What is a watchdog timer and why is it used?

A watchdog timer (WDT) is a hardware timer that resets the system if not periodically refreshed by software, used to recover from software faults. Operation: Timer counts down from a preset value. Software must 'kick' or 'feed' the watchdog before timeout. If software hangs or crashes, timeout occurs and system resets. Use cases: Recover from infinite loops or deadlocks. Handle software bugs in deployed systems. Ensure system availability in critical applications. Meet safety requirements (automotive, medical). Implementation considerations: Set appropriate timeout period. Kick from main loop or dedicated task. Consider windowed watchdog for better fault detection. Disable during debugging. Some systems use multiple watchdogs (hardware and software).