A
watchdog timer is a
safety feature found in
microprocessor-controlled
electronics that prevents runaway software from halting a system which experiences a
critical or
fatal system fault. When it times out, it stops a microprocessor from executing meaningless
code, a situation that arises from an
electrical or
programming error. More specifically, if the
software is not being executed properly, it fails to clear the watchdog timer; if the watchdog timer is not cleared for a specified
interval, the watchdog timer causes the microprocessor to
reboot and execute software from a designated location.
A watchdog timer is most useful for mission critical systems that must remain in continuous operation without human intervention, or in environments where personnel are not normally present or readily available to intervene should a system failure occur. This hardware-based feature is generally application-specific, and is often adequate safety in lieu of a redundant system.