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Appendix A: Programming Watchdog Timer
A watchdog timer is a piece of hardware that can be used to automatically detect system anomalies and
reset the processor in case there are any problems. Generally speaking, a watchdog timer is based on a
counter that counts down from an initial value to zero. The software selects the counter's initial value and
periodically restarts it. Should the counter reach zero before the software restarts it, the software is
resumed to be malfunctioning and the processor's reset signal is asserted. Thus, the processor will be
restarted as if a human operator had cycled the power.
Watchdog Timer
Clock
To execute the utility: enter the number of seconds to start countdown before the system can be reset.
Press start to start the counter and stop to stop the counter.
wd_tst --swt xxx (Set Watchdog Timer 1-255 seconds)
wd_tst[*] --start (Start Watchdog Timer)
wd_tst --stop (Stop Watchdog Timer)
For a reference utility that contains sample code for watchdog function programming, please visit
http://www.lannerinc.com/support/download-center/drivers, enter the product category and download
the utility package.
Reset
Restart
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Processor
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