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14628 Central Blvd,
Chino, CA91710
tel:909.597.7588, fax:909.597.1939
PC6172
17” industrial Core 2 Duo Panel PC
3-8 Watchdog Timer Configuration
The Watch-dog Timer has a programmable time-out ranging from 1 to 255 minutes with one minute
resolution, or 1 to 255 seconds with 1 second resolution. The units of the WDT timeout value are
selected via bit[7] of the WDT_TIMEOUT register, which is located on I/O Port address 0x865h. The
WDT time-out value is set through the WDT_VAL Runtime register, which is located on I/O Port
address 0x866h. Setting the WDT_VAL register to 0x00 disables the WDT function Setting the
WDT_VAL to any other non-zero value will cause the WDT to reload and begin counting down from the
value loaded. Setting the Register located on I/O address 0x867h and 0x868h as 00h to finish timer
configuration.
Example Program
Example Code: (1)
; ------------------------------------------------------------------------------------------------
; Enable Watch-Dog Timer
;-------------------------------------------------------------------------------------------------
mov dx, (800h+65h) ; Time counting Unit minute or second
mov al, 80h ; al = 00h : minute, or al = 80h : second
out dx, al
mov dx, (800h+66h)
mov al, 20 ; al = Watch Dog Timer Second (s) , 20 sec(s)
ou dx, al
mov dx, (800h+67h)
mov al, 00h
out dx, al
mov dx, (800h+68h) ; Start Watch Dog Timer
mov al, 00h
out dx, al