Watchdog Timer Overview; Programming The Watchdog Timer - Advantech ASMB-815 Series User Manual

The ASMB-815's watchdog timer can be used to monitor system software operation
and take corrective action if the software fails to function within the programmed
period. This section describes the operation of the watchdog timer and how to pro-
gram it.
A.1

Watchdog Timer Overview

The watchdog timer is built in to the EC controller IT8528E. It provides the following
functions for user programming:
Can be enabled and disabled by user's program

Timer can be set from 1 to 255 seconds

Generates an interrupt or reset signal if the software fails to reset the timer

before time-out
A.2

Programming the Watchdog Timer

The I/O port address of the watchdog timer is as below:
Address
0x57
0x5E
0x5F
Here is an example to step by step program the Watchdog Timer.
Step
00
01
02
03
04
05
06
07
ASMB-815 User Manual
Description
Event - Warm Reset: 0x04
Warm Reset Timer (High BYTE)
Warm Reset Timer (Low BYTE)
Action
Read 0x299 port
Wait IBF clear
Write 0x89 to 0x29A
Wait IBF clear
Write 0x5E to 0x299 port
Wait IBF clear
Write 0x00 to 0x299 port
Wait IBF clear
Write 0x89 to 0x29A
Wait IBF clear
Write 0x5F to 0x299 port
Wait IBF clear
Write 0x64 to 0x299 port
Wait IBF clear
Write 0x89 to 0x29A
Wait IBF clear
96
Based 100ms
Description
Clear I/O port
0x29A, BIT1, = 0
0x29A, BIT1, = 0
0x29A, BIT1, = 0
Set 10 sec (high byte)
0x29A, BIT1, = 0
0x29A, BIT1, = 0
0x29A, BIT1, = 0
Set 10 sec (low byte)
0x29A, BIT1, = 0
0x29A, BIT1, = 0