Nexcom Peak 555A User Manual page 91

Peak 555A User's Guide
e. Clear WDT (this operation should be repeatedly executed before
WDT time out, e.g. if WDT time out set at 16 sec., then to clear WDT,
the instruction
MOV DX, 0F2
IN AL, DX
f. Disable WDT
MOV DX, 70
MOV AL, 7D
OUT DX, AL
MOV DX, 71
IN AL, DX
AND AL, 0F7
OUT DX, AL
MOV BL, AL
MOV DX, 70
MOV AL, 7D
OUT DX, AL
MOV DX, 71
MOV AL, BL
OUT DX, AL
You can also combine programming procedure b+c+d with same subroutine, for
example, set WDT=1 sec, select NMI and go to enable WDT. The instruction as
followings.
MOV AL, 01E
NMI
MOV DX, 0F2
OUT DX, AL
MOV DX, 70
MOV AL, 7D
OUT DX, AL
MOV AL, 01E
MOV DX, 71
OUT DX, AL
Watch Dog Timer
should be executed within 16 sec. repeatedly)
; Directly write to port F2 to set WDT=1 sec, select
and Enable WDT
; Save to CMOS index 7D
A-6