说明：  主函数void main()是程序的入口函数，单片机上电后先进行初始化，重置变量数值，然后对外围器件进行初始化，完后进入死循环不断的检测处理。如果没有进入死循环的话，那么程序就只执行一遍就退出了，而达不到实时检测的效果。
(The main function void main() is the entry function of the program. After the single-chip microcomputer is powered on, it initializes first, resets the value of the variable, and then initializes the peripheral devices. After that, it enters an endless loop of continuous detection processing. If it does not enter the infinite loop, then the program will only be executed once and then exit, and the effect of real-time detection will not be achieved.)