AXIOMTEK UST510-52B-FL Series, User Manual

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UST510-52B-FL Series u
ser’s Manual
Watchdog Timer 61
APPENDIX A
WATCHDOG TIMER
About Watchdog Timer
Software stability is a major issue in most applications. Some embedded systems are not
watched by humans for 24 hours. It is usually too slow to wait for someone to reboot when a
computer hangs. The system needs to be able to reset automatically when things go wrong.
The watchdog timer gives us solutions in this regard.
The watchdog timer is a counter that triggers a system to reset when it counts down to zero
from a preset value. The software starts the counter with an initial value and must reset it
periodically. If the counter ever reaches zero, it means the software has crashed, the system
will reboot.
How to Use the Watchdog Timer
The user can configure the watchdog timer using the watchdog function included in
the AXVIEW2.0 software developed by Axiomtek or using the debug.exe software
released by Microsoft.
NOTE: The related tool for setting WDT will not be available on the official downloads area.
If you need any tool, please contact Axiomtek
’s local distributor immediately.
Sample Program
The below sample code shows how to use DEBUG.exe in DOS mode to configure WDT
function.
Enable watchdog timer
STEP Sample code Note
1. Enter configuration mode O 2E 87
O 2E 87
Un-lock super I/O
Un-lock super I/O
2. Select logic device O 2E 07
O 2F 08
Select logic register
Switch to WDT device
3. Enable WDT device O 2E 30
O 2F 01
Select register
Enable WDT
4. Set time unit O 2E F0
O 2F M
Select logic register
M = 08h (Minute) ,
M = 00h (Second)
5. Set timer O 2E F1
O 2F 0A
Select logic register
Set timer (where 0A (hex) = 10sec)