Watchdog Timers

• To improve reliability it is very useful to have a support circuit that helps detect when your microprocessor has stopped doing its job.

  • Microprocessor periodically and regularly asserts some RESET/ signal attached to a watchdog circuit.
  • watchdog circuit timer resets to some number upon a reset.
  • counts down every clock cycle.
  • watchdog asserts some restart signal to the microprocessor when timer reaches zero.