ST ST72F521, ST72521B User Manual

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ST72F521, ST72521B

80/64-PIN 8-BIT MCU WITH 32 TO 60K FLASH/ROM, ADC,

FIVE TIMERS, SPI, SCI, I

■ Memories

– 32K to 60K dual voltage High Density Flash

(HDFlash) or ROM with read-out protection capability. In-Application Programming and

In-Circuit Programming for HDFlash devices – 1K to 2K RAM – HDFlash endurance: 100 cycles, data reten-

tion: 20 years at 55°C

■ Clock, Reset And Supply Management

– Enhanced low voltage supervisor (LVD) for

main supply and auxiliary voltage detector

(AVD) with interrupt capability – Clock sources: crystal/ceramic resonator os-

cillators, internal RC oscillator and bypass for

external clock – PLL for 2x frequency multiplication – Four power saving modes: Halt, Active-Halt,

Wait and Slow

■ Interrupt Management

– Nested interrupt controller – 14 interrupt vectors plus TRAP and RESET – Top Level Interrupt (TLI) pin – 15 external interrupt lines (on 4 vectors)

■ Up to 64 I/O Ports

– 48 multifunctional bidirectional I/O lines – 34 alternate function lines – 16 high sink outputs

■ 5 Timers

– Main Clock Controller with: Real time base,

Beep and Clock-out capabilities – Configurable watchdog timer – Two 16-bit timers with: 2 input captures, 2 out-

put compares, external clock input on one tim-

er, PWM and pulse generator modes – 8-bit PWM Auto-Reload timer with: 2 input

captures, 4 PWM outputs, output compare

and time base interrupt, external clock with

event detector

TQFP80

14 x 14

■ 4 Communications Interfaces

– SPI synchronous serial interface – SCI asynchronous serial interface

C multimaster interface

–I

(SMbus V1.1 compliant)

– CAN interface (2.0B Passive)

■ Analog periperal (low current coupling)

– 10-bit ADC with 16 input robust input ports

■ Instruction Set

– 8-bit Data Manipulation – 63 Basic Instructions – 17 main Addressing Modes – 8 x 8 Unsigned Multiply Instruction

■ Development Tools

– Full hardware/software development package – In-Circuit Testing capability

C, CAN INTERFACE

TQFP64

14 x 14

TQFP64

10 x 10

Device Summary

Features ST72F521(M/R/AR)9 ST72F521(R/AR)6 ST72521B(M/R/AR)9 ST72521B(R/AR)6

Program memory - bytes Flash 60K Flash 32K ROM 60K ROM 32K RAM (stack) - bytes 2048 (256) 1024 (256) 2048 (256) 1024 (256) Operating Voltage 3.8V to 5.5V Temp. Range up to -40°C to +125 °C

Package

TQFP80 14x14 (M), TQFP64 14x14 (R),

TQFP64 10x10 (AR)

TQFP64 14x14 (R), TQFP64

10x10 (AR)

TQFP80 14x14 (M), TQFP64 14x14 (R),

TQFP64 10x10 (AR)

TQFP64 14x14 (R), TQFP64

10x10 (AR)

Rev. 5

May 2005 1/215

Table of Contents

1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2 PIN DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3 REGISTER & MEMORY MAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4 FLASH PROGRAM MEMORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.2 MAIN FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.3 STRUCTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.3.1 Read-out Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.4 ICC INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.5 ICP (IN-CIRCUIT PROGRAMMING) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4.6 IAP (IN-APPLICATION PROGRAMMING) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4.7 RELATED DOCUMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4.7.1 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

5 CENTRAL PROCESSING UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

5.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

5.2 MAIN FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

5.3 CPU REGISTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

6 SUPPLY, RESET AND CLOCK MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

6.1 PHASE LOCKED LOOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

6.2 MULTI-OSCILLATOR (MO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

6.3 RESET SEQUENCE MANAGER (RSM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

6.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

6.3.2 Asynchronous External RESET pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

6.3.3 External Power-On RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

6.3.4 Internal Low Voltage Detector (LVD) RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

6.3.5 Internal Watchdog RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

6.4 SYSTEM INTEGRITY MANAGEMENT (SI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

6.4.1 Low Voltage Detector (LVD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

6.4.2 Auxiliary Voltage Detector (AVD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

6.4.3 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

6.4.4 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

7 INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

7.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

7.2 MASKING AND PROCESSING FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

7.3 INTERRUPTS AND LOW POWER MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

7.4 CONCURRENT & NESTED MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

7.5 INTERRUPT REGISTER DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

7.6 EXTERNAL INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

7.6.1 I/O Port Interrupt Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

7.7 EXTERNAL INTERRUPT CONTROL REGISTER (EICR) . . . . . . . . . . . . . . . . . . . . . . . . . 40

8 POWER SAVING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

8.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

8.2 SLOW MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

8.3 WAIT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

215

2/215

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8.4 ACTIVE-HALT AND HALT MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

8.4.1 ACTIVE-HALT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

8.4.2 HALT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

9 I/O PORTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

9.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

9.2 FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

9.2.1 Input Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

9.2.2 Output Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

9.2.3 Alternate Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

9.3 I/O PORT IMPLEMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

9.4 LOW POWER MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

9.5 INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

9.5.1 I/O Port Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

10 ON-CHIP PERIPHERALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.1WATCHDOG TIMER (WDG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.1.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.1.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.1.4 How to Program the Watchdog Timeout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

10.1.5 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

10.1.6 Hardware Watchdog Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

10.1.7 Using Halt Mode with the WDG (WDGHALT option) . . . . . . . . . . . . . . . . . . . . . . . 56

10.1.8 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

10.1.9 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

10.2MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK AND BEEPER (MCC/RTC) . . 58

10.2.1 Programmable CPU Clock Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

10.2.2 Clock-out Capability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

10.2.3 Real Time Clock Timer (RTC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

10.2.4 Beeper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

10.2.5 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

10.2.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

10.2.7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

10.3PWM AUTO-RELOAD TIMER (ART) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

10.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

10.3.2 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

10.3.3 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

10.416-BIT TIMER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

10.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

10.4.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

10.4.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

10.4.4 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

10.4.5 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

10.4.6 Summary of Timer modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

10.4.7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

10.5SERIAL PERIPHERAL INTERFACE (SPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

10.5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

10.5.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

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10.5.3 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

10.5.4 Clock Phase and Clock Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

10.5.5 Error Flags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

10.5.6 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

10.5.7 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

10.5.8 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

10.6SERIAL COMMUNICATIONS INTERFACE (SCI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

10.6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

10.6.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

10.6.3 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

10.6.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

10.6.5 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

10.6.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

10.6.7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

10.7I2C BUS INTERFACE (I2C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

10.7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

10.7.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

10.7.3 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

10.7.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

10.7.5 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

10.7.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

10.7.7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

10.8CONTROLLER AREA NETWORK (CAN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

10.8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

10.8.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

10.8.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

10.8.4 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

10.8.5 List of CAN Cell Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

10.910-BIT A/D CONVERTER (ADC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

10.9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

10.9.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

10.9.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

10.9.4 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

10.9.5 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

10.9.6 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

11 INSTRUCTION SET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

11.1CPU ADDRESSING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

11.1.1 Inherent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

11.1.2 Immediate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

11.1.3 Direct . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

11.1.4 Indexed (No Offset, Short, Long) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

11.1.5 Indirect (Short, Long) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

11.1.6 Indirect Indexed (Short, Long) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

11.1.7 Relative mode (Direct, Indirect) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

11.2INSTRUCTION GROUPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

12 ELECTRICAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

12.1PARAMETER CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

215

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12.1.1 Minimum and Maximum values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

12.1.2 Typical values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

12.1.3 Typical curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

12.1.4 Loading capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

12.1.5 Pin input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

12.2ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

12.2.1 Voltage Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

12.2.2 Current Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

12.2.3 Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

12.3OPERATING CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

12.3.1 General Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

12.3.2 Operating Conditions with Low Voltage Detector (LVD) . . . . . . . . . . . . . . . . . . . 168

12.3.3 Auxiliary Voltage Detector (AVD) Thresholds . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

12.3.4 External Voltage Detector (EVD) Thresholds . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

12.4SUPPLY CURRENT CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

12.4.1 CURRENT CONSUMPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

12.4.2 Supply and Clock Managers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

12.4.3 On-Chip Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

12.5CLOCK AND TIMING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

12.5.1 General Timings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

12.5.2 External Clock Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

12.5.3 Crystal and Ceramic Resonator Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174

12.5.4 RC Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

12.5.5 PLL Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

12.6MEMORY CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

12.6.1 RAM and Hardware Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

12.6.2 FLASH Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

12.7EMC CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179

12.7.1 Functional EMS (Electro Magnetic Susceptibility) . . . . . . . . . . . . . . . . . . . . . . . . 179

12.7.2 Electro Magnetic Interference (EMI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180

12.7.3 Absolute Maximum Ratings (Electrical Sensitivity) . . . . . . . . . . . . . . . . . . . . . . . 181

12.8I/O PORT PIN CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

12.8.1 General Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

12.8.2 Output Driving Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

12.9CONTROL PIN CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

12.9.1 Asynchronous RESET Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

12.9.2 ICCSEL/VPP Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

12.10TIMER PERIPHERAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188

12.10.1 8-Bit PWM-ART Auto-Reload Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188

12.10.2 16-Bit Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188

12.11COMMUNICATION INTERFACE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . 189

12.11.1 SPI - Serial Peripheral Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

12.11.2 I2C - Inter IC Control Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

12.11.3 CAN - Controller Area Network Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

12.1210-BIT ADC CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

12.12.1 Analog Power Supply and Reference Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

12.12.2 General PCB Design Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

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12.12.3 ADC Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196

13 PACKAGE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

13.1PACKAGE MECHANICAL DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

13.2THERMAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

13.3SOLDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

14 ST72521 DEVICE CONFIGURATION AND ORDERING INFORMATION . . . . . . . . . . . . . . . 201

14.1FLASH OPTION BYTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

14.2DEVICE ORDERING INFORMATION AND TRANSFER OF CUSTOMER CODE . . . . . 203

14.2.1 Version-Specific Sales Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

14.3DEVELOPMENT TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206

14.3.1 Socket and Emulator Adapter Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

14.4ST7 APPLICATION NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

15 KNOWN LIMITATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

15.1ALL FLASH AND ROM DEVICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

15.1.1 External RC option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

15.1.2 Safe Connection of OSC1/OSC2 Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

15.1.3 Reset pin protection with LVD Enabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

15.1.4 Unexpected Reset Fetch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

15.1.5 Clearing active interrupts outside interrupt routine . . . . . . . . . . . . . . . . . . . . . . . 211

15.1.6 SCI Wrong Break duration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212

15.1.7 16-bit Timer PWM Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212

15.1.8 CAN Cell Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212

15.1.9 I2C Multimaster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212

15.2ALL FLASH DEVICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

15.2.1 Internal RC Oscillator with LVD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

15.2.2 I/O behaviour during ICC mode entry sequence . . . . . . . . . . . . . . . . . . . . . . . . . 213

15.2.3 Read-out protection with LVD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

16 REVISION HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

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ST72F521, ST72521B

1 INTRODUCTION

The ST72F521 and ST72521B devices are members of the ST7 microcontroller family designed for mid-range applications with a CAN bus interface (Controller Area Network).

All devices are based on a common industrystandard 8-bit core, featuring an enhan ced instruction set and are available with FLASH or ROM program memory.

Under software control, all devices can be placed in WAIT, SLOW, ACTIVE-HALT or HALT mode,

Figure 1. Device Block Diagram

8-BIT CORE

ALU

RESET

TLI

EVD

OSC1 OSC2

CONTROL

LVD

AVD

OSC

MCC/RTC/BEEP

reducing power consumption when the application is in idle or stand-by state.

The enhanced instruction set and addressing modes of the ST7 offer both power and flexibility to software developers, enabling the design of highly efficient and compact application code. In addition to standard 8-bit data management, all ST7 micr ocontrollers feature true bit manipulation, 8x8 unsigned multiplication and indirect addressing modes.

Related Documentation

AN1131: Migrating applications from ST72511/ 311/314 to ST72521/321/324

PROGRAM

MEMORY

(32K - 60K Bytes)

RAM

(1024-2048 Bytes)

WATCHDOG

ADDRESS AND DATA BUS

I2C

PORT A

PA7:0

(8-bits)

PF7:0

(8-bits)

PE7:0

(8-bits)

PD7:0

(8-bits)

AREF

SSA

PORT F

TIMER A

BEEP

PORT E

CAN

SCI

PORT D

10-BIT ADC

PORT B

PWM ART

PORT C

TIMER B

SPI

PORT G

PORT H

On some devices only, see Device Summary on page 1

PB7:0

(8-bits)

PC7:0

(8-bits)

PG7:0

(8-bits)

PH7:0

(8-bits)

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ST72F521, ST72521B

2 PIN DESCRIPTION

Figure 2. 80-Pin TQFP 14x14 Package Pinout

(HS) PE4 (HS) PE5 (HS) PE6

(HS) PE7 PWM3 / PB0 PWM2 / PB1 PWM1 / PB2 PWM0 / PB3

PG0

PG1 PG2 PG3

ARTCLK / (HS) PB4

ARTIC1 / PB5 ARTIC2 / PB6

PB7 AIN0 / PD0 AIN1 / PD1 AIN2 / PD2 AIN3 / PD3

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

PE3 / CANRX

ei2

ei3

PE2 / CANTX

PE1 / RDI

222423

PE0 / TDO

_2 V

OSC1

262827

ei1

EVD

RESET

666865

/ ICCSEL

PA7 (HS) / SCLI

PA6 (HS) / SDAI

ei0

PA5 (HS)

PA4 (HS)

SS_1

DD_1

PA3 (HS)

PA2

PA1

PA0

PC7 / SS / AIN15

PC6 / SCK /ICCCLK

PH3 PH2

PH1

PH0

PC5 / MOSI / AIN14

PC4 / MISO / ICCDATA

PC3 (HS) /ICAP1_B

PC2(HS) / ICAP2_B

PC1 / OCMP1_B / AIN13

PC0 / OCMP2_B /AIN12

VSS_0

VDD_0

PH7

727473

PH6

OSC2

PH5

PH4

TLI

8/215

PG6

PG7

SS3

DD3

SSA

PG4

AREF

AIN4/PD4

AIN6 / PD6

AIN7 / PD7

AIN5 / PD5

PG5

(HS) PF2

BEEP / (HS) PF1

MCO /AIN8 / PF0

ICAP1_A / (HS) / PF6

ICAP2_A/ AIN11 /PF5

OCMP2_A / AIN9 /PF3

OCMP1_A/AIN10 /PF4

EXTCLK_A / (HS) PF7

(HS) 20mA high sink capability eix associated external interrupt vector

PIN DESCRIPTION (Cont’d) Figure 3. 64-Pin TQFP 14x14 and 10x10 Package Pinout

ST72F521, ST72521B

(HS) PE4 (HS) PE5 (HS) PE6

(HS) PE7 PWM3 / PB0 PWM2 / PB1 PWM1 / PB2 PWM0 / PB3

ARTCLK / (HS) PB4

ARTIC1 / PB5 ARTIC2 / PB6

PB7 AIN0 / PD0 AIN1 / PD1 AIN2 / PD2 AIN3 / PD3

PE3 / CANRX

PE2 / CANTX

64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49

PE1 / RDI

PE0 / TDO

OSC1

OSC2

_2 V

TLI

/ ICCSEL

EVD

RESET

PA7 (HS) / SCLI

PA6 (HS) / SDAI

2 3 4 5 6

ei2

ei0

8 9 10

ei3

11 12 13 14 15 16

17 18 19 20 21 22 23 24 29 30 31 3225 26 27 28

SSA

AREF

AIN4 / PD4

AIN5 / PD5

AIN6 / PD6

AIN7 / PD7

ei1

SS_3

DD_3

(HS) PF2

BEEP / (HS) PF1

MCO / AIN8 / PF0

ICAP2_A / AIN11 / PF5

OCMP2_A / AIN9 / PF3

OCMP1_A / AIN10 / PF4

PA5 (HS)

PA4 (HS)

SS_1

DD_1

PA3 (HS)

PA2

PA1

PA0

PC7 / SS / AIN15

PC6 / SCK / ICCCLK

PC5 / MOSI / AIN14

PC4 / MISO / ICCDATA

PC3 (HS) / ICAP1_B

PC2 (HS) / ICAP2_B

PC1 / OCMP1_B / AIN13

PC0 / OCMP2_B / AIN12

SS_0

DD_0

ICAP1_A / (HS) PF6

EXTCLK_A / (HS) PF7

(HS) 20mA high sink capability eix associated external interrupt vector

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ST72F521, ST72521B

PIN DESCRIPTION (Cont’d)

For external pin connection guidelines, refer to See “ELECTRICAL CHARACTERISTICS” on page 165.

Legend / Abbreviations for Table 1:

Type: I = input, O = output, S = supply Input level: A = Dedicated analog input In/Output level: C = CMOS 0.3V

CT= CMOS 0.3VDD/0.7VDD with input trigger

= TTL 0.8V / 2V with Schmitt trigger

Output level: HS = 20mA high sink (on N-buffer only) Port and control configuration:

– Input: float = floating, wpu = weak pull-up, int = interrupt

– Output: OD = open drain Refer to “I/O PORTS” on page 47 for more details on the software configuration of the I/O ports. The RESET configuration of each pin is shown in bold. This configuration is valid as long as the device is

in reset state.

Table 1. Device Pin Description

/0.7V

, PP = push-pull

, ana = analog

Pin n°

TQFP80

Pin Name

TQFP64

Level Port

Type

Input

Output

float

Input Output

wpu

int

ana

function

Main

(after

reset)

Alternate function

11PE4 (HS) I/OCTHS X XXXPort E4 22PE5 (HS) I/OC 33PE6 (HS) I/OC 44PE7 (HS) I/OC 55PB0/PWM3 I/OC 66PB1/PWM2 I/OC 77PB2/PWM1 I/OC 88PB3/PWM0 I/OC

9-PG0 I/OT 10 - PG1 I/O T 11 - PG2 I/O T 12 - PG3 I/O T 13 9 PB4 (HS)/ARTCLK I/O C 14 10 PB5/ARTIC1 I/O C 15 11 PB6/ARTIC2 I/O C 16 12 PB7 I/O C 17 13 PD0 /AIN0 I/O C 18 14 PD1/AIN1 I/O C 19 15 PD2/AIN2 I/O C 20 16 PD3/AIN3 I/O C 21 - PG6 I/O T 22 - PG7 I/O T 23 17 PD4/AIN4 I/O C

HS X XXXPort E5

HS X XXXPort E6

HS X XXXPort E7

T T T T

T T T T T

T T T

X ei2 X X Port B0 PWM Output 3 X ei2 X X Port B1 PWM Output 2 X ei2 X X Port B2 PWM Output 1 X ei2 X X Port B3 PWM Output 0 X XXXPort G0 X XXXPort G1 X XXXPort G2 X XXXPort G3

HS X ei3 X X Port B4 PWM-ART External Clock

X ei3 X X Port B5 PWM-ART Input Capture 1 X ei3 X X Port B6 PWM-ART Input Capture 2 X ei3 X X Port B7 X X X X X Port D0 ADC Analog Input 0 X X X X X Port D1 ADC Analog Input 1 X X X X X Port D2 ADC Analog Input 2 X X X X X Port D3 ADC Analog Input 3 X XXXPort G6 X XXXPort G7 X X X X X Port D4 ADC Analog Input 4

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ST72F521, ST72521B

Pin n°

Pin Name

Type

TQFP80

TQFP64

24 18 PD5/AIN5 I/O C 25 19 PD6/AIN6 I/O C 26 20 PD7/AIN7 I/O C 27 21 V 28 22 V 29 23 V 30 24 V

AREF SSA DD_3 SS_3

I Analog Reference Voltage for ADC S Analog Ground Voltage S Digital Main Supply Voltage S Digital Ground Voltage

31 - PG4 I/O T 32 - PG5 I/O T

33 25 PF0/MCO/AIN8 I/O C 34 26 PF1 (HS)/BEEP I/O C

35 27 PF2 (HS) I/O C

36 28 PF3/OCMP2_A/AIN9 I/O C

37 29 PF4/OCMP1_A/AIN10 I/O C

38 30 PF5/IC AP2_A/AIN11 I/O C 39 31 PF6 (HS)/ICAP 1_A I/O C 40 32 PF7 (HS)/EXTCLK_A I/O C 41 33 V

42 34 V

DD_0 SS_0

S Digital Main Supply Voltage S Digital Ground Voltage

43 35 PC0/OCMP2_B/AIN12 I/O C

44 36 PC1/OCMP1_B/AIN13 I/O C

45 37 PC2 (HS)/ICAP2_B I/O C 46 38 PC3 (HS)/ICAP1_B I/O C

47 39 PC4/MISO/ICCDATA I/O C

48 40 PC5/MOSI/AIN14 I/O C

49 - PH0 I/O T 50 - PH1 I/O T 51 - PH2 I/O T

Level Port

Input Output

Input

Output

float

T T T

T T

X X X X X Port D5 ADC Analog Input 5 X X X X X Port D6 ADC Analog Input 6 X X X X X Port D7 ADC Analog Input 7

X XXXPort G4 X XXXPort G5

X ei1 X X X Port F0

HS X ei1 X X Port F1 Beep signal output HS X ei1 X X Port F2

wpu

int

ana

function

Main

(after

reset)

Alternate function

Main clock

CPU

)

out (f

Timer A Out-

X XXXXPort F3

put Compare 2

Timer A Out-

X XXXXPort F4

put Compare 1

X XXXXPort F5 HS X X X X Port F6 Timer A Input Capture 1 HS X XXXPort F7

Timer A Input Capture 2

Timer A External Clock Source

Timer B Out-

X XXXXPort C0

put Compare 2

Timer B Out-

X XXXXPort C1

put Compare 1

HS X X X X Port C2 Timer B Input Capture 2

HS X X X X Port C3 Timer B Input Capture 1

SPI Master In

X XXXPort C4

/ Slave Out Data

SPI Master

X XXXXPort C5

Out / Slave In Data

T T T

X XXXPort H0

X XXXPort H1

X XXXPort H2

ADC Analog Input 8

ADC Analog Input 9

ADC Analog Input 10

ADC Analog Input 11

ADC Analog Input 12

ADC Analog Input 13

ICC Data Input

ADC Analog Input 14

11/215

ST72F521, ST72521B

Pin n°

Pin Name

TQFP80

TQFP64

52 - PH3 I/O T

Level Port

Type

Input

Output

float

X XXXPort H3

Input Output

wpu

int

ana

function

Main

(after

reset)

Alternate function

SPI Serial Clock

53 41 PC6/SCK/ICCCLK I/O C

X XXXPort C6

Caution: Negative current

injection not allowed on this

pin SPI Slave

54 42 PC7/SS/AIN15 I/O C

X XXXXPort C7

Select (active

low) 55 43 PA0 I/O C 56 44 PA1 I/O C 57 45 PA2 I/O C 58 46 PA3 (HS) I/O C 59 47 V 60 48 V

DD_1 SS_1

61 49 PA4 (HS) I/O C 62 50 PA5 (HS) I/O C 63 51 PA6 (HS)/SDAI I/O C

T T T T

S Digital Main Supply Voltage S Digital Ground Voltage

T T T

64 52 PA7 (HS)/SCLI I/O CTHS X TPort A7 I

X ei0 X X Port A0 X ei0 X X Port A1 X ei0 X X Port A2

HS X ei0 X X Port A3

HS X XXXPort A4 HS X XXXPort A5 HS X TPort A6 I

C Data

C Clock

Must be tied low. In flash programming mode, this pin acts as the programming

65 53 V

/ ICCSEL I

voltage input VPP. See Section 12.9.2 for more details. High voltage must not be applied to ROM devices

66 54 RESET

I/O C

Top priority non maskable interrupt. 67 55 EVD External voltage detector 68 56 TLI I C 69 - PH4 I/O T 70 - PH5 I/O T 71 - PH6 I/O T 72 - PH7 I/O T 73 57 V

SS_2

74 58 OSC2 75 59 OSC1 76 60 V

DD_2

S Digital Ground Voltage

I/O Resonator oscillator inverter output

S Digital Main Supply Voltage 77 61 PE0/TDO I/O C 78 62 PE1/RDI I/O C 79 63 PE2/CANTX I/O C 80 64 PE3/CANRX I/O C

T T T T T

X X Top level interrupt input pin X XXXPort H4 X XXXPort H5 X XXXPort H6 X XXXPort H7

External clock input or Resonator oscillator inverter input

X X X X Port E0 SCI Transmi t Data Out X X X X Port E1 SCI Receive Data In

X Port E2 CAN Transmit Data Output

X X X X Port E3 CAN Receive Data Input

ICC Clock Output

ADC Analog Input 15

Notes:

1. In the interrupt input column, “eiX” de fines the as sociate d extern al interrup t vector . If the weak pull-up

12/215

ST72F521, ST72521B

column (wpu) is merged with the interrupt column (int), then the I/O configuration is pull-up inter rupt input, else the configuration is floating interrupt input.

2. In the open drain output column, “T” defines a true open drain I/O (P- Buffer and protection dio de to V are not implemented). See See “I/O PORTS” on pa ge 47. and Section 12.8 I/O PORT PIN CHARACTER-

ISTICS for more details.

3. OSC1 and OSC2 pins connect a crystal/ceramic resonator, or an external source to the on-chip oscillator; see Section 1 INTRODUCTION and Section 12.5 CLOCK AND TIMING CHARACTERISTICS for more details.

4. On the chip, each I/O port may have up to 8 pads. Pa ds that are not bond ed to external pins a re in input pull-up configuration after reset. The configur ation of these pads must be kept at reset st ate to avoid added current consumption.

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ST72F521, ST72521B

3 REGISTER & MEMORY MAP

As shown in Figure 4, the MCU is capable of addressing 64K bytes of memories and I/O registers.

The available memory locations consist of 128 bytes of register locations, up to 2Kbytes of RAM and up to 60Kbytes of user program memor y. The RAM space includes up to 256 bytes for the stack from 0100h to 01FFh.

The highest address bytes contain the user reset and interrupt vectors.

Figure 4. Memory Map

0000h

007Fh 0080h

087Fh 0880h

0FFFh

1000h

FFDFh FFE0h

FFFFh

HW Registers

(see Table 2)

RAM

(2048 or 1024 Bytes)

Reserved

Program Memory

(60K or 32K)

Interrupt & Reset Vectors

(see Table 7)

0080h

00FFh

0100h

01FFh

0200h

or 047Fh or 067Fh or 087Fh

IMPORTANT: Memory locations marked as “Reserved” must never be accessed. Accessing a reseved area can have unpredicta ble effects on the device.

Related Documentation

AN 985: Executing Code in ST7 RAM

Short Addressing RAM (zero page)

256 Bytes Stack

16-bit Addressing

1000h

RAM

8000h

FFFFh

60 KBytes

32 KBytes

14/215

Table 2. Hardware Register Map

ST72F521, ST72521B

Address Block

0000h 0001h

Port A

0002h 0003h

0004h

Port B

0005h 0006h

0007h

Port C

0008h 0009h

000Ah

Port D

000Bh 000Ch

000Dh

Port E

000Eh 000Fh

0010h

Port F

0011h 0012h

0013h

Port G

0014h

Label

PADR PADDR PAOR

PBDR PBDDR PBOR

PCDR PCDDR PCOR

PDDR PDDDR PDOR

PEDR PEDDR PEOR

PFDR PFDDR PFOR

PGDR

PGDDR PGOR

Port A Data Register Port A Data Direction Register Port A Option Register

Port B Data Register Port B Data Direction Register Port B Option Register

Port C Data Register Port C Data Direction Register Port C Option Register

Port D Data Register Port D Data Direction Register Port D Option Register

Port E Data Register Port E Data Direction Register Port E Option Register

Port F Data Register Port F Data Direction Register Port F Option Register

Port G Data Register Port G Data Direction Register Port G Option Register

Reset

Status

00h

00h 00h

00h

00h 00h

00h

00h 00h

00h

00h 00h

00h

00h 00h

00h

00h 00h

00h

00h 00h

Remarks

R/W R/W R/W

R/W

R/W R/W

R/W R/W R/W

0015h 0016h 0017h

0018h 0019h 001Ah 001Bh 001Ch 001Dh 001Eh

001Fh 0020h

0021h 0022h 0023h

Port H

SPI

PHDR

PHDDR PHOR

I2CCR I2CSR1 I2CSR2 I2CCCR I2COAR1 I2COAR2 I2CDR

Port H Data Register Port H Data Direction Register Port H Option Register

C Control Register

C Status Register 1

C Status Register 2

C Clock Control Register

C Own Address Register 1

C Own Address Register2

C Data Register

00h

00h 00h

00h 00h 00h 00h 00h 00h 00h

R/W R/W R/W

R/W Read Only Read Only R/W R/W R/W R/W

Reserved Area (2 Bytes)

SPIDR SPICR SPICSR

SPI Data I/O Register SPI Control Register SPI Control/Status Register

xxh 0xh 00h

R/W R/W R/W

15/215

ST72F521, ST72521B

Address Block

0024h 0025h 0026h 0027h

0028h EICR External Interrupt Control Register 00h R/W 0029h FLASH FCSR Flash Control/Status Register 00h R/W 002Ah WATCHDOG WDGCR Watchdog Control Register 7Fh R/W 002Bh SICSR System Integrity Control/Status Register 000x 000x b R/W 002Ch

002Dh 002Eh

0030h 0031h

0032h 0033h 0034h 0035h 0036h 0037h 0038h 0039h 003Ah 003Bh 003Ch 003Dh 003Eh 003Fh

ITC

MCC

TIMER A

Label

ISPR0 ISPR1 ISPR2 ISPR3

MCCSR MCCBCR

TACR2 TACR1 TACSR TAIC1HR TAIC1LR TAOC1HR TAOC1LR TACHR TACLR TAACHR TAACLR TAIC2HR TAIC2LR TAOC2HR TAOC2LR

Interrupt Software Priority Register 0 Interrupt Software Priority Register 1 Interrupt Software Priority Register 2 Interrupt Software Priority Register 3

Main Clock Control / Status Register Main Clock Controller: Beep Control Register

Reserved Area (3 Bytes)

Timer A Control Register 2 Timer A Control Register 1 Timer A Control/Status Register Timer A Input Capture 1 High Register Timer A Input Capture 1 Low Register Timer A Output Compare 1 High Register Timer A Output Compare 1 Low Register Timer A Counter High Register Timer A Counter Low Register Timer A Alternate Counter High Register Timer A Alternate Counter Low Register Timer A Input Capture 2 High Register Timer A Input Capture 2 Low Register Timer A Output Compare 2 High Register Timer A Output Compare 2 Low Register

Reset

Status

FFh FFh FFh FFh

00h 00h

xxxx x0xx b

xxh xxh 80h 00h

FFh FCh FFh FCh

xxh

80h

00h

Remarks

R/W R/W R/W R/W

R/W R/W

R/W R/W R/W Read Only Read Only R/W R/W Read Only Read Only Read Only Read Only Read Only Read Only R/W

R/W 0040h Reserved Area (1 Byte) 0041h

0042h 0043h 0044h 0045h 0046h 0047h 0048h 0049h 004Ah 004Bh 004Ch 004Dh 004Eh 004Fh

16/215

TIMER B

TBCR2 TBCR1 TBCSR TBIC1HR TBIC1LR TBOC1HR TBOC1LR TBCHR TBCLR TBACHR TBACLR TBIC2HR TBIC2LR TBOC2HR TBOC2LR

Timer B Control Register 2 Timer B Control Register 1 Timer B Control/Status Register Timer B Input Capture 1 High Register Timer B Input Capture 1 Low Register Timer B Output Compare 1 High Register Timer B Output Compare 1 Low Register Timer B Counter High Register Timer B Counter Low Register Timer B Alternate Counter High Register Timer B Alternate Counter Low Register Timer B Input Capture 2 High Register Timer B Input Capture 2 Low Register Timer B Output Compare 2 High Register Timer B Output Compare 2 Low Register

00h 00h

xxxx x0xx b

xxh xxh 80h

00h FFh FCh FFh FCh

xxh

80h

00h

R/W R/W R/W Read Only Read Only R/W R/W Read Only Read Only Read Only Read Only Read Only Read Only R/W R/W

ST72F521, ST72521B

Address Block

0050h 0051h 0052h 0053h 0054h 0055h 0056h 0057h

0058h 0059h

005Ah 005Bh 005Ch 005Dh 005Eh 005Fh 0060h

006Fh 0070h

0071h 0072h

SCI

CAN

ADC

Label

SCISR SCIDR SCIBRR SCICR1 SCICR2 SCIERPR

SCIETPR

CANISR CANICR CANCSR CANBRPR CANBTR CANPSR

ADCCSR ADCDRH ADCDRL

SCI Status Register SCI Data Register SCI Baud Rate Register SCI Control Register 1 SCI Control Register 2 SCI Extended Receive Prescaler Register Reserved area SCI Extended Transmit Prescaler Register

Reserved Area (2 Bytes)

CAN Interrupt Status Register CAN Interrupt Control Register CAN Control / Status Register CAN Baud Rate Prescaler Register CAN Bit Timing Register CAN Page Selection Register First address to Last address of CAN page x

Control/Status Register Data High Register Data Low Register

Reset

Status

C0h

xxh

00h

x000 0000b

00h

---

00h

23h

00h

Remarks

Read Only R/W R/W R/W R/W R/W

R/W

R/W R/W R/W R/W R/W R/W See CAN Description

R/W Read Only Read Only

0073h 0074h 0075h 0076h 0077h

0078h 0079h 007Ah

007Bh 007Ch 007Dh

007Eh 007Fh

PWM ART

PWMDCR3 PWMDCR2 PWMDCR1 PWMDCR0 PWMCR ARTCSR ARTCAR ARTARR ARTICCSR ARTICR1 ARTICR2

PWM AR Timer Duty Cycle Register 3 PWM AR Timer Duty Cycle Register 2 PWM AR Timer Duty Cycle Register 1 PWM AR Timer Duty Cycle Register 0 PWM AR Timer Control Register Auto-Reload Timer Control/Status Register Auto-Reload Timer Counter Access Register Auto-Reload Timer Auto-Reload Register AR Timer Input Capture Control/Status Reg. AR Timer Input Capture Register 1 AR Timer Input Capture Register 1

Reserved Area (2 Bytes)

00h

R/W R/W R/W R/W R/W R/W R/W R/W R/W Read Only Read Only

Legend: x=undefined, R/W=read/write

Notes:

1. The contents of the I/O port DR registers are readable only in output configuration. In input configuration, the values of the I/O pins are returned instead of the DR register contents.

2. The bits associated with unavailable pins must always keep their reset value.

17/215

ST72F521, ST72521B

4 FLASH PROGRAM MEMORY

4.1 Introduction

The ST7 dual voltage High Density Flash (HDFlash) is a non-volatile memory that can be electrically erased as a single block or by individual sectors and programmed on a Byte-by-Byte basis using an external V

supply.

The HDFlash devices can be programmed and erased off-board (plugged in a programming tool) or on-board using ICP (In-Circuit Programming) or IAP (In-Application Programming).

The array matrix organisation allows each sector to be erased and reprogrammed without affecting other sectors.

4.2 Main Features

■ Three Flash programming modes:

– Insertion in a programming tool. In this mode,

all sectors including option bytes can be programmed or erased.

– ICP (In-Circuit Programming). In this mode, all

sectors including option bytes can be programmed or erased without removing the device from the application board.

– IAP (In-Application Programming) In this

mode, all sectors except Sector 0, can be pr ogrammed or erased without removing the device from the application board and while the application is running.

■ ICT (In-Circuit Testing) for downloading and

executing user application test patterns in RAM

■ Read-out protection

■ Register Access Security System (RASS) to

prevent accidental programming or erasing

4.3 Structure

The Flash memory is organised in sectors and can be used for both code and data storage.

Depending on the overall Flash memory size in the microcontroller device, there are up to three user

sectors (see Table 3). Each of these sectors can be erased independently to avoid unnecessary erasing of the whole Flash memory when only a partial erasing is required.

The first two sectors have a fixed size of 4 Kbytes (see Figure 5). They are mapped in the upper par t of the ST7 addressing space so the reset and interrupt vectors are located in Sector 0 (F000hFFFFh).

Table 3. Sectors available in Flash devices

Flash Size (bytes) Available Sectors

4K Sector 0 8K Sectors 0,1

> 8K Sectors 0,1, 2

4.3.1 Read-out Protection

Read-out protection, when selected, provides a protection against Program Memory content extraction and against write access to Flash memory. Even if no protection can be considered as totally unbreakable, the feature provides a very high level of protection for a general purpose microcontroller.

In flash devices, this protection is removed by reprogramming the option. In this case, the entire program memory is first automatically erased and the device can be reprogrammed.

Read-out protection selection depends on the device type:

– In Flash devices it is enabled and removed

through the FMP_R bit in the option byte.

– In ROM devices it is enabled by mask option

specified in the Option List.

Note: In flash devices, the LVD is not supported if read-out protection is enabled.

Figure 5. Memory Map and Sector Address

4K 10K 24K 48K

1000h 3FFFh 7FFFh 9FFFh BFFFh D7FFh

DFFFh

EFFFh FFFFh

18/215

8K 16K 32K 60K

2Kbytes

8Kbytes 40 Kbytes

16 Kbytes 4 Kbytes 4 Kbytes

24 Kbytes

FLASH MEMORY SIZE

SECTOR 2

52 Kbytes

SECTOR 1 SECTOR 0

FLASH PROGRAM MEMORY (Cont’d)

ST72F521, ST72521B

4.4 ICC Interface

ICC needs a minimum of 4 and up to 6 pins to be connected to the programming tool (see Figure 6 ). These pins are:

– RESET –V

: device reset

: device power supply ground

Figure 6. Typical ICC Interface

PROGRAMMING TOOL

APPLICATION POWER SUPPLY

(See Note 3)

OPTIONAL (See Note 4)

OSC1

OSC2

ST7

Notes:

1. If the ICCCLK or ICCDATA pins are only used as outputs in the application, no signal isolation is necessary. As soon as the Programming Tool is plugged to the board, even if an ICC session is not in progress, the ICCCLK and ICCDATA pins are not available for the application. If they are used as inputs by the application, isolation such as a serial resistor has to implemented in case another device forces the signal. Refer to the Programming Tool documentation for recommended resistor values.

2. During the ICC session, the programming tool must control the RESET flicts between the programming tool and the application reset circuit if it drives more than 5mA at high level (push pull output or pull-up resistor<1K). A schottky diode can be used to isolate the ap plication RESET circuit in this case. When using a classical RC network with R>1K or a reset man-

pin. This can lead to con-

– ICCCLK: ICC output serial clock pin – ICCDATA: ICC input/output serial data pin – ICCSEL/V

: programming voltage

– OSC1(or OSCIN): main clock input for exter-

nal source (optional)

: application board power supply (option-

–V

al, see Figure 6, Note 3)

ICC CONNECTOR

975 3

10kΩ

ICCSEL/VPP

ICC Cable

1 246810

RESET

ICCCLK

HE10 CONNECTOR TYPE

ICCDATA

APPLICATION BOARD

ICC CONNECTOR

APPLICATION RESET SOURCE

See Note 2

See Note 1

APPLICATION

I/O

agement IC with open drain output and pull-up resistor>1K, no additional components are needed. In all cases the user must ensure that no ex ternal reset is generated by the application during the ICC session.

3. The use of Pin 7 of the ICC connector depends on the Programming Tool architecture. This pin must be connected when using most ST Programming Tools (it is used to monitor the application power supply). Please refer to the Programming Tool manual.

4. Pin 9 has to be connected to the OSC1 or OSCIN pin of the ST7 when the clock is not available in the application or if the selected clock option is not programmed in the option byte. ST7 devices with multi-oscillator capability need to have OSC2 grounded in this case.

19/215

ST72F521, ST72521B

FLASH PROGRAM MEMORY (Cont’d)

4.5 ICP (In-Circuit Programming)

To perform ICP the microcontroller must be switched to ICC (In-Circuit Communication) mode by an external controller or programming tool.

Depending on the ICP code downlo aded in RAM, Flash memory programming can be fully customized (number of bytes to program, program locations, or selection serial communication interface for downloading).

When using an STMicroelectronics or third-party programming tool that supports ICP and the specific microcontroller device, the user needs only to implement the ICP hardware interface on the application board (see Figure 6). For more details on the pin locations, refer to the device pinout description.

4.6 IAP (In-Application Programming)

This mode uses a BootLoader program previously stored in Sector 0 by the user (in ICP mode or by plugging the device in a programming tool).

This mode is fully controlled by user software. This allows it to be adapted to the user application, (user-defined strategy for entering programming mode, choice of communications protocol used to fetch the data to be stored, etc.). For exampl e, it is

possible to download code from the SPI, SCI, USB or CAN interface and program it in the Flash. IAP mode can be used to program any of the Flash sectors except Sector 0, which is write/erase protected to allow recovery in case errors occur during the programming operation.

4.7 Related Documentation

For details on Flash programming and ICC protocol, refer to the ST7 Flash Programming Reference Manual and to the ST7 ICC Protocol Reference Manual

4.7.1 Register Description FLASH CONTROL/STATUS REGISTER (FCSR)

Read/Write Reset Value: 0000 0000 (00h)

00000000

This register is reserved for use by Programming Tool software. It controls the Flash programming and erasing operations.

Figure 7. Flash Control/Status Register Address and Reset Value

Address

(Hex.)

0029h

Label

FCSR

Reset Value00000000

76543210

20/215

5 CENTRAL PROCESSING UNIT

ST72F521, ST72521B

5.1 INTRODUCTION

This CPU has a full 8-bit architecture and contains six internal registers allowing efficient 8-bit data manipulation.

5.2 MAIN FEATURES

■ Enable executing 63 basic instructions

■ Fast 8-bit by 8-bit multiply

■ 17 main addressing modes (with indirect

addressing mode)

■ Two 8-bit index registers

■ 16-bit stack pointer

■ Low power HALT and WAIT modes

■ Priority maskable hardware interrupts

■ Non-maskable software/ha r dwa r e in te r ru pt s

Figure 8. CPU Registers

5.3 CPU REGISTERS

The 6 CPU registers shown in Figure 8 are not present in the memory mapping and are acce ssed by specific instructions.

Accumulator (A)

The Accumulator is an 8-bit general purpose register used to hold operands and the results of the arithmetic and logic calculations and to manipulate data.

Index Registers (X and Y)

These 8-bit registers are used to create effective addresses or as temporary storage areas for data manipulation. (The Cross-Assem bler generates a precede instruction (PRE) to indicate that the following instruction refers to the Y register.)

The Y register is not affected by the interrupt automatic procedures.

Program Counter (PC)

The program counter is a 16-bit register conta ining the address of the next instruction to be executed by the CPU. It is made of two 8-bit registers PCL (Program Counter Low which is the LSB) and PCH (Program Counter High which is the MSB).

RESET VALUE = XXh

15 8

RESET VALUE = RESET VECTOR @ FFFEh-FFFFh

RESET VALUE = STACK HIGHER ADDRESS

PCH

RESET VALUE =

1C1I1HI0NZ

1X11X1XX 70

PCL

ACCUMULATOR

X INDEX REGISTER

Y INDEX REGISTER

PROGRAM COUNTER

CONDITION CODE REGISTER

STACK POINTER

X = Undefined Value

21/215

ST72F521, ST72521B

CENTRAL PROCESSING UNIT (Cont’d) Condition Code Register (CC)

Read/Write Reset Value: 111x1xxx

11I1HI0NZ

The 8-bit Condition Code register contains the interrupt masks and four flags representative of the result of the instruction just executed. This reg ister can also be handled by the PUSH and POP instructions.

These bits can be individually tested and/or controlled by specific instructions.

Arithmetic Management Bits

Bit 4 = H Half carry. This bit is set by hardware when a carry occurs be-

tween bits 3 and 4 of the ALU during an ADD or ADC instructions. It is reset by hardware during the same instructions.

0: No half carry has occurred. 1: A half carry has occurred.

This bit is tested using the JRH or JRNH instruction. The H bit is useful in BCD arithmetic subroutines.

Bit 2 = N Negative. This bit is set and cleared by hardware. I t is r epr e-

sentative of the result sign of th e last arithmetic, logical or data manipulation. It’s a copy of the re-

bit.

sult 7 0: The result of the last operation is positive or null. 1: The result of the last operation is negative

(i.e. the most significant bit is a logic 1).

This bit is accessed by the JRMI and JRPL instructions.

Bit 1 = Z Zero. This bit is set and cleared by hardware. This bit in-

dicates that the result of the last arithmetic, logical or data manipulation is zero. 0: The result of the last operation is different from

zero.

1: The result of the last operation is zero. This bit is accessed by the JREQ and JRNE test

instructions. Bit 0 = C Carry/borrow.

This bit is set and cleared by hardware and software. It indicates an overflow or an underflow has occurred during the last arithmetic operation. 0: No overflow or underflow has occurred. 1: An overflow or underflow has occurred.

This bit is driven by the SCF and RCF instructions and tested by the JRC and JRNC instructions. It is also affected by the “bit test and branch”, shift and rotate instructions.

Interrupt Management Bits

Bit 5,3 = I1, I0 Interrupt The combination of the I1 and I0 bits gives t he cur-

rent interrupt software priority.

Interrupt Software Priority I1 I0

Level 0 (main) 1 0 Level 1 0 1 Level 2 0 0 Level 3 (= interrupt disable) 1 1

These two bits are set/cleared by hardware when entering in interrupt. The loaded value is given by the corresponding bits in the interrupt software priority registers (IxSPR). They can be also set/ cleared by software with the RIM, SIM, IRET, HALT, WFI and PUSH/POP instructions.

See the interrupt management chapter for more details.

22/215

CENTRAL PROCESSING UNIT (Cont’d)

ST72F521, ST72521B

Stack Pointer (SP)

Read/Write Reset Value: 01 FFh

15 8

00000001

The least significant byte of the Stack Pointer (called S) can be directly accessed by a LD instruction.

Note: When the lower limit is exceeded, the Stack Pointer wraps around to the stack upper limit, without indicating the stack overflow. The previously stored information is then overwritten and therefore lost. The stack also wraps in case of an underflow.

SP7 SP6 SP5 SP4 SP3 SP2 SP1

SP0

The stack is used to save the return address during a subroutine call and the CPU context during an interrupt. The user may also directly manipulate the stack by means of the PUSH and POP instruc-

The Stack Pointer is a 16-bit register whic h is always pointing to the next free location in the stack. It is then decremented after d ata has been pushed onto the stack and incremented before data is popped from the stack (see Figure 9).

Since the stack is 256 bytes deep, the 8 most significant bits are forced by hardware. Following an MCU Reset, or after a Reset Stack Pointer instruction (RSP), the Stack Pointer contains its reset value (the SP7 to SP0 bits are set) which is the stack

tions. In the case of an interrupt, the PCL is st ored at the first location pointed to by the SP . Then th e other registers are stored in the next locations as shown in Figure 9.

– When an interrup t is received, the SP is decre-

mented and the context is pushed on the stack.

– On return from interrupt, the SP is incremented

and the context is popped from the stack.

A subroutine call occupies two locations and an interrupt five locations in the stack area.

higher address.

Figure 9. Stack Manipulation Example

CALL

Subroutine

Interrupt

Event

PUSH Y POP Y IRET

RET

or RSP

@ 0100h

@ 01FFh

X PCH PCL

PCH PCL

Stack Higher Address = 01FFh Stack Lower Address =

PCH PCL

0100h

A X

PCH

PCL

PCH

PCL

A X

PCH

PCL

PCH

PCL

PCH PCL

23/215

ST72F521, ST72521B

6 SUPPLY, RESET AND CLOCK MANAGEMENT

The device includes a range of utility features for securing the application in critical situations (for example in case of a power brown-out), and reducing the number of external components. An overview is shown in Figure 11.

For more details, refer to dedicated parametric section.

Main features

■ Optional PLL for multiplying the frequency by 2

(not to be used with internal RC oscillator)

■ Reset Sequence Manager (RSM)

■ Multi-Oscillator Clock Management (MO)

– 5 Crystal/Ceramic resonator oscillators – 1 Internal RC oscillator

■ System Integrity Management (SI)

– Main supply Low voltage detection (LVD) – Auxiliary Voltage detector (AVD) with interrupt

capability for monitoring the main supply or the EVD pin

Figure 11. Clock, Reset and Supply Block Diagram

6.1 PHASE LOCKED LOOP

If the clock frequency input to the PLL is in the range 2 to 4 MHz, the PLL can be used to m ult iply the frequency by two to obtain an f

OSC2

of 4 to 8 MHz. The PLL is enabled by option byte. If the PLL is disabled, then f

OSC2 = fOSC

/2.

Caution: The PLL is not recommended for applications where timing accuracy is required. See “PLL Characteristics” on page 177.

Figure 10. PLL Block Diagram

OSC

PLL x 2

/ 2

PLL OPTION BIT

OSC2

OSC1

RESET

EVD

MULTI-

OSCILLATOR

(MO)

RESET SEQUENCE

MANAGER

(RSM)

OSC

PLL

(option)

SYSTEM INTEGRITY MANAGEMENT

AVD Interrupt Request

SICSR

AVD

AVD AVD

LVD

LOW VOLTAGE

DETECTOR

AUXILIARY VOLTAGE

DETECTOR

(LVD)

(AVD)

OSC2

WDG

MAIN CLOCK

CONTROLLER

WITH REALTIME

CLOCK (MCC/RTC)

WATCHDOG

TIMER (WDG)

CPU

24/215

6.2 MULTI-OSCILLATOR (MO)

ST72F521, ST72521B

The main clock of the ST7 can be generated by three different source types coming fro m the multioscillator block:

■ an external source

■ 4 crystal or ceramic resonator oscillators

■ an internal high frequency RC oscillator

Each oscillator is optimized for a given frequency range in terms of consumption and is selectable through the option byte. The associated hardware configurations are shown in Table 4. Refer to the electrical characteristics section for more details.

Caution: The OSC1 and/or OSC2 pins must not be left unconnected. For the purposes of Failure Mode and Effect Analysis, it should be noted that if the OSC1 and/or OSC2 pins are left unconnected, the ST7 main oscillator may start and, in this configuration, could generate an f

clock frequency

OSC

in excess of the allowed maximum (>16MHz.), putting the ST7 in an unsafe/undefined state. The product behaviour must therefore be considered undefined when the OSC pins are left unconnected.

External Clock Source

In this external clock mode, a clock signal (square, sinus or triangle) with ~50% duty cycle has to drive the OSC1 pin while the OSC2 pin is tied to ground.

Crystal/Ceramic Oscillators

This family of oscillators has the advantage of producing a very accurate rate on the main clock of the ST7. The selection within a list of 4 oscillators with different frequency ranges has to be done by option byte in order to reduce consumption (refer to se ction 14.1 on page 201 for more details on the frequency ranges). In this mode of the multi-oscillator, the resonator and the load capacitors have to be placed as close as possible to the oscillator pins in order to minimize output distortion and start-up stabilization time. The loading capacitance values must be adjusted according to the selected oscillator.

These oscillators are not stopped during the RESET phase to avoid losing time in the oscillator start-up phase.

Internal RC Oscillator

This oscillator allows a low cost solution for the main clock of the ST7 using only an internal resistor and capacitor. Internal RC oscillator mode has the drawback of a lower frequency accuracy and should not be used in applications that require accurate timing.

In this mode, the two oscillator pins have to be tied to ground.

Table 4. ST7 Clock Sources

Hardware Configuration

ST7

OSC1 OSC2

External ClockCrystal/Ceramic ResonatorsInternal RC Oscillator

EXTERNAL

SOURCE

OSC1 OSC2

CAPACITORS

OSC1 OSC2

ST7

LOAD

ST7

25/215

ST72F521, ST72521B

6.3 RESET SEQUENCE MANAGER (RSM)

6.3.1 Introduction

The reset sequence manager includes three RESET sources as shown in Figure 13:

■ External RESET source pulse

■ Internal LVD RESET (Low Voltage Detection)

■ Internal WATCHDOG RESET

These sources act on the RESET

pin and it is al-

ways kept low during the delay phase. The RESET service routine vector is fixed at ad-

dresses FFFEh-FFFFh in the ST7 memory map. The basic RESET sequence consists of 3 phases

as shown in Figure 12:

■ Active Phase depending on the RESET source

■ 256 or 4096 CPU clock cycle delay (selected by

option byte)

■ RESET vector fetch

The 256 or 4096 CPU clock cycle delay allows the oscillator to stabilise and ensures that recovery has taken place from the Reset state. The shorter or longer clock cycle delay should be selected by option byte to correspond to the stabilization time of the external oscillator used in the application (see section 14.1 on page 201).

Figure 13. Reset Block Diagram

The RESET vector fetch phase duration is 2 clock cycles.

Figure 12. RESET Sequence Phases

RESET

Active Phase

INTERNAL RESET

256 or 4096 CLOCK CYCLES

6.3.2 Asynchronous External RESET

The RESET output with integrated R

pin is both an input and an open-drain

weak pull-up resistor.

FETCH

VECTOR

This pull-up has no fixed value but varies in accordance with the input voltage. It

can be pulled low by external circuitry to reset the device. See

“CONTROL PIN CHARACTERISTICS” on page 185 for more details.

A RESET signal originating from an external source must have a duration of at least t

h(RSTL)in

in order to be recognized (see Figure 14). This detection is asynchronous and therefore the MCU can enter reset state even in HALT mode.

RESET

Filter

PULSE

GENERATOR

INTERNAL RESET

WATCHDOG RESET LVD RESET

26/215

RESET SEQUENCE MANAGER (Cont’d) The RESET

pin is an asynchronous signal which plays a major role in EMS performance. In a noisy environment, it is recommended to follow the guidelines mentioned in the electrical characteristics section.

If the external RESET t

w(RSTL)out

(see short ext. Reset in Figure 14), the

signal on the RESET

pulse is shorter than

pin may be stretched. Otherwise the delay will not be applied (see long ext. Reset in Figure 14). Starting from the external RESET pulse recognition, the device RESET

pin acts as an output that is pulled low during at least t

w(RSTL)out

6.3.3 External Power-On RESET

If the LVD is disabled by option byte, to st art up the microcontroller correctly, the user must ensure by means of an external reset circuit that the reset signal is held low until V level specified for the selected f

is over the minimum

frequency.

OSC

(see “OPERATING CONDITIONS” on page 167)

Figure 14. RESET Sequences

ST72F521, ST72521B

A proper reset signal for a slow rising V can generally be provided by an external RC network connected to the RESET

pin.

6.3.4 Internal Low Voltage Detector (LVD) RESET

Two different RESET sequences caused by the internal LVD circuitry can be distinguished:

■ Power-On RESET

■ Voltage Drop RESET

The device RESET pulled low when V V

DD<VIT-

(falling edge) as shown in Figure 14.

The LVD filters spikes on V

pin acts as an output that is

DD<VIT+

(rising edge) or

larger than t

avoid parasitic resets.

6.3.5 Internal Watchdog RESET

The RESET sequence generated by a internal Watchdog counter overflow is shown in Figure 14.

Starting from the Watchdog counter under flow, the device RESET low during at least t

pin acts as an output that is pulled

w(RSTL)out

supply

g(VDD)

IT+(LVD)

IT-(LVD)

EXTERNAL RESET SOURCE

RESET PIN

WATCHDOG RESET

RUN

LVD

RESET

ACTIVE PHASE

RUN

w(RSTL)out

h(RSTL)in

SHORT EXT.

RESET

ACTIVE

PHASE

LONG EXT.

RESET

RUN RUN RUN

w(RSTL)out

h(RSTL)in

DELAY

ACTIVE PHASE

WATCHDOG UNDERFLOW

INTERNAL RESET (256 or 4096 T VECTOR FETCH

WATCHDOG

ACTIVE

PHASE

RESET

w(RSTL)out

CPU

)

27/215

ST72F521, ST72521B

6.4 SYSTEM INTEGRITY MANAGEMENT (SI)

The System Integrity Management block contains the Low Voltage Detector (LVD) and Auxiliary Voltage Detector (AVD) functions. It is managed by the SICSR register.

6.4.1 Low Voltage Detector (LVD)

The Low Voltage Detector function (LVD) generates a static reset when the V below a V

reference value. This means that it

IT-

supply voltage is

secures the power-up as well as the po wer-down keeping the ST7 in reset.

The V than the V

reference value for a voltage drop is lower

IT-

reference value for power-on in order

IT+

to avoid a parasitic reset when the MCU starts running and sinks current on the supply (hysteresis).

The LVD Reset circuitry generates a reset when

is below:

when VDD is rising

–V

IT+

when VDD is falling

–V

IT-

The LVD function is illustrated in Figure 15. The voltage threshold can be configured by option

byte to be low, medium or high.

Provided the minimum V the oscillator frequency) is above V

value (guaranteed for

, the MCU

IT-

can only be in two modes:

– under full software control – in static safe reset

In these conditions, secure operation is always ensured for the application without the need for external reset hardware.

During a Low Voltage Detector Reset, the RESET pin is held low, thus permitting the MCU to reset other devices.

Notes: The LVD allows the device to be used without any

external RESET circuitry. If the medium or low thresholds are se lected, the

detection may occur outside the specified operating voltage range. Below 3.8V, device operation is not guaranteed.

The LVD is an optional function which can be selected by option byte.

It is recommended to make sure that the V

supply voltage rises monotonously when the device is exiting from Reset, to ensure the application functions properly.

Figure 15. Low Voltage Detector vs Reset

IT+

IT-

RESET

hys

28/215

SYSTEM INTEGRITY MANAGEMENT (Cont’d)

6.4.2 Auxiliary Voltage Detector (AVD)

The Voltage Detector function (AVD) is based on an analog comparison between a V V

IT+(AVD)

reference value and the VDD main sup-

IT-(AVD)

ply or the external EVD pin voltage level (V The V than the V

reference value for falling voltage is lower

IT-

reference value for rising voltage in

IT+

and

EVD

order to avoid parasitic detection (hysteresis). The output of the AVD comparator is directly read-

able by the application software through a real time status bit (AVDF) in the SICSR register. This bit is read only.

Caution: The AVD function is active only if the LVD is enabled through the option byte.

6.4.2.1 Monitoring the V

Main Supply

This mode is selected by clearing the AVDS bit in the SICSR register.

The AVD voltage threshold value is relative to the selected LVD threshold configured by option byte (see section 14.1 on page 201).

If the AVD interrupt is enabled, an interrupt is generated when the voltage crosses the V V

IT-(AVD)

threshold (AVDF bit toggles).

Figure 16. Using the AVD to Monitor V

IT+(AVD)

(AVDS bit=0)

ST72F521, ST72521B

In the case of a drop in voltage, the AVD interrupt acts as an early warning, allowing soft ware to shut down safely before the LVD resets the microcontroller. See Figure 16.

The interrupt on the rising edge is used to inform the application that the V

If the voltage rise time t CPU cycles (depending on the reset delay selected by option byte), no AVD interrupt will be generated when V

is greater than 256 or 4096 cycles then:

If t

IT+(AVD)

is reached.

– If the AVD interrupt is enabled before the

IT+(AVD)

threshold is reached, then 2 AVD interrupts will be received: the first when the AVDIE bit is set, and the second when the threshold is reached.

– If the AVD interrupt is enabled after the V

threshold is reached then only one AVD interrupt will occur.

warning state is over.

is less than 256 or 4096

IT+(AVD)

Early Warning Interrupt

(Power has dropped, MCU not not yet in reset)

IT+(AVD)

IT-(AVD)

IT+(LVD)

IT-(LVD)

AVDF bit 0 0RESET VALUE

AVD INTERRUPT REQUEST

IF AVDIE bit = 1

LVD RESET

hyst

INTERRUPT PROCESS

VOLTAGE RISE TIME

INTERRUPT PROCESS

29/215

ST72F521, ST72521B

SYSTEM INTEGRITY MANAGEMENT (Cont’d)

6.4.2.2 Monitoring a Voltage on the EVD pin

This mode is selected by setting the AVDS bit in the SICSR register.

The AVD circuitry can generate an interrupt when the AVDIE bit of the SICSR register is set. Th is interrupt is generated on the rising and falling edges

Figure 17. Using the Voltage Detector to Monitor the EVD pin (AVDS bit=1)

EVD

IT+(EVD)

IT-(EVD)

hyst

of the comparator output. This me ans it is generated when either one of these two events occur:

–V –V

rises up to V

EVD

falls down to V

EVD

IT+(EVD)

The EVD function is illustrated in Figure 17. For more details, refer to the Electric al Charact er-

istics section.

IT-(EVD)

AVDF 0 01

AVD INTERRUPT REQUEST

IF AVDIE = 1

INTERRUPT PROCESS

30/215

SYSTEM INTEGRITY MANAGEMENT (Cont’d)

6.4.3 Low Power Modes

Mode Description

WAIT HALT The CRSR register is frozen.

No effect on SI. AVD interrupts cause the device to exit from Wait mode.

6.4.3.1 Interrupts

The AVD interrupt event generates an interrupt if the corresponding Enable Control Bit (AVDIE) is

ST72F521, ST72521B

set and the interrupt mask in the CC register is reset (RIM instruction).

Flag

Enable

Control

Bit

Interrupt Event

AVD event AVDF AVDIE Yes No

Event

Exit from Wait

Exit

from

Halt

31/215

ST72F521, ST72521B

SYSTEM INTEGRITY MANAGEMENT (Cont’d)

6.4.4 Register Description SYSTEM INTEGRITY (SI) CONTROL/STATUS REGISTER (SICSR)

Read /Write Reset Value: 000x 000x (00h)

AVD

AVDFLVD

000

WDG

ed by the LVD block. It is set by hardware (LVD reset) and cleared by software (writing zero). See WDGRF flag description for more details. When the LVD is disabled by OPTION BYTE, the LVDRF bit value is undefined.

Bits 3:1 = Reserved, must be kept cleared.

Bit 7 = AVDS Voltage Detection selection This bit is set and cleared by software. Voltage Detection is available only if the LVD is enabled by option byte. 0: Voltage detection on V

supply

1: Voltage detection on EVD pin

Bit 6 = AVDIE Voltage Detector interrupt enable This bit is set and cleared by software. It enables an interrupt to be generated when the AVDF flag changes (toggles). The pending interrupt information is automatically cleared when software enters the AVD interrupt routine. 0: AVD interrupt disabled 1: AVD interrupt enabled

Bit 5 = AVDF Voltage Detector flag This read-only bit is set and cleared by hardware. If the AVDIE bit is set, an interrup t requ est is gen erated when the AVDF bit changes value. Refer to

Figure 16 and to Section 6.4.2.1 for additional de-

tails. 0: V 1: V

DD DD

or V or V

EVD EVD

over V under V

IT+(AVD)

IT-(AVD)

threshold

Bit 4 = LVDRF LVD reset flag This bit indicates that the last Reset was generat-

Bit 0 = WDGRF Watchdog reset flag This bit indicates that the last Reset was generated by the Watchdog peripheral. It is set by hardware (watchdog reset) and cleared by software (writing zero) or an LVD Reset (to ensure a stable cleared state of the WDGRF flag when CPU starts). Combined with the LVDRF flag information, the flag description is given by the following table.

RESET Sources LVDRF WDGRF

External RESET

Watchdog 0 1

LVD 1 X

pin 0 0

Application notes

The LVDRF flag is not cleared when another RESET type occurs (external or watchdog), the LVDRF flag remains set to keep trace of the original failure. In this case, a watchdog re set c an b e de tect ed by software while an external reset can not.

CAUTION: When the LVD is not activated with the associated option byte, the WDGRF flag can not be used in the application.

32/215

7 INTERRUPTS

ST72F521, ST72521B

7.1 INTRODUCTION

The ST7 enhanced interrupt management provides the following features:

■ Hardware interrupts

■ Software interrupt (TRAP)

■ Nested or concurrent interrupt management

with flexible interrupt priority and level management:

– Up to 4 software programmable nesting levels – Up to 16 interrupt vectors fixed by hardware – 2 non maskable events: RESET, TRAP – 1 maskable Top Level event: TLI

This interrupt management is based on: – Bit 5 and bit 3 of the CPU CC register (I1:0), – Interrupt software priority registers (ISPRx), – Fixed interrupt vector addresses located at the

high addresses of the memory map (FFE0h to FFFFh) sorted by hardware priority order.

This enhanced interrupt controller guarantees full upward compatibility with the standard (not nested) ST7 interrupt controller.

7.2 MASKING AND PROCESSING FLOW

The interrupt masking is managed by the I1 and I0 bits of the CC register and the ISPRx registers which give the interrupt software priority level of

each interrupt vector (see Table 5). The processing flow is shown in Figure 18

When an interrupt request has to be serviced: – Normal processing is suspended at the end of

the current instruction execution.

– The PC, X, A and CC registers are saved onto

the stack.

– I1 and I0 bits of CC register are set according to

the corresponding values in the ISPRx registers of the serviced interrupt vector.

– The PC is then loaded with the interrupt vector of

the interrupt to service and the first instruction of the interrupt service routine is fetched (refer to “Interrupt Mapping” table for vector addresses).

The interrupt service routine should end with the IRET instruction which causes the contents of the saved registers to be recovered from the stack.

Note: As a consequence of the IRET instruction, the I1 and I0 bits will be restored from the stack and the program in the previous level will resume.

Table 5. Interrupt Software Priority Levels

Interrupt software priority Level I1 I0

Level 0 (main) Level 1 0 1 Level 2 0 0 Level 3 (= interrupt disable) 1 1

Low

High

Figure 18. Interrupt Processing Flowchart

RESET

RESTORE PC, X, A, CC

FROM STACK

PENDING

INTERRUPT

FETCH NEXT

INSTRUCTION

“IRET”

EXECUTE

INSTRUCTION

THE INTERRUPT STAYS PENDING

TRAP

Interrupt has the same or a

lower software priority

than current one

STACK PC, X, A, CC

LOAD I1:0 FROM INTERRUPT SW REG.

LOAD PC FROM INTERRUPT VECTOR

I1:0

software priority

than current one

Interrupt has a higher

33/215

ST72F521, ST72521B

INTERRUPTS (Cont’d) Servicing Pending Interrupts

As several interrupts can be pending at the same time, the interrupt to be taken into account is determined by the following two-step process:

– the highest software priority interrupt is serviced, – if several interrupts have the same software pri-

ority then the interrupt with the highest hardware priority is serviced first.

Figure 19 describes this decision process.

Figure 19. Priority Decision Process

PENDING

INTERRUPTS

Same

HIGHEST HARDWARE

PRIORITY SERVICED

SOFTWARE

PRIORITY

HIGHEST SOFTWARE

PRIORITY SERVICED

Different

When an interrupt request is not serviced immediately, it is latched and then processed when its software priority combined with the hardware priority becomes the highest one.

Note 1: The hardware priority is exclusive while the software one is not. This allows the previous process to succeed with only one interrupt. Note 2: TLI, RESET and TRAP can be considered as having the highest software p riority in th e decision process.

Different Interrupt Vector Sources

Two interrupt source types are managed by the ST7 interrupt controller: the non-maskable type (RESET, TRAP) and the maskable type (external or from internal peripherals).

Non-Maskable Sources

These sources are processed regardless of the state of the I1 and I0 bits of the CC register (see

Figure 18). After stacking the PC, X, A and CC

registers (except for RESET), the corresponding vector is loaded in the PC register and the I1 and I0 bits of the CC are set to disable interrupts (level

3). These sources allow the processor to exit HALT mode.

■ TRAP (Non Maskable Software Interrupt)

This software interrupt is serviced when the TRAP instruction is executed. It will be serviced according to the flowchart in Figure 18.

Caution: TRAP can be interrupted by a TLI.

■ RESET

The RESET source has the highest priority in the ST7. This means that the first current routine has the highest software priority (level 3) and th e highest hardware priority. See the RESET chapter for more details.

Maskable Sources

Maskable interrupt vector sources can be serviced if the corresponding interrupt is enabled and if its own interrupt software priority (in ISPRx registers) is higher than the one currently being serviced (I1 and I0 in CC register). If any of these two conditions is false, the interrupt is latched and thus remains pending.

■ TLI (Top Level Hardware Interrupt)

This hardware interrupt occurs when a specific edge is detected on the dedicated TLI pin. It will be serviced according to the flowchart in Figure 18 as a trap. Caution: A TRAP instruction must not be used in a TLI service routine.

■ External Interrupts

External interrupts allow the processor to exit from HALT low power mode. External interrup t sensitivity is software selectable through the External Interrupt Control register (EICR). External interrupt triggered on edge will be latched and the interrupt request automatically cleared upon entering the interrupt service routine. If several input pins of a group connected to the same interrupt line are selected simultaneously, these will be logically ORed.

■ Peripheral Interrupts

Usually the peripheral interrupts cause the MCU to exit from HALT mode except those mentioned in the “Interrupt Mapping” table. A peripheral interrupt occurs when a specific flag is se t in the peripheral status registers and if the corresponding enable bit is set in the peripheral control register. The general sequence for clearing an interrupt is based on an access to the status register followed by a read or write to an associated register. Note: The clearing sequence resets the internal latch. A pending interrupt (i.e. waiting for being serviced) will therefore be lost if the clear sequence is executed.

34/215

INTERRUPTS (Cont’d)

ST72F521, ST72521B

7.3 INTERRUPTS AND LOW POWER MODES

All interrupts allow the processor to exit the WAIT low power mode. On the contrary, only external and other specified interrupts allow the processor to exit from the HALT modes (see column “Exit from HALT” in “Interrupt Mapping” table). When several pending interrupts are present wh ile exiting HALT mode, the first one serviced can only be an interrupt with exit from HALT mode capability and it is selected through the same decision proc ess shown in Figure 19.

Note: If an interrupt, that is not able to Exit from HALT mode, is pending with the highest priority when exiting HALT mode, this interrupt is serviced after the first one serviced.

Figure 20. Concurrent Interrupt Management

TRAP

IT0

TRAP

IT1

RIM

IT2

IT1

IT4

IT3

IT1

HARDWARE PRIORITY

MAIN

11 / 10

7.4 CONCURRENT & NESTED MANAGEMENT

The following Figure 20 and Figure 21 show two different interrupt management modes. Th e f irst is called concurrent mode and does not allow an interrupt to be interrupted, unlike the nested mode in

Figure 21. The interrupt hardware priority is given

in this order from the lowest to the highest: MAIN, IT4, IT3, IT2, IT1, IT0, TLI. The software priority is given for each interrupt.

Warning: A stack overflow may occur without notifying the software of the failure.

SOFTWARE PRIORITY LEVEL

IT0

IT3

IT4

MAIN

3 3 3 3 3 3 3/0

11 11 11 11 11 11

USED STACK = 10 BYTES

Figure 21. Nested Interrupt Management

IT4

IT3

TRAP

IT0

HARDWARE PRIORITY

MAIN

RIM

IT2

IT1

IT4

11 / 10

IT4

IT0

IT3

IT1

SOFTWARE PRIORITY LEVEL

IT2

MAIN

I1 I0

3 3 2 1 3 3 3/0

11 11 00 01 11 11

USED STACK = 20 BYTES

35/215

ST72F521, ST72521B

INTERRUPTS (Cont’d)

7.5 INTERRUPT REGISTER DESCRIPTION

INTERRUPT SOFTWARE PRIORITY REGISTERS (ISPRX)

CPU CC REGISTER INTERRUPT BITS

Read /Write Reset Value: 111x 1010 (xAh)

11I1 H I0 NZC

Bit 5, 3 = I1, I0 Software Interrupt Priority These two bits indicate the current interrupt soft-

ware priority.

Interrupt Software Priority Level I1 I0

Level 0 (main) Level 1 0 1 Level 2 0 0 Level 3 (= interrupt disable*) 1 1

Low

High

These two bits are set/cleared by hardware when entering in interrupt. The loaded value is given by the corresponding bits in the interrupt software p riority registers (ISPRx).

They can be also set/cleared by software with the RIM, SIM, HALT, WFI, IRET and PUSH/POP instructions (see “Interrupt Dedicated Instruction Set” table).

*Note: TLI, TRAP and RESET events can interrupt a level 3 program.

Read/Write (bit 7:4 of ISPR3 are read only) Reset Value: 1111 1111 (FFh)

ISPR0 I1_3 I0_3 I1_2 I0_2 I1_1 I0_1 I1_0 I0_0

ISPR1 I1_7 I0_7 I1_6 I0_6 I1_5 I0_5 I1_4 I0_4

ISPR2 I1_11 I0_11 I1_10 I0_10 I1_9 I0_9 I1_8 I0_8

ISPR3 1 1 1 1 I1_13 I0_13 I1_12 I0_12

These four registers contain the interrupt software priority of each interrupt vector.

– Each interrupt vector (except RESET and TRAP)

has corresponding bits in these registers where its own software priority is stored. This correspondance is shown in the following table.

Vector address ISPRx bits

FFFBh-FFFAh I1_0 and I0_0 bits*

FFF9h-FFF8h I1_1 and I0_1 bits

... ...

FFE1h-FFE0h I1_13 and I0_13 bits

– Each I1_x and I0_x bit value in the ISPRx regis-

ters has the same meaning as the I1 and I0 bits in the CC register.

– Level 0 can not be written (I1_x=1, I0_x=0). In

this case, the previously stored value is kep t. (example: previous=CFh, write=64h, result=44h)

The TLI, RESET, and TRAP vectors have no software priorities. When one is serviced, the I1 and I0 bits of the CC register are both set.

*Note: Bits in the ISPRx registers which correspond to the TLI can be read and written but they are not significant in the interrupt process management.

Caution: If the I1_x and I0_x bits are modified while the interrupt x is executed the following behaviour has to be considered: If the interrupt x is still pending (new interrupt or flag not cleared) and the new software priority is higher than the previous one, the interrupt x is re-entered. Otherwise, the software priority stays unchanged up to the next interrupt request (after th e IRET of the interrupt x).

36/215

ST72F521, ST72521B

INTERRUPTS (Cont’d)

Table 6. Dedicated Interrupt Instruction Set

Instruction New Description Function/Example I1 H I0 N Z C

HALT Entering Halt mode 1 0 IRET Interrupt routine return Pop CC, A, X, PC I1 H I0 N Z C JRM Jump if I1:0=11 (level 3) I1:0=11 ? JRNM Jump if I1:0<>11 I1:0<>11 ? POP CC Pop CC from the Stack Mem => CC I1 H I0 N Z C RIM Enable interrupt (level 0 set) Load 10 in I1:0 of CC 1 0 SIM Disable interrupt (level 3 set) Load 11 in I1:0 of CC 1 1 TRAP Software trap Software NMI 1 1 WFI Wait for interrupt 1 0

Note: During the execution of an interrupt routine, the HALT, POPCC, RIM, SIM and WFI instructions change the current software priority up to the next IRET instruction or one of the previously mentioned instructions.

37/215

ST72F521, ST72521B

INTERRUPTS (Cont’d) Table 7. Interrupt Mapping

Exit

N°

0 TLI External top level interrupt EICR yes FFFAh-FFFBh 1 MCC/RTC Main clock controller time base interrupt MCCSR 2 ei0 External interrupt port A3..0 3 ei1 External interrupt port F2..0 yes FFF4h-FFF5h 4 ei2 External interrupt port B3..0 yes FFF2h-FFF3h 5 ei3 External interrupt port B7..4 yes FFF0h-FFF1h 6 CAN CAN peripheral interrupts CANISR yes FFEEh-FFEFh 7 SPI SPI peripheral interrupts SPICSR yes 8 TIMER A TIMER A peripheral interrupts TASR no FFEAh-FFEBh

9 TIMER B TIMER B peripheral interrupts TBSR no FFE8h-FFE9h 10 SCI SCI Peripheral interrupts SCISR 11 AVD Auxiliary Voltage detector interrupt SICSR no FFE4h-FFE5h 12 I2C I2C Peripheral interrupts (see periph) no FFE2h-FFE3h 13 PWM ART PWM ART interrupt ARTCSR yes

Source

Block

RESET Reset

TRAP Software interrupt no FFFCh-FFFDh

Description

Label

N/A

Priority

Order

Higher

Priority

Lower

Priority

from

HALT/

ACTIVE

HALT

yes FFFE h-FFFFh

yes FFF8h-FFF9h yes FFF6h-FFF7h

no FFE6h-FFE7h

Address

Vector

FFECh-FFEDh

FFE0h-FFE1h

Notes:

1. Exit from HALT possible when SPI is in slave mode.

2. Exit from HALT possible when PWM ART is in external clock mode.

3. In Flash devices only a RESET or MCC/RTC interrupt can be used to wake-up from Active Halt mode.

7.6 EXTERNAL INTERRUPTS

7.6.1 I/O Port Interrupt Sensitivity

The external interrupt sensitivity is controlled by the IPA, IPB and ISxx bits of the EICR register (Figure 22). This control allows to have up to 4 fully independent external interrupt source sensitivities.

Each external interrupt source can be generated on four (or five) different events on the pin:

■ Falling edge

■ Rising edge

■ Falling and rising edge

■ Falling edge and low level

■ Rising edge and high level (only for ei0 and ei 2)

To guarantee correct functionality, the sensitivity bits in the EICR register can be modified only when the I1 and I0 bits of the CC register are both set to 1 (level 3). This means that inte rrupts must be disabled before changing sensitivity.

The pending interrupts are cleared by writ ing a different value in the ISx[1:0], IPA or IPB bits of the EICR.

38/215

INTERRUPTS (Cont’d) Figure 22. External Interrupt Control bits

ST72F521, ST72521B

PORT A [3:0] INTERRUPTS

PAOR.3

PADDR.3

PA3

IPA BIT

PORT F [2:0] INTERRUPTS

PFOR.2

PFDDR.2

PF2

PORT B [3:0] INTERRUPTS

PBOR.3

PBDDR.3

PB3

IPB BIT

EICR

IS20 IS21

SENSITIVITY

CONTROL

EICR

IS20 IS21

SENSITIVITY

CONTROL

EICR

IS10 IS11

SENSITIVITY

CONTROL

PA3 PA2

PA1 PA0

PF2 PF1

PF0

PB3 PB2

PB1 PB0

ei0 INTERRUPT SOURCE

ei1 INTERRUPT SOURCE

ei2 INTERRUPT SOURCE

PORT B [7:4] INTERRUPTS

PBOR.7

PBDDR.7

PB7

EICR

IS10 IS11

SENSITIVITY

CONTROL

PB7 PB6

PB5 PB4

ei3 INTERRUPT SOURCE

39/215

ST72F521, ST72521B

7.7 EXTERNAL INTERRUPT CONTROL REGISTER (EICR)

Read /Write Reset Value: 0000 0000 (00h)

IS11 IS10 IPB IS21 IS20 IPA TLIS TLIE

Bit 7:6 = IS1[1:0] ei2 and ei3 sensitivity The interrupt sensitivity, defined using the IS1[1: 0] bits, is applied to the following external interrupts:

- ei0 (port A3..0)

IS21 IS20

00 0 1 Rising edge only Falling edge only

1 0 Falling edge only Rising edge only 1 1 Rising and falling edge

External Interrupt Sensitivity

IPA bit =0 IPA bit =1

Falling edge &

low level

- ei2 (port B3..0)

IS11 IS10

00 0 1 Rising edge only Falling edge only

1 0 Falling edge only Rising edge only 1 1 Rising and falling edge

External Interrupt Sensitivity

IPB bit =0 IPB bit =1

Falling edge &

low level

Rising edge & high level

- ei3 (port B7..4)

IS11 IS10 External Interrupt Sensitivity

0 0 Falling edge & low level 0 1 Rising edge only 1 0 Falling edge only 1 1 Rising and falling edge

- ei1 (port F2..0)

IS21 IS20 External Interrupt Sensitivity

0 0 Falling edge & low level 0 1 Rising edge only 1 0 Falling edge only 1 1 Rising and falling edge

These 2 bits can be written only when I1 and I0 of the CC register are both set to 1 (level 3).

Bit 2 = IPA Interrupt polarity for port A This bit is used to invert the sensitivity of the port A [3:0] external interrupts. It can be set and cleared by software only when I1 and I0 of the CC r egister are both set to 1 (level 3). 0: No sensitivity inversion

These 2 bits can be written only when I1 and I0 of

1: Sensitivity inversion

the CC register are both set to 1 (level 3). Bit 5 = IPB Interrupt polarity for port B

This bit is used to invert the sensitivity of the port B [3:0] external interrupts. It can be set and cleared by software only when I1 and I0 of th e CC r egi ster are both set to 1 (level 3). 0: No sensitivity inversion

Bit 1 = TLIS TLI sensitivity This bit allows to toggle the TLI edge sensitivity. It can be set and cleared by software only when TLIE bit is cleared. 0: Falling edge 1: Rising edge

1: Sensitivity inversion

Bit 0 = TLIE TLI enable

Bit 4:3 = IS2[1:0] ei0 and ei1 sensitivity The interrupt sensitivity, defined using the IS2[1: 0] bits, is applied to the following external interrupts:

This bit allows to enable or disable the TLI capability on the dedicated pin. It is set and cleared by software. 0: TLI disabled 1: TLI enabled Note: a parasitic interrupt can be generated when clearing the TLIE bit.

Rising edge & high level

40/215

INTERRUPTS (Cont’d) Table 8. Nested Interrupts Register Map and Reset Values

ST72F521, ST72521B

Address

(Hex.)

0024h

0025h

0026h

0027h

0028h

Label

ISPR0

Reset Value

ISPR1

Reset Value

ISPR2

Reset Value

ISPR3

Reset Value1111

EICR

Reset Value

76543210

ei1 ei0 MCC TLI

I1_3

I1_7

I1_11

IS11

I0_3

SPI CAN ei3 ei2

I0_7

AVD SCI TIMER B TIMER A

I0_11

IS10

I1_2

I1_6

I1_10

IPB

I0_2

I0_6

I0_10

I1_13

IS21

I1_1

I1_5

I1_9

PWMART I2C

IS20

I0_1

111

I0_5

I0_9

I0_13

IPA

I1_4

I1_8

I1_12

TLIS

I0_4

I0_8

I0_12

TLIE

41/215

ST72F521, ST72521B

8 POWER SAVING MODES

8.1 INTRODUCTION

To give a large measure of flexibility to the application in terms of power consumption, four main power saving modes are implemen ted in the ST7 (see Figure 23): SLOW, WAIT (SLOW WAIT), ACTIVE HALT and HALT.

After a RESET the normal operating mode is selected by default (RUN mode). This mode drives the device (CPU and embedded peripherals) by means of a master clock which is based on the main oscillator frequency divided or multiplied by 2

OSC2

From RUN mode, the different power saving modes may be selected by setting the relevant register bits or by calling the specific ST7 software instruction whose action depends on the oscillator status.

Figure 23. Power Saving Mode Transitions

High

RUN

SLOW

WAIT

8.2 SLOW MODE

This mode has two targets: – To reduce power consumption by decreasing the

internal clock in the device,

– To adapt the internal clock frequency (f

CPU

) to

the available supply voltage.

SLOW mode is controlled by three bits in the MCCSR register: the SMS bit which enables or disables Slow mode and two CPx bits which select the internal slow frequency (f

In this mode, the master clock frequency (f

CPU

OSC2

can be divided by 2, 4, 8 or 16. The CPU and peripherals are clocked at this lower frequency

CPU

Note: SLOW-WAIT mode is activated when ente ring the WAIT mode while the device is already in SLOW mode.

Figure 24. SLOW Mode Clock Transitions

MCCSR

CPU

OSC2

CP1:0

SMS

/2 f

OSC2

00 01

OSC2

/4 f

OSC2

)

42/215

SLOW WAIT

ACTIVE HALT

HALT

Low

POWER CONSUMPTION

NEW SLOW

FREQUENCY

REQUEST

NORMAL RUN MODE

REQUEST

POWER SAVING MODES (Cont’d)

ST72F521, ST72521B

8.3 WAIT MODE

WAIT mode places the MCU in a low power consumption mode by stopping the CPU. This power saving mode is selected by calling the ‘WFI’ instruction. All peripherals remain active. During WAIT mode, the I[1:0] bits of the CC register are forced to ‘10’, to enable all interrupts. All other registers and memory remain unchanged. The MCU remains in WAIT mode until an interrupt or RESET occurs, whereupon the Program Counter branches to the starting address of the interrupt or Reset service routine. The MCU will remain in WAIT mode until a Reset or an Interrupt occurs, causing it to wake up.

Refer to Figure 25.

Figure 25. WAIT Mode Flow-chart

OSCILLATOR

WFI INSTRUCTION

INTERRUPT

PERIPHERALS CPU I[1:0] BITS

RESET

OSCILLATOR PERIPHERALS CPU I[1:0] BITS

256 OR 4096 CPU CLOCK

CYCLE DELAY

OSCILLATOR PERIPHERALS CPU I[1:0] BITS

ON ON

OFF

ON ON ON

FETCH RESET VECTOR

OR SERVICE INTERRUPT

Note:

1. Before servicing an interrupt, the CC register is pushed on the stack. The I[1:0] bits of the CC register are set to the current software priority level of the interrupt routine and recovered when the CC register is popped.

43/215

ST72F521, ST72521B

POWER SAVING MODES (Cont’d)

8.4 ACTIVE-HALT AND HALT MODES

ACTIVE-HALT and HALT modes are the two lowest power consumption modes of the MCU. They are both entered by executing the ‘HALT’ instruction. The decision to enter either in ACTIVE-HALT or HALT mode is given by the MCC/RTC interrupt enable flag (OIE bit in MCCSR register).

MCCSR

OIE bit

Power Saving Mode entered when HALT

instruction is executed

0 HALT mode 1 ACTIVE-HALT mode

8.4.1 ACTIVE-HALT MODE

ACTIVE-HALT mode is the lowest power consumption mode of the MCU with a real time clock available. It is entered by executing the ‘HALT’ instruction when the OIE bit of the Main Clock Controller Status register (MCCSR) is set (see section

10.2 on page 58 for more details on the MCCSR

tion of an MCC/RTC interrupt or a RESET. In ROM devices, external interrupts can be used to wakeup the MCU. When exiting ACTIVE-HALT mode by means of an interrupt, no 256 or 4096 CPU cycle delay occurs. The CPU resumes operation by servicing the interrupt or by fetching the re set ve ctor which woke it up (see Figure 27).

When entering ACTIVE-HALT mode, the I[1:0] bits in the CC register are forced to ‘10b’ to enable interrupts. Therefore, if an interrupt is pending, the MCU wakes up immediately.

In ACTIVE-HALT mode, only the main oscillator and its associated counter (MCC/RTC) are running to keep a wake-up time base. All oth er peripherals are not clocked except those which get their clock supply from another clock generator (such as external or auxiliary oscillator).

The safeguard against staying locked in ACTIVEHALT mode is provided by the oscillator interrupt.

Note: As soon as the interrupt capability of one of the oscillators is selected (MCCSR.OIE bit set), entering ACTIVE-HALT mode while the Watchdog is active does not generate a RESET. This means that the device cannot spend more than a defined delay in this power saving mode.

CAUTION: When exiting ACTIVE-HALT mode following an MCC/RTC interrupt, OIE bit of MCCSR register must not be cleared before t the interrupt occurs (t

= 256 or 4096 t

DELAY

CPU

after

de-

lay depending on option byte). Otherwise, the ST7 enters HALT mode for the remaining t

DELAY

peri-

od.

Figure 26. ACTIVE-HALT Timing Overview

ACTIVE

HALTRUN RUN

HALT

INSTRUCTION

[MCCSR.OIE=1]

256 OR 4096 CPU

CYCLE DELAY

RESET

INTERRUPT

FETCH

VECTOR

Figure 27. ACTIVE-HALT Mode Flow-chart

HALT INSTRUCTION

(MCCSR.OIE=1)

INTERRUPT

OSCILLATOR PERIPHERALS CPU I[1:0] BITS

256OR4096CPUCLOCK

OSCILLATOR PERIPHERALS CPU I[1:0] BITS

FETCH RESET VECTOR

OR SERVICE INTERRUPT

RESET Y

CYCLE DELAY

OFF OFF

OFF

ON ON ON

Notes:

1. This delay occurs only if the MCU exits ACTIVEHALT mode by means of a RESET.

2. Peripheral clocked with an external clock source can still be active.

3. Before servicing an interrupt, the CC register is pushed on the stack. The I[1:0] bits of the CC register are set to the current software priority level of the interrupt routine and restored when the CC register is popped.

4. In flash devices only the MCC/RTC interrupt can exit the MCU from ACTIVE-HALT mode.

44/215

POWER SAVING MODES (Cont’d)

8.4.2 HALT MODE

The HALT mode is the lowest power consumption mode of the MCU. It is entered by ex ecuting the ‘HALT’ instruction when the OIE bit of the Main Clock Controller Status register (MCCSR) is cleared (see section 10.2 on page 58 for more details on the MCCSR register).

The MCU can exit HALT mode on reception of either a specific interrupt (see Table 7, “Interrupt Mapping,” on page 38) or a RESET. When exiting HALT mode by means of a RESET or an interrupt, the oscillator is immediately turned on and the 256 or 4096 CPU cycle delay is used to stabilize the oscillator. After the start up delay, the CPU resumes operation by servicing the interrupt or by fetching the reset vector which woke it up (see Fig-

ure 29).

When entering HALT mode, the I[1:0] bits in the CC register are forced to ‘10b’to ena ble int errupts. Therefore, if an interrupt is pending, the MCU wakes up immediately.

In HALT mode, the main oscillator is turned off causing all internal processing to be stopped, including the operation of the on-chip peripherals. All peripherals are not clocked except the ones which get their clock supply from another clock generator (such as an external or auxiliary oscillator).

The compatibility of Watchdog operation with HALT mode is configured by the “WDGHALT” option bit of the option byte. The HALT instruction when executed while the Watchdog system is enabled, can generate a Watchdog RESET (see sec-

tion 14.1 on page 201 for more details).

Figure 28. HALT Timing Overview

HALTRUN RUN

HALT

INSTRUCTION

[MCCSR.OIE=0]

256 OR 4096 CPU

CYCLE DELAY

RESET

INTERRUPT

FETCH

VECTOR

ST72F521, ST72521B

Figure 29. HALT Mode Flow-chart

HALT INSTRUCTION

(MCCSR.OIE=0)

ENABLE

WDGHALT

WATCHDOG

RESET

INTERRUPT

OSCILLATOR PERIPHERALS CPU I[1:0] BITS

256 OR 4096 CPU CLOCK

OSCILLATOR PERIPHERALS CPU I[1:0] BITS

FETCH RESET VECTOR

OR SERVICE INTERRUPT

Notes:

1. WDGHALT is an option bit. See option byte section for more details.

2. Peripheral clocked with an external clock source can still be active.

3. Only some specific interrupts can exit the MCU from HALT mode (such as external interrupt). Refer to Table 7, “Inter rupt M apping,” o n pag e 38 for more details.

4. Before servicing an interrupt, the CC register is pushed on the stack. The I[1:0] bits of the CC register are set to the current software priority level of the interrupt routine and recovered when the CC register is popped.

WATCHDOG

RESET

CYCLE

DISABLE

DELAY

OFF OFF OFF

OFF

ON ON ON

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ST72F521, ST72521B

POWER SAVING MODES (Cont’d)

8.4.2.1 Halt Mode Recommendations

– Make sure that an external event is available to

wake up the microcontroller from Halt mode.

– When using an external interrupt to wake up the

microcontroller, reinitialize the corresponding I/O as “Input Pull-up with Interrupt” before executing the HALT instruction. The main reason for this is that the I/O may be wrongly configured d ue to external interference or by an unforeseen logical condition.

– For the same reason, reinitialize the level sensi-

tiveness of each external interrupt as a precautionary measure.

– The opcode for the HALT instruction is 0x8E. To

avoid an unexpected HALT instruction due to a program counter failure, it is advised to clear all occurrences of the data value 0x8E from memo-

ry. For example, avoid defining a constant in ROM with the value 0x8E.

– As the HALT instruction clears the interrupt mask

in the CC register to allow interrupts, the user may choose to clear all pending interrupt bits before executing the HALT instruction. This avoids entering other peripheral interrupt routines after executing the external interrupt routine corresponding to the wake-up event (reset or external interrupt).

Related Documentation

AN 980: ST7 Keypad Decoding Techniques, Implementing Wake-Up on Keystroke

AN1014: How to Minimize the ST7 Power Consumption

AN1605: Using an active RC to wakeup the ST7LITE0 from power saving mode

46/215

9 I/O PORTS

ST72F521, ST72521B

9.1 INTRODUCTION

The I/O ports offer different functional mode s: – transfer of data through digital inputs and outputs

and for specific pins: – external interrupt generation – alternate signal input/output for the on-chip pe-

ripherals.

An I/O port contains up to 8 pins. Each pin can be programmed independently as digital in put (with or without interrupt generation) or digital output.

9.2 FUNCTIONAL DESCRIPTION

Each port has 2 main registers: – Data Register (DR) – Data Direction Register (DDR) and one optional register: – Option Register (OR) Each I/O pin may be programmed using the corre-

sponding register bits in the DDR and OR registers: bit X corresponding to pin X of the port. The same correspondence is used for the DR register.

The following description takes into account the OR register, (for specific ports which do not provide this register refer to the I/O Port Impleme ntation section). The generic I/O block diagram is shown in Figure 30

9.2.1 Input Modes

The input configuration is selected by clearing the corresponding DDR register bit.

In this case, reading the DR register returns the digital value applied to the external I/O pin.

Different input modes can be selected by soft ware through the OR register.

Notes:

1. Writing the DR register modifies the latch value but does not affect the pin status.

2. When switching from input to output mode, the DR register has to be written first to drive the correct level on the pin as soon as the port is configured as an output.

3. Do not use read/modify/write instructions (BSET or BRES) to modify the DR register

External interrupt function

When an I/O is configured as Input with Interrupt, an event on this I/O can generate an external inte rrupt request to the CPU.

Each pin can independently generate an interrupt request. The interrupt sensitivity is independently programmable using the sensitivity bits in the EICR register.

Each external interrupt vector is linked to a dedicated group of I/O port p ins (see pinout descr iption and interrupt section). If several input pins are selected simultaneously as interrupt sources, these are first detected according to the sensitivity b its in the EICR register and then logically ORed.

The external interrupts are hardware interrupts, which means that the request la tch (not accessible directly by the application) is automatically cleared when the corresponding interrupt vector is fetched. To clear an unwanted pending interrupt by software, the sensitivity bits in the EICR register must be modified.

9.2.2 Output Modes

The output configuration is selected by setting the corresponding DDR register bit. In this case, writing the DR register applies this digital value to the I/O pin through the latch. Then read ing the DR register returns the previously stored value.

Two different output modes can be selected by software through the OR register: Output push-pull and open-drain.

DR register value and output pin status:

DR Push-pull Open-drain

0V 1V

SS DD

Vss

Floating

9.2.3 Alternate Functions

When an on-chip peripheral is configured to use a pin, the alternate function is automatically selected. This alternate function takes pr iority over the standard I/O programming.

When the signal is coming from an on-chip peripheral, the I/O pin is automatically configured in output mode (push-pull or open drain according to the peripheral).

When the signal is going to an on-chip peripheral, the I/O pin must be configured in input mode. In this case, the pin state is also digitally readable by addressing the DR register.

Note: Input pull-up configuration can cause unexpected value at the input of the alternate p eripheral input. When an on-chip peripheral use a pin as input and output, this pin has to be configured in input floating mode.

47/215

ST72F521, ST72521B

I/O PORTS (Cont’d) Figure 30. I/O Port General Block Diagram

DATA BUS

DDR SEL

DDR

OR SEL

DR SEL

ALTERNATE OUTPUT

ALTERNATE ENABLE

If implemented

PULL-UP CONDITION

N-BUFFER

CMOS SCHMITT TRIGGER

P-BUFFER (see table below)

PULL-UP (see table below)

PAD

DIODES (see table below)

ANALOG

INPUT

EXTERNAL INTERRUPT SOURCE (eix)

Table 9. I/O Port Mode Options

Configuration Mode Pull-Up P-Buffer

Input

Output

Floating with/without Interrupt Off Pull-up with/without Interrupt On Push-pull Open Drain (logic level) Off True Open Drain NI NI NI (see note)

Legend: NI - not implemented

Off - implemented not activated On - implemented and activated

ALTERNATE

INPUT

Diodes

to V

Off

Note: The diode to V true open drain pads. A local protection between the pad and V vice against positive stress.

is implemented to protect the de-

is not implemented in the

to V

48/215

I/O PORTS (Cont’d) Table 10. I/O Port Configurations

ST72F521, ST72521B

Hardware Configuration

NOT IMPLEMENTED IN TRUE OPEN DRAIN I/O PORTS

INPUT

NOT IMPLEMENTED IN TRUE OPEN DRAIN

I/O PORTS

OPEN-DRAIN OUTPUT

PAD

PULL-UP CONDITION

INTERRUPT CONDITION

DR REGISTER ACCESS

EXTERNAL INTERRUPT SOURCE (eix)

ENABLE OUTPUT

DR REGISTER ACCESS

ALTERNATEALTERNATE

ALTERNATE INPUT

ANALOG INPUT

R/W

DATA BUS

NOT IMPLEMENTED IN TRUE OPEN DRAIN

I/O PORTS

PUSH-PULL OUTPUT

PAD

ENABLE OUTPUT

DR REGISTER ACCESS

ALTERNATEALTERNATE

R/W

DATA BUS

Notes:

1. When the I/O port is in input configuration an d the associated alternate function is enabled as an output, reading the DR register will read the alternate function output status.

2. When the I/O port is in output configurat ion and the associated alterna te function is enabled as an input , the alternate function reads the pin status given by the DR register content.

49/215

ST72F521, ST72521B

I/O PORTS (Cont’d) CAUTION: The alternate function must not be ac-

tivated as long as the pin is configured as input with interrupt, in order to avoid genera ting spurious interrupts.

Analog alternate function

When the pin is used as an ADC input, the I/O must be configured as floating input. The analog multiplexer (controlled by the ADC registers) switches the analog voltage present on the se lected pin to the common analog rail which is connected to the ADC input.

It is recommended not to change the voltage level or loading on any port pin while conversion is in progress. Furthermore it is recommended not to have clocking pins located close to a selected analog pin.

WARNING: The analog input voltage level must be within the limits stated in the absolute maximum ratings.

9.3 I/O PORT IMPLEMENTATION

The hardware implementation o n each I/O port depends on the settings in the DDR and OR registers and specific feature of the I/O port such as ADC Input or true open drain.

Switching these I/O ports from one state to another should be done in a sequence that prevents unwanted side effects. Recommended safe transitions are illustrated in Figure 31 Other transitions are potentially risky and should be avoided, since they are likely to present unwanted side-effects such as spurious interrupt generation.

Figure 31. Interrupt I/O Port State Transition s

INPUT

floating/pull-up

interrupt

INPUT

floating

(reset state)

OUTPUT

open-drain

OUTPUT push-pull

= DDR, OR

9.4 LOW POWER MODES

Mode Description

WAIT

HALT

No effect on I/O ports. External interrupts cause the device to exit from WAIT mode.

No effect on I/O ports. External interrupts cause the device to exit from HALT mode.

9.5 INTERRUPTS

The external interrupt event generates an interrupt if the corresponding configuration is selected with DDR and OR registers and the interrupt mask in the CC register is not active (RIM instruction).

Interrupt Event

External interrupt on selected external event

Event

Flag

Enable

Control

Bit

DDRx

ORx

Exit from Wait

Yes Yes

Exit

from

Halt

50/215

I/O PORTS (Cont’d)

9.5.1 I/O Port Implementation

The I/O port register configurations are summarised as follows.

Standard Ports PA5:4, PC7:0, PD7:0, PE7:34,

PE1:0, PF7:3, PG7:0, PH7:0

MODE DDR OR

floating input 0 0 pull-up input 0 1 open drain output 1 0 push-pull output 1 1

Interrupt Ports PA2:0, PB6:5, PB4, PB2:0, PF1:0 (with pull-up)

MODE DDR OR

floating input 0 0 pull-up interrupt input 0 1 open drain output 1 0 push-pull output 1 1

ST72F521, ST72521B

PA3, PB7, PB3, PF2 (without pull-up)

MODE DDR OR

floating input 0 0 floating interrupt input 0 1 open drain output 1 0 push-pull output 1 1

True Open Drain Ports PA7:6

MODE DDR

floating input 0 open drain (high sink ports) 1

Pull-up Input Port (CANTX requirement) PE2

MODE

pull-up input

Table 11. Port Configuration

Port Pin name

PA7:6 floating true open-drain

Port A

Port B

Port C PC7:0 floating pull-up open drain push-pull Port D PD7:0 floating pull-up open drain push-pull

Port E

Port F

Port G PG7:0 floating pull-up open drain push-pull

Port H PH7:0 floating pull-up open drain push-pull

* Note: when the CANTX alternate function is selected the I/O port operates in output push-pull mode.

PA5:4 floating pull-up open drain push-pull PA3 floating floating interrupt open drain push-pull PA2:0 floating pull-up interrupt open drain push-pull PB7, PB3 floating floating interrupt open drain push-pull PB6:5, PB4,

PB2:0

PE7:3, PE1:0 floating pull-up open drain push-pull PE2 pull-up input only * PF7:3 floating pull-up open drain push-pull PF2 floating floating interrupt open drain push-pull PF1:0 floating pull-up interrupt open drain push-pull

OR = 0 OR = 1 OR = 0 OR = 1

floating pull-up interrupt open drain push-pull

Input Output

51/215

ST72F521, ST72521B

I/O PORTS (Cont’d) Table 12. I/O Port Register Map and Reset Values

Address

(Hex.)

Reset Value

of all I/O port registers

0000h PADR

0002h PAOR 0003h PBDR

0005h PBOR 0006h PCDR

0008h PCOR 0009h PDDR

000Bh PDOR

000Ch PEDR

000Eh PEOR 000Fh PFDR

0011h PFOR 0012h PGDR

0014h PGOR 0015h PHDR

0017h PHOR

Label

76543210

00000000

MSB LSB0001h PADDR

MSB LSB0004h PBDDR

MSB LSB0007h PCDDR

MSB LSB000Ah PDDDR

MSB LSB000Dh PEDDR

MSB LSB0010h PFDDR

MSB LSB0013h PGDDR

MSB LSB0016h PHDDR

Related Documentation

AN 970: SPI Communication between ST7 and EEPROM

52/215

AN1045: S/W implementation of I2C bus master AN1048: Software LCD driver

10 ON-CHIP PERIPHERALS

10.1 WATCHDOG TIMER (WDG)

ST72F521, ST72521B

10.1.1 Introduction

The Watchdog timer is used to detect the occurrence of a software fault, usually generated by external interference or by unforeseen logical conditions, which causes the application program to abandon its normal sequence. The Watchdog circuit generates an MCU reset on expiry of a programmed time period, unless the program refreshes the counter’s contents before the T6 bit becomes cleared.

10.1.2 Main Features

■ Programmable free-running downcounter

■ Programmable reset

■ Reset (if watchdog activated) when the T6 bit

reaches zero

■ Optional reset on HALT instruction

(configurable by option byte)

■ Hardware Watchdog selectable by option byte

10.1.3 Functional Description

The counter value stored in the Watchdog Control register (WDGCR bits T[6:0]), is decremented every 16384 f

cycles (approx.), and the

OSC2

length of the timeout period can be programmed by the user in 64 increments.

If the watchdog is activated (the WDGA bit is set) and when the 7-bit timer (bits T[6:0]) rolls over from 40h to 3Fh (T6 becomes cleared), it initiates a reset cycle pulling low the reset pin for typically 500ns.

The application program must write in the WDGCR register at regular intervals during normal operation to prevent an MCU reset. This downcounter is free-running: it counts down even if the watchdog is disabled. The value to be stored in the WDGCR register must be between FFh and C0h:

– The WDGA bit is set (watchdog enabled) – The T6 bit is set to prevent generating an imme-

diate reset

– The T[5:0] bits contain the number of increments

which represents the time delay before the watchdog produces a reset (see Figure 33. Ap-

proximate Timeout Duration). The timing varies

between a minimum and a maximum value due to the unknown status of the prescaler when writing to the WDGCR register (see Figure 34).

Following a reset, the watchdog is disabled. Once activated it cannot be disabled, except by a reset.

The T6 bit can be used to generate a software reset (the WDGA bit is set and the T6 bit is cleared) .

If the watchdog is activated, the HALT instr uction will generate a Reset.

Figure 32. Watchdog Block Diagram

OSC2

MCC/RTC

DIV 64

12-BIT MCC

RTC COUNTER

MSB

LSB

TB[1:0] bits (MCCSR

WDGA

RESET

WATCHDOG CONTROL REGISTER (WDGCR)

6-BIT DOWNCOUNTER (CNT)

WDG PRESCALER

DIV 4

53/215

ST72F521, ST72521B

WATCHDOG TIMER (Cont’d)

10.1.4 How to Program the Watchdog Timeout

Figure 33 shows the linear relationship between

the 6-bit value to be loaded in the Watchdog Counter (CNT) and the resulting timeout duration in milliseconds. This can be used for a quick calculation without taking the timing variations into account. If

Figure 33. Approximate Timeout Duration

more precision is needed, use the formulae in Fig-

ure 34.

Caution: When writing to the WDGCR register, always write 1 in the T6 bit to avoid generating an immediate reset.

CNT Value (hex.)

1.5 65

503418 82 98 114

Watchdog timeout (ms) @ 8 MHz. f

128

OSC2

54/215

WATCHDOG TIMER (Cont’d)

ST72F521, ST72521B

Figure 34. Exact Timeout Duration (t

min

and t

max

)

WHERE:

= (LSB + 128) x 64 x t

min0

= 16384 x t

max0

OSC2

= 125ns if f

OSC2

=8 MHz

CNT = Value of T[5:0] bits in the WDGCR register (6 bits) MSB and LSB are values from the table below depending on the timebase selected by the TB[1:0] bits

in the MCCSR register

TB1 Bit

(MCCSR Reg.)

0 0 2ms 4 59 0 1 4ms 8 53 1 0 10ms 20 35 1 1 25ms 49 54

To calculate the minimum Watchdog Timeout (t

IF THEN

CNT

MSB

------------4

To calculate the maximum Watchdog Timeout (t

TB0 Bit

(MCCSR Reg.)

ELSE

mintmin0

Selected MCCSR

Timebase

mintmin0

MSB LSB

min

16384 CNT t

× 192 LSB+()64

16384 CNT

××+

osc2

max

–

4CNT

---------------- MSB

+ t

⎛⎞ ⎝⎠

××

4CNT

---------------- MSB

×+=

osc2

IF THEN

CNT

MSB

-------------

≤ t

ELSE

maxtmax0

16384 CNT t

16384 CNT

× 192 LSB+()64

××+=

osc2

–

4CNT

---------------- MSB

+ t

⎛⎞ ⎝⎠

××

4CNT

---------------- MSB

Note: In the above formulae, division results must be rounded down to the next integer value. Example:

With 2ms timeout selected in MCCSR register

Value of T[5:0] Bits in

WDGCR Register (Hex.)

00 1.496 2.048

3F 128 128.552

Min. Watchdog

Timeout (ms)

min

Max. Watchdog

Timeout (ms)

max

×+=

osc2

55/215

ST72F521, ST72521B

WATCHDOG TIMER (Cont’d)

10.1.5 Low Power Modes Mode Description

SLOW No effect on Watchdog.

WAIT No ef fect on Watchdog.

OIE bit in

MCCSR register

HALT

0 1 A reset is generated.

WDGHALT bit

in Option

Byte

No Watchdog reset is generated. The MCU enters Halt mode. The Watchdog counter is decremented once and then stops counting and is no longer able to generate a watchdog reset until the MCU receives an external interrupt or a reset.

If an external interrupt is received, the Watchdog restarts counting after 256 or 4096 CPU clocks. If a reset is generated, the Watchdog is disabled (reset state) unless Hardware Watchdog is selected by option byte. For application recommendations see Section 10.1.7 below.

No reset is generated. The MCU enters Active Halt mode. The Watchdog counter is not decremented. It stop counting. When the MCU receives an oscillator interrupt or external interrupt, the Watchdog restarts counting immediately. When the MCU receives a reset the Watchdog restarts counting after 256 or 4096 CPU clocks.

10.1.6 Hardware Watchdog Option

If Hardware Watchdog is selected by option byte, the watchdog is always active and the WDGA bit in the WDGCR is not used. Refer to the Option Byte description.

10.1.7 Using Halt Mode with the WDG

(WDGHALT option)

The following recommendation applies if Halt mode is used when the watchdog is enabled.

– Before executing the HALT instruction, refresh

the WDG counter, to avoid an unexpect ed WDG reset immediately after waking up the microcontroller.

10.1.8 Interrupts

None.

10.1.9 Register Description CONTROL REGISTER (WDGCR)

Read/Write Reset Value: 0111 1111 (7Fh)

WDGA T6 T5 T4 T3 T2 T1 T0

Bit 7 = WDGA Activation bit. This bit is set by software and only cleared by hardware after a reset. When WDGA = 1, the watchdog can generate a reset. 0: Watchdog disabled 1: Watchdog enabled

Note: This bit is not used if the hardware watchdog option is enabled by option byte.

Bit 6:0 = T[6:0] 7-bit counter (MSB to LSB). These bits contain the value of the watchdog counter. It is decremented every 16384 f

OSC2

cycles (approx.). A reset is produced when it rolls over from 40h to 3Fh (T6 becomes cleared).

56/215

Table 13. Watchdog Timer Register Map and Reset Values

ST72F521, ST72521B

Address

(Hex.)

002Ah

Label

WDGCR

Reset Value

76543210

WDGA

57/215

ST72F521, ST72521B

10.2 MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK AND BEEPER (MCC/RTC)

The Main Clock Controller consists of three different functions:

■

a programmable CPU clock prescaler

■

a clock-out signal to supply external devices

■

a real time clock timer with interrupt capability

Each function can be used independently and simultaneously.

10.2.1

Programmable CPU Clock Prescaler

The programmable CPU clock prescaler supplies the clock for the ST7 CPU and its internal peripherals. It manages SLOW power saving mode (See

Section 8.2 SLOW MODE for more details).

The prescaler selects the f

main clock frequen-

CPU

cy and is controlled by three bits in the MCCSR register: CP[1:0] and SMS.

10.2.2

Clock-out Capability

The clock-out capability is an alternate function of an I/O port pin that outputs a f

Figure 35.

Main Clock Controller (MCC/RTC) Block Diagram

clock to drive

CPU

BC1 BC0

external devices. It is controlled by the MCO bit in the MCCSR register. CAUTION: When selected, the clock out pin suspends the clock during ACTIVE-HALT mode.

10.2.3

Real Time Clock Timer (RTC)

The counter of the real time clock timer allows an interrupt to be generated based on an accurate real time clock. Four different time bases depending directly on f

are available. The whole

OSC2

functionality is controlled by four bits of the MCCSR register: TB[1:0], OIE and OIF.

When the RTC interrupt is enabled (OIE bit set), the ST7 enters ACTIVE-HALT mode when the HALT instruction is executed. See Sect ion 8.4 AC-

TIVE-HALT AND HALT MODES for more details.

10.2.4

Beeper

The beep function is controlled by the MCCBCR register. It can output t hree selectab le f reque ncies on the BEEP pin (I/O port alternate function).

OSC2

MCCBCR

DIV 64

MCO

MCCSR

DIV 2, 4, 8, 16

BEEP SIGNAL

SELECTION

12-BIT MCC RTC

COUNTER

SMSCP1 CP0 TB1 TB0 OIE OIF

WATCHDOG

TIMER

MCC/RTC INTERRUPT

CPU

BEEP

MCO

CPU CLOCK

TO CPU AND

PERIPHERALS

58/215

MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK (Cont’d)

10.2.5

Low Power Modes

Mode Description

No effect on MCC/RTC peripheral.

WAIT

ACTIVEHALT

HALT

MCC/RTC interrupt cause the device to exit from WAIT mode.

No effect on MCC/RTC counter (OIE bit is set), the registers are frozen. MCC/RTC interrupt cause the device to exit from ACTIVE-HALT mode.

MCC/RTC counter and registers are frozen. MCC/RTC operation resumes when the MCU is woken up by an interrupt with “exit from HALT” capability.

Bit 6:5 = CP[1:0] CPU clock prescaler These bits select the CPU clock prescaler which is applied in the different slow modes. Their action is conditioned by the setting of the SMS bit. These two bits are set and cleared by software

in SLOW mode CP1 CP0

CPU

OSC2

ST72F521, ST72521B

/ 2 0 0 / 4 0 1 / 8 1 0

/ 16 1 1

10.2.6

Interrupts

The MCC/RTC interrupt event generates an interrupt if the OIE bit of the MCCSR register is set and the interrupt mask in the CC register is not active (RIM instruction).

Interrupt Event

Time base overflow event

Event

Enable

Control

Flag

OIF OIE Yes No

Bit

Exit

from

Wait

Exit

from

Halt

Note: The MCC/RTC interrupt wakes up the MCU from

ACTIVE-HALT mode, not from HALT mode.

10.2.7

Register Description

MCC CONTROL/STATUS REGISTER (MCCSR)

Read /Write Reset Value: 0000 0000 (00h

)

Bit 4 = SMS Slow mode select This bit is set and cleared by software. 0: Normal mode. f 1: Slow mode. f

= f

CPU

OSC2

is given by CP1, CP0 See Section 8.2 SLOW MODE and Section 10.2

MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK AND BEEPER (MCC/RTC) for more de-

tails.

Bit 3:2 = TB[1:0] Time base control These bits select the programmable divider time

base. They are set and cleared by software.

Counter

Prescaler

16000 4ms 2ms 0 0 32000 8ms 4ms 0 1 80000 20ms 10ms 1 0

200000 50ms 25ms 1 1

OSC2

Time Base

=4MHz f

OSC2

A modification of the time base is taken into account at the end of the current period (previously

set) to avoid an unwanted time shift. This allows to use this time base as a real time clock.

MCO CP1 CP0 SMS TB1 TB0 OIE OIF

Bit 7 = MCO Main clock out selection This bit enables the MCO alternate functio n on the PF0 I/O port. It is set and cleared by software. 0: MCO alternate function disabled (I/O pin free f or

general-purpose I/O)

1: MCO alternate function enabled (f

CPU

on I/O

port)

Note: To reduce power consumption, the MCO

Bit 1 = OIE Oscillator interrupt enable This bit set and cleared by software. 0: Oscillator interrupt disabled 1: Oscillator interrupt enabled This interrupt can be used to exit from ACTIVEHALT mode. When this bit is set, calling the ST7 software HALT instruction enters the ACTIVE-HALT power saving

mode

function is not active in ACTIVE-HALT mode.

=8MHz

TB1 TB0

59/215

ST72F521, ST72521B

MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK (Cont’d)

Bit 0 = OIF Oscillator interrupt flag This bit is set by hardware and cleared by software reading the MCCSR register. It indicates when set that the main oscillator has reached the selected elapsed time (TB1:0). 0: Timeout not reached 1: Timeout reached

CAUTION: The BRES and BSET instructions must not be used on the MCCSR register to avoid unintentionally clearing the OIF bit.

MCC BEEP CONTROL REGISTER (MCCBCR)

Read/Write Reset Value: 0000 0000 (00h)

000000BC1BC0

Bit 7:2 = Reserved, must be kept cleared.

Bit 1:0 = BC[1:0] Beep control These 2 bits select the PF1 pin beep capability.

BC1 BC0 Beep mode with f

00 Off 01 ~2-KHz 10 ~1-KHz 1 1 ~500-Hz

The beep output signal is available in ACTIVEHALT mode but has to be disabled to reduce the consumption.

Table 14. Main Clock Controller Register Map and Reset Values

Address

(Hex.)

002Bh

002Ch

002Dh

Label

SICSR

Reset Value

MCCSR

Reset Value

MCCBCR

Reset Value000000

76543210

AVDS0AVDIE0AVDF0LVDRF

x000

MCO

CP1

CP0

SMS

TB1

TB0

=8MHz

OSC2

Output

Beep signal

~50% duty cycle

WDGRF

OIE

BC1

OIF

BC0

60/215

10.3 PWM AUTO-RELOAD TIMER (ART)

10.3.1 Introduction

The Pulse Width Modulated Auto-Reload Timer on-chip peripheral consists of an 8-bit auto reload counter with compare/capture capabilities and of a 7-bit prescaler clock source.

These resources allow five possible operating modes:

– Generation of up to 4 independent PWM signals – Output compare and Time base interrupt

Figure 36. PWM Auto-Reload Timer Block Diagram

ST72F521, ST72521B

– Up to two input capture functions – External even t de te cto r – Up to two external interrupt sources The three first modes can be used together with a

single counter frequency. The timer can be used to wake up the MCU from

WAIT and HALT modes.

PWMx

ARTICx

ARTCLK

PWMCR

ALTERNATE

FUNCTION

EXT

CPU

OEx

PORT

INPUT CAPTURE

MUX

ARR

CONTROL

ICIEx

OPx

POLARITY CONTROL

ICFxICSx

COUNTER

LOAD

ICCSR

OCRx

COMPARE

8-BIT COUNTER

(CAR REGISTER)

ICRx

ICx INTERRUPT

DCRx

LOAD

INPUT

EXCL CC2 CC1 CC0 TCE FCRL OIE OVF

PROGRAMMABLE

PRESCALER

ARTCSR

OVF INTERRUPT

61/215

ST72F521, ST72521B

PWM AUTO-RELOAD TIMER (Cont’d)

10.3.2 Functional Description Counter

The free running 8-bit co unter is fed by the outpu t of the prescaler, and is incremented on every rising edge of the clock signal.

It is possible to read or write the contents of the counter on the fly by reading or writing the Counter Access register (ARTCAR).

When a counter overflow occurs, the counter is automatically reloaded with the contents of the ARTARR register (the prescaler is not affected).

Counter clock and prescaler

The counter clock frequency is given by:

COUNTER

= f

INPUT

The timer counter’s input clock (f

/ 2

CC[2:0]

INPUT

) feeds the 7-bit programmable prescaler, which selects one of the 8 available taps of the prescaler, as defin e d by CC[2:0] bits in the Control/Status Register (ARTCSR). Thus the division factor of the prescaler can be set to 2

This f

INPUT

(where n = 0, 1,..7).

frequency source is selected through the EXCL bit of the ARTCSR register and can be either the f

or an external input frequency f

CPU

EXT

The clock input to the counter is enabled by the TCE (Timer Counter Enable) bit in the ARTCSR register. When TCE is reset, the counter is stopped and the prescaler and counter contents are frozen. When TCE is set, the counter runs at the rate of the selected clock source.

Counter and Prescaler Initialization

After RESET, the counter and the prescaler are cleared and f

INPUT

= f

CPU

. The counter can be initialized by: – Writing to the ARTARR register and then setting

the FCRL (Force Counter Re-Load) and the TCE (Timer Counter Enable) bits in the ARTCSR reg-

ister. – Writing to the ARTCAR counter access register, In both cases the 7-bit prescaler is also cleared,

whereupon counting will start from a known value. Direct access to the prescaler is not possible.

Output compare control

The timer compare function is based on four different comparisons with the counter (one for each PWMx output). Each comparison is made between the counter value and an output compare register (OCRx) value. This OCRx register can not be accessed directly, it is loaded from the duty cycle register (PWMDCRx) at each overflow of the counter.

This double buffering method avoids glitch generation when changing the duty cycle on the fly.

Figure 37. Output compare control

COUNTER

ARTARR=FDh

COUNTER

OCRx

PWMDCRx

PWMx

62/215

FDh FEh FFh FDh FEh FFh FDh FEh

FDh

FFh

FEh

PWM AUTO-RELOAD TIMER (Cont’d)

ST72F521, ST72521B

Independent PWM signal generation

This mode allows up to four Pulse Width Modulated signals to be generated on the PWMx output pins with minimum core processing overhead. This function is stopped during HALT mode.

Each PWMx output signal can be selected independently using the corresponding OEx bit in the PWM Control register (PWMCR). When this bit is set, the corresponding I/O pin is configured as output push-pull alternate function.

The PWM signals all have the same frequency which is controlled by the counter period and the ARTARR register value.

PWM

= f

COUNTER

/ (256 - ARTARR)

When a counter overflow occurs, the PWMx pin level is changed depending on the corresponding OPx (output polarity) bit in the PWMCR register.

Figure 38. PWM Auto-reload Timer Function

255

DUTY CYCLE

(PWMDCRx)

When the counter reaches the value contained in one of the output compare register (OCRx) the corresponding PWMx pin level is restored.

It should be noted that the reload values will also affect the value and the resolution of the duty cycle of the PWM output signal. To obtain a signal on a PWMx pin, the contents of the OCRx register must be greater than the contents of the ARTARR register.

The maximum available resolution for the PWMx duty cycle is:

Resolution = 1 / (256 - ARTARR)

Note: To get the maximum resolution (1/256), the ARTARR register must be 0. With this maximum resolution, 0% and 100% can be obtained by changing the polarity.

AUTO-RELOAD

COUNTER

(ARTARR)

000

WITH OEx=1 AND OPx=0

WITH OEx=1 AND OPx=1

PWMx OUTPUT

Figure 39. PWM Signal from 0% to 100% Duty Cycle

COUNTER

ARTARR=FDh

PWMx OUTPUT

WITH OEx=1

COUNTER

OCRx=FCh

OCRx=FDh

OCRx=FEh

AND OPx=0

OCRx=FFh

FDh FEh FFh FDh FEh FFh FDh FEh

63/215

ST72F521, ST72521B

PWM AUTO-RELOAD TIMER (Cont’d) Output compare and Time base interrupt

On overflow, the OVF flag of the ARTCSR register is set and an overflow interrupt request is gene rated if the overflow interrupt enable bit, OIE, in the ARTCSR register, is set. The OVF flag must be reset by the user software. This interrupt can be

External clock and event detector mode

Using the f auto-reload timer can be used as an external clock event detector. In this mode, the ARTARR register is used to select the n be counted before setting the OVF flag.

used as a time base in the application.

Caution: The external clock function is no t available in HALT mode. If HALT mode is used in the application, prior to executing the HALT instruction, the counter must be disabled by cleari ng the TCE bit in the ARTCSR register to avoid spurious counter increments.

Figure 40. External Event Detector Example (3 counts)

EXT=fCOUNTER

ARTARR=FDh

COUNTER

OVF

FDh FEh FFh FDh

external prescaler input clock, the

EXT

EVENT

FEh FFh FDh

= 256 - ARTARR

EVENT

number of events to

INTERRUPT

IF OIE=1

ARTCSR READ

INTERRUPT

IF OIE=1

64/215

PWM AUTO-RELOAD TIMER (Cont’d) Input capture function

This mode allows the measurement of external signal pulse widths through ARTICRx registers.

Each input capture can generate an inte rrupt independently on a selected input signal transition. This event is flagged by a set of the corresponding CFx bits of the Input Capture Control/Status register (ARTICCSR).

These input capture interrupts are enabled through the CIEx bits of the ARTICCSR register.

The active transition (falling or rising edge) is software programmable through the CSx bits of the ARTICCSR register.

The read only input capture registers (ARTICRx) are used to latch the auto-reload counter value when a transition is detected on the ARTICx pin (CFx bit set in ARTICCSR register). After fe tching the interrupt vector, the CFx flags can be read to identify the interrupt source.

Note: After a capture detection, data transfer in the ARTICRx register is inhibited until it is read (clearing the CFx bit). The timer interrupt remains pending while the CFx flag is set when the interrupt is enabled (CIEx bit set). This means, the ARTICRx register has to be read at each capture event to clear the CFx flag.

ST72F521, ST72521B

External interrupt capability

This mode allows the Input capture capabilities to be used as external interrup t sources. The interrupts are generated on the edge of the ARTICx signal.

The edge sensitivity of the external interrupts is programmable (CSx bit of ARTICCSR register) and they are independently enabled through CIEx bits of the ARTICCSR register. A fter fetching the interrupt vector, the CFx flags can be read to identify the interrupt source.

During HALT mode, the external interrupts can be used to wake up the micro (if the CIEx bit is set).

The timing resolution is given by auto-reloa d counter cycle time (1/f

COUNTER

Note: During HALT mode, if both input capture and external clock are enabled, the ARTICRx register value is not guaranteed if the input capture pin and the external clock change simultaneously.

Figure 41. Input Capture Timing Diagram

COUNTER

ARTICx PIN

CFx FLAG

ICRx REGISTER

01h

02h 03h 05h 06h 07h

xxh

04h

INTERRUPT

04h

65/215

ST72F521, ST72521B

PWM AUTO-RELOAD TIMER (Cont’d)

10.3.3 Register Description CONTROL / STATUS REGISTER (ARTCSR)

Read /Write Reset Value: 0000 0000 (00h)

0: New transition not yet reached 1: Transition reached

COUNTER ACCESS REGISTER (ARTCAR)

Read/Write Reset Value: 0000 0000 (00h)

EXCL CC2 CC1 CC0 TCE FCRL OIE OVF

Bit 7 = EXCL

External Clock

CA7 CA6 CA5 CA4 CA3 CA2 CA1 CA0

This bit is set and cleared by software. It selects the input clock for the 7-bit prescaler. 0: CPU clock. 1: External clock.

Bit 6:4 = CC[2:0] Counter Clock Control These bits are set and cleared by software. They determine the prescaler division ratio from f

COUNTER

INPUT

/ 2 / 4

/ 8 / 16 / 32 / 64

/ 128

With f

=8 MHz CC2 CC1 CC0

INPUT

8 MHz 4 MHz 2 MHz

1 MHz 500 KHz 250 KHz 125 KHz

62.5 KHz

0 0 0 0 1 1 1 1

0 0 1 1 0 0 1 1

INPUT

0 1 0 1 0 1 0 1

Bit 7:0 = CA[7:0] Counter Access Data These bits can be set and cleared either by hard-

ware or by software. The ARTCAR register is used to read or write the auto-reload counter “o n the fly” (while it is counting).

AUTO-RELOAD REGISTER (ARTARR)

Read/Write Reset Value: 0000 0000 (00h)

AR7 AR6 AR5 AR4 AR3 AR2 AR1 AR0

Bit 3 = TCE Timer Counter Enable This bit is set and cleared by software. It puts the timer in the lowest power consumption mode. 0: Counter stopped (prescaler and counter frozen). 1: Counter running.

Bit 2 = FCRL

Force Counter Re-Load

This bit is write-only and any attempt to read it will yield a logical zero. When set, it causes the contents of ARTARR register to be loaded into the counter, and the content of the prescaler register to be cleared in order to initialize the timer before starting to count.

Bit 1 = OIE

Overflow Interrupt Enable

This bit is set and cleared by software. It allows to enable/disable the interrupt which is generated when the OVF bit is set. 0: Overflow Interrupt disable. 1: Overflow Interrupt enable.

Bit 0 = OVF

Overflow Flag

This bit is set by hardware and cleared by software reading the ARTCSR register. It indicates th e transition of the counter from FFh to the ARTARR val-

Bit 7:0 =

AR[7:0]

Counter Auto-Reload Data

These bits are set and cleared by software. They are used to hold the auto-reload value which is automatically loaded in the counter when an over flow occurs. At the same time, the PWM output levels are changed according to the corresponding OPx bit in the PWMCR register.

This register has two PWM management functions:

– Adjusting the PWM frequency – Setting the PWM duty cycle resolution

PWM Frequency vs. Resolution:

ARTARR

value

0 8-bit ~0.244-KHz 31.25-KHz

[ 0..127 ] > 7-bit ~0.244-KHz 62.5-KHz [ 128..191 ] > 6-bit ~0.488-KHz 125-KHz [ 192..223 ] > 5-bit ~0.977-KHz 250-KHz [ 224..239 ] > 4-bit ~1.953-KHz 500-KHz

Resolution

PWM

Min Max

66/215

PWM AUTO-RELOAD TIMER (Cont’d)

ST72F521, ST72521B

PWM CONTROL REGISTER (PWMCR)

Read /Write Reset Value: 0000 0000 (00h)

OE3 OE2 OE1 OE0 OP3 OP2 OP1 OP0

Bit 7:4 = OE[3:0] PWM Output Enable These bits are set and cleared by software. They enable or disable the PWM output channels independently acting on the corresponding I/O pin. 0: PWM output disabled. 1: PWM output enabled.

Bit 3:0 = OP[3:0] PWM Output Polarity These bits are set and cleared by software. They independently select the polarity of the four PWM

DUTY CYCLE REGISTERS (PWMDCRx)

Read/Write Reset Value: 0000 0000 (00h)

DC7 DC6 DC5 DC4 DC3 DC2 DC1 DC0

Bit 7:0 = DC[7:0] Duty Cycle Data These bits are set and cleared by software. A PWMDCRx register is associated with the OCRx

register of each PWM channel to determine the second edge location of the PWM signal (the first edge location is common to all channels and given by the ARTARR register). These PWMDCR registers allow the duty cycle to be set independently for each PWM channel.

output signals.

PWMx output level

Counter <= OCRx Counter > OCRx

100 011

OPx

Note: When an OPx bit is modified, the PWMx out-

put signal polarity is immediately revers ed .

67/215

ST72F521, ST72521B

PWM AUTO-RELOAD TIMER (Cont’d) INPUT CAPTURE

CONTROL / STATUS REGISTER (ARTICCSR)

Read /Write

INPUT CAPTURE REGISTERS (ARTICRx)

Read only Reset Value: 0000 0000 (00h)

Reset Value: 0000 0000 (00h)

IC7 IC6 IC5 IC4 IC3 IC2 IC1 IC0

0 0 CS2 CS1 CIE2 CIE1 CF2 CF1

Bit 7:0 = IC[7:0] Input Capture Dat a

Bit 7:6 = Reserved, always read as 0.

These read only bits are set and cleared by hard-

ware. An ARTICRx register contains the 8-bit Bit 5:4 = CS[2:1] Capture Sensitivity These bits are set and cleared by software. They

auto-reload counter value transferred by the input

capture channel x event. determine the trigger ev ent polarity on the corresponding input capture channel. 0: Falling edge triggers capture on channel x. 1: Rising edge triggers capture on channel x.

Bit 3:2 = CIE[2:1] Capture Interrupt Enable These bits are set and cleared by software. They enable or disable the Input capture channel interrupts independently. 0: Input capture channel x interrupt disabled. 1: Input capture channel x interrupt enabled .

Bit 1:0 = CF[2:1] Capture Flag These bits are set by hardware and cleared by software reading the corresponding ARTICRx register. Each CFx bit indicates that an input capture x has occurred. 0: No input capture on channel x. 1: An input capture has occured on channel x.

68/215

PWM AUTO-RELOAD TIMER (Cont’d) Table 15. PWM Auto-Reload Timer Register Map and Reset Values

ST72F521, ST72521B

Address

(Hex.)

0073h

0074h

0075h

0076h

0077h

0078h

0079h

007Ah

007Bh

007Ch

007Dh

Label

PWMDCR3

Reset Value

PWMDCR2

Reset Value

PWMDCR1

Reset Value

PWMDCR0

Reset Value

PWMCR

Reset Value

ARTCSR

Reset Value

ARTCAR

Reset Value

ARTARR

Reset Value

ARTICCSR

Reset Value

ARTICR1

Reset Value

ARTICR2

Reset Value

76543210

DC7

OE3

EXCL

CA7

AR7

IC7

DC6

OE2

CC2

CA6

AR6

IC6

DC5

OE1

CC1

CA5

AR5

CS2

IC5

DC4

OE0

CC0

CA4

AR4

CS1

IC4

DC3

OP3

TCE

CA3

AR3

CIE2

IC3

DC2

OP2

FCRL

CA2

AR2

CIE1

IC2

DC1

OP1

RIE

CA1

AR1

CF2

IC1

DC0

OP0

OVF

CA0

AR0

CF1

IC0

69/215

ST72F521, ST72521B

10.4 16-BIT TIMER

10.4.1 Introduction

The timer consists of a 16-bit free-running counter driven by a programmable prescaler.

It may be used for a variety of purposes, including pulse length measurement of up to two input signals (input capture) or generation of up to two output waveforms (output compare and PWM).

Pulse lengths and waveform periods can be modulated from a few microseconds to several milliseconds using the timer prescaler and the CPU clock prescaler.

Some ST7 devices have two on-chip 16-bit timers. They are completely independent, and do not share any resources. They are synchronized after a MCU reset as long as the timer c lock frequencies are not modified.

This description covers one or two 16-bit t imers. In ST7 devices with two timers, register names are prefixed with TA (Timer A) or TB (Timer B).

10.4.2 Main Features

■ Programmable prescaler: f

■ Overflow status flag and maskable interrupt

■ External clock input (must be at least 4 times

slower than the CPU

clock speed) with the choice

divided by 2, 4 or 8.

CPU

of active edge

■ 1 or 2 Output Compare functions each with:

– 2 dedicated 16-bit registers – 2 dedicated programmable signals – 2 dedicated status flags – 1 dedicated maskable interrupt

■ 1 or 2 Input Capture functions each with:

– 2 dedicated 16-bit registers – 2 dedicated active edge selection signals – 2 dedicated status flags – 1 dedicated maskable interrupt

■ Pulse width modulation mode (PWM)

■ One pulse mode

■ Reduced Power Mode

■ 5 alternate functions on I/O ports (ICAP1, ICAP2,

OCMP1, OCMP2, EXTCLK)*

When reading an input signal on a non-bonded

pin, the value will always be ‘1’.

10.4.3 Functional Description

10.4.3.1 Counter

The main block of the Programmable Timer is a

16-bit free running upcounter and its associated

16-bit registers. The 16-bit registers are made up

of two 8-bit registers called high & low.

Counter Register (CR):

– Counter High Register (CHR) is the most sig-

nificant byte (MS Byte).

– Counter Low Register (CLR) is the least sig-

nificant byte (LS Byte).

Alternate Counter Register (ACR)

– Alternate Counter High Regi ster (ACHR) i s the

most significant byte (MS Byte).

– Alternate Counter Low Register (ACLR) is the

least significant byte (LS

Byte).

These two read-only 16-bit registers contain the

same value but with the difference that reading the

ACLR register does not clear the TOF bit (Timer

overflow flag), located in the Status register, (SR),

(see note at the end of paragraph titled 16 -bit read

sequence).

Writing in the CLR register or ACLR register resets

the free running counter to the FFFCh value.

Both counters have a reset value of FFFCh (this is

the only value which is reloaded in the 16-bit tim-

er). The reset value of both counters is also

FFFCh in One Pulse mode and PWM mode.

The timer clock depends on the clock control bits

of the CR2 register, as illustrated in Table 16 Clock

Control Bits. The value in the counter register re-

peats every 131072, 262144 or 524288 CPU clock

cycles depending on the CC[1:0] bits.

The timer frequency can be f

CPU

/2, f

CPU

/4, f

CPU

or an external frequency.

The Block Diagram is shown in Figure 42. *Note: Some timer pins may not be available ( not

bonded) in some ST7 devices. Refer to the device pin out description.

70/215

16-BIT TIMER (Cont’d) Figure 42. Timer Block Diagram

CPU

ST72F521, ST72521B

ST7 INTERNAL BUS

MCU-PERIPHERAL INTERFACE

EXTCLK

EXEDG

1/2 1/4

1/8

CC[1:0]

8 high

COUNTER

ALTERNATE

COUNTER

OVERFLOW

DETECT CIRCUIT

8 low

8-bit

buffer

high

OUTPUT

COMPARE

TIMER INTERNAL BUS

OUTPUT COMPARE

CIRCUIT

low

16 16

high

low

OUTPUT COMPARE REGISTER

88 8

high

INPUT

CAPTURE

EDGE DETECT

CIRCUIT1

EDGE DETECT

CIRCUIT2

8 8 8

low

high

low

INPUT

CAPTURE

ICAP1

ICAP2

(See note)

TIMER INTERRUPT

ICF2ICF1

OCF2OCF1 TOF

TIMD

(Control/Status Register)

CSR

(Control Register 1) CR1

LATCH1

LATCH2

OC2E

PWMOC1E

OPMFOLV2ICIE OLVL1IEDG1OLVL2FOLV1OCIETOIE

IEDG2CC0CC1

(Control Register 2) CR2

Note: If IC, OC and TO interrupt requests have separate vectors then the last OR is not present (S ee device Interrupt Vector Table)

OCMP1

OCMP2

EXEDG

71/215

ST72F521, ST72521B

16-BIT TIMER (Cont’d) 16-bit read sequence: (from either the Counter

Beginning of the sequence

Read

At t0

MS Byte

Other

instructions

Read

At t0 +∆t

LS Byte

Sequence completed

The user must read the MS Byte first , the n th e LS Byte value is buffered automatically.

This buffered value remains unchanged until the 16-bit read sequence is completed, even if the user reads the MS Byte several times.

After a complete reading sequence, if only the CLR register or ACLR register are read, they return the LS Byte of the count value at the time of the read.

Whatever the timer mode used (inpu t capture, output compare, one pulse mode or PWM mode) an overflow occurs when the counter rolls over from FFFFh to 0000h then:

– The TOF bit of the SR register is set. – A timer interrupt is generated if:

– TOIE bit of the CR1 register is set and – I bit of the CC register is cleared.

If one of these conditions is false, the interrupt remains pending to be issued as soon as they are both true.

LS Byte

is buffered

Returns the buffered

LS Byte value at t0

Clearing the overflow interrupt request is done in two steps:

1.Reading the SR register while the TOF bit is set.

2.An access (read or write) to the CLR register. Notes: The TOF bit is not cleared by accesses to

ACLR register. The advantage of accessing the ACLR register rather than the CLR register is that it allows simultaneous use of the overflow function and reading the free running counter at random times (for example, to measure elapsed time) without the risk of clearing the TOF bit erroneously.

The timer is not affected by WAIT mode. In HALT mode, the counter stops counting until the

mode is exited. Counting then resumes from the previous count (MCU awakened by an interrupt) or from the reset count (MCU awakened by a Reset) .

10.4.3.2 External Clock

The external clock (where available) is selected if CC0=1 and CC1=1 in the CR2 register.

The status of the EXEDG bit in the CR2 register determines the type of level transition on the external clock pin EXTCLK that will trigger the free running counter.

The counter is synchronized with the falling edge of the internal CPU clock.

A minimum of four falling edges of the CPU clock must occur between two consecutive active edges of the external clock; thus the external clock frequency must be less than a quarter of the CPU clock frequency.

72/215

16-BIT TIMER (Cont’d) Figure 43. Counter Timing Diagram, internal clock divided by 2

CPU CLOCK

INTERNAL RESET

TIMER CLOCK

ST72F521, ST72521B

COUNTER REGISTER

TIMER OVERFLOW FLAG (TOF)

FFFD

FFFE FFFF 0000 0001 0002 0003

Figure 44. Counter Timing Diagram, internal clock divided by 4

CPU CLOCK

INTERNAL RESET

TIMER CLOCK

COUNTER REGISTER

TIMER OVERFLOW FLAG (TOF)

FFFC FFFD 0000 0001

Figure 45. Counter Timing Diagram, internal clock divided by 8

CPU CLOCK

INTERNAL RESET

TIMER CLOCK

COUNTER REGISTER

TIMER OVERFLOW FLAG (TOF)

FFFC FFFD

0000

Note: The MCU is in reset state when the internal reset signal is high, when it is low the MCU is running.

73/215

ST72F521, ST72521B

16-BIT TIMER (Cont’d)

10.4.3.3 Input Capture

In this section, the index, i, may be 1 or 2 becau se there are 2 input capture functions in the 16-bit timer.

The two 16-bit input capture registers (IC1R and IC2R) are used to latch the value of the free running counter after a transition is detected on the ICAPi pin (see figure 5).

MS Byte LS Byte

ICiR ICiHR ICiLR

ICiR register is a read-only register. The active transition is software programmable

through the IEDGi bit of Control Registers (CRi). Timing resolution is one count of the free running

counter: (

Procedure:

To use the input capture function select the following in the CR2 register:

– Select the t imer clock (CC[1:0]) (see Table 16

Clock Control Bits).

– Select the edge of the active transition on the

ICAP2 pin with the IEDG2 bit (the ICAP2 pin must be configured as floating input or input with pull-up without interrupt if this configuration is

available). And select the following in the CR1 register: – Set the ICIE bit to generate an interrupt after an

input capture coming from either the ICAP1 pin

or the ICAP2 pin – Select the edge of the active transition on the

ICAP1 pin with the IEDG1 bit (the ICAP1pin must

be configured as floating input or input with pull-

up without interrupt if this configuration is availa-

ble).

CPU

/CC[1:0]).

When an input capture occurs: – ICFi bit is set. – The ICiR register contains the value of the free

running counter on the active transition on the ICAPi pin (see Figure 47).

– A timer interrupt is generated if the ICIE bit is set

and the I bit is cleared in the CC register . Other wise, the interrupt remains pending until both conditions become true.

Clearing the Input Capture interrupt request (i.e. clearing the ICFi bit) is done in two steps:

1. Reading the SR register while the ICFi bit is set.

2. An access (read or write) to the ICiLR register.

Notes:

1. After reading the ICiHR register, transfer of input capture data is inhibited and ICFi will never be set until the ICiLR register is also read.

2. The ICiR register contains the free running counter value which corresponds to the most recent input capture.

3. The 2 input capture functions can be used together even if the timer also uses the 2 output compare functions.

4. In One pulse Mode and PWM mode only Input Capture 2 can be used.

5. The alternate inputs (ICAP1 & ICAP2) are always directly connected to th e timer. So any transitions on these pins activates the input capture function. Moreover if one of the ICAPi pins is configured as an input and the second one as an output, an interrupt can be generated if the user toggles the output pin and if the ICIE bit is set. This can be avoided if the input capture function i is disabled by reading the ICiHR (see note

1).

6. The TOF bit can be used with interrupt generation in order to measure events that go beyond the timer range (FFFFh).

74/215

16-BIT TIMER (Cont’d) Figure 46. Input Capture Block Diagram

ST72F521, ST72521B

ICAP1

ICAP2

EDGE DETECT

CIRCUIT2

IC2R Register

16-BIT

16-BIT FREE RUNNING

COUNTER

EDGE DETECT

CIRCUIT1

IC1R Register

Figure 47. Input Capture Timing Diagram

TIMER CLOCK

ICIE

(Control Register 1) CR1

IEDG1

(Status Register) SR

ICF2ICF1 000

(Control Register 2) CR2

IEDG2

CC0

CC1

COUNTER REGISTER

ICAPi PIN

ICAPi FLAG

ICAPi REGISTER

Note: The rising edge is the active edge.

FF01 FF02 FF03

FF03

75/215

ST72F521, ST72521B

16-BIT TIMER (Cont’d)

10.4.3.4 Output Compare

In this section, the index, i, may be 1 or 2 becau se there are 2 output compare functions in the 16-bit timer.

This function can be used to control an output waveform or indicate when a period of time has elapsed.

When a match is found between the Output Compare register and the free running counter, the ou tput compare function:

– Assigns pins with a programmable value if the

OCiE bit is set – Sets a flag in the status register – Generates an interrupt if enabled

Two 16-bit registers Output Compare Register 1 (OC1R) and Output Compare Register 2 (OC2R) contain the value to be compared to the counter register each timer clock c ycle.

MS Byte LS Byte

OCiROCiHR OCiLR

These registers are readable and writable and are not affected by the timer hardware . A reset event changes the OC

Timing resolution is one count of the free running counter: (

Procedure:

To use the output compare function, select the following in the CR2 register:

– Set the OCiE bit if an output is needed then the

OCMPi pin is dedicated to the output compare i signal.

– Select the t imer clock (CC[1:0]) (see Table 16

Clock Control Bits).

And select the following in the CR1 register: – Select the OLVLi bit to applied to the OCMPi pins

after the match occurs. – Set the OCIE bit to generate an interrupt if it is

needed. When a match is found between OCRi register

and CR register: – OCFi bit is set.

iR value to 8000h.

CC[1:0]

CPU/

– The OCMPi pin takes OLVLi bit value (OCMPi

pin latch is forced low during reset).

– A timer interrupt is generated if the OCIE bit is

set in the CR1 register and the I bit is cleared in the CC register (CC).

The OC

iR register value required for a specific ti m-

ing application can be calculated using the following formula:

∆t * f

∆ OCiR =

CPU

PRESC

Where:

∆t = Output compare period (in seconds)

= CPU clock frequency (in hertz)

CPU

PRESC

= Timer prescaler factor (2, 4 or 8 de-

pending on CC[1:0] bits, see Table 16

Clock Control Bits)

If the timer clock is an external clock, the fo rmula is:

∆ OCiR = ∆t

* fEXT

Where:

∆t = Output compare period (in seconds)

= External timer clock frequency (in hertz)

EXT

Clearing the output compare interru pt re qu est ( i. e. clearing the OCFi bit) is done by:

1. Reading the SR register while the OCFi bit is set.

2. An access (read or write) to the OCiLR regi ster .

The following procedure is recommended to prevent the OCFi bit from being set between the time it is read and the write to the OC

– Write to the OCiHR register (further compares

are inhibited).

– Read the SR register (first step of the clearance

of the OCFi bit, which may be already set).

– Write to the OCiLR register (enables the output

compare function and clears the OCFi bit).

iR register:

76/215

16-BIT TIMER (Cont’d) Notes:

1. After a processor write cycle to the OCiHR reg- ister, the output compare function is inhibited until the OCiLR register is also written.

2. If the OCiE bit is not set, the OCMPi pin is a general I/O port and the OLVLi bit will not appear when a match is found but an interrupt could be generated if the OCIE bit is set.

3. When the timer clock is f

/2, OCFi and

CPU

OCMPi are set while the counter value equals the OCiR register value (see Figure 49 on page

78). This behaviour is the same in OPM or

PWM mode. When the timer clock is f

CPU

/4, f

CPU

/8 or in external clock mode, OCFi and OCMPi are set while the counter value equals the OC iR register value plus 1 (see Figure 50 on page 78).

4. The output compare functions ca n be used both for generating external events on the OCMPi pins even if the input capture mode is also used.

5. The value in the 16-bit OC

iR register and the

OLVi bit should be changed after each successful comparison in order to control an output waveform or establish a new elapsed timeout.

ST72F521, ST72521B

Forced Compare Output capability

When the FOLVi bit is set by software, the OLVLi bit is copied to the OCMPi pin. The OLVi bit has to be toggled in order to toggle the OCMPi pin when it is enabled (OCiE bit=1). The OCFi bit is then not set by hardware, and thus no interrupt request is generated.

The FOLVLi bits have no effect in both one pulse mode and PWM mode.

Figure 48. Output Compare Block Diagram

16 BIT FREE RUNNING

COUNTER

16-bit

OUTPUT COMPARE

CIRCUIT

16-bit

OC1R Register

16-bit

OC2R Register

OC1E CC0CC1

OC2E

(Control Register 2) CR2

(Control Register 1) CR1

FOLV1

FOLV2

(Status Register) SR

OLVL1OLVL2OCIE

000OCF2OCF1

Latch

OCMP1

OCMP2

77/215

ST72F521, ST72521B

16-BIT TIMER (Cont’d) Figure 49. Output Compare Timing Diagram, f

INTERNAL CPU CLOCK

TIMER CLOCK

TIMER

CPU

COUNTER REGISTER

OUTPUT COMPARE REGISTER i (OCRi)

OUTPUT COMPARE FLAG i (OCFi)

OCMPi PIN (OLVLi=1)

Figure 50. Output Compare Timing Diagram, f

INTERNAL CPU CLOCK

TIMER CLOCK

COUNTER REGISTER

OUTPUT COMPARE REGISTER i (OCRi)

COMPARE REGISTER i LATCH

OUTPUT COMPARE FLAG i (OCFi)

OCMPi PIN (OLVLi=1)

2ED0 2ED1 2ED2

TIMER

CPU

2ED0 2ED1 2ED2

2ED3

2ED42ECF

78/215

16-BIT TIMER (Cont’d)

10.4.3.5 One Pulse Mode

One Pulse mode enables the generation of a pulse when an external event occurs. This mode is selected via the OPM bit in the CR2 register.

The one pulse mode uses the Input Capture1 function and the Output Compare1 function.

Procedure:

To use one pulse mode:

1. Load the OC1R register with the value corresponding to the length of the pulse (see the formula in the opposite column).

2. Select the following in the CR1 register: – Using the OLVL1 bit, select the level to be ap-

plied to the OCMP1 pin after the pulse.

– Using the OLVL2 bit, select the level to be ap-

plied to the OCMP1 pin during the pulse.

– Select the edge of the active transition on the

ICAP1 pin with the IEDG1 bit (the ICAP1 pi n must be configured as floating input).

3. Select the following in the CR2 register: – Set the OC1E bit, the OCMP1 pin is then ded-

icated to the Output Compare 1 function. – Set the OPM bit. – Select the timer clock CC[1:0] (see Table 16

Clock Control Bits).

ST72F521, ST72521B

Clearing the Input Capture interrupt request (i.e. clearing the ICFi bit) is done in two steps:

1. Reading the SR register while the ICFi bit is set.

2. An access (read or write) to the ICiLR register. The OC1R register value required for a specific

timing application can be calculated using the following formula:

OCiR Value =

CPU

PRESC

Where: t = Pulse period (in seconds)

= CPU clock frequency (in hertz)

CPU

PRESC

= Timer prescaler factor (2, 4 or 8 depend-

ing on the CC[1:0] bits, see Table 16

Clock Control Bits)

If the timer clock is an external clock the formula is:

OCiR = t

* fEXT

-5

Where: t = Pulse period (in seconds)

= External timer clock frequency (in hertz)

EXT

When the value of the counter is equal to the value of the contents of the OC 1R register, the OLVL1 bit is output on the OCMP1 pin, (See Figure 51).

- 5

One pulse mode cycle

When

event occurs

on ICAP1

ICR1 = Counter

OCMP1 = OLVL2

Counter is reset

to FFFCh

ICF1 bit is set

When

Counter = OC1R

OCMP1 = OLVL1

Then, on a valid event on the ICAP1 pin, the co unter is initialized to FFFCh and OLVL2 bit is loaded on the OCMP1 pin, the ICF1 bit is set and the value FFFDh is loaded in the IC1R register.

Because the ICF1 bit is set when an active edge occurs, an interrupt can be generated if the ICIE bit is set.

Notes:

1. The OCF1 bit cannot be set by hard wa re in one pulse mode but the OCF2 bit can generate an Output Compare interrupt.

2. When the Pulse Width Modulation (PWM) and One Pulse Mode (OPM) bits are both set, the PWM mode is the only active one.

3. If OLVL1=OLVL2 a continuous signal will be seen on the OCMP1 pin.

4. The ICAP1 pin can not be used to pe rform input capture. The ICAP2 pin can be used to perform input capture (ICF2 can be set and IC2R ca n be loaded) but the user must take care that the counter is reset each time a valid edge occurs on the ICAP1 pin and ICF1 can also generates interrupt if ICIE is set.

5. When one pulse mode is used OC1R is dedicated to this mode. Nevertheless OC2R and OCF2 can be used to indicate a period of time has been elapsed but cannot generate an output waveform because the level OLVL2 is dedicated to the one pulse mode.

79/215

ST72F521, ST72521B

16-BIT TIMER (Cont’d) Figure 51. One Pulse Mode Timing Example

IC1R

COUNTER

ICAP1

OCMP1

01F8

FFFC

FFFD FFFE 2ED0

OLVL2

01F8

2ED1

2ED2

2ED3

FFFC FFFD

OLVL2OLVL1

compare1

Note: IEDG1=1, OC1R=2ED0h, OLVL1=0, OLVL2=1

Figure 52. Pulse Width Modulation Mode Timing Example with 2 Output Compare Functions

COUNTER

OCMP1

FFFC FFFD FFFE

34E2

OLVL2

2ED0 2ED1 2ED2

OLVL1

34E2 FFFC

OLVL2

compare2 compare1 compare2

Note: OC1R=2ED0h, OC2R=34E2, OLVL1=0, OLVL2= 1

Note: On timers with only 1 Out put Compare register, a f ixed frequency PWM signal can be g enerated us-

ing the output compare and the counter overflow to define the pulse length.

80/215

16-BIT TIMER (Cont’d)

10.4.3.6 Pulse Width Modulation Mode

Pulse Width Modulation (PWM) mode enables the generation of a signal with a frequency and pulse length determined by the value of the OC1R and OC2R registers.

Pulse Width Modulation mode uses the complete Output Compare 1 function plus the OC2R register, and so this functionality can not be used when PWM mode is activated.

In PWM mode, double buffering is implemen ted on the output compare registers. Any new values written in the OC1R and OC2R registers are taken into account only at the end of the PWM period (OC2) to avoid spikes on the PWM output pin (OCMP1).

Procedure

To use pulse width modulation mode:

1. Load the OC2R register with the value corresponding to the period of the signal using the formula in the opposite column.

2. Load the OC1R register with the value corresponding to the period of the pulse if (OLVL1=0 and OLVL2=1) using the formula in the opposite column.

3. Select the following in the CR1 register: – Using the OLVL1 bit, select the level to be ap-

plied to the OCMP1 pin after a successful comparison with the OC1R register.

– Using the OLVL2 bit, select the level to be ap-

plied to the OCMP1 pin after a successful comparison with the OC2R register.

4. Select the following in the CR2 register: – Set OC1E bit: the OCMP1 pin is then dedi cat-

ed to the output compare 1 function. – Set the PWM bit. – Select the timer clock (CC[1:0]) (see T able 16

Clock Control Bits).

Pulse Width Modulation cycle

When

Counter

OCMP1 = OLVL1

= OC1R

When

Counter = OC2R

OCMP1 = OLVL2

Counter is reset

to FFFCh

ST72F521, ST72521B

If OLVL1=1 and OLVL2=0 the length of the positive pulse is the difference between t he OC2R and OC1R registers.

If OLVL1=OLVL2 a continuous signal will be seen on the OCMP1 pin.

The OC ing application can be calculated using the following formula:

Where: t = Signal or pulse period (in seconds)

CPU

PRESC

If the timer clock is an external clock the formula is:

Where: t = Signal or pulse period (in seconds) f

EXT

The Output Compare 2 event causes the counter to be initialized to FFFCh (See Figure 52)

Notes:

1. After a write instruction to the OCiHR register,

2. The OCF1 and OCF2 bits cannot be set by

3. The ICF1 bit is set by hardware when the coun-

4. In PWM mode the ICAP1 pin can not be used

5. When the Pulse Width Modulation (PWM) and

iR register value required for a specific ti m-

OCiR Value =

CPU

PRESC

- 5

= CPU clock frequency (in hertz)

= Timer prescaler factor (2, 4 or 8 depend-

ing on CC[1:0] bits, see Table 16 Clock

Control Bits)

OCiR = t

* fEXT

-5

= External timer clock frequency (in hertz)

the output compare function is inhibited until the OCiLR register is also written.

hardware in PWM mode therefore the Output Compare interrupt is inhibited.

ter reaches the OC2R value and can produce a timer interrupt if the ICIE bit is set and the I bit is cleared.

to perform input capture because it is disconnected to the timer. The ICAP2 pin can be used to perform input capture (ICF2 can be set and IC2R can be loaded) but the user must take care that the counter is reset each period and ICF1 can also generates interrupt if ICIE is set.

One Pulse Mode (OPM) bits are both set, the PWM mode is the only active one.

ICF1 bit is set

81/215

ST72F521, ST72521B

16-BIT TIMER (Cont’d)

10.4.4 Low Power Modes

Mode Description

WAIT

HALT

10.4.5 Interrupts

Input Capture 1 event/Counter reset in PWM mode ICF1 Input Capture 2 event ICF2 Yes No Output Compare 1 event (not available in PWM mode) OCF1 Output Compare 2 event (not available in PWM mode) OCF2 Yes No Timer Overflow event TOF TOIE Yes No

No effect on 16-bit Timer. Timer interrupts cause the device to exit from WAIT mode.

16-bit Timer registers are frozen. In HALT mode, the counter stops counting until Halt mode is exited. Counting resumes from the previous

count when the MCU is woken up by an interrupt with “exit from HALT mode” capability or from the counter reset value when the MCU is woken up by a RESET.

If an input capture event occurs on the ICAPi pin, the input capture detection circuitry is armed. Consequently, when the MCU is woken up by an interrupt with “exit from HALT mode” capability, the ICFi bit is set, and the counter value present when exiting from HALT mode is captured into the ICiR register.

Interrupt Event

Event

Flag

Enable

Control

Bit

ICIE

OCIE

Exit from Wait

Yes No

Exit

from

Halt

Note: The 16-bit Timer interrupt events are connected to the same interrupt vector (see Interrupts chap-

ter). These events generate an int errupt if the corresponding Enable Control Bit is set and the interrupt mask in the CC register is reset (RIM instruction).

10.4.6 Summary of Timer modes

MODES

Input Capture (1 and/or 2) Yes Yes Yes Yes Output Compare (1 and/or 2) Yes Yes Yes Yes One Pulse Mode No Not Recommended PWM Mode No Not Recommended

Input Capture 1 Input Capture 2 Output Compare 1 Output Compare 2

TIMER RESOURCES

No Partially No No

1) See note 4 in Section 10.4.3.5 One Pulse Mode

2) See note 5 in Section 10.4.3.5 One Pulse Mode

3) See note 4 in Section 10.4.3.6 Pulse Width Modulation Mode

82/215

16-BIT TIMER (Cont’d)

10.4.7 Register Description

Each Timer is associated with three control and status registers, and with six pairs of data registers (16-bit values) relating to the two input captures, the two output compares, the counter and the alternate counter.

ST72F521, ST72521B

Bit 4 = FOLV2 Forced Output Compare 2. This bit is set and cleared by software. 0: No effect on the OCMP2 pin. 1:Forces the OLVL2 bit to be copied to the

OCMP2 pin, if the OC2E bit is set and even if there is no successful comparison.

CONTROL REGISTER 1 (CR1)

Read/Write Reset Value: 0000 0000 (00h)

ICIE O C IE TOIE FOLV2 FOLV1 OLVL2 IEDG1 OLVL1

Bit 3 = FOLV1 Forced Output Compare 1. This bit is set and cleared by software. 0: No effect on the OCMP1 pin. 1: Forces OLVL1 to be copied to the OCMP1 pin, if

the OC1E bit is set and even if there is no successful comparison.

Bit 2 = OLVL2 Output Level 2.

Bit 7 = ICIE Input Capture Interrupt Enable. 0: Interrupt is inhibited. 1: A timer interrupt is generated whenever the

ICF1 or ICF2 bit of the SR register is set.

Bit 6 = OCIE Output Compare Interrupt Enable. 0: Interrupt is inhibited. 1: A timer interrupt is generated whenever the

OCF1 or OCF2 bit of the SR register is set.

This bit is copied to the OCMP2 pin whenever a successful comparison occurs with the OC2R register and OCxE is set in the CR2 register. This value is copied to the OCMP1 pin in One Pulse Mode and Pulse Width Modulation mode.

Bit 1 = IEDG1 Input Edge 1. This bit determines which type of level transition on the ICAP1 pin will trigger the capture. 0: A falling edge triggers the capture. 1: A rising edge triggers the capture.

Bit 5 = TOIE Timer Overflow Interrupt Enable. 0: Interrupt is inhibited. 1: A timer interrupt is enabled whenever the TOF

bit of the SR register is set.

Bit 0 = OLVL1 Output Level 1. The OLVL1 bit is copied to the OCMP1 pin whenever a successful comparison occurs with the OC1R register and the OC1E bit is set in the CR2 register.

83/215

ST72F521, ST72521B

16-BIT TIMER (Cont’d) CONTROL REGISTER 2 (CR2)

Read/Write Reset Value: 0000 0000 (00h)

OC1E OC2E OPM PWM CC1 CC0 IEDG2 EXEDG

Bit 4 = PWM Pulse Width Modulation. 0: PWM mode is not active. 1: PWM mode is active, the OCMP1 pin outputs a

programmable cyclic signal; the length of the pulse depends on the value of OC1R register; the period depends on the value of OC2R register.

Bit 7 = OC1E Output Compare 1 Pin Enable. This bit is used only to output the signal from the timer on the OCMP1 pin (OLV1 in Output Compare mode, both OLV1 and OLV2 in PWM and one-pulse mode). Whatever the value of the OC1E bit, the Output Compare 1 function of the timer remains active. 0: OCMP1 pin alternate function disabled (I/O pin

free for general-purpose I/O).

1: OCMP1 pin alternate function enabled.

Bit 6 = OC2E Output Compare 2 Pin Enable. This bit is used only to output the signal from the timer on the OCMP2 pin (OLV2 in Output Compare mode). Whatever the value of the OC2E bit, the Output Compare 2 function of the timer remains active. 0: OCMP2 pin alternate function disabled (I/O pin

free for general-purpose I/O).

1: OCMP2 pin alternate function enabled.

Bit 5 = OPM One Pulse Mode. 0: One Pulse Mode is not active. 1: One Pulse Mode is active, the ICAP1 pin can be

used to trigger one pulse on the OCMP1 pin; the active transition is given by the IEDG1 bit. The length of the generated pulse depends on the contents of the OC1R register.

Bit 3, 2 = CC[1:0] Clock Control. The timer clock mode depends on these bits:

Table 16. Clock Control Bits

Timer Clock CC1 CC0

/ 4 0 0

CPU

/ 2 0 1

CPU

/ 8 1 0

CPU

External Clock (where

available)

Note: If the external clock pin is not available , programming the external clock configuration stops the counter.

Bit 1 = IEDG2 Input Edge 2. This bit determines which type of level transition on the ICAP2 pin will trigger the capture. 0: A falling edge triggers the capture. 1: A rising edge triggers the capture.

Bit 0 = EXEDG External Clock Edge. This bit determines which type of level transition on the external clock pin EXTCLK will trigger the counter register. 0: A falling edge triggers the counter register. 1: A rising edge triggers the counter register.

84/215

ST72F521, ST72521B

16-BIT TIMER (Cont’d) CONTROL/STATUS REGISTER (CSR)

Read/Write (bits 7:3 read only) Reset Value: xxxx x0xx (xxh)

ICF1 OCF1 TOF ICF2 OCF2 TIMD 0 0

Bit 7 = ICF1 Input Capture Flag 1. 0: No input capture (reset value). 1: An input capture has occurred on the ICAP1 pin

or the counter has reached the OC2R value in PWM mode. To clear this bit, first read the SR register, then read or write the low byte of the IC1R (IC1LR) register.

Bit 6 = OCF1 Output Compare Flag 1. 0: No match (reset value). 1: The content of the free running counter has

matched the content of the OC1R register. To clear this bit, first read the SR register, then read or write the low byte of the OC1R (OC1LR) register.

Bit 5 = TOF Timer Overflow Flag. 0: No timer overflow (reset value). 1:The free running counter rolled over from FFFFh

to 0000h. To clear this bit, first read the SR register, then read or write the low byte of the CR (CLR) register.

Note: Reading or writing the ACLR register does not clear TOF.

Bit 4 = ICF2 Input Capture Flag 2. 0: No input capture (reset value). 1: An input capture has occurred on the ICAP2

pin. To clear this bit, first read the SR register, then read or write the low byte of the IC2R (IC2LR) register.

Bit 3 = OCF2 Output Compare Flag 2. 0: No match (reset value). 1: The content of the free running counter has

matched the content of the OC2R register. To clear this bit, first read the SR register, then read or write the low byte of the OC2R (OC2LR) register.

Bit 2 = TIMD Timer disable. This bit is set and cleared by software. When set, it freezes the timer presca ler and counter an d disabled the output functions (OCMP1 and OCMP2 pins) to reduce power consumption. Access to the timer registers is still available, allowing the timer configuration to be changed, or the counter reset, while it is disabled. 0: Timer enabled 1: Timer prescaler, counter and outputs disabled

Bits 1:0 = Reserved, must be kept cleared.

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ST72F521, ST72521B

16-BIT TIMER (Cont’d) INPUT CAPTURE 1 HIGH REGISTER (IC1HR)

Read Only Reset Value: Undefined

This is an 8-bit read only register that contains the high part of the counter value (transferred by the input capture 1 event).

OUTPUT COMPARE 1 HIGH REGISTER (OC1HR)

Read/Write Reset Value: 1000 0000 (80h)

This is an 8-bit register that contains the high part of the value to be compared to the CHR register.

MSB LSB

INPUT CAPTURE 1 LOW REGISTER (IC1LR)

Read Only Reset Value: Undefined

This is an 8-bit read only register that contains the low part of the counter value (transferred by the input capture 1 event).

MSB LSB

OUTPUT COMPARE 1 LOW REGISTER (OC1LR)

Read/Write Reset Value: 0000 0000 (00h)

This is an 8-bit register that contains the low part of the value to be compared to the CLR register.

MSB LSB

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16-BIT TIMER (Cont’d) OUTPUT COMPARE 2 HIGH REGISTER

(OC2HR)

Read/Write Reset Value: 1000 0000 (80h)

This is an 8-bit register that contains the high part of the value to be compared to the CHR register.

ST72F521, ST72521B

ALTERNATE COUNTER HIGH REGISTER (ACHR)

Read Only Reset Value: 1111 1111 (FFh)

This is an 8-bit register that contains the high part of the counter value.

MSB LSB

OUTPUT COMPARE 2 LOW REGISTER (OC2LR)

Read/Write Reset Value: 0000 0000 (00h)

This is an 8-bit register that contains the low part of the value to be compared to the CLR register.

MSB LSB

ALTERNATE COUNTER LOW REGISTER (ACLR)

Read Only Reset Value: 1111 1100 (FCh)

This is an 8-bit register that contains the low part of the counter value. A write to this register resets the counter. An access to this register aft er an access to CSR register does not clear the TOF bit in the CSR register.

MSB LSB

COUNTER HIGH REGISTER (CHR)

MSB LSB

Read Only Reset Value: 1111 1111 (FFh)

This is an 8-bit register that contains the high part of the counter value.

INPUT CAPTURE 2 HIGH REGISTER (IC2HR) Read Only

Reset Value: Undefined This is an 8-bit read only register that conta ins the

high part of the counter value (transferred by the

MSB LSB

Input Capture 2 event).

COUNTER LOW REGISTER (CLR)

MSB LSB

Read Only Reset Value: 1111 1100 (FCh)

This is an 8-bit register that contains the low part of the counter value. A write to this register resets the counter. An access to this register after accessing the CSR register clears the TOF bit.

INPUT CAPTURE 2 LOW REGISTER (IC2LR)

Read Only Reset Value: Undefined

This is an 8-bit read only register that conta ins the low part of the counter value (transferred by the Input Capture 2 event).

MSB LSB

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ST72F521, ST72521B

16-BIT TIMER (Cont’d) Table 17. 16-Bit Timer Register Map and Reset Values

Address

(Hex.)

Timer A: 32 Timer B: 42

Timer A: 31 Timer B: 41

Timer A: 33 Timer B: 43

Timer A: 34 Timer B: 44

Timer A: 35 Timer B: 45

Timer A: 36 Timer B: 46

Timer A: 37 Timer B: 47

Timer A: 3E Timer B: 4E

Timer A: 3F Timer B: 4F

Timer A: 38 Timer B: 48

Timer A: 39 Timer B: 49

Timer A: 3A Timer B: 4A

Timer A: 3B Timer B: 4B

Timer A: 3C Timer B: 4C

Timer A: 3D Timer B: 4D

Label

CR1

Reset Value

CR2

Reset Value

CSR

Reset Value

IC1HR

Reset Value

IC1LR

Reset Value

OC1HR

Reset Value

OC1LR

Reset Value

OC2HR

Reset Value

OC2LR

Reset Value

CHR

Reset Value

CLR

Reset Value

ACHR

Reset Value

ACLR

Reset Value

IC2HR

Reset Value

IC2LR

Reset Value

76543210

ICIE

OC1E

ICF1

MSB

xxxxxxx

MSB

xxxxxxx

MSB

1000000

MSB

0000000

MSB

1000000

MSB

0000000

MSB

1111111

MSB

1111110

MSB

1111111

MSB

1111110

MSB

xxxxxxx

MSB

xxxxxxx

OCIE

OC2E

OCF1

TOIE0FOLV20FOLV10OLVL20IEDG10OLVL1

OPM

TOF

PWM

ICF2

CC1

OCF2

CC0

TIMD

IEDG20EXEDG

LSB

Related Documentation

AN 973: SCI software communications using 16bit timer

AN 974: Real Time Clock with ST7 Timer Output Compare

AN 976: Driving a buzzer through the ST7 Timer PWM function

88/215

AN1041: Using ST7 PWM signal to generate analog input (sinusoid)

AN1046: UART emulation software AN1078: PWM duty cycle switch implementing

true 0 or 100 per cent duty cycle AN1504: Starting a PWM signal directly at high

level using the ST7 16-Bit timer

10.5 SERIAL PERIPHERAL INTERFACE (SPI)

ST72F521, ST72521B

10.5.1 Introduction

The Serial Peripheral Interface (SPI) allows fullduplex, synchronous, serial communication with external devices. An SPI system may consist of a master and one or more slaves however the SPI interface can not be a master in a multi-master system.

10.5.2 Main Features

■ Full duplex synchronous transfers (on 3 lines)

■ Simplex synchronous transfers (on 2 lines)

■ Master or slave operation

■ Six master mode frequencies (f

■ f

/2 max. slave mode frequency (see note)

CPU

■ SS Management by software or hardware

■ Programmable clock polarity and phase

■ End of transfer interrupt flag

■ Write collision, Master Mode Fa ult a nd Ov erru n

CPU

/4 max.)

flags

Figure 53. Serial Peripheral Interface Block Diagram

Data/Address Bus

SPIDR

Read Buffer

Read

Note: In slave mode, continuous transmission is not possible at maximum frequency due to the software overhead for clearing st atus flags and to initiate the next transmission sequence.

10.5.3 General Description

Figure 53 shows the serial peripheral interface

(SPI) block diagram. There are 3 registers:

– SPI Control Register (SPICR) – SPI Control/Status Register (SPICSR) – SPI Data Register (SPIDR)

The SPI is connected to external devices through 4 pins:

– MISO: Master In / Slave Out data – MOSI: Master Out / Slave In data – SCK: Serial Clock out by SPI masters an d in-

put by SPI slaves

Interrupt request

MOSI

MISO

SCK

SOD

bit

8-Bit Shift Register

Write

MASTER

CONTROL

SERIAL CLOCK

GENERATOR

SPIF WCOL MODF

SPIE SPE

OVR SSISSMSOD

SPI

STATE

CONTROL

MSTR

SPR2

CPOL

CPHA

SPICSR

SPICR

SPR1

SPR0

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ST72F521, ST72521B

SERIAL PERIPHERAL INTERFACE (Cont’d)

–SS

: Slave select: This input signal acts as a ‘chip select’ to let the SPI master communicate with slaves individually and to avoid contention on the data lines. Slave SS ard I/O ports on the master MCU.

10.5.3.1 Functional Description

A basic example of interconnections between a single master and a single slave is illustrated in

Figure 54.

The MOSI pins are connected together and the MISO pins are connected together. In this way data is transferred serially between master and slave (most significant bit first).

Figure 54. Single Master/ Single Slave Application

inputs can be driven by stand-

The communication is always initiated by the master. When the master device transmits data to a slave device via MOSI pin, the slave device responds by sending data to the master device via the MISO pin. This implies full duplex communication with both data out and data in synchronized with the same clock signal (which is provided by the master device via the SCK pin).

To use a single data line, the MISO and MOSI p ins must be connected at each node ( in this case only simplex communication is possible).

Four possible data/clock timing relationships may be chosen (see Figure 57) but master and slave must be programmed with the same timing mode.

MASTER

MSBit LSBit MSBit LSBit 8-BIT SHIFT REGISTER

SPI

CLOCK

GENERATOR

MISO

MOSI

SCK

+5V

MISO

MOSI

SCK

8-BIT SHIFT REGISTER

SLAVE

Not used if SS is managed by software

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SERIAL PERIPHERAL INTERFACE (Cont’d)

10.5.3.2 Slave Select Management

As an alternative to using the SS

pin to control the Slave Select signal, the application can choose to manage the Slave Select signal by software. This is configured by the SSM bit in the SPICSR register (see Figure 56)

In software management, the external SS

pin is free for other application uses and th e intern al SS signal level is driven by writing to the SSI bit in the SPICSR register.

In Master mode:

–SS

internal must be held high continuously

ST72F521, ST72521B

In Slave Mode:

There are two cases depending on the data/clock timing relationship (see Figure 55):

If CPHA=1 (data latched on 2nd clock edge):

–SS

internal must be held low during the entire transmission. This implies that in single slave applications the SS V

, or made free for standard I/O b y mana g-

ing the SS

function by software (SSM= 1 and

SSI=0 in the in the SPICSR register)

If CPHA=0 (data latched on 1st clock edge):

–SS

internal must be held low during byte transmission and pulled high between each byte to allow the slave to write to the shift register. If SS

is not pulled high, a Write Collision error will occur when the s lave writes to the shift register (see Section 10.5.5.3).

pin either can be tied to

Figure 55. Generic SS

MOSI/MISO

Master SS

Slave SS

(if CPHA=0)

Slave SS

(if CPHA=1)

Timing Diagram

Byte 1 Byte 2

Figure 56. Hardware/Software Slave Select Management

SSM bit

external pin

SSI bit

SS internal

Byte 3

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ST72F521, ST72521B

SERIAL PERIPHERAL INTERFACE (Cont’d)

10.5.3.3 Master Mode Operation

In master mode, the serial clock is output on the SCK pin. The clock frequency, polarity and phase are configured by software (refer to the description of the SPICSR register).

Note: The idle state of SCK must correspond to the polarity selected in the SPICSR register (by pulling up SCK if CPOL=1 or pulling down SCK if CPOL=0).

To operate the SPI in master mode, perform the following steps in order (if the SPICSR register is not written first, the SPICR register setting (M STR bit) may be not taken into account):

1. Write to the SPICR register: – Select the clock frequency by configuring the

SPR[2:0] bits.

– Select the clock polarity and c lock phase by

configuring the CPOL and CPHA bits. Figure

57 shows the four possible configurations.

Note: T he slave must have the same CPOL and CPHA settings as the master.

2. Write to the SPICSR register: – Either set the SSM bit and set the SSI bit or

clear the SSM bit and t ie the SS the complete byte transmit sequence.

3. Write to the SPICR register: – Set the MSTR and SPE bits

Note: MSTR and SPE bits remain set only if SS

is high).

The transmit sequence begins when software writes a byte in the SPIDR register.

10.5.3.4 Master Mode Transmit Sequence

When software writes to t he SPIDR register, the data byte is loaded into the 8-bit shift register and then shifted out serially to the MOSI pin most significant bit first.

When data transfer is complete:

– The SPIF bit is set by hardware – An interrupt request is generated if the SPIE

bit is set and the interrupt mask in the CCR register is cleared.

Clearing the SPIF bit is performed by the following software sequence:

1. An access to the SPICSR register while the SPIF bit is set

2. A read to the SPIDR register.

pin high for

Note: While the SPIF bit is set, all writes to the SPIDR register are inhibited until the SPICSR register is read.

10.5.3.5 Slave Mode Operation

In slave mode, the serial clock is received on the SCK pin from the master device.

To operate the SPI in slave mode:

1. Write to the SPICSR register to perform the following actions:

– Select the clock polarity and clock phase by

configuring the CPOL and CPHA bits (see

Figure 57).

Note: The slave must have the sa me CPOL and CPHA settings as the master.

– Manage the SS

10.5.3.2 and Figure 55. If CPHA=1 SS

be held low continuously. If CPHA=0 SS be held low during byte transmission and pulled up between each byte to let the slave write in the shift register.

2. Write to the SPICR register to clear the MSTR bit and set the SPE bit to enable the SPI I/O functions.

10.5.3.6 Slave Mode Transmit Sequence

When software writes to the SPIDR register, the data byte is loaded into the 8-bit shift register and then shifted out serially to the MISO pin most significant bit first.

The transmit sequence begins when the s lav e de vice receives the clock signal and the most significant bit of the data on its MOSI pin.

When data transfer is complete:

– The SPIF bit is set by hardware – An interrupt request is generated if SPIE bit is

set and interrupt mask in the CCR register is cleared.

Clearing the SPIF bit is performed by the following software sequence:

1. An access to the SPICSR register while the SPIF bit is set.

2. A write or a read to the SPIDR register .

Notes: While the SPIF bit is set, all writes to the SPIDR register are inhibited until the SPICSR register is read.

The SPIF bit can be cleared during a second transmission; however, it must be cleared before the second SPIF bit in order to prevent an Overrun condition (see Section 10.5.5.2).

pin as described in Section

must

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SERIAL PERIPHERAL INTERFACE (Cont’d)

10.5.4 Clock Phase and Clock Polarity

Four possible timing relationships may be chosen by software, using the CPOL and CPHA bits (See

Figure 57).

Note: The idle state of SCK must correspond to the polarity selected in the SPICSR register (by pulling up SCK if CPOL=1 or pulling down SCK if CPOL=0).

The combination of the CPOL clock polarity and CPHA (clock phase) bits selects the data capture clock edge

Figure 57. Data Clock Timing Diagram

SCK (CPOL = 1)

SCK (CPOL = 0)

ST72F521, ST72521B

Figure 57, shows an SPI transfer with the four

combinations of the CPHA and CPOL bits. The diagram may be interpreted as a master or slave timing diagram where the SCK pin, the MISO pin, the MOSI pin are directly connected between the master and the slave device.

Note: If CPOL is changed at the communication byte boundaries, the SPI must be disabled by resetting the SPE bit.

CPHA =1

MISO

(from master)

MOSI

(from slave)

(to slave)

CAPTURE STROBE

SCK (CPOL = 1)

SCK (CPOL = 0)

MISO

(from master)

MOSI

(from slave)

(to slave)

CAPTURE STROBE

MSBit Bit 6 Bit 5

Bit 4 Bit3 Bit 2 Bit 1 LSBit

Bit 4 Bit3Bit 2Bit 1LSBit

CPHA =0

Bit 4 Bit3 Bit 2 Bit 1 LSBit

Note: This figure should not be used as a replacement for parametric information. Refer to the Electrical Characteristics chapter.

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ST72F521, ST72521B

SERIAL PERIPHERAL INTERFACE (Cont’d)

10.5.5 Error Flags

10.5.5.1 Master Mode Fault (MODF)

Master mode fault occurs when the master device has its SS

When a Master mode fault occurs:

– The MODF bit is set and an SPI interrupt re-

– The SPE bit is reset. This blocks all output

– The MSTR bit is reset, thus forcing the device

Clearing the MODF bit is done through a software sequence:

1. A read access to the SPICSR register while the

2. A write to the SPICR register. Notes: To avoid any conflicts in an application

with multiple slaves, the SS high during the MODF bit clearing sequence. The SPE and MSTR bits may be restored to their original state during or after this clearing sequence.

Hardware does not allow the user to set the SPE and MSTR bits while the MODF bit is set except in the MODF bit clearing sequence.

10.5.5.2 Overrun Condition (OVR)

An overrun condition occurs, when the master device has sent a data byte and the slave device has

pin pulled low.

quest is generated if the SPIE bit is set.

from the device and disables the SPI peripheral.

into slave mode.

MODF bit is set.

pin must be pulled

not cleared the SPIF bit issued from the previously transmitted byte.

When an Overrun occurs: – The OVR bit is set and an interrupt request is

generated if the SPIE bit is set.

In this case, the receiver buffer contains the byte sent after the SPIF bit was last cleared. A read to the SPIDR register returns this byte. All other bytes are lost.

The OVR bit is cleared by reading the SPICSR register.

10.5.5.3 Write Collision Error (WCOL)

A write collision occurs when the software tries to write to the SPIDR register while a data transfer is taking place with an external device. When this happens, the transfer continues uninterrupted; and the software write will be unsuccessful.

Write collisions can occur both in master and slave mode. See also Section 10.5.3.2 Slave Select

Management.

Note: a "read collision" will never occur since the received data byte is placed in a buffer in which access is always synchronous with the MCU operation.

The WCOL bit in the SPICSR register is set if a write collision occurs.

No SPI interrupt is generated when the WCOL bit is set (the WCOL bit is a status flag only).

Clearing the WCOL bit is done through a software sequence (see Figure 58).

Figure 58. Clearing the WCOL bit (Write Collision Flag) Software Sequence

Clearing sequence after SPIF = 1 (end of a data byte transfer)

1st Step

2nd Step

Read SPICSR

Read SPIDR

RESULT

SPIF =0 WCOL=0

Clearing sequence before SPIF = 1 (during a data byte transfer)

1st Step

2nd Step

94/215

Read SPICSR

Read SPIDR

RESULT

WCOL=0

Note: Writin g to the SPIDR register instead of reading it does no t reset the WCOL bit

SERIAL PERIPHERAL INTERFACE (Cont’d)

10.5.5.4 Single Master Systems

A typical single master system may be configured, using an MCU as the master and four MCUs as slaves (see Figure 59).

The master device selects the individual slave devices by using four pins of a parallel port to co ntro l the four SS

The SS master device ports will be forced to be inputs at that time, thus disabling the slave devices.

Figure 59. Single Master / Multiple Slave Configuration

pins of the slave devices.

pins are pulled high during reset since the

Note: To prevent a bus conflict on the MISO line the master allows only one active slave device during a transmission.

For more security, the slave device may respond to the master with the received data byte. Then the master will receive the previous byte back from the slave device if all MISO and MOSI pins are connected and the slave has not written to its SPIDR register.

Other transmission security methods can use ports for handshake lines or data bytes with command fields.

ST72F521, ST72521B

SCK

MOSI

SCK

Master MCU

SS SS

SCK

Slave MCU

MOSI MOSI MOSIMISO MISO MISOMISO

MISO

Ports

Slave MCU

SCK SCK

Slave MCU

95/215

ST72F521, ST72521B

SERIAL PERIPHERAL INTERFACE (Cont’d)

10.5.6 Low Power Modes

Mode Description

WAIT

HALT

10.5.6.1 Using the SPI to wakeup the MCU f rom Halt mode

In slave configuration, the SPI is able to wakeup the ST7 device from HALT mode through a SPIF interrupt. The data received is subsequently read from the SPIDR register when the software is running (interrupt vector fetch). If multiple data transfers have been performed before software clears the SPIF bit, then the OVR bit is set by hardware.

No effect on SPI. SPI interrupt events cause the device to exit from WAIT mode.

SPI registers are frozen. In HALT mode, the SPI is inactive. SPI operation resumes when the MCU is woken up by an interrupt with “exit from HALT mode” capability. The data received is subsequently read from the SPIDR register when the software is running (interrupt vector fetching). If several data are received before the wakeup event, then an overrun error is generated. This error can be detected after the fetch of the interrupt routine that woke up the device.

Note: When waking up from Halt mode, if the SPI remains in Slave mode, it is recommended to perform an extra communications cycle to bring the SPI from Halt mode state to normal state. If the SPI exits from Slave mode, it returns to normal state immediately.

Caution: The SPI can wake up the ST7 from Halt mode only if the Slave Select signal (external SS pin or the SSI bit in the SPICSR register) is low when the ST7 enters Halt mode. So if Slave selection is configured as external (see Section

10.5.3.2), make sure the master drives a low level

on the SS

pin when the slave enters Halt mode.

10.5.7 Interrupts

Interrupt Event

SPI End of Transfer Event

Master Mode Fault Event

Overrun Error OVR Yes No

Event

Flag

SPIF

MODF Yes No

Enable

Control

Bit

SPIE

Exit from Wait

Yes Yes

Exit

from

Halt

Note: The SPI interrupt events are connected to

the same interrupt vector (see Interrupts chapter). They generate an interrupt if the corresponding Enable Control Bit is set and the interrupt mask in

96/215

ST72F521, ST72521B

SERIAL PERIPHERAL INTERFACE (Cont’d)

10.5.8 Register Description CONTROL REGISTER (SPICR)

Read/Write Reset Value: 0000 xxxx (0xh)

SPIE SPE SPR2 MSTR CPOL CPHA SPR1 SPR0

Bit 7 = SPIE Serial Peripheral Interrupt Enable. This bit is set and cleared by software. 0: Interrupt is inhibited 1: An SPI interrupt is generated whenever

SPIF=1, MODF=1 or OVR=1 in the SPICSR register

Bit 6 = SPE Serial Peripheral Output Enable. This bit is set and cleared by software. It is also cleared by hardware when, in master mode, SS

=0 (see Section 10.5.5.1 Master Mode Fault

(MODF)). The SPE bit is cleared by reset, so the

SPI peripheral is not initially connected to the external pins. 0: I/O pins free for general purpose I/O 1: SPI I/O pin alternate functions enabled

Bit 5 = SPR2 Divider Enable. This bit is set and cleared by software and is cleared by reset. It is used with the SPR[1:0] bits to set the baud rate. Refer to Table 18 SPI Master

mode SCK Frequency.

0: Divider by 2 enabled 1: Divider by 2 disabled

Note: This bit has no effect in slave mode.

Bit 4 = MSTR Master Mode. This bit is set and cleared by software. It is also cleared by hardware when, in master mode, SS

=0 (see Section 10.5.5.1 Master Mode Fault

(MODF)).

0: Slave mode 1: Master mode. The function of the SCK pin

changes from an input to an output and the fun ctions of the MISO and MOSI pins are reversed.

Bit 3 = CPOL Clock Polarity. This bit is set and cleared by software. T his bit determines the idle state of the serial Clock. The CPOL bit affects both the master and slave modes. 0: SCK pin has a low level idle state 1: SCK pin has a high level idle state

Note: If CPOL is changed at the communication byte boundaries, the SPI must be disabled by resetting the SPE bit.

Bit 2 = CPHA Clock Phase. This bit is set and cleared by software. 0: The first clock transition is the first data capture

edge.

1: The second clock transition is the first capture

edge.

Note: The slave must have the same CPOL and CPHA settings as the master.

Bits 1:0 = SPR[1:0] Serial Clock Frequency. These bits are set and cleared by software. Used with the SPR2 bit, they select th e ba ud rat e of the SPI serial clock SCK output by the SPI in master mode.

Note: These 2 bits have no effect in slave mode. Table 18. SPI Master mode SCK Frequency

Serial Clock SPR2 SPR1 SPR0

/4 1 0 0

CPU

/8 0 0 0

CPU

/16 0 0 1

CPU

/32 1 1 0

CPU

/64 0 1 0

CPU

/128 0 1 1

CPU

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ST72F521, ST72521B

SERIAL PERIPHERAL INTERFACE (Cont’d) CONTROL/STATUS REGISTER (SPICSR)

Read/Write (some bits Read Only) Reset Value: 0000 0000 (00h)

SPIF WCOL OVR MODF - SOD SSM SSI

Bit 7 = SPIF Serial Peripheral Data Transfer Flag

(Read only).

This bit is set by hardware when a transfer has been completed. An interrupt is generated if SPIE=1 in the SPICR register. It is cleared by a software sequence (an access to the SPICSR register followed by a write or a read to the SPIDR register).

0: Data transfer is in progress or the flag h as been

cleared.

1: Data transfer between the device and an exter-

nal device has been completed.

Note: While the SPIF bit is set, all writes to the SPIDR register are inhibited until the SPICSR register is read.

Bit 6 = WCOL Write Collision status (Read only). This bit is set by hardware when a write to the SPIDR register is done during a transmit sequence. It is cleared by a software sequence (see

Figure 58).

0: No write collision occurred 1: A write collision has been detected

Bit 5 = OVR SPI Overrun error (Read only). This bit is set by hardware when the byte currently being received in the shift register is ready to be transferred into the SPIDR regist er while SPIF = 1 (See Section 10.5.5.2). An interrupt is generated if SPIE = 1 in SPICR register. The OVR bit is cleared by software reading the SPICSR register . 0: No overrun error 1: Overrun error detected

Bit 4 = MODF Mode Fault flag (Read only). This bit is set by hardware when the SS

pin is pulled low in master mode (see Section 10.5.5.1

Master Mode Fault (MODF)). An SPI interrupt can

be generated if SPIE=1 in the SPICSR register. This bit is cleared by a software sequence (An access to the SPICR register while MODF=1 followed by a write to the SPICR register). 0: No master mode fault detected 1: A fault in master mode has been detected

Bit 3 = Reserved, must be kept cleared.

Bit 2 = SOD SPI Output Disable. This bit is set and cleared by software. When set, it disables the alternate function of the SPI output (MOSI in master mode / MISO in slave mode) 0: SPI output enabled (if SPE=1) 1: SPI output disabled

Bit 1 = SSM SS

Management.

This bit is set and cleared by software. When set, it disables the alternate function of the SPI SS and uses the SSI bit value instead. See Section

10.5.3.2 Slave Select Management.

0: Hardware management (S S

nal pin)

1: Software management (internal SS

trolled by SSI bit. External SS al-purpose I/O)

Bit 0 = SSI SS

Internal Mode.

This bit is set and cleared by software. It acts as a ‘chip select’ by controlling the level of the SS select signal when the SSM bit is set. 0 : Slave selected 1 : Slave deselected

DATA I/O REGISTER (SPIDR)

Read/Write Reset Value: Undefined

D7 D6 D5 D4 D3 D2 D1 D0

The SPIDR register is used to transmit and receive data on the serial bus. In a master device, a write to this register will initiate transmission/reception of another byte.

Notes: During the last clock cycle the SPIF bit is set, a copy of the received data byte in the shift register is moved to a buffer. When the user reads the serial peripheral data I/O register, the buffer is actually being read.

While the SPIF bit is set, all writes to the SPIDR register are inhibited until the SPICSR register is read.

Warning: A write to the SPIDR register places data directly into the shift register for transmission.

A read to the SPIDR register returns the value located in the buffer and not the content of the shift register (see Figure 53).

managed by exter-

signal con-

pin free for gener-

slave

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SERIAL PERIPHERAL INTERFACE (Cont’d) Table 19. SPI Register Map and Reset Values

ST72F521, ST72521B

Address

(Hex.)

0021h

0022h

0023h

Label

SPIDR

Reset Value

SPICR

Reset Value

SPICSR

Reset Value

76543210

MSB

xxxxxxx

SPIE

SPIF

SPE

WCOL

SPR20MSTR0CPOL

MODF

CPHA

SOD

SPR1

SSM

LSB

SPR0

SSI

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ST72F521, ST72521B

10.6 SERIAL COMMUNICATIONS INTERFACE (SCI)

10.6.1 Introduction

The Serial Communications Interface (SCI) offers a flexible means of full-duplex data exchange with external equipment requiring an industry standard NRZ asynchronous serial data format. The SCI offers a very wide range of baud rates using two baud rate generator systems.

10.6.2 Main Features

■ Full duplex, asynchronous communications

■ NRZ standard format (Mark/Space)

■ Dual baud rate generator systems

■ Independently programmable transmit and

receive baud rates up to 500K baud.

■ Programmable data word length (8 or 9 bits)

■ Receive buffer full, Transmit buffer empty and

End of Transmission flags

■ Two receiver wake-up modes:

– Address bit (MSB) – Idle line

■ Muting function for multiprocessor configura tions

■ Separate enable bits for Transmitter and

Receiver

■ Four error detection flags:

– Overrun error – Noise error – Frame error – Parity error

■ Five interrupt sources with flags:

– Transmit data register empty – Transmission complete – Receive data register full – Idle line received – Overrun error detected

■ Parity control:

– Transmits parity bit – Checks parity of received data byte

■ Reduced power consumption mode

10.6.3 General Description

The interface is externally connected to another device by two pins (see Figure 61):

– TDO: Transmit Data Output. When the transmit-

ter and the receiver are disabled, the output pin returns to its I/O port configuration. When the transmitter and/or the receiver are enabled and nothing is to be transmitted, the TDO pin is at high level.

– RDI: Receive Data Input is the serial data input.

Oversampling techniques are used for data re covery by discriminating between valid incoming data and noise.

Through these pins, serial data is transmitted and received as frames comprising:

– An Idle Line prior to transmission or reception – A start bit – A data word (8 or 9 bits) least significant bit first – A Stop bit indicating that the frame is complete. This interface uses two types of baud rate generator: – A conventional type for commonly-used baud

rates,

– An extended type with a prescaler offering a very

wide range of baud rates even with non-stand ard oscillator frequencies.

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ST ST72F521, ST72521B User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

1 INTRODUCTION

2 PIN DESCRIPTION

3 REGISTER & MEMORY MAP

4 FLASH PROGRAM MEMORY

4.1 Introduction

4.2 Main Features

4.3 Structure

4.3.1 Read-out Protection

4.4 ICC Interface

4.5 ICP (In-Circuit Programming)

4.6 IAP (In-Application Programming)

4.7 Related Documentation

4.7.1 Register Description FLASH CONTROL/STATUS REGISTER (FCSR)

5 CENTRAL PROCESSING UNIT

5.1 INTRODUCTION

5.2 MAIN FEATURES

5.3 CPU REGISTERS

6 SUPPLY, RESET AND CLOCK MANAGEMENT

6.1 PHASE LOCKED LOOP

6.2 MULTI-OSCILLATOR (MO)

6.3 RESET SEQUENCE MANAGER (RSM)

6.3.1 Introduction

6.3.3 External Power-On RESET

6.3.4 Internal Low Voltage Detector (LVD) RESET

6.3.5 Internal Watchdog RESET

6.4 SYSTEM INTEGRITY MANAGEMENT (SI)

6.4.1 Low Voltage Detector (LVD)

6.4.2 Auxiliary Voltage Detector (AVD)

6.4.2.2 Monitoring a Voltage on the EVD pin

6.4.3 Low Power Modes

6.4.3.1 Interrupts

6.4.4 Register Description SYSTEM INTEGRITY (SI) CONTROL/STATUS REGISTER (SICSR)

7 INTERRUPTS

7.1 INTRODUCTION

7.2 MASKING AND PROCESSING FLOW

7.3 INTERRUPTS AND LOW POWER MODES

7.4 CONCURRENT & NESTED MANAGEMENT

7.5 INTERRUPT REGISTER DESCRIPTION

7.6 EXTERNAL INTERRUPTS

7.6.1 I/O Port Interrupt Sensitivity

7.7 EXTERNAL INTERRUPT CONTROL REGISTER (EICR)

8 POWER SAVING MODES

8.1 INTRODUCTION

8.2 SLOW MODE

8.3 WAIT MODE

8.4 ACTIVE-HALT AND HALT MODES

8.4.1 ACTIVE-HALT MODE

8.4.2 HALT MODE

8.4.2.1 Halt Mode Recommendations

9 I/O PORTS

9.1 INTRODUCTION

9.2 FUNCTIONAL DESCRIPTION

9.2.1 Input Modes

9.2.2 Output Modes

9.2.3 Alternate Functions

9.3 I/O PORT IMPLEMENTATION

9.4 LOW POWER MODES

9.5 INTERRUPTS

9.5.1 I/O Port Implementation

10 ON-CHIP PERIPHERALS

10.1 WATCHDOG TIMER (WDG)

10.1.1 Introduction

10.1.2 Main Features

10.1.3 Functional Description

10.1.4 How to Program the Watchdog Timeout

10.1.5 Low Power Modes Mode Description

10.1.6 Hardware Watchdog Option

10.1.8 Interrupts

10.1.9 Register Description CONTROL REGISTER (WDGCR)

10.2 MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK AND BEEPER (MCC/RTC)

Programmable CPU Clock Prescaler

Clock-out Capability

Real Time Clock Timer (RTC)

Beeper

Low Power Modes

Interrupts