Stephen McGarry / AirCon

A copy of very incomplete program for forum

Dependencies:   mbed SDFileSystem

OneWireThermometer.cpp@1:d1c29c7b7ab3, 2012-03-17 (annotated)

Committer:
roselea
Date:
Sat Mar 17 14:34:23 2012 +0000
Revision:
1:d1c29c7b7ab3
Parent:
0:bfcb5b67b1d6 

        

        
Who changed what in which revision?

        

            
                
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/*





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* OneWireThermometer. Base class for Maxim One-Wire Thermometers. 





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* Uses the OneWireCRC library.





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*





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* Copyright (C) <2010> Petras Saduikis <petras@petras.co.uk>





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*





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* This file is part of OneWireThermometer.





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*





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* OneWireThermometer is free software: you can redistribute it and/or modify





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* it under the terms of the GNU General Public License as published by





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* the Free Software Foundation, either version 3 of the License, or





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* (at your option) any later version.





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* 





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* OneWireThermometer is distributed in the hope that it will be useful,





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* but WITHOUT ANY WARRANTY; without even the implied warranty of





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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the





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* GNU General Public License for more details.





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*





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* You should have received a copy of the GNU General Public License





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* along with OneWireThermometer.  If not, see <http://www.gnu.org/licenses/>.





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*/





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#include "OneWireThermometer.h"





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#include "OneWireDefs.h"





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#include "DebugTrace.h"





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DebugTrace pc(ON, TO_SERIAL);





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// constructor specifies standard speed for the 1-Wire comms





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OneWireThermometer::OneWireThermometer(bool crcOn, bool useAddr, bool parasitic, PinName pin, int device_id) :





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    useCRC(crcOn), useAddress(useAddr), useParasiticPower(parasitic), 





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    oneWire(pin, STANDARD), deviceId(device_id), resolution(twelveBit)





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{





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    // NOTE: the power-up resolution of a DS18B20 is 12 bits. The DS18S20's resolution is always





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    // 9 bits + enhancement, but we treat the DS18S20 as fixed to 12 bits for calculating the





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    // conversion time Tconv.





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}





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bool OneWireThermometer::initialize()





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{





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    // get the device address for use in selectROM() when reading the temperature





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    // - not really needed except for device validation if using skipROM()





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    if (useAddress)





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    {





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        pc.traceOut("\r\n");





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        pc.traceOut("New Scan\r\n");





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        oneWire.resetSearch();    





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        if (!oneWire.search(address))   // search for 1-wire device address





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        {            





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            pc.traceOut("No more addresses.\r\n");





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            wait(2);





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            return false;





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        }





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        pc.traceOut("Address = ");





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        for (int i = 0; i < ADDRESS_SIZE; i++) 





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        {





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            pc.traceOut("%.2X", (int)address[i]);





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        }





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        pc.traceOut("\r\n");





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        if (OneWireCRC::crc8(address, ADDRESS_CRC_BYTE) != address[ADDRESS_CRC_BYTE])   // check address CRC is valid





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        {





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            pc.traceOut("CRC is not valid!\r\n");





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            wait(2);





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            return false;





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        }





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        if (address[0] != deviceId)





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        {                    





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            // Make sure it is a one-wire thermometer device





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            if (DS18B20_ID == deviceId)





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                pc.traceOut("You need to use a DS1820 or DS18S20 for correct results.\r\n");





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            else if (DS18S20_ID == deviceId)





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                pc.traceOut("You need to use a DS18B20 for correct results.\r\n");





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            else





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              pc.traceOut("Device is not a DS18B20/DS1820/DS18S20 device.\r\n");





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            wait(2);





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            return false;   





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        }





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        else





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        {





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            if (DS18B20_ID == deviceId) pc.traceOut("DS18B20 present and correct.\r\n");





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            if (DS18S20_ID == deviceId) pc.traceOut("DS1820/DS18S20 present and correct.\r\n");            





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        }





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    }





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    return true;





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}





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// NOTE ON USING SKIP ROM: ok to use before a Convert command to get all





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// devices on the bus to do simultaneous temperature conversions. BUT can 





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// only use before a Read Scratchpad command if there is only one device on the





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// bus. For purpose of this library it is assumed there is only one device





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// on the bus.





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void OneWireThermometer::resetAndAddress()





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{





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    oneWire.reset();                // reset device 





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    if (useAddress)





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    {





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        oneWire.matchROM(address);  // select which device to talk to





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    }





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    else





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    {





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        oneWire.skipROM();          // broadcast





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    }





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}





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bool OneWireThermometer::readAndValidateData(BYTE* data)





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{





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    bool dataOk = true;





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    resetAndAddress();





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    oneWire.writeByte(READSCRATCH);    // read Scratchpad





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   // pc.traceOut("read = ");





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    for (int i = 0; i < THERMOM_SCRATCHPAD_SIZE; i++) 





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    {               





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        // we need all bytes which includes CRC check byte





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        data[i] = oneWire.readByte();





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        //pc.traceOut("%x ", (int)data[i]);





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    }





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   // pc.traceOut("\r\n");





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    // Check CRC is valid if you want to





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    if (useCRC && !(OneWireCRC::crc8(data, THERMOM_CRC_BYTE) == data[THERMOM_CRC_BYTE]))  





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    {  





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        // CRC failed





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        //pc.traceOut("CRC FAILED... \r\n");





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        dataOk = false;





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    }





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    return dataOk;





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}





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float OneWireThermometer::readTemperature()





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{





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    BYTE data[THERMOM_SCRATCHPAD_SIZE];





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    float realTemp = -999;





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    resetAndAddress();





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    oneWire.writeByte(CONVERT);     // issue Convert command





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    if (useParasiticPower)





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    {





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        // wait while converting - Tconv (according to resolution of reading)





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        wait_ms(CONVERSION_TIME[resolution]);





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    }





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    else





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    {





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        // TODO





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        // after the Convert command, the device should respond by transmitting 0





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        // while the temperature conversion is in progress and 1 when the conversion is done





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        // - as were are not checking this (TODO), we use Tconv, as we would do for





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        // parasitic power 





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        wait_ms(CONVERSION_TIME[resolution]);





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    }





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    if (readAndValidateData(data))    // issue Read Scratchpad commmand and get data





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    {





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        realTemp = calculateTemperature(data);





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    }





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    return realTemp; 





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}





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BYTE* OneWireThermometer::get_address()





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{





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    return address;





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}