说明：  usb转UART,基于C8051F310.使用串口调试工具发给单片机一个十六进制数,单片机收到后再将这个数发送给上位机.
(usb to UART, based on the C8051F310. the use of single-chip serial debugging tools distributed to a hexadecimal number, Microcontroller Receive this number later sent to the host computer.)