mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-09-20 00:55:58 -04:00
452 lines
8.3 KiB
C++
452 lines
8.3 KiB
C++
//
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// FILE: SGP30.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.2.0
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// DATE: 2021-06-24
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// PURPOSE: Arduino library for SGP30 environment sensor.
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// URL: https://github.com/RobTillaart/SGP30
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// https://www.adafruit.com/product/3709
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#include "SGP30.h"
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/////////////////////////////////////////////////////
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//
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// CONSTRUCTOR
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//
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SGP30::SGP30(TwoWire *wire)
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{
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_address = 0x58;
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_wire = wire;
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_tvoc = 0;
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_co2 = 0;
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_h2 = 0;
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_ethanol = 0;
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_lastTime = 0;
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_error = SGP30_OK;
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}
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#if defined (ESP8266) || defined(ESP32)
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bool SGP30::begin(uint8_t dataPin, uint8_t clockPin)
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{
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_wire = &Wire;
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if ((dataPin < 255) && (clockPin < 255))
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{
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_wire->begin(dataPin, clockPin);
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} else {
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_wire->begin();
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}
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if (! isConnected()) return false;
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return true;
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}
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#endif
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bool SGP30::begin()
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{
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_wire->begin();
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if (! isConnected()) return false;
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_init();
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return true;
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}
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bool SGP30::isConnected()
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{
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_wire->beginTransmission(_address);
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return ( _wire->endTransmission() == 0);
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}
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// INITIAL VERSION - needs optimization
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bool SGP30::getID()
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{
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_command(0x3682);
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delay(1);
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if (_wire->requestFrom(_address, (uint8_t)9) == 9)
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{
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for (uint8_t i = 0, j = 0; i < 3; i++)
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{
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_id[j++] = _wire->read();
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_id[j++] = _wire->read();
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uint8_t crc = _wire->read();
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uint16_t val = _id[j-2] * 256 + _id[j-1];
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if (_CRC8(val) != crc)
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{
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_error = SGP30_ERROR_CRC;
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return false;
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}
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}
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_error = SGP30_OK;
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return true;
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}
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_error = SGP30_ERROR_I2C;
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return false;
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}
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// expect to return 0x0022
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uint16_t SGP30::getFeatureSet()
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{
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_command(0x202F);
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delay(10);
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uint16_t rv = 0;
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if (_wire->requestFrom(_address, (uint8_t)3) == 3)
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{
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rv = _wire->read() << 8;
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rv += _wire->read();
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uint8_t crc = _wire->read();
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if (_CRC8(rv) != crc)
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{
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_error = SGP30_ERROR_CRC;
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return rv;
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}
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_error = SGP30_OK;
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return rv;
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}
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_error = SGP30_ERROR_I2C;
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return 0xFFFF;
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}
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// WARNING: resets all devices on I2C bus.
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void SGP30::GenericReset()
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{
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_command(0x0006);
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_init();
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};
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bool SGP30::measureTest()
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{
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uint16_t rv = 0;
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_command(0x2032);
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delay(220); // Page 11
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if (_wire->requestFrom(_address, (uint8_t)3) == 3)
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{
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rv = _wire->read() << 8;
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rv += _wire->read();
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uint8_t crc = _wire->read();
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if (_CRC8(rv) != crc)
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{
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_error = SGP30_ERROR_CRC;
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return false;
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}
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_error = SGP30_OK;
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return rv == 0xD400;
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}
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_error = SGP30_ERROR_I2C;
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return false;
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}
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/////////////////////////////////////////////////////
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//
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// MEASUREMENT
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//
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// SYNCHRONUOUS MODUS
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bool SGP30::measure(bool all) // this is the workhorse
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{
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// 1 second between measurements. Page 9
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if (millis() - _lastTime < 1000) return false;
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_lastTime = millis();
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request();
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delay(12); // blocking!!
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read();
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if (not all) return true;
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requestRaw();
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delay(25); // blocking!!
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readRaw();
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return true;
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}
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// A-SYNCHRONUOUS INTERFACE
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void SGP30::request()
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{
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_lastRequest = millis();
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_command(0x2008);
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}
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bool SGP30::read()
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{
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if (_lastRequest == 0) return false;
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if (millis() - _lastRequest < 13) return false; // Page 11
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_lastRequest = 0;
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if (_wire->requestFrom(_address, (uint8_t)6) != 6)
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{
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_error = SGP30_ERROR_I2C;
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return false;
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}
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_co2 = _wire->read() << 8;
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_co2 += _wire->read();
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uint8_t crc = _wire->read();
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if (_CRC8(_co2) != crc)
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{
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_error = SGP30_ERROR_CRC;
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return false;
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}
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_tvoc = _wire->read() << 8;
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_tvoc += _wire->read();
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crc = _wire->read();
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if (_CRC8(_tvoc) != crc)
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{
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_error = SGP30_ERROR_CRC;
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return false;
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}
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_error = SGP30_OK;
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return true;
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}
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void SGP30::requestRaw()
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{
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_lastRequest = millis();
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_command(0x2050);
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}
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bool SGP30::readRaw()
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{
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if (_lastRequest == 0) return false;
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if (millis() - _lastRequest < 26) return false; // Page 11
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_lastRequest = 0;
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if (_wire->requestFrom(_address, (uint8_t)6) != 6)
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{
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_error = SGP30_ERROR_I2C;
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return false;
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}
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_h2 = _wire->read() << 8;
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_h2 += _wire->read();
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uint8_t crc = _wire->read();
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if (_CRC8(_h2) != crc)
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{
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_error = SGP30_ERROR_CRC;
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return false;
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}
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_ethanol = _wire->read() << 8;
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_ethanol += _wire->read();
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crc = _wire->read();
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if (_CRC8(_ethanol) != crc)
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{
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_error = SGP30_ERROR_CRC;
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return false;
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}
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_error = SGP30_OK;
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return true;
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}
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// experimental - datasheet Page 2
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// 1.953125e-3 = 1/512
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float SGP30::getH2()
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{
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float cref = 0.5; // ppm
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return cref * exp((_srefH2 - _h2) * 1.953125e-3);
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}
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float SGP30::getEthanol()
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{
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float cref = 0.4; // ppm
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return cref * exp((_srefEth - _ethanol) * 1.953125e-3);
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}
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/////////////////////////////////////////////////////
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//
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// CALIBRATION
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//
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// slightly different formula
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// https://carnotcycle.wordpress.com/2012/08/04/how-to-convert-relative-humidity-to-absolute-humidity/
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// Absolute Humidity (grams/m3) = 6.112 × e^[(17.67 × T)/(T+243.5)] × rh × 2.1674
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// (273.15+T)
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// T in °C
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// RH == RelativeHumidity
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float SGP30::setRelHumidity(float T, float RH) // Page 10
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{
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// page 10 datasheet
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// AH = AbsoluteHumidity
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// uint16_t AH = 216.7 * RH/100 * 6.117 * exp((17.62 * T)/(243.12 + T)) / (273.15 + T);
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float absoluteHumidity = (2.167 * 6.112) * RH;
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absoluteHumidity *= exp((17.62 * T)/(243.12 + T));
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absoluteHumidity /= (273.15 + T);
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setAbsHumidity(absoluteHumidity);
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return absoluteHumidity;
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}
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void SGP30::setAbsHumidity(float absoluteHumidity)
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{
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uint16_t AH = absoluteHumidity;
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uint8_t tmp = (absoluteHumidity - AH) * 256;
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AH = (AH << 8) | tmp;
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_command(0x2061, AH); // Page 11
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}
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void SGP30::setBaseline(uint16_t CO2, uint16_t TVOC)
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{
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_command(0x201E, TVOC, CO2);
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}
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bool SGP30::getBaseline(uint16_t *CO2, uint16_t *TVOC)
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{
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_command(0x2015);
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if (_wire->requestFrom(_address, (uint8_t)6) != 6)
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{
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_error = SGP30_ERROR_I2C;
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return false;
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}
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*CO2 = _wire->read() << 8;
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*CO2 += _wire->read();
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uint8_t crc = _wire->read();
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if (_CRC8(*CO2) != crc)
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{
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_error = SGP30_ERROR_CRC;
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return false;
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}
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*TVOC = _wire->read() << 8;
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*TVOC += _wire->read();
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crc = _wire->read();
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if (_CRC8(*TVOC) != crc)
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{
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_error = SGP30_ERROR_CRC;
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return false;
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}
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_error = SGP30_OK;
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return true;
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}
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void SGP30::setTVOCBaseline(uint16_t TVOC)
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{
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_command(0x2077, TVOC);
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}
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bool SGP30::getTVOCBaseline(uint16_t *TVOC)
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{
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_command(0x20B3);
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if (_wire->requestFrom(_address, (uint8_t)3) != 3)
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{
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_error = SGP30_ERROR_I2C;
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return false;
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}
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*TVOC = _wire->read() << 8;
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*TVOC += _wire->read();
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uint8_t crc = _wire->read();
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if (_CRC8(*TVOC) != crc)
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{
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_error = SGP30_ERROR_CRC;
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return false;
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}
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_error = SGP30_OK;
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return true;
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}
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/////////////////////////////////////////////////////
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//
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// MISCELLANEOUS
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//
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int SGP30::lastError()
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{
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int error = _error;
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_error = SGP30_OK;
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return error;
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}
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/////////////////////////////////////////////////////
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//
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// PRIVATE
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//
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int SGP30::_command(uint16_t cmd)
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{
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_wire->beginTransmission(_address);
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_wire->write(cmd >> 8);
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_wire->write(cmd & 0xFF);
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_error = _wire->endTransmission();
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return _error;
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}
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int SGP30::_command(uint16_t cmd, uint16_t v1)
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{
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_wire->beginTransmission(_address);
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_wire->write(cmd >> 8);
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_wire->write(cmd & 0xFF);
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_wire->write(v1 >> 8);
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_wire->write(v1 & 0xFF);
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_wire->write(_CRC8(v1));
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_error = _wire->endTransmission();
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return _error;
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}
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int SGP30::_command(uint16_t cmd, uint16_t v1, uint16_t v2)
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{
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_wire->beginTransmission(_address);
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_wire->write(cmd >> 8);
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_wire->write(cmd & 0xFF);
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_wire->write(v1 >> 8);
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_wire->write(v1 & 0xFF);
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_wire->write(_CRC8(v1));
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_wire->write(v2 >> 8);
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_wire->write(v2 & 0xFF);
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_wire->write(_CRC8(v2));
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_error = _wire->endTransmission();
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return _error;
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}
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// for sending command - CRC lib.
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// always 2 bytes
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uint8_t SGP30::_CRC8(uint16_t data)
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{
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uint8_t val[2];
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val[0] = data >> 8;
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val[1] = data & 0xFF;
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uint8_t crc = 0xFF; // start value
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for(uint8_t i = 0; i < 2; i++)
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{
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crc ^= val[i];
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for (uint8_t b = 8; b > 0; b--)
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{
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if (crc & 0x80)
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crc = (crc << 1) ^ 0x31; // polynomial
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else
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crc <<= 1;
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}
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}
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return crc;
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};
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void SGP30::_init()
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{
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_command(0x2003);
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};
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// -- END OF FILE --
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