ST72260Gx, ST72262Gx, ST72264Gx
8-BIT MCU WITH FLASH OR ROM MEMORY, ADC, TWO 16-BIT TIMERS, I2C, SPI, SCI INTERFACES
Memories 4 K or 8 Kbytes Program memory: ROM or Single voltage extended Flash (XFlash) with read-out protection write protection and InCircuit Programming and In-Application Programming (ICP and IAP). 10K write/erase cycles guaranteed, data retention: 20 years at 55C. 256 bytes RAM Clock, Reset and Supply Management Enhanced reset system Enhanced low voltage supply supervisor (LVD) with 3 programmable levels and auxiliary voltage detector (AVD) with interrupt capability for implementing safe power-down procedures Clock sources: crystal/ceramic resonator oscillators, internal RC oscillator and bypass for external clock PLL for 2x frequency multiplication Clock-out capability 4 Power Saving Modes: Halt, Active Halt,Wait and Slow Interrupt Management Nested interrupt controller 10 interrupt vectors plus TRAP and RESET 22 external interrupt lines (on 2 vectors) 22 I/O Ports 22 multifunctional bidirectional I/O lines 20 alternate function lines 8 high sink outputs 4 Timers Main Clock Controller with Real time base and Clock-out capabilities Configurable watchdog timer
SDIP32
LFBGA 6x6mm
SO28
Two 16-bit timers with: 2 input captures, 2 output compares, external clock input on one timer, PWM and Pulse generator modes 3 Communication Interfaces SPI synchronous serial interface I2C multimaster interface (SMBus V1.1 Compliant) SCI asynchronous serial interface 1 Analog peripheral 10-bit ADC with 6 input channels Instruction Set 8-bit data manipulation 63 basic instructions with illegal opcode detection 17 main addressing modes 8 x 8 unsigned multiply instruction Development Tools Full hardware/software development package
Device Summary
Features Program memory - bytes RAM (stack) - bytes Peripherals Operating Supply CPU Frequency Operating Temperature Packages
ST72260G1
4K Watchdog timer, RTC, Two16-bit timers, SPI
ST72262G 1 ST72262G 2 ST72264G1
4K 8K
ST72264G 2
4K 8K 256 (128) Watchdog timer, RTC, Watchdog timer, RTC, Two 16-bit timers, SPI, ADC Two 16-bit timers, SPI, SCI, I2C, ADC 2.7 V to 5.5 V Up to 8 MHz (with oscillator up to 16 MHz) PLL 4/8 MHz 0 C to +70 C / -40 C to +85 C -40 C to +85 C -40 C to +85 C SO28 / SDIP32 SO28 / SDIP32 LFBGA
Rev. 3
June 2005 1/172
1
Table of Contents
1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 PIN DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 REGISTER & MEMORY MAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4 FLASH PROGRAM MEMORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.2 4.3 4.4 4.5 4.6 4.7 MAIN FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 PROGRAMMING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 ICC INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 MEMORY PROTECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 RELATED DOCUMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 REGISTER DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5 CENTRAL PROCESSING UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5.2 5.3 MAIN FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 CPU REGISTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6 SUPPLY, RESET AND CLOCK MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 6.1 PHASE LOCKED LOOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 6.2 6.3 6.4 MULTI-OSCILLATOR (MO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 RESET SEQUENCE MANAGER (RSM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 SYSTEM INTEGRITY MANAGEMENT (SI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7 INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 7.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 7.2 7.3 7.4 7.5 MASKING AND PROCESSING FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 INTERRUPTS AND LOW POWER MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 CONCURRENT & NESTED MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 INTERRUPT REGISTER DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
8 POWER SAVING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 8.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 8.2 8.3 8.4 8.5 SLOW MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 WAIT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 ACTIVE-HALT AND HALT MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 HALT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
9 I/O PORTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 9.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 9.2 9.3 9.4 9.5 9.6 9.7 9.8 FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 I/O PORT IMPLEMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 UNUSED I/O PINS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 LOW POWER MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 DEVICE-SPECIFIC I/O PORT CONFIGURATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 172 I/O PORT REGISTER DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
10 MISCELLANEOUS REGISTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
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10.1 I/O PORT INTERRUPT SENSITIVITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 10.2 I/O PORT ALTERNATE FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 10.3 MISCELLANEOUS REGISTER DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 11 ON-CHIP PERIPHERALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 11.1 WATCHDOG TIMER (WDG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 11.2 MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK (MCC/RTC) . . . . . . . . . . . . . 53 11.3 16-BIT TIMER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 11.4 SERIAL PERIPHERAL INTERFACE (SPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 11.5 SERIAL COMMUNICATIONS INTERFACE (SCI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 11.6 I2C BUS INTERFACE (I2C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 11.7 10-BIT A/D CONVERTER (ADC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 12 INSTRUCTION SET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 12.1 CPU ADDRESSING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 12.2 INSTRUCTION GROUPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 13 ELECTRICAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 13.1 PARAMETER CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 13.2 ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 13.3 OPERATING CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 13.4 SUPPLY CURRENT CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 13.5 CLOCK AND TIMING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 13.6 MEMORY CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 13.7 EMC CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 13.8 I/O PORT PIN CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 13.9 CONTROL PIN CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 13.10 TIMER PERIPHERAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 13.11 COMMUNICATION INTERFACE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . 153 13.12 10-BIT ADC CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 14 PACKAGE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 14.1 PACKAGE MECHANICAL DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 14.2 THERMAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 14.3 LEAD-FREE PACKAGE INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 15 DEVICE CONFIGURATION AND ORDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . 162 15.1 OPTION BYTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 15.2 DEVICE ORDERING INFORMATION AND TRANSFER OF CUSTOMER CODE . . . . 164 15.3 DEVELOPMENT TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 16 KNOWN LIMITATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 16.1 ALL FLASH AND ROM DEVICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 16.2 FLASH DEVICES ONLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 17 REVISION HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
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To obtain the most recent version of this datasheet, please check at www.st.com>products>technical literature>datasheet Please note that the list of known limitations can be found at the end of this document on page 168.
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1 INTRODUCTION
The ST72260Gx, ST72262Gx and ST72264Gx devices are members of the ST7 microcontroller family. They can be grouped as follows : ST72264Gx devices are designed for mid-range applications with ADC, I2C and SCI interface capabilities . ST72262Gx devices target the same range of applications but without I2C interface or SCI. ST72260Gx devices are for applications that do not need ADC, I2C peripherals or SCI. All devices are based on a common industrystandard 8-bit core, featuring an enhanced instruction set. The ST72F260G, ST72F262G, and ST72F264G versions feature single-voltage FLASH memory with byte-by-byte In-Circuit Programming (ICP) capabilities. Figure 1. General Block Diagram
Internal CLOCK OSC1 OSC2 MCC/RTC LVD VDD VSS RESET POWER SUPPLY CONTROL 8-BIT CORE ALU PROGRAM MEMORY (4 or 8K Bytes) ICD
ADDRESS AND DATA BUS
Under software control, all devices can be placed in WAIT, SLOW, Active-HALT or HALT mode, reducing power consumption when the application is in idle or stand-by state. The enhanced instruction set and addressing modes of the ST7 offer both power and flexibility to software developers, enabling the design of highly efficient and compact application code. In addition to standard 8-bit data management, all ST7 microcontrollers feature true bit manipulation, 8x8 unsigned multiplication and indirect addressing modes. For easy reference, all parametric data is located in Section 13 on page 126. Related Documentation AN1365: Guidelines for migrating ST72C254 applications to ST72F264
I2C* SCI* PORT A PA7:0 (8 bits)
MULTI OSC
SPI PORT B 16-BIT TIMER A PORT C 10-BIT ADC* 16-BIT TIMER B WATCHDOG PB7:0 (8 bits)
PC5:0 (6 bits)
RAM (256 Bytes)
*Not available on some devices, see device summary on page 1.
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2 PIN DESCRIPTION
Figure 2. 28-Pin SO Package Pinout
RE SET O SC1 O SC2 SS/ P B 7 SCK/PB6 MISO/PB5 MO SI/PB4 OC MP2_A/PB3 ICAP2_A/PB2 OC MP1_A/PB1 ICAP1_A/PB0 AIN5/EXTCLK_A/PC5 A I N 4 2 /OC MP2_B/PC4 AIN3 2 /ICAP2_B/PC3
1 2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 ei0 or ei11 ei1 ei0
28 27 26 25 24 23 22 21 20 19 18 17 16 15
VDD VS S ICCSEL PA0 (HS)/ICCCLK PA1 (HS)/ICCDATA PA2 (HS) PA3 (HS) PA4 (HS)/SCLI3 PA5(HS)/RDI3 PA6 (HS)/SDAI3 PA7 (HS)/TDO3 PC 0/ICAP1_B/A IN0 2 PC1/OCMP1_B/AIN12 PC2/MCO/AIN22
(HS) 20mA high sink capability eiX associated external interrupt vector
Configurable by option byte Alternate function not available on ST72260 3 Alternate function not available on ST72260 and ST72262
Figure 3. 32-Pin SDIP Package Pinout
R ESET O SC1 O SC2 SS/ P B 7 SCK/PB6 MISO/PB5 MO SI/PB4 NC NC O CMP2_A/PB3 ICAP2_A/PB2 O CMP1_A/PB1 ICAP1_A/PB0 AIN5 2 / E X T C L K _ A / P C 5 AIN42/OCMP2_B/PC4 AIN32/ICAP2_B/PC3
1 2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ei0 or ei11 ei1 ei0 ei1 ei0
32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17
VDD VS S ICCSEL PA0 (HS)/ICCCLK PA1 (HS)/ICCDATA PA2 (HS) PA3 (HS) NC NC PA4 (HS)/SCLI3 PA5 (HS)/RDI3 PA6 (HSI/SDAI3 PA7 (HS)/TDO3 PC 0/ICAP1_B/AIN02 PC 1/OC MP1_B/AIN1 2 PC 2/MC O/AIN22
(HS) 20mA high sink capability eiX associated external interrupt vector
Configurable by option byte Alternate function not available on ST72260 3 Alternate function not available on ST72260 and ST72262
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PIN DESCRIPTION (Cont'd) Figure 4. TFBGA Package Pinout (view through package) 1 2 3 4 5 6
A B C D E F
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PIN DESCRIPTION (Cont'd) For external pin connection guidelines, refer to Section 13 "ELECTRICAL CHARACTERISTICS" on page 126. Legend / Abbreviations for Table 1: Type: I = input, O = output, S = supply Input level: A = Dedicated analog input In/Output level: CT= CMOS 0.3 VDD/0.7 VDD with input trigger Output level: HS = 20 mA 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 Section 9 "I/O PORTS" on page 38 for more details on the software configuration of the I/O ports. The RESET configuration of each pin is shown in bold. This configuration is valid as long as the device is in reset state. Table 1. Device Pin Description
Pin n Type SDIP 32 S O2 8 BGA Pin Name Level Output Input Port / Control Input float wpu ana int Main Output Function (after reset) OD PP X
Alternate Function
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7
A3 RESET C4 OSC1 3) B3 OSC2 3) A2 PB7/SS A1 PB6/SCK B1 PB5/MISO B2 PB4/MOSI C1 NC C2 NC D1 NC
I/O CT I O I/O I/O I/O I/O CT CT CT CT X X X X
X
Top priority non maskable interrupt (active low) External clock input or Resonator oscillator inverter input or resistor input for RC oscillator Resonator oscillator inverter output or capacitor input for RC oscillator X X X X Port B7 Port B6 Port B5 Port B4 SPI Slave Select (active low) SPI Serial Clock SPI Master In/ Slave Out Data SPI Master Out / Slave In Data
ei1 ei1 ei1 ei1
X X X X
Not Connected
10 11
8 9
C3 PB3/OCMP2_A D2 PB2/ICAP2_A
I/O I/O
CT CT CT
X X
ei1 ei1
X X
X X
Port B3 Port B2
Timer A Output Compare 2 Timer A Input Capture 2 Timer A Output Compare 1
12
10 E1 PB1 /OCMP1_A
I/O
X
ei1
X
Caution: Negative current X Port B1 injection not allowed on this pin4).
Timer A Input Capture 1
13
11 F1 PB0 /ICAP1_A
I/O
CT
X
ei1
X
Caution: Negative current X Port B0 injection not allowed on this pin4).
X Port C5 Timer A Input Clock or ADC Analog Input 5
14
12 F2 PC5/EXTCLK_A/AIN5 I/O
CT
X ei0/ei1 X
X
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Pin n Type SDIP32 SO28 BG A Pin Name
Level O u tput Input
Port / Control Input float wpu ana int
OD
PP
Main Output Function (after reset) X X X X X X T X T X X X X X X X Port C4 Port C3 Port C2 Port C1 Port C0 Port A7 Port A6 Port A5 Port A4
Alternate Function
15 16 17 18 19 20 21 22 23 24 25
13 E2 PC4/OCMP2_B/AIN4 14 F3 PC3/ ICAP2_B/AIN3 15 E3 PC2/MCO/AIN2 16 F4 PC1/OCMP1_B/AIN1 17 D3 PC0/ICAP1_B/AIN0 18 E4 PA7/TDO 19 F5 PA6/SDAI 20 F6 PA5 /RDI 21 E6 PA4/SCLI E5 NC D6 NC D5 NC
I/O I/O I/O I/O I/O
CT CT CT CT CT
X ei0/ei1 X X ei0/ei1 X X ei0/ei1 X X ei0/ei1 X X ei0/ei1 X X X X X ei0 ei0 ei0 ei0
Timer B Output Compare 2 or ADC Analog Input 4 Timer B Input Capture 2 or ADC Analog Input 3 Main clock output (fCPU) or ADC Analog Input 2 Timer B Output Compare 1 or ADC Analog Input 1 Timer B Input Capture 1 or ADC Analog Input 0 SCI output I2C DATA SCI input I2C CLOCK
I/O CT HS I/O CT HS I/O C T HS I/O CT HS
Not Connected
26 27
22 C6 PA3 23 D4 PA2 C5 NC
I/O CT HS I/O CT HS
X X
ei0 ei0
X X
X X
Port A3 Port A2
Not Connected B6 NC 28 29 30 31 32 24 A6 PA1/ICCDATA 25 A5 PA0/ICCCLK 26 B5 ICCSEL 27 A4 VSS 28 B4 VDD I/O C T H S I/O CT HS I S S CT X X X ei0 ei0 X X X X Port A1 Port A0 In Circuit Communication Data In Circuit Communication Clock
ICC mode pin, must be tied low Ground Main power supply
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 a pull-up interrupt input, otherwise the configuration is a floating interrupt input. Port C is mapped to ei0 or ei1 by option byte. 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 Section 9 "I/O PORTS" on page 38 for more details. 3. OSC1 and OSC2 pins connect a crystal or ceramic resonator, or an external source to the on-chip oscillator see Section 2 "PIN DESCRIPTION" on page 6 and Section 6.2 "MULTI-OSCILLATOR (MO)" on page 21 for more details. 4: For details refer to Section 13.8 on page 144
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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 location, 256 bytes of RAM and up to 8 Kbytes of user program memory. The RAM space includes up to 128 bytes for the stack from 0100h to 017Fh. The highest address bytes contain the user reset and interrupt vectors. The Flash memory contains two sectors (see Figure 5) mapped in the upper part of the ST7 adFigure 5. Memory Map dressing space so the reset and interrupt vectors are located in Sector 0 (F000h-FFFFh). The size of Flash Sector 0 and other device options are configurable by Option byte (refer to Section 15.1 on page 162). 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
0000h 007Fh 0080h
HW Registers (see Table 2)
0080h
RAM (256 Bytes)
017Fh 0180h
00FFh 0100h
Short Addressing RAM Zero page (128 Bytes) Stack or 16-bit Addressing RAM (128 Bytes)
8K FLASH PROGRAM MEMORY
017Fh
Reserved
DFFFh E000h
E000h
Program Memory (4K, 8 KBytes)
FFDFh FFE0h FFFFh
EFFFh F000h FFFFh
4 Kbytes SECTOR 1 4 Kbytes SECTOR 0
Interrupt & Reset Vectors (see Table 5 on page 32)
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Table 2. Hardware Register Map
Address 0000h 0001h 0002h 0003h 0004h 0005h 0006h 0007h 0008h 0009h 000Ah 000Bh to 001Bh 001Ch 001Dh 001Eh 001Fh 0020h 0021h 0022h 0023h 0024h 0025h 0026h 0027h 0028h 0029h 002Ah 002Bh 002Ch 002Dh 002Eh 002Fh 0030h I2CCR I2CSR 1 I2CSR 2 I2CCC R I2CO AR1 I2CO AR2 I2CDR I2C MC C SPI W ATCHDOG ITC ISPR 0 ISPR 1 ISPR 2 ISPR 3 MIS CR1 SPID R SPIC R SPIC S R WD G C R SICS R MC C S R PADR PADDR PAOR Port B PBDR PBDDR PBOR Block Register Label PCDR PCDDR PCOR Register Name Port C Data Register Port C Data Direction Register Port C Option Register Reserved (1 Byte) Port B Data Register Port B Data Direction Register Port B Option Register Reserved (1 Byte) Port A Data Register Port A Data Direction Register Port A Option Register 00h 1) 00h 00h R/W R/W R/W 00h 1) 00h 00h R/W R/W R/W. Reset Status Remarks
Port C
xx0 0 00h1) R/W 2) 00h R/W 2) R/W 2) 00h
Port A
Reserved (17 Bytes) Interrupt software priority register0 Interrupt software priority register1 Interrupt software priority register2 Interrupt software priority register3 Miscellanous register 1 SPI Data I/O Register SPI Control Register SPI Status Register Watchdog Control Register System Integrity Control / Status Register Main Clock Control / Status Register Reserved (1 Byte) 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 Reserved (2 Bytes) 00h 00h 00h 00h 00h 40h 00h R/W Read Only Read Only R/W R/W R/W R/W FFh FFh FFh FFh 00h xxh 0xh 00h 7Fh 000x 000x 00h R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W
I2C
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Address 0031h 0032h 0033h 0034h 0035h 0036h 0037h 0038h 0039h 003Ah 003Bh 003Ch 003Dh 003Eh 003Fh 0040h 0041h 0042h 0043h 0044h 0045h 0046h 0047h 0048h 0049h 004Ah 004Bh 004Ch 004Dh 004Eh 004Fh 0050h 0051h 0052h 0053h 0054h 0055h 0056h 0057h to 006Eh 006Fh 0070h 0071h 0072h 0073h to 007Fh
Block
Register Label TACR2 TACR1 TASCSR TAIC1HR TAIC1LR TAOC1HR TAOC1LR TACHR TACLR TAACHR TAACLR TAIC2HR TAIC2LR TAOC2HR TAOC2LR MIS CR2 TBCR2 TBCR1 TBSCSR TBIC1HR TBIC1LR TBOC1HR TBOC1LR TBCHR TBCLR TBACHR TBACLR TBIC2HR TBIC2LR TBOC2HR TBOC2LR SCISR SCIDR SCIB RR SCIC R1 SCIC R2 SCIE RPR SCIE TPR
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 Miscellanous register 2 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 SCI Status Register SCI Data Register SCI Baud Rate Register SCI Control Register1 SCI Control Register2 SCI Extended Receive Prescaler Register SCI Extended Transmit Prescaler Register Reserved (24 Bytes)
Reset Status 00h 00h xxh xxh xxh 80h 00h FFh FCh FFh FCh xxh xxh 80h 00h 00h 00h 00h xxh xxh xxh 80h 00h FFh FCh FFh FCh xxh xxh 80h 00h C0h xxh 00h x000 0000h 00h 00h 00h
Remarks R/W R/W R/W Read Only Read Only R/W R/W Read Only Read Only Read Only Read Only Read Only Read Only R/W R/W R/W R/W R/W R/W Read Only Read Only R/W R/W Read Only Read Only Read Only Read Only Read Only Read Only R/W R/W Read Only R/W R/W R/W R/W R/W R/W
TIMER A
TIMER B
SCI
ADC FLASH
ADCDRL ADCDRH ADCCSR FCSR
Data Register Low3) Data Register High3) Control/Status Register Flash Control Register Reserved (13 Bytes)
00h 00h 00h 00h
Read Only Read Only R/W R/W
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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. 3. For compatibility with the ST72C254, the ADCDRL and ADCDRH data registers are located with the LSB on the lower address (6Fh) and the MSB on the higher address (70h). As this scheme is not little Endian, the ADC data registers cannot be treated by C programs as an integer, but have to be treated as two char registers.
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4 FLASH PROGRAM MEMORY
4.1 Introduction The ST7 single voltage extended Flash (XFlash) is a non-volatile memory that can be electrically erased and programmed either on a byte-by-byte basis or up to 32 bytes in parallel. The XFlash devices can be programmed off-board (plugged in a programming tool) or on-board using In-Circuit Programming or In-Application Programming. The array matrix organisation allows each sector to be erased and reprogrammed without affecting other sectors. 4.2 Main Features
ICP (In-Circuit Programming) IAP (In-Application Programming) ICT (In-Circuit Testing) for downloading and executing user application test patterns in RAM Sector 0 size configurable by option byte Read-out and write protection against piracy
4.3 PROGRAMMING MODES The ST7 can be programmed in three different ways: Insertion in a programming tool. In this mode, FLASH sectors 0 and 1 and option byte row can be programmed or erased. In-Circuit Programming. In this mode, FLASH sectors 0 and 1 and option byte row can be programmed or erased without removing the device from the application board. In-Application Programming. In this mode, sector 1 can be programmed or erased without removing the device from the application
board and while the application is running. 4.3.1 In-Circuit Programming (ICP) ICP uses a protocol called ICC (In-Circuit Communication) which allows an ST7 plugged on a printed circuit board (PCB) to communicate with an external programming device connected via cable. ICP is performed in three steps: Switch the ST7 to ICC mode (In-Circuit Communications). This is done by driving a specific signal sequence on the ICCCLK/DATA pins while the RESET pin is pulled low. When the ST7 enters ICC mode, it fetches a specific RESET vector which points to the ST7 System Memory containing the ICC protocol routine. This routine enables the ST7 to receive bytes from the ICC interface. Download ICP Driver code in RAM from the ICCDATA pin Execute ICP Driver code in RAM to program the FLASH memory Depending on the ICP Driver code downloaded in RAM, FLASH memory programming can be fully customized (number of bytes to program, program locations, or selection of the serial communication interface for downloading). 4.3.2 In Application Programming (IAP) This mode uses an IAP Driver program previously programmed in Sector 0 by the user (in ICP mode). 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.) IAP mode can be used to program any memory areas except Sector 0, which is write/erase protected to allow recovery in case errors occur during the programming operation.
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FLASH PROGRAM MEMORY (Cont'd) 4.4 ICC interface ICP needs a minimum of 4 and up to 7 pins to be connected to the programming tool. These pins are: RESET: device reset VSS: device power supply ground ICCCLK: ICC output serial clock pin ICCDATA: ICC input serial data pin ICCSEL: ICC selection (not required on devices without ICCSEL pin) OSC1: main clock input for external source (not required on devices without OSC1/OSC2 pins) VDD: application board power supply (optional, see Note 3) 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 be implemented in case another device forces the signal. Refer to the Programming Figure 6. Typical ICC Interface
PROGRAMMING TOOL ICC CONNECTOR ICC Cable ICC CONNECTOR HE10 CONNECTOR TYPE OPTIONAL (See Note 4) APPLICATION BOARD
Tool documentation for recommended resistor values. 2. During the ICP 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 resistor<1K). A schottky diode can be used to isolate the application RESET circuit in this case. When using a classical RC network with R>1K or a reset management IC with open drain output and pull-up resistor>1K, no additional components are needed. In all cases the user must ensure that no external reset is generated by the application during the ICC session. 3. The use of Pin 7 of the ICC connector depends on the Programming Tool architecture. This pin must be connected when using most ST Programming Tools (it is used to monitor the application power supply). Please refer to the Programming Tool manual. 4. Pin 9 has to be connected to the OSC1 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.
(See Note 3)
9 10
7 8
5 6
3 4
1 2
APPLICATION RESET SOURCE See Note 2 10k APPLICATION POWER SUPPLY CL2 CL1 See Note 1 APPLICATION I/O VSS ICCSEL RESET ICCDATA ICCCLK
VDD
OSC2
OSC1 ST7
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FLASH PROGRAM MEMORY (Cont'd) 4.5 Memory Protection There are two different types of memory protection: Read Out Protection and Write/Erase Protection which can be applied individually. 4.5.1 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 program memory is 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. 4.5.2 Flash Write/Erase Protection Write/erase protection, when set, makes it impossible to both overwrite and erase program memory. Its purpose is to provide advanced security to applications and prevent any change being made to the memory content. Warning: Once set, Write/erase protection can never be removed. A write-protected flash device is no longer reprogrammable. Write/erase protection is enabled through the FMP_W bit in the option byte. 4.6 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. AN1477: Emulated data EEPROM with XFlash memory AN1576: IAP drivers for ST7 HDFlash or XFlash MCUs AN1575: On Board Programming methods for ST7 HDFlash or XFlash MCUs AN1070: Checksum self checking capability 4.7 Register Description FLASH CONTROL/STATUS REGISTER (FCSR) Read / Write Reset Value: 000 0000 (00h) 1st RASS Key: 0101 0110 (56h) 2nd RASS Key: 1010 1110 (AEh)
7 0 0 0 0 0 OPT LAT 0 PGM
Note: This register is reserved for programming using ICP, IAP or other programming methods. It controls the XFlash programming and erasing operations. When an EPB or another programming tool is used (in socket or ICP mode), the RASS keys are sent automatically.
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5 CENTRAL PROCESSING UNIT
5.1 INTRODUCTION This CPU has a full 8-bit architecture and contains six internal registers allowing efficient 8-bit data manipulation. 5.2 MAIN FEATURES
5.3 CPU REGISTERS The 6 CPU registers shown in Figure 7 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).
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 7. CPU Registers
7 RESET VALUE = XXh 7 RESET VALUE = XXh 7 RESET VALUE = XXh 15 PCH 87 PCL 0 PROGRAM COUNTER RESET VALUE = RESET VECTOR @ FFFEh-FFFFh 7 0 CONDITION CODE REGISTER 1 1 I1 H I0 N Z C RESET VALUE = 1 1 1 X 1 X X X 15 87 0 STACK POINTER RESET VALUE = STACK HIGHER ADDRESS X = Undefined Value 0 Y INDEX REGISTER 0 X INDEX REGISTER 0 ACCUMULATOR
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CENTRAL PROCESSING UNIT (Cont'd) Condition Code Register (CC) Read/Write Reset Value: 111x1xxx
7
1 1 I1 H I0 N Z
Bit 1 = Z Zero. 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 inst ructions. 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
0 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 (i.e. the most significant bit is a logic 1). This bit is accessed by the JRMI and JRPL instructions.
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.
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CENTRAL PROCESSING UNIT (Cont'd) Stack Pointer (SP) Read/Write Reset Value: 01 7Fh
15 0 7
SP7 SP6 SP5 SP4 SP3 SP2 SP1
8 0 0 0 0 0 0 1 0 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 8). Since the stack is 128 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. Figure 8. Stack Manipulation Example
CALL Subroutine @ 0100h Interrupt Event P USH Y
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 8 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.
PO P Y
IRET
RET or RSP
SP SP CC A X PC H SP PCH @ 017Fh PCL P CL PCH PCL Y CC A X PCH PCL PCH PC L SP CC A X PCH PCL PCH PCL SP PCH PCL SP
Stack Higher Address = 017Fh Stack Lower Address = 0100h
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6 SUPPLY, RESET AND CLOCK MANAGEMENT
The device includes a range of utility features for securing the application in critical situations (for example in case of a power brown-out), and reducing the number of external components. An overview is shown in Figure 10. For more details, refer to dedicated parametric section. Main Features Optional PLL for multiplying the frequency by 2 (not to be used with internal RC oscillator) Reset Sequence Manager (RSM) Multi-Oscillator Clock Management (MO) 4 Crystal/Ceramic resonator oscillators 1 Internal RC oscillator System Integrity Management (SI) Main supply Low Voltage Detector (LVD) Auxiliary Voltage Detector (AVD) with interrupt capability for monitoring the main supply
6.1 PHASE LOCKED LOOP If the clock frequency input to the PLL is in the 2 to 4 MHz range, 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 139. Figure 9. PLL Block Diagram
PLL x 2
fOSC
0 fOSC2 1
/2
PLL OPTION BIT
Figure 10. Clock, Reset and Supply Block Diagram
MISCR1 Register SLOW MODE SELECTION MULTIOSCILLATOR OSC1 (MO) SYSTEM INTEGRITY MANAGEMENT RESET SEQUENCE RESET MANAGER (RSM) WATCHDOG AVD Interrupt Request SICSR 0 AVD AVD LVD F RF IE WDG RF TIMER (WDG) 0 MAIN CLOCK CONTROLLER WITH REALTIME CLOCK (MCC/RTC)
f CPU to CPU and Peripherals
OSC2
fOSC
PLL (option)
fOSC2
0
0
LOW VOLTAGE VSS VDD DETECTOR (LVD)
AUXILIARY VOLTAGE DETECTOR (AVD)
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6.2 MULTI-OSCILLATOR (MO) The main clock of the ST7 can be generated by four different source types coming from the multioscillator block: an external source 5 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 3. 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 Effects 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. 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 5 oscillators with different frequency ranges has to be done by option byte in order to reduce consumption (refer to Section 15.1 on page 162 for more details on the frequency ranges). In this mode of the multioscillator, the resonator and the load capacitors have to be placed as close as possible to the oscillator pins in order to minimize output distortion and start-up stabilization time. The loading capacitance values must be adjusted according to the selected oscillator. These oscillators are not stopped during the RESET phase to avoid losing time in the oscillator start-up phase. 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. Related documentation AN1530: Accurate timebase for low cost ST7 applications with internal RC. Table 3. ST7 Clock Sources
Hardware Configuration
External Clock
ST7 OS C1 OSC 2
EX TERNAL SO URCE
Crystal/Ceramic Resonators
ST7 OSC 1 OSC2
CL 1
LOA D CAPA CITO RS
CL 2
Internal R C Oscillator
ST7 OSC1 OSC2
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6.3 RESET SEQUENCE MANAGER (RSM) 6.3.1 Introduction The reset sequence manager includes three RESET sources as shown in Figure 12: 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 11: Active Phase depending on the RESET source 4096 CPU clock cycle delay (selected by option byte) RESET vector fetch The 4096 CPU clock cycle delay allows the oscillator to stabilise and ensures that recovery has taken place from the Reset state. The shorter or longer clock cycle delay should be selected by option byte to correspond to the stabilization time of the external oscillator used in the application. Figure 12. Reset Block Diagram The RESET vector fetch phase duration is 2 clock c ycles. Figure 11. RESET Sequence Phases
RESET
Active Phase INTERNAL RESET 4096 CLOCK CYCLES FETCH VECTOR
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 Electrical Characteristic section 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 13). This detection is asynchronous and therefore the MCU can enter reset state even in HALT mode.
VDD
RO N
RESET
Filter INTERNAL RESET
PULSE GENERATOR
WATCHDOG RESET LVD RESET
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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. 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. 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) R ESET 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
Figure 13. RESET Sequences VDD
VIT+(LVD) VIT-(LVD)
LVD RESET
EXTERNAL RESET
WATCHDOG RESET
RUN
ACTIVE PHASE
RUN
ACTIVE PHASE
RUN
ACTIVE PHASE
RUN
th(RSTL)in
EXTERNAL RESET SOURCE
tw(RSTL)out
RESET PIN
WATCHDOG RESET WATCHDOG UNDERFLOW INTERNAL RESET (4096 TCPU) VECTOR FETCH
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6.4 SYSTEM INTEGRITY MANAGEMENT (SI) The System Integrity Management block contains group the Low voltage Detector (LVD) and Auxiliary Voltage Detector (AVD) functions. It is managed by the SICSR register. Note: A reset can also be triggered following the detection of an illegal opcode or prebyte code. Refer to Section 12.2.1 on page 123 for further details . 6.4.1 Low Voltage Detector (LVD) The Low Voltage Detector function (LVD) generates a static reset when the VDD supply voltage is below a VIT- reference value. This means that it secures the power-up as well as the power-down keeping the ST7 in reset. The VIT- reference value for a voltage drop is lower than the VIT+ reference value for power-on in order to avoid a parasitic reset when the MCU starts running and sinks current on the supply (hysteresis). The LVD Reset circuitry generates a reset when VDD is below: VIT+ when VDD is rising VIT- when VDD is falling The LVD function is illustrated in Figure 14. The voltage threshold can be configured by option byte to be low, medium or high. Figure 14. Low Voltage Detector vs Reset
VDD
Provided the minimum VDD value (guaranteed for the oscillator frequency) is above VIT-, the MCU can only be in two modes: under full software control in static safe reset In these conditions, secure operation is always ensured for the application without the need for external reset hardware. During a Low Voltage Detector Reset, the RESET pin is held low, thus permitting the MCU to reset other devices. Notes: The LVD allows the device to be used without any external RESET circuitry. The LVD is an optional function which can be selected by option byte. Use of LVD with capacitive power supply: with this type of power supply, if power cuts occur in the application, it is recommended to pull VDD down to 0V to ensure optimum restart conditions. Refer to circuit example in Figure 91 on page 151 and note 6. It is recommended to make sure that the VDD supply voltage rises monotonously when the device is exiting from Reset, to ensure the application functions properly.
Vhys VIT+ VIT-
RESET
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SYSTEM INTEGRITY MANAGEMENT (Cont'd) 6.4.2 Auxiliary Voltage Detector (AVD) The Voltage Detector function (AVD) is based on an analog comparison between a VIT- and VIT+ reference value and the VDD main supply. The VITreference value for falling voltage is lower than the VIT+ reference value for rising voltage in order to avoid parasitic detection (hysteresis). The output of the AVD comparator is directly readable by the application software through a real time status bit (VDF) in the SICSR register. This bit is read only. Caution: The AVD functions only if the LVD is enabled through the option byte. 6.4.2.1 Monitoring the VDD Main Supply The AVD voltage threshold value is relative to the selected LVD threshold configured by option byte (see Section 15.1 on page 162). If the AVD interrupt is enabled, an interrupt is generated when the voltage crosses the VIT+(AVD) or VIT-(AVD) threshold (AVDF bit toggles). Figure 15. Using the AVD to Monitor VDD VDD Early Warning Interrupt (Power has dropped, MCU not not yet in reset)
Vh y s t
In the case of a drop in voltage, the AVD interrupt acts as an early warning, allowing software to shut down safely before the LVD resets the microcontroller. See Figure 15. The interrupt on the rising edge is used to inform the application that the VDD warning state is over. If the voltage rise time trv is less than 256 or 4096 CPU cycles (depending on the reset delay selected by option byte), no AVD interrupt will be generated when VIT+(AVD) is reached. If trv is greater than 256 or 4096 cycles then: If the AVD interrupt is enabled before the VIT+(AVD) threshold is reached, then 2 AVD interrupts will be received: the first when the AVDIE bit is set, and the second when the threshold is reached. If the AVD interrupt is enabled after the VIT+(AVD) threshold is reached then only one AVD interrupt will occur.
VIT+(AVD) VIT-(AVD) VIT+(LVD) VIT-(LVD)
trv VOLTAGE RISE TIME
AVDF bit AVD INTERRUPT REQUES T IF AVDIE bit = 1
0
1
RESET VALUE
1
0
INTERRUPT PROCESS
INTERRUPT PROCESS
LVD RESET
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SYSTEM INTEGRITY MANAGEMENT (Cont'd) 6.4.3 Low Power Modes
Mode WAIT H ALT Description No effect on SI. AVD interrupts cause the device to exit from Wait mode. The SICSR register is frozen. Interrupt Event AVD event Enable Event Control Flag Bit AVDF A VDIE Exit from Wait Yes Exit from Halt No
set and the interrupt mask in the CC register is reset (RIM instruction).
6.4.3.1 Interrupts The AVD interrupt event generates an interrupt if the corresponding Enable Control Bit (AVDIE) is
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SYSTEM INTEGRITY MANAGEMENT (Cont'd) 6.4.4 Register Description SYSTEM INTEGRITY (SI) CONTROL/STATUS REGISTER (SICSR) Read / Write WDGRF flag description for more details. When the LVD is disabled by OPTION BYTE, the LVDRF Reset Value: 000x 000x (00h) bit value is undefined.
7 0 AVD IE A VD F LVD RF 0 0 0 0 WDG RF
Bit 3:1 = Reserved, must be kept cleared. Bit 0 = WDGRF Watchdog reset flag This bit indicates that the last Reset was generated by the Watchdog peripheral. It is set by hardware (watchdog reset) and cleared by software (writing zero) or an LVD Reset (to ensure a stable cleared state of the WDGRF flag when CPU starts). Combined with the LVDRF flag information, the flag description is given by the following table.
RESET Sources External RESET pin Watchdog LVD LV DRF 0 0 1 WDG RF 0 1 X
Bit 7 = Reserved, always read as 0. Bit 6 = AVDIE Voltage Detector interrupt enable This bit is set and cleared by software. It enables an interrupt to be generated when the AVDF flag changes (toggles). The pending interrupt information is automatically cleared when software enters the AVD interrupt routine. 0: AVD interrupt disabled 1: AVD interrupt enabled Bit 5 = AVDF Voltage Detector flag This read-only bit is set and cleared by hardware. If the AVDIE bit is set, an interrupt request is generated when the AVDF bit changes value. 0: VDD over VIT+(AVD) threshold 1: VDD under VIT-(AVD) threshold Bit 4 = LVDRF LVD reset flag This bit indicates that the last Reset was generated by the LVD block. It is set by hardware (LVD reset) and cleared by software (writing zero). See
Address (Hex.) 0025h Register Label SICSR Reset Value 7 6 AVDIE 0 5 AVDF 0
Application Notes The LVDRF flag is not cleared when another RESET type occurs (external or watchdog), the LVDRF flag remains set to keep trace of the original failure. In this case, a watchdog reset can be detected by software while an external reset can not.
4 LV DRF x
3
2
1
0 WDG R F x
0
0
0
0
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7 INTERRUPTS
7.1 INTRODUCTION The ST7 enhanced interrupt management provides the following features: Hardware interrupts Software interrupt (TRAP) Nested or concurrent interrupt management with flexible interrupt priority and level management: Up to 4 software programmable nesting levels Up to 16 interrupt vectors fixed by hardware 2 non-maskable events: RESET and TRAP This interrupt management is based on: Bit 5 and bit 3 of the CPU CC register (I1:0), Interrupt software priority registers (ISPRx), Fixed interrupt vector addresses located at the high addresses of the memory map (FFE0h to FFFFh) sorted by hardware priority order. This enhanced interrupt controller guarantees full upward compatibility with the standard (not nested) ST7 interrupt controller. 7.2 MASKING AND PROCESSING FLOW The interrupt masking is managed by the I1 and I0 bits of the CC register and the ISPRx registers which give the interrupt software priority level of each interrupt vector (see Table 4). The processing flow is shown in Figure 16 Figure 16. Interrupt Processing Flowchart
RESET PENDING INTERRUPT N Y
When an interrupt request has to be serviced: Normal processing is suspended at the end of the current instruction execution. The PC, X, A and CC registers are saved onto the stack. I1 and I0 bits of CC register are set according to the corresponding values in the ISPRx registers of the serviced interrupt vector. The PC is then loaded with the interrupt vector of the interrupt to service and the first instruction of the interrupt service routine is fetched (refer to "Interrupt Mapping" table for vector addresses). The interrupt service routine should end with the IRET instruction which causes the contents of the saved registers to be recovered from the stack. Note: As a consequence of the IRET instruction, the I1 and I0 bits will be restored from the stack and the program in the previous level will resume. Table 4. Interrupt Software Priority Levels
Interrupt software priority Level 0 (main) Level 1 Level 2 Level 3 (= interrupt disable) Level Low I1 1 0 0 1 I0 0 1 0 1
High
Interrupt has the same or a lower software priority than current one
I1:0 Interrupt has a higher software priority than current one
FETCH NEXT INSTRUCTION
THE INTERRUPT STAYS PENDING
Y
"IRET" N
RESTORE PC, X, A, CC FROM STACK
EXECUTE INSTRUCTION
STACK PC, X, A, CC LOAD I1:0 FROM INTERRUPT SW REG. LOAD PC FROM INTERRUPT VECTOR
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INTERRUPTS (Cont'd) Servicing Pending Interrupts As several interrupts can be pending at the same time, the interrupt to be taken into account is determined by the following two-step process: the highest software priority interrupt is serviced, if several interrupts have the same software priority then the interrupt with the highest hardware priority is serviced first. Figure 17 describes this decision process. Figure 17. Priority Decision Process
PENDING INTERRUPTS
3). These sources allow the processor to exit HALT mode. TRAP (Non Maskable Software Interrupt) This software interrupt is serviced when the TRAP instruction is executed. It will be serviced according to the flowchart on Figure 16 as a TLI. RESET The RESET source has the highest priority in the ST7. This means that the first current routine has the highest software priority (level 3) and the highest hardware priority. See the RESET chapter for more details. Maskable Sources Maskable interrupt vector sources can be serviced if the corresponding interrupt is enabled and if its own interrupt software priority (in ISPRx registers) is higher than the one currently being serviced (I1 and I0 in CC register). If any of these two conditions is false, the interrupt is latched and thus remains pending. External Interrupts External interrupts allow the processor to exit from HALT low power mode. External interrupt sensitivity is software selectable through the Miscellaneous registers (MISCRx). External interrupt triggered on edge will be latched and the interrupt request automatically cleared upon entering the interrupt service routine. If several input pins of a group connected to the same interrupt vector request an interrupt simultaneously, the interrupt vector will be serviced. Software can read the pin levels to identify which pin(s) are the source of the interrupt. If several input pins are selected simultaneously as interrupt source, these are logically NANDed. For this reason if one of the interrupt pins is tied low, it masks the other ones. Peripheral Interrupts Usually the peripheral interrupts cause the MCU to exit from HALT mode except those mentioned in the "Interrupt Mapping" table. A peripheral interrupt occurs when a specific flag is set in the peripheral status registers and if the corresponding enable bit is set in the peripheral control register. The general sequence for clearing an interrupt is based on an access to the status register followed by a read or write to an associated register. Note: The clearing sequence resets the internal latch. A pending interrupt (i.e. waiting for being serviced) will therefore be lost if the clear sequence is executed.
Same
SOFTWARE PRIORITY
Different
HIGHEST SOFTWARE PRIORITY SERVICED HIGHEST HARDWARE PRIORITY SERVICED
When an interrupt request is not serviced immediately, it is latched and then processed when its software priority combined with the hardware priority becomes the highest one. Note 1: The hardware priority is exclusive while the software one is not. This allows the previous process to succeed with only one interrupt. Note 2: RESET and TRAP are non-maskable and they can be considered as having the highest software priority in the decision process. Different Interrupt Vector Sources Two interrupt source types are managed by the ST7 interrupt controller: the non-maskable type (RESET and TRAP) and the maskable type (external or from internal peripherals). Non-Maskable Sources These sources are processed regardless of the state of the I1 and I0 bits of the CC register (see Figure 16). After stacking the PC, X, A and CC registers (except for RESET), the corresponding vector is loaded in the PC register and the I1 and I0 bits of the CC are set to disable interrupts (level
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INTERRUPTS (Cont'd) 7.3 INTERRUPTS AND LOW POWER MODES All interrupts allow the processor to exit the WAIT low power mode. On the contrary, only external and other specified interrupts allow the processor to exit the HALT modes (see column "Exit from HALT" in "Interrupt Mapping" table). When several pending interrupts are present while exiting HALT mode, the first one serviced can only be an interrupt with exit from HALT mode capability and it is selected through the same decision process shown in Figure 17. Note: If an interrupt, that is not able to Exit from HALT mode, is pending with the highest priority when exiting HALT mode, this interrupt is serviced after the first one serviced. 7.4 CONCURRENT & NESTED MANAGEMENT The following Figure 18 and Figure 19 show two different interrupt management modes. The first is called concurrent mode and does not allow an interrupt to be interrupted, unlike the nested mode in Figure 19. The interrupt hardware priority is given in this order from the lowest to the highest: MAIN, IT4, IT3, IT2, IT1, IT0. The software priority is given for each interrupt. Warning: A stack overflow may occur without notifying the software of the failure. Note: TLI (Top Level Interrupt) is not available in this product. Related Documentation AN1044: Multiple interrupt source management for ST7 MCUs
Figure 18. Concurrent Interrupt Management
SOFTW ARE PRIORITY LEVEL IT2 IT1 IT4 IT3 TLI IT0 I1 I0
HARDWARE PRIORITY
TLI IT0 IT1 IT2 IT3 RIM IT4 MAIN MAIN IT1
3 3 3 3 3 3 3/0 10
11 11 11 11 11 11
11 / 10 Figure 19. Nested Interrupt Management
SOFTW ARE PRIORITY LEVEL
TLI
IT2
IT1
IT4
IT3
IT0
I1
I0
HARDWARE PRIORITY
TLI IT0 IT1 IT2 IT3 RIM IT4 MAIN IT4 MAIN IT1 IT2
3 3 2 1 3 3 3/0 10
11 11 00 01 11 11
11 / 10
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USED STACK = 20 BYTES
USED STACK = 10 BY TES
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INTERRUPTS (Cont'd) 7.5 INTERRUPT REGISTER DESCRIPTION CPU CC REGISTER INTERRUPT BITS Read / Write Reset Value: 111x 1010 (xAh)
7 1 1 I1 H I0 N Z 0 C ISPR0 ISPR1 ISPR2 ISPR3
INTERRUPT SOFTWARE PRIORITY REGISTERS (ISPRX) Read/Write (bits 7:4 of ISPR3 are read only) Reset Value: 1111 1111 (FFh)
7 I1_3 I1_7 I0_3 I0_7 I1_2 I1_6 I0_2 I0_6 I1_1 I1_5 I0_1 I0_5 I0_9 I1_0 I1_4 I1_8 0 I0_0 I0_4 I0_8
Bit 5, 3 = I1, I0 Software Interrupt Priority These two bits indicate the current interrupt software priority.
Interrupt Software Priority Level 0 (main) Level 1 Level 2 Level 3 (= interrupt disable*) Level Low I1 1 0 0 1 I0 0 1 0 1
I1_11 I0_11 I1_10 I0_10 I1_9 1 1 1 1
I1_13 I0_13 I1_12 I0_12
High
These two bits are set/cleared by hardware when entering in interrupt. The loaded value is given by the corresponding bits in the interrupt software priority registers (ISPRx). They can be also set/cleared by software with the RIM, SIM, HALT, WFI, IRET and PUSH/POP instructions (see "Interrupt Dedicated Instruction Set" table). *Note: TRAP and RESET events are non maskable sources and can interrupt a level 3 program.
These four registers contain the interrupt software priority of each interrupt vector. Each interrupt vector (except RESET and TRAP) has corresponding bits in these registers where its own software priority is stored. This correspondance is shown in the following table.
Vector Address FFFBh-FFFAh FFF9h-FFF8h ... FFE1h-FFE0h ISPRx Bits ei0 ei1 ... Not used
Each I1_x and I0_x bit value in the ISPRx registers has the same meaning as the I1 and I0 bits in the CC register. Level 0 can not be written (I1_x=1, I0_x=0). In this case, the previously stored value is kept. (example: previous=CFh, write=64h, result=44h) The RESET and TRAP vectors have no software priorities. When one is serviced, the I1 and I0 bits of the CC register are both set. Caution: If the I1_x and I0_x bits are modified while the interrupt x is executed the following behaviour has to be considered: If the interrupt x is still pending (new interrupt or flag not cleared) and the new software priority is higher than the previous one, the interrupt x is re-entered. Otherwise, the software priority stays unchanged up to the next interrupt request (after the IRET of the interrupt x).
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INTERRUPTS (Cont'd) Table 5. Interrupt Mapping
N Source Block RES ET TRAP 0 1 2 3 4 5 6 7 8 9 10 11 12 13 S CI I2C S PI TIMER A MC C TIMER B AVD e i0 e i1 Reset Software Interrupt External Interrupt Port A7..0 (C5..01) External Interrupt Port B7..0 (C5..01) Not used SPI Peripheral Interrupts TIMER A Peripheral Interrupts Time base interrupt TIMER B Peripheral Interrupts Auxiliary Voltage Detector interrupt Not used Not used SCI Peripheral Interrupt I2C Peripheral Interrupt Not Used Not Used SCISR I2CSR x Lowest Priority no no SPISR T A SR MCCSR T B SR SICSR yes no yes no N/A Description Register Label Priority Order Highest Priority Exit from HALT yes no yes Address Vector FFFEh-FFFFh FFFCh-FFFDh FFFAh-FFFBh FFF8h-FFF9h FFF6h-FFF7h FFF4h-FFF5h FFF2h-FFF3h FFF0h-FFF1h FFEEh-FFEFh FFECh-FFEDh FFEAh-FFEBh FFE8h-FFE9h FFE6h-FFE7h FFE4h-FFE5h FFE2h-FFE3h FFE0h-FFE1h
Note 1. Configurable by option byte. Table 6. Nested Interrupts Register Map and Reset Values
Address (Hex.) Register Label 7 SP I 001Ch ISPR0 Reset Value I1_3 1 AVD 001Dh ISPR1 Reset Value I1_7 1 I2C 001Eh ISPR2 Reset Value I1_11 1 I0_11 1 I1_10 1 I0_7 1 I0_3 1 6 5 Not Used I1_2 1 I0_2 1 I1_1 1 M CC I1_5 1 I0_5 1 4 3 EI1 I0_1 1 I1_0 1 2 1 EI0 I0_0 1 0
TIMERB I1_6 1 S CI I0_10 1 I0_6 1
T IM ERA I1_4 1 I0_4 1
Not Used I1_9 1 I0_9 1
Not Used I1_8 1 I0_8 1
Not Used 001Fh ISPR3 Reset Value 1 1 1 1 I1_13 1 I0_13 1
Not Used I1_12 1 I0_12 1
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8 POWER SAVING MODES
8.1 INTRODUCTION To give a large measure of flexibility to the application in terms of power consumption, three main power saving modes are implemented in the ST7 (see Figure 20). After a RESET the normal operating mode is selected by default (RUN mode). This mode drives the device (CPU and embedded peripherals) by means of a master clock which is based on the main oscillator frequency divided by 2 (fCPU). From Run mode, the different power saving modes may be selected by setting the relevant register bits or by calling the specific ST7 software instruction whose action depends on the oscillator status. Figure 20. Power Saving Mode Transitions
High RUN
fCPU
8.2 SLOW MODE This mode has two targets: To reduce power consumption by decreasing the internal clock in the device, To adapt the internal clock frequency (fCPU) to the available supply voltage. SLOW mode is controlled by three bits in the MISR1 register: the SMS bit which enables or disables Slow mode and two CPx bits which select the internal slow frequency (fCPU). In this mode, the oscillator frequency can be divided by 4, 8, 16 or 32 instead of 2 in normal operating mode. The CPU and peripherals are clocked at this lower frequency. Note: SLOW-WAIT mode is activated when enterring the WAIT mode while the device is already in SLOW mode. Figure 21. SLOW Mode Clock Transitions
fOSC2/2 fOSC2/4 f OSC2
SLOW
fOSC2 MISCR1
WAIT SLOW WAIT HALT Low PO WER CONS UMPTION
CP1:0 SMS
00
01
NEW SLOW FREQUENCY REQUEST
NORMAL RUN MODE REQUEST
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POWER SAVING MODES (Cont'd) 8.3 WAIT MODE WAIT mode places the MCU in a low power consumption mode by stopping the CPU. This power saving mode is selected by calling the "WFI" ST7 software instruction. All peripherals remain active. During WAIT mode, the I [1:0] bits in the CC register are forced to `10b', to enable all interrupts. All other registers and memory remain unchanged. The MCU remains in WAIT mode until an interrupt or Reset occurs, whereupon the Program Counter branches to the starting address of the interrupt or Reset service routine. The MCU will remain in WAIT mode until a Reset or an Interrupt occurs, causing it to wake up. Refer to Figure 22. Figure 22. WAIT Mode Flowchart
OSCILLATOR PERIPHERALS CP U I[1:0] BITS ON ON OFF 0
WFI I N S T R U C T I O N
N RE SET N INTERRUP T Y OSCILLATOR PERIPHERALS CP U I[1:0] BITS ON OFF ON 1 Y
4096 CPU CLOCK CYCLE DELAY
OSCILLATOR ON PERIPHERALS ON CP U ON I[1:0] BITS X X 1)
FETC H RES ET VEC TOR OR SERVICE INTERRUPT
Note: 1. Before servicing an interrupt, the CC register is pushed on the stack. The I[1:0] bits in the CC register are set during the interrupt routine and cleared when the CC register is popped.
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8.4 ACTIVE-HALT AND HALT MODES ACTIVE-HALT and HALT modes are the two lowest power consumption modes of the MCU. They are both entered by executing the `HALT' instruction. The decision to enter either in ACTIVE-HALT or HALT mode is given by the MCC/RTC interrupt enable flag (OIE bit in MCCSR register).
MCCSR O I E bi t 0 1 Power Saving Mode entered when HALT instruction is executed HALT mode ACTIVE-HALT mode
Figure 23. ACTIVE-HALT Timing Overview
RUN ACTIVE HA LT 4096 CPU CYCLE DELAY 1) RESET OR INTER RUPT RUN
HA LT IN STRUCTION [MCCS R.OIE=1]
FE TCH VECTOR
Figure 24. ACTIVE-HALT Mode Flowchart
H A L T INSTR UCTIO N (MC C SR. O IE=1) OSCILLATOR ON PERIPHERALS 2) OFF CP U OFF 10 I[1:0] BITS N RE SET N INTERRUPT 3) Y OSCILLATOR ON PERIPHERALS OFF CP U ON I[1:0] BITS XX 4) 4096 CPU CLOCK CYCLE DELAY OSCILLATOR ON PERIPHERALS ON CP U ON I[1:0] BITS XX 4) FETC H RES ET VEC TOR OR SERVICE INTERRUPT Y
8.4.1 ACTIVE-HALT MODE ACTIVE-HALT mode is the lowest power consumption mode of the MCU with a real time clock available. It is entered by executing the `HALT' instruction when the OIE bit of the Main Clock Controller Status register (MCCSR) is set. The MCU can exit ACTIVE-HALT mode on reception of either an MCC/RTC interrupt, a specific interrupt (see Table 5, "Interrupt Mapping," on page 32) or a RESET. When exiting ACTIVE-HALT mode by means of an interrupt, no 4096 CPU cycle delay occurs. The CPU resumes operation by servicing the interrupt or by fetching the reset vector which woke it up (see Figure 24). When entering ACTIVE-HALT mode, the I[1:0] bits in the CC register are forced to `10b' to enable interrupts. Therefore, if an interrupt is pending, the MCU wakes up immediately. In ACTIVE-HALT mode, only the main oscillator and its associated counter (MCC/RTC) are running to keep a wake-up time base. All other peripherals are not clocked except those which get their clock supply from another clock generator (such as external or auxiliary oscillator). The safeguard against staying locked in ACTIVEHALT mode is provided by the oscillator interrupt. Note: As soon as the interrupt capability of one of the oscillators is selected (MCCSR.OIE bit set), entering ACTIVE-HALT mode while the Watchdog is active does not generate a RESET. This means that the device cannot spend more than a defined delay in this power saving mode.
Notes: 1. This delay occurs only if the MCU exits ACTIVEHALT mode by means of a RESET. 2. Peripheral clocked with an external clock source can still be active. 3. Only the MCC/RTC interrupt and some specific interrupts can exit the MCU from ACTIVE-HALT mode (such as external interrupt). Refer to Table 5, "Interrupt Mapping," on page 32 for more details. 4. Before servicing an interrupt, the CC register is pushed on the stack. The I[1:0] bits of the CC register are set to the current software priority level of the interrupt routine and restored when the CC register is popped.
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POWER SAVING MODES (Cont'd) 8.5 HALT MODE The HALT mode is the lowest power consumption mode of the MCU. It is entered by executing the ST7 HALT instruction (see Figure 26). The MCU can exit HALT mode on reception of either a specific interrupt (see Table 5, "Interrupt Mapping," on page 32) or a RESET. When exiting HALT mode by means of a RESET or an interrupt, the oscillator is immediately turned on and the 4096 CPU cycle delay is used to stabilize the oscillator. After the start up delay, the CPU resumes operation by servicing the interrupt or by fetching the reset vector which woke it up (see Figure 25). When entering HALT mode, the I[1:0] bits in the CC register are forced to `10b' to enable interrupts. Therefore, if an interrupt is pending, the MCU wakes immediately. In the HALT mode the main oscillator is turned off causing all internal processing to be stopped, including the operation of the on-chip peripherals. All peripherals are not clocked except the ones which get their clock supply from another clock generator (such as an external or auxiliary oscillator). The compatibility of Watchdog operation with HALT mode is configured by the "WDGHALT" option bit of the option byte. The HALT instruction when executed while the Watchdog system is enabled, can generate a Watchdog RESET (see Section 15.1 "OPTION BYTES" on page 162 for more details). Figure 25. HALT Mode Timing Overview
RUN HALT 4096 CPU CYCLE D EL AY RUN FETC H RES ET VEC TOR OR SERVICE INTERRUPT
Figure 26. HALT Mode Flowchart
H AL T INSTRUCTION ENABLE W D GH A L T 1 ) 1 W ATCHDO G RE SET OSCILLATOR OFF PERIPHERALS 2) OFF CP U OFF I[1:0] BITS 0 0 W ATCHDOG DISABLE
N RE SET N Y INTERRUPT 3) Y OSCILLATOR PERIPHERALS CP U I[1:0] BITS ON OFF ON 1
4096 CPU CLOCK CYCLE DELAY OSCILLATOR ON PERIPHERALS ON CP U ON I[1:0] BITS XX 4)
HA LT IN STRUCTION
RESET OR INTER RUPT
FE TCH VECTOR
Notes: 1. WDGHALT is an option bit. See option byte section for more details. 2. Peripheral clocked with an external clock source can still be active. 3. Only some specific interrupts can exit the MCU from HALT mode (such as external interrupt). Refer to Table 5, "Interrupt Mapping," on page 32 for more details. 4. Before servicing an interrupt, the CC register is pushed on the stack. The I[1:0] bits in the CC register are set during the interrupt routine and cleared when the CC register is popped.
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POWER SAVING MODES (Cont'd) 8.5.0.1 Halt Mode Recommendations Make sure that an external event is available to wake up the microcontroller from Halt mode. When using an external interrupt to wake up the microcontroller, reinitialize the corresponding I/O as "Input Pull-up with Interrupt" before executing the HALT instruction. The main reason for this is that the I/O may be wrongly configured due to external interference or by an unforeseen logical condition. For the same reason, reinitialize the level sensitiveness of each external interrupt as a precautionary measure. The opcode for the HALT instruction is 0x8E. To avoid an unexpected HALT instruction due to a program counter failure, it is advised to clear all occurrences of the data value 0x8E from memory. For example, avoid defining a constant in ROM with the value 0x8E. As the HALT instruction clears the interrupt mask in the CC register to allow interrupts, the user may choose to clear all pending interrupt bits before executing the HALT instruction. This avoids entering other peripheral interrupt routines after executing the external interrupt routine corresponding to the wake-up event (reset or external interrupt). Related Documentation AN 980: ST7 Keypad Decoding Techniques, Implementing Wake-Up on Keystroke AN1014: How to Minimize the ST7 Power Consumption AN1605: Using an active RC to wakeup the ST7LITE0 from power saving mode
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9 I/O PORTS
9.1 INTRODUCTION The I/O ports allow data transfer. An I/O port can contain up to 8 pins. Each pin can be programmed independently either as a digital input or digital output. In addition, specific pins may have several other functions. These functions can include external interrupt, alternate signal input/output for onchip peripherals or analog input. 9.2 FUNCTIONAL DESCRIPTION A Data Register (DR) and a Data Direction Register (DDR) are always associated with each port. The Option Register (OR), which allows input/output options, may or may not be implemented. The following description takes into account the OR register. Refer to the Port Configuration table for device specific information. An I/O pin is programmed using the corresponding bits in the DDR, DR and OR registers: bit x corresponding to pin x of the port. Figure 27 shows the generic I/O block diagram. 9.2.1 Input Modes Clearing the DDRx bit selects input mode. In this mode, reading its DR bit returns the digital value from that I/O pin. If an OR bit is available, different input modes can be configured by software: floating or pull-up. Refer to I/O Port Implementation section for configuration. Notes: 1. Writing to the DR modifies the latch value but does not change the state of the input pin. 2. Do not use read/modify/write instructions (BSET/BRES) to modify the DR register. External Interrupt Function Depending on the device, setting the ORx bit while in input mode can configure an I/O as an input with interrupt. In this configuration, a signal edge or level input on the I/O generates an interrupt request via the corresponding interrupt vector (eix). Falling or rising edge sensitivity is programmed independently for each interrupt vector. The External Interrupt Control Register (EICR) or the Miscellaneous Register controls this sensitivity, depending on the device. A device may have up to 7 external interrupts. Several pins may be tied to one external interrupt vector. Refer to Pin Description to see which ports have external interrupts. If several I/O interrupt pins on the same interrupt vector are selected simultaneously, they are logically combined. For this reason if one of the interrupt pins is tied low, it may mask the others. External interrupts are hardware interrupts. Fetching the corresponding interrupt vector automatically clears the request latch. Modifying the sensitivity bits will clear any pending interrupts. 9.2.2 Output Modes Setting the DDRx bit selects output mode. Writing to the DR bits applies a digital value to the I/O through the latch. Reading the DR bits returns the previously stored value. If an OR bit is available, different output modes can be selected by software: push-pull or opendrain. Refer to I/O Port Implementation section for configuration. DR Value and Output Pin Status
DR 0 1 Push-Pull VOL V OH Op e n - D r a i n VOL Floating
9.2.3 Alternate Functions Many ST7s I/Os have one or more alternate functions. These may include output signals from, or input signals to, on-chip peripherals. The Device Pin Description table describes which peripheral signals can be input/output to which ports. A signal coming from an on-chip peripheral can be output on an I/O. To do this, enable the on-chip peripheral as an output (enable bit in the peripheral's control register). The peripheral configures the I/O as an output and takes priority over standard I/ O programming. The I/O's state is readable by addressing the corresponding I/O data register. Configuring an I/O as floating enables alternate function input. It is not recommended to configure an I/O as pull-up as this will increase current consumption. Before using an I/O as an alternate input, configure it without interrupt. Otherwise spurious interrupts can occur. Configure an I/O as input floating for an on-chip peripheral signal which can be input and output. Caution: I/Os which can be configured as both an analog and digital alternate function need special attention. The user must control the peripherals so that the signals do not arrive at the same time on the same pin. If an external clock is used, only the clock alternate function should be employed on that I/O pin and not the other alternate function.
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I/O PORTS (Cont'd) Figure 27. I/O Port General Block Diagram
REGISTER ACCESS ALTERNATE O UT PUT
From on-chip peripheral
1 0
VDD
P-BUFFER (see table below) PULL-UP (see table below) VDD
ALTERNATE EN ABLE BIT DR
DDR
PULL-UP CON DITION
DATA BUS
PA D
OR OR SEL
If implemented
N-BUFFER DDR SEL CMOS SCHMITT TRIG GER
DIO D ES (see table below) ANALO G INPUT
DR SEL
1 0
ALTERNATE INPUT
Combinational Logic To on-chip peripheral
EXTERNAL INTERR UPT REQUEST (eix)
SENSITIVITY SELECTION
FRO M O T HER BITS Note: Refer to the Port Configuration
table for device specific information.
Table 7. I/O Port Mode Options
Configuration Mode Input Floating with/without Interrupt Pull-up with/without Interrupt Push-pull Open Drain (logic level) True Open Drain Pull-Up Off On Off NI P-Buffer Off On Off NI On On Diodes to VDD t o VS S
O u tput
NI (see note)
Legend:NI - not implemented Off - implemented not activated On - implemented and activated
Note: The diode to VDD is not implemented in the true open drain pads. A local protection between the pad and VOL is implemented to protect the device against positive stress.
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I/O PORTS (Cont'd) Table 8. I/O Configurations
Hardware Configuration
VDD RPU PAD NOTE 3 PULL-UP CONDITION DR REGISTER ACCESS
DR REGISTER
W DATA BUS R
INPUT 1)
FROM OTHER PINS INTERRUPT COMBINATIONAL POLARITY LOGIC SELECTION CONDITION
ALTERNATE INPUT To on-chip peripheral EXTERNAL INTERRUPT SOURCE (eix)
ANALOG INPUT
OPEN-DRAIN O UTPUT 2 )
VDD RPU PAD
NOTE 3 DR REGISTER ACCESS
DR REGISTER
R/W
DATA BUS
P U S H - P U L L OU T P U T 2 )
VDD RPU PAD
NOTE 3
DR REGISTER ACCESS
DR REGISTER
R/W
DATA BUS
ALTERNATE ENABLE BIT
ALTERNATE OUTPUT From on-chip peripheral
Notes: 1. When the I/O port is in input configuration and the associated alternate function is enabled as an output, reading the DR register will read the alternate function output status. 2. When the I/O port is in output configuration and the associated alternate function is enabled as an input, the alternate function reads the pin status given by the DR register content. 3. For true open drain, these elements are not implemented.
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I/O PORTS (Cont'd) Analog alternate function Configure the I/O as floating input to use an ADC input. The analog multiplexer (controlled by the ADC registers) switches the analog voltage present on the selected pin to the common analog rail, connected to the ADC input. Analog Recommendations Do not change the voltage level or loading on any I/O while conversion is in progress. Do not have clocking pins located close to a selected analog pin. WARNING: The analog input voltage level must be within the limits stated in the absolute maximum ratings. 9.3 I/O PORT IMPLEMENTATION The hardware implementation on each I/O port depends on the settings in the DDR and OR registers and specific I/O port features such as ADC input or open drain. Switching these I/O ports from one state to another should be done in a sequence that prevents unwanted side effects. Recommended safe transitions are illustrated in Figure 28. Other transitions are potentially risky and should be avoided, since they may present unwanted side-effects such as spurious interrupt generation. Figure 28. Interrupt I/O Port State Transitions
01
INPUT floating/pull-up interrupt
9.4 UNUSED I/O PINS Unused I/O pins must be connected to fixed voltage levels. Refer to Section 13.8. 9.5 LOW POWER MODES
Mode WAIT H AL T Description No effect on I/O ports. External interrupts cause the device to exit from WAIT mode. No effect on I/O ports. External interrupts cause the device to exit from HALT mode.
9.6 INTERRUPTS The external interrupt event generates an interrupt if the corresponding configuration is selected with DDR and OR registers and if the I bit in the CC register is cleared (RIM instruction).
Interrupt Event External interrupt on selected external event Enable Event Control Flag Bit DDRx OR x Exit from Wait Yes Exit from Halt Yes
00
INPUT floating (reset state)
10
OUTPUT open-drain
11
OUTPUT push-pull
Related Documentation AN 970: SPI Communication between ST7 and E EPROM AN1045: S/W implementation of I2C bus master AN1048: Software LCD driver
XX
= DDR, OR
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I/O PORTS (Cont'd) 9.7 DEVICE-SPECIFIC I/O PORT CONFIGURATION The I/O port register configurations are summarised as follows. Interrupt Ports PA7, PA5, PA3:0, PB7:0, PC5:0 (with pull-up)
MODE floating input pull-up interrupt input open drain output push-pull output D DR 0 0 1 1 OR 0 1 0 1
True Open Drain Interrupt Ports PA6, PA4 (without pull-up)
MODE floating input floating interrupt input open drain (high sink ports) D DR 0 0 1 OR 0 1 X
Table 9. Port Configuration
Input (DDR = 0) Port Pin Name OR = 0 PA7 PA6 PA5 PA4 PA3:0 PB7:0 PC5:0 floating floating floating floating floating floating floating OR = 1 pull-up interrupt floating interrupt pull-up interrupt floating interrupt pull-up interrupt pull-up interrupt pull-up interrupt OR = 0 OR = 1 High-Sink open drain push-pull true open-drain open drain push-pull true open-drain open drain push-pull open drain push-pull open drain push-pull Output (DDR = 1)
Port A
Y es
Port B Port C
No
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I/O PORTS (Cont'd) 9.8 I/O PORT REGISTER DESCRIPTION DATA REGISTER (DR) Port x Data Register PxDR with x = A, B or C. Read / Write Reset Value: 0000 0000 (00h)
7 D7 D6 D5 D4 D3 D2 D1 0 D0
OPTION REGISTER (OR) Port x Option Register PxOR with x = A, B or C. Read / Write Reset Value: 0000 0000 (00h)
7 O7 O6 O5 O4 O3 O2 O1 0 O0
Bits 7:0 = D[7:0] Data register 8 bits. The DR register has a specific behaviour according to the selected input/output configuration. Writing the DR register is always taken into account even if the pin is configured as an input; this allows always having the expected level on the pin when toggling to output mode. Reading the DR register returns either the DR register latch content (pin configured as output) or the digital value applied to the I/O pin (pin configured as input). DATA DIRECTION REGISTER (DDR) Port x Data Direction Register PxDDR with x = A, B or C. Read / Write Reset Value: 0000 0000 (00h)
7 DD7 DD6 DD5 DD4 DD3 DD2 DD1 0 DD0
Bits 7:0 = O[7:0] Option register 8 bits. For specific I/O pins, this register is not implemented. In this case the DDR register is enough to select the I/O pin configuration. The OR register allows to distinguish: in input mode if the pull-up with interrupt capability or the basic pull-up configuration is selected, in output mode if the push-pull or open drain configuration is selected. Each bit is set and cleared by software. Input mode: 0: Floating input 1: Pull-up input with or without interrupt Output mode: 0: Output open drain (with P-Buffer unactivated) 1: Output push-pull (when available)
Bits 7:0 = DD[7:0] Data direction register 8 bits. The DDR register gives the input/output direction configuration of the pins. Each bit is set and cleared by software. 0: Input mode 1: Output mode
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I/O PORTS (Cont'd) Table 10. I/O Port Register Map and Reset Values
Address (Hex.) Register Label 7 6 5 4 3 2 1 0
Reset Value of all I/O port registers 0000h 0001h 0002h 0004h 0005h 0006h 0008h 0009h 000Ah P CDR P CDDR P C OR P BDR P BDDR P B OR P ADR P ADDR P A OR
0
0
0
0
0
0
0
0
MSB
LSB
MSB
LSB
MSB
LSB
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10 MISCELLANEOUS REGISTERS
The miscellaneous registers allow control over several different features such as the external interrupts or the I/O alternate functions. 10.1 I/O PORT INTERRUPT SENSITIVITY The external interrupt sensitivity is controlled by the ISxx bits of the Miscellaneous register and the OPTION BYTE. This control allows you to have two fully independent external interrupt source sensitivities with configurable sources (using the EXTIT option bit) as shown in Figure 29 and Figure 30. Each external interrupt source can be generated on four different events on the pin: Falling edge Rising edge Falling and rising edge Falling edge and low level To guarantee correct functionality, the sensitivity bits in the MISCR1 register must be modified only when the I[1:0] bits in the CC register are set to 1 (interrupt masked). See Section 9.8 "I/O PORT REGISTER DESCRIPTION" on page 43 and Section 10.3 "MISCELLANEOUS REGISTER DESCRIPTION" on page 46 for more details on the programming.
PA0 PC5
Figure 29. Ext. Interrupt Sensitivity (EXTIT=0)
MISCR1 ei0 INTERRUPT SOURCE IS00 IS01
PA7
SENSITIVITY CONTROL
PC0 MISCR1 ei1 INTERRUPT SOURCE IS10 IS11
PB7
SENSITIVITY CONTROL
PB0
Figure 30. Ext. Interrupt Sensitivity (EXTIT=1)
MISCR1 ei0 INTERRUPT SOURCE IS00 IS01
PA7
SENSITIVITY CONTROL
PA0
10.2 I/O PORT ALTERNATE FUNCTIONS The MISCR registers manage four I/O port miscellaneous alternate functions: Main clock signal (fCPU) output on PC2 SPI pin configuration: SS pin internal control to use the PB7 I/O port function while the SPI is active. Master output capability on the MOSI pin (PB4) deactivated while the SPI is active. Slave output capability on the MISO pin (PB5) deactivated while the SPI is active. These functions are described in detail in the Section 10.3 "MISCELLANEOUS REGISTER DESCRIPTION" on page 46.
PB7 ei1 INTERRUPT SOURCE
MISCR1 IS10 IS11
PB0 PC5
SENSITIVITY CONTROL
PC0
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MISCELLANEOUS REGISTERS (Cont'd) 10.3 MISCELLANEOUS REGISTER DESCRIPTION MISCELLANEOUS REGISTER 1 (MISCR1) Read / Write Reset Value: 0000 0000 (00h)
7 IS11 IS10 MC O I S01 I S00 CP1 CP0 0 fCPU in SLOW mode SMS fOSC2 / 2 fOSC2 / 4 fOSC2 / 8 CP1 0 1 0 1 CP0 0 0 1 1
Bits 2:1 = CP[1:0] CPU clock prescaler These bits select the CPU clock prescaler which is applied in the various slow modes. Their action is conditioned by the setting of the SMS bit. These two bits are set and cleared by software
Bits 7:6 = IS1[1:0] ei1 sensitivity The interrupt sensitivity, defined using the IS1[1:0] bits, is applied to the ei1 external interrupts. These two bits can be written only when the I[1:0] bits in the CC register are set to 1 (interrupt masked). ei1: Port B (C optional)
External Interrupt Sensitivity Falling edge & low level Rising edge only Falling edge only Rising and falling edge I S11 I S10 0 0 1 1 0 1 0 1
fOSC2 / 16
Bit 0 = SMS Slow mode select This bit is set and cleared by software. 0: Normal mode. fCPU = fOSC2 1: Slow mode. fCPU is given by CP1, CP0 See low power consumption mode and MCC chapters for more details.
Bit 5 = MCO Main clock out selection This bit enables the MCO alternate function on the PC2 I/O port. It is set and cleared by software. 0: MCO alternate function disabled (I/O pin free for general-purpose I/O) 1: MCO alternate function enabled (fCPU on I/O port) Bits 4:3 = IS0[1:0] ei0 sensitivity The interrupt sensitivity, defined using the IS0[1:0] bits, is applied to the ei0 external interrupts. These two bits can be written only when the I[1:0] bits inthe CC register are set to 1 (interrupt masked). ei0: Port A (C optional)
External Interrupt Sensitivity Falling edge & low level Rising edge only Falling edge only Rising and falling edge IS01 IS00 0 0 1 1 0 1 0 1
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MISCELLANEOUS REGISTERS (Cont'd) MISCELLANEOUS REGISTER 2 (MISCR2) Read / Write Reset Value: 0000 0000 (00h)
7 0 0 0 0 M OD S O D S S M 0 SSI
Caution: This register has been provided for compatibility with the ST72254 family only. The same bits are available in the SPICSR register. New applications must use the SPICSR register. Do not use both registers, this will cause the SPI to malfunction. Bits 7:4 = Reserved always read as 0 Bits 3 = MOD SPI Master Output Disable This bit is set and cleared by software. When set, it disables the SPI Master (MOSI) output signal. 0: SPI Master Output enabled. 1: SPI Master Output disabled. Bit 2 = SOD SPI Slave Output Disable This bit is set and cleared by software. When set it disable the SPI Slave (MISO) output signal. 0: SPI Slave Output enabled. 1: SPI Slave Output disabled. Bit 1 = SSM SS mode selection This bit is set and cleared by software. 0: Normal mode - the level of the SPI SS signal is input from the external SS pin. 1: I/O mode, the level of the SPI SS signal is read from the SSI bit. Bit 0 = SSI SS internal mode This bit replaces the SS pin of the SPI when the SSM bit is set to 1. (see SPI description). It is set and cleared by software.
Table 11. Miscellaneous Register Map and Reset Values
Address (Hex.) 0020h 0040h Register Label MISCR1 Reset Value MISCR2 Reset Value 7 IS11 0 0 6 IS10 0 0 5 MCO 0 0 4 IS01 0 0 3 IS00 0 MOD 0 2 CP 1 0 SO D 0 1 CP0 0 S SM 0 0 SMS 0 SS I 0
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11 ON-CHIP PERIPHERALS
11.1 WATCHDOG TIMER (WDG) 11.1.1 Introduction The Watchdog timer is used to detect the occurrence of a software fault, usually generated by external interference or by unforeseen logical conditions, which causes the application program to abandon its normal sequence. The Watchdog circuit generates an MCU reset on expiry of a programmed time period, unless the program refreshes the counter's contents before the T6 bit becomes cleared. 11.1.2 Main Features Programmable free-running downcounter Programmable reset Reset (if watchdog activated) when the T6 bit reaches zero Optional reset on HALT instruction (configurable by option byte) Hardware Watchdog selectable by option byte 11.1.3 Functional Description The counter value stored in the Watchdog Control register (WDGCR bits T[6:0]), is decremented every 16384 fOSC2 cycles (approx.), and the length of the timeout period can be programmed by the user in 64 increments. If the watchdog is activated (the WDGA bit is set) and when the 7-bit timer (bits T[6:0]) rolls over from 40h to 3Fh (T6 becomes cleared), it initiates a reset cycle pulling low the reset pin for typically 500ns. The application program must write in the WDGCR register at regular intervals during normal operation to prevent an MCU reset. This downcounter is free-running: it counts down even if the watchdog is disabled. The value to be stored in the WDGCR register must be between FFh and C0h: The WDGA bit is set (watchdog enabled) The T6 bit is set to prevent generating an immediate reset The T[5:0] bits contain the number of increments which represents the time delay before the watchdog produces a reset (see Figure 32. Approximate Timeout Duration). The timing varies between a minimum and a maximum value due to the unknown status of the prescaler when writing to the WDGCR register (see Figure 33). Following a reset, the watchdog is disabled. Once activated it cannot be disabled, except by a reset. The T6 bit can be used to generate a software reset (the WDGA bit is set and the T6 bit is cleared). If the watchdog is activated, the HALT instruction will generate a Reset.
Figure 31. Watchdog Block Diagram
RESE T
fOSC2 MCC/RTC
WATCHDOG CONTROL REGISTER (WDGCR) DIV 64 WDG A T6 T5 T4 T3 T2 T1 T0
6-BIT DOWNCOUNTER (CNT)
12-BIT MCC RTC COUNTER M SB
11 65
LSB
0
TB[1:0] bits (M CCSR Register)
WDG PRESCALER DIV 4
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WATCHDOG TIMER (Cont'd) 11.1.4 How to Program the Watchdog Timeout Figure 32 shows the linear relationship between the 6-bit value to be loaded in the Watchdog Counter (CNT) and the resulting timeout duration in milliseconds. This can be used for a quick calculation without taking the timing variations into account. If Figure 32. Approximate Timeout Duration 3F 38 30
more precision is needed, use the formulae in Figure 33. Caution: When writing to the WDGCR register, always write 1 in the T6 bit to avoid generating an immediate reset.
CNT Value (hex.)
28 20 18
10 08 00 1.5 18 34 50 65 82 98 114 128 Watchdog timeout (ms) @ 8 MHz. fOSC2
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WATCHDOG TIMER (Cont'd) Figure 33. Exact Timeout Duration (tmin and tmax) W HE RE : tmin0 = (LSB + 128) x 64 x tOSC2 tmax0 = 16384 x tOSC2 tOSC2 = 125ns if fOSC2=8 MHz CNT = Value of T[5:0] bits in the WDGCR register (6 bits) MSB and LSB are values from the table below depending on the timebase selected by the TB[1:0] bits in the MCCSR register
TB1 Bit TB0 Bit (MCCSR Reg.) (MCCSR Reg.) 0 0 0 1 1 0 1 1 Selected MCCSR Timebase 2ms 4ms 10ms 25ms MSB 4 8 20 49 L SB 59 53 35 54
To calculate the minimum Watchdog Timeout (tmin):
S IF C N T < M------B ---- --4
T H E N t m i n = t m i n 0 + 16384 × C N T × t o s c 2
NT NT ELSE t m i n = t m i n 0 + 16384 × C N T 4--C--------- + ( 192 + L S B ) × 64 × 4--C---------- ---- -- MSB MSB
× to s c 2
To calculate the maximum Watchdog Timeout (tmax):
S IF C N T M------B ---- --4
THEN t m a x = t m a x 0 + 16384 × C N T × t o s c 2
NT NT ELSE t m a x = t m a x 0 + 16384 × C N T 4--C--------- + ( 192 + L S B ) × 64 × 4--C---------- ---- -- MSB MSB
× to s c 2
Note: In the above formulae, division results must be rounded down to the next integer value. Example: With 2ms timeout selected in MCCSR register
Value of T[5:0] Bits in WDGCR Register (Hex.) 00 3F Min. Watchdog Timeout (ms) tmin 1.496 128 Max. Watchdog Timeout (ms) tmax 2.048 128.552
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WATCHDOG TIMER (Cont'd) 11.1.5 Low Power Modes Mode SLOW WAIT Description No effect on Watchdog. No effect on Watchdog.
OIE bit in MCCSR register WDGHALT bit in Option Byte No Watchdog reset is generated. The MCU enters Halt mode. The Watchdog counter is decremented once and then stops counting and is no longer able to generate a watchdog reset until the MCU receives an external interrupt or a reset. If an external interrupt is received, the Watchdog restarts counting after 256 or 4096 CPU clocks. If a reset is generated, the Watchdog is disabled (reset state) unless Hardware Watchdog is selected by option byte. For application recommendations see Section 11.1.7 below. A reset is generated. No reset is generated. The MCU enters Active Halt mode. The Watchdog counter is not decremented. It stop counting. When the MCU receives an oscillator interrupt or external interrupt, the Watchdog restarts counting immediately. When the MCU receives a reset the Watchdog restarts counting after 256 or 4096 CPU clocks.
0
0
HALT
0
1
1
x
11.1.6 Hardware Watchdog Option If Hardware Watchdog is selected by option byte, the watchdog is always active and the WDGA bit in the WDGCR is not used. Refer to the Option Byte d e s c r i p t io n . 11.1.7 Using Halt Mode with the WDG (WDGHALT option) The following recommendation applies if Halt mode is used when the watchdog is enabled. Before executing the HALT instruction, refresh the WDG counter, to avoid an unexpected WDG reset immediately after waking up the microcontroller. 11.1.8 Interrupts None.
11.1.9 Register Description CONTROL REGISTER (WDGCR) Read / Write Reset Value: 0111 1111 (7Fh)
7 WDG A T6 T5 T4 T3 T2 T1 0 T0
Bit 7 = WDGA Activation bit. This bit is set by software and only cleared by hardware after a reset. When WDGA = 1, the watchdog can generate a reset. 0: Watchdog disabled 1: Watchdog enabled Note: This bit is not used if the hardware watchdog option is enabled by option byte. Bit 6:0 = T[6:0] 7-bit counter (MSB to LSB). These bits contain the value of the watchdog counter. It is decremented every 16384 fOSC2 cycles (approx.). A reset is produced when it rolls over from 40h to 3Fh (T6 becomes cleared).
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Table 12. Watchdog Timer Register Map and Reset Values
Address (Hex.) 0024h Register Label W D GC R Reset Value 7 W D GA 0 6 T6 1 5 T5 1 4 T4 1 3 T3 1 2 T2 1 1 T1 1 0 T0 1
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11.2 MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK (MCC/RTC) The Main Clock Controller consists of a real time clock timer with interrupt capability 11.2.1 Real Time Clock Timer (RTC) The counter of the real time clock timer allows an interrupt to be generated based on an accurate real time clock. Four different time bases depending directly on fOSC2 are available. The whole functionality is controlled by four bits of the MCCSR register: TB[1:0], OIE and OIF. When the RTC interrupt is enabled (OIE bit set), the ST7 enters ACTIVE-HALT mode when the HALT instruction is executed. See Section 8.4 "ACTIVE-HALT AND HALT MODES" on page 35 for more details.
Figure 34. Main Clock Controller (MCC/RTC) Block Diagram
fOSC2 RTC COUNTER TO WATCHDOG
TB1 T B0 OIE MCCSR
OIF MCC/RTC INTERRUPT
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MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK (Cont'd) 11.2.2 Low Power Modes Bit 3:2 = TB[1:0] Time base control
Mode WAIT Description No effect on MCC/RTC peripheral. MCC/RTC interrupt cause the device to exit from WAIT mode. No effect on MCC/RTC counter (OIE bit is set), the registers are frozen. MCC/RTC interrupt cause the device to exit from ACTIVE-HALT mode. MCC/RTC counter and registers are frozen. MCC/RTC operation resumes when the MCU is woken up by an interrupt with "exit from HALT" capability.
These bits select the programmable divider time base. They are set and cleared by software.
Time Base Counter Prescaler f OSC2 =4MHz fOSC2=8MHz 16000 32000 80000 20 0 0 4ms 8ms 20ms 50ms 2ms 4ms 10m s 25m s TB1 0 0 1 1 TB0 0 1 0 1
A C TIVEH AL T
H AL T
11.2.3 Interrupts The MCC/RTC interrupt event generates an interrupt if the OIE bit of the MCCSR register is set and the interrupt mask in the CC register is not active (RIM instruction).
Interrupt Event Time base overflow event Enable Event Control Flag Bit OIF OIE Exit from Wait Ye s Exit from Halt No 1 )
A modification of the time base is taken into account at the end of the current period (previously set) to avoid an unwanted time shift. This allows to use this time base as a real time clock. Bit 1 = OIE Oscillator interrupt enable This bit set and cleared by software. 0: Oscillator interrupt disabled 1: Oscillator interrupt enabled This interrupt can be used to exit from ACTIVEHALT mode. When this bit is set, calling the ST7 software HALT instruction enters the ACTIVE-HALT power saving mode. Bit 0 = OIF Oscillator interrupt flag This bit is set by hardware and cleared by software reading the CSR register. It indicates when set that the main oscillator has reached the selected elapsed time (TB1:0). 0: Timeout not reached 1: Timeout reached CAUTION: The BRES and BSET instructions must not be used on the MCCSR register to avoid unintentionally clearing the OIF bit.
Note: The MCC/RTC interrupt wakes up the MCU from ACTIVE-HALT mode, not from HALT mode. 11.2.4 Register Description MCC CONTROL/STATUS REGISTER (MCCSR) Read / Write Reset Value: 0000 0000 (00h)
7 0 0 0 0 T B1 T B0 OIE 0 OIF
Bit 7:4 = reserved Table 13. Main Clock Controller Register Map and Reset Values
Address (Hex.) 0025h 0026h Register Label SICSR Reset Value M CCSR Reset Value 7 6 AVDIE 0 0 5 AVDF 0 0 4 LV DRF x 0 3 2 1 0 WDG R F x OIF 0
0 0
0 TB1 0
0 TB0 0
0 OIE 0
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11.3 16-BIT TIMER 11.3.1 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 devices of the ST7 family have two on-chip 16-bit timers. They are completely in |
