Remarks

Max44009
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

The Max44009 is an analog ambient light sensor.

Code Example

Max44009 sensor;

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

    sensor = new Max44009(Device.CreateI2cBus());

    // Example that uses an IObservable subscription to only be notified when the filter is satisfied
    var consumer = Max44009.CreateObserver(
        handler: result => Resolver.Log.Info($"Observer: filter satisifed: {result.New.Lux:N2}Lux, old: {result.Old?.Lux:N2}Lux"),

        // only notify if the visible light changes by 100 lux (put your hand over the sensor to trigger)
        filter: result => {
            if (result.Old is { } old) { //c# 8 pattern match syntax. checks for !null and assigns var.
                // returns true if > 100lux change
                return (result.New - old).Abs().Lux > 100;
            }
            return false;
        });

    sensor.Subscribe(consumer);

    // classical .NET events can also be used:
    sensor.Updated += (sender, result) => Resolver.Log.Info($"Light: {result.New.Lux:N2}Lux");

    return Task.CompletedTask;
}

public override async Task Run()
{
    var result = await sensor.Read();
    Resolver.Log.Info("Initial Readings:");
    Resolver.Log.Info($" Light: {result.Lux:N2}Lux");

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

Sample project(s) available on GitHub

Wiring Example

To wire a Max44009 to your Meadow board, connect the following:

Max44009	Meadow Pin
SCL	D08
SDA	D07
GND	GND
VCC	3V3

It should look like the following diagram:

Characteristic	Locus
Inheritance	System.Object ObservableBase<Illuminance> SamplingSensorBase<Illuminance> PollingSensorBase<Illuminance> ByteCommsSensorBase<Illuminance> > Max44009
Implements	ISamplingSensor<Illuminance> ISamplingSensor<Illuminance> IDisposable
Inherited Members	ByteCommsSensorBase<Illuminance>.Peripheral ByteCommsSensorBase<Illuminance>.ReadBuffer ByteCommsSensorBase<Illuminance>.WriteBuffer ByteCommsSensorBase<Illuminance>.Init(Int32, Int32) ByteCommsSensorBase<Illuminance>.Dispose(Boolean) ByteCommsSensorBase<Illuminance>.Dispose() PollingSensorBase<Illuminance>.StartUpdating(Nullable<TimeSpan>) PollingSensorBase<Illuminance>.StopUpdating() SamplingSensorBase<Illuminance>.samplingLock SamplingSensorBase<Illuminance>.Updated SamplingSensorBase<Illuminance>.SamplingTokenSource SamplingSensorBase<Illuminance>.Conditions SamplingSensorBase<Illuminance>.IsSampling SamplingSensorBase<Illuminance>.UpdateInterval SamplingSensorBase<Illuminance>.RaiseEventsAndNotify(IChangeResult<>) SamplingSensorBase<Illuminance>.Read() ObservableBase<Illuminance>.observers ObservableBase<Illuminance>.NotifyObservers(IChangeResult<>) Meadow.Foundation.ObservableBase<Illuminance>.Subscribe(IObserver<>) Meadow.Foundation.ObservableBase<Illuminance>.CreateObserver(Action<>, System.Nullable<Predicate<IChangeResult<UNIT>>>)
Namespace	Meadow.Foundation.Sensors.Light
Assembly	Max44009.dll

Syntax

public class Max44009 : ByteCommsSensorBase<Illuminance>, ISamplingSensor<Illuminance>, ISamplingSensor<Illuminance>, IDisposable

Constructors

Max44009(II2cBus, Byte)

Create a new Max44009 object

Declaration

public Max44009(II2cBus i2cBus, byte address = null)

Parameters

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

Methods

Initialize()

Initalize the sensor

Declaration

protected void Initialize()

ReadSensor()

Reads data from the sensor

Declaration

protected override Task<Illuminance> ReadSensor()

Returns

Type	Description
Task<Illuminance>	The latest sensor reading

Overrides

Meadow.Foundation.SamplingSensorBase<Illuminance>.ReadSensor()