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A.1 Programming the Watchdog Timer
In order to program the watchdog timer, you must write a program
which writes I/O port address 443 (hex). The output data is a value of
time interval. The value range is from 01 (hex) to 3F (hex), and the
related time interval is 1 sec. to 62 sec.
Data
Time Interval
0 1
1 sec.
0 2
2 sec.
0 3
3 sec.
0 4
4 sec.
.
.
.
3 F
62 sec.
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:
1 0
REM Watchdog timer example program
2 0
OUT &H443, data
watchdog
3 0
GOSUB 1000
4 0
OUT &H443, data
5 0
GOSUB 2000
6 0
OUT &H443, data
7 0
X=INP (&H443)
8 0
END
1000 REM
.
.
.
1070 RETURN
2000 REM
.
.
.
2090 RETURN
106 PPC-105 User's Manual
REM Start and restart the
REM Your application task #1
REM Reset the timer
REM Your application task #2
REM Reset the timer
REM Disable the watchdog timer
Subroutine #1, you application task
Subroutine #2, you application task
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