Acrosser AR-B9612 - Manual (Page 16)

AR-B9612 User’s Guide
2-11
2.8 WATCH-DOG TIMER
The watchdog timer is a circuit that may be used from your
program software to detect crashes or hang-ups.
Once you have enabled the watchdog timer, your program must
trigger the watchdog timer every time before it times-out.
After you trigger the watchdog timer, it will be set to zero and
start to count again. If your program fails to trigger the
watchdog timer before time-out, it will generate a reset pulse to
reset the system.
The I/O port address of watchdog timer is located at 214Hex or
215Hex. The factor of the watchdog timer time-out constant
is approximately 1.6 seconds.
2.8.1 Enabled the Watchdog Timer
To enable the watchdog timer, you have to output a byte of timer
factor to the watchdog address. The following is a BASICA
program:
1000 REM Points to I/O port address
1010 WD_REG% = I/O_PORT
1020 REM Timer factor =80H
1030 TIMER_FACTOR% = &H80
1040 REM Output factor to watchdog
1050 OUT WD_REG%, TIMER_FACTOR%
,etc.