Appendix A: Programming Watchdog Timer
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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, see
folder under Driver and Utility on the
