Dallas DS18B20

bit tmpreadbit()
{
   unsigned int i;
   bit dat;
   DQ=0;i++;          //i++ for delay
   DQ=1;i++;i++;
   dat=DQ;
   i=8;
     while(i>0)i--;
   return (dat);
}

unsigned char read_byte()
{
    unsigned char i, value = 0;
    for (i=0;i<8;i++) {
        value >>= 1;
        if (read_bit()) value |= 0x80;
    }
    return value;
}

// Write a bit to the 1-Wire bus
void write_bit(unsigned char bitval)
{
    DQ = 0;                     // Pull DQ low
    _nop_(); _nop_(); // Wait 1-15 µs
    DQ = bitval;
    _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); // Wait rest of timeslot
    DQ = 1;          // Release the bus
}

// Write a byte to the 1-Wire bus
void write_byte(unsigned char val)
{
    unsigned char i;
    for (i=0; i<8; i++) {
        write_bit(val & 0x01); // LSB first
        val >>= 1;
    }
}