Remarks

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

The Max44009 is an analog ambient light sensor.

Code Example

Max44009 sensor;

public MeadowApp()
{
    Console.WriteLine("Initializing...");

    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 => Console.WriteLine($"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) => {
        Console.WriteLine($"Light: {result.New.Lux:N2}Lux");
    };

    //==== one-off read
    ReadConditions().Wait();

    // start updating continuously
    sensor.StartUpdating(TimeSpan.FromSeconds(1));
}

protected async Task ReadConditions()
{
    var result = await sensor.Read();
    Console.WriteLine("Initial Readings:");
    Console.WriteLine($"   Light: {result.Lux:N2}Lux");
}

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

Syntax

public class Max44009 : ByteCommsSensorBase<Illuminance>, IDisposable

Constructors

Max44009(II2cBus, Byte)

Declaration

public Max44009(II2cBus i2cBus, byte address = null)

Parameters

Type	Name	Description
II2cBus	i2cBus
System.Byte	address

Methods

Initialize()

Declaration

protected void Initialize()

ReadSensor()

Declaration

protected override Task<Illuminance> ReadSensor()

Returns

Type	Description
Task<Illuminance>

Overrides

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