Filipe Morais / Mbed 2 deprecated mini_project

Sensor with Web Server

Dependencies:   EthernetInterface mbed-rpc mbed-rtos mbed

DS18S20.cpp@0:c385e589a779, 2014-04-08 (annotated)

Committer:
afilipem
Date:
Tue Apr 08 12:13:32 2014 +0000
Revision:
0:c385e589a779
1 version;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
afilipem 0:c385e589a779 1 /*
afilipem 0:c385e589a779 2 * DS18S20. Maxim DS18S20 One-Wire Thermometer.
afilipem 0:c385e589a779 3 * Uses the OneWireCRC library.
afilipem 0:c385e589a779 4 *
afilipem 0:c385e589a779 5 * Copyright (C) <2010> Petras Saduikis <petras@petras.co.uk>
afilipem 0:c385e589a779 6 *
afilipem 0:c385e589a779 7 * This file is part of OneWireThermometer.
afilipem 0:c385e589a779 8 *
afilipem 0:c385e589a779 9 * OneWireThermometer is free software: you can redistribute it and/or modify
afilipem 0:c385e589a779 10 * it under the terms of the GNU General Public License as published by
afilipem 0:c385e589a779 11 * the Free Software Foundation, either version 3 of the License, or
afilipem 0:c385e589a779 12 * (at your option) any later version.
afilipem 0:c385e589a779 13 *
afilipem 0:c385e589a779 14 * OneWireThermometer is distributed in the hope that it will be useful,
afilipem 0:c385e589a779 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
afilipem 0:c385e589a779 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
afilipem 0:c385e589a779 17 * GNU General Public License for more details.
afilipem 0:c385e589a779 18 *
afilipem 0:c385e589a779 19 * You should have received a copy of the GNU General Public License
afilipem 0:c385e589a779 20 * along with OneWireThermometer. If not, see <http://www.gnu.org/licenses/>.
afilipem 0:c385e589a779 21 */
afilipem 0:c385e589a779 22
afilipem 0:c385e589a779 23 #include "DS18S20.h"
afilipem 0:c385e589a779 24 #include "DebugTrace.h"
afilipem 0:c385e589a779 25
afilipem 0:c385e589a779 26 DebugTrace pc_ds18S20(ON, TO_SERIAL);
afilipem 0:c385e589a779 27
afilipem 0:c385e589a779 28 DS18S20::DS18S20(bool crcOn, bool useAddr, bool parasitic, PinName pin) :
afilipem 0:c385e589a779 29 OneWireThermometer(crcOn, useAddr, parasitic, pin, DS18S20_ID)
afilipem 0:c385e589a779 30 {
afilipem 0:c385e589a779 31 }
afilipem 0:c385e589a779 32
afilipem 0:c385e589a779 33 float DS18S20::calculateTemperature(BYTE* data)
afilipem 0:c385e589a779 34 {
afilipem 0:c385e589a779 35 // DS18S20 basic resolution is always 9 bits, which can be enhanced as follows
afilipem 0:c385e589a779 36 bool signBit = false;
afilipem 0:c385e589a779 37 if (data[TEMPERATURE_MSB] & 0x80) signBit = true;
afilipem 0:c385e589a779 38
afilipem 0:c385e589a779 39 int read_temp = (data[TEMPERATURE_MSB] << 8) + data[TEMPERATURE_LSB];
afilipem 0:c385e589a779 40 if (signBit)
afilipem 0:c385e589a779 41 {
afilipem 0:c385e589a779 42 read_temp = (read_temp ^ 0xFFFF) + 1; // two's complement
afilipem 0:c385e589a779 43 read_temp *= -1;
afilipem 0:c385e589a779 44 }
afilipem 0:c385e589a779 45
afilipem 0:c385e589a779 46 float readTemp = (float)read_temp/2 ; // divide by 2
afilipem 0:c385e589a779 47 pc_ds18S20.traceOut("TEMP_READ: %f \r\n", readTemp); // 9 bit resolution value
afilipem 0:c385e589a779 48
afilipem 0:c385e589a779 49 // convert to real temperature
afilipem 0:c385e589a779 50 float tempCount = float(data[COUNT_PER_DEG_BYTE] - data[COUNT_REMAIN_BYTE])/(float)data[COUNT_PER_DEG_BYTE];
afilipem 0:c385e589a779 51 float realTemp = (readTemp - 0.25) + tempCount;
afilipem 0:c385e589a779 52 pc_ds18S20.traceOut("Temperature: %f \r\n", realTemp); // enhanced resolution value
afilipem 0:c385e589a779 53
afilipem 0:c385e589a779 54 return realTemp;
afilipem 0:c385e589a779 55 }