51 MCU serial communication uses interrupt mode

/*-------------------------------------------------  

Function: Connect the serial port to the computer, download the program, turn on the power  

        Open the serial port debugging assistant and set the baud rate to 2400 with no parity check.  

        The crystal oscillator is 12MHz, and the format used for sending and receiving is the same.  

        Character format, after setting correctly, the acceptance box can display:  

        The UART test, please enter the information in the send area  

----------------------------------------*/  

#include //Include the header file. Generally, no modification is required. The header file contains the definition of special function registers.                          

/*------------------------------------------------  

                   Function declaration  

----------------------------------------*/  

void SendStr(unsigned char *s);  

/*------------------------------------------------  

                    Serial port initialization  

----------------------------------------*/  

void InitUART (void)  

{  

    SCON = 0x50; // SCON: Mode 1, 8-bit UART, receive enabled    

    TMOD |= 0x20; // TMOD: timer 1, mode 2, 8-bit reinstall  

    //TH1 = 0xF3; // TH1: reload value 2400    

        TH1=0xfd;  

      TL1=0xfd; //11.0592MHZ crystal oscillator 9600 baud rate corresponding to the initial value  

    TR1 = 1; // TR1: timer 1 is turned on                           

    EA = 1; // Enable general interrupt  

   // ES = 1; // Enable serial port interrupt  

}                              

/*------------------------------------------------  

                    Main function  

----------------------------------------*/  

void main (void)  

{  

InitUART();  

SendStr("The UART test, please enter information in the send area");  

ES = 1; //Open serial port interrupt  

while (1)                         

    {  

    }  

}  

/*------------------------------------------------  

                    Send a byte  

----------------------------------------*/  

void SendByte(unsigned char dat)  

{  

 SBUF = dat;  

 while(!TI);  

      TI = 0;  

}  

/*------------------------------------------------  

                    Send a string  

----------------------------------------*/  

void SendStr(unsigned char *s)  

{  

 while(*s!='\0')// \0 indicates the end of the string, by checking whether the string ends  

  {  

  SendByte(*s);  

  s++;  

  }  

}  

/*------------------------------------------------  

                     Serial port interrupt program  

----------------------------------------*/  

void UART_SER (void) interrupt 4 //Serial interrupt service routine  

{  

    unsigned char Temp; //define temporary variable   

   if(RI) //Judge whether a receive interrupt is generated  

     {  

      RI=0; // Flag cleared  

      Temp=SBUF; //Read the value in the buffer  

      P1=Temp; //Output the value to port P1 for observation  

      SBUF=Temp; //Send the received value back to the computer  

     }  

   if(TI) //If it is a send flag, clear it  

     TI=0;  

}