Watchdog Timer

A safety timer that resets the microcontroller if the software stops responding.

Easy

The program must "kick" (refresh) the watchdog regularly. If code hangs — an infinite loop, a deadlock, a crashed peripheral — the watchdog times out and resets the chip.

wdt_enable(WDTO_2S);     // AVR: reset if not refreshed within 2 s
while (1) {
    do_work();
    wdt_reset();         // "I'm still alive"
}

Kick it only from the main loop when everything is healthy — never from a timer interrupt, which could keep running while the main code is stuck.

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