Meadow.Foundation.Sensors.Light.Bh1745

Bh1745
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

The BH1745 is a RGB color and luminance sensor that communicates over I2C.

Code Example

Bh1745 sensor;
RgbPwmLed rgbLed;

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

    sensor = new Bh1745(Device.CreateI2cBus());

    // instantiate our onboard LED that we'll show the color with
    rgbLed = new RgbPwmLed(
        Device.Pins.OnboardLedRed,
        Device.Pins.OnboardLedGreen,
        Device.Pins.OnboardLedBlue,
        commonType: CommonType.CommonAnode);

    // Example that uses an IObservable subscription to only be notified
    var consumer = Bh1745.CreateObserver(
        handler: result => Resolver.Log.Info($"Observer: filter satisfied: {result.New.AmbientLight?.Lux:N2}Lux, old: {result.Old?.AmbientLight?.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)
            {
                // returns true if > 100lux change
                return ((result.New.AmbientLight.Value - old.AmbientLight.Value).Abs().Lux > 100);
            }
            return false;
        });

    sensor.Subscribe(consumer);

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

        if (result.New.Color is { } color)
        {
            rgbLed.SetColor(color);
        }
    };

    return Task.CompletedTask;
}

public override async Task Run()
{
    var result = await sensor.Read();

    Resolver.Log.Info("Initial Readings:");
    Resolver.Log.Info($" Visible Light: {result.AmbientLight?.Lux:N2}Lux");
    Resolver.Log.Info($" Color: {result.Color}");

    if (result.Color is { } color)
    {
        rgbLed.SetColor(color);
    }

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

Sample project(s) available on GitHub

Wiring Example

To wire a Bh1745 to your Meadow board, connect the following:

Bh1745	Meadow Pin
GND	GND
SCL	D08 (SCL)
SDA	D07 (SDA)
VCC	3V3

It should look like the following diagram: