An external watchdog timer (WDT), Maxim MAX6373<ref name="MAX6373">https://www.maximintegrated.com/en/products/power/supervisors-voltage-monitors-sequencers/MAX6373.html</ref>) , is connected to the PORSTn signal. During normal operation, the microprocessor should repeatedly toggle the watchdog input WDI before the selected watchdog timeout period elapses to demonstrate that the system is processing code properly. If the μP does not provide a valid watchdog input transition before the timeout period expires, the supervisor asserts a watchdog (WDO) output to signal that the system is not executing the desired instructions within the expected time frame. The watchdog output pulse is used to reset the μP.

The MAX6373 watchdog timer (WDT) timeout is pin-selectable. It can be configured through the WD_SET0 (J2.100), WD_SET1 (J2.98) and WD_SET2 (J2.96) signals. As a By default, they are configured as follows: