- 您现在的位置：买卖IC网 > PDF目录69366 > ST72C254G1B7 (STMICROELECTRONICS) 8-BIT, FLASH, 6 MHz, MICROCONTROLLER, PDIP32 PDF资料下载
参数资料
| 型号： | ST72C254G1B7 |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 微控制器/微处理器 |
| 英文描述： | 8-BIT, FLASH, 6 MHz, MICROCONTROLLER, PDIP32 |
| 封装： | SHRINK, PLASTIC, DIP-32 |
| 文件页数： | 69/136页 |
| 文件大小： | 929K |
| 代理商： | ST72C254G1B7 |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页第37页第38页第39页第40页第41页第42页第43页第44页第45页第46页第47页第48页第49页第50页第51页第52页第53页第54页第55页第56页第57页第58页第59页第60页第61页第62页第63页第64页第65页第66页第67页第68页当前第69页第70页第71页第72页第73页第74页第75页第76页第77页第78页第79页第80页第81页第82页第83页第84页第85页第86页第87页第88页第89页第90页第91页第92页第93页第94页第95页第96页第97页第98页第99页第100页第101页第102页第103页第104页第105页第106页第107页第108页第109页第110页第111页第112页第113页第114页第115页第116页第117页第118页第119页第120页第121页第122页第123页第124页第125页第126页第127页第128页第129页第130页第131页第132页第133页第134页第135页第136页
ST72104G, ST72215G, ST72216G, ST72254G
38/136
WATCHDOG TIMER (Cont’d)
Table 11. Watchdog Timing (fCPU = 8 MHz)
Notes: Following a reset, the watchdog is disa-
bled. Once activated it cannot be disabled, except
by a reset.
The T6 bit can be used to generate a software re-
set (the WDGA bit is set and the T6 bit is cleared).
12.1.4 Hardware Watchdog Option
If Hardware Watchdog is selected by option byte,
the watchdog is always active and the WDGA bit in
the CR is not used.
Refer to the device-specific Option Byte descrip-
tion.
12.1.5 Low Power Modes
WAIT Instruction
No effect on Watchdog.
HALT Instruction
If the Watchdog reset on HALT option is selected
by option byte, a HALT instruction causes an im-
mediate reset generation if the Watchdog is acti-
vated (WDGA bit is set).
12.1.5.1 Using Halt Mode with the WDG (option)
If the Watchdog reset on HALT option is not se-
lected by option byte, the Halt mode can be used
when the watchdog is enabled.
In this case, the HALT instruction stops the oscilla-
tor. When the oscillator is stopped, the WDG stops
counting and is no longer able to generate a reset
until the microcontroller receives an external inter-
rupt or a reset.
If an external interrupt is received, the WDG re-
starts counting after 4096 CPU clocks. If a reset is
generated, the WDG is disabled (reset state).
Recommendations
– Make sure that an external event is available to
wake up the microcontroller from Halt mode.
– Before executing the HALT instruction, refresh
the WDG counter, to avoid an unexpected WDG
reset immediately after waking up the microcon-
troller.
– 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 ex-
ternal interference or by an unforeseen logical
condition.
– For the same reason, reinitialize the level sensi-
tiveness of each external interrupt as a precau-
tionary measure.
– The opcode for the HALT instruction is 0x8E. To
avoid an unexpected HALT instruction due to a
program counter failure, it is advised to clear all
occurrences of the data value 0x8E from memo-
ry. For example, avoid defining a constant in
ROM with the value 0x8E.
– As the HALT instruction clears the I bit in the CC
register to allow interrupts, the user may choose
to clear all pending interrupt bits before execut-
ing 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).
12.1.6 Interrupts
None.
12.1.7 Register Description
CONTROL REGISTER (CR)
Read/Write
Reset Value: 0111 1111 (7Fh)
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
Bit 6:0 = T[6:0]
7-bit timer (MSB to LSB).
These bits contain the decremented value. A reset
is produced when it rolls over from 40h to 3Fh (T6
becomes cleared).
CR Register
initial value
WDG timeout period
(ms)
Max
FFh
98.304
Min
C0h
1.536
70
WDGA
T6
T5
T4
T3
T2
T1
T0
相关PDF资料 |
PDF描述 |
|---|---|
| ST72C334J2TC | 8-BIT, FLASH, 8 MHz, MICROCONTROLLER, PQFP44 |
| ST72314N2TB/XXX | 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PQFP64 |
| ST72C314N4TC | 8-BIT, FLASH, 8 MHz, MICROCONTROLLER, PQFP64 |
| ST72124J2TC/XXX | 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PQFP44 |
| ST72334J4TB/XXX | 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PQFP44 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ST72C254G1M6 | 功能描述:8位微控制器 -MCU Flash 4K SPI/I2C RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT |
| ST72C254G2B1 | 制造商:STMicroelectronics 功能描述:8-BIT MICROCONTROLLER - Bulk |
| ST72C254G2B6 | 功能描述:8位微控制器 -MCU Flash 8K SPI/I2C RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT |
| ST72C254G2B6 | 制造商:STMicroelectronics 功能描述:8BIT MCU FLASH 8K 72C254 DIP32 |
| ST72C254G2M3 | 功能描述:8位微控制器 -MCU ST72104G ST72215G ST72254G 8B MCU RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT |
发布紧急采购，3分钟左右您将得到回复。