Remarks

Max44009
Status Status badge: working
Source code GitHub
Datasheet(s) GitHub
NuGet package NuGet Gallery for Meadow.Foundation.Sensors.Light.Max44009

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 > Max44009
Namespace Meadow.Foundation.Sensors.Light
Assembly Max44009.dll

Syntax

public class Max44009 : ByteCommsSensorBase<Illuminance>

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