#include "reg51.h"
#include "INTRINS.H"
#include "LCD.h"

#define CLR_RI  (RI=0)
#define CLR_TI  (TI=0)
                               
unsigned char code ID[2][8]={ 0x28,0x1D,0x25,0x1D,0x00,0x00,0x00,0x80,
                              0x28,0x0e,0x9e,0x1c,0x00,0x00,0x00,0x32};
unsigned char currSensorNo=0;

sbit  TMDAT   =  P1^7;
sbit  RUN_LED =  P1^6;

/*------------------------------------------------
*
*------------------------------------------------*/
void serial_initial()
{
     TMOD=0X20;
     SCON=0X50;
     PCON=0X00;
     TL1=TH1=0XE8;
     TR1=1;
}

/*------------------------------------------------
*
*------------------------------------------------*/
void  send(unsigned char count,unsigned char SEND_Buf[])
{ 
unsigned char  i;
 for(i=0;i<count;i++)
 {
  SBUF=SEND_Buf;
  while(!TI);
  CLR_TI;
 }
}

/*----------------------------------------------------
*   delay N ms
*----------------------------------------------------*/
void Delay_ms (unsigned int Nms )
{
unsigned char i;
 while(Nms--)
 for(i=0; i<125; i++) ;
}

/*----------------------------------------------------
*   delay N count
*----------------------------------------------------*/
void Delay_Count (unsigned char Count )
{
    while(Count>0) Count--;
}

/*----------------------------------------------------
*   start Reset Pulse
----------------------------------------------------*/
void tmreset(void)
{
    TMDAT=0;
    Delay_Count(103);

    TMDAT=1;
     Delay_Count(4);
}

/*----------------------------------------------------
*        ACK
*----------------------------------------------------*/
void tmpre(void)
{
    while(TMDAT);
    while(~TMDAT);
    Delay_Count(4);
}

/*----------------------------------------------------
*   Read a bit from 1820
*----------------------------------------------------*/
bit tmrbit(void)
{
    int i=0;
    bit dat;
    TMDAT=0;i++;
        TMDAT=1;i++;i++;
    dat = TMDAT;
        Delay_Count(8);
    return dat;
}

/*----------------------------------------------------
*   Read a byte from 1820
*----------------------------------------------------*/
unsigned char tmrbyte(void)
{
unsigned char i,j,dat=0;

    for(i=1;i<=8;i++)
    {
        j=tmrbit();
        dat=(j<<7)|(dat>>1);
    }
    return dat;
}

/*----------------------------------------------------
*   Read a byte from 1820
*----------------------------------------------------*/
void tmwbyte(unsigned char dat)
{
    signed char   i=0;
    unsigned char j;
    bit testb;

    for(j=1;j<=8;j++)
    {
        testb=dat & 0x01;
        dat = dat>>1;
        if(testb)
        {
            TMDAT=0;
            i++;i++;
            TMDAT=1;
             Delay_Count(8);
        }
        else
        {
            TMDAT=0;
             Delay_Count(8);
            TMDAT=1;
            i++;i++;
        }
    }
}

/*----------------------------------------------------
*   send convert command to  1820
*----------------------------------------------------*/
void tmstart(void)
{
unsigned char i;
 tmreset();
    tmpre();
    Delay_ms(1);
/*  tmwbyte(0xcc);*/
    tmwbyte(0x55);
    for(i=0;i<8;i++)
     tmwbyte(ID[currSensorNo]);
    tmwbyte(0x44);
}

 serial_initial();
 send(8,id);
    for(;;)
    {
  RUN_LED=!RUN_LED;
/*     Read_Id();*/
  TX_C =!TX_C ;
  currSensorNo=(currSensorNo==1)?0:1;
  Display_AllTemp();
      /*Change();*/
  send(6,Digit);
  Delay_ms(1000);
         _nop_();
   }
}
參考鏈接：http://www.picavr.com/news/2008-05/5301.htm