说明：  1.通过PC端的串口调试工具，从PC端发出一个十六进制的数， 通过串口传输到单片机，并有单片机通过LED数码管显示其ASII码，而且单片机又将这个数发回PC端，并在PC端显示出来，从而实现单片机与PC机的通讯 2.可以实现对下位机数据实时采集（如温度,程序中设定的是37摄氏度） 3.可以控制流水灯或继电器开关等
(1. Through the PC-side debugging tools for serial port, from the PC client sends a hexadecimal number, by serial transmission to the microcontroller, and a single-chip through the LED digital tube display its ASII code, but also single-chip microcomputer this number back to PC client, and displayed in the client PC in order to achieve single-chip microcomputer and PC-communication 2. can be achieved for the next bit of real-time machine data collection (such as temperature, the procedures set is 37 degrees C) 3. flowing water can be controlled such as lights or relay switch)