Meadow.Foundation.Sensors.Atmospheric.Sgp40

Sgp40
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

Code Example

private 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));
}

private 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:

Sgp40	Meadow Pin
GND	GND
SCL	D08 (SCL)
SDA	D07 (SDA)
VCC	3V3

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

Type	Name	Description
Meadow.Units.RelativeHumidity	humidity	Humidity compensation
Meadow.Units.Temperature	temperature	Temperature 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