Intel PMB-531LF user manual Watchdog Timer Configuration, Example Code

Chapter 3 Software Configuration

3-9. 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 Code

(1)
;--------------------------
Enable Watch-Dog Timer
;--------------------------
mov dx,(800h + 65h)	;Time counting Unit minute or second
mov al,80h	;al = 00h : unit minute
out dx,al	;al = 80h : unit second
mov dx,(800h + 66h) ;
mov al,20	;al = Watch dog Timer Second(s), 20 sec(s)
out 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
(2)
;--------------------------
Disable Watch-Dog Timer
;--------------------------
mov dx,(800h + 66h)	;Disable Watch Dog Timer
PMB-531LF USER′S MANUAL	Page:3-11