ST72F321BJ9T6

ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 64/44-pin 8-bit MCU with 32 to 60K Flash/ROM, ADC, five timers, SPI, SCI, I2C interface Features ■ ■ ■ ■ ■ 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 retention: 40 years at 85°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 oscillators, 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 on 64-pin devices – 15/9 external interrupt lines (on 4 vectors) Up to 48 I/O Ports – 48/32/24 multifunctional bidirectional I/O lines – 34/22/17 alternate function lines – 16/12/10 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 output compares, external clock input on one timer, PWM and pulse generator modes LQFP64 14 x 14 LQFP64 10 x 10 ■ ■ ■ ■ LQFP32 7x7 LQFP44 10 x 10 – 8-bit PWM Auto-reload timer with: 2 input captures, 4 PWM outputs, output compare and time base interrupt, external clock with event detector 3 Communications Interfaces – SPI synchronous serial interface – SCI asynchronous serial interface – I2C multimaster interface 1 Analog peripheral (low current coupling) – 10-bit ADC with up to 16 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 Table 1. Device Summary Features Program memory bytes RAM (stack) - bytes Operating Voltage Temp. Range Package October 2008 ST72321BAR9/ ST72321BR9/ ST72321BJ9 ST72321BAR7/ ST72321BR7/ ST72321BJ7 ST72321BAR6/ ST72321BR6/ ST72321BJ6/ST72321BK6 FLASH/ROM 60K FLASH/ROM 48K FLASH/ROM 32K 2048 (256) 1536 (256) 1024 (256) 3.8V to 5.5V up to -40°C to +125°C LQFP64 10x10 (AR),LQFP64 14x14 (R), LQFP44 10x10 (J), LQFP32 7x7 (K) Rev 5 1/187 1 Table of Contents 1 DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.2 Asynchronous External RESET pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 26 27 27 27 28 6.4.1 Low Voltage Detector (LVD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.2 Auxiliary Voltage Detector (AVD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.3 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.4 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 29 30 31 32 32 7.2 MASKING AND PROCESSING FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 7.3 INTERRUPTS AND LOW POWER MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 7.4 CONCURRENT & NESTED MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 7.5 INTERRUPT REGISTER DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 7.6 EXTERNAL INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 7.6.1 I/O Port Interrupt Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 7.7 EXTERNAL INTERRUPT CONTROL REGISTER (EICR) . . . . . . . . . . . . . . . . . . . . . . . . . 39 8 POWER SAVING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 8.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 . . . . 41 8.2 SLOW MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 8.3 WAIT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2/187 1 Table of Contents 8.4 ACTIVE-HALT AND HALT MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 8.4.1 ACTIVE-HALT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4.2 HALT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 I/O PORTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 44 46 46 9.2 FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 9.2.1 Input Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.2 Output Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.3 Alternate Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3 I/O PORT IMPLEMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 46 46 49 9.4 LOW POWER MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 9.5 INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 9.5.1 I/O Port Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 10 ON-CHIP PERIPHERALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 10.1 WATCHDOG TIMER (WDG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1.6 Hardware Watchdog Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1.7 Using Halt Mode with the WDG (WDGHALT option) . . . . . . . . . . . . . . . . . . . . . . . 10.1.8 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1.9 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2 MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK AND BEEPER (MCC/RTC) . . 52 52 52 53 55 55 55 55 55 57 10.2.1 Programmable CPU Clock Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2.2 Clock-out Capability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2.3 Real Time Clock Timer (RTC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2.4 Beeper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2.5 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2.7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3 PWM AUTO-RELOAD TIMER (ART) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 57 57 57 58 58 58 60 10.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.2 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.3 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4 16-BIT TIMER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 61 65 69 10.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.4 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.5 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.6 Summary of Timer Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5 SERIAL PERIPHERAL INTERFACE (SPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 69 69 81 81 81 82 88 10.5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 10.5.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 3/187 1 Table of Contents 10.5.3 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5.4 Clock Phase and Clock Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5.5 Error Flags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5.6 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5.7 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5.8 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.6 SERIAL COMMUNICATIONS INTERFACE (SCI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 92 93 95 95 96 99 10.6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 10.6.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 10.6.3 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 10.6.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 10.6.5 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 10.6.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 10.6.7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 10.7 I2C BUS INTERFACE (I2C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 10.7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.3 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.5 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.7 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.8 10-BIT A/D CONVERTER (ADC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 115 115 117 121 121 122 128 10.8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.8.2 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.8.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.8.4 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.8.5 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.8.6 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 INSTRUCTION SET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 CPU ADDRESSING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 128 129 129 129 130 132 132 11.1.1 Inherent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.2 Immediate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.3 Direct . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.4 Indexed (No Offset, Short, Long) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.5 Indirect (Short, Long) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.6 Indirect Indexed (Short, Long) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1.7 Relative mode (Direct, Indirect) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 INSTRUCTION GROUPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 133 133 133 133 134 134 135 12 ELECTRICAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 12.1 PARAMETER CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 12.1.1 Minimum and Maximum values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 12.1.2 Typical values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 12.1.3 Typical curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 12.1.4 Loading capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 12.1.5 Pin input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 . . . 138 12.2 ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 4/187 Table of Contents 12.2.1 Voltage Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.2.2 Current Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.2.3 Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3 OPERATING CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 139 140 140 12.3.1 General Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3.2 Operating Conditions with Low Voltage Detector (LVD) . . . . . . . . . . . . . . . . . . . 12.3.3 Auxiliary Voltage Detector (AVD) Thresholds . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3.4 External Voltage Detector (EVD) Thresholds . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.4 SUPPLY CURRENT CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 141 141 141 142 12.4.1 CURRENT CONSUMPTION .................................... 12.4.2 Supply and Clock Managers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.4.3 On-Chip Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5 CLOCK AND TIMING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 143 144 145 12.5.1 General Timings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5.2 External Clock Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5.3 Crystal and Ceramic Resonator Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5.4 RC Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5.5 PLL Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.6 MEMORY CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 145 146 149 150 151 12.6.1 RAM and Hardware Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 12.6.2 FLASH Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 12.7 EMC CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 12.7.1 Functional EMS (Electro Magnetic Susceptibility) . . . . . . . . . . . . . . . . . . . . . . . . 12.7.2 Electro Magnetic Interference (EMI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.7.3 Absolute Maximum Ratings (Electrical Sensitivity) . . . . . . . . . . . . . . . . . . . . . . . 12.8 I/O PORT PIN CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 153 154 155 12.8.1 General Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 12.8.2 Output Driving Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 12.9 CONTROL PIN CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 12.9.1 Asynchronous RESET Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 12.9.2 ICCSEL/VPP Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 12.10TIMER PERIPHERAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 12.10.1 8-Bit PWM-ART Auto-Reload Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 12.10.2 16-Bit Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 12.11COMMUNICATION INTERFACE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . 162 12.11.1 SPI - Serial Peripheral Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 12.11.2 I2C - Inter IC Control Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 12.1210-BIT ADC CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 12.12.1 Analog Power Supply and Reference Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.12.2 General PCB Design Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.12.3 ADC Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 PACKAGE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1 PACKAGE MECHANICAL DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 168 169 170 170 13.2 THERMAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 13.3 SOLDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 14 ST72321B DEVICE CONFIGURATION AND ORDERING INFORMATION . . . . . . . . . . . . . . 174 5/187 Table of Contents 14.1 FLASH OPTION BYTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 14.2 DEVICE ORDERING INFORMATION AND TRANSFER OF CUSTOMER CODE . . . . . 176 14.3 DEVELOPMENT TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 14.3.1 Starter kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.3.2 Development and debugging tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.3.3 Programming tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.3.4 Socket and Emulator Adapter Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.4 ST7 APPLICATION NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 178 178 179 180 15 KNOWN LIMITATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 15.1 ALL DEVICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 15.1.1 Unexpected Reset Fetch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1.2 External interrupt missed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1.3 Clearing active interrupts outside interrupt routine . . . . . . . . . . . . . . . . . . . . . . . 15.1.4 SCI Wrong Break duration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1.5 16-bit Timer PWM Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1.6 TIMD set simultaneously with OC interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1.7 I2C Multimaster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1.8 Pull-up always active on PE2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1.9 ADC accuracy 32K Flash devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 REVISION HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 6/187 183 183 184 185 185 185 185 185 185 186 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 1 DESCRIPTION The ST72F321B Flash and ST72321B ROM devices are members of the ST7 microcontroller family designed for mid-range 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. The ST7 family architecture offers both power and flexibility to software developers, enabling the design of highly efficient and compact application code. The on-chip peripherals include an A/D converter, a PWM Autoreload timer, 2 general purpose timers, I2C bus, SPI interface and an SCI interface. For power economy, microcontroller can switch dynamically into WAIT, SLOW, ACTIVE-HALT or HALT mode when the application is in idle or stand-by state. Typical applications are consumer, home, office and industrial products. Related Documentation AN1131: Migrating applications from ST72511/ 311/314 to ST72521/321/324 Figure 1. Device Block Diagram 8-BIT CORE ALU RESET VPP TLI VSS VDD EVD PROGRAM MEMORY (32K - 60K Bytes) CONTROL RAM (1024 - 2048 Bytes) LVD AVD WATCHDOG OSC1 OSC2 OSC PORT F PF7:0 (8-bits) TIMER A BEEP ADDRESS AND DATA BUS MCC/RTC/BEEP I2C PORT A PORT B PB7:0 (8-bits) PWM ART PORT C PORT E TIMER B PE7:0 (8-bits) PA7:0 (8-bits) PC7:0 (8-bits) SCI SPI PORT D PD7:0 (8-bits) 10-BIT ADC VAREF VSSA 7/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 2 PIN DESCRIPTION PE3 PE2 PE1 / RDI PE0 / TDO VDD_2 OSC1 OSC2 VSS_2 TLI EVD RESET VPP / ICCSEL PA7 (HS) / SCLI PA6 (HS) / SDAI PA5 (HS) PA4 (HS) Figure 2. 64-Pin LQFP 14x14 and 10x10 Package Pinout (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 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 ei0 44 43 ei2 42 41 40 39 ei3 38 37 36 35 ei1 34 33 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 VSS_1 VDD_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 VSS_0 VDD_0 AIN4 / PD4 AIN5 / PD5 AIN6 / PD6 AIN7 / PD7 VAREF VSSA VDD_3 VSS_3 MCO / AIN8 / PF0 BEEP / (HS) PF1 (HS) PF2 OCMP2_A / AIN9 / PF3 OCMP1_A / AIN10 / PF4 ICAP2_A / AIN11 / PF5 ICAP1_A / (HS) PF6 EXTCLK_A / (HS) PF7 AIN2 / PD2 AIN3 / PD3 64 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 (HS) 20mA high sink capability eix associated external interrupt vector 8/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx PE0 / TDO VDD_2 OSC1 OSC2 VSS_2 RESET VPP / ICCSEL PA7 (HS)/ SCLI PA6 (HS) / SDAI PA5 (HS) PA4 (HS) Figure 3. 44-Pin LQFP Package Pinout 44 43 42 41 40 39 38 37 36 35 34 1 33 2 32 3 31 ei0 ei2 4 30 5 29 ei3 6 28 7 27 8 26 9 25 ei1 10 24 11 23 12 13 14 15 16 17 18 19 20 21 22 VSS_1 VDD_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 AIN5 / PD5 VAREF VSSA MCO / AIN8 / PF0 BEEP / (HS) PF1 (HS) PF2 OCMP1_A / AIN10 / PF4 ICAP1_A / (HS) PF6 EXTCLK_A / (HS) PF7 VDD_0 VSS_0 RDI / PE1 PB0 PB1 PB2 PB3 (HS) PB4 AIN0 / PD0 AIN1 / PD1 AIN2 / PD2 AIN3 / PD3 AIN4 / PD4 (HS) 20mA high sink capability eix associated external interrupt vector 9/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx PD1 / AIN1 PD0 / AIN0 PB4 (HS) PB3 PB0 PE1 / RDI PE0 / TDO VDD_2 Figure 4. 32-Pin LQFP Package Pinout 32 31 30 29 28 27 26 25 24 1 ei3 ei2 23 2 22 3 ei1 21 4 20 5 19 6 18 7 ei0 17 8 9 10 11 12 13 14 15 16 AIN13 / OCMP1_B / PC1 ICAP2_B / (HS) PC2 ICAP1_B / (HS) PC3 ICCDATA / MISO / PC4 AIN14 / MOSI / PC5 ICCCLK / SCK / PC6 AIN15 / SS / PC7 (HS) PA3 VAREF VSSA MCO / AIN8 / PF0 BEEP / (HS) PF1 OCMP1_A / AIN10 / PF4 ICAP1_A / (HS) PF6 EXTCLK_A / (HS) PF7 AIN12 / OCMP2_B / PC0 10/187 OSC1 OSC2 VSS_2 RESET VPP / ICCSEL PA7 (HS) / SCLI PA6 (HS) / SDAI PA4 (HS) (HS) 20mA high sink capability eix associated external interrupt vector ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx PIN DESCRIPTION (Cont’d) For external pin connection guidelines, refer to See “ELECTRICAL CHARACTERISTICS” on page 138. Legend / Abbreviations for Table 2 : Type: I = input, O = output, S = supply Input level: A = Dedicated analog input In/Output level: C = CMOS 0.3VDD/0.7VDD CT= CMOS 0.3VDD/0.7VDD with input trigger TT= 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 1), ana = analog – Output: OD = open drain 2), PP = push-pull Refer to “I/O PORTS” on page 46 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 2. Device Pin Description Port OD PP - - PE4 (HS) I/O CT HS X X X X Port E4 - - PE5 (HS) I/O CT HS X X X X Port E5 3 - - PE6 (HS) I/O CT HS X X X X Port E6 4 - - PE7 (HS) I/O CT HS X X X X Port E7 5 2 6 3 28 PB0/PWM3 - PB1/PWM2 - PB2/PWM1 7 4 8 5 29 PB3/PWM0 9 6 30 PB4 (HS)/ARTCLK 10 - - PB5 / ARTIC1 11 - - PB6 / ARTIC2 - PB7 ana wpu 1 2 Pin Name int float Main Output function (after reset) Output Input Input Type Level LQFP32 LQFP44 LQFP64 Pin n° Alternate function I/O CT X ei2 X X Port B0 PWM Output 3 I/O CT I/O CT X ei2 X X Port B1 PWM Output 2 X ei2 I/O CT I/O CT X HS ei2 X X Port B2 PWM Output 1 X X Port B3 PWM Output 0 X ei3 X X Port B4 PWM-ART External Clock I/O CT X ei3 X X Port B5 PWM-ART Input Capture 1 I/O CT I/O CT X ei3 X X Port B6 PWM-ART Input Capture 2 X X Port B7 I/O CT I/O CT 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 12 - 13 7 31 PD0/AIN0 14 8 32 PD1/AIN1 15 9 - PD2/AIN2 16 10 - PD3/AIN3 I/O CT I/O CT X X X X X Port D3 ADC Analog Input 3 17 11 - PD4/AIN4 I/O CT X X X X X Port D4 ADC Analog Input 4 18 12 - PD5/AIN5 X X X X X Port D5 ADC Analog Input 5 19 - - PD6/AIN6 I/O CT I/O CT X X X X X Port D6 ADC Analog Input 6 20 - - PD7/AIN7 X X X X X Port D7 ADC Analog Input 7 21 13 1 VAREF I/O CT I 22 14 2 VSSA S X ei3 Analog Reference Voltage for ADC Analog Ground Voltage 11/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx Level - VDD_3 S Digital Main Supply Voltage 24 - - VSS_3 S Digital Ground Voltage 25 15 3 PF0/MCO/AIN8 I/O CT 26 16 4 PF1 (HS)/BEEP 27 17 - PF2 (HS) I/O CT I/O CT 28 - - PF3/OCMP2_A/AIN9 I/O CT X X 29 18 5 PF4/OCMP1_A/ AIN10 I/O CT X 30 - - PF5/ICAP2_A/AIN11 I/O CT 31 19 6 PF6 (HS)/ICAP1_A I/O CT 32 20 7 PF7 (HS)/EXTCLK_A I/O CT 33 21 - VDD_0 S Digital Main Supply Voltage 34 22 - VSS_0 S Digital Ground Voltage 35 23 8 PC0/OCMP2_B/ AIN12 I/O CT X X X X X Port C0 Timer B Out- ADC Anaput Compare log 2 Input 12 36 24 9 PC1/OCMP1_B/ AIN13 I/O CT X X X X X Port C1 Timer B Out- ADC Anaput Compare log 1 Input 13 Alternate function PP ana int wpu float Input OD - Output 23 Pin Name Input LQFP32 Main function Output (after reset) LQFP44 Port LQFP64 Type Pin n° ADC Analog Input 8 X X Port F0 Main clock out (fOSC/2) X X Port F1 Beep signal output X X Port F2 X X X Port F3 Timer A Out- ADC Anaput Compare log 2 Input 9 X X X X Port F4 Timer A Out- ADC Anaput Compare log 1 Input 10 X X X X X Port F5 ADC AnaTimer A Input log Capture 2 Input 11 HS X X X X Port F6 Timer A Input Capture 1 HS X X X X Port F7 Timer A External Clock Source X ei1 HS X ei1 HS X X ei1 37 25 10 PC2 (HS)/ICAP2_B I/O CT HS X X X X Port C2 Timer B Input Capture 2 38 26 11 PC3 (HS)/ICAP1_B I/O CT HS X X X X Port C3 Timer B Input Capture 1 39 27 12 PC4/MISO/ICCDATA I/O CT X X X X Port C4 SPI Master In ICC Data / Slave Out Input Data 40 28 13 PC5/MOSI/AIN14 I/O CT X X X X Port C5 SPI Master ADC AnaOut / Slave In log Data Input 14 41 29 14 PC6/SCK/ICCCLK I/O CT X X X X Port C6 SPI Serial Clock 42 30 15 PC7/SS/AIN15 I/O CT X X X X Port C7 SPI Slave Se- ADC Analect (active log low) Input 15 43 - - PA0 ei0 X X Port A0 - - PA1 I/O CT I/O CT X 44 X ei0 X X Port A1 - PA2 I/O CT X ei0 16 PA3 (HS) I/O CT 45 - 46 31 47 32 12/187 - VDD_1 S HS X X X ei0 X X Port A2 X X Port A3 ICC Clock Output Digital Main Supply Voltage ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 49 34 50 35 51 52 VSS_1 17 PA4 (HS) Alternate function PP OD ana int wpu Input Main function Output (after reset) S Digital Ground Voltage I/O CT HS X X X X Port A4 PA5 (HS) I/O CT HS X X X X Port A5 36 18 PA6 (HS)/SDAI I/O CT HS X T Port A6 I2C Data 1) 37 19 PA7 (HS)/SCLI I/O CT HS X T Port A7 I2C Clock 1) - 53 38 20 VPP/ ICCSEL 54 39 21 RESET 55 - - EVD 56 - - TLI 57 40 22 VSS_2 58 41 23 OSC23) 59 Port float LQFP32 - Output LQFP44 33 Type LQFP64 48 Pin Name Input Level Pin n° 42 24 OSC13) 60 43 25 VDD_2 61 44 26 PE0/TDO 62 1 27 PE1/RDI Must be tied low. In flash programming mode, this pin acts as the programming voltage input VPP. See Section 12.9.2 for more details. High voltage must not be applied to ROM devices I I/O CT Top priority non maskable interrupt. External voltage detector I CT X Top level interrupt input pin S Digital Ground Voltage I/O Resonator oscillator inverter output External clock input or Resonator oscillator inverter input I S I/O CT I/O CT 63 - - PE2 I/O CT 64 - - PE3 I/O CT Digital Main Supply Voltage X X X X Port E0 SCI Transmit Data Out X X X X Port E1 SCI Receive Data In X X5) X5) Port E2 X X X Port E3 X 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 VDD are not implemented). See See “I/O PORTS” on page 46. and Section 12.8 I/O PORT PIN CHARACTERISTICS 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 DESCRIPTION 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: – Pads that are not bonded to external pins are forced by hardware in input pull-up configuration after reset. The configuration of these pads must be kept at reset state to avoid added current consumption. 5. Pull-up always activated on PE2 see limitation Section 15.1.8. 6. It is mandatory to connect all available VDD and VREF pins to the supply voltage and all VSS and VSSA pins to ground. 13/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 3 REGISTER & MEMORY MAP 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 2Kbytes of RAM and up to 60Kbytes of user program memory. 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. IMPORTANT: Memory locations marked as “Reserved” must never be accessed. Accessing a reseved area can have unpredictable effects on the device. Related Documentation AN 985: Executing Code in ST7 RAM Figure 5. Memory Map 0000h 007Fh 0080h HW Registers (see Table 3) 087Fh 0880h Reserved 0FFFh 1000h Program Memory (60K, 48K or 32K) FFFFh 14/187 Short Addressing RAM (zero page) 00FFh 0100h RAM (2048, 1536 or 1024 Bytes) FFDFh FFE0h 0080h Interrupt & Reset Vectors (see Table 8) 256 Bytes Stack 01FFh 0200h or 047Fh or 067Fh or 087Fh 1000h 16-bit Addressing RAM 4000h 8000h FFFFh 60 KBytes 48 KBytes 32 KBytes ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx Table 3. Hardware Register Map Register Label Block 0000h 0001h 0002h Port A 2) PADR PADDR PAOR Port A Data Register Port A Data Direction Register Port A Option Register 00h1) 00h 00h R/W R/W R/W 0003h 0004h 0005h 2) PBDR PBDDR PBOR Port B Data Register Port B Data Direction Register Port B Option Register 00h1) 00h 00h R/W R/W R/W PCDR PCDDR PCOR Port C Data Register Port C Data Direction Register Port C Option Register 00h1) 00h 00h R/W R/W R/W Port D 2) PDDR PDDDR PDOR Port D Data Register Port D Data Direction Register Port D Option Register 00h1) 00h 00h R/W R/W R/W 000Ch 000Dh 000Eh Port E 2) PEDR PEDDR PEOR Port E Data Register Port E Data Direction Register Port E Option Register 00h1) 00h 00h R/W R/W2) R/W2) 000Fh 0010h 0011h Port F 2) PFDR PFDDR PFOR Port F Data Register Port F Data Direction Register Port F Option Register 00h1) 00h 00h R/W R/W R/W 0006h 0007h 0008h 0009h 000Ah 000Bh Port B Port C 0012h to 0017h 0018h 0019h 001Ah 001Bh 001Ch 001Dh 001Eh 0024h 0025h 0026h 0027h I 2C I2CCR I2CSR1 I2CSR2 I2CCCR I2COAR1 I2COAR2 I2CDR I2C Control Register I2C Status Register 1 I2C Status Register 2 I2C Clock Control Register I2C Own Address Register 1 I2C Own Address Register2 I2C Data Register 00h 00h 00h 00h 00h 00h 00h R/W Read Only Read Only R/W R/W R/W R/W Reserved Area (2 Bytes) SPI ITC 0028h 0029h Remarks Reserved Area (6 Bytes) 001Fh 0020h 0021h 0022h 0023h Register Name Reset Status Address FLASH SPIDR SPICR SPICSR SPI Data I/O Register SPI Control Register SPI Control/Status Register xxh 0xh 00h R/W R/W R/W ISPR0 ISPR1 ISPR2 ISPR3 Interrupt Software Priority Register 0 Interrupt Software Priority Register 1 Interrupt Software Priority Register 2 Interrupt Software Priority Register 3 FFh FFh FFh FFh R/W R/W R/W R/W EICR External Interrupt Control Register 00h R/W FCSR Flash Control/Status Register 00h R/W 15/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx Address Block 002Ah WATCHDOG 002Bh 002Ch 002Dh MCC Register Label WDGCR Watchdog Control Register SICSR System Integrity Control/Status Register MCCSR MCCBCR Main Clock Control / Status Register Main Clock Controller: Beep Control Register 002Eh to 0030h 0031h 0032h 0033h 0034h 0035h 0036h 0037h 0038h 0039h 003Ah 003Bh 003Ch 003Dh 003Eh 003Fh 0050h 0051h 0052h 0053h 0054h 0055h 0056h 0057h 16/187 Reset Status 7Fh Remarks R/W 000x 000x b R/W 00h 00h R/W R/W Reserved Area (3 Bytes) TIMER A TACR2 TACR1 TACSR TAIC1HR TAIC1LR TAOC1HR TAOC1LR TACHR TACLR TAACHR TAACLR TAIC2HR TAIC2LR TAOC2HR TAOC2LR 0040h 0041h 0042h 0043h 0044h 0045h 0046h 0047h 0048h 0049h 004Ah 004Bh 004Ch 004Dh 004Eh 004Fh Register Name 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 00h 00h xxxx x0xx b xxh xxh 80h 00h FFh FCh FFh FCh xxh 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 Reserved Area (1 Byte) TIMER B SCI 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 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 SCISR SCIDR SCIBRR SCICR1 SCICR2 SCIERPR 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 C0h xxh 00h x000 0000b 00h 00h --00h Read Only R/W R/W R/W R/W R/W SCIETPR R/W ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx Address Block Register Label 0058h to 006Fh 0070h 0071h 0072h 007Bh 007Ch 007Dh Reset Status Remarks Reserved Area (24 Bytes) ADC 0073h 0074h 0075h 0076h 0077h 0078h 0079h 007Ah Register Name PWM ART ADCCSR ADCDRH ADCDRL Control/Status Register Data High Register Data Low Register 00h 00h 00h R/W Read Only Read Only 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 00h 00h 00h 00h 00h 00h 00h 00h R/W R/W R/W R/W R/W R/W R/W R/W R/W Read Only Read Only 007Eh 007Fh 00h 00h 00h Reserved Area (2 Bytes) 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. 17/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 VPP 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. Depending on the overall Flash memory size in the microcontroller device, there are up to three user sectors (see Table 4). 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 4. Sectors available in Flash devices Flash Size (bytes) Available Sectors 4K Sector 0 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. 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. Figure 6. Memory Map and Sector Address 4K 8K 10K 16K 24K 32K 48K 60K 1000h FLASH MEMORY SIZE 3FFFh 7FFFh 9FFFh SECTOR 2 BFFFh D7FFh DFFFh EFFFh FFFFh 18/187 2 Kbytes 8 Kbytes 16 Kbytes 24 Kbytes 40 Kbytes 52 Kbytes 4 Kbytes 4 Kbytes SECTOR 1 SECTOR 0 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx FLASH PROGRAM MEMORY (Cont’d) – – – – ICCCLK: ICC output serial clock pin ICCDATA: ICC input/output serial data pin ICCSEL/VPP: programming voltage OSC1(or OSCIN): main clock input for external source (optional) – VDD: application board power supply (optional, see Figure 7, Note 3) 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: device reset – VSS: device power supply ground Figure 7. Typical ICC Interface PROGRAMMING TOOL ICC CONNECTOR ICC Cable APPLICATION BOARD (See Note 3) ICC CONNECTOR HE10 CONNECTOR TYPE OPTIONAL (See Note 4) 9 7 5 3 1 10 8 6 4 2 APPLICATION RESET SOURCE See Note 2 10kΩ 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 pin. This can lead to conflicts between the programming tool and the application reset circuit if it drives more than 5mA at high level (push pull output or pull-up resistor1K or a reset man- ICCDATA ICCCLK ST7 RESET See Note 1 ICCSEL/VPP OSC1 CL1 OSC2 VDD CL2 VSS APPLICATION POWER SUPPLY 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 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. 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. 19/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 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) 7 0 0 0 0 0 0 0 0 0 This register is reserved for use by Programming Tool software. It controls the Flash programming and erasing operations. Figure 8. Flash Control/Status Register Address and Reset Value Address (Hex.) Register Label 0029h FCSR Reset Value 20/187 7 6 5 4 3 2 1 0 0 0 0 0 0 0 0 0 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 5 CENTRAL PROCESSING UNIT 5.1 INTRODUCTION 5.3 CPU REGISTERS This CPU has a full 8-bit architecture and contains six internal registers allowing efficient 8-bit data manipulation. The six CPU registers shown in Figure 1 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). 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 9. CPU Registers 7 0 ACCUMULATOR RESET VALUE = XXh 7 0 X INDEX REGISTER RESET VALUE = XXh 7 0 Y INDEX REGISTER RESET VALUE = XXh 15 PCH 8 7 PCL 0 PROGRAM COUNTER RESET VALUE = RESET VECTOR @ FFFEh-FFFFh 7 0 1 1 I1 H I0 N Z C CONDITION CODE REGISTER RESET VALUE = 1 1 1 X 1 X X X 15 8 7 0 STACK POINTER RESET VALUE = STACK HIGHER ADDRESS X = Undefined Value 21/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx CENTRAL PROCESSING UNIT (Cont’d) Condition Code Register (CC) Read/Write Reset Value: 111x1xxx Bit 1 = Z Zero. 7 1 0 1 I1 H I0 N Z C 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 between 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 representative of the result sign of the last arithmetic, logical or data manipulation. It’s a copy of the result 7th bit. 0: The result of the last operation is positive or null. 1: The result of the last operation is negative (that is, the most significant bit is a logic 1). This bit is accessed by the JRMI and JRPL instructions. 22/187 This bit is set and cleared by hardware. This bit indicates 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 the current interrupt software priority. Interrupt Software Priority Level 0 (main) Level 1 Level 2 Level 3 (= interrupt disable) I1 1 0 0 1 I0 0 1 0 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. ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx CENTRAL PROCESSING UNIT (Cont’d) Stack Pointer (SP) Read/Write Reset Value: 01 FFh 15 0 8 0 0 0 0 0 0 7 SP7 1 0 SP6 SP5 SP4 SP3 SP2 SP1 SP0 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 2). 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 higher address. 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. 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 instructions. 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 2. – When an interrupt is received, the SP is decremented 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. Figure 10. Stack Manipulation Example CALL Subroutine PUSH Y Interrupt Event POP Y RET or RSP IRET @ 0100h SP SP CC A SP CC A X X X PCH PCH PCH PCL PCL PCL PCH PCH PCH PCH PCH PCL PCL PCL PCL PCL SP @ 01FFh Y CC A SP SP Stack Higher Address = 01FFh Stack Lower Address = 0100h 23/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 6 SUPPLY, RESET AND CLOCK MANAGEMENT 6.1 PHASE LOCKED LOOP 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 12. For more details, refer to dedicated parametric section. If the clock frequency input to the PLL is in the range 2 to 4 MHz, the PLL can be used to multiply the frequency by two to obtain an fOSC2 of 4 to 8 MHz. The PLL is enabled by option byte. If the PLL is disabled, then fOSC2 = fOSC/2. Caution: The PLL is not recommended for applications where timing accuracy is required. See “PLL Characteristics” on page 150. 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. PLL Block Diagram PLL x 2 0 /2 1 fOSC fOSC2 PLL OPTION BIT Figure 12. Clock, Reset and Supply Block Diagram OSC2 MULTI- OSC1 fOSC2 fOSC OSCILLATOR (MO) PLL (option) MAIN CLOCK fCPU CONTROLLER WITH REALTIME CLOCK (MCC/RTC) SYSTEM INTEGRITY MANAGEMENT RESET SEQUENCE RESET MANAGER (RSM) WATCHDOG AVD Interrupt Request SICSR AVD AVD AVD LVD S IE F RF TIMER (WDG) 0 0 0 LOW VOLTAGE VSS DETECTOR VDD (LVD) 0 EVD 24/187 AUXILIARY VOLTAGE DETECTOR 1 (AVD) WDG RF ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 6.2 MULTI-OSCILLATOR (MO) Table 5. ST7 Clock Sources External Clock Hardware Configuration Crystal/Ceramic Resonators 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 174 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. Internal RC Oscillator The main clock of the ST7 can be generated by three different source types coming from 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 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 fOSC clock frequency 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. ST7 OSC1 OSC2 EXTERNAL SOURCE ST7 OSC1 CL1 OSC2 LOAD CAPACITORS CL2 ST7 OSC1 OSC2 25/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 6.3 RESET SEQUENCE MANAGER (RSM) 6.3.1 Introduction The reset sequence manager includes three RESET sources as shown in Figure 14: ■ External RESET source pulse ■ Internal LVD RESET (Low Voltage Detection) ■ Internal WATCHDOG RESET These sources act on the RESET pin and it is always kept low during the delay phase. The RESET service routine vector is fixed at addresses FFFEh-FFFFh in the ST7 memory map. The basic RESET sequence consists of 3 phases as shown in Figure 13: ■ 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 174). The RESET vector fetch phase duration is 2 clock cycles. Figure 13. RESET Sequence Phases RESET Active Phase INTERNAL RESET 256 or 4096 CLOCK CYCLES FETCH VECTOR Caution: When the ST7 is unprogrammed or fully erased, the Flash is blank and the RESET vector is not programmed. For this reason, it is recommended to keep the RESET pin in low state until programming mode is entered, in order to avoid unwanted behavior. 6.3.2 Asynchronous External RESET pin The RESET pin is both an input and an open-drain output with integrated RON weak pull-up resistor. 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 158 for more details. A RESET signal originating from an external source must have a duration of at least th(RSTL)in in order to be recognized (see Figure 15). This detection is asynchronous and therefore the MCU can enter reset state even in HALT mode. Figure 14. Reset Block Diagram VDD RON RESET INTERNAL RESET Filter PULSE GENERATOR 26/187 WATCHDOG RESET LVD RESET ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 pulse is shorter than tw(RSTL)out (see short ext. Reset in Figure 15), the signal on the RESET pin may be stretched. Otherwise the delay will not be applied (see long ext. Reset in Figure 15). Starting from the external RESET pulse recognition, the device RESET pin acts as an output that is pulled low during at least tw(RSTL)out. 6.3.3 External Power-On RESET If the LVD is disabled by option byte, 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 VDD is over the minimum level specified for the selected fOSC frequency. (see “OPERATING CONDITIONS” on page 140) A proper reset signal for a slow rising VDD supply 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 pin acts as an output that is pulled low when VDD 7-bit > 6-bit > 5-bit > 4-bit fPWM Min Max ~0.244 kHz ~0.244 kHz ~0.488 kHz ~0.977 kHz ~1.953 kHz 31.25 kHz 62.5 kHz 125 kHz 250 kHz 500 kHz 65/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx ON-CHIP PERIPHERALS (Cont’d) PWM CONTROL REGISTER (PWMCR) Read/Write Reset Value: 0000 0000 (00h) DUTY CYCLE REGISTERS (PWMDCRx) Read/Write Reset Value: 0000 0000 (00h) 7 OE3 OE2 OE1 OE0 OP3 OP2 OP1 0 7 OP0 DC7 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 output signals. PWMx output level OPx Counter OCRx 1 0 0 1 0 1 Note: When an OPx bit is modified, the PWMx output signal polarity is immediately reversed. 66/187 0 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. ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx ON-CHIP PERIPHERALS (Cont’d) INPUT CAPTURE CONTROL / STATUS REGISTER (ARTICCSR) Read/Write Reset Value: 0000 0000 (00h) INPUT CAPTURE REGISTERS (ARTICRx) Read only Reset Value: 0000 0000 (00h) 7 7 IC7 0 0 0 0 CS2 CS1 CIE2 CIE1 CF2 IC6 IC5 IC4 IC3 IC2 IC1 IC0 CF1 Bit 7:6 = Reserved, always read as 0. Bit 5:4 = CS[2:1] Capture Sensitivity These bits are set and cleared by software. They determine the trigger event polarity on the corresponding input capture channel. 0: Falling edge triggers capture on channel x. 1: Rising edge triggers capture on channel x. Bit 7:0 = IC[7:0] Input Capture Data These read only bits are set and cleared by hardware. An ARTICRx register contains the 8-bit auto-reload counter value transferred by the input capture channel x event. 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 occurred on channel x. 67/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx PWM AUTO-RELOAD TIMER (Cont’d) Table 16. PWM Auto-Reload Timer Register Map and Reset Values Address (Hex.) 0073h 0074h 0075h 0076h 0077h 0078h 0079h 007Ah 007Bh 007Ch 007Dh 68/187 Register 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 7 6 5 4 3 2 1 0 DC7 0 DC6 0 DC5 0 DC4 0 DC3 0 DC2 0 DC1 0 DC0 0 DC7 0 DC6 0 DC5 0 DC4 0 DC3 0 DC2 0 DC1 0 DC0 0 DC7 0 DC6 0 DC5 0 DC4 0 DC3 0 DC2 0 DC1 0 DC0 0 DC7 0 DC6 0 DC5 0 DC4 0 DC3 0 DC2 0 DC1 0 DC0 0 OE3 0 OE2 0 OE1 0 OE0 0 OP3 0 OP2 0 OP1 0 OP0 0 EXCL 0 CC2 0 CC1 0 CC0 0 TCE 0 FCRL 0 RIE 0 OVF 0 CA7 0 CA6 0 CA5 0 CA4 0 CA3 0 CA2 0 CA1 0 CA0 0 AR7 0 AR6 0 AR5 0 AR4 0 AR3 0 AR2 0 AR1 0 AR0 0 0 0 CS2 0 CS1 0 CIE2 0 CIE1 0 CF2 0 CF1 0 IC7 0 IC6 0 IC5 0 IC4 0 IC3 0 IC2 0 IC1 0 IC0 0 IC7 0 IC6 0 IC5 0 IC4 0 IC3 0 IC2 0 IC1 0 IC0 0 ARTICCSR Reset Value ARTICR1 Reset Value ARTICR2 Reset Value ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 clock frequencies are not modified. This description covers one or two 16-bit timers. 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: fCPU divided by 2, 4 or 8 ■ Overflow status flag and maskable interrupt ■ External clock input (must be at least four times slower than the CPU clock speed) with the choice 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 and low. Counter Register (CR): – Counter High Register (CHR) is the most significant byte (MS Byte). – Counter Low Register (CLR) is the least significant byte (LS Byte). Alternate Counter Register (ACR) – Alternate Counter High Register (ACHR) is 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 timer). 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 1. The value in the counter register repeats every 131072, 262144 or 524288 CPU clock cycles depending on the CC[1:0] bits. The timer frequency can be fCPU/2, fCPU/4, fCPU/8 or an external frequency. The Block Diagram is shown in Figure 1. *Note: Some timer pins may not be available (not bonded) in some ST7 devices. Refer to the device pin out description. 69/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) Figure 43. Timer Block Diagram ST7 INTERNAL BUS fCPU MCU-PERIPHERAL INTERFACE 8 low 8 8 8 low 8 high 8 low 8 high EXEDG 8 low high 8 high 8-bit buffer low 8 high 16 1/2 1/4 1/8 OUTPUT COMPARE REGISTER 2 OUTPUT COMPARE REGISTER 1 COUNTER REGISTER ALTERNATE COUNTER REGISTER EXTCLK pin INPUT CAPTURE REGISTER 1 INPUT CAPTURE REGISTER 2 16 16 16 CC[1:0] TIMER INTERNAL BUS 16 16 OVERFLOW DETECT CIRCUIT OUTPUT COMPARE CIRCUIT 6 ICF1 OCF1 TOF ICF2 OCF2 TIMD 0 EDGE DETECT CIRCUIT1 ICAP1 pin EDGE DETECT CIRCUIT2 ICAP2 pin LATCH1 OCMP1 pin LATCH2 OCMP2 pin 0 (Control/Status Register) CSR ICIE OCIE TOIE FOLV2 FOLV1 OLVL2 IEDG1 OLVL1 (Control Register 1) CR1 OC1E OC2E OPM PWM CC1 CC0 IEDG2 EXEDG (Control Register 2) CR2 (See note) TIMER INTERRUPT 70/187 Note: If IC, OC and TO interrupt requests have separate vectors then the last OR is not present (See device Interrupt Vector Table) ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) 16-bit read sequence: (from either the Counter Register or the Alternate Counter Register). Beginning of the sequence At t0 Read MS Byte LS Byte is buffered Other instructions Read At t0 +Δt LS Byte Returns the buffered LS Byte value at t0 Sequence completed The user must read the MS Byte first, then the 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 (input 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. 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. 71/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) Figure 44. Counter Timing Diagram, Internal Clock Divided by 2 CPU CLOCK INTERNAL RESET TIMER CLOCK COUNTER REGISTER FFFD FFFE FFFF 0000 0001 0002 0003 TIMER OVERFLOW FLAG (TOF) Figure 45. Counter Timing Diagram, Internal Clock Divided by 4 CPU CLOCK INTERNAL RESET TIMER CLOCK COUNTER REGISTER FFFC FFFD 0000 0001 TIMER OVERFLOW FLAG (TOF) Figure 46. Counter Timing Diagram, Internal Clock Divided By 8 CPU CLOCK INTERNAL RESET TIMER CLOCK COUNTER REGISTER FFFC FFFD 0000 TIMER OVERFLOW FLAG (TOF) Note: The MCU is in reset state when the internal reset signal is high, when it is low the MCU is running. 72/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) 10.4.3.3 Input Capture In this section, the index, i, may be 1 or 2 because there are two 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). ICiR MS Byte ICiHR LS Byte 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: (fCPU/CC[1:0]). Procedure: To use the input capture function select the following in the CR2 register: – Select the timer clock (CC[1:0]) (see Table 1). – 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 pullup without interrupt if this configuration is available). 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 6). – A timer interrupt is generated if the ICIE bit is set and the I bit is cleared in the CC register. Otherwise, the interrupt remains pending until both conditions become true. Clearing the Input Capture interrupt request (that is, 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 two input capture functions can be used together even if the timer also uses the two output compare functions. 4. In One Pulse mode and PWM mode only Input Capture 2 can be used. 5. The alternate inputs (ICAP1 and ICAP2) are always directly connected to the 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). 73/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) Figure 47. Input Capture Block Diagram ICAP1 pin ICAP2 pin (Control Register 1) CR1 EDGE DETECT CIRCUIT2 EDGE DETECT CIRCUIT1 ICIE IEDG1 (Status Register) SR IC2R Register IC1R Register ICF1 ICF2 0 16-BIT FREE RUNNING COUNTER CC1 CC0 IEDG2 Figure 48. Input Capture Timing Diagram TIMER CLOCK FF01 FF02 FF03 ICAPi PIN ICAPi FLAG ICAPi REGISTER Note: The rising edge is the active edge. 74/187 0 (Control Register 2) CR2 16-BIT COUNTER REGISTER 0 FF03 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) 10.4.3.4 Output Compare In this section, the index, i, may be 1 or 2 because there are two output compare functions in the 16bit 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 output 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 cycle. OCiR MS Byte OCiHR LS Byte OCiLR These registers are readable and writable and are not affected by the timer hardware. A reset event changes the OCiR value to 8000h. Timing resolution is one count of the free running counter: (fCPU/CC[1:0]). 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 timer clock (CC[1:0]) (see Table 1). 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 OCiR register and CR register: – OCFi bit is set. – 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 OCiR register value required for a specific timing application can be calculated using the following formula: Δ OCiR = Δt * fCPU PRESC Where: Δt = Output compare period (in seconds) fCPU = CPU clock frequency (in hertz) = Timer prescaler factor (2, 4 or 8 dePRESC pending on CC[1:0] bits, see Table 1) If the timer clock is an external clock, the formula is: Δ OCiR = Δt * fEXT Where: Δt = Output compare period (in seconds) fEXT = External timer clock frequency (in hertz) Clearing the output compare interrupt request (that is, 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 register. The following procedure is recommended to prevent the OCFi bit from being set between the time it is read and the write to the OCiR register: – 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). 75/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) Notes: 1. After a processor write cycle to the OCiHR register, 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. In both internal and external clock modes, OCFi and OCMPi are set while the counter value equals the OCiR register value (see Figure 8 for an example with fCPU/2 and Figure 9 for an example with fCPU/4). This behavior is the same in OPM or PWM mode. 4. The output compare functions can 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 OCiR 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. 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 49. Output Compare Block Diagram 16 BIT FREE RUNNING COUNTER OC1E OC2E CC1 CC0 (Control Register 2) CR2 16-bit (Control Register 1) CR1 OUTPUT COMPARE CIRCUIT 16-bit OCIE FOLV2 FOLV1 OLVL2 OLVL1 16-bit Latch 2 OC1R Register OCF1 OCF2 0 0 0 OC2R Register (Status Register) SR 76/187 Latch 1 OCMP1 Pin OCMP2 Pin ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) Figure 50. Output Compare Timing Diagram, fTIMER = fCPU/2 INTERNAL CPU CLOCK TIMER CLOCK COUNTER REGISTER 2ECF 2ED0 OUTPUT COMPARE REGISTER i (OCRi) 2ED1 2ED2 2ED3 2ED4 2ED3 OUTPUT COMPARE FLAG i (OCFi) OCMPi PIN (OLVLi = 1) Figure 51. Output Compare Timing Diagram, fTIMER = fCPU/4 INTERNAL CPU CLOCK TIMER CLOCK COUNTER REGISTER OUTPUT COMPARE REGISTER i (OCRi) 2ECF 2ED0 2ED1 2ED2 2ED3 2ED4 2ED3 OUTPUT COMPARE FLAG i (OCFi) OCMPi PIN (OLVLi = 1) 77/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 applied to the OCMP1 pin after the pulse. – Using the OLVL2 bit, select the level to be applied to the OCMP1 pin during the pulse. – Select the edge of the active transition on the ICAP1 pin with the IEDG1 bit (the ICAP1 pin must be configured as floating input). 3. Select the following in the CR2 register: – Set the OC1E bit, the OCMP1 pin is then dedicated to the Output Compare 1 function. – Set the OPM bit. – Select the timer clock CC[1:0] (see Table 1). 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 counter 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. 78/187 Clearing the Input Capture interrupt request (that is, 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 = t * fCPU -5 PRESC Where: t = Pulse period (in seconds) fCPU = CPU clock frequency (in hertz) PRESC = Timer prescaler factor (2, 4 or 8 depending on the CC[1:0] bits, see Table 1) If the timer clock is an external clock the formula is: OCiR = t * fEXT -5 Where: t = Pulse period (in seconds) fEXT = External timer clock frequency (in hertz) When the value of the counter is equal to the value of the contents of the OC1R register, the OLVL1 bit is output on the OCMP1 pin, (See Figure 10). Notes: 1. The OCF1 bit cannot be set by hardware 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 perform input capture. 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 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. ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) Figure 52. One Pulse Mode Timing Example COUNTER 2ED3 01F8 IC1R 01F8 FFFC FFFD FFFE 2ED0 2ED1 2ED2 FFFC FFFD 2ED3 ICAP1 OLVL2 OCMP1 OLVL1 OLVL2 compare1 Note: IEDG1 = 1, OC1R = 2ED0h, OLVL1 = 0, OLVL2 = 1 Figure 53. Pulse Width Modulation Mode Timing Example with 2 Output Compare Functions 2ED0 2ED1 2ED2 COUNTER 34E2 FFFC FFFD FFFE OLVL2 OCMP1 compare2 OLVL1 compare1 34E2 FFFC OLVL2 compare2 Note: OC1R = 2ED0h, OC2R = 34E2, OLVL1 = 0, OLVL2 = 1 Note: On timers with only one Output Compare register, a fixed frequency PWM signal can be generated using the output compare and the counter overflow to define the pulse length. 79/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 implemented 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 applied to the OCMP1 pin after a successful comparison with the OC1R register. – Using the OLVL2 bit, select the level to be applied 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 dedicated to the output compare 1 function. – Set the PWM bit. – Select the timer clock (CC[1:0]) (see Table 1). Pulse Width Modulation cycle When Counter = OC1R When Counter = OC2R OCMP1 = OLVL1 OCMP1 = OLVL2 Counter is reset to FFFCh ICF1 bit is set 80/187 If OLVL1 = 1 and OLVL2 = 0 the length of the positive pulse is the difference between the OC2R and OC1R registers. If OLVL1 = OLVL2 a continuous signal will be seen on the OCMP1 pin. The OCiR register value required for a specific timing application can be calculated using the following formula: OCiR Value = t * fCPU -5 PRESC Where: t = Signal or pulse period (in seconds) fCPU = CPU clock frequency (in hertz) PRESC = Timer prescaler factor (2, 4 or 8 depending on CC[1:0] bits, see Table 1) If the timer clock is an external clock the formula is: OCiR = t * fEXT -5 Where: t = Signal or pulse period (in seconds) fEXT = External timer clock frequency (in hertz) The Output Compare 2 event causes the counter to be initialized to FFFCh (See Figure 11) Notes: 1. After a write instruction to the OCiHR register, the output compare function is inhibited until the OCiLR register is also written. 2. The OCF1 and OCF2 bits cannot be set by hardware in PWM mode therefore the Output Compare interrupt is inhibited. 3. The ICF1 bit is set by hardware when the counter reaches the OC2R value and can produce a timer interrupt if the ICIE bit is set and the I bit is cleared. 4. In PWM mode the ICAP1 pin can not be used 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. 5. When the Pulse Width Modulation (PWM) and One Pulse mode (OPM) bits are both set, the PWM mode is the only active one. ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) 10.4.4 Low Power Modes Mode WAIT HALT Description 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. 10.4.5 Interrupts Event Flag Interrupt Event Input Capture 1 event/Counter reset in PWM mode Input Capture 2 event Output Compare 1 event (not available in PWM mode) Output Compare 2 event (not available in PWM mode) Timer Overflow event ICF1 ICF2 OCF1 OCF2 TOF Enable Control Bit Exit from Wait Exit from Halt Yes No ICIE OCIE TOIE Note: The 16-bit Timer interrupt events are connected to the same interrupt vector (see Interrupts chapter). These events generate an interrupt 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) Output Compare (1 and/or 2) One Pulse Mode PWM Mode Input Capture 1 TIMER RESOURCES Input Capture 2 Output Compare 1 Output Compare 2 Yes Yes Yes Yes No Not Recommended1) Not Recommended3) No Partially 2) No 1) See note 4 in Section 0.1.3.5 One Pulse Mode 2) See note 5 in Section 0.1.3.5 One Pulse Mode 3) See note 4 in Section 0.1.3.6 Pulse Width Modulation Mode 81/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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. CONTROL REGISTER 1 (CR1) Read/Write Reset Value: 0000 0000 (00h) 7 0 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. 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. ICIE OCIE TOIE FOLV2 FOLV1 OLVL2 IEDG1 OLVL1 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. 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. 82/187 Bit 2 = OLVL2 Output Level 2. 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 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. ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) CONTROL REGISTER 2 (CR2) Read/Write Reset Value: 0000 0000 (00h) 7 0 OC1E OC2E OPM PWM CC1 CC0 IEDG2 EXEDG 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 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 3, 2 = CC[1:0] Clock Control. The timer clock mode depends on these bits: Table 17. Clock Control Bits Timer Clock fCPU / 4 fCPU / 2 fCPU / 8 External Clock (where available) CC1 0 1 CC0 0 1 0 1 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. 83/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) CONTROL/STATUS REGISTER (CSR) Read/Write (bits 7:3 read only) Reset Value: xxxx x0xx (xxh) Note: Reading or writing the ACLR register does not clear TOF. 7 ICF1 0 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. 84/187 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 prescaler and counter and 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. ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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. 7 0 7 0 MSB LSB 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). 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. 7 0 7 0 MSB LSB MSB LSB 85/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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. 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. 7 0 7 0 MSB LSB 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. 7 0 MSB LSB COUNTER HIGH REGISTER (CHR) Read Only Reset Value: 1111 1111 (FFh) This is an 8-bit register that contains the high part of the counter value. 7 0 MSB LSB COUNTER LOW REGISTER (CLR) 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. 7 0 MSB LSB 86/187 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 after an access to CSR register does not clear the TOF bit in the CSR register. 7 0 MSB LSB INPUT CAPTURE 2 HIGH REGISTER (IC2HR) 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 2 event). 7 0 MSB LSB INPUT CAPTURE 2 LOW REGISTER (IC2LR) 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 2 event). 7 0 MSB LSB ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 16-BIT TIMER (Cont’d) Table 18. 16-Bit Timer Register Map and Reset Values Address (Hex.) Register Label 7 6 5 4 3 2 1 0 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 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 ICIE 0 OC1E 0 ICF1 x MSB x MSB x MSB 1 MSB 0 MSB 1 MSB 0 MSB 1 MSB 1 MSB 1 MSB 1 MSB x MSB x OCIE 0 OC2E 0 OCF1 x TOIE 0 OPM 0 TOF x FOLV2 0 PWM 0 ICF2 x FOLV1 0 CC1 0 OCF2 x OLVL2 0 CC0 0 TIMD 0 IEDG1 0 IEDG2 0 x x x x x x x x x x x x x 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 0 x x x x x x x x x x x x OLVL1 0 EXEDG 0 x LSB x LSB x LSB 0 LSB 0 LSB 0 LSB 0 LSB 1 LSB 0 LSB 1 LSB 0 LSB x LSB x 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 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 87/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 10.5 SERIAL PERIPHERAL INTERFACE (SPI) 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 (fCPU/4 max.) ■ fCPU/2 max. slave mode frequency (see note) ■ SS Management by software or hardware ■ Programmable clock polarity and phase ■ End of transfer interrupt flag ■ Write collision, Master Mode Fault and Overrun flags Note: In slave mode, continuous transmission is not possible at maximum frequency due to the software overhead for clearing status flags and to initiate the next transmission sequence. 10.5.3 General Description Figure 54 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 and input by SPI slaves Figure 54. Serial Peripheral Interface Block Diagram Data/Address Bus SPIDR Read Interrupt request Read Buffer MOSI MISO 8-Bit Shift Register SPICSR 7 SPIF WCOL OVR MODF SOD bit SS SPI STATE CONTROL 7 SPIE MASTER CONTROL SERIAL CLOCK GENERATOR 88/187 SOD SSM SSI Write SCK SS 0 0 1 0 SPICR 0 SPE SPR2 MSTR CPOL CPHA SPR1 SPR0 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 inputs can be driven by standard 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 55. 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). 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 pins 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 58) but master and slave must be programmed with the same timing mode. Figure 55. Single Master/ Single Slave Application SLAVE MASTER MSBit LSBit 8-BIT SHIFT REGISTER SPI CLOCK GENERATOR MSBit MISO MISO MOSI MOSI SCK SS LSBit 8-BIT SHIFT REGISTER SCK +5V SS Not used if SS is managed by software 89/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 57) In software management, the external SS pin is free for other application uses and the internal 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 In Slave Mode: There are two cases depending on the data/clock timing relationship (see Figure 56): 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 pin either can be tied to VSS, or made free for standard I/O by managing 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 slave writes to the shift register (see Section 10.5.5.3). Figure 56. Generic SS Timing Diagram MOSI/MISO Byte 1 Byte 2 Master SS Slave SS (if CPHA=0) Slave SS (if CPHA=1) Figure 57. Hardware/Software Slave Select Management SSM bit 90/187 SSI bit 1 SS external pin 0 SS internal Byte 3 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 (MSTR 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 clock phase by configuring the CPOL and CPHA bits. Figure 58 shows the four possible configurations. Note: The 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 tie the SS pin high for 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 the 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. 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 58). Note: The slave must have the same CPOL and CPHA settings as the master. – Manage the SS pin as described in Section 10.5.3.2 and Figure 56. If CPHA=1 SS must be held low continuously. If CPHA=0 SS must 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 slave device 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). 91/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 58). 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 58, 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. Figure 58. Data Clock Timing Diagram CPHA =1 SCK (CPOL = 1) SCK (CPOL = 0) MISO (from master) MOSI (from slave) MSBit Bit 6 Bit 5 Bit 4 Bit3 Bit 2 Bit 1 LSBit MSBit Bit 6 Bit 5 Bit 4 Bit3 Bit 2 Bit 1 LSBit SS (to slave) CAPTURE STROBE CPHA =0 SCK (CPOL = 1) SCK (CPOL = 0) MISO (from master) MOSI (from slave) MSBit MSBit Bit 6 Bit 5 Bit 4 Bit3 Bit 2 Bit 1 LSBit Bit 6 Bit 5 Bit 4 Bit3 Bit 2 Bit 1 LSBit SS (to slave) CAPTURE STROBE Note: This figure should not be used as a replacement for parametric information. Refer to the Electrical Characteristics chapter. 92/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 pin pulled low. When a Master mode fault occurs: – The MODF bit is set and an SPI interrupt request is generated if the SPIE bit is set. – The SPE bit is reset. This blocks all output from the device and disables the SPI peripheral. – The MSTR bit is reset, thus forcing the device into slave mode. Clearing the MODF bit is done through a software sequence: 1. A read access to the SPICSR register while the MODF bit is set. 2. A write to the SPICR register. Notes: To avoid any conflicts in an application with multiple slaves, the SS pin must be pulled 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 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 59). Figure 59. Clearing the WCOL bit (Write Collision Flag) Software Sequence Clearing sequence after SPIF = 1 (end of a data byte transfer) 1st Step Read SPICSR RESULT 2nd Step Read SPIDR SPIF =0 WCOL=0 Clearing sequence before SPIF = 1 (during a data byte transfer) 1st Step Read SPICSR RESULT 2nd Step Read SPIDR WCOL=0 Note: Writing to the SPIDR register instead of reading it does not reset the WCOL bit 93/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 60). The master device selects the individual slave devices by using four pins of a parallel port to control the four SS pins of the slave devices. The SS pins are pulled high during reset since the master device ports will be forced to be inputs at that time, thus disabling the slave devices. 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. Figure 60. Single Master / Multiple Slave Configuration SS SCK Slave MCU Slave MCU MOSI MISO MOSI MISO SCK Master MCU 5V 94/187 SS Ports MOSI MISO SS SS SCK SS SCK Slave MCU SCK Slave MCU MOSI MISO MOSI MISO ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL PERIPHERAL INTERFACE (Cont’d) 10.5.6 Low Power Modes Mode WAIT HALT Description 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 10.5.6.1 Using the SPI to wakeup the MCU from 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. SPI End of Transfer Event Master Mode Fault Event Overrun Error Event Flag Enable Control Bit SPIF MODF OVR SPIE Exit from Wait Exit from Halt Yes Yes Yes No Yes No 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 95/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL PERIPHERAL INTERFACE (Cont’d) 10.5.8 Register Description CONTROL REGISTER (SPICR) Read/Write Reset Value: 0000 xxxx (0xh) 7 SPIE 0 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 19 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 functions of the MISO and MOSI pins are reversed. 96/187 Bit 3 = CPOL Clock Polarity. This bit is set and cleared by software. This 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 the baud rate of the SPI serial clock SCK output by the SPI in master mode. Note: These 2 bits have no effect in slave mode. Table 19. SPI Master mode SCK Frequency Serial Clock SPR2 SPR1 SPR0 fCPU/4 1 0 0 fCPU/8 0 0 0 fCPU/16 0 0 1 fCPU/32 1 1 0 fCPU/64 0 1 0 fCPU/128 0 1 1 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL PERIPHERAL INTERFACE (Cont’d) CONTROL/STATUS REGISTER (SPICSR) Read/Write (some bits Read Only) Reset Value: 0000 0000 (00h) 7 SPIF Bit 3 = Reserved, must be kept cleared. 0 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 has been cleared. 1: Data transfer between the device and an external 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 59). 0: No write collision occurred 1: A write collision has been detected 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 pin and uses the SSI bit value instead. See Section 10.5.3.2 Slave Select Management. 0: Hardware management (SS managed by external pin) 1: Software management (internal SS signal controlled by SSI bit. External SS pin free for general-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 slave select signal when the SSM bit is set. 0 : Slave selected 1 : Slave deselected DATA I/O REGISTER (SPIDR) Read/Write Reset Value: Undefined 7 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 register 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 D7 0 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 54). 97/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL PERIPHERAL INTERFACE (Cont’d) Table 20. SPI Register Map and Reset Values Address (Hex.) 0021h 0022h 0023h 98/187 Register Label 7 6 5 4 3 2 1 0 SPIDR Reset Value SPICR Reset Value SPICSR Reset Value MSB x SPIE 0 SPIF 0 x SPE 0 WCOL 0 x SPR2 0 OVR 0 x MSTR 0 MODF 0 x CPOL x x CPHA x SOD 0 x SPR1 x SSM 0 LSB x SPR0 x SSI 0 0 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 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 configurations ■ 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 2.): – TDO: Transmit Data Output. When the transmitter 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 recovery 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-standard oscillator frequencies 99/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) Figure 61. SCI Block Diagram Write Read (DATA REGISTER) DR Received Data Register (RDR) Transmit Data Register (TDR) TDO Received Shift Register Transmit Shift Register RDI CR1 R8 TRANSMIT WAKE UP CONTROL UNIT T8 SCID M WAKE PCE PS PIE RECEIVER CLOCK RECEIVER CONTROL CR2 SR TIE TCIE RIE ILIE TE RE RWU SBK TDRE TC RDRF IDLE OR NF FE SCI INTERRUPT CONTROL TRANSMITTER CLOCK TRANSMITTER RATE fCPU CONTROL /16 /PR BRR SCP1 SCP0 SCT2 SCT1 SCT0 SCR2 SCR1SCR0 RECEIVER RATE CONTROL CONVENTIONAL BAUD RATE GENERATOR 100/187 PE ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) 10.6.4 Functional Description The block diagram of the Serial Control Interface, is shown in Figure 1. It contains six dedicated registers: – Two control registers (SCICR1 & SCICR2) – A status register (SCISR) – A baud rate register (SCIBRR) – An extended prescaler receiver register (SCIERPR) – An extended prescaler transmitter register (SCIETPR) Refer to the register descriptions in Section 0.1.7 for the definitions of each bit. 10.6.4.1 Serial Data Format Word length may be selected as being either 8 or 9 bits by programming the M bit in the SCICR1 register (see Figure 1.). The TDO pin is in low state during the start bit. The TDO pin is in high state during the stop bit. An Idle character is interpreted as an entire frame of “1”s followed by the start bit of the next frame which contains data. A Break character is interpreted on receiving “0”s for some multiple of the frame period. At the end of the last break frame the transmitter inserts an extra “1” bit to acknowledge the start bit. Transmission and reception are driven by their own baud rate generator. Figure 62. Word Length Programming 9-bit Word length (M bit is set) Possible Parity Bit Data Frame Start Bit Bit0 Bit2 Bit1 Bit3 Bit4 Bit5 Bit6 Start Bit Break Frame Extra ‘1’ Possible Parity Bit Data Frame Bit0 Bit8 Next Stop Start Bit Bit Idle Frame 8-bit Word length (M bit is reset) Start Bit Bit7 Next Data Frame Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 Start Bit Next Data Frame Stop Bit Next Start Bit Idle Frame Start Bit Break Frame Extra Start Bit ‘1’ 101/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) 10.6.4.2 Transmitter The transmitter can send data words of either 8 or 9 bits depending on the M bit status. When the M bit is set, word length is 9 bits and the 9th bit (the MSB) has to be stored in the T8 bit in the SCICR1 register. Character Transmission During an SCI transmission, data shifts out least significant bit first on the TDO pin. In this mode, the SCIDR register consists of a buffer (TDR) between the internal bus and the transmit shift register (see Figure 1.). Procedure – Select the M bit to define the word length. – Select the desired baud rate using the SCIBRR and the SCIETPR registers. – Set the TE bit to assign the TDO pin to the alternate function and to send a idle frame as first transmission. – Access the SCISR register and write the data to send in the SCIDR register (this sequence clears the TDRE bit). Repeat this sequence for each data to be transmitted. Clearing the TDRE bit is always performed by the following software sequence: 1. An access to the SCISR register 2. A write to the SCIDR register The TDRE bit is set by hardware and it indicates: – The TDR register is empty. – The data transfer is beginning. – The next data can be written in the SCIDR register without overwriting the previous data. This flag generates an interrupt if the TIE bit is set and the I bit is cleared in the CCR register. When a transmission is taking place, a write instruction to the SCIDR register stores the data in the TDR register and which is copied in the shift register at the end of the current transmission. When no transmission is taking place, a write instruction to the SCIDR register places the data directly in the shift register, the data transmission starts, and the TDRE bit is immediately set. 102/187 When a frame transmission is complete (after the stop bit) the TC bit is set and an interrupt is generated if the TCIE is set and the I bit is cleared in the CCR register. Clearing the TC bit is performed by the following software sequence: 1. An access to the SCISR register 2. A write to the SCIDR register Note: The TDRE and TC bits are cleared by the same software sequence. Break Characters Setting the SBK bit loads the shift register with a break character. The break frame length depends on the M bit (see Figure 2.). As long as the SBK bit is set, the SCI send break frames to the TDO pin. After clearing this bit by software the SCI insert a logic 1 bit at the end of the last break frame to guarantee the recognition of the start bit of the next frame. Idle Characters Setting the TE bit drives the SCI to send an idle frame before the first data frame. Clearing and then setting the TE bit during a transmission sends an idle frame after the current word. Note: Resetting and setting the TE bit causes the data in the TDR register to be lost. Therefore the best time to toggle the TE bit is when the TDRE bit is set, that is, before writing the next byte in the SCIDR. ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) 10.6.4.3 Receiver The SCI can receive data words of either 8 or 9 bits. When the M bit is set, word length is 9 bits and the MSB is stored in the R8 bit in the SCICR1 register. Character reception During a SCI reception, data shifts in least significant bit first through the RDI pin. In this mode, the SCIDR register consists or a buffer (RDR) between the internal bus and the received shift register (see Figure 1.). Procedure – Select the M bit to define the word length. – Select the desired baud rate using the SCIBRR and the SCIERPR registers. – Set the RE bit, this enables the receiver which begins searching for a start bit. When a character is received: – The RDRF bit is set. It indicates that the content of the shift register is transferred to the RDR. – An interrupt is generated if the RIE bit is set and the I bit is cleared in the CCR register. – The error flags can be set if a frame error, noise or an overrun error has been detected during reception. Clearing the RDRF bit is performed by the following software sequence done by: 1. An access to the SCISR register 2. A read to the SCIDR register. The RDRF bit must be cleared before the end of the reception of the next character to avoid an overrun error. Break Character When a break character is received, the SCI handles it as a framing error. Idle Character When a idle frame is detected, there is the same procedure as a data received character plus an interrupt if the ILIE bit is set and the I bit is cleared in the CCR register. Overrun Error An overrun error occurs when a character is received when RDRF has not been reset. Data can not be transferred from the shift register to the RDR register as long as the RDRF bit is not cleared. When an overrun error occurs: – The OR bit is set. – The RDR content is not lost. – The shift register is overwritten. – An interrupt is generated if the RIE bit is set and the I bit is cleared in the CCR register. The OR bit is reset by an access to the SCISR register followed by a SCIDR register read operation. Noise Error Oversampling techniques are used for data recovery by discriminating between valid incoming data and noise. Normal data bits are considered valid if three consecutive samples (8th, 9th, 10th) have the same bit value, otherwise the NF flag is set. In the case of start bit detection, the NF flag is set on the basis of an algorithm combining both valid edge detection and three samples (8th, 9th, 10th). Therefore, to prevent the NF flag getting set during start bit reception, there should be a valid edge detection as well as three valid samples. When noise is detected in a frame: – The NF flag is set at the rising edge of the RDRF bit. – Data is transferred from the Shift register to the SCIDR register. – No interrupt is generated. However this bit rises at the same time as the RDRF bit which itself generates an interrupt. The NF flag is reset by a SCISR register read operation followed by a SCIDR register read operation. During reception, if a false start bit is detected (e.g. 8th, 9th, 10th samples are 011,101,110), the frame is discarded and the receiving sequence is not started for this frame. There is no RDRF bit set for this frame and the NF flag is set internally (not accessible to the user). This NF flag is accessible along with the RDRF bit when a next valid frame is received. Note: If the application Start Bit is not long enough to match the above requirements, then the NF Flag may get set due to the short Start Bit. In this case, the NF flag may be ignored by the application software when the first valid byte is received. See also Section 0.1.4.10 . 103/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) Figure 63. SCI Baud Rate and Extended Prescaler Block Diagram TRANSMITTER CLOCK EXTENDED PRESCALER TRANSMITTER RATE CONTROL SCIETPR EXTENDED TRANSMITTER PRESCALER REGISTER SCIERPR EXTENDED RECEIVER PRESCALER REGISTER RECEIVER CLOCK EXTENDED PRESCALER RECEIVER RATE CONTROL EXTENDED PRESCALER fCPU TRANSMITTER RATE CONTROL /16 /PR SCIBRR SCP1 SCP0 SCT2 SCT1 SCT0 SCR2 SCR1SCR0 RECEIVER RATE CONTROL CONVENTIONAL BAUD RATE GENERATOR 104/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) Framing Error A framing error is detected when: – The stop bit is not recognized on reception at the expected time, following either a de-synchronization or excessive noise. – A break is received. When the framing error is detected: – the FE bit is set by hardware – Data is transferred from the Shift register to the SCIDR register. – No interrupt is generated. However this bit rises at the same time as the RDRF bit which itself generates an interrupt. The FE bit is reset by a SCISR register read operation followed by a SCIDR register read operation. 10.6.4.4 Conventional Baud Rate Generation The baud rate for the receiver and transmitter (Rx and Tx) are set independently and calculated as follows: Tx = fCPU (16*PR)*TR Rx = fCPU (16*PR)*RR with: PR = 1, 3, 4 or 13 (see SCP[1:0] bits) TR = 1, 2, 4, 8, 16, 32, 64,128 (see SCT[2:0] bits) RR = 1, 2, 4, 8, 16, 32, 64,128 (see SCR[2:0] bits) All these bits are in the SCIBRR register. Example: If fCPU is 8 MHz (normal mode) and if PR = 13 and TR = RR = 1, the transmit and receive baud rates are 38400 baud. Note: The baud rate registers MUST NOT be changed while the transmitter or the receiver is enabled. 10.6.4.5 Extended Baud Rate Generation The extended prescaler option gives a very fine tuning on the baud rate, using a 255 value prescaler, whereas the conventional Baud Rate Generator retains industry standard software compatibility. The extended baud rate generator block diagram is described in the Figure 3. The output clock rate sent to the transmitter or to the receiver is the output from the 16 divider divided by a factor ranging from 1 to 255 set in the SCIERPR or the SCIETPR register. Note: the extended prescaler is activated by setting the SCIETPR or SCIERPR register to a value other than zero. The baud rates are calculated as follows: fCPU fCPU Rx = Tx = 16*ERPR*(PR*RR) 16*ETPR*(PR*TR) with: ETPR = 1,..,255 (see SCIETPR register) ERPR = 1,.. 255 (see SCIERPR register) 10.6.4.6 Receiver Muting and Wake-up Feature In multiprocessor configurations it is often desirable that only the intended message recipient should actively receive the full message contents, thus reducing redundant SCI service overhead for all non addressed receivers. The non addressed devices may be placed in sleep mode by means of the muting function. Setting the RWU bit by software puts the SCI in sleep mode: All the reception status bits can not be set. All the receive interrupts are inhibited. A muted receiver may be awakened by one of the following two ways: – by Idle Line detection if the WAKE bit is reset, – by Address Mark detection if the WAKE bit is set. Receiver wakes-up by Idle Line detection when the Receive line has recognized an Idle Frame. Then the RWU bit is reset by hardware but the IDLE bit is not set. Receiver wakes-up by Address Mark detection when it received a “1” as the most significant bit of a word, thus indicating that the message is an address. The reception of this particular word wakes up the receiver, resets the RWU bit and sets the RDRF bit, which allows the receiver to receive this word normally and to use it as an address word. CAUTION: In Mute mode, do not write to the SCICR2 register. If the SCI is in Mute mode during the read operation (RWU = 1) and a address mark wake up event occurs (RWU is reset) before the write operation, the RWU bit is set again by this write operation. Consequently the address byte is lost and the SCI is not woken up from Mute mode. 105/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) 10.6.4.7 Parity Control Parity control (generation of parity bit in transmission and parity checking in reception) can be enabled by setting the PCE bit in the SCICR1 register. Depending on the frame length defined by the M bit, the possible SCI frame formats are as listed in Table 1. Table 21. Frame Formats M bit 0 0 1 1 PCE bit 0 1 0 1 SCI frame | SB | 8 bit data | STB | | SB | 7-bit data | PB | STB | | SB | 9-bit data | STB | | SB | 8-bit data PB | STB | Legend: SB = Start Bit, STB = Stop Bit, PB = Parity Bit Note: In case of wake up by an address mark, the MSB bit of the data is taken into account and not the parity bit Even parity: the parity bit is calculated to obtain an even number of “1s” inside the frame made of the 7 or 8 LSB bits (depending on whether M is equal to 0 or 1) and the parity bit. Example: data = 00110101; 4 bits set => parity bit is 0 if even parity is selected (PS bit = 0). Odd parity: the parity bit is calculated to obtain an odd number of “1s” inside the frame made of the 7 or 8 LSB bits (depending on whether M is equal to 0 or 1) and the parity bit. Example: data = 00110101; 4 bits set => parity bit is 1 if odd parity is selected (PS bit = 1). Transmission mode: If the PCE bit is set then the MSB bit of the data written in the data register is not transmitted but is changed by the parity bit. Reception mode: If the PCE bit is set then the interface checks if the received data byte has an 106/187 even number of “1s” if even parity is selected (PS = 0) or an odd number of “1s” if odd parity is selected (PS = 1). If the parity check fails, the PE flag is set in the SCISR register and an interrupt is generated if PIE is set in the SCICR1 register. 10.6.4.8 SCI Clock Tolerance During reception, each bit is sampled 16 times. The majority of the 8th, 9th and 10th samples is considered as the bit value. For a valid bit detection, all the three samples should have the same value otherwise the noise flag (NF) is set. For example: If the 8th, 9th and 10th samples are 0, 1 and 1 respectively, then the bit value is “1”, but the Noise Flag bit is set because the three samples values are not the same. Consequently, the bit length must be long enough so that the 8th, 9th and 10th samples have the desired bit value. This means the clock frequency should not vary more than 6/16 (37.5%) within one bit. The sampling clock is resynchronized at each start bit, so that when receiving 10 bits (one start bit, 1 data byte, 1 stop bit), the clock deviation must not exceed 3.75%. Note: The internal sampling clock of the microcontroller samples the pin value on every falling edge. Therefore, the internal sampling clock and the time the application expects the sampling to take place may be out of sync. For example: If the baud rate is 15.625 Kbaud (bit length is 64µs), then the 8th, 9th and 10th samples are at 28µs, 32µs and 36µs respectively (the first sample starting ideally at 0µs). But if the falling edge of the internal clock occurs just before the pin value changes, the samples would then be out of sync by ~4us. This means the entire bit length must be at least 40µs (36µs for the 10th sample + 4µs for synchronization with the internal sampling clock). ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) 10.6.4.9 Clock Deviation Causes The causes which contribute to the total deviation are: – DTRA: Deviation due to transmitter error (Local oscillator error of the transmitter or the transmitter is transmitting at a different baud rate). – DQUANT: Error due to the baud rate quantization of the receiver. – DREC: Deviation of the local oscillator of the receiver: This deviation can occur during the reception of one complete SCI message assuming that the deviation has been compensated at the beginning of the message. – DTCL: Deviation due to the transmission line (generally due to the transceivers) All the deviations of the system should be added and compared to the SCI clock tolerance: DTRA + DQUANT + DREC + DTCL < 3.75% 10.6.4.10 Noise Error Causes See also description of Noise error in Section 0.1.4.3 . Start bit The noise flag (NF) is set during start bit reception if one of the following conditions occurs: 1. A valid falling edge is not detected. A falling edge is considered to be valid if the 3 consecutive samples before the falling edge occurs are detected as '1' and, after the falling edge occurs, during the sampling of the 16 samples, if one of the samples numbered 3, 5 or 7 is detected as a “1”. 2. During sampling of the 16 samples, if one of the samples numbered 8, 9 or 10 is detected as a “1”. Therefore, a valid Start Bit must satisfy both the above conditions to prevent the Noise Flag getting set. Data Bits The noise flag (NF) is set during normal data bit reception if the following condition occurs: – During the sampling of 16 samples, if all three samples numbered 8, 9 and10 are not the same. The majority of the 8th, 9th and 10th samples is considered as the bit value. Therefore, a valid Data Bit must have samples 8, 9 and 10 at the same value to prevent the Noise Flag getting set. Figure 64. Bit Sampling in Reception Mode RDI LINE sampled values Sample clock 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 6/16 7/16 7/16 One bit time 107/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) 10.6.5 Low Power Modes 10.6.6 Interrupts The SCI interrupt events are connected to the Mode Description same interrupt vector. No effect on SCI. These events generate an interrupt if the correWAIT SCI interrupts cause the device to exit from sponding Enable Control Bit is set and the interWait mode. rupt mask in the CC register is reset (RIM instrucSCI registers are frozen. tion). HALT In Halt mode, the SCI stops transmitting/receiving until Halt mode is exited. Interrupt Event Enable Exit Event Control from Flag Bit Wait Transmit Data Register TDRE Empty Transmission ComTC plete Received Data Ready RDRF to be Read Overrun Error DetectOR ed Idle Line Detected IDLE Parity Error PE 108/187 Exit from Halt TIE Yes No TCIE Yes No Yes No Yes No Yes Yes No No RIE ILIE PIE ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) 10.6.7 Register Description Note: The IDLE bit is not set again until the RDRF bit has been set itself (that is, a new idle line ocSTATUS REGISTER (SCISR) curs). Read Only Reset Value: 1100 0000 (C0h) Bit 3 = OR Overrun error. 7 0 This bit is set by hardware when the word currently being received in the shift register is ready to be TDRE TC RDRF IDLE OR NF FE PE transferred into the RDR register while RDRF = 1. An interrupt is generated if RIE = 1 in the SCICR2 register. It is cleared by a software sequence (an Bit 7 = TDRE Transmit data register empty. access to the SCISR register followed by a read to This bit is set by hardware when the content of the the SCIDR register). TDR register has been transferred into the shift 0: No Overrun error register. An interrupt is generated if the TIE bit = 1 1: Overrun error is detected in the SCICR2 register. It is cleared by a software sequence (an access to the SCISR register folNote: When this bit is set RDR register content is lowed by a write to the SCIDR register). not lost but the shift register is overwritten. 0: Data is not transferred to the shift register 1: Data is transferred to the shift register Bit 2 = NF Noise flag. Note: Data is not transferred to the shift register This bit is set by hardware when noise is detected unless the TDRE bit is cleared. on a received frame. It is cleared by a software sequence (an access to the SCISR register followed by a read to the SCIDR register). Bit 6 = TC Transmission complete. 0: No noise is detected This bit is set by hardware when transmission of a 1: Noise is detected frame containing Data is complete. An interrupt is generated if TCIE = 1 in the SCICR2 register. It is Note: This bit does not generate interrupt as it apcleared by a software sequence (an access to the pears at the same time as the RDRF bit which itSCISR register followed by a write to the SCIDR self generates an interrupt. register). 0: Transmission is not complete 1: Transmission is complete Bit 1 = FE Framing error. This bit is set by hardware when a de-synchronizaNote: TC is not set after the transmission of a Pretion, excessive noise or a break character is deamble or a Break. tected. It is cleared by a software sequence (an access to the SCISR register followed by a read to Bit 5 = RDRF Received data ready flag. the SCIDR register). This bit is set by hardware when the content of the 0: No Framing error is detected RDR register has been transferred to the SCIDR 1: Framing error or break character is detected register. An interrupt is generated if RIE = 1 in the Note: This bit does not generate interrupt as it apSCICR2 register. It is cleared by a software sepears at the same time as the RDRF bit which itquence (an access to the SCISR register followed self generates an interrupt. If the word currently by a read to the SCIDR register). being transferred causes both frame error and 0: Data is not received overrun error, it will be transferred and only the OR 1: Received data is ready to be read bit will be set. Bit 4 = IDLE Idle line detect. This bit is set by hardware when a Idle Line is detected. An interrupt is generated if the ILIE = 1 in the SCICR2 register. It is cleared by a software sequence (an access to the SCISR register followed by a read to the SCIDR register). 0: No Idle Line is detected 1: Idle Line is detected Bit 0 = PE Parity error. This bit is set by hardware when a parity error occurs in receiver mode. It is cleared by a software sequence (a read to the status register followed by an access to the SCIDR data register). An interrupt is generated if PIE = 1 in the SCICR1 register. 0: No parity error 1: Parity error 109/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) CONTROL REGISTER 1 (SCICR1) Read/Write Bit 3 = WAKE Wake-Up method. This bit determines the SCI Wake-Up method, it is Reset Value: x000 0000 (x0h) set or cleared by software. 0: Idle Line 7 0 1: Address Mark R8 T8 SCID M WAKE PCE PS PIE Bit 7 = R8 Receive data bit 8. This bit is used to store the 9th bit of the received word when M = 1. Bit 6 = T8 Transmit data bit 8. This bit is used to store the 9th bit of the transmitted word when M = 1. Bit 5 = SCID Disabled for low power consumption When this bit is set the SCI prescalers and outputs are stopped and the end of the current byte transfer in order to reduce power consumption.This bit is set and cleared by software. 0: SCI enabled 1: SCI prescaler and outputs disabled Bit 4 = M Word length. This bit determines the word length. It is set or cleared by software. 0: 1 Start bit, 8 Data bits, 1 Stop bit 1: 1 Start bit, 9 Data bits, 1 Stop bit Note: The M bit must not be modified during a data transfer (both transmission and reception). 110/187 Bit 2 = PCE Parity control enable. This bit selects the hardware parity control (generation and detection). When the parity control is enabled, the computed parity is inserted at the MSB position (9th bit if M = 1; 8th bit if M = 0) and parity is checked on the received data. This bit is set and cleared by software. Once it is set, PCE is active after the current byte (in reception and in transmission). 0: Parity control disabled 1: Parity control enabled Bit 1 = PS Parity selection. This bit selects the odd or even parity when the parity generation/detection is enabled (PCE bit set). It is set and cleared by software. The parity is selected after the current byte. 0: Even parity 1: Odd parity Bit 0 = PIE Parity interrupt enable. This bit enables the interrupt capability of the hardware parity control when a parity error is detected (PE bit set). It is set and cleared by software. 0: Parity error interrupt disabled 1: Parity error interrupt enabled. ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) CONTROL REGISTER 2 (SCICR2) Notes: Read/Write – During transmission, a “0” pulse on the TE bit (“0” followed by “1”) sends a preamble (idle line) Reset Value: 0000 0000 (00h) after the current word. 7 0 – When TE is set there is a 1 bit-time delay before the transmission starts. TIE TCIE RIE ILIE TE RE RWU SBK CAUTION: The TDO pin is free for general purpose I/O only when the TE and RE bits are both cleared (or if TE is never set). Bit 7 = TIE Transmitter interrupt enable. This bit is set and cleared by software. 0: Interrupt is inhibited Bit 2 = RE Receiver enable. 1: An SCI interrupt is generated whenever This bit enables the receiver. It is set and cleared TDRE=1 in the SCISR register by software. 0: Receiver is disabled Bit 6 = TCIE Transmission complete interrupt ena1: Receiver is enabled and begins searching for a ble start bit This bit is set and cleared by software. 0: Interrupt is inhibited Bit 1 = RWU Receiver wake-up. 1: An SCI interrupt is generated whenever TC=1 in This bit determines if the SCI is in mute mode or the SCISR register not. It is set and cleared by software and can be cleared by hardware when a wake-up sequence is Bit 5 = RIE Receiver interrupt enable. recognized. This bit is set and cleared by software. 0: Receiver in Active mode 0: Interrupt is inhibited 1: Receiver in Mute mode 1: An SCI interrupt is generated whenever OR=1 Note: Before selecting Mute mode (setting the or RDRF=1 in the SCISR register RWU bit), the SCI must receive some data first, otherwise it cannot function in Mute mode with Bit 4 = ILIE Idle line interrupt enable. wake-up by idle line detection. This bit is set and cleared by software. 0: Interrupt is inhibited Bit 0 = SBK Send break. 1: An SCI interrupt is generated whenever IDLE=1 This bit set is used to send break characters. It is in the SCISR register. set and cleared by software. Bit 3 = TE Transmitter enable. This bit enables the transmitter. It is set and cleared by software. 0: Transmitter is disabled 1: Transmitter is enabled 0: No break character is transmitted 1: Break characters are transmitted Note: If the SBK bit is set to “1” and then to “0”, the transmitter sends a BREAK word at the end of the current word. 111/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) DATA REGISTER (SCIDR) Read/Write Reset Value: Undefined Contains the Received or Transmitted data character, depending on whether it is read from or written to. 7 0 DR7 DR6 DR5 DR4 DR3 DR2 DR1 DR0 The Data register performs a double function (read and write) since it is composed of two registers, one for transmission (TDR) and one for reception (RDR). The TDR register provides the parallel interface between the internal bus and the output shift register (see Figure 1.). The RDR register provides the parallel interface between the input shift register and the internal bus (see Figure 1.). BAUD RATE REGISTER (SCIBRR) Read/Write Reset Value: 0000 0000 (00h) 7 0 SCP1 SCP0 SCT2 SCT1 SCT0 SCR2 SCR1 SCR0 Bits 7:6 = SCP[1:0] First SCI Prescaler These 2 prescaling bits allow several standard clock division ranges: PR Prescaling factor SCP1 SCP0 1 0 0 3 0 1 4 1 0 13 1 1 112/187 Bits 5:3 = SCT[2:0] SCI Transmitter rate divisor These 3 bits, in conjunction with the SCP1 & SCP0 bits define the total division applied to the bus clock to yield the transmit rate clock in conventional Baud Rate Generator mode. TR dividing factor SCT2 SCT1 SCT0 1 0 0 0 2 0 0 1 4 0 1 0 8 0 1 1 16 1 0 0 32 1 0 1 64 1 1 0 128 1 1 1 Bits 2:0 = SCR[2:0] SCI Receiver rate divisor. These 3 bits, in conjunction with the SCP[1:0] bits define the total division applied to the bus clock to yield the receive rate clock in conventional Baud Rate Generator mode. RR Dividing factor SCR2 SCR1 SCR0 1 0 0 0 2 0 0 1 4 0 1 0 8 0 1 1 16 1 0 0 32 1 0 1 64 1 1 0 128 1 1 1 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATIONS INTERFACE (Cont’d) EXTENDED RECEIVE PRESCALER DIVISION REGISTER (SCIERPR) Read/Write Reset Value: 0000 0000 (00h) Allows setting of the Extended Prescaler rate division factor for the receive circuit. 7 0 EXTENDED TRANSMIT PRESCALER DIVISION REGISTER (SCIETPR) Read/Write Reset Value:0000 0000 (00h) Allows setting of the External Prescaler rate division factor for the transmit circuit. 7 ERPR ERPR ERPR ERPR ERPR ERPR ERPR ERPR 7 6 5 4 3 2 1 0 ETPR 7 Bits 7:0 = ERPR[7:0] 8-bit Extended Receive Prescaler Register. The extended Baud Rate Generator is activated when a value different from 00h is stored in this register. Therefore the clock frequency issued from the 16 divider (see Figure 3.) is divided by the binary factor set in the SCIERPR register (in the range 1 to 255). The extended baud rate generator is not used after a reset. 0 ETPR 6 ETPR 5 ETPR 4 ETPR 3 ETPR 2 ETPR ETPR 1 0 Bits 7:0 = ETPR[7:0] 8-bit Extended Transmit Prescaler Register. The extended Baud Rate Generator is activated when a value different from 00h is stored in this register. Therefore the clock frequency issued from the 16 divider (see Figure 3.) is divided by the binary factor set in the SCIETPR register (in the range 1 to 255). The extended baud rate generator is not used after a reset. Table 22. Baudrate Selection Conditions Symbol fTx fRx Parameter fCPU Accuracy vs Standard Prescaler ~0.16% Conventional Mode TR (or RR)=128, PR=13 TR (or RR)= 32, PR=13 TR (or RR)= 16, PR=13 TR (or RR)= 8, PR=13 TR (or RR)= 4, PR=13 TR (or RR)= 16, PR= 3 TR (or RR)= 2, PR=13 TR (or RR)= 1, PR=13 Communication frequency 8 MHz ~0.79% Extended Mode ETPR (or ERPR) = 35, TR (or RR)= 1, PR=1 Standard 300 1200 2400 4800 9600 10400 19200 38400 Baud Rate Unit ~300.48 ~1201.92 ~2403.84 ~4807.69 ~9615.38 ~10416.67 ~19230.77 ~38461.54 Hz 14400 ~14285.71 113/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx SERIAL COMMUNICATION INTERFACE (Cont’d) Table 23. SCI Register Map and Reset Values Address (Hex.) 0050h 0051h 0052h 0053h 0054h 0055h 0057h 114/187 Register Label 7 6 5 4 3 2 1 0 SCISR Reset Value SCIDR Reset Value SCIBRR Reset Value SCICR1 Reset Value SCICR2 Reset Value SCIERPR Reset Value SCIPETPR Reset Value TDRE 1 MSB x SCP1 0 R8 x TIE 0 MSB 0 MSB 0 TC 1 RDRF 0 IDLE 0 OVR 0 NF 0 FE 0 x SCP0 0 T8 0 TCIE 0 x SCT2 0 SCID 0 RIE 0 x SCT1 0 M 0 ILIE 0 x SCT0 0 WAKE 0 TE 0 x SCR2 0 PCE 0 RE 0 x SCR1 0 PS 0 RWU 0 0 0 0 0 0 0 0 0 0 0 0 0 PE 0 LSB x SCR0 0 PIE 0 SBK 0 LSB 0 LSB 0 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 10.7 I2C BUS INTERFACE (I2C) 10.7.1 Introduction The I2C Bus Interface serves as an interface between the microcontroller and the serial I2C bus. It provides both multimaster and slave functions, and controls all I2C bus-specific sequencing, protocol, arbitration and timing. It supports fast I2C mode (400kHz). 10.7.2 Main Features 2 ■ Parallel-bus/I C protocol converter ■ Multi-master capability ■ 7-bit/10-bit Addressing ■ SMBus V1.1 Compliant ■ Transmitter/Receiver flag ■ End-of-byte transmission flag ■ Transfer problem detection I2C Master Features: ■ Clock generation 2 ■ I C bus busy flag ■ Arbitration Lost Flag ■ End of byte transmission flag ■ Transmitter/Receiver Flag ■ Start bit detection flag ■ Start and Stop generation I2C Slave Features: ■ Stop bit detection 2 ■ I C bus busy flag ■ Detection of misplaced start or stop condition 2 ■ Programmable I C Address detection ■ Transfer problem detection ■ End-of-byte transmission flag ■ Transmitter/Receiver flag 10.7.3 General Description In addition to receiving and transmitting data, this interface converts it from serial to parallel format and vice versa, using either an interrupt or polled handshake. The interrupts are enabled or disabled by software. The interface is connected to the I2C bus by a data pin (SDAI) and by a clock pin (SCLI). It can be connected both with a standard I2C bus and a Fast I2C bus. This selection is made by software. Mode Selection The interface can operate in the four following modes: – Slave transmitter/receiver – Master transmitter/receiver By default, it operates in slave mode. The interface automatically switches from slave to master after it generates a START condition and from master to slave in case of arbitration loss or a STOP generation, allowing then Multi-Master capability. Communication Flow In Master mode, it initiates a data transfer and generates the clock signal. A serial data transfer always begins with a start condition and ends with a stop condition. Both start and stop conditions are generated in master mode by software. In Slave mode, the interface is capable of recognising its own address (7 or 10-bit), and the General Call address. The General Call address detection may be enabled or disabled by software. Data and addresses are transferred as 8-bit bytes, MSB first. The first byte(s) following the start condition contain the address (one in 7-bit mode, two in 10-bit mode). The address is always transmitted in Master mode. A 9th clock pulse follows the 8 clock cycles of a byte transfer, during which the receiver must send an acknowledge bit to the transmitter. Refer to Figure 65. Figure 65. I2C BUS Protocol SDA ACK MSB SCL 1 START CONDITION 2 8 9 STOP CONDITION VR02119B 115/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I2C BUS INTERFACE (Cont’d) Acknowledge may be enabled and disabled by software. The I2C interface address and/or general call address can be selected by software. The speed of the I2C interface may be selected between Standard (up to 100KHz) and Fast I2C (up to 400KHz). SDA/SCL Line Control Transmitter mode: the interface holds the clock line low before transmission to wait for the microcontroller to write the byte in the Data Register. Receiver mode: the interface holds the clock line low after reception to wait for the microcontroller to read the byte in the Data Register. The SCL frequency (Fscl) is controlled by a programmable clock divider which depends on the I2C bus mode. When the I2C cell is enabled, the SDA and SCL ports must be configured as floating inputs. In this case, the value of the external pull-up resistor used depends on the application. When the I2C cell is disabled, the SDA and SCL ports revert to being standard I/O port pins. Figure 66. I2C Interface Block Diagram DATA REGISTER (DR) SDA or SDAI DATA CONTROL DATA SHIFT REGISTER COMPARATOR OWN ADDRESS REGISTER 1 (OAR1) OWN ADDRESS REGISTER 2 (OAR2) SCL or SCLI CLOCK CONTROL CLOCK CONTROL REGISTER (CCR) CONTROL REGISTER (CR) STATUS REGISTER 1 (SR1) CONTROL LOGIC STATUS REGISTER 2 (SR2) INTERRUPT 116/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I2C BUS INTERFACE (Cont’d) 10.7.4 Functional Description Refer to the CR, SR1 and SR2 registers in Section 10.7.7. for the bit definitions. By default the I2C interface operates in Slave mode (M/SL bit is cleared) except when it initiates a transmit or receive sequence. First the interface frequency must be configured using the FRi bits in the OAR2 register. 10.7.4.1 Slave Mode As soon as a start condition is detected, the address is received from the SDA line and sent to the shift register; then it is compared with the address of the interface or the General Call address (if selected by software). Note: In 10-bit addressing mode, the comparison includes the header sequence (11110xx0) and the two most significant bits of the address. Header matched (10-bit mode only): the interface generates an acknowledge pulse if the ACK bit is set. Address not matched: the interface ignores it and waits for another Start condition. Address matched: the interface generates in sequence: – Acknowledge pulse if the ACK bit is set. – EVF and ADSL bits are set with an interrupt if the ITE bit is set. Then the interface waits for a read of the SR1 register, holding the SCL line low (see Figure 67 Transfer sequencing EV1). Next, in 7-bit mode read the DR register to determine from the least significant bit (Data Direction Bit) if the slave must enter Receiver or Transmitter mode. In 10-bit mode, after receiving the address sequence the slave is always in receive mode. It will enter transmit mode on receiving a repeated Start condition followed by the header sequence with matching address bits and the least significant bit set (11110xx1). Slave Receiver Following the address reception and after SR1 register has been read, the slave receives bytes from the SDA line into the DR register via the internal shift register. After each byte the interface generates in sequence: – Acknowledge pulse if the ACK bit is set – EVF and BTF bits are set with an interrupt if the ITE bit is set. Then the interface waits for a read of the SR1 register followed by a read of the DR register, holding the SCL line low (see Figure 67 Transfer sequencing EV2). Slave Transmitter Following the address reception and after SR1 register has been read, the slave sends bytes from the DR register to the SDA line via the internal shift register. The slave waits for a read of the SR1 register followed by a write in the DR register, holding the SCL line low (see Figure 67 Transfer sequencing EV3). When the acknowledge pulse is received: – The EVF and BTF bits are set by hardware with an interrupt if the ITE bit is set. Closing slave communication After the last data byte is transferred a Stop Condition is generated by the master. The interface detects this condition and sets: – EVF and STOPF bits with an interrupt if the ITE bit is set. Then the interface waits for a read of the SR2 register (see Figure 67 Transfer sequencing EV4). Error Cases – BERR: Detection of a Stop or a Start condition during a byte transfer. In this case, the EVF and the BERR bits are set with an interrupt if the ITE bit is set. If it is a Stop then the interface discards the data, released the lines and waits for another Start condition. If it is a Start then the interface discards the data and waits for the next slave address on the bus. – AF: Detection of a non-acknowledge bit. In this case, the EVF and AF bits are set with an interrupt if the ITE bit is set. The AF bit is cleared by reading the I2CSR2 register. However, if read before the completion of the transmission, the AF flag will be set again, thus possibly generating a new interrupt. Software must ensure either that the SCL line is back at 0 before reading the SR2 register, or be able to correctly handle a second interrupt during the 9th pulse of a transmitted byte. Note: In case of errors, SCL line is not held low; however, the SDA line can remain low if the last bits transmitted are all 0. While AF=1, the SCL line may be held low due to SB or BTF flags that are set at the same time. It is then necessary to release both lines by software. 117/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I2C INTERFACE (Cont’d) How to release the SDA / SCL lines Set and subsequently clear the STOP bit while BTF is set. The SDA/SCL lines are released after the transfer of the current byte. SMBus Compatibility ST7 I2C is compatible with SMBus V1.1 protocol. It supports all SMBus adressing modes, SMBus bus protocols and CRC-8 packet error checking. Refer to AN1713: SMBus Slave Driver For ST7 I2C Peripheral. 10.7.4.2 Master Mode To switch from default Slave mode to Master mode a Start condition generation is needed. Start condition Setting the START bit while the BUSY bit is cleared causes the interface to switch to Master mode (M/SL bit set) and generates a Start condition. Once the Start condition is sent: – The EVF and SB bits are set by hardware with an interrupt if the ITE bit is set. Then the master waits for a read of the SR1 register followed by a write in the DR register with the Slave address, holding the SCL line low (see Figure 67 Transfer sequencing EV5). Slave address transmission Then the slave address is sent to the SDA line via the internal shift register. In 7-bit addressing mode, one address byte is sent. In 10-bit addressing mode, sending the first byte including the header sequence causes the following event: – The EVF bit is set by hardware with interrupt generation if the ITE bit is set. Then the master waits for a read of the SR1 register followed by a write in the DR register, holding the SCL line low (see Figure 67 Transfer sequencing EV9). 118/187 Then the second address byte is sent by the interface. After completion of this transfer (and acknowledge from the slave if the ACK bit is set): – The EVF bit is set by hardware with interrupt generation if the ITE bit is set. Then the master waits for a read of the SR1 register followed by a write in the CR register (for example set PE bit), holding the SCL line low (see Figure 67 Transfer sequencing EV6). Next the master must enter Receiver or Transmitter mode. Note: In 10-bit addressing mode, to switch the master to Receiver mode, software must generate a repeated Start condition and resend the header sequence with the least significant bit set (11110xx1). Master Receiver Following the address transmission and after SR1 and CR registers have been accessed, the master receives bytes from the SDA line into the DR register via the internal shift register. After each byte the interface generates in sequence: – Acknowledge pulse if the ACK bit is set – EVF and BTF bits are set by hardware with an interrupt if the ITE bit is set. Then the interface waits for a read of the SR1 register followed by a read of the DR register, holding the SCL line low (see Figure 67 Transfer sequencing EV7). To close the communication: before reading the last byte from the DR register, set the STOP bit to generate the Stop condition. The interface goes automatically back to slave mode (M/SL bit cleared). Note: In order to generate the non-acknowledge pulse after the last received data byte, the ACK bit must be cleared just before reading the second last data byte. ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I2C BUS INTERFACE (Cont’d) Master Transmitter Following the address transmission and after SR1 register has been read, the master sends bytes from the DR register to the SDA line via the internal shift register. The master waits for a read of the SR1 register followed by a write in the DR register, holding the SCL line low (see Figure 67 Transfer sequencing EV8). When the acknowledge bit is received, the interface sets: – EVF and BTF bits with an interrupt if the ITE bit is set. To close the communication: after writing the last byte to the DR register, set the STOP bit to generate the Stop condition. The interface goes automatically back to slave mode (M/SL bit cleared). Error Cases – BERR: Detection of a Stop or a Start condition during a byte transfer. In this case, the EVF and BERR bits are set by hardware with an interrupt if ITE is set. Note that BERR will not be set if an error is detected during the first or second pulse of each 9bit transaction: Single Master Mode If a Start or Stop is issued during the first or second pulse of a 9-bit transaction, the BERR flag will not be set and transfer will continue however the BUSY flag will be reset. To work around this, slave devices should issue a NACK when they receive a misplaced Start or Stop. The reception of a NACK or BUSY by the master in the middle of communication gives the possibility to reinitiate transmission. Multimaster Mode Normally the BERR bit would be set whenever unauthorized transmission takes place while transfer is already in progress. However, an issue will arise if an external master generates an unauthorized Start or Stop while the I2C master is on the first or second pulse of a 9-bit transaction. It is possible to work around this by polling the BUSY bit during I2C master mode transmission. The resetting of the BUSY bit can then be handled in a similar manner as the BERR flag being set. – AF: Detection of a non-acknowledge bit. In this case, the EVF and AF bits are set by hardware with an interrupt if the ITE bit is set. To resume, set the Start or Stop bit. The AF bit is cleared by reading the I2CSR2 register. However, if read before the completion of the transmission, the AF flag will be set again, thus possibly generating a new interrupt. Software must ensure either that the SCL line is back at 0 before reading the SR2 register, or be able to correctly handle a second interrupt during the 9th pulse of a transmitted byte. – ARLO: Detection of an arbitration lost condition. In this case the ARLO bit is set by hardware (with an interrupt if the ITE bit is set and the interface goes automatically back to slave mode (the M/SL bit is cleared). Note: In all these cases, the SCL line is not held low; however, the SDA line can remain low due to possible «0» bits transmitted last. It is then necessary to release both lines by software. 119/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I2C BUS INTERFACE (Cont’d) Figure 67. Transfer Sequencing 7-bit Slave receiver: S Address A Data1 A Data2 EV1 A EV2 EV2 ..... DataN A P EV2 EV4 7-bit Slave transmitter: S Address A Data1 A EV1 EV3 Data2 A EV3 EV3 DataN ..... NA P EV3-1 EV4 7-bit Master receiver: S Address A EV5 Data1 A EV6 Data2 A EV7 EV7 DataN ..... NA P EV7 7-bit Master transmitter: S Address A EV5 Data1 A EV6 EV8 Data2 A EV8 DataN ..... EV8 A P EV8 10-bit Slave receiver: S Header A Address A Data1 A EV1 ..... EV2 DataN A P EV2 EV4 10-bit Slave transmitter: Sr Header A Data1 A EV1 EV3 EV3 .... DataN . A P EV3-1 EV4 10-bit Master transmitter S Header EV5 A Address EV9 A Data1 A EV6 EV8 EV8 DataN ..... A P EV8 10-bit Master receiver: Sr Header EV5 A Data1 EV6 A EV7 ..... DataN Legend: S=Start, Sr = Repeated Start, P=Stop, A=Acknowledge, NA=Non-acknowledge, EVx=Event (with interrupt if ITE=1) EV1: EVF=1, ADSL=1, cleared by reading SR1 register. EV2: EVF=1, BTF=1, cleared by reading SR1 register followed by reading DR register. EV3: EVF=1, BTF=1, cleared by reading SR1 register followed by writing DR register. EV3-1: EVF=1, AF=1, BTF=1; AF is cleared by reading SR1 register. BTF is cleared by releasing the lines (STOP=1, STOP=0) or by writing DR register (DR=FFh). Note: If lines are released by STOP=1, STOP=0, the subsequent EV4 is not seen. EV4: EVF=1, STOPF=1, cleared by reading SR2 register. EV5: EVF=1, SB=1, cleared by reading SR1 register followed by writing DR register. EV6: EVF=1, cleared by reading SR1 register followed by writing CR register (for example PE=1). EV7: EVF=1, BTF=1, cleared by reading SR1 register followed by reading DR register. EV8: EVF=1, BTF=1, cleared by reading SR1 register followed by writing DR register. EV9: EVF=1, ADD10=1, cleared by reading SR1 register followed by writing DR register. 120/187 A P EV7 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I2C BUS INTERFACE (Cont’d) 10.7.5 Low Power Modes Mode WAIT HALT Description No effect on I2C interface. I2C interrupts cause the device to exit from WAIT mode. I2C registers are frozen. In HALT mode, the I2C interface is inactive and does not acknowledge data on the bus. The I2C interface resumes operation when the MCU is woken up by an interrupt with “exit from HALT mode” capability. 10.7.6 Interrupts Figure 68. Event Flags and Interrupt Generation ADD10 BTF ADSL SB AF STOPF ARLO BERR ITE INTERRUPT EVF * * EVF can also be set by EV6 or an error from the SR2 register. Interrupt Event 10-bit Address Sent Event (Master mode) End of Byte Transfer Event Address Matched Event (Slave mode) Start Bit Generation Event (Master mode) Acknowledge Failure Event Stop Detection Event (Slave mode) Arbitration Lost Event (Multimaster configuration) Bus Error Event Event Flag Enable Control Bit ADD10 BTF ADSEL SB AF STOPF ARLO BERR ITE Exit from Wait Yes Yes Yes Yes Yes Yes Yes Yes Exit from Halt No No No No No No No No Note: The I2C 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 I-bit in the CC register is reset (RIM instruction). 121/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I2C BUS INTERFACE (Cont’d) 10.7.7 Register Description I2C CONTROL REGISTER (CR) Read / Write Reset Value: 0000 0000 (00h) – In slave mode: 0: No start generation 1: Start generation when the bus is free 7 0 0 0 PE ENGC START ACK STOP ITE Bit 2 = ACK Acknowledge enable. This bit is set and cleared by software. It is also cleared by hardware when the interface is disabled (PE=0). 0: No acknowledge returned 1: Acknowledge returned after an address byte or a data byte is received Bit 7:6 = Reserved. Forced to 0 by hardware. Bit 5 = PE Peripheral enable. This bit is set and cleared by software. 0: Peripheral disabled 1: Master/Slave capability Notes: – When PE=0, all the bits of the CR register and the SR register except the Stop bit are reset. All outputs are released while PE=0 – When PE=1, the corresponding I/O pins are selected by hardware as alternate functions. – To enable the I2C interface, write the CR register TWICE with PE=1 as the first write only activates the interface (only PE is set). Bit 4 = ENGC Enable General Call. This bit is set and cleared by software. It is also cleared by hardware when the interface is disabled (PE=0). The 00h General Call address is acknowledged (01h ignored). 0: General Call disabled 1: General Call enabled Note: In accordance with the I2C standard, when GCAL addressing is enabled, an I2C slave can only receive data. It will not transmit data to the master. Bit 3 = START Generation of a Start condition. This bit is set and cleared by software. It is also cleared by hardware when the interface is disabled (PE=0) or when the Start condition is sent (with interrupt generation if ITE=1). – In master mode: 0: No start generation 1: Repeated start generation 122/187 Bit 1 = STOP Generation of a Stop condition. This bit is set and cleared by software. It is also cleared by hardware in master mode. Note: This bit is not cleared when the interface is disabled (PE=0). – In master mode: 0: No stop generation 1: Stop generation after the current byte transfer or after the current Start condition is sent. The STOP bit is cleared by hardware when the Stop condition is sent. – In slave mode: 0: No stop generation 1: Release the SCL and SDA lines after the current byte transfer (BTF=1). In this mode the STOP bit has to be cleared by software. Bit 0 = ITE Interrupt enable. This bit is set and cleared by software and cleared by hardware when the interface is disabled (PE=0). 0: Interrupts disabled 1: Interrupts enabled Refer to Figure 68 for the relationship between the events and the interrupt. SCL is held low when the ADD10, SB, BTF or ADSL flags or an EV6 event (See Figure 67) is detected. ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I2C BUS INTERFACE (Cont’d) I2C STATUS REGISTER 1 (SR1) Read Only Reset Value: 0000 0000 (00h) 1: Data byte transmitted 7 EVF 0 ADD10 TRA BUSY BTF ADSL M/SL SB Bit 7 = EVF Event flag. This bit is set by hardware as soon as an event occurs. It is cleared by software reading SR2 register in case of error event or as described in Figure 67. It is also cleared by hardware when the interface is disabled (PE=0). 0: No event 1: One of the following events has occurred: – BTF=1 (Byte received or transmitted) – ADSL=1 (Address matched in Slave mode while ACK=1) – SB=1 (Start condition generated in Master mode) – AF=1 (No acknowledge received after byte transmission) – STOPF=1 (Stop condition detected in Slave mode) – ARLO=1 (Arbitration lost in Master mode) – BERR=1 (Bus error, misplaced Start or Stop condition detected) – ADD10=1 (Master has sent header byte) – Address byte successfully transmitted in Master mode. Bit 6 = ADD10 10-bit addressing in Master mode. This bit is set by hardware when the master has sent the first byte in 10-bit address mode. It is cleared by software reading SR2 register followed by a write in the DR register of the second address byte. It is also cleared by hardware when the peripheral is disabled (PE=0). 0: No ADD10 event occurred. 1: Master has sent first address byte (header) Bit 5 = TRA Transmitter/Receiver. When BTF is set, TRA=1 if a data byte has been transmitted. It is cleared automatically when BTF is cleared. It is also cleared by hardware after detection of Stop condition (STOPF=1), loss of bus arbitration (ARLO=1) or when the interface is disabled (PE=0). 0: Data byte received (if BTF=1) Bit 4 = BUSY Bus busy. This bit is set by hardware on detection of a Start condition and cleared by hardware on detection of a Stop condition. It indicates a communication in progress on the bus. The BUSY flag of the I2CSR1 register is cleared if a Bus Error occurs. 0: No communication on the bus 1: Communication ongoing on the bus Note: – The BUSY flag is NOT updated when the interface is disabled (PE=0). This can have consequences when operating in Multimaster mode; i.e. a second active I2C master commencing a transfer with an unset BUSY bit can cause a conflict resulting in lost data. A software workaround consists of checking that the I2C is not busy before enabling the I2C Multimaster cell. Bit 3 = BTF Byte transfer finished. This bit is set by hardware as soon as a byte is correctly received or transmitted with interrupt generation if ITE=1. It is cleared by software reading SR1 register followed by a read or write of DR register. It is also cleared by hardware when the interface is disabled (PE=0). – Following a byte transmission, this bit is set after reception of the acknowledge clock pulse. In case an address byte is sent, this bit is set only after the EV6 event (See Figure 67). BTF is cleared by reading SR1 register followed by writing the next byte in DR register. – Following a byte reception, this bit is set after transmission of the acknowledge clock pulse if ACK=1. BTF is cleared by reading SR1 register followed by reading the byte from DR register. The SCL line is held low while BTF=1. 0: Byte transfer not done 1: Byte transfer succeeded Bit 2 = ADSL Address matched (Slave mode). This bit is set by hardware as soon as the received slave address matched with the OAR register content or a general call is recognized. An interrupt is generated if ITE=1. It is cleared by software reading SR1 register or by hardware when the interface is disabled (PE=0). The SCL line is held low while ADSL=1. 0: Address mismatched or not received 1: Received address matched 123/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I2C BUS INTERFACE (Cont’d) Bit 1 = M/SL Master/Slave. This bit is set by hardware as soon as the interface is in Master mode (writing START=1). It is cleared by hardware after detecting a Stop condition on the bus or a loss of arbitration (ARLO=1). It is also cleared when the interface is disabled (PE=0). 0: Slave mode 1: Master mode Bit 0 = SB Start bit (Master mode). This bit is set by hardware as soon as the Start condition is generated (following a write START=1). An interrupt is generated if ITE=1. It is cleared by software reading SR1 register followed by writing the address byte in DR register. It is also cleared by hardware when the interface is disabled (PE=0). 0: No Start condition 1: Start condition generated I2C STATUS REGISTER 2 (SR2) Read Only Reset Value: 0000 0000 (00h) 7 0 0 0 0 AF STOPF ARLO BERR GCAL Bit 7:5 = Reserved. Forced to 0 by hardware. Bit 4 = AF Acknowledge failure. This bit is set by hardware when no acknowledge is returned. An interrupt is generated if ITE=1. It is cleared by software reading SR2 register or by hardware when the interface is disabled (PE=0). The SCL line is not held low while AF=1 but by other flags (SB or BTF) that are set at the same time. 0: No acknowledge failure 1: Acknowledge failure Note: – When an AF event occurs, the SCL line is not held low; however, the SDA line can remain low if the last bits transmitted are all 0. It is then necessary to release both lines by software. Bit 3 = STOPF Stop detection (Slave mode). This bit is set by hardware when a Stop condition is detected on the bus after an acknowledge (if ACK=1). An interrupt is generated if ITE=1. It is cleared by software reading SR2 register or by hardware when the interface is disabled (PE=0). 124/187 The SCL line is not held low while STOPF=1. 0: No Stop condition detected 1: Stop condition detected Bit 2 = ARLO Arbitration lost. This bit is set by hardware when the interface loses the arbitration of the bus to another master. An interrupt is generated if ITE=1. It is cleared by software reading SR2 register or by hardware when the interface is disabled (PE=0). After an ARLO event the interface switches back automatically to Slave mode (M/SL=0). The SCL line is not held low while ARLO=1. 0: No arbitration lost detected 1: Arbitration lost detected Note: – In a Multimaster environment, when the interface is configured in Master Receive mode it does not perform arbitration during the reception of the Acknowledge Bit. Mishandling of the ARLO bit from the I2CSR2 register may occur when a second master simultaneously requests the same data from the same slave and the I2C master does not acknowledge the data. The ARLO bit is then left at 0 instead of being set. Bit 1 = BERR Bus error. This bit is set by hardware when the interface detects a misplaced Start or Stop condition. An interrupt is generated if ITE=1. It is cleared by software reading SR2 register or by hardware when the interface is disabled (PE=0). The SCL line is not held low while BERR=1. 0: No misplaced Start or Stop condition 1: Misplaced Start or Stop condition Note: – If a Bus Error occurs, a Stop or a repeated Start condition should be generated by the Master to re-synchronize communication, get the transmission acknowledged and the bus released for further communication Bit 0 = GCAL General Call (Slave mode). This bit is set by hardware when a general call address is detected on the bus while ENGC=1. It is cleared by hardware detecting a Stop condition (STOPF=1) or when the interface is disabled (PE=0). 0: No general call address detected on bus 1: general call address detected on bus ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I2C BUS INTERFACE (Cont’d) I2C CLOCK CONTROL REGISTER (CCR) Read / Write Reset Value: 0000 0000 (00h) 7 FM/SM CC6 CC5 CC4 CC3 CC2 CC1 I2C DATA REGISTER (DR) Read / Write Reset Value: 0000 0000 (00h) 0 7 CC0 D7 Bit 7 = FM/SM Fast/Standard I2C mode. This bit is set and cleared by software. It is not cleared when the interface is disabled (PE=0). 0: Standard I2C mode 1: Fast I2C mode Bit 6:0 = CC[6:0] 7-bit clock divider. These bits select the speed of the bus (FSCL) depending on the I2C mode. They are not cleared when the interface is disabled (PE=0). Refer to the Electrical Characteristics section for the table of values. Note: The programmed FSCL assumes no load on SCL and SDA lines. 0 D6 D5 D4 D3 D2 D1 D0 Bit 7:0 = D[7:0] 8-bit Data Register. These bits contain the byte to be received or transmitted on the bus. – Transmitter mode: Byte transmission start automatically when the software writes in the DR register. – Receiver mode: the first data byte is received automatically in the DR register using the least significant bit of the address. Then, the following data bytes are received one by one after reading the DR register. 125/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I2C BUS INTERFACE (Cont’d) I2C OWN ADDRESS REGISTER (OAR1) Read / Write Reset Value: 0000 0000 (00h) 7 ADD7 ADD6 ADD5 ADD4 ADD3 ADD2 ADD1 I2C OWN ADDRESS REGISTER (OAR2) Read / Write Reset Value: 0100 0000 (40h) 0 7 ADD0 FR1 7-bit Addressing Mode Bit 7:1 = ADD[7:1] Interface address. These bits define the I2C bus address of the interface. They are not cleared when the interface is disabled (PE=0). 0 FR0 0 0 0 ADD9 ADD8 0 Bit 7:6 = FR[1:0] Frequency bits. These bits are set by software only when the interface is disabled (PE=0). To configure the interface to I2C specified delays select the value corresponding to the microcontroller frequency FCPU. fCPU < 6 MHz 6 to 8 MHz FR1 0 0 FR0 0 1 Bit 0 = ADD0 Address direction bit. This bit is don’t care, the interface acknowledges either 0 or 1. It is not cleared when the interface is disabled (PE=0). Note: Address 01h is always ignored. Bit 5:3 = Reserved 10-bit Addressing Mode Bit 7:0 = ADD[7:0] Interface address. These are the least significant bits of the I2C bus address of the interface. They are not cleared when the interface is disabled (PE=0). Bit 2:1 = ADD[9:8] Interface address. These are the most significant bits of the I2C bus address of the interface (10-bit mode only). They are not cleared when the interface is disabled (PE=0). Bit 0 = Reserved. 126/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx I²C BUS INTERFACE (Cont’d) Table 24. I2C Register Map and Reset Values Address (Hex.) Register Label 7 6 5 4 3 2 1 0 0018h I2CCR Reset Value 0 0 PE 0 ENGC 0 START 0 ACK 0 STOP 0 ITE 0 0019h I2CSR1 Reset Value EVF 0 ADD10 0 TRA 0 BUSY 0 BTF 0 ADSL 0 M/SL 0 SB 0 001Ah I2CSR2 Reset Value 0 0 0 AF 0 STOPF 0 ARLO 0 BERR 0 GCAL 0 001Bh I2CCCR Reset Value FM/SM 0 CC6 0 CC5 0 CC4 0 CC3 0 CC2 0 CC1 0 CC0 0 001Ch I2COAR1 Reset Value ADD7 0 ADD6 0 ADD5 0 ADD4 0 ADD3 0 ADD2 0 ADD1 0 ADD0 0 001Dh I2COAR2 Reset Value FR1 0 FR0 1 0 0 0 ADD9 0 ADD8 0 0 001Eh I2CDR Reset Value MSB 0 0 0 0 0 0 0 LSB 0 127/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 10.8 10-BIT A/D CONVERTER (ADC) 10.8.1 Introduction The on-chip Analog to Digital Converter (ADC) peripheral is a 10-bit, successive approximation converter with internal sample and hold circuitry. This peripheral has up to 16 multiplexed analog input channels (refer to device pin out description) that allow the peripheral to convert the analog voltage levels from up to 16 different sources. The result of the conversion is stored in a 10-bit Data Register. The A/D converter is controlled through a Control/Status Register. 10.8.2 Main Features ■ 10-bit conversion ■ Up to 16 channels with multiplexed input ■ Linear successive approximation ■ Data register (DR) which contains the results ■ Conversion complete status flag ■ On/off bit (to reduce consumption) The block diagram is shown in Figure 69. Figure 69. ADC Block Diagram fCPU DIV 4 0 DIV 2 fADC 1 EOC SPEED ADON 0 CH3 CH2 CH1 CH0 ADCCSR 4 AIN0 AIN1 ANALOG TO DIGITAL ANALOG MUX CONVERTER AINx ADCDRH D9 D8 ADCDRL 128/187 D7 0 D6 0 D5 0 D4 0 D3 0 D2 0 D1 D0 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 10-BIT A/D CONVERTER (ADC) (Cont’d) 10.8.3 Functional Description The conversion is monotonic, meaning that the result never decreases if the analog input does not and never increases if the analog input does not. If the input voltage (VAIN) is greater than VAREF (high-level voltage reference) then the conversion result is FFh in the ADCDRH register and 03h in the ADCDRL register (without overflow indication). If the input voltage (VAIN) is lower than VSSA (lowlevel voltage reference) then the conversion result in the ADCDRH and ADCDRL registers is 00 00h. The A/D converter is linear and the digital result of the conversion is stored in the ADCDRH and ADCDRL registers. The accuracy of the conversion is described in the Electrical Characteristics Section. RAIN is the maximum recommended impedance for an analog input signal. If the impedance is too high, this will result in a loss of accuracy due to leakage and sampling not being completed in the alloted time. 10.8.3.1 A/D Converter Configuration The analog input ports must be configured as input, no pull-up, no interrupt. Refer to the «I/O ports» chapter. Using these pins as analog inputs does not affect the ability of the port to be read as a logic input. In the ADCCSR register: – Select the CS[3:0] bits to assign the analog channel to convert. 10.8.3.2 Starting the Conversion In the ADCCSR register: – Set the ADON bit to enable the A/D converter and to start the conversion. From this time on, the ADC performs a continuous conversion of the selected channel. When a conversion is complete: – The EOC bit is set by hardware. – The result is in the ADCDR registers. A read to the ADCDRH or a write to any bit of the ADCCSR register resets the EOC bit. To read the 10 bits, perform the following steps: 1. Poll the EOC bit 2. Read the ADCDRL register 3. Read the ADCDRH register. This clears EOC automatically. Note: The data is not latched, so both the low and the high data register must be read before the next conversion is complete, so it is recommended to disable interrupts while reading the conversion result. To read only 8 bits, perform the following steps: 1. Poll the EOC bit 2. Read the ADCDRH register. This clears EOC automatically. 10.8.3.3 Changing the conversion channel The application can change channels during conversion. When software modifies the CH[3:0] bits in the ADCCSR register, the current conversion is stopped, the EOC bit is cleared, and the A/D converter starts converting the newly selected channel. 10.8.4 Low Power Modes Note: The A/D converter may be disabled by resetting the ADON bit. This feature allows reduced power consumption when no conversion is needed and between single shot conversions. Mode WAIT HALT Description No effect on A/D Converter A/D Converter disabled. After wakeup from Halt mode, the A/D Converter requires a stabilization time tSTAB (see Electrical Characteristics) before accurate conversions can be performed. 10.8.5 Interrupts None. 129/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 10-BIT A/D CONVERTER (ADC) (Cont’d) 10.8.6 Register Description CONTROL/STATUS REGISTER (ADCCSR) Read/Write (Except bit 7 read only) Reset Value: 0000 0000 (00h) 7 EOC SPEED ADON Bit 3:0 = CH[3:0] Channel Selection These bits are set and cleared by software. They select the analog input to convert. 0 0 CH3 CH2 CH1 CH0 Bit 7 = EOC End of Conversion This bit is set by hardware. It is cleared by hardware when software reads the ADCDRH register or writes to any bit of the ADCCSR register. 0: Conversion is not complete 1: Conversion complete Bit 6 = SPEED ADC clock selection This bit is set and cleared by software. 0: fADC = fCPU/4 1: fADC = fCPU/2 Bit 5 = ADON A/D Converter on This bit is set and cleared by software. 0: Disable ADC and stop conversion 1: Enable ADC and start conversion Bit 4 = Reserved. Must be kept cleared. Channel Pin* CH3 CH2 CH1 CH0 AIN0 AIN1 AIN2 AIN3 AIN4 AIN5 AIN6 AIN7 AIN8 AIN9 AIN10 AIN11 AIN12 AIN13 AIN14 AIN15 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 *The number of channels is device dependent. Refer to the device pinout description. DATA REGISTER (ADCDRH) Read Only Reset Value: 0000 0000 (00h) 7 D9 0 D8 D7 D6 D5 D4 D3 D2 Bit 7:0 = D[9:2] MSB of Converted Analog Value DATA REGISTER (ADCDRL) Read Only Reset Value: 0000 0000 (00h) 7 0 0 0 0 0 0 0 D1 D0 Bit 7:2 = Reserved. Forced by hardware to 0. Bit 1:0 = D[1:0] LSB of Converted Analog Value 130/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 10-BIT A/D CONVERTER (Cont’d) Table 25. ADC Register Map and Reset Values Address (Hex.) Register Label 7 6 5 4 3 2 1 0 0070h ADCCSR Reset Value EOC 0 SPEED 0 ADON 0 0 CH3 0 CH2 0 CH1 0 CH0 0 0071h ADCDRH Reset Value D9 0 D8 0 D7 0 D6 0 D5 0 D4 0 D3 0 D2 0 0072h ADCDRL Reset Value 0 0 0 0 0 0 D1 0 D0 0 131/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx 11 INSTRUCTION SET 11.1 CPU ADDRESSING MODES The CPU features 17 different addressing modes which can be classified in seven main groups: Addressing Mode Example Inherent nop Immediate ld A,#$55 Direct ld A,$55 Indexed ld A,($55,X) Indirect ld A,([$55],X) Relative jrne loop Bit operation bset byte,#5 The CPU Instruction set is designed to minimize the number of bytes required per instruction: To do so, most of the addressing modes may be subdivided in two submodes called long and short: – Long addressing mode is more powerful because it can use the full 64 Kbyte address space, however it uses more bytes and more CPU cycles. – Short addressing mode is less powerful because it can generally only access page zero (0000h 00FFh range), but the instruction size is more compact, and faster. All memory to memory instructions use short addressing modes only (CLR, CPL, NEG, BSET, BRES, BTJT, BTJF, INC, DEC, RLC, RRC, SLL, SRL, SRA, SWAP) The ST7 Assembler optimizes the use of long and short addressing modes. Table 26. CPU Addressing Mode Overview Mode Syntax Destination Pointer Address (Hex.) Pointer Size (Hex.) Length (Bytes) Inherent nop +0 Immediate ld A,#$55 +1 Short Direct ld A,$10 00..FF +1 Long Direct ld A,$1000 0000..FFFF +2 No Offset Direct Indexed ld A,(X) 00..FF +0 Short Direct Indexed ld A,($10,X) 00..1FE +1 Long Direct Indexed ld A,($1000,X) 0000..FFFF +2 Short Indirect ld A,[$10] 00..FF 00..FF byte +2 Long Indirect ld A,[$10.w] 0000..FFFF 00..FF word +2 Short Indirect Indexed ld A,([$10],X) 00..1FE 00..FF byte +2 Long Indirect Indexed ld A,([$10.w],X) 0000..FFFF 00..FF word +2 Relative Direct jrne loop PC+/-127 Relative Indirect jrne [$10] PC+/-127 Bit Direct bset $10,#7 00..FF Bit Indirect bset [$10],#7 00..FF Bit Direct Relative btjt $10,#7,skip 00..FF Bit Indirect Relative btjt [$10],#7,skip 00..FF 132/187 +1 00..FF byte +2 +1 00..FF byte +2 +2 00..FF byte +3 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx INSTRUCTION SET OVERVIEW (Cont’d) 11.1.1 Inherent All Inherent instructions consist of a single byte. The opcode fully specifies all the required information for the CPU to process the operation. Inherent Instruction Function NOP No operation TRAP S/W Interrupt WFI Wait For Interrupt (Low Power Mode) HALT Halt Oscillator (Lowest Power Mode) RET Sub-routine Return IRET Interrupt Sub-routine Return SIM Set Interrupt Mask (level 3) RIM Reset Interrupt Mask (level 0) SCF Set Carry Flag RCF Reset Carry Flag RSP Reset Stack Pointer LD Load CLR Clear PUSH/POP Push/Pop to/from the stack INC/DEC Increment/Decrement TNZ Test Negative or Zero CPL, NEG 1 or 2 Complement MUL Byte Multiplication SLL, SRL, SRA, RLC, RRC Shift and Rotate Operations SWAP Swap Nibbles 11.1.2 Immediate Immediate instructions have 2 bytes, the first byte contains the opcode, the second byte contains the operand value. Immediate Instruction Function LD Load CP Compare BCP Bit Compare AND, OR, XOR Logical Operations ADC, ADD, SUB, SBC Arithmetic Operations 11.1.3 Direct In Direct instructions, the operands are referenced by their memory address. The direct addressing mode consists of two submodes: Direct (short) The address is a byte, thus requires only one byte after the opcode, but only allows 00 - FF addressing space. Direct (long) The address is a word, thus allowing 64 Kbyte addressing space, but requires 2 bytes after the opcode. 11.1.4 Indexed (No Offset, Short, Long) In this mode, the operand is referenced by its memory address, which is defined by the unsigned addition of an index register (X or Y) with an offset. The indirect addressing mode consists of three submodes: Indexed (No Offset) There is no offset, (no extra byte after the opcode), and allows 00 - FF addressing space. Indexed (Short) The offset is a byte, thus requires only one byte after the opcode and allows 00 - 1FE addressing space. Indexed (long) The offset is a word, thus allowing 64 Kbyte addressing space and requires 2 bytes after the opcode. 11.1.5 Indirect (Short, Long) The required data byte to do the operation is found by its memory address, located in memory (pointer). The pointer address follows the opcode. The indirect addressing mode consists of two submodes: Indirect (short) The pointer address is a byte, the pointer size is a byte, thus allowing 00 - FF addressing space, and requires 1 byte after the opcode. Indirect (long) The pointer address is a byte, the pointer size is a word, thus allowing 64 Kbyte addressing space, and requires 1 byte after the opcode. 133/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx INSTRUCTION SET OVERVIEW (Cont’d) 11.1.6 Indirect Indexed (Short, Long) This is a combination of indirect and short indexed addressing modes. The operand is referenced by its memory address, which is defined by the unsigned addition of an index register value (X or Y) with a pointer value located in memory. The pointer address follows the opcode. The indirect indexed addressing mode consists of two submodes: Indirect Indexed (Short) The pointer address is a byte, the pointer size is a byte, thus allowing 00 - 1FE addressing space, and requires 1 byte after the opcode. Indirect Indexed (Long) The pointer address is a byte, the pointer size is a word, thus allowing 64 Kbyte addressing space, and requires 1 byte after the opcode. Table 27. Instructions Supporting Direct, Indexed, Indirect and Indirect Indexed Addressing Modes Long and Short Instructions LD Function Load CP Compare AND, OR, XOR Logical Operations ADC, ADD, SUB, SBC Arithmetic Additions/Substractions operations BCP Bit Compare Short Instructions Only Function CLR Clear INC, DEC Increment/Decrement TNZ Test Negative or Zero CPL, NEG 1 or 2 Complement BSET, BRES Bit Operations BTJT, BTJF Bit Test and Jump Operations SLL, SRL, SRA, RLC, RRC Shift and Rotate Operations SWAP Swap Nibbles CALL, JP Call or Jump subroutine 134/187 11.1.7 Relative mode (Direct, Indirect) This addressing mode is used to modify the PC register value, by adding an 8-bit signed offset to it. Available Relative Direct/Indirect Instructions Function JRxx Conditional Jump CALLR Call Relative The relative addressing mode consists of two submodes: Relative (Direct) The offset is following the opcode. Relative (Indirect) The offset is defined in memory, which address follows the opcode. ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx INSTRUCTION SET OVERVIEW (Cont’d) 11.2 INSTRUCTION GROUPS The ST7 family devices use an Instruction Set consisting of 63 instructions. The instructions may Load and Transfer LD CLR Stack operation PUSH POP be subdivided into 13 main groups as illustrated in the following table: RSP Increment/Decrement INC DEC Compare and Tests CP TNZ BCP Logical operations AND OR XOR CPL NEG Bit Operation BSET BRES Conditional Bit Test and Branch BTJT BTJF Arithmetic operations ADC ADD SUB SBC MUL Shift and Rotates SLL SRL SRA RLC RRC SWAP SLA Unconditional Jump or Call JRA JRT JRF JP CALL CALLR NOP Conditional Branch JRxx Interruption management TRAP WFI HALT IRET Condition Code Flag modification SIM RIM SCF RCF Using a prebyte The instructions are described with one to four opcodes. In order to extend the number of available opcodes for an 8-bit CPU (256 opcodes), three different prebyte opcodes are defined. These prebytes modify the meaning of the instruction they precede. The whole instruction becomes: PC-2 End of previous instruction PC-1 Prebyte PC Opcode PC+1 Additional word (0 to 2) according to the number of bytes required to compute the effective address RET These prebytes enable instruction in Y as well as indirect addressing modes to be implemented. They precede the opcode of the instruction in X or the instruction using direct addressing mode. The prebytes are: PDY 90 Replace an X based instruction using immediate, direct, indexed, or inherent addressing mode by a Y one. PIX 92 Replace an instruction using direct, direct bit, or direct relative addressing mode to an instruction using the corresponding indirect addressing mode. It also changes an instruction using X indexed addressing mode to an instruction using indirect X indexed addressing mode. PIY 91 Replace an instruction using X indirect indexed addressing mode by a Y one. 135/187 ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx INSTRUCTION SET OVERVIEW (Cont’d) Mnemo Description Function/Example Dst Src I1 H I0 N Z C ADC Add with Carry A=A+M+C A M H N Z C ADD Addition A=A+M A M H N Z C AND Logical And A=A.M A M N Z BCP Bit compare A, Memory tst (A . M) A M N Z BRES Bit Reset bres Byte, #3 M BSET Bit Set bset Byte, #3 M BTJF Jump if bit is false (0) btjf Byte, #3, Jmp1 M C BTJT Jump if bit is true (1) btjt Byte, #3, Jmp1 M C CALL Call subroutine CALLR Call subroutine relative CLR Clear CP Arithmetic Compare tst(Reg - M) reg CPL One Complement A = FFH-A DEC Decrement dec Y HALT Halt IRET Interrupt routine return Pop CC, A, X, PC INC Increment inc X JP Absolute Jump jp [TBL.w] JRA Jump relative always JRT Jump relative JRF Never jump jrf * JRIH Jump if ext. INT pin = 1 (ext. INT pin high) JRIL Jump if ext. INT pin = 0 (ext. INT pin low) JRH Jump if H = 1 H=1? JRNH Jump if H = 0 H=0? JRM Jump if I1:0 = 11 I1:0 = 11 ? JRNM Jump if I1:0 11 I1:0 11 ? JRMI Jump if N = 1 (minus) N=1? JRPL Jump if N = 0 (plus) N=0? reg, M 1 N Z C reg, M N Z 1 reg, M N Z N Z N Z M 1 JREQ Jump if Z = 1 (equal) Z=1? JRNE Jump if Z = 0 (not equal) Z=0? JRC Jump if C = 1 C=1? JRNC Jump if C = 0 C=0? JRULT Jump if C = 1 Unsigned < JRUGE Jump if C = 0 Jmp if unsigned >= JRUGT Jump if (C + Z = 0) Unsigned > 136/187 0 I1 reg, M 0 H I0 C ST72321BRx, ST72321BARx ST72321BJx, ST72321BKx INSTRUCTION SET OVERVIEW (Cont’d) Mnemo Description Function/Example Dst Src JRULE Jump if (C + Z = 1) Unsigned