说明：  单片机的同步/异步通信，包括发送部分程序、接收部分程序、主控制程序，针对不同单片机，有着极高的学习意义
(Single-chip synchronous/asynchronous communication, including sending some of the procedures, to receive some of the procedures, the main control program, for different single-chip, has a very high significance of the study)