串口通讯发送接收实验。在电脑上用串口调试工具发送一个数字给单片机，单片机接收这个数字后，将这个数字加上0x10，然后发送给串口调试工具，并在窗口中显示出来，接着再发送一串字符串给电脑，也在窗口中显示出来。-Serial Communication test for sending and receiving data. Using the serial communication tool to send a number to the 51 MCU, after 51MCU received