说明：  C8051F系列单片机串口通讯程序，串口编程--接收PC发来的字符串,回发字符串.发送期间中断控制LED灯闪烁
(C8051F series single-chip serial communication program, serial programming- PC sent to receive the string, back-fat string. Sent during the interruption of control blinking LED lights)