Watchdog timer

A watchdog timer is a component of an electronic system that makes sure the system is operating properly. These components can either be done as a piece of hardware or as software. Depending on the intended use, they either signal that a system is not working properly, or they make a system work properly again. A watchdog timer may cause a system to reset itself to its initial state.

Watchdog Timer Media

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  A watchdog timer integrated circuit (Texas Instruments TPS3823). One pin receives the timer restart ("kick") signal from the computer; another pin outputs the timeout signal.

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  Watchdog timers are essential in remote, automated systems such as this Mars Exploration Rover

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  Some watchdog timers only allow kicks during a time window. Kicks occurring outside the window have no effect on the timer and may be treated as faults.

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  Screenshot of wdctl, a program that shows watchdog status

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  Block diagram of a simple, single-stage watchdog timer. The common clock is characteristic of basic watchdog circuits found in simple microcontrollers.

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  A three-stage electronic watchdog timer. Each stage triggers one or more corrective actions and starts the next stage. The final stage restarts the computer.

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  Block diagram of 2-stage watchdog timer.