Chapter 3 Software Utilities
PCI-531LF USER
′
S MANUAL
Page:3-11
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 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)
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)
; Disabled Watch Dog
mov
al, 00h
out
dx, al
mov
dx, (800h+67h)
mov
al, 00h
out
dx, al
mov
dx, (800h+68h)
; Clear Status Bit
mov
al, 00h
out
dx, al