DS18B20
OneWireThermometer.cpp@0:a47e8ec71a4e, 2017-09-06 (annotated)
- Committer:
- jack__zen
- Date:
- Wed Sep 06 05:35:15 2017 +0000
- Revision:
- 0:a47e8ec71a4e
onewire
Who changed what in which revision?
User | Revision | Line number | New contents of line |
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jack__zen | 0:a47e8ec71a4e | 1 | /* |
jack__zen | 0:a47e8ec71a4e | 2 | * OneWireThermometer. Base class for Maxim One-Wire Thermometers. |
jack__zen | 0:a47e8ec71a4e | 3 | * Uses the OneWireCRC library. |
jack__zen | 0:a47e8ec71a4e | 4 | * |
jack__zen | 0:a47e8ec71a4e | 5 | * Copyright (C) <2010> Petras Saduikis <petras@petras.co.uk> |
jack__zen | 0:a47e8ec71a4e | 6 | * |
jack__zen | 0:a47e8ec71a4e | 7 | * This file is part of OneWireThermometer. |
jack__zen | 0:a47e8ec71a4e | 8 | * |
jack__zen | 0:a47e8ec71a4e | 9 | * OneWireThermometer is free software: you can redistribute it and/or modify |
jack__zen | 0:a47e8ec71a4e | 10 | * it under the terms of the GNU General Public License as published by |
jack__zen | 0:a47e8ec71a4e | 11 | * the Free Software Foundation, either version 3 of the License, or |
jack__zen | 0:a47e8ec71a4e | 12 | * (at your option) any later version. |
jack__zen | 0:a47e8ec71a4e | 13 | * |
jack__zen | 0:a47e8ec71a4e | 14 | * OneWireThermometer is distributed in the hope that it will be useful, |
jack__zen | 0:a47e8ec71a4e | 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
jack__zen | 0:a47e8ec71a4e | 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
jack__zen | 0:a47e8ec71a4e | 17 | * GNU General Public License for more details. |
jack__zen | 0:a47e8ec71a4e | 18 | * |
jack__zen | 0:a47e8ec71a4e | 19 | * You should have received a copy of the GNU General Public License |
jack__zen | 0:a47e8ec71a4e | 20 | * along with OneWireThermometer. If not, see <http://www.gnu.org/licenses/>. |
jack__zen | 0:a47e8ec71a4e | 21 | */ |
jack__zen | 0:a47e8ec71a4e | 22 | |
jack__zen | 0:a47e8ec71a4e | 23 | #include "OneWireThermometer.h" |
jack__zen | 0:a47e8ec71a4e | 24 | #include "OneWireDefs.h" |
jack__zen | 0:a47e8ec71a4e | 25 | #include "DebugTrace.h" |
jack__zen | 0:a47e8ec71a4e | 26 | |
jack__zen | 0:a47e8ec71a4e | 27 | DebugTrace pc(ON, TO_SERIAL); |
jack__zen | 0:a47e8ec71a4e | 28 | |
jack__zen | 0:a47e8ec71a4e | 29 | // constructor specifies standard speed for the 1-Wire comms |
jack__zen | 0:a47e8ec71a4e | 30 | OneWireThermometer::OneWireThermometer(bool crcOn, bool useAddr, bool parasitic, PinName pin, int device_id) : |
jack__zen | 0:a47e8ec71a4e | 31 | useCRC(crcOn), useAddress(useAddr), useParasiticPower(parasitic), |
jack__zen | 0:a47e8ec71a4e | 32 | oneWire(pin, STANDARD), deviceId(device_id), resolution(twelveBit) |
jack__zen | 0:a47e8ec71a4e | 33 | { |
jack__zen | 0:a47e8ec71a4e | 34 | // NOTE: the power-up resolution of a DS18B20 is 12 bits. The DS18S20's resolution is always |
jack__zen | 0:a47e8ec71a4e | 35 | // 9 bits + enhancement, but we treat the DS18S20 as fixed to 12 bits for calculating the |
jack__zen | 0:a47e8ec71a4e | 36 | // conversion time Tconv. |
jack__zen | 0:a47e8ec71a4e | 37 | } |
jack__zen | 0:a47e8ec71a4e | 38 | |
jack__zen | 0:a47e8ec71a4e | 39 | bool OneWireThermometer::initialize() |
jack__zen | 0:a47e8ec71a4e | 40 | { |
jack__zen | 0:a47e8ec71a4e | 41 | // get the device address for use in selectROM() when reading the temperature |
jack__zen | 0:a47e8ec71a4e | 42 | // - not really needed except for device validation if using skipROM() |
jack__zen | 0:a47e8ec71a4e | 43 | if (useAddress) |
jack__zen | 0:a47e8ec71a4e | 44 | { |
jack__zen | 0:a47e8ec71a4e | 45 | pc.traceOut("\r\n"); |
jack__zen | 0:a47e8ec71a4e | 46 | pc.traceOut("New Scan\r\n"); |
jack__zen | 0:a47e8ec71a4e | 47 | |
jack__zen | 0:a47e8ec71a4e | 48 | oneWire.resetSearch(); |
jack__zen | 0:a47e8ec71a4e | 49 | if (!oneWire.search(address)) // search for 1-wire device address |
jack__zen | 0:a47e8ec71a4e | 50 | { |
jack__zen | 0:a47e8ec71a4e | 51 | pc.traceOut("No more addresses.\r\n"); |
jack__zen | 0:a47e8ec71a4e | 52 | wait(2); |
jack__zen | 0:a47e8ec71a4e | 53 | return false; |
jack__zen | 0:a47e8ec71a4e | 54 | } |
jack__zen | 0:a47e8ec71a4e | 55 | |
jack__zen | 0:a47e8ec71a4e | 56 | pc.traceOut("Address = "); |
jack__zen | 0:a47e8ec71a4e | 57 | for (int i = 0; i < ADDRESS_SIZE; i++) |
jack__zen | 0:a47e8ec71a4e | 58 | { |
jack__zen | 0:a47e8ec71a4e | 59 | pc.traceOut("%x ", (int)address[i]); |
jack__zen | 0:a47e8ec71a4e | 60 | } |
jack__zen | 0:a47e8ec71a4e | 61 | pc.traceOut("\r\n"); |
jack__zen | 0:a47e8ec71a4e | 62 | |
jack__zen | 0:a47e8ec71a4e | 63 | if (OneWireCRC::crc8(address, ADDRESS_CRC_BYTE) != address[ADDRESS_CRC_BYTE]) // check address CRC is valid |
jack__zen | 0:a47e8ec71a4e | 64 | { |
jack__zen | 0:a47e8ec71a4e | 65 | pc.traceOut("CRC is not valid!\r\n"); |
jack__zen | 0:a47e8ec71a4e | 66 | wait(2); |
jack__zen | 0:a47e8ec71a4e | 67 | return false; |
jack__zen | 0:a47e8ec71a4e | 68 | } |
jack__zen | 0:a47e8ec71a4e | 69 | |
jack__zen | 0:a47e8ec71a4e | 70 | if (address[0] != deviceId) |
jack__zen | 0:a47e8ec71a4e | 71 | { |
jack__zen | 0:a47e8ec71a4e | 72 | // Make sure it is a one-wire thermometer device |
jack__zen | 0:a47e8ec71a4e | 73 | if (DS18B20_ID == deviceId) |
jack__zen | 0:a47e8ec71a4e | 74 | pc.traceOut("You need to use a DS1820 or DS18S20 for correct results.\r\n"); |
jack__zen | 0:a47e8ec71a4e | 75 | else if (DS18S20_ID == deviceId) |
jack__zen | 0:a47e8ec71a4e | 76 | pc.traceOut("You need to use a DS18B20 for correct results.\r\n"); |
jack__zen | 0:a47e8ec71a4e | 77 | else |
jack__zen | 0:a47e8ec71a4e | 78 | pc.traceOut("Device is not a DS18B20/DS1820/DS18S20 device.\r\n"); |
jack__zen | 0:a47e8ec71a4e | 79 | |
jack__zen | 0:a47e8ec71a4e | 80 | wait(2); |
jack__zen | 0:a47e8ec71a4e | 81 | return false; |
jack__zen | 0:a47e8ec71a4e | 82 | } |
jack__zen | 0:a47e8ec71a4e | 83 | else |
jack__zen | 0:a47e8ec71a4e | 84 | { |
jack__zen | 0:a47e8ec71a4e | 85 | if (DS18B20_ID == deviceId) pc.traceOut("DS18B20 present and correct.\r\n"); |
jack__zen | 0:a47e8ec71a4e | 86 | if (DS18S20_ID == deviceId) pc.traceOut("DS1820/DS18S20 present and correct.\r\n"); |
jack__zen | 0:a47e8ec71a4e | 87 | } |
jack__zen | 0:a47e8ec71a4e | 88 | } |
jack__zen | 0:a47e8ec71a4e | 89 | |
jack__zen | 0:a47e8ec71a4e | 90 | return true; |
jack__zen | 0:a47e8ec71a4e | 91 | } |
jack__zen | 0:a47e8ec71a4e | 92 | |
jack__zen | 0:a47e8ec71a4e | 93 | // NOTE ON USING SKIP ROM: ok to use before a Convert command to get all |
jack__zen | 0:a47e8ec71a4e | 94 | // devices on the bus to do simultaneous temperature conversions. BUT can |
jack__zen | 0:a47e8ec71a4e | 95 | // only use before a Read Scratchpad command if there is only one device on the |
jack__zen | 0:a47e8ec71a4e | 96 | // bus. For purpose of this library it is assumed there is only one device |
jack__zen | 0:a47e8ec71a4e | 97 | // on the bus. |
jack__zen | 0:a47e8ec71a4e | 98 | void OneWireThermometer::resetAndAddress() |
jack__zen | 0:a47e8ec71a4e | 99 | { |
jack__zen | 0:a47e8ec71a4e | 100 | oneWire.reset(); // reset device |
jack__zen | 0:a47e8ec71a4e | 101 | if (useAddress) |
jack__zen | 0:a47e8ec71a4e | 102 | { |
jack__zen | 0:a47e8ec71a4e | 103 | oneWire.matchROM(address); // select which device to talk to |
jack__zen | 0:a47e8ec71a4e | 104 | } |
jack__zen | 0:a47e8ec71a4e | 105 | else |
jack__zen | 0:a47e8ec71a4e | 106 | { |
jack__zen | 0:a47e8ec71a4e | 107 | oneWire.skipROM(); // broadcast |
jack__zen | 0:a47e8ec71a4e | 108 | } |
jack__zen | 0:a47e8ec71a4e | 109 | } |
jack__zen | 0:a47e8ec71a4e | 110 | |
jack__zen | 0:a47e8ec71a4e | 111 | bool OneWireThermometer::readAndValidateData(BYTE* data) |
jack__zen | 0:a47e8ec71a4e | 112 | { |
jack__zen | 0:a47e8ec71a4e | 113 | bool dataOk = true; |
jack__zen | 0:a47e8ec71a4e | 114 | |
jack__zen | 0:a47e8ec71a4e | 115 | resetAndAddress(); |
jack__zen | 0:a47e8ec71a4e | 116 | oneWire.writeByte(READSCRATCH); // read Scratchpad |
jack__zen | 0:a47e8ec71a4e | 117 | |
jack__zen | 0:a47e8ec71a4e | 118 | pc.traceOut("read = "); |
jack__zen | 0:a47e8ec71a4e | 119 | for (int i = 0; i < THERMOM_SCRATCHPAD_SIZE; i++) |
jack__zen | 0:a47e8ec71a4e | 120 | { |
jack__zen | 0:a47e8ec71a4e | 121 | // we need all bytes which includes CRC check byte |
jack__zen | 0:a47e8ec71a4e | 122 | data[i] = oneWire.readByte(); |
jack__zen | 0:a47e8ec71a4e | 123 | pc.traceOut("%x ", (int)data[i]); |
jack__zen | 0:a47e8ec71a4e | 124 | } |
jack__zen | 0:a47e8ec71a4e | 125 | pc.traceOut("\r\n"); |
jack__zen | 0:a47e8ec71a4e | 126 | |
jack__zen | 0:a47e8ec71a4e | 127 | // Check CRC is valid if you want to |
jack__zen | 0:a47e8ec71a4e | 128 | if (useCRC && !(OneWireCRC::crc8(data, THERMOM_CRC_BYTE) == data[THERMOM_CRC_BYTE])) |
jack__zen | 0:a47e8ec71a4e | 129 | { |
jack__zen | 0:a47e8ec71a4e | 130 | // CRC failed |
jack__zen | 0:a47e8ec71a4e | 131 | pc.traceOut("CRC FAILED... \r\n"); |
jack__zen | 0:a47e8ec71a4e | 132 | dataOk = false; |
jack__zen | 0:a47e8ec71a4e | 133 | } |
jack__zen | 0:a47e8ec71a4e | 134 | |
jack__zen | 0:a47e8ec71a4e | 135 | return dataOk; |
jack__zen | 0:a47e8ec71a4e | 136 | } |
jack__zen | 0:a47e8ec71a4e | 137 | |
jack__zen | 0:a47e8ec71a4e | 138 | float OneWireThermometer::readTemperature() |
jack__zen | 0:a47e8ec71a4e | 139 | { |
jack__zen | 0:a47e8ec71a4e | 140 | BYTE data[THERMOM_SCRATCHPAD_SIZE]; |
jack__zen | 0:a47e8ec71a4e | 141 | float realTemp = -999; |
jack__zen | 0:a47e8ec71a4e | 142 | |
jack__zen | 0:a47e8ec71a4e | 143 | resetAndAddress(); |
jack__zen | 0:a47e8ec71a4e | 144 | oneWire.writeByte(CONVERT); // issue Convert command |
jack__zen | 0:a47e8ec71a4e | 145 | |
jack__zen | 0:a47e8ec71a4e | 146 | if (useParasiticPower) |
jack__zen | 0:a47e8ec71a4e | 147 | { |
jack__zen | 0:a47e8ec71a4e | 148 | // wait while converting - Tconv (according to resolution of reading) |
jack__zen | 0:a47e8ec71a4e | 149 | wait_ms(CONVERSION_TIME[resolution]); |
jack__zen | 0:a47e8ec71a4e | 150 | } |
jack__zen | 0:a47e8ec71a4e | 151 | else |
jack__zen | 0:a47e8ec71a4e | 152 | { |
jack__zen | 0:a47e8ec71a4e | 153 | // TODO |
jack__zen | 0:a47e8ec71a4e | 154 | // after the Convert command, the device should respond by transmitting 0 |
jack__zen | 0:a47e8ec71a4e | 155 | // while the temperature conversion is in progress and 1 when the conversion is done |
jack__zen | 0:a47e8ec71a4e | 156 | // - as were are not checking this (TODO), we use Tconv, as we would do for |
jack__zen | 0:a47e8ec71a4e | 157 | // parasitic power |
jack__zen | 0:a47e8ec71a4e | 158 | wait_ms(CONVERSION_TIME[resolution]); |
jack__zen | 0:a47e8ec71a4e | 159 | } |
jack__zen | 0:a47e8ec71a4e | 160 | |
jack__zen | 0:a47e8ec71a4e | 161 | if (readAndValidateData(data)) // issue Read Scratchpad commmand and get data |
jack__zen | 0:a47e8ec71a4e | 162 | { |
jack__zen | 0:a47e8ec71a4e | 163 | realTemp = calculateTemperature(data); |
jack__zen | 0:a47e8ec71a4e | 164 | } |
jack__zen | 0:a47e8ec71a4e | 165 | |
jack__zen | 0:a47e8ec71a4e | 166 | return realTemp; |
jack__zen | 0:a47e8ec71a4e | 167 | } |