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Air Quality Sensors Library

Generic sensor manager, abstractions and bindings of multiple sensors libraries: Honeywell, Plantower, Panasonic, Sensirion, etc. and CO2 sensors. Also it's handling others environment sensors. This library is for general purpose, but also is the sensors library base of CanAirIO project.

For developers also you can check the complete library documentation here

Don't forget to star ⭐ this repository

Supported sensors

PM sensors

Sensor model	UART	I2C	Detection mode	Status
Honeywell HPMA115S0	Yes	—	Auto	DEPRECATED
Panasonic SN-GCJA5L	Yes	Yes	Auto	STABLE
Plantower models	Yes	—	Auto	STABLE
Nova SDS011	Yes	—	Auto	STABLE
IKEA Vindriktning	Yes	—	Select	STABLE
Sensirion SPS30	Yes	Yes	Select / Auto	STABLE

NOTE:
Panasonic via UART in ESP8266 maybe needs select in detection.

CO2 sensors

Sensor model	UART	I2C	Detection mode	Status
Sensirion SCD30	—	Yes	Auto	STABLE
Sensirion SCD4x	—	Yes	Auto	TESTING
MHZ19	Yes	—	Select	STABLE
CM1106	Yes	—	Select	STABLE
SenseAir S8	Yes	—	Select	STABLE

Environmental sensors

Sensor model	Protocol	Detection mode	Status
AM2320	i2c	Auto	STABLE
SHT31	i2c	Auto	STABLE
AHT10	i2c	Auto	STABLE
BME280	i2c	Auto	STABLE
BMP280	i2c	Auto	STABLE
BME680	i2c	Auto	STABLE
DfRobot SEN0469 NH3	i2c	Auto	TESTING
DFRobot SEN0466 CO	i2c	Auto	TESTING
DFRobot SEN0471 NO2	i2c	Auto	TESTING
Geiger CAJOE	GPIO	Select	TESTING
DHTxx	TwoWire	Select	DISABLED

NOTE:
DHT22 is supported but is not recommended. Please see the documentation.

Platforms supported

Platform	Variants	Notes	Status
ESP32	WROVER*	ESP32Devkit and similar (recommended)	STABLE
ESP32S3	LilyGo TDisplay	In testing	STABLE
ESP32C3	Devkit v3	In testing	STABLE
ESP8266	12	D1MINI tested and similar (old)	STABLE
Atmelsam	seeed_wio_terminal	Only works via i2c on left port	STABLE
Arduino	Atmel	Some third party libraries fails	IN PROGRESS

Features

Unified variables and getters for all sensors
Auto UART port selection (Hw, Sw, UART1, UART2, etc)
Multiple i2c sensors and one UART sensor supported at the same time
Two I2C channel supported (Wire and Wire1)
Real time registry of sensor units (see multivariable)
Get vendor names of all devices detected
Preselected main stream UART pins from popular boards
Auto config UART port for Plantower, Honeywell and Panasonic sensors
Unified calibration trigger for all CO2 sensors
Unified CO2 Altitude compensation
Unified temperature offset for CO2 and environment sensors
Add support for Kelvin and Fahrenheit on environment and CO2 sensors
Public access to main objects of each library (full methods access)
Get unit symbol and name and each sub-sensor
Get the main group type: NONE, PM, CO2 and ENV.
Basic debug mode support toggle in execution

Full list of all sub libraries supported here

Quick implementation

sensors.setOnDataCallBack(&onSensorDataOk); // all data read callback

sensors.init(); // start all sensors and

Sensors::setOnDataCallBack

void setOnDataCallBack(voidCbFn cb)

Get sensor data.

Definition: Sensors.cpp:242

Sensors::init

void init(u_int pms_type=0, int pms_rx=PMS_RX, int pms_tx=PMS_TX)

All sensors init.

Definition: Sensors.cpp:108

Full implementation

You can review a full implementation on CanAirIO project firmware, but a little brief is the next:

void onSensorDataOk() {
    Serial.print("PM2.5: " + String(sensors.getPM25()));
    Serial.print(" CO2: "  + String(sensors.getCO2()));
    Serial.print(" CO2H: " + String(sensors.getCO2humi()));
    Serial.print(" CO2T: " + String(sensors.getCO2temp()));
    Serial.print(" H: "    + String(sensors.getHumidity()));
    Serial.println(" T: "  + String(sensors.getTemperature()));
}
 
void onSensorDataError(const char * msg){
    Serial.println("Sensor read error: "+String(msg));
}
 
void setup() {
 
    sensors.setOnDataCallBack(&onSensorDataOk);     // all data read callback
    sensors.setOnErrorCallBack(&onSensorDataError); // [optional] error callback
    sensors.setSampleTime(15);                      // [optional] sensors sample time (default 5s)
    sensors.setTempOffset(cfg.toffset);             // [optional] temperature compensation
    sensors.setCO2AltitudeOffset(cfg.altoffset);    // [optional] CO2 altitude compensation
    sensors.setSeaLevelPressure(1036.25);           // [optional] Set sea level pressure in hpa
    sensors.setDebugMode(false);                    // [optional] debug mode to get detailed msgs
    sensors.detectI2COnly(true);                    // [optional] force to only i2c sensors
    sensors.setTemperatureUnit(TEMPUNIT::KELVIN);   // comment it for Celsius or set Fahrenheit
    sensors.init();                                 // Auto detection to UART and i2c sensors
 
    // Alternatives only for UART sensors (TX/RX):
 
    // sensors.init(SENSORS::Auto);                 // Auto detection to UART sensors (Honeywell, Plantower, Panasonic)
    // sensors.init(SENSORS::SGCJA5);               // Force UART detection to Panasonic sensor
    // sensors.init(SENSORS::SSPS30);               // Force UART detection to Sensirion sensor
    // sensors.init(SENSORS::SMHZ19);               // Force UART detection to Mhz14 or Mhz19 CO2 sensor
    // sensors.init(SENSORS::SDS011);               // Force UART detection to SDS011 sensor
    // sensors.init(SENSORS::IKEAVK);               // Force UART detection to IKEA Vindriktning sensor
    // sensors.init(SENSORS::SCM1106);              // Force UART detection to CM1106 CO2 sensor
    // sensors.init(SENSORS::SAIRS8);               // Force UART detection to SenseAirS8 CO2 sensor
    // sensors.init(SENSORS::Auto,PMS_RX,PMS_TX);   // Auto detection on custom RX,TX
  
    // Also you can access to sub-library objects, and perform for example calls like next:
 
    // sensors.sps30.sleep()
    // sensors.bme.readPressure();
    // sensors.mhz19.getRange();
    // sensors.scd30.getTemperatureOffset();
    // sensors.aht10.readRawData();
    // sensors.s8.set_ABC_period(period)
    // ...
 
    delay(500);
}
 
void loop() {
    sensors.loop();  // read sensor data and showed it
}

Multivariable demo

In this demo on two different devices with multiple sensors, you can choose the possible sub sensors units or variables:

In this demo on a simple sketch you could have a dinamyc list of variables of multiple sensors brands:

Multivariable alternative implementation

The last version added new getters to have the current status of each unit of each sensor connected to the device in real time. Also you can retrieve the list of device names and other stuff:

For example:

#include <Arduino.h>
#include <Sensors.hpp>
 
void printSensorsDetected() {
    uint16_t sensors_count =  sensors.getSensorsRegisteredCount();
    uint16_t units_count   =  sensors.getUnitsRegisteredCount();
    Serial.println("-->[MAIN] Sensors detected count\t: " + String(sensors_count));
    Serial.println("-->[MAIN] Sensors units count  \t: "  + String(units_count));
    Serial.print(  "-->[MAIN] Sensors devices names\t: ");
    int i = 0;
    while (sensors.getSensorsRegistered()[i++] != 0) {
        Serial.print(sensors.getSensorName((SENSORS)sensors.getSensorsRegistered()[i - 1]));
        Serial.print(",");
    }
    Serial.println();
}
 
void printSensorsValues() {
    Serial.println("\n-->[MAIN] Preview sensor values:");
    UNIT unit = sensors.getNextUnit();
    while(unit != UNIT::NUNIT) {
        String uName = sensors.getUnitName(unit);
        float uValue = sensors.getUnitValue(unit);
        String uSymb = sensors.getUnitSymbol(unit);
        Serial.print("-->[MAIN] " + uName + ": " + String(uValue) + " " + uSymb);
        unit = sensors.getNextUnit();
    }
}
 
void onSensorDataOk() {
    Serial.println("======= E X A M P L E   T E S T =========");
    printSensorsDetected();
    printSensorsValues(); 
    Serial.println("=========================================");
}
 
/******************************************************************************
*  M A I N
******************************************************************************/
 
void setup() {
    Serial.begin(115200);
    delay(100);
    sensors.setSampleTime(5);                       // config sensors sample time interval
    sensors.setOnDataCallBack(&onSensorDataOk);     // all data read callback
    sensors.setDebugMode(true);                     // [optional] debug mode
    sensors.detectI2COnly(false);                   // disable force to only i2c sensors
    sensors.init();                                 // Auto detection to UART and i2c sensors
}
 
void loop() {
    sensors.loop();  // read sensor data and showed it
}

UART detection demo

CanAirIO sensorlib auto configuration demo on Youtube

Wiring

The current version of library supports 3 kinds of wiring connection, UART, i2c and TwoWire, in the main boards the library using the defaults pins of each board, but in some special cases the pins are:

UART

Predefined UART

The library has pre-defined some UART pin configs, these are selected on compiling time. Maybe you don't need change anything with your board, and maybe the nexts alternatives works for you:

Board model	TX	RX	Notes
ESP32GENERIC	1	3	ESP32 Pio defaults
TTGOT7 / ESP32DEVKIT / D1MINI / NODEFINED	16	17	CanAirIO devices **
TTGO_TDISPLAY	12	13
M5COREINK	14	13
TTGO TQ	18	13
HELTEC	18	17
WEMOSOLED	15	13
ESP32PICOD4	3	1

** This pines are when you compile your project without specific any build variable or you board isn't in the list.

Custom UART

Also you could define a custom UART pins in the init() method and select specific sensors model, like this:

sensors.init(SENSORS::SDS011,yourRX,yourTX); // custom RX, custom TX pines.

I2C (recommended)

We are using the default pins for each board, some times it's pins are 21,22, please check your board schematic.

TwoWire (deprecated soon)

For now we are using it only for DHT sensors in PIN 23. For more info please review the next lines here.

Examples

PlatformIO (recommended)

We recommended PlatformIO because is more easy than Arduino IDE. For that, please install first PlatformIO and its command line tools (Windows, MacOs and Linux), pio command, then connect your compatible board to the USB and run the next command:

pio run -e esp32 --target upload

Also you can see some examples than have platformio.ini files for your project.

Arduino IDE

Only import the ino file of the sample and install the libraries listed on library.json and this library. Complete list of libraries used here

Arduino CLI

For run the examples, you first need to install arduino-cli or the Arduino IDE with the libraries referenced in lib_deps on the file platformio.ini, becuase Arduino don't install it automatically like PlatformIO. Then put CanAirIO sensor library in your library directory, you can download it from releases section.

Also you need to add the alternative links for supporting the ESP32 boards:

arduino-cli config init

in the .arduino15/arduino-cli.yaml file add:

board_manager:
  additional_urls:
    - https://arduino.esp8266.com/stable/package_esp8266com_index.json
    - https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

From arduino-cli you can run the basic example in a ESP32 board following these steps:

arduino-cli core update-index
arduino-cli core install esp32:esp32:lolin32
arduino-cli compile --fqbn esp32:esp32:lolin32 basic
arduino-cli upload --fqbn esp32:esp32:lolin32:UploadSpeed=115200 -p /dev/ttyUSB0 basic

where basic is the basic example on examples directory.

Supporting the project

If you want to contribute to the code or documentation, consider posting a bug report, feature request or a pull request.

When creating a pull request, we recommend that you do the following:

Clone the repository
Create a new branch for your fix or feature. For example, git checkout -b fix/my-fix or git checkout -b feat/my-feature.
Run to any clang formatter if it is a code, for example using the vscode formatter. We are using Google style. More info here
Document the PR description or code will be great
Target your pull request to be merged with devel branch

Also you can make a donation, be a patreon or buy a device:

Via Ethereum: 0x1779cD3b85b6D8Cf1A5886B2CF5C53a0E072C108
Via Liberapay: CanAirIO in LiberaPay
Buy a device: CanAirIO Bike in Tindie
Inviting us a coffee

TODO

[x] Auto detection for UART sensors (Honeywell, Panasonic and Plantower)
[x] Added SPS30 library with auto UART detection
[x] Disable/enable logs (debug mode flag)
[x] Added bme280, bmp280, aht10, sht31, am2320 i2c sensors
[x] Exposed public sub-libraries objects, sps30, aht10, etc.
[x] Added old DHT sensors
[x] Added CO2 sensors: MHZ19, SCD30, CM1106 via UART
[x] Added SDS011 particle metter
[x] BME680 support
[x] Added Sensirion SPS30 and Panasonic SN-GCJA5 via i2c
[x] Enable/Disable UART detection for force only i2c
[x] Temperature and Altitude compensation
[x] SenseAir S8 via UART support
[x] Multivariable selection (getNextUnit(),getUnitName(),etc)
[x] Two I2C channel supported for M5Stack Devices (M5StickC tested)
[x] Added CO, NO2 and NH3 sensors
[x] Added Geiger sensor support
[ ] New IKEA VINDSTYRKA device support
[ ] Sea level setting for Pressure sensors and others
[ ] Support to second UART port

Projects using this Library

CanAirIO Device: ESP32 Air quality device for mobile and fixed stations. (PM2.5 and CO2)
Medidor de CO2: Un medidor de CO2 de alta calidad con pantalla en color. (CO2)
M5CoreInk Multi Sensor: Wall CO2, T, H, P, Alt, sensor with low consumption (30 days)

Credits

Thanks to all collaborators and CanAirIO community for testing and reports. Visit us on Telegram