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Watch Dog Function:
Support 1~255 second or minute selectable timeout interval.
Watch Code:
1) Enter configuration mode:
MOV DX,4EH
MOV AL,87H
OUT DX,AL
OUT DX,AL
2) Logical Device 8
MOV DX,4EH
MOV AL,07H
OUT
DX,AL
MOV DX,2FH
MOV AL,08H
OUT DX,AL
3) Enable WDTO# and set to KBRST#
MOV DX,2EH
MOV AL,30H
OUT DX,AL
MOV DX,2FH
MOV AL,01H
OUT DX,AL
MOV DX,2EH
MOV AL,F7H
OUT DX,AL
MOV DX,2FH
IN
DX,AL
AND AL,0F7H
OUT DX,AL
;CR F6h: bit0~7 fill in counter time
;CR F5h: bit1 fill in 1(Enable WDTO# & KBRST#)
4) Exit configuration mode:
MOV DX,4EH
MOV AL,0AAH
OUT DX,,AL
;point to Logical Device Number Reg.
;select Logical Device 8
;CR 30h: bit0 fill in 1
; CR F7h: bit4 fill in 0(clear event)
Bit 3 (0: Second Mode,1:Minute Mode)
Hardware Setup
2-21
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