说明：  对GSM模块收发短信是采用到的AT指令进行详细说明，可以说是用AT指令进行收发短信的程序思路流程。按照这个思路可以在串口调试助手上进行测试。对正在写短信收发的各位有很大帮助
(GSM module to send and receive SMS using AT commands to carry out a detailed description, it can be said for using AT commands to send and receive text messages thinking process procedures. According to this line of thought can aide in debugging on serial testing. Writing to you to send and receive text messages are very helpful)