Table of Contents
Advertisement
Chapter 3 Software Configuration
3-7. 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). This is defined at
I/O port 444H and 448H. When you want to enable the watchdog timer,
please write I/O port 444H and 448H, then the system will either reset itself
or perform the NMI function. If you want to stop watchdog timer, you can
read I/O port 440H, then timer will stop count.
In PSB-701LF watchdog function, You must write your program so when it
writes I/O port address 444H and 448H for enable 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 of system reset enable program:
MOV
MOV
OUT
Watchdog of NMI enable program:
MOV
MOV
OUT
Stop Watchdog Timer program:
MOV
In
The Watchdog Timer control table is as follows:
Level
1
2
3
4
5
6
7
8
Page:3-10
AX, 0FH (choose the values you need; start from 0)
DX, 0444H
DX, AX
AX, 0FH (choose the values you need; start from 0)
DX, 0448H
DX, AX
DX, 0440H
AX , DX
Value
Time/sec
F
0
E
8
D
16
C
24
B
32
A
40
9
48
8
56
Level
Value
9
7
10
6
11
5
12
4
13
3
14
2
15
1
16
0
PSB-701LF USER
Time/sec
64
72
80
88
96
104
112
120
'
S MANUAL
Advertisement
Table of Contents
