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0.2.1 SGP30
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Rob Tillaart
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@ -6,6 +6,11 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
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and this project adheres to [Semantic Versioning](http://semver.org/).
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## [0.2.1] - 2023-09-25
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- add Wire1 support for ESP32
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- update readme.md
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## [0.2.0] - 2023-01-27
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- Fix setBaseline() ==> PR #11 (kudos to countrysidecowboy)
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- update GitHub actions
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@ -2,8 +2,11 @@
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/SGP30/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/SGP30/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/SGP30/issues)
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[](https://github.com/RobTillaart/SGP30/blob/master/LICENSE)
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[](https://github.com/RobTillaart/SGP30/releases)
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[](https://registry.platformio.org/libraries/robtillaart/SGP30)
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# SGP30
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@ -67,13 +70,20 @@ or switch the VCC as a sort of ChipSelect signal.
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- https://github.com/RobTillaart/TCA9548 (I2C 8 channel multiplexer)
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#### Links
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- https://www.adafruit.com/product/3709 - the sensor.
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- https://www.co2.earth/ - current outdoor CO2 level can be used for calibrating.
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- https://keelingcurve.ucsd.edu/ - historical outdoor CO2 level.
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## Interface
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```cpp
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#include "SGP30.h"
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```
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### Constructor
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#### Constructor
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- **SGP30(TwoWire \*wire = &Wire)** Constructor with optional the Wire interface as parameter.
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- **bool begin()** starts the I2C bus and returns true if the device address 0x58 is visible on the I2C bus.
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@ -82,14 +92,14 @@ or switch the VCC as a sort of ChipSelect signal.
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- **void GenericReset()** WARNING resets all I2C devices on the bus that support this call!
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### Meta
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#### Meta
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- **bool getID()** reads the sensor ID into 12 bytes. (needs rework).
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- **uint16_t getFeatureSet()** returns 0x0022, indicates that commands used in this library are supported.
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- **bool measureTest()** verify the chip is working.
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### Synchronous measurements
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#### Synchronous measurements
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- **uint32_t lastMeasurement()** timestamp in milliseconds of the last sync measurement made.
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This convenience function is useful to prevent reading the sensor too often.
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@ -99,7 +109,7 @@ Note the measurement is slow as there is an active blocking until the sensor is
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If the last measurement is less than a second ago, no measurement is made and the function returns false.
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### A-synchronous measurements
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#### A-synchronous measurements
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With the async interface, the user should control that reads are at least one second apart.
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The user should also take care not to mix up different requests. See examples.
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@ -112,7 +122,7 @@ CO2 and TVOC are read and updated. Otherwise false is returned.
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H2 and Ethanol are read and updated. Otherwise false is returned.
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### Get the data
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#### Get the data
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The library caches the last read values, and these are the functions to access them.
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@ -122,7 +132,7 @@ The library caches the last read values, and these are the functions to access t
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- **uint16_t getEthanol_raw()** gets the raw Ethanol. Units unknown.
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### Calibration
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#### Calibration
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Check the datasheet for operating range, figure 7.
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@ -133,7 +143,7 @@ The function returns the absolute humidity.
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Concentration is in gram per cubic meter (g/m3)
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### Baseline functions
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#### Baseline functions
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The baseline functions give the sensor a reference value.
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After running in a known condition e.g. outside in open air, one can get the baseline values as a sort of calibration.
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@ -145,6 +155,12 @@ This is because the baselines are based upon recent reads.
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- **bool getBaseline(uint16_t \*CO2, uint16_t \*TVOC)** retrieves the baseline values from the sensor.
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- **void setBaseline(uint16_t CO2, uint16_t TVOC)** sets the baseline values.
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Note the outdoor calibration CO2 level differs per day and one should check
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a local airport or weather station for a good reference.
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The University of San Diego keeps track of CO2 for a long time now.
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See - https://keelingcurve.ucsd.edu/
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For faster accurate results for the TVOC under bad air conditions, read **Inceptive Baseline for TVOC measurements**
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(not tested)
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@ -152,12 +168,12 @@ For faster accurate results for the TVOC under bad air conditions, read **Incept
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- **void setTVOCBaseline(uint16_t TVOC)** sets the TVOC start value.
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### Miscellaneous
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#### Miscellaneous
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- **int lastError()** returns last error. (needs rework)
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### Experimental H2 Ethanol
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#### Experimental H2 Ethanol
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use at own risk.
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@ -180,28 +196,23 @@ The used references are based upon
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- **uint16_t getSrefEthanol()** returns value set.
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## Operational
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See examples
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## Links
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https://www.adafruit.com/product/3709 - the sensor.
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## Future
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#### Must
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- improve documentation
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#### Should
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- test
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- different boards
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- different gasses / afmosphere if possible.
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- different gasses / atmosphere if possible.
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#### Could
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- redo **getID()**
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- make defines for the magic numbers (commands)
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- move code from .h to .cpp
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@ -213,6 +224,16 @@ The CRC checking + error handling (since 0.1.4) adds around 330 bytes PROGMEM on
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There might be a need for a minimal class that only reads CO2 and TVOC, no baselines etc.
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for the smallest platforms.
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#### Wont
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## Support
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If you appreciate my libraries, you can support the development and maintenance.
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Improve the quality of the libraries by providing issues and Pull Requests, or
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donate through PayPal or GitHub sponsors.
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Thank you,
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@ -1,7 +1,7 @@
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//
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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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// VERSION: 0.2.1
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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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@ -33,7 +33,6 @@ SGP30::SGP30(TwoWire *wire)
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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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@ -269,11 +268,6 @@ float SGP30::getEthanol()
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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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@ -281,7 +275,7 @@ float SGP30::setRelHumidity(float T, float RH) // Page 10
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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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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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@ -2,7 +2,7 @@
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//
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// FILE: SGP30.h
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// AUTHOR: Rob Tillaart
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// VERSION: 0.2.0
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// VERSION: 0.2.1
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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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@ -12,7 +12,7 @@
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#include "Arduino.h"
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#include "Wire.h"
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#define SGP30_LIB_VERSION (F("0.2.0"))
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#define SGP30_LIB_VERSION (F("0.2.1"))
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#define SGP30_OK 0x00
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#define SGP30_ERROR_CRC 0xFF
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@ -15,9 +15,9 @@
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"type": "git",
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"url": "https://github.com/RobTillaart/SGP30.git"
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},
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"version": "0.2.0",
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"version": "0.2.1",
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"license": "MIT",
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"frameworks": "arduino",
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"frameworks": "*",
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"platforms": "*",
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"headers": "SGP30.h"
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}
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@ -1,5 +1,5 @@
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name=SGP30
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version=0.2.0
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version=0.2.1
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author=Rob Tillaart <rob.tillaart@gmail.com>
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maintainer=Rob Tillaart <rob.tillaart@gmail.com>
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sentence=Arduino library for SGP30 environment sensor.
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