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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
presumed 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.
For sample watchdog code, please go to the Lanner Support Website at
http://www.lannerinc.com/download-center/
and browse the download center.
To execute the sample code: enter the number of seconds to start count down before the system can be
reset. Press start to start the counter and stop to stop the counter..
Dwd_tst --swt xxx (Set Watchdog Timer 1-255 seconds)
wd_tst[*] --start (Start Watchdog Timer)
wd_tst --stop (Stop Watchdog Timer)
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