Electronic – Microcontroller’s watchdog


Can anyone explain a little more about watchdogs, specifically in the circuitry level?

If there is some kind of problem in the chip, how can I guarantee that it will be kept running? It is implemented in a different silicon and later attached to the main chip circuit to avoid temperature problems? Which kind of interface circuit it is commonly used to avoid counting/resetting errors? It is common to implement any kind of redundancy?

Best Answer

The watchdog is just a timer on the same die as the rest of the microcontroller. It's mainly meant to catch software errors, there are no precautions for a malfunction of the watchdog itself. Typically one would reset the watchdog timer in the program's main loop. If for some reason the main loop will no longer be executed the controller will reset.
If you don't trust the microcontroller hardware you can always add an external watchdog IC.