Remarks

Ccs811
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

Code Example

Ccs811 sensor;

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

    var i2c = Device.CreateI2cBus(Meadow.Hardware.I2cBusSpeed.Fast);
    sensor = new Ccs811(i2c);

    var consumer = Ccs811.CreateObserver(
        handler: result =>
        {
            Resolver.Log.Info($"Observer triggered:");
            Resolver.Log.Info($"   new CO2: {result.New.Co2?.PartsPerMillion:N1}ppm, old: {result.Old?.Co2?.PartsPerMillion:N1}ppm.");
            Resolver.Log.Info($"   new VOC: {result.New.Voc?.PartsPerBillion:N1}ppb, old: {result.Old?.Voc?.PartsPerBillion:N1}ppb.");
        },
        filter: result =>
        {
            //c# 8 pattern match syntax. checks for !null and assigns var.
            if (result.Old is { } old)
            {
                return (
                (result.New.Co2.Value - old.Co2.Value).Abs().PartsPerMillion > 1000 // 1000ppm
                  &&
                (result.New.Voc.Value - old.Voc.Value).Abs().PartsPerBillion > 100 // 100ppb
                );
            }
            return false;
        }
    );
    sensor.Subscribe(consumer);

    sensor.Updated += (sender, result) =>
    {
        Resolver.Log.Info($"CO2: {result.New.Co2.Value.PartsPerMillion:n1}ppm, VOC: {result.New.Voc.Value.PartsPerBillion:n1}ppb");
    };

    return Task.CompletedTask;
}

public override async Task Run()
{
    var result = await sensor.Read();
    Resolver.Log.Info("Initial Readings:");
    Resolver.Log.Info($"  CO2: {result.Co2.Value.PartsPerMillion:n1}ppm");
    Resolver.Log.Info($"  VOC: {result.Voc.Value.PartsPerBillion:n1}ppb");

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

Sample project(s) available on GitHub

Wiring Example

To wire a Ccs811 to your Meadow board, connect the following:

Ccs811	Meadow Pin
GND	GND
VCC	3V3
SCL	D08
SDA	D07

It should look like the following diagram:

Characteristic	Locus
Inheritance	System.Object ObservableBase<System.ValueTuple<System.Nullable<Concentration>, System.Nullable<Concentration>>> SamplingSensorBase<System.ValueTuple<System.Nullable<Concentration>, System.Nullable<Concentration>>> PollingSensorBase<System.ValueTuple<System.Nullable<Concentration>, System.Nullable<Concentration>>> ByteCommsSensorBase<System.ValueTuple<System.Nullable<Concentration>, System.Nullable<Concentration>>> > Ccs811
Implements	ISamplingSensor<System.ValueTuple<System.Nullable<Concentration>, System.Nullable<Concentration>>> ISamplingSensor<System.ValueTuple<System.Nullable<Concentration>, System.Nullable<Concentration>>> IDisposable ICo2Sensor IVocSensor
Inherited Members	ByteCommsSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.Peripheral ByteCommsSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.ReadBuffer ByteCommsSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.WriteBuffer ByteCommsSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.Init(Int32, Int32) ByteCommsSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.Dispose(Boolean) ByteCommsSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.Dispose() PollingSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.StartUpdating(Nullable<TimeSpan>) PollingSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.StopUpdating() SamplingSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.samplingLock SamplingSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.Updated SamplingSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.SamplingTokenSource SamplingSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.Conditions SamplingSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.IsSampling SamplingSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.UpdateInterval SamplingSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.ReadSensor() SamplingSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.RaiseEventsAndNotify(IChangeResult<>) SamplingSensorBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.Read() ObservableBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.observers ObservableBase<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>.NotifyObservers(IChangeResult<>) Meadow.Foundation.ObservableBase<System.ValueTuple<System.Nullable<Concentration>, System.Nullable<Concentration>>>.Subscribe(IObserver<>) Meadow.Foundation.ObservableBase<System.ValueTuple<System.Nullable<Concentration>, System.Nullable<Concentration>>>.CreateObserver(Action<>, System.Nullable<Predicate<IChangeResult<UNIT>>>)
Namespace	Meadow.Foundation.Sensors.Atmospheric
Assembly	Ccs811.dll

Syntax

public class Ccs811 : ByteCommsSensorBase<(Concentration? Co2, Concentration? Voc)>, ISamplingSensor<(Concentration? Co2, Concentration? Voc)>, ISamplingSensor<(Concentration? Co2, Concentration? Voc)>, IDisposable, ICo2Sensor, IVocSensor

Constructors

Ccs811(II2cBus, Ccs811.Addresses)

Create a new Ccs811 object

Declaration

public Ccs811(II2cBus i2cBus, Ccs811.Addresses address = default(Ccs811.Addresses))

Parameters

Type	Name	Description
II2cBus	i2cBus	The I2C bus
Ccs811.Addresses	address	The I2C address

Ccs811(II2cBus, Byte)

Create a new Ccs811 object

Declaration

public Ccs811(II2cBus i2cBus, byte address)

Parameters

Type	Name	Description
II2cBus	i2cBus	The I2C bus
System.Byte	address	The I2C address

Properties

Co2

The measured CO2 concentration

Declaration

public Concentration? Co2 { get; }

Property Value

Type	Description
System.Nullable<Concentration>

Voc

The measured VOC concentration

Declaration

public Concentration? Voc { get; }

Property Value

Type	Description
System.Nullable<Concentration>

Methods

GetBaseline()

Get baseline value

Declaration

public ushort GetBaseline()

Returns

Type	Description
System.UInt16	The baseline value

GetMeasurementMode()

Get the current measurement mode

Declaration

public Ccs811.MeasurementMode GetMeasurementMode()

Returns

Type	Description
Ccs811.MeasurementMode	The measurement mode

Initialize()

Initialize the sensor

Declaration

protected void Initialize()

RaiseEventsAndNotify(IChangeResult<(Nullable<Concentration> Co2, Nullable<Concentration> Voc)>)

Raise events for subcribers and notify of value changes

Declaration

protected override void RaiseEventsAndNotify(IChangeResult<(Concentration? Co2, Concentration? Voc)> changeResult)

Parameters

Type	Name	Description
IChangeResult<System.ValueTuple<System.Nullable<Concentration>, System.Nullable<Concentration>>>	changeResult	The updated sensor data

ReadSensor()

Reads data from the sensor

Declaration

protected override Task<(Concentration? Co2, Concentration? Voc)> ReadSensor()

Returns

Type	Description
Task<System.ValueTuple<System.Nullable<Concentration>, System.Nullable<Concentration>>>	The latest sensor reading

Overrides

Meadow.Foundation.SamplingSensorBase<System.ValueTuple<System.Nullable<Concentration>, System.Nullable<Concentration>>>.ReadSensor()

SetBaseline(UInt16)

Set the baseline value

Declaration

public void SetBaseline(ushort value)

Parameters

Type	Name	Description
System.UInt16	value	The new baseline

SetMeasurementMode(Ccs811.MeasurementMode)

Set the Measurement mode

Declaration

public void SetMeasurementMode(Ccs811.MeasurementMode mode)

Parameters

Type	Name	Description
Ccs811.MeasurementMode	mode	The new mode

Events

Co2Updated

Event raised when the CO2 concentration value changes

Declaration

public event EventHandler<ChangeResult<Concentration>> Co2Updated

Event Type

Type	Description
EventHandler<ChangeResult<Concentration>>

VocUpdated

Event raised when the VOC concentration value changes

Declaration

public event EventHandler<ChangeResult<Concentration>> VocUpdated

Event Type

Type	Description
EventHandler<ChangeResult<Concentration>>