mirror of
https://github.com/RobTillaart/Arduino.git
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170 lines
3.4 KiB
C++
170 lines
3.4 KiB
C++
//
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// FILE: DS18B20.cpp
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// AUTHOR: Rob.Tillaart@gmail.com
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// VERSION: 0.1.9
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// DATE: 2017-07-25
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// PUPROSE: library for DS18B20 temperature sensor with minimal footprint
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//
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// HISTORY:
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// 0.1.0 2017-07-25 initial version
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// 0.1.1 2020-02-18 added getAddress()
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// 0.1.2 2020-04-11 #pragma once, refactor
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// 0.1.3 2020-04-22 #1 fix library.json file
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// 0.1.4 2020-04-23 #2 add retry in begin() to support Wemos
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// 0.1.5 2020-04-29 #4 added set/getConfig + DEVICE_CRC_ERROR + example
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// 0.1.6 2020-06-07 fix library.json
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// 0.1.7 2020-12-20 add arduino CI + unit test
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// 0.1.8 2021-04-08 clear scratchpad before read + update readme.md
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// 0.1.9 2021-05-26 add oneWire.reset() in begin()
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#include "DS18B20.h"
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// OneWire commands
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#define STARTCONVO 0x44
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#define READSCRATCH 0xBE
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#define WRITESCRATCH 0x4E
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// Scratchpad locations
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#define TEMP_LSB 0
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#define TEMP_MSB 1
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#define HIGH_ALARM_TEMP 2
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#define LOW_ALARM_TEMP 3
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#define CONFIGURATION 4
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#define INTERNAL_BYTE 5
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#define COUNT_REMAIN 6
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#define COUNT_PER_C 7
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#define SCRATCHPAD_CRC 8
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// Device resolution
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#define TEMP_9_BIT 0x1F // 9 bit
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#define TEMP_10_BIT 0x3F // 10 bit
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#define TEMP_11_BIT 0x5F // 11 bit
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#define TEMP_12_BIT 0x7F // 12 bit
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DS18B20::DS18B20(OneWire* _oneWire)
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{
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_wire = _oneWire;
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_addresFound = false;
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_config = DS18B20_CLEAR;
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}
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bool DS18B20::begin(void)
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{
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_config = DS18B20_CLEAR;
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_addresFound = false;
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for (uint8_t retries = 3; (retries > 0) && (_addresFound == false); retries--)
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{
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_wire->reset();
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_wire->reset_search();
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_deviceAddress[0] = 0x00;
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_wire->search(_deviceAddress);
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_addresFound = _deviceAddress[0] != 0x00 &&
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_wire->crc8(_deviceAddress, 7) == _deviceAddress[7];
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}
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return _addresFound;
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}
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void DS18B20::readScratchPad(uint8_t *scratchPad, uint8_t fields)
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{
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_wire->reset();
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_wire->select(_deviceAddress);
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_wire->write(READSCRATCH);
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for (uint8_t i = 0; i < fields; i++)
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{
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scratchPad[i] = _wire->read();
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}
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_wire->reset();
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}
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bool DS18B20::isConversionComplete(void)
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{
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return (_wire->read_bit() == 1);
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}
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void DS18B20::requestTemperatures(void)
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{
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_wire->reset();
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_wire->skip();
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_wire->write(STARTCONVO, 0);
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}
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float DS18B20::getTempC(void)
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{
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ScratchPad scratchPad;
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for (int i = 0; i < 9; i++) scratchPad[i] = 0;
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if (_config & DS18B20_CRC)
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{
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readScratchPad(scratchPad, 9);
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if (_wire->crc8(scratchPad, 8) != scratchPad[SCRATCHPAD_CRC])
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{
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return DEVICE_CRC_ERROR;
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}
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}
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else
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{
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readScratchPad(scratchPad, 2);
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}
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int16_t rawTemperature = (((int16_t)scratchPad[TEMP_MSB]) << 8) | scratchPad[TEMP_LSB];
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float temp = 0.0625 * rawTemperature;
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if (temp < -55)
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{
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return DEVICE_DISCONNECTED;
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}
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return temp;
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}
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void DS18B20::setResolution(uint8_t newResolution)
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{
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_wire->reset();
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_wire->select(_deviceAddress);
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_wire->write(WRITESCRATCH);
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// two dummy values for LOW & HIGH ALARM
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_wire->write(0);
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_wire->write(100);
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switch (newResolution)
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{
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case 12:
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_wire->write(TEMP_12_BIT);
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break;
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case 11:
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_wire->write(TEMP_11_BIT);
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break;
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case 10:
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_wire->write(TEMP_10_BIT);
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break;
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case 9:
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default:
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_wire->write(TEMP_9_BIT);
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break;
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}
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_wire->reset();
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}
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bool DS18B20::getAddress(uint8_t* buf)
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{
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if (_addresFound)
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{
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for (uint8_t i = 0; i < 8; i++)
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{
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buf[i] = _deviceAddress[i];
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}
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}
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return _addresFound;
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}
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// -- END OF FILE --
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