ARM监视串行口，将接收到的字符发送到字符再发送给串口，即按PC机键盘通过超级终端发送数据，开发板将接收到的数据再返还给PC，在超级终端上显示。-ARM monitors the serial port, the received characters are sent to a character and then sent to the serial port, ie the PC keyboard to send data via HyperTerminal, the board will