Watchdog Timer Programming Example - Advantech TPC-1560 User Manual

B.1 Watchdog timer programming example
The watchdog timer built in the TPC-1560 is a useful aid to reduce
system down time-especially for those operating systems not reliable
enough. There is a counter inside the watchdog timer. If the system
does not constantly clear the counter within the timeout period, the
watchdog timer would initialize a system reset.
The following example program in assembly language gives hint to
utilize the watchdog timer under operating systems such as DOS,
Windows 9x/NT, etc.
Step 1: activate the watchdog timer
mov
in
and
out
Step 2: clear the watchdog timer
mov
in
or
out
Step 3: re-trigger the watchdog timer
If the timer will not count the GP07 is kept high. To re-trigger the watch-
dog timer:
mov
in
and
out
Notice:
4 0 TPC-1260 User's Manual
dx, 404Ch
al, dx
al, NOT 80h
dx, al
dx, 404Ch
al, dx
al, 80h
dx, al
dx, 404Ch
al, dx
al, NOT 80h
dx, al
the utility to enable/disable the watchdog timer under
Windows CE is built in the Advantech Windows CE
for TPC-1560.
; GPO7 to low
; GPO7 to high
; GPO7 to low