在由单片机构成的微型计算机系统中，由于单片机的工作常常会受到来自外界电磁场的干扰，造成程序的跑飞，而陷入死循环。程序的正常运行被打断，由单片机控制的系统无法继续工作，会造成整个系统的陷入停滞状态，发生不可预料的后果。所以，出于对单片机运行状态进行实时监测的考虑，便产生了一种专门用于监测单片机程序运行状态的芯片，俗称"看门狗"(watchdog)。

-Constituted by the single-chip micro-computer system, often because the work of the microcontroller will be the interference from external electromagnetic field, causing the program to run to fly, and fall into an infinite loop. The normal operation of the program was interrupted by the SCM system can not continue to work, will cause the entire system to a standstill, the occurrence of unpredictable consequences. So, running out of single-chip real-time monitoring considerations, we have a program dedicated to monitoring the operational status of the microcontroller chip, commonly known as " watchdog"　(watchdog).