Watchdog is timer hardware which is incorporated in almost every microcontroller. The watchdog timer is used to detect any endless loop in the user program. Watchdog is basically a counter, that counts from the initial value to zero. The user can select the initial counter value and set the watchdog configuration. After initialization of watchdog timer, the user program should reconfigure or reset the watchdog timer before timeout of watchdog timer. If watchdog timer counter timeout arrives before the completion of user program, will results in restart of program.