Advantech SOM-4450 CPU System On Module SOM-4450 ETX User Manual
Page 27
Appendix A Programming the Watchdog Timer 21
After data entry, your program must refresh the watchdog timer by
rewriting the I/O port 443 (hex) while simultaneously setting it. When
you want to disable the watchdog timer, your program should read I/O
port 443 (hex).
The following example shows how you might program the watchdog
timer in BASIC:
10
REM Watchdog timer example program
20
OUT &H443, data REM Start and restart the watchdog
30
GOSUB 1000 REM Your application task #1,
40
OUT &H443, data REM Reset the timer
50
GOSUB 2000 REM Your application task #2,
60
OUT &H443, data REM Reset the timer
70
X=INP (&H443) REM, Disable the watchdog timer
80
END
1000
REM Subroutine #1, your application task
•
•
•
•
•
•
1070
RETURN
2000
REM Subroutine #2, your application task
•
•
•
•
•
•
2090
RETURN