File content as of revision 1:dcf2f8359398:
//---------------------------------------------------------------------------
// 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 "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 ReadTemperature(int portnum, uchar *SerialNum, float *Temp)
{
uchar rt=FALSE;
uchar send_block[30],lastcrc8;
int send_cnt, tsht, i, loop=0;
float tmp,cr,cpc;
// set the device serial number to the counter device
owSerialNum(portnum,SerialNum,FALSE);
for (loop = 0; loop < 2; loop ++)
{
// 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[1]/2;
if (send_block[2] & 0x01)
tsht |= -128;
tmp = (float)(tsht);
cr = send_block[7];
cpc = send_block[8];
if (((cpc - cr) == 1) && (loop == 0))
continue;
if (cpc == 0)
return FALSE;
else
tmp = tmp - (float)0.25 + (cpc - cr)/cpc;
*Temp = tmp;
// success
rt = TRUE;
break;
}
}
}
}
}
// return the result flag rt
return rt;
}