Watchdog timer what is

If a watchdog were to fail along with the MCU perhaps the entire PCB burns out , mechanical hardware fail safes might be the next step for ensuring safety. Watchdog timer says the programmer that, you have to reset me continuously otherwise I will reset the whole system after reaching to my timeout.

If the system stuck-up somewhere, the reset instruction execution missed and then the Watchdog timer will reset the system. Your email address will not be published. Comments Can u explain in more with perfect example…. Leave a Reply Cancel reply Your email address will not be published. However, unlike the window and the timeout modes, this mode relies on data communication between the MCU and WDT, which makes operation more complex.

In the following, we will bring up points that should be considered before deciding which WDT to choose. The reason is that an external WDT adds an extra layer of safety to critical systems. An independently operating WDT is the only way to resolve such concerns.

Redundancy is considered vital in maintaining system safety. And an external WDT can provide the required redundancy. Automotive devices are devices where MCU failure or malfunction could lead to life-threatening accidents. In water heaters and kitchen stoves, MCU failure or malfunction poses a fire risk.

In systems that impact human life or in applications where malfunction of electronic control can cause serious accidents, an external WDT is required to ensure sufficient redundancy. Again, like applications that require WDTs, some situations may require a WDT to provide the level of safety that is required or deemed necessary to implement.

Embedded System Tutor. Watchdog Timer in Embedded System. After reading this blog below questions will get solved regarding watchdog timer what is watchdog timer?

Why watchdog timer is important? How does watchdog timer works? How to use watchdog timer in embedded system? Introduction: Watchdog timer is a piece of hardware in micro-controller. Watchdog timer is used to generates system reset if system gets stuck somewhere i. Watchdog is safety mechanism in embedded system which makes your system reliable, but it depends on how you make use of watchdog timer. Watchdog is basically a counter, which starts from counting zero and reaches to a certain value.

If counter reaches to certain value then watchdog hardware will generates a watchdog reset. To avoid system reset, software needs to kick the watchdog i. In case software stuck into endless loop it system will not able to kick the watchdog hence counter reaches to certain value and resets the system.

If your system if performing 3 tasks periodically and to perform 3 tasks is takes ms. Then timeout time is considered as ms considering worst case scenario , counter value is calculated with respect to ms and loaded into watchdog. Following figures shows watchdog hardware. Input to watchdog hardware is clock.

Based on every clock tick watchdog internal counter increments. Then there is comparator which compares count value with loaded count value timeout value and if count matches watchdog hardware generates and reset signal. Consider a system in watchdog is working on 4 kHz clock.