User manual

AIMB-556 User Manual 96
Appendix AProgramming the Watchdog
Timer
A.1 Introduction
The AIMB-556’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 program it.
A.1.1 Watchdog timer overview
The watchdog timer is built in to the W83627HG super I/O controller. It
provides the following user programmable functions:
• Can be enabled and disabled by user’s program
• Timer can be set from 1 to 255 seconds or 1 to 255 minutes
• Generates an interrupt or reset signal if the software fails to reset the
timer before time-out
A.1.2 Programming the Watchdog Timer
The I/O port address of the watchdog timer is 2E (hex) and 2F (hex). 2E
(hex) is the address port. 2F (hex) is the data port. You must first write an
address value into address port 2E (hex), then write/read data to/from the
assigned register through data port 2F (hex).