34 PCA-6155 User's Manual
Programming the Watchdog Timer
If you decide to program the watchdog timer, you must write data
to I/O port 443 (hex). The output data is a value timer. You can
write from 01 (hex) to 3E (hex), and the related timer is 1 sec. to
63 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 043 (hex).
The following proceedure is a program for the watchdog timer:
Step 1
Out 443h, data REM Start and reset
the watchdog timer
Step 2
your application program task #1
Step 3
out 443h, data REM Reset the timer
Step 4
your application program task #2
Step 5
out 443h, data REM Reset the timer
Step 6
in 043h, REM Disable the watchdog
timer
Data Values
01
1 sec.
02
2 sec.
03
3 sec.
04
4 sec.
.
.
.
.
.
.
.
.
3E
63 sec.
Содержание PCA-6155
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