Chapter 3 Software Configuration
Page:3-10
Prox-1550 USER
′
S MANUAL
3-6. WATCHDOG TIMER CONFIGURATION
This board has watchdog timer function for monitoring whether the system is
still work or not after a period of time. The user can select watchdog timer
to system reset or NMI (Non Maskable interrupt) depending on the jumper
set in JP6 as described in chapter 2. This is defined at I/O port
443H
. When
you want to enable the watchdog timer, please write I/O port
443H
, then the
system will either reset itself or perform the NMI function. Likewise, when
you want to disable the function, write I/O port
441H
, the system will run
the command to stop the Watchdog function.
The Prox-1550 watchdog function, You must write your program so when it
writes I/O port address 443 for enable watchdog and write I/O port address
441 for disable watchdog. The timer
'
s intervals have a tolerance of 25% so
you should program an instruction that will refresh the timer about every
second.
The following program shows you how to program the watch timer in your
program.
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
Summary of Contents for ProX-1550
Page 1: ...USER S MANUAL ...
Page 60: ...Chapter 3 Software Configuration Prox 1550 USER S MANUAL Page 3 11 ...
Page 64: ...Chapter 4 Green PC Function Page 4 4 Prox 1550 USER S MANUAL ...
Page 92: ...Chapter 5 Award BIOS Setup Page 5 28 Prox 1550 USER S MANUAL ...
Page 98: ...Appendix B Technical Summary Page B 2 Prox 1550 USER S MANUAL BLOCK DIAGRAM ...