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Meadow.Foundation.Sensors.Atmospheric.Sgp40

Sgp40
StatusStatus badge: working
Source codeGitHub
Datasheet(s)GitHub
NuGet packageNuGet Gallery for Meadow.Foundation.Sensors.Atmospheric.Sgp40

Code Example

Sgp40? sensor;

public override Task Initialize()
{
Resolver.Log.Info("Initializing...");

sensor = new Sgp40(Device.CreateI2cBus());

Resolver.Log.Info($"Sensor SN: {sensor.SerialNumber:x6}");

if (sensor.RunSelfTest())
{
Resolver.Log.Info("Self test successful");
}
else
{
Resolver.Log.Warn("Self test failed");
}

var consumer = Sgp40.CreateObserver(
handler: result =>
{
Resolver.Log.Info($"Observer: VOC changed by threshold; new index: {result.New}");
},
filter: result =>
{
return Math.Abs(result.New - result.Old ?? 0) > 10;
}
);
sensor.Subscribe(consumer);

sensor.Updated += (sender, result) =>
{
Resolver.Log.Info($" VOC: {result.New}");
};

return base.Initialize();
}

public override async Task Run()
{
await ReadConditions();

sensor?.StartUpdating(TimeSpan.FromSeconds(1));
}

async Task ReadConditions()
{
if (sensor == null) { return; }

var result = await sensor.Read();
Resolver.Log.Info("Initial Readings:");
Resolver.Log.Info($" Temperature: {result}");
}

Sample project(s) available on GitHub

Wiring Example

To wire a Sgp40 to your Meadow board, connect the following:

Sgp40Meadow Pin
GNDGND
SCLD08 (SCL)
SDAD07 (SDA)
VCC3V3

Class Sgp40

Provides access to the Sensirion SGP40 VOC sensor

Assembly: Sgp40.dll
View Source
Declaration
public class Sgp40 : ByteCommsSensorBase<int>, IObservable<IChangeResult<int>>, ISamplingSensor<int>, ISensor<int>, ISensor, ISamplingSensor, IDisposable, II2cPeripheral

Inheritance: System.Object -> Meadow.Foundation.ObservableBase<UNIT>

Implements:
System.IObservable<Meadow.IChangeResult<System.Int32>>, Meadow.Peripherals.Sensors.ISamplingSensor<System.Int32>, Meadow.Peripherals.Sensors.ISensor<System.Int32>, Meadow.Peripherals.Sensors.ISensor, Meadow.Peripherals.Sensors.ISamplingSensor, System.IDisposable, Meadow.Hardware.II2cPeripheral

Properties

VocIndex

The VOC Index, from the last reading

View Source
Declaration
public int VocIndex { get; }

SerialNumber

Serial number of the device

View Source
Declaration
public ulong SerialNumber { get; }

DefaultI2cAddress

The default I2C address for the peripheral

View Source
Declaration
public byte DefaultI2cAddress { get; }

Methods

Initialize()

Initialize the sensor

View Source
Declaration
protected void Initialize()

RunSelfTest()

This command triggers the built-in self-test checking for integrity of both hotplate and MOX material

View Source
Declaration
public bool RunSelfTest()
Returns

System.Boolean: true on successful test, otherwise false### ReadSensor() Reads data from the sensor

View Source
Declaration
protected override Task<int> ReadSensor()
Returns

System.Threading.Tasks.Task<System.Int32>: The latest sensor reading### TurnHeaterOff() This command turns the hotplate off and stops the measurement. Subsequently, the sensor enters idle mode.

View Source
Declaration
public void TurnHeaterOff()

SetCompensationData(RelativeHumidity, Temperature)

Set the compensation data

View Source
Declaration
public void SetCompensationData(RelativeHumidity humidity, Temperature temperature)
Parameters
TypeNameDescription
Meadow.Units.RelativeHumidityhumidityHumidity compensation
Meadow.Units.TemperaturetemperatureTemperature compensation

ClearCompensationData()

Clear the compensation data

View Source
Declaration
public void ClearCompensationData()

Implements

  • System.IObservable<Meadow.IChangeResult<System.Int32>>
  • Meadow.Peripherals.Sensors.ISamplingSensor<System.Int32>
  • Meadow.Peripherals.Sensors.ISensor<System.Int32>
  • Meadow.Peripherals.Sensors.ISensor
  • Meadow.Peripherals.Sensors.ISamplingSensor
  • System.IDisposable
  • Meadow.Hardware.II2cPeripheral