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:

Class Bh1745

Represents a BH1745 Luminance and Color Sensor

Assembly: Bh1745.dll

View Source

Declaration

public class Bh1745 : ByteCommsSensorBase<(Illuminance? AmbientLight, Color? Color, bool Valid)>, IObservable<IChangeResult<(Illuminance? AmbientLight, Color? Color, bool Valid)>>, ISamplingSensor<(Illuminance? AmbientLight, Color? Color, bool Valid)>, ISensor<(Illuminance? AmbientLight, Color? Color, bool Valid)>, IDisposable, ILightSensor, ISamplingSensor<Illuminance>, ISensor<Illuminance>, ISensor, ISamplingSensor, II2cPeripheral

Inheritance: System.Object -> Meadow.Foundation.ObservableBase<UNIT>

Implements:

Expand

System.IObservable<Meadow.IChangeResult<System.ValueTuple<System.Nullable<Meadow.Units.Illuminance>,System.Nullable<Meadow.Color>,System.Boolean>>>, Meadow.Peripherals.Sensors.ISamplingSensor<System.ValueTuple<System.Nullable<Meadow.Units.Illuminance>,System.Nullable<Meadow.Color>,System.Boolean>>, Meadow.Peripherals.Sensors.ISensor<System.ValueTuple<System.Nullable<Meadow.Units.Illuminance>,System.Nullable<Meadow.Color>,System.Boolean>>, System.IDisposable, Meadow.Peripherals.Sensors.Light.ILightSensor, Meadow.Peripherals.Sensors.ISamplingSensor<Meadow.Units.Illuminance>, Meadow.Peripherals.Sensors.ISensor<Meadow.Units.Illuminance>, Meadow.Peripherals.Sensors.ISensor, Meadow.Peripherals.Sensors.ISamplingSensor, Meadow.Hardware.II2cPeripheral

Properties

Illuminance

The current Illuminance value

View Source

Declaration

public Illuminance? Illuminance { get; }

InterruptReset

Interrupt reset status

View Source

Declaration

public Bh1745.InterruptStatus InterruptReset { get; set; }

MeasurementTime

Gets or sets the currently set measurement time

View Source

Declaration

public Bh1745.MeasurementTimeType MeasurementTime { get; set; }

IsMeasurementActive

Is the sensor actively measuring

View Source

Declaration

public bool IsMeasurementActive { get; set; }

AdcGain

Gets or sets the ADC gain of the sensor

View Source

Declaration

public Bh1745.AdcGainTypes AdcGain { get; set; }

InterruptSignalIsActive

Is the interrupt active

View Source

Declaration

public bool InterruptSignalIsActive { get; }

LatchBehavior

Gets or sets how the interrupt pin latches

View Source

Declaration

public Bh1745.LatchBehaviorTypes LatchBehavior { get; set; }

InterruptSource

Gets or sets the source channel that triggers the interrupt

View Source

Declaration

public Bh1745.InterruptChannels InterruptSource { get; set; }

InterruptIsEnabled

Gets or sets whether the interrupt pin is enabled

View Source

Declaration

public bool InterruptIsEnabled { get; set; }

InterruptPersistence

Gets or sets the persistence function of the interrupt

View Source

Declaration

public Bh1745.InterruptTypes InterruptPersistence { get; set; }

LowerInterruptThreshold

Gets or sets the lower interrupt threshold

View Source

Declaration

public ushort LowerInterruptThreshold { get; set; }

UpperInterruptThreshold

Gets or sets the upper interrupt threshold

View Source

Declaration

public ushort UpperInterruptThreshold { get; set; }

CompensationMultipliers

Gets or sets the channel compensation multipliers which are used to scale the channel measurements

View Source

Declaration

public Bh1745.ChannelMultipliers CompensationMultipliers { get; set; }

DefaultI2cAddress

The default I2C address for the peripheral

View Source

Declaration

public byte DefaultI2cAddress { get; }

Methods

ReadSensor()

Reads data from the sensor

View Source

Declaration

protected override Task<(Illuminance? AmbientLight, Color? Color, bool Valid)> ReadSensor()

Returns

System.Threading.Tasks.Task<System.ValueTuple<System.Nullable<Meadow.Units.Illuminance>,System.Nullable<Meadow.Color>,System.Boolean>>: The latest sensor reading### RaiseEventsAndNotify(IChangeResult<(Illuminance? AmbientLight, Color? Color, bool Valid)>) Raise events for subscribers and notify of value changes

View Source

Declaration

protected override void RaiseEventsAndNotify(IChangeResult<(Illuminance? AmbientLight, Color? Color, bool Valid)> changeResult)

Parameters

Type	Name	Description
Meadow.IChangeResult<System.ValueTuple<System.Nullable<Meadow.Units.Illuminance>,System.Nullable<Meadow.Color>,System.Boolean>>	changeResult	The updated sensor data

Reset()

Resets the device to the default configuration On reset the sensor goes to power down mode

View Source

Declaration

protected void Reset()

ReadMeasurementIsValid()

Reads whether the last measurement is valid

View Source

Declaration

protected bool ReadMeasurementIsValid()

Returns

System.Boolean

ReadRedDataRegister()

Reads the red data register of the sensor

View Source

Declaration

protected ushort ReadRedDataRegister()

Returns

System.UInt16

ReadGreenDataRegister()

Reads the green data register of the sensor

View Source

Declaration

protected ushort ReadGreenDataRegister()

Returns

System.UInt16

ReadBlueDataRegister()

Reads the blue data register of the sensor

View Source

Declaration

protected ushort ReadBlueDataRegister()

Returns

System.UInt16

ReadClearDataRegister()

Reads the clear data register of the sensor

View Source

Declaration

protected ushort ReadClearDataRegister()

Returns

System.UInt16

Implements

• System.IObservable<Meadow.IChangeResult<System.ValueTuple<System.Nullable<Meadow.Units.Illuminance>,System.Nullable<Meadow.Color>,System.Boolean>>>
• Meadow.Peripherals.Sensors.ISamplingSensor<System.ValueTuple<System.Nullable<Meadow.Units.Illuminance>,System.Nullable<Meadow.Color>,System.Boolean>>
• Meadow.Peripherals.Sensors.ISensor<System.ValueTuple<System.Nullable<Meadow.Units.Illuminance>,System.Nullable<Meadow.Color>,System.Boolean>>
• System.IDisposable
• Meadow.Peripherals.Sensors.Light.ILightSensor
• Meadow.Peripherals.Sensors.ISamplingSensor<Meadow.Units.Illuminance>
• Meadow.Peripherals.Sensors.ISensor<Meadow.Units.Illuminance>
• Meadow.Peripherals.Sensors.ISensor
• Meadow.Peripherals.Sensors.ISamplingSensor
• Meadow.Hardware.II2cPeripheral