File content as of revision 0:1193dbfe28e2:

//---------------------------------------------------------------------------
// Copyright (C) 2000 Dallas Semiconductor Corporation, All Rights Reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY,  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL DALLAS SEMICONDUCTOR BE LIABLE FOR ANY CLAIM, DAMAGES
// OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
//
// Except as contained in this notice, the name of Dallas Semiconductor
// shall not be used except as stated in the Dallas Semiconductor
// Branding Policy.
// ---------------------------------------------------------------------------
//
//  temp10.C - Module to read the DS1920/DS1820 - temperature measurement.
//
//  Version: 2.00
//
// ---------------------------------------------------------------------------
//
//
#include "mbed.h"
#include "ownet.h"
#include "./Headers/readDS1920.h"

//----------------------------------------------------------------------
// Read the temperature of a DS1920/DS1820
//
// 'portnum'     - number 0 to MAX_PORTNUM-1.  This number was provided to
//                 OpenCOM to indicate the port number.
// 'SerialNum'   - Serial Number of DS1920/DS1820 to read temperature from
// 'Temp '       - pointer to variable where that temperature will be
//                 returned
//
// Returns: TRUE(1)  temperature has been read and verified
//          FALSE(0) could not read the temperature, perhaps device is not
//                   in contact
//

int ReadDS18B20(int portnum, uchar *SerialNum, float *Temp)
{
    uchar rt=FALSE;
    uchar send_block[30],lastcrc8;
    int send_cnt, tsht, i;
    float tmp;

    // set the device serial number to the counter device
    owSerialNum(portnum,SerialNum,FALSE);

    // access the device
    if (owAccess(portnum)) {
        // send the convert command and start power delivery
        if (!owWriteBytePower(portnum,0x44))
            return FALSE;

        // sleep for 1 second
        msDelay(1000);

        // turn off the 1-Wire Net strong pull-up
        if (owLevel(portnum,MODE_NORMAL) != MODE_NORMAL)
            return FALSE;

        // access the device
        if (owAccess(portnum)) {
            // create a block to send that reads the temperature
            // read scratchpad command
            send_cnt = 0;
            send_block[send_cnt++] = 0xBE;
            // now add the read bytes for data bytes and crc8
            for (i = 0; i < 9; i++)
                send_block[send_cnt++] = 0xFF;

            // now send the block
            if (owBlock(portnum,FALSE,send_block,send_cnt)) {
                // initialize the CRC8
                setcrc8(portnum,0);
                // perform the CRC8 on the last 8 bytes of packet
                for (i = send_cnt - 9; i < send_cnt; i++)
                    lastcrc8 = docrc8(portnum,send_block[i]);

                // verify CRC8 is correct
                if (lastcrc8 == 0x00) {
                    // calculate the high-res temperature
                    tsht = send_block[2]*256 + send_block[1];
                    tmp = (float)(tsht);
                    tmp = tmp / 16;
                    *Temp = tmp;
                    // success
                    rt = TRUE;
                }
            }
        }
    }
    // return the result flag rt
    return rt;
}