User’s Manual
Custom Embedded Solutions
WIN Enterpris es, Inc ., s ales @win-ent.c om
www.win-ent.com
, (978) 688-2000
49
Appendix A: Watchdog Timer Programming Guide
Watchdog timer overview
As systems continually become more complex, the likelihood that a platform will
suffer a hard hang, an operating system (OS) software lockup, or an application
lockup is also becoming more likely. Watchdog timer can be used to monitor
system software operation and take corrective action if the software fails to
function after the programmed period. This section describes the operation of the
watchdog timer and how to program it.
1. Programming the Watchdog Timer
The WIN ENTERPRISES PL-80240 provides a watchdog timer that can reset
the system or activate LAN bypass function. It provides the following function
for user programming:
- Can be enabled and disabled by user ’s program
- Timer can be set from 1 to 255 seconds or 1 to 255 minutes
- Generates a KBRST# (P60) or activate WDTO# (P77) signal if the software
fails to reset the timer when timeout.
2. Watchdog Timer Control Register
The I/O port address of the watchdog timer is 2EH and 2FH, 2EH is the
address port, 2FH is the data port. You must first assign the address of register
by writing address value into address port 2EH, then write/read data to/from
the assigned register through data port 2FH.
Unlock
W83627EHG
Configure the register of
watchdog timer
Downloading the
timeout values
