ST ST7232A User Manual

8-BIT MICROCONTROLLER WITH 8K FLASH/ROM,

ADC, 4 TIMERS, SPI, SCI INTERFACE

■ Memories

– 8K dual voltage High Density Flash (HDFlash)

or ROM with read-out protection capability. InApplication Programming and In-Circuit Pro-

gramming for HDFlash devices – 384 bytes RAM – HDFlash endurance: 100 cycles, data reten-

tion: 40 years at 85°C

■ Clock, Reset And Supply Management

– Clock sources: crystal/ceramic resonator os-

cillators 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 – 6 external interrupt lines (on 4 vectors)

■ Up to 32 I/O Ports

– 32/24 multifunctional bidirectional I/O lines – 22/17 alternate function lines – 12/10 high sink outputs

■ 4Timers

– Main Clock Controller with: Real time base,

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

output compares, PWM and pulse generator

modes

■ 2 Communications Interfaces

– SPI synchronous serial interface – SCI asynchronous serial interface

ST7232A

TQFP32

7 x 7

TQFP44

■ 1 Analog peripheral (low current coupling)

– 10-bit ADC with up to 12 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

SDIP32

400mil

SDIP42

Device Summary

Features

Program memory

- bytes RAM (stack) -

bytes Operating Voltage 3.8V to 5.5V 3.8V to 5.5V Temp. Range up to -40°C to +125°C up to -40°C to +125°C

Package

ST72F32AK1 ST72F32AK2 ST72F32AJ1 ST72F32AJ2 ST7232AK1 ST7232AK2 ST7232AJ1 ST7232AJ2

FLASH 4K FLASH 8K FLASH 4K FLASH 8K ROM 4K ROM 8K ROM 4K ROM 8K

384 (256) 384 (256)

SDIP32 400mils /

TQFP32 7x7

SDIP42 600mils /

TQFP44 10x10

SDIP32 400mils /

TQFP32 7x7

SDIP42 600mils /

TQFP44 10x10

Rev. 2

December 2005 1/157

Table of Contents

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

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

3 REGISTER & MEMORY MAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4 FLASH PROGRAM MEMORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.2 MAIN FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.3 STRUCTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.3.1 Read-out Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.4 ICC INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.5 ICP (IN-CIRCUIT PROGRAMMING) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.6 IAP (IN-APPLICATION PROGRAMMING) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.7 RELATED DOCUMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.7.1 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

5 CENTRAL PROCESSING UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

5.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

5.2 MAIN FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

5.3 CPU REGISTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

6 SUPPLY, RESET AND CLOCK MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

6.1 PHASE LOCKED LOOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

6.2 MULTI-OSCILLATOR (MO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

6.3 RESET SEQUENCE MANAGER (RSM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

6.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

6.3.2 Asynchronous External RESET pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

6.3.3 External Power-On RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

6.3.4 Internal Watchdog RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

6.4 SYSTEM INTEGRITY MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

6.4.1 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

7 INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

7.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

7.2 MASKING AND PROCESSING FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

7.3 INTERRUPTS AND LOW POWER MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

7.4 CONCURRENT & NESTED MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

7.5 INTERRUPT REGISTER DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

7.6 EXTERNAL INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

7.6.1 I/O Port Interrupt Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

7.7 EXTERNAL INTERRUPT CONTROL REGISTER (EICR) . . . . . . . . . . . . . . . . . . . . . . . 35

8 POWER SAVING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

8.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

8.2 SLOW MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

8.3 WAIT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

8.4 ACTIVE-HALT AND HALT MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

8.4.1 ACTIVE-HALT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

8.4.2 HALT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

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9 I/O PORTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.2 FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.2.1 Input Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.2.2 Output Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.2.3 Alternate Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.3 I/O PORT IMPLEMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

9.4 LOW POWER MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

9.5 INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

9.5.1 I/O Port Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

10 ON-CHIP PERIPHERALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

10.1 WATCHDOG TIMER (WDG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

10.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

10.1.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

10.1.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

10.1.4 How to Program the Watchdog Timeout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

10.1.5 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

10.1.6 Hardware Watchdog Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

10.1.7 Using Halt Mode with the WDG (WDGHALT option) . . . . . . . . . . . . . . . . . . . . . . . 51

10.1.8 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

10.1.9 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

10.2 MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK AND BEEPER (MCC/RTC) . 53

10.2.1 Programmable CPU Clock Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.2.2 Clock-out Capability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.2.3 Real Time Clock Timer (RTC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.2.4 Beeper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.2.5 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

10.2.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

10.2.7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

10.3 16-BIT TIMER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

10.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

10.3.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

10.3.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

10.3.4 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

10.3.5 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

10.3.6 Summary of Timer modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

10.3.7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

10.4 SERIAL PERIPHERAL INTERFACE (SPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

10.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

10.4.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

10.4.3 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

10.4.4 Clock Phase and Clock Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

10.4.5 Error Flags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

10.4.6 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

10.4.7 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

10.4.8 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

10.5 SERIAL COMMUNICATIONS INTERFACE (SCI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

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10.5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

10.5.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

10.5.3 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

10.5.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

10.5.5 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

10.5.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

10.5.7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

10.6 10-BIT A/D CONVERTER (ADC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

10.6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

10.6.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

10.6.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

10.6.4 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

10.6.5 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

10.6.6 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

11 INSTRUCTION SET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

11.1 CPU ADDRESSING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

11.1.1 Inherent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

11.1.2 Immediate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

11.1.3 Direct . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

11.1.4 Indexed (No Offset, Short, Long) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

11.1.5 Indirect (Short, Long) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

11.1.6 Indirect Indexed (Short, Long) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

11.1.7 Relative mode (Direct, Indirect) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

11.2 INSTRUCTION GROUPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

12 ELECTRICAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

12.1 PARAMETER CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

12.1.1 Minimum and Maximum values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

12.1.2 Typical values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

12.1.3 Typical curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

12.1.4 Loading capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

12.1.5 Pin input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

12.2 ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

12.2.1 Voltage Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

12.2.2 Current Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

12.2.3 Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

12.3 OPERATING CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

12.3.1 Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

12.4 SUPPLY CURRENT CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

12.4.1 CURRENT CONSUMPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

12.4.2 Supply and Clock Managers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

12.4.3 On-Chip Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

12.5 CLOCK AND TIMING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

12.5.1 General Timings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

12.5.2 External Clock Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

12.5.3 Crystal and Ceramic Resonator Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

12.5.4 PLL Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

12.6 MEMORY CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

157

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Table of Contents

12.6.1 RAM and Hardware Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

12.6.2 FLASH Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

12.7 EMC CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

12.7.1 Functional EMS (Electro Magnetic Susceptibility) . . . . . . . . . . . . . . . . . . . . . . . . 125

12.7.2 Electro Magnetic Interference (EMI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

12.7.3 Absolute Maximum Ratings (Electrical Sensitivity) . . . . . . . . . . . . . . . . . . . . . . . . 127

12.8 I/O PORT PIN CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

12.8.1 General Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

12.8.2 Output Driving Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

12.9 CONTROL PIN CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

12.9.1 Asynchronous RESET Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

12.9.2 ICCSEL/VPP Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

12.10 TIMER PERIPHERAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

12.10.116-Bit Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

12.11 COMMUNICATION INTERFACE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . 135

12.11.1SPI - Serial Peripheral Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

12.12 10-BIT ADC CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

12.12.1Analog Power Supply and Reference Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

12.12.2General PCB Design Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

12.12.3ADC Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

13 PACKAGE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

13.1 PACKAGE MECHANICAL DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

13.2 THERMAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

13.3 SOLDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

14 ST7232A DEVICE CONFIGURATION AND ORDERING INFORMATION . . . . . . . . . . . . . . . 145

14.1 FLASH OPTION BYTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

14.2 ROM DEVICE ORDERING INFORMATION AND TRANSFER OF CUSTOMER CODE 147

14.3 VERSION-SPECIFIC SALES CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

14.4 FLASH DEVICE ORDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

14.5 DEVELOPMENT TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

14.5.1 Socket and Emulator Adapter Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

14.6 ST7 APPLICATION NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

15 KNOWN LIMITATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

15.1 ALL FLASH AND ROM DEVICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

15.1.1 Safe Connection of OSC1/OSC2 Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

15.1.2 Unexpected Reset Fetch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

15.1.3 Clearing active interrupts outside interrupt routine . . . . . . . . . . . . . . . . . . . . . . . . 154

15.1.4 16-bit Timer PWM Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

15.1.5 SCI Wrong Break duration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

15.1.6 39-Pulse ICC Entry Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

15.2 ROM DEVICES ONLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

15.2.1 I/O Port A and F Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

15.2.2 External clock source with PLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

16 REVISION HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

157

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Table of Contents

To obtain the most recent version of this datasheet,

please check at www.st.com>products>technical literature>datasheet.

Please also pay special attention to the Section “KNOWN LIMITATIONS” on page 154.

6/157

157

ST7232A

1 INTRODUCTION

The ST72F32A and ST7232A devices are members of the ST7 microcontroller family designed for the 5V operating range.

The 32 and 44-pin devices are designed for midrange applications

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

Figure 1. Device Block Diagram

8-BIT CORE

ALU

RESET

OSC1 OSC2

CONTROL

OSC

MCC/RTC/BEEP

PORT F

Under software control, all devices can be placed in WAIT, SLOW, ACTIVE-HALT or HALT mode, 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 microcontrollers feature true bit manipulation, 8x8 unsigned multiplication and indirect addressing modes.

PROGRAM

MEMORY (8K Bytes)

RAM

(384 Bytes)

WATCHDOG

ADDRESS AND DATA BUS

PORT A

AREF

SSA

TIMER A

BEEP

PORT E

SCI

PORT D

10-BIT ADC

PORT B

PORT C

TIMER B

SPI

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ST7232A

2 PIN DESCRIPTION

Figure 2. 32-Pin SDIP Package Pinout

(HS) PB4

AIN0 / PD0 AIN1 / PD1

AREF

SSA

MCO / AIN8 / PF0

BEEP / (HS) PF1

OCMP1_A / AIN10 / PF4

ICAP1_A / (HS) PF6

EXTCLK_A / (HS) PF7

AIN12 / OCMP2_B / PC0 AIN13 / OCMP1_B / PC1

ICAP2_B / (HS) PC2 ICAP1_B / (HS) PC3

ICCDATA/ MISO / PC4

AIN14 / MOSI / PC5

Figure 3. 32-Pin TQFP 7x7 Package Pinout

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

ei3

ei1

ei0

ei2

PB3

PB0

PE1 / RDI

PE0 / TDO

28 27 26 25 24 23 22 21 20 19 18 17

OSC1 OSC2

VSS_2 RESET

PA7 (HS) PA6 (HS)

PA4 (HS) PA3 (HS) PC7 / SS / AIN15

PC6 / SCK / ICCCLK

/ ICCSEL

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

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AREF

MCO / AIN8 / PF0

BEEP / (HS) PF1

OCMP1_A / AIN10 / PF4

ICAP1_A / (HS) PF6

EXTCLK_A / (HS) PF7

AIN12 / OCMP2_B / PC0

SSA

PB0

PD1 / AIN1

PD0 / AIN0

PB4 (HS)

32 31 30 29 28 27 26 25

ei3

2 3

ei1

4 5 6 7 8

9 10111213141516

ICAP2_B / (HS) PC2

ICAP1_B / (HS) PC3

AIN13 / OCMP1_B / PC1

PB3

ei2

ICCDATA / MISO / PC4

AIN14 / MOSI / PC5

PE1 / RDI

ICCCLK / SCK / PC6

PE0 / TDO

ei0

AIN15 / SS / PC7

24 23 22 21 20 19 18 17

(HS) PA3

OSC1 OSC2 VSS_2 RESET V

/ ICCSEL

PA7 (HS) PA6 (HS) PA4 (HS)

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

PIN DESCRIPTION (Cont’d)

Figure 4. 42-Pin SDIP and 44-Pin TQFP Package Pinouts

ST7232A

RDI / PE1

(HS) PB4 AIN0 / PD0 AIN1 / PD1 AIN2 / PD2 AIN3 / PD3 AIN4 / PD4

PB0

PB1

PB2 PB3

1 2 3 4 5 6 7 8 9 10 11

(HS) PB4

AIN0 / PD0 AIN1 / PD1 AIN2 / PD2 AIN3 / PD3 AIN4 / PD4 AIN5 / PD5

AREF

SSA

MCO / AIN8 / PF0

BEEP / (HS) PF1

(HS) PF2

AIN10 / OCMP1_A / PF4

ICAP1_A / (HS) PF6

EXTCLK_A / (HS) PF7 AIN12 / OCMP2_B / PC0 AIN13 / OCMP1_B / PC1

ICAP2_B/ (HS) PC2

ICAP1_B / (HS) PC3

ICCDATA / MISO / PC4

AIN14 / MOSI / PC5

PE0 / TDO

OSC1

OSC2

_2 V

/ ICCSEL

RESET

PA7 (HS)

PA6 (HS)

PA5 (HS)

44 43 42 41 40 39 38 37 36 35 34

ei2

ei0

ei3

ei1

12 13 14 15 16 17 18 19 20 21 22

AIN5 / PD5

SSA

AREF

(HS) PF2

BEEP / (HS) PF1

MCO / AIN8 / PF0

OCMP1_A / AIN10 / PF4

ei3 2 3

ei2

4 5 6 7 8 9 10 11

ei1 12 13 14 15 16 17 18 19

ei0 20 21

DD_0

ICAP1_A / (HS) PF6

EXTCLK_A / (HS) PF7

42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22

PA4 (HS)

SS_1

DD_1

PA3 (HS)

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

PB3 PB2 PB1 PB0 PE1 / RDI PE0 / TDO VDD_2

OSC1

OSC2 VSS_2 RESET V

/ ICCSEL

PA7 (HS) PA6 (HS) PA5 (HS) PA4 (HS) V

SS_1

DD_1

PA3 (HS) PC7 / SS

/ AIN15

PC6 / SCK / ICCCLK

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

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ST7232A

PIN DESCRIPTION (Cont’d)

For external pin connection guidelines, refer to See “ELECTRICAL CHARACTERISTICS” on page 113.

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

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 42 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 ports

Pin n°

TQFP44

SDIP42

TQFP32

Pin Name

SDIP32

Level Port

Type

Input

Output

float

Input Output

wpu

int

ana

function

(after

reset)

Main

6 1 30 1 PB4 (HS) I/O CTHS X ei3 X X Port B4

7 2 31 2 PD0/AIN0 I/O C

8 3 32 3 PD1/AIN1 I/O C

9 4 PD2/AIN2 I/O C

10 5 PD3/AIN3 I/O C 11 6 PD4/AIN4 I/O C 12 7 PD5/AIN5 I/O C 13 8 1 4 V 14 9 2 5 V

AREF

SSA

S Analog Reference Voltage for ADC S Analog Ground Voltage

15 10 3 6 PF0/MCO/AIN8 I/O C

16 11 4 7 PF1 (HS)/BEEP I/O C 17 12 PF2 (HS) I/O C

18 13 5 8

PF4/OCMP1_A/ AIN10

I/O C

19 14 6 9 PF6 (HS)/ICAP1_A I/O C

20 15 7 10

21 V 22 V

23 16 8 11

PF7 (HS)/ EXTCLK_A

DD_0

SS_0

PC0/OCMP2_B/ AIN12

I/O C

S Digital Main Supply Voltage S Digital Ground Voltage

I/O C

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 X X X X Port D4 ADC Analog Input 4 X X X X X Port D5 ADC Analog Input 5

X ei1 X X X Port F0

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

X XXXXPort F4

HS X X X X Port F6 Timer A Input Capture 1

HS X XXXPort F7

X XXXXPort C0

Alternate Function

)

ADC Analog Input 8

ADC Analog Input 10

Main clock out (f

CPU

Timer A Output Compare 1

Timer A External Clock Source

Timer B Output Compare 2

ADC Analog Input 12

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ST7232A

Pin n°

Pin Name

SDIP42

TQFP44

24 17 9 12

SDIP32

TQFP32

PC1/OCMP1_B/ AIN13

25 18 10 13 PC2 (HS)/ICAP2_B I/O C 26 19 11 14 PC3 (HS)/ICAP1_B I/O C

27 20 12 15

PC4/MISO/ICCDATA

28 21 13 16 PC5/MOSI/AIN14 I/O C

29 22 14 17 PC6/SCK/ICCCLK I/O C

30 23 15 18 PC7/SS/AIN15 I/O C

31 24 16 19 PA3 (HS) I/O C 32 25 V 33 26 V

DD_1

SS_1

34 27 17 20 PA4 (HS) I/O C 35 28 PA5 (HS) I/O C 36 29 18 21 PA6 (HS) I/O C 37 30 19 22 PA7 (HS) I/O CTHS X TPort A7

Level Port

Type

Input

Output

float

Input Output

wpu

int

ana

function

(after

reset)

Main

Alternate Function

Timer B Out-

I/O C

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

I/O C

X XXXPort C4

In / Slave Out Data

SPI Master

X XXXXPort C5

Out / Slave In Data

X XXXPort C6

SPI Serial Clock

SPI Slave

X XXXXPort C7

Select (active low)

HS X ei0 X X Port A3

S Digital Main Supply Voltage S Digital Ground Voltage

HS X XXXPort A4

HS X XXXPort A5

HS X TPort A6

ADC Analog Input 13

ICC Data Input

ADC Analog Input 14

ICC Clock Output

ADC Analog Input 15

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

38 31 20 23 V

/ICCSEL I

programming voltage input V

Section 12.9.2 for more details. High

. See

voltage must not be applied to ROM

devices. 39 32 21 24 RESET 40 33 22 25 V

SS_2

I/O C

S Digital Ground Voltage

Top priority non maskable interrupt.

41 34 23 26 OSC2 O Resonator oscillator inverter output

42 35 24 27 OSC1 I

43 36 25 28 V

DD_2

S Digital Main Supply Voltage

44 37 26 29 PE0/TDO I/O C

1 382730 PE1/RDI I/OC

X X X X Port E0 SCI Transmit Data Out X X X X Port E1 SCI Receive Data In

External clock input or Resonator os-

cillator inverter input

Caution: Negative cur-

2 392831 PB0 I/OC

3 40 PB1 I/O C 4 41 PB2 I/O C 5 422932 PB3 I/OC

X ei2 X X Port B0

X ei2 X X Port B1 X ei2 X X Port B2 X ei2 X X Port B3

rent injection not allowed on this pin

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ST7232A

Notes:

1. In the interrupt input column, “eiX” defines the associated external interrupt vector. If the weak pull-up column (wpu) is merged with the interrupt column (int), then the I/O configuration is pull-up interrupt 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 diode to V are not implemented). See See “I/O PORTS” on page 42. 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 has 8 pads. Pads that are not bonded to external pins are in input pull-up configuration after reset. The configuration of these pads must be kept at reset state to avoid added current consumption.

5. For details refer to Section 12.8.1 on page 128

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3 REGISTER & MEMORY MAP

ST7232A

As shown in Figure 5, 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 384 bytes of RAM and up to 8 Kbytes of user program memory. The RAM space includes up to 256 bytes for the stack from 0100h to 01FFh.

Figure 5. Memory Map

0000h

007Fh 0080h

047Fh 0480h

E000h

FFDFh FFE0h

FFFFh

HW Registers

(see Table 2)

RAM

(384 Bytes)

Reserved

Program Memory

(4K or 8K)

Interrupt & Reset Vectors

(see Table 8)

0080h

00FFh

0100h

01FFh

0200h

027Fh

or 047Fh

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

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

Short Addressing RAM (zero page)

256 Bytes Stack

Reserved

E000h

8 KBytes

F000h

4 Kbytes

FFFFh

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ST7232A

Table 2. Hardware Register Map

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

0020h

Label

PADR PADDR PAOR

PBDR PBDDR PBOR

PCDR PCDDR PCOR

PDADR

PDDDR PDOR

PEDR PEDDR PEOR

PFDR PFDDR PFOR

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

Reset

Status

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

Reserved Area (15 Bytes)

0021h 0022h 0023h

0024h 0025h 0026h 0027h

SPI

ITC

SPIDR SPICR SPICSR

ISPR0 ISPR1 ISPR2 ISPR3

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

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

xxh 0xh 00h

FFh FFh FFh FFh

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 Reserved Area (1 Byte)

002Ch 002Dh

MCC

MCCSR MCCBCR

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

00h 00h

002Eh

Reserved Area (3 Bytes)

0030h

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R/W R/W R/W

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

R/W R/W

ST7232A

Address Block

0031h 0032h 0033h 0034h 0035h 0036h 0037h 0038h 0039h 003Ah 003Bh 003Ch 003Dh 003Eh 003Fh

0040h Reserved Area (1 Byte)

0041h 0042h 0043h 0044h 0045h 0046h 0047h 0048h 0049h 004Ah 004Bh 004Ch 004Dh 004Eh 004Fh

TIMER A

TIMER B

Label

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

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

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

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

Reset

Status

00h 00h

xxxx x0xxb

xxh

xxh 80h 00h FFh FCh FFh FCh

xxh

xxh 80h 00h

00h 00h

xxxx x0xxb

xxh

xxh 80h 00h FFh FCh FFh FCh

xxh

xxh 80h 00h

Remarks

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

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

0058h

006Fh

0070h 0071h 0072h

0073h 007Fh

SCI

ADC

SCISR SCIDR SCIBRR SCICR1 SCICR2 SCIERPR

SCIETPR

ADCCSR ADCDRH ADCDRL

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

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 (24 Bytes)

Control/Status Register Data High Register Data Low Register

Reserved Area (13 Bytes)

C0h

xxh 00h

x000 0000h

00h 00h

---

00h

00h 00h 00h

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

R/W

R/W Read Only Read Only

15/157

ST7232A

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.

16/157

4 FLASH PROGRAM MEMORY

ST7232A

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 programmed 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 6). They are mapped in the upper part 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.

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.

Figure 6. Memory Map and Sector Address

4K 10K 24K 48K

1000h 3FFFh

7FFFh

9FFFh

BFFFh

D7FFh

DFFFh

EFFFh

FFFFh

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

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ST7232A

FLASH PROGRAM MEMORY (Cont’d)

4.4 ICC Interface

ICC needs a minimum of 4 and up to 6 pins to be connected to the programming tool (see Figure 7). These pins are:

– RESET –V

: device reset

: device power supply ground

Figure 7. Typical ICC Interface

PROGRAMMING TOOL

APPLICATION POWER SUPPLY

(See Note 3)

OSC2

(See caution)

OSC1

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 application RESET circuit in this case. When using a

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 7, Note 3)

ICC CONNECTOR

975 3

10kΩ

ICCSEL/VPP

ICC Cable

RESET

ICCCLK

HE10 CONNECTOR TYPE

246810

ICCDATA

APPLICATION BOARD

ICC CONNECTOR

APPLICATION RESET SOURCE

See Note 2

See Note 1

APPLICATION

I/O

classical RC network with R>1K or a reset management IC with open drain output and pull-up resistor>1K, no additional components are needed. In all cases the user must ensure that no external 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.

Caution: External clock ICC entry mode is mandatory. Pin 9 must be connected to the OSC1 or OSCIN pin of the ST7 and OSC2 must be grounded.

18/157

FLASH PROGRAM MEMORY (Cont’d)

ST7232A

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 downloaded 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 7). 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 example, 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.

Table 4. Flash Control/Status Register Address and Reset Value

Address

(Hex.)

0029h

Label

FCSR

Reset Value00000000

76543210

19/157

ST7232A

5 CENTRAL PROCESSING UNIT

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/hardware interrupts

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 accessed 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-Assembler 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 containing 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

PCL

ACCUMULATOR

X INDEX REGISTER

Y INDEX REGISTER

PROGRAM COUNTER

CONDITION CODE REGISTER

STACK POINTER

X = Undefined Value

20/157

CENTRAL PROCESSING UNIT (Cont’d)

Condition Code Register (CC)

Read/Write Reset Value: 111x1xxx

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.

11I1HI0NZ

1: The result of the last operation is zero.

This bit is accessed by the JREQ and JRNE test The 8-bit Condition Code register contains the interrupt masks and four flags representative of the result of the instruction just executed. This register 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. It is repre-

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

sult 7

bit. 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.

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 the 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.

ST7232A

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ST7232A

CENTRAL PROCESSING UNIT (Cont’d)

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 which is always pointing to the next free location in the stack. It is then decremented after data 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 stored at the first location pointed to by the SP. Then the other registers are stored in the next locations as shown in Figure 9.

– When an interrupt 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

22/157

6 SUPPLY, RESET AND CLOCK MANAGEMENT

ST7232A

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

■ Reset Sequence Manager (RSM)

■ Multi-Oscillator Clock Management (MO)

– 5 Crystal/Ceramic resonator oscillators

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 multiply

Figure 11. Clock, Reset and Supply Block Diagram

OSC2

OSC1

MULTI-

OSCILLATOR

(MO)

OSC

PLL

(option)

SYSTEM INTEGRITY MANAGEMENT

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.

Figure 10. PLL Block Diagram

OSC

PLL x 2

/ 2

OSC2

PLL OPTION BIT

MAIN CLOCK

CONTROLLER

WITH REALTIME

CLOCK (MCC/RTC)

OSC2

CPU

RESET

RESET SEQUENCE

MANAGER

(RSM)

SICSR

WATCHDOG

TIMER (WDG)

WDG

23/157

ST7232A

6.2 MULTI-OSCILLATOR (MO)

The main clock of the ST7 can be generated by two different source types coming from the multioscillator block:

■ an external source

■ 4 crystal or ceramic resonator oscillators

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 5. 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 Section 14.1 on page 145 for more details on

the frequency ranges). In this mode of the multioscillator, 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.

Table 5. ST7 Clock Sources

Hardware Configuration

ST7

OSC1 OSC2

External ClockCrystal/Ceramic Resonators

EXTERNAL

SOURCE

OSC1 OSC2

CAPACITORS

ST7

LOAD

24/157

6.3 RESET SEQUENCE MANAGER (RSM)

ST7232A

6.3.1 Introduction

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

■ External RESET source pulse

■ 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.

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 Electrical Characteristic section 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

WATCHDOG RESET

INTERNAL RESET

25/157

ST7232A

RESET SEQUENCE MANAGER (Cont’d)

The RESET plays a major role in EMS performance. In a noisy environment, it is recommended to follow the guidelines mentioned in the electrical characteristics section.

6.3.3 External Power-On RESET

To start up the microcontroller correctly, the user must ensure by means of an external reset circuit that the reset signal is held low until V the minimum level specified for the selected f frequency.

Figure 14. RESET Sequences

pin is an asynchronous signal which

is over

OSC

A proper reset signal for a slow rising V

supply

can generally be provided by an external RC network connected to the RESET

pin.

6.3.4 Internal Watchdog RESET

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

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

pin acts as an output that is pulled

w(RSTL)out

EXTERNAL RESET SOURCE

RESET PIN

WATCHDOG RESET

RUN

h(RSTL)in

EXTERNAL

RESET

ACTIVE PHASE

WATCHDOG UNDERFLOW

RUN RUN

INTERNAL RESET (256 or 4096 T VECTOR FETCH

WATCHDOG

RESET

ACTIVE PHASE

w(RSTL)out

CPU

)

26/157

6.4 SYSTEM INTEGRITY MANAGEMENT

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

Read/Write Reset Value: 0000 000x (00h)

Bit 0 = WDGRF Watchdog reset flag This bit indicates that the last Reset was generat-

ed by the Watchdog peripheral. It is set by hardware (watchdog reset) and cleared by software

0000000

WDG

(writing zero).

Bits 7:1 = Reserved, must be kept cleared.

ST7232A

27/157

ST7232A

7 INTERRUPTS

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

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 6). The processing flow is shown in Figure 15

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 6. 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 15. Interrupt Processing Flowchart

RESET

RESTORE PC, X, A, CC

FROM STACK

28/157

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

INTERRUPTS (Cont’d)

ST7232A

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 16 describes this decision process.

Figure 16. 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: RESET and TRAP can be considered as having the highest software priority in the 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 15). 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 15.

■ 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 the 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.

■ External Interrupts

External interrupts allow the processor to exit from HALT low power mode. External interrupt 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 set 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.

29/157

ST7232A

INTERRUPTS (Cont’d)

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 while 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 process shown in Figure 16.

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 17. 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 17 and Figure 18 show two different interrupt management modes. The first is called concurrent mode and does not allow an interrupt to be interrupted, unlike the nested mode in

Figure 18. The interrupt hardware priority is given

in this order from the lowest to the highest: MAIN, IT4, IT3, IT2, IT1, IT0. 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 18. Nested Interrupt Management

IT4

IT3

TRAP

IT0

HARDWARE PRIORITY

MAIN

RIM

IT2

IT1

IT4

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