File content as of revision 0:fb8b6da96a8b:

/*
* OneWireThermometer. Base class for Maxim One-Wire Thermometers. 
* Uses the OneWireCRC library.
*
* Copyright (C) <2010> Petras Saduikis <petras@petras.co.uk>
*
* This file is part of OneWireThermometer.
*
* OneWireThermometer is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* 
* OneWireThermometer is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with OneWireThermometer.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "OneWireThermometer.h"
#include "OneWireDefs.h"
#include "DebugTrace.h"

DebugTrace pc(OFF, TO_SERIAL);

// constructor specifies standard speed for the 1-Wire comms
// Used to have params for CRCon and useAddress, can't see why you wouldn't use CRC and you have to use address since there could be more than one.
OneWireThermometer::OneWireThermometer(PinName pin, int device_id) :
    oneWire(pin, STANDARD), deviceId(device_id), resolution(twelveBit)
{
    // NOTE: the power-up resolution of a DS18B20 is 12 bits. The DS18S20's resolution is always
    // 9 bits + enhancement, but we treat the DS18S20 as fixed to 12 bits for calculating the
    // conversion time Tconv.
    deviceCount = 0;
}

bool OneWireThermometer::initialize()
{
    // get all the device addresses for use in selectROM() when reading the temperature
    pc.traceOut("\r\n");
    pc.traceOut("New Scan\r\n");

    oneWire.resetSearch();    
    while (oneWire.search(address))   // search for 1-wire device address
    {
        pc.traceOut("Address = ");
        for (int i = 0; i < ADDRESS_SIZE; i++) 
        {
            pc.traceOut("%x ", (int)address[i]);
            devices[deviceCount][i] = address[i];
        }
        pc.traceOut("\r\n");
        deviceCount++;
    }
    
    if (OneWireCRC::crc8(address, ADDRESS_CRC_BYTE) != address[ADDRESS_CRC_BYTE])   // check address CRC is valid
    {
        pc.traceOut("CRC is not valid!\r\n");
        wait(2);
        return false;
    }

    if (address[0] != deviceId)
    {                    
        // Make sure it is a one-wire thermometer device
        if (DS18B20_ID == deviceId)
            pc.traceOut("You need to use a DS1820 or DS18S20 for correct results.\r\n");
        else if (DS18S20_ID == deviceId)
            pc.traceOut("You need to use a DS18B20 for correct results.\r\n");
        else
          pc.traceOut("Device is not a DS18B20/DS1820/DS18S20 device.\r\n");
        
        wait(2);
        return false;   
    }
    else
    {
        if (DS18B20_ID == deviceId) pc.traceOut("DS18B20 present and correct.\r\n");
        if (DS18S20_ID == deviceId) pc.traceOut("DS1820/DS18S20 present and correct.\r\n");            
    }
    
    return true;
}

// NOTE ON USING SKIP ROM: ok to use before a Convert command to get all
// devices on the bus to do simultaneous temperature conversions. BUT can 
// only use before a Read Scratchpad command if there is only one device on the
// bus. For purpose of this library it is assumed there is only one device
// on the bus.
void OneWireThermometer::resetAndAddress()
{
    oneWire.reset();                // reset device 
    oneWire.matchROM(address);  // select which device to talk to
}

bool OneWireThermometer::readAndValidateData(BYTE* data)
{
    bool dataOk = true;
    
    resetAndAddress();
    oneWire.writeByte(READSCRATCH);    // read Scratchpad

    pc.traceOut("read = ");
    for (int i = 0; i < THERMOM_SCRATCHPAD_SIZE; i++) 
    {               
        // we need all bytes which includes CRC check byte
        data[i] = oneWire.readByte();
        pc.traceOut("%x ", (int)data[i]);
    }
    pc.traceOut("\r\n");

    // Check CRC is valid
    if (!(OneWireCRC::crc8(data, THERMOM_CRC_BYTE) == data[THERMOM_CRC_BYTE]))  
    {  
        // CRC failed
        pc.traceOut("CRC FAILED... \r\n");
        dataOk = false;
    }
    
    return dataOk;
}

float OneWireThermometer::readTemperature(int device)
{
    BYTE data[THERMOM_SCRATCHPAD_SIZE];
    float realTemp = -999;

    // need to select which device here.
    for (int i = 0; i < ADDRESS_SIZE; i++) 
    {
        address[i] = devices[device][i];
    }

    resetAndAddress();
    oneWire.writeByte(CONVERT);     // issue Convert command
    
    // Removed the check for parasitic power, since we waited the same time anyway.
    wait_ms(CONVERSION_TIME[resolution]);

    if (readAndValidateData(data))    // issue Read Scratchpad commmand and get data
    {
        realTemp = calculateTemperature(data);
    }
    
    return realTemp; 
}

int OneWireThermometer::getDeviceCount()
{
    return deviceCount;
}