原创 ds18b20 c51源代码 作者[qlpic]（包含命令）

/*----------------------------------------------------
*   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);
}