Watchdog Timer Configuration - Protech Systems PMB-531LF User Manual

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)
mov al,80h
out dx,al
mov dx,(800h + 66h) ;
mov al,20
out dx,al
mov dx,(800h + 67h)
mov al,00h
out dx,al
mov dx,(800h + 68h)
mov al,00h
out dx,al
(2)
;--------------------------
Disable Watch-Dog Timer
;--------------------------
mov dx,(800h + 66h)
PMB-531LF USER
;Time counting Unit minute or second
;al = 00h : unit minute
;al = 80h : unit second
;al = Watch dog Timer Second(s), 20 sec(s)
;Start Watch Dog Timer
;Disable Watch Dog Timer
'
S MANUAL
Chapter 3 Software Configuration
Page:3-11