看门狗分硬件看门狗和软件看门狗。硬件看门狗是利用一个定时器电路，其定时输出连接到电路的复位端，程序在一定时间范围内对定时器清零(俗称“喂狗”)，因此程序正常工作时，定时器总不能溢出，也就不能产生复位信号。如果程序出现故障，不在定时周期内复位看门狗，就使得看门狗定时器溢出产生复位信号并重启系统。-Watchdog Watchdog hardware and software watchdog points. Is to use a hardware watchdog timer circuit, the timing output terminal connected to the reset circuit, the program within a certain time on the timer clear (commonly known as " feed the dog" ), the normal procedure, the timer can not overflow, it can not generate reset signal. If the program fails, do not reset the watchdog timer cycle, it makes the reset watchdog timer overflow signal and reboot the system.