发一个51单片机的模拟串口代码

由于8位单片机一般只有一个串行接口，往往不够用，只能自己写一个模拟串口的程序，下面这个程序是自己早先写的，放上来，对别人也许有点用，注意接收端同时接到P3.2(INT0)

#include <at89X52.h>

#define DOUBLE_BAUDRATE

#define DATA_CORRUPT 0x80

#define BUFFER_OVERFLOW  0x81

#define F_OSC    11059200

#define BAUDRATE 9600 //115200//57600//19200//9600

#define BAUDRATE_CONST (256 – F_OSC/12/BAUDRATE)

#define HALF_BAUDRATE (256 – F_OSC/12/BAUDRATE/2)

#define DELAY_TIME 50;//ms

#define DELAY_CONST (DELAY_TIME/1000 * F_OSC)/12

#define DISABLE_RECEIVE() EX0 = 0;

#define ENABLE_RECEIVE() EX0 = 1;

#define RXD P1_2

#define TXD P1_3

char idata buffer[32] ;

unsigned char bdata DataBuf;

sbit DataBuf_0 = DataBuf ^ 0;

sbit DataBuf_1 = DataBuf ^ 1;

sbit DataBuf_2 = DataBuf ^ 2;

sbit DataBuf_3 = DataBuf ^ 3;

sbit DataBuf_4 = DataBuf ^ 4;

sbit DataBuf_5 = DataBuf ^ 5;

sbit DataBuf_6 = DataBuf ^ 6;

sbit DataBuf_7 = DataBuf ^ 7;

void send(char len,char * buf)

{

    char i,j;

    i=j=0;

    DISABLE_RECEIVE();

    TMOD |= 0x02;//MODE 3

    TL0 = BAUDRATE_CONST;//0x40;

    TH0 = BAUDRATE_CONST;//0x40;

    

    while(i<len)//for(i=0;i<len;i++)

    {

        DataBuf = buf[i];

        TL0 = BAUDRATE_CONST;

        TH0 = BAUDRATE_CONST;    

          TR0 = 1;

      TXD = 0;//send start bit

      //nop

      while(!TF0);

      TF0 = 0;

      TXD = DataBuf_0;//send bit 0

      while(!TF0);

      TF0 = 0;

      TXD = DataBuf_1;//send bit 1

      while(!TF0);

      TF0 = 0;

      TXD = DataBuf_2;//send bit 2

      while(!TF0);

      TF0 = 0;

      TXD = DataBuf_3;//send bit 3

      while(!TF0);

      TF0 = 0;

      TXD = DataBuf_4;//send bit 4

      while(!TF0);

      TF0 = 0;

      

      TXD = DataBuf_5;//send bit 5

      while(!TF0);

      TF0 = 0;

      

      TXD = DataBuf_6;//send bit 6

      while(!TF0);

      TF0 = 0;

      

      TXD = DataBuf_7;//send bit 7

      while(!TF0);

      TF0 = 0;

      

        TXD = 1;//send end bit 8

        while(!TF0);

        TF0 = 0;

        

        TR0 =0;//stop timer0

        i++;//next byte

    }

    ENABLE_RECEIVE();

}

unsigned char bdata DataBuf;

unsigned char LastError;

char recv_len;

void exint0_receive (void) interrupt 0 using 2  

{

    DISABLE_RECEIVE();

    TMOD |= 0x02;

    TL0 = HALF_BAUDRATE;

    TH0 = BAUDRATE_CONST;

        

    TR0 = 1; //start timer0

    

    while(!TF0); //delay 1/2 bit time to go to middle of start bit

    TF0 = 0;

    if(RXD == 1)

    {

        ENABLE_RECEIVE();

        return;

    }

    while(!TF0);//receive data bit 0

    TF0 = 0;

    DataBuf_0 = RXD;

    while(!TF0);//receive data bit 1

    TF0 = 0;

    DataBuf_1 = RXD;

    

    while(!TF0);//receive data bit 2

    TF0 = 0;

    DataBuf_2 = RXD;

    while(!TF0);//receive data bit 3

    TF0 = 0;

    DataBuf_3 = RXD;

    while(!TF0);//receive data bit 4

    TF0 = 0;

    DataBuf_4 = RXD;

    while(!TF0);//receive data bit 5

    TF0 = 0;

    DataBuf_5 = RXD;

    while(!TF0);//receive data bit 6

    TF0 = 0;

    DataBuf_6 = RXD;

    while(!TF0);//receive data bit 7

    TF0 = 0;

    DataBuf_7 = RXD;

    while(!TF0);//receive end bit

    TF0 = 0;

    

    if(RXD != 1)

    {

        LastError = 1;

        ENABLE_RECEIVE();

        return ;

    }

    TR0 = 0;//stop timer

     

    if(recv_len >=32)

    {

        LastError = BUFFER_OVERFLOW;

        ENABLE_RECEIVE();

        return;

                

    }

    buffer[recv_len++] = DataBuf;

    ENABLE_RECEIVE();

}

void InitSimuSerial()

{

    TMOD |= 0x02;

    TL0 = HALF_BAUDRATE; //wait at

    TH0 = BAUDRATE_CONST;

    

    IT0 = 1;

    EX0 = 1;

}

void main()

{

    P0 = 0xff;

    P1 = 0xff;

    P2 = 0xff;

    P3 = 0xff;

    InitSimuSerial();

    EA = 1;

    while(1)

    {

        if(recv_len >0)

        {

            send(recv_len,buffer);

            recv_len = 0;

        }

    }

}