Room Weather is an Arduino library that aims to provide plug and play support for monitoring air quality using STEMMA QT I2C sensors.

Supported sensors simply need to be plugged into the I2C bus of the Arduino to access their readings.

The hope is to provide a simple system for monitoring air quality in houses, workshops 3d printer enclosures etc. using off the shelf components and simple connectors.

This library will work with any Arduino board, but we specifically reccomend the Adafruit ESP32 Feather V2 since the integrated ESP32 WiFi enables additional features within this library and the integrated STEMMA QT connector allows for quick solderless connections to sensors.

• HTU31D Temp & Humidity
• SGP30 VOC & C02
• PMSA003I Air Quality

See examples folder for full usage examples.

In it's simplest form a Room Weather instance can be created simply by specifying a location.

RoomWeather *rw = new RoomWeather("office");

Alternatively, Room Weather can connect to WiFi which gives it the ability to export sensor data as Prometheus metrics.

char[] ssid = "your_ssid";
char[] password = "your_password";
RoomWeather *rw = new RoomWeather("office", ssid, password);

Calling Detect will trigger Room Weather to automatically detect any supported sensors connected on I2C.

rw->Detect();

Calling Read will trigger Room Weather to read the values of all detected sensors immediately.

rw->Read();

Alternatively, you can pass an interval in milliseconds to Read which will cause the sensors to be read to only if the time since the last read is greater than the given interval.

rw->Read(1000);

This means you can call Read in your main loop in a non blocking fashion knowing that sensors values are updated at the interval you specify, without bombarding the sensors with reads during every iteration of the loop.

Collected sensor values are available via the Values object.

rw->Values.Htu31d.Humidity

More information about utilizing and accessing sensor values can be found in the Sensor Utilization Section

Calling Print will print detected sensor data to the serial port. Print assumes that Serial.begin has already been called.

rw->Print();

Calling Print and passing an index will print the values of the specified sensor.

rw->Print(RW_SPG30_INDEX);

• RW_HTU31D_INDEX
• RW_SPG30_INDEX
• RW_PMSA003I_INDEX

Sensor data can automatically be exposed in Prometheus metric format on boards that have WiFi enabled.

RoomWeather *rw;

void setup() {
  rw = new RoomWeather("office", "wifi_ssid", "wifipassword");
  rw->Detect();
}

void loop() {
  rw->Read();

  // ServeMetrics will handle any incoming http request and respond with available sensor 
  // data in prometheus metric format
  rw->ServeMetrics();
}

rw->Values.Htu31d.Humidity;
rw->Values.Htu31d.AsboluteHumidity;
rw->Values.Htu31d.TemperatureCelsius;
rw->Values.Htu31d.TemperatureFahrenheit;

• Fahrenheit temperature is made available by converting the sensor's celsius reading.
• Absolute humitidy is made available by a a calculation using the sensor's humidity and temperature readings.

rw->Values.Sgp30.CO2;
rw->values.Sgp30.VOC;

• If HTU31D has been detected, it's absolute humidity value will be automatically provided to SGP30 for more accurate readings.

values->Pmsa003i.Pm10Standard;
values->Pmsa003i.Pm25Standard;
values->Pmsa003i.Pm100Standard;
values->Pmsa003i.Pm10Env;
values->Pmsa003i.Pm25Env;
values->Pmsa003i.Pm100Env;
values->Pmsa003i.Particles03um;
values->Pmsa003i.Particles05um;
values->Pmsa003i.Particles10um;
values->Pmsa003i.Particles25um;
values->Pmsa003i.Particles50um;
values->Pmsa003i.Particles100um;