/*! \brief  Read the temperature from a DS1820 temperature sensor.
*
*  This function will start a conversion and read back the temperature
*  from a DS1820 temperature sensor.
*
*  \param  bus A bitmask of the bus where the DS1820 is located.
*  
*  \param  id  The 64 bit identifier of the DS1820.
*
*  \return The 16 bit signed temperature read from the DS1820.
*/
signed int DS1820_ReadTemperature(unsigned char bus, unsigned char * id)
{
    signed int temperature;
    
    // Reset, presence.
    if (!OWI_DetectPresence(bus))
    {
        return DS1820_ERROR; // Error
    }
    // Match the id found earlier.
    OWI_MatchRom(id, bus);
    // Send start conversion command.
    OWI_SendByte(DS1820_START_CONVERSION, bus);
            // Wait until conversion is finished.
    // Bus line is held low until conversion is finished.
    while (!OWI_ReadBit(bus))
    {
    
    }
    // Reset, presence.
    if(!OWI_DetectPresence(bus))
    {
        return -1000; // Error
    }
    // Match id again.
    OWI_MatchRom(id, bus);
    // Send READ SCRATCHPAD command.
    OWI_SendByte(DS1820_READ_SCRATCHPAD, bus);
    // Read only two first bytes (temperature low, temperature high)
    // and place them in the 16 bit temperature variable.
    temperature = OWI_ReceiveByte(bus);
    temperature |= (OWI_ReceiveByte(bus) << 8);
    
    return temperature;
}

/*! \brief  Read a bit from the bus(es). (Software only driver)
*
*  Generates the waveform for reception of a bit on the 1-Wire(R) bus(es).
*
*  \param  pins    A bitmask of the bus(es) to read from.
*
*  \return A bitmask of the buses where a '1' was read.
*/
unsigned char OWI_ReadBit(unsigned char pins)
{
    unsigned char intState;
    unsigned char bitsRead;
    
    // Disable interrupts.
    intState = __save_interrupt();
    __disable_interrupt();
    
    // Drive bus low and delay.
    OWI_PULL_BUS_LOW(pins);
    __delay_cycles(OWI_DELAY_A_STD_MODE);
    
    // Release bus and delay.
    OWI_RELEASE_BUS(pins);
    __delay_cycles(OWI_DELAY_E_STD_MODE);
    
    // Sample bus and delay.
    bitsRead = OWI_PIN & pins;
    __delay_cycles(OWI_DELAY_F_STD_MODE);
    
    // Restore interrupts.
    __restore_interrupt(intState);
    
    return bitsRead;
}