单片机和PC通信，单片机与PC之间互传字符，单片机接收到PC端所传的字符串，然后返回给PC端，如果PC端所接受和发送的一致，则显示正确字符串，错误则显示通信异常-SCM and PC communications between the microcontroller and PC characters to each other, the microcontroller receives the PC side preaching string, and then returned to th