Software Configuration
CommPlete 4000 Server SBC, Model IPC-623C
45
3-5. Watchdog Timer Configuration
The watchdog timer does not run constantly. It must be started
in DOS Debug mode or from another application program,
customized for this purpose, that runs on the system. The
watchdog timer is especially useful for remote rebooting of the
PC.
The watchdog timer is defined at I/O port 0443H. To enable the
watchdog timer, write I/O port 0443H, then the system will reset
itself. To disable the function, write I/O port 0441H and the
system will stop the Watchdog timer.
Since the timer’s intervals have a tolerance of 25%, you should
specify that the timer be refreshed about once every second. To
program your watch timer, follow these steps:
Watchdog enable program:
MOVAX, 000FH (choose the values you need; start from 0)
MOVDX, 0443H
OUTDX, AX
Watchdog disable program:
MOVAX, 000FH (this value can be ignored)
MOVDX, 0441H
OUTDX, AX
The Watchdog Timer control table is as follows:
Level
Value Time/sec Level
Value
Time/sec
1
F
0
9
7
64
2
E
8
10
6
72
3
D
16
11
5
80
4
C
24
12
4
88
5
B
32
13
3
96
6
A
40
14
2
104
7
9
48
15
1
112
8
8
56
16
0
120
