What is a watch-dog timer, its use and typical application for an embedded system.

Mumbai University > Electronics Engineering > Sem 6 > Embedded System and RTOS

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Watchdog Timer

  • The watchdog timer is a simple electronic device that is responsible to resetting the microcontroller or microprocessor for invalid software status.
  • Generally a microcontroller is programmed with software that contains several loops and number of subroutines that direct variety of activities.
  • If any reason, if the loop is fail to execute, then it finds and resets the device at starting or top of the loop.
  • The watchdog timer is a simple counter that gives pulses to restart the MCU.
  • This timer in an embedded system consists of separate clock frequency based on the MCU to generate the clock pulses by setting the time through the WDTCSR register.
  • The output of the watchdog timer is given directly to the microcontroller reset signal. Whenever the watchdog counter register is not get cleared, then it immediately forces to restart the microprocessor or controller.
  • Many of the microcontrollers or processors have inbuilt watchdog timer circuit for detecting the system malfunctions.
  • There are of two types such as:

a. Internal Watchdog Timer

b. External Watchdog Timer

Advantages of Watchdog Timers:

  • Resets automatically without human intervention.
  • Detects the errors in the program and reboot the system
  • Cost sensitive
  • Saves the time and money
  • No need to place the employers to monitor the software debugs.
  • Increases the system performance.
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