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//---------------------------------------------------------------------------

// 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.

// ---------------------------------------------------------------------------

//

//  temp28.C - Module to read the DS18B20 - temperature measurement.

//

// ---------------------------------------------------------------------------

//

//

#include "ownet.h"

#include "temp28.h"

//----------------------------------------------------------------------

// Read the temperature of a DS18B20 (family code 0x28)

//

// 'portnum'     - number 0 to MAX_PORTNUM-1.  This number was provided to

//                 OpenCOM to indicate the port number.

// 'SerialNum'   - Serial Number of DS18B20 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 ReadTemperature28(int portnum, uchar *SerialNum, float *Temp)

{

   uchar rt=FALSE;

   uchar send_block[30],lastcrc8;

   int send_cnt, tsht, i, loop=0;

   int power;

   // set the device serial number to the counter device

   owSerialNum(portnum,SerialNum,FALSE);

   for (loop = 0; loop < 2; loop ++)

   {

      // check if the chip is connected to VDD

      if (owAccess(portnum))

      {

         owWriteByte(portnum,0xB4);

         power = owReadByte(portnum);

      }

      // access the device

      if (owAccess(portnum))

      {

         // send the convert command and if nesessary start power delivery

         if (power) {

            if (!owWriteBytePower(portnum,0x44))

               return FALSE;

         } else {

            if (!owWriteByte(portnum,0x44))

               return FALSE;

         }

         // sleep for 1 second

         msDelay(1000);

         // turn off the 1-Wire Net strong pull-up

         if (power) {

            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] << 8;

                  tsht = tsht | send_block[1];

                  if (tsht & 0x00001000)

                          tsht = tsht | 0xffff0000;

                  *Temp = ((float) tsht)/16;

                  // success

                  rt = TRUE;

                  break;

               }

            }

         }

      }

   }

   // return the result flag rt

   return rt;

}