If an Arduino program crashes in the forest, will it make a sound? Unfortunately not. No blue screen of death, nor jarring squawk will alert you to the program’s doom. It will typically just quietly and unobtrusively stop running whatever robot, keypad or front door it is supposed to be looking after. In this article, I’ll show you how to use the watchdog timer to help track down the bug causing the lockup. But first, there’s a quick review of the watchdog timer itself for those new to the game.