Appendix A Watchdog Timer; About Watchdog Timer; How To Use Watchdog Timer - AXIOMTEK IMB520R User Manual

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
computer hangs. The systems need to be able to reset automatically when things go wrong.
The watchdog timer gives us that solution.
The watchdog timer is a counter that triggers a system 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 which means the software has crashed, the
system will reboot.

How to Use Watchdog Timer

Start

Un-Lock WDT:

Select Logic device:

Set Second or Minute:

Set base timer:

WDT counting re-set timer:

IF No re-set timer:
;IF to disable WDT:
 Timeout Value Range
 1 to 255
 Minute / Second
Watchdog Timer
IMB520R / 521R LGA1151 ATX Motherboard
Watchdog Timer
O 2E 87 ; Un-lock super I/O
O 2E 87 ; Un-lock super I/O
O 2E 07
O 2F 08
O 2E F0
O 2F N ; N=00 or 08 (See
O 2E F1
; M=00,01,02,...FF(Hex) ,Value=0 to 255
O 2F M
O 2E F1
; M=00,01,02,...FF (See
O 2F M
; WDT time-out, generate RESET
O 2E 30
O 2F 00 ; Can be disabled at any time
Appendix A
Note below)
Note below)
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