Filipe Morais / Mbed 2 deprecated mini_project

Sensor with Web Server

Dependencies:   EthernetInterface mbed-rpc mbed-rtos mbed

DS18B20.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 * DS18B20. Maxim DS18B20 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 "DS18B20.h"
afilipem 0:c385e589a779 24 #include "DebugTrace.h"
afilipem 0:c385e589a779 25
afilipem 0:c385e589a779 26 DebugTrace pc_ds18B20(ON, TO_SERIAL);
afilipem 0:c385e589a779 27
afilipem 0:c385e589a779 28 DS18B20::DS18B20(bool crcOn, bool useAddr, bool parasitic, PinName pin) :
afilipem 0:c385e589a779 29 OneWireThermometer(crcOn, useAddr, parasitic, pin, DS18B20_ID)
afilipem 0:c385e589a779 30 {
afilipem 0:c385e589a779 31 }
afilipem 0:c385e589a779 32
afilipem 0:c385e589a779 33
afilipem 0:c385e589a779 34 void DS18B20::setResolution(eResolution resln)
afilipem 0:c385e589a779 35 {
afilipem 0:c385e589a779 36 // as the write to the configuration register involves a write to the
afilipem 0:c385e589a779 37 // high and low alarm bytes, need to read these registers first
afilipem 0:c385e589a779 38 // and copy them back on the write
afilipem 0:c385e589a779 39
afilipem 0:c385e589a779 40 BYTE read_data[THERMOM_SCRATCHPAD_SIZE];
afilipem 0:c385e589a779 41 BYTE write_data[ALARM_CONFIG_SIZE];
afilipem 0:c385e589a779 42
afilipem 0:c385e589a779 43 if (readAndValidateData(read_data))
afilipem 0:c385e589a779 44 {
afilipem 0:c385e589a779 45 // copy alarm and config data to write data
afilipem 0:c385e589a779 46 for (int k = 2; k < 5; k++)
afilipem 0:c385e589a779 47 {
afilipem 0:c385e589a779 48 write_data[k - 2] = read_data[k];
afilipem 0:c385e589a779 49 }
afilipem 0:c385e589a779 50 int config = write_data[2];
afilipem 0:c385e589a779 51 config &= 0x9F;
afilipem 0:c385e589a779 52 config ^= (resln << 5);
afilipem 0:c385e589a779 53 write_data[2] = config;
afilipem 0:c385e589a779 54
afilipem 0:c385e589a779 55 resetAndAddress();
afilipem 0:c385e589a779 56 oneWire.writeByte(WRITESCRATCH);
afilipem 0:c385e589a779 57 for (int k = 0; k < 3; k++)
afilipem 0:c385e589a779 58 {
afilipem 0:c385e589a779 59 oneWire.writeByte(write_data[k]);
afilipem 0:c385e589a779 60 }
afilipem 0:c385e589a779 61
afilipem 0:c385e589a779 62 // remember it so we can use the correct delay in reading the temperature
afilipem 0:c385e589a779 63 // for parasitic power
afilipem 0:c385e589a779 64 resolution = resln;
afilipem 0:c385e589a779 65 }
afilipem 0:c385e589a779 66 }
afilipem 0:c385e589a779 67
afilipem 0:c385e589a779 68 float DS18B20::calculateTemperature(BYTE* data)
afilipem 0:c385e589a779 69 {
afilipem 0:c385e589a779 70 bool signBit = false;
afilipem 0:c385e589a779 71 if (data[TEMPERATURE_MSB] & 0x80) signBit = true;
afilipem 0:c385e589a779 72
afilipem 0:c385e589a779 73 int read_temp = (data[TEMPERATURE_MSB] << 8) + data[TEMPERATURE_LSB];
afilipem 0:c385e589a779 74 if (signBit)
afilipem 0:c385e589a779 75 {
afilipem 0:c385e589a779 76 read_temp = (read_temp ^ 0xFFFF) + 1; // two's complement
afilipem 0:c385e589a779 77 read_temp *= -1;
afilipem 0:c385e589a779 78 }
afilipem 0:c385e589a779 79
afilipem 0:c385e589a779 80 //***I have a question. If the data is read earlier why it sets the resolution again now?
afilipem 0:c385e589a779 81 int resolution = (data[CONFIG_REG_BYTE] & 0x60) >> 5; // mask off bits 6,5 and move to 1,0
afilipem 0:c385e589a779 82 switch (resolution)
afilipem 0:c385e589a779 83 {
afilipem 0:c385e589a779 84 case nineBit: // 0.5 deg C increments
afilipem 0:c385e589a779 85 read_temp &= 0xFFF8; // bits 2,1,0 are undefined
afilipem 0:c385e589a779 86 pc_ds18B20.traceOut("9 bit resolution ...\r\n");
afilipem 0:c385e589a779 87 break;
afilipem 0:c385e589a779 88 case tenBit: // 0.25 deg C increments
afilipem 0:c385e589a779 89 read_temp &= 0xFFFC; // bits 1,0 are undefined
afilipem 0:c385e589a779 90 pc_ds18B20.traceOut("10 bit resolution ...\r\n");
afilipem 0:c385e589a779 91 break;
afilipem 0:c385e589a779 92 case elevenBit: // 0.125 deg C increments
afilipem 0:c385e589a779 93 read_temp &= 0xFFFE; // bit 0 is undefined, ***bit 0 is 2^
afilipem 0:c385e589a779 94 pc_ds18B20.traceOut("11 bit resolution ...\r\n");
afilipem 0:c385e589a779 95 break;
afilipem 0:c385e589a779 96 case twelveBit: // 0.0625 deg C increments
afilipem 0:c385e589a779 97 pc_ds18B20.traceOut("12 bit resolution ...\r\n");
afilipem 0:c385e589a779 98 break;
afilipem 0:c385e589a779 99 }
afilipem 0:c385e589a779 100 float realTemp = (float)read_temp/16 ;
afilipem 0:c385e589a779 101
afilipem 0:c385e589a779 102 pc_ds18B20.traceOut("TEMP_READ/REAL TEMP: %f \r\n", realTemp);
afilipem 0:c385e589a779 103
afilipem 0:c385e589a779 104 return realTemp;
afilipem 0:c385e589a779 105 }