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參數(shù)資料
| 型號： | W79E532A40DN |
| 廠商： | WINBOND ELECTRONICS CORP |
| 元件分類： | 微控制器/微處理器 |
| 英文描述： | 8-BIT MICROCONTROLLER |
| 中文描述： | 8-BIT, FLASH, 40 MHz, MICROCONTROLLER, PDIP40 |
| 封裝： | DIP-40 |
| 文件頁數(shù)： | 47/77頁 |
| 文件大小： | 523K |
| 代理商： | W79E532A40DN |
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W79E532/W79L532
Publication Release Date: November 21, 2005
- 47 -
Revision A5
The Watchdog timer should first be restarted by using RWT. This ensures that the timer starts from a
known state. The RWT bit is used to restart the watchdog timer. This bit is self clearing, i.e. after
writing a 1 to this bit the software will automatically clear it. The watchdog timer will now count clock
cycles. The time-out interval is selected by the two bits WD1 and WD0 (CKCON.7 and CKCON.6).
When the selected time-out occurs, the Watchdog interrupt flag WDIF (WDCON.3) is set. After the
time-out has occurred, the watchdog timer waits for an additional 512 clock cycles. If the Watchdog
Reset EWT (WDCON.1) is enabled, then 512 clocks after the time-out, if there is no RWT, a system
reset due to Watchdog timer will occur. This will last for two machine cycles, and the Watchdog timer
reset flag WTRF (WDCON.2) will be set. This indicates to the software that the watchdog was the
cause of the reset.
When used as a simple timer, the reset and interrupt functions are disabled. The timer will set the
WDIF flag each time the timer completes the selected time interval. The WDIF flag is polled to detect a
time-out and the RWT allows software to restart the timer. The Watchdog timer can also be used as a
very long timer. The interrupt feature is enabled in this case. Every time the time-out occurs an
interrupt will occur if the global interrupt enable EA is set.
The main use of the Watchdog timer is as a system monitor. This is important in real-time control
applications. In case of some power glitches or electro-magnetic interference, the processor may
begin to execute errant code. If this is left unchecked the entire system may crash. Using the
watchdog timer interrupt during software development will allow the user to select ideal watchdog
reset locations. The code is first written without the watchdog interrupt or reset. Then the watchdog
interrupt is enabled to identify code locations where interrupt occurs. The user can now insert
instructions to reset the watchdog timer which will allow the code to run without any watchdog timer
interrupts. Now the watchdog timer reset is enabled and the watchdog interrupt may be disabled. If
any errant code is executed now, then the reset watchdog timer instructions will not be executed at
the required instants and watchdog reset will occur.
The watchdog time-out selection will result in different time-out values depending on the clock speed.
The reset, when enabled, will occur 512 clocks after the time-out has occurred.
Table 9. Time-out values for the Watchdog timer
WD1
WD0
WATCHDOG
INTERVAL
2
17
2
20
2
23
2
26
NUMBER OF
CLOCKS
TIME
@ 1.8432 MHZ
TIME
@ 10 MHZ
TIME
@ 25 MHZ
0
0
131072
71.11 mS
13.11 mS
5.24 mS
0
1
1048576
568.89 mS
104.86 mS
41.94 mS
1
0
8388608
4551.11 mS
838.86 mS
335.54 mS
1
1
67108864
36408.88 mS
6710.89 mS
2684.35 mS
The Watchdog timer will de disabled by a power-on/fail reset. The Watchdog timer reset does not
disable the watchdog timer, but will restart it. In general, software should restart the timer to put it into
a known state.
The control bits that support the Watchdog timer are discussed below.
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| W79L532 | 8-BIT MICROCONTROLLER |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| W79E532A40FL | 功能描述:IC MCU 8-BIT 128KB FLASH 44-QFP RoHS:是 類別:集成電路 (IC) >> 嵌入式 - 微控制器， 系列:W79 標(biāo)準(zhǔn)包裝:250 系列:56F8xxx 核心處理器:56800E 芯體尺寸:16-位 速度:60MHz 連通性:CAN，SCI，SPI 外圍設(shè)備:POR，PWM，溫度傳感器，WDT 輸入/輸出數(shù):21 程序存儲器容量:40KB（20K x 16） 程序存儲器類型:閃存 EEPROM 大小:- RAM 容量:6K x 16 電壓 - 電源 (Vcc/Vdd):2.25 V ~ 3.6 V 數(shù)據(jù)轉(zhuǎn)換器:A/D 6x12b 振蕩器型:內(nèi)部 工作溫度:-40°C ~ 125°C 封裝/外殼:48-LQFP 包裝:托盤 配用:MC56F8323EVME-ND - BOARD EVALUATION MC56F8323 |
| W79E532A40FN | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8-BIT MICROCONTROLLER |
| W79E532A40PL | 功能描述:IC MCU 8-BIT 128KB FLASH 44-PLCC RoHS:是 類別:集成電路 (IC) >> 嵌入式 - 微控制器， 系列:W79 標(biāo)準(zhǔn)包裝:250 系列:56F8xxx 核心處理器:56800E 芯體尺寸:16-位 速度:60MHz 連通性:CAN，SCI，SPI 外圍設(shè)備:POR，PWM，溫度傳感器，WDT 輸入/輸出數(shù):21 程序存儲器容量:40KB（20K x 16） 程序存儲器類型:閃存 EEPROM 大小:- RAM 容量:6K x 16 電壓 - 電源 (Vcc/Vdd):2.25 V ~ 3.6 V 數(shù)據(jù)轉(zhuǎn)換器:A/D 6x12b 振蕩器型:內(nèi)部 工作溫度:-40°C ~ 125°C 封裝/外殼:48-LQFP 包裝:托盤 配用:MC56F8323EVME-ND - BOARD EVALUATION MC56F8323 |
| W79E532A40PN | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8-BIT MICROCONTROLLER |
| W79E548 | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8-BIT MICROCONTROLLER |
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