CanAirIO multi sensors library

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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.

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
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 TESTING
BME680 i2c Auto STABLE

NOTE: DHT22 is supported but is not recommended


  • Unified variables for all sensors
  • Auto UART port selection (Hw, Sw, UART1, UART2, etc)
  • Multiple i2c reads and one UART sensor read support
  • Real time registry of sensors unit registered (see multivariable)
  • 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
  • Public access to main objects of each library (full methods access)
  • Get unit symbol and name and each sub-sensor
  • Get the main sensor detected. Two main groups: CO2 and PM
  • Basic debug mode support toggle in execution
  • Basic power saving management with sample time > 30s on SPS30

Full list of all sub libraries supported here

Quick implementation

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

Full implementation

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

/// sensors data callback
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()));

/// sensors error callback
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.setDebugMode(false);                    // [optional] debug mode to get detailed msgs
    sensors.detectI2COnly(true);                    // [optional] force to only i2c sensors
    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.Panasonic);             // Force UART detection to Panasonic sensor
    // sensors.init(sensors.Sensirion);             // Force UART detection to Sensirion sensor
    // sensors.init(sensors.Mhz19);                 // Force UART detection to Mhz14 or Mhz19 CO2 sensor
    // sensors.init(sensors.SDS011);                // Force UART detection to SDS011 sensor
    // sensors.init(sensors.CM1106);                // Force UART detection to CM1106 CO2 sensor
    // sensors.init(sensors.SENSEAIRS8);            // 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)
    // ...


void loop() {
    sensors.loop();  // read sensor data and showed it


On your serial monitor you should have something like that:

-->[SETUP] Detecting sensors..
-->[SETUP] Sensor configured: SENSIRION
-->[MAIN] PM1.0: 002 PM2.5: 004 PM10: 006
-->[MAIN] PM1.0: 002 PM2.5: 002 PM10: 002
-->[MAIN] PM1.0: 002 PM2.5: 002 PM10: 002

Multivariable demo

In this demo with two devices and multiple sensors, you can choose the possible sub sensors units:

CanAirIO multivariable demo

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]));

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 =========");

*  M A I N

void setup() {
    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 auto configuration demo

CanAirIO sensorlib auto configuration demo on Youtube


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:


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 **
M5COREINK 14 13  
TTGO TQ 18 13  
HELTEC 18 17  
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 if it isn’t autodected:

sensors.init(sensors.Auto,RX,TX); // custom RX, custom TX pines.

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.


Compiling and Installing

We recommended PlatformIO because is more easy than Arduino IDE. For this, 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 --target upload

Arduino IDE

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

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:


Compiling and Installing

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:

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)


Thanks to all collaborators and CanAirIO community for testing and reports.

For more details of this documentation please visit the repository.