interrupt 5-2
Reset 13-6
SP 4-27
Special operation modes (config.) 20-16
SSC 12-1
Baudrate generation 12-13
Error Detection 12-15
User’s Manual
Full-Duplex 12-7
Half-Duplex 12-10
SSCBR 12-13
SSCCON 12-2, 12-4
SSCEIC, SSCRIC, SSCTIC 12-17
SSCRB, SSCTB 12-8
Stack 3-5, 4-27, 22-4
Startup Configuration 20-7, 20-12
external reset 20-13
single-chip 20-19
via software 20-21
STKOV 4-28
STKUN 4-29
Subroutine 22-10
Synchronous Serial Interface (->SSC)
12-1
SYSCON 4-13, 9-15
SYSCON1 21-7
SYSCON2 21-13
SYSCON3 21-16
T
T12IC, T13IC 17-33
T2CON 10-12
T2IC, T3IC, T4IC 10-20
T3CON 10-3
T4CON 10-12
T78CON 16-5
T7IC 16-9
T8IC 16-9
Temperature compensation 7-7
TFR 5-33
Timer 2-17, 10-1
Auxiliary Timer 10-12
CAPCOM2 16-4
CAPCOM6 17-3
Concatenation 10-16
Core Timer 10-3
Tools 1-7
Trap Function (CAPCOM6) 17-18
Traps 5-31
TRCON 17-25
Tri-State Time 9-12
26-5
V1.0, 2002-02
C164CM/C164SM
Derivatives
Keyword Index
U
UARn 19-21
UGML 19-16
UMLM 19-17
Unlock Sequence 21-22
V
Visible mode 9-25
W
Waitstate
Memory Cycle 9-11
Tri-State 9-12
XBUS peripheral 9-25
Watchdog 2-19, 13-1
after reset 20-5
Oscillator 6-9, 20-18
Reset 20-3
WDT 13-2
WDTCON 13-4
X
XBUS 2-11, 9-24
enable peripherals 9-25
external access 9-25
waitstates 9-25
Z
ZEROS 4-33
User’s Manual
26-6
V1.0, 2002-02
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