说明：  采用软件方法来实现单片机的通用串口引脚来模拟UART。根据要求采用P1.0作为发送端（TXD）,P1.1做为数据接受端（RXD），并采用全双工通信模式。由于MAX232电平转换芯片除了做UART的几个引脚后，还剩余T2IN,T2OUT,R2IN,R2OUT.所以采用模仿UART的接法.每次通信，发送的数据加1，接收的数据加2.用51系列单片机。
(The use of software methods to achieve single-chip Universal Serial pin to simulate the UART. P1.0 adopted in accordance with the requirements as the sending end (TXD), P1.1 as the receiving end the data (RXD), and the use of full-duplex communication mode. Since the MAX232 level translator chip UART to do apart from some of the pin, the remaining T2IN, T2OUT, R2IN, R2OUT. So used to imitate the UART connection. Each communication, to send data add one, add 2 to receive data. 51 Series single-chip microcomputer used.)