IBM CI5VGM Series user manual Watchdog Timer Configuration, Enabling Watchdog, Disabling Watchdog

Chapter 2 Installations

Watchdog Timer Configuration

The function of the watchdog timer is to reset the system automatically and is defined at I/O port 0443H. To enable the watchdog timer and allow the system to reset, write I/O port 0443H. To disable the timer, write I/O port 0441H for the system to stop the watchdog function. The timer has a tolerance of 20% for its intervals.

The following describes how the timer should be programmed.

Enabling Watchdog:
MOV	AX, 000FH (Choose the values from 0)
MOV	DX, 0443H
OUT	DX, AX
Disabling Watchdog
MOV	AX, 00FH (Any value is fine.)
MOV	DX, 0441H
OUT	DX, AX
		WATCHDOG TIMER CONTROL TABLE
Level		Value		Time/sec	Level	Value		Time/sec
1		F	0		9	7	16
2		E	2		10	6	18
3		D	4		11	5	20
4		C	6		12	4	22
5		B	8		13	3	24
6		A	10		14	2	26
7		9	12		15	1	28
8		8	14		16	0	30

CI5VGM User’s Manual 37