串口通信，实现单片机之间的通信

用串口调试助手软件通过串口向单片机发送数据。当发送的数据为1到8时，分别对应点亮相应的发光二极管。发送其他数据，蜂鸣器会响。-Serial communication, to achieve communication between the microcontroller to send data to the microcontroller through the serial port using serial debugging assistant software. When transmit data is 1-8, the respective corresponding light-emitting diodes. Send other data, the buzzer will sound.