參數(shù)資料
型號: ST7260E2M1/XXX
廠商: STMICROELECTRONICS
元件分類: 微控制器/微處理器
英文描述: 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDSO24
封裝: 0.300 INCH, LEAD FREE, PLASTIC, SOP-24
文件頁數(shù): 49/118頁
文件大?。?/td> 2304K
代理商: ST7260E2M1/XXX
ST7260
36/117
11 ON-CHIP PERIPHERALS
11.1 WATCHDOG TIMER (WDG)
11.1.1 Introduction
The Watchdog timer is used to detect the occur-
rence of a software fault, usually generated by ex-
ternal interference or by unforeseen logical condi-
tions, which causes the application program to
abandon its normal sequence. The Watchdog cir-
cuit generates an MCU reset on expiry of a pro-
grammed time period, unless the program refresh-
es the counter’s contents before the T6 bit be-
comes cleared.
11.1.2 Main Features
Programmable
free-running
counter
(64
increments of 49,152 CPU cycles)
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 CR register (bits
T6:T0), is decremented every 49,152 machine cy-
cles, 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 T6:T0) rolls over
from 40h to 3Fh (T6 becomes cleared), it initiates
a reset cycle pulling low the reset pin for typically
30s.
The application program must write in the CR reg-
ister 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 CR register
must be between FFh and C0h (see Table 15, ".
– The WDGA bit is set (watchdog enabled)
– The T6 bit is set to prevent generating an imme-
diate reset
– The T5:T0 bits contain the number of increments
which represents the time delay before the
watchdog produces a reset.
Figure 23. Watchdog Block Diagram
RESET
WDGA
7-BIT DOWNCOUNTER
fCPU
T6
T0
CLOCK DIVIDER
WATCHDOG CONTROL REGISTER (CR)
÷49152
T1
T2
T3
T4
T5
相關(guān)PDF資料
PDF描述
ST72T141K2M6XXX 8-BIT, OTPROM, 8 MHz, MICROCONTROLLER, PDSO34
ST72T141K2M3XXX 8-BIT, OTPROM, 8 MHz, MICROCONTROLLER, PDSO34
ST72T141K2MARE 8-BIT, OTPROM, 8 MHz, MICROCONTROLLER, PDSO34
ST7FL09Y0MATRE 8-BIT, FLASH, 16 MHz, MICROCONTROLLER, PDSO16
ST7FL09Y0MBE 8-BIT, FLASH, 16 MHz, MICROCONTROLLER, PDSO16
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ST72611F1 制造商:STMicroelectronics 功能描述:LOW SPEED USB 8-BIT MCU WITH 3 ENDPOINTS,FLASH MEMORY, - Bulk
ST7263-EMU2 功能描述:仿真器/模擬器 ST7 Emulator Board RoHS:否 制造商:Blackhawk 產(chǎn)品:System Trace Emulators 工具用于評估:C6000, C5000, C2000, OMAP, DAVINCI, SITARA, TMS470, TMS570, ARM 7/9, ARM Cortex A8/R4/M3 用于:XDS560v2
ST7265X-EVAL/MS 制造商:STMicroelectronics 功能描述:ST6 EVAL BD - Bulk
ST7265X-EVAL/PFD 制造商:STMicroelectronics 功能描述:USB FLASH EVAL - Bulk
ST7266 制造商:6940 功能描述:ST7266