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參數資料
| 型號： | W78LE54P-24 |
| 廠商： | WINBOND ELECTRONICS CORP |
| 元件分類： | 微控制器/微處理器 |
| 英文描述： | 8-BIT MTP MICROCONTROLLER |
| 中文描述： | 8-BIT, FLASH, 24 MHz, MICROCONTROLLER, PQCC44 |
| 封裝： | PLASTIC, LCC-44 |
| 文件頁數： | 7/22頁 |
| 文件大小： | 308K |
| 代理商： | W78LE54P-24 |
Preliminary W78LE54
Publication Release Date: February 1999
- 7 -
Revision A1
Watchdog Timer
The Watchdog timer is a free-running timer which can be programmed by the user to serve as a
system monitor, a time-base generator or an event timer. It is basically a set of dividers that divide
the system clock. The divider output is selectable and determines the time-out interval. When the
time-out occurs a system reset can also be caused if it is enabled. The main use of the Watchdog
timer is as a system monitor. This is important in real-time control applications. In case of power
glitches or electro-magnetic interference, the processor may begin to execute errant code. If this is
left unchecked the entire system may crash. The watchdog time-out selection will result in different
time-out values depending on the clock speed. The Watchdog timer will de disabled on reset. In
general, software should restart the Watchdog timer to put it into a known state. The control bits that
support the Watchdog timer are discussed below.
Watchdog Timer Control Register
Bit:
7
6
5
4
-
3
-
2
1
0
ENW
CLRW
WIDL
PS2
PS1
PS0
Mnemonic: WDTC
Address: 8FH
ENW : Enable watch-dog if set.
CLRW : Clear watch-dog timer and prescaler if set. This flag will be cleared automatically
WIDL : If this bit is set, watch-dog is enabled under IDLE mode. If cleared, watch-dog is disabled
under IDLE mode. Default is cleared.
PS2, PS1, PS0 : Watch-dog prescaler timer select. Prescaler is selected when set PS2~0 as follows:
PS2 PS1 PS0
0 0 0
0 1 0
0 0 1
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
PRESCALER SELECT
2
4
8
16
32
64
128
256
The time-out period is obtained using the following equation:
1
OSC
2
PRESCALER 1000 12 mS
14
×
×
Before Watchdog time-out occurs, the program must clear the 14-bit timer by writing 1 to WDTC.6
(CLRW). After 1 is written to this bit, the 14-bit timer, prescaler and this bit will be reset on the next
instruction cycle. The Watchdog timer is cleared on reset.
相關PDF資料 |
PDF描述 |
|---|---|
| W78LE54-24 | 8-BIT MTP MICROCONTROLLER |
| W78LE54 | 8-BIT MTP Monitor Microcontroller(多次可編程的8位的監視微控制器) |
| W78LE58P-24 | 8-BIT MICROCONTROLLER |
| W78LE58 | 8-BIT MICROCONTROLLER |
| W78LE58-24 | 8-BIT MICROCONTROLLER |
相關代理商/技術參數 |
參數描述 |
|---|---|
| W78LE58 | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8-BIT MICROCONTROLLER |
| W78LE58_06 | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8-BIT MICROCONTROLLER |
| W78LE58-24 | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8-BIT MICROCONTROLLER |
| W78LE58F-24 | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8-BIT MICROCONTROLLER |
| W78LE58P-24 | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8-BIT MICROCONTROLLER |
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