说明：  串口收发程序，把发送的数据接收后用P1口的LED灯以二进制的形式显示并且蜂鸣器发出提示音，再把接收的数据加1并发出。 使用sTC Isp软件界面上的串口助手，选择对应的串口号，设置波特率为9600，选择HEx模式发送和接收
(The serial port transceiver program, after receiving the sent data, uses the LED light of P1 port to display in binary form and the buzzer sends out the prompt tone, and then adds 1 to the received data and sends out. Use the serial port assistant on the STC ISP software interface, select the corresponding serial port number, set the baud rate to 9600, and select the hex mode to send and receive)