Remarks

AnalogLightSensor
Status
Source code	GitHub
NuGet package

Code Example

AnalogLightSensor analogLightSensor;

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

    // configure our AnalogLightSensor sensor
    analogLightSensor = new AnalogLightSensor(
        analogPin: Device.Pins.A03);

    //==== IObservable Pattern with an optional notification filter.
    var consumer = AnalogLightSensor.CreateObserver(
        handler: result => Resolver.Log.Info($"Observer filter satisfied: {result.New.Lux:N2} lux, old: {result.Old.Value.Lux:N2} lux"),

        // only notify if the change is greater than 0.5
        filter: result => {
            if (result.Old is { } old) 
            {   //c# 8 pattern match syntax. checks for !null and assigns var.
                return (result.New - old).Abs().Lux > 0.5; // returns true if > 0.5  change.
            }
            return false;
        }
        // if you want to always get notified, pass null for the filter:
        //filter: null
    );
    analogLightSensor.Subscribe(consumer);

    // classical .NET events can also be used:
    analogLightSensor.LuminosityUpdated += (sender, result) => 
        Resolver.Log.Info($"Lux changed: {result.New.Lux:N2} lux, old: {result.Old?.Lux:N2} lux");

    //==== One-off reading use case/pattern
    ReadIlluminance().Wait();

    // Spin up the sampling thread so that events are raised and IObservable notifications are sent.
    analogLightSensor.StartUpdating(TimeSpan.FromMilliseconds(1000));

    return Task.CompletedTask;
}

protected async Task ReadIlluminance()
{
    var illuminance = await analogLightSensor.Read();
    Resolver.Log.Info($"Initial lux: {illuminance.Lux:N2} lux");
}

Sample project(s) available on GitHub

Characteristic	Locus
Inheritance	System.Object ObservableBase<Illuminance> SamplingSensorBase<Illuminance> > AnalogLightSensor
Implements	ISamplingSensor<Illuminance> ILightSensor
Inherited Members	SamplingSensorBase<Illuminance>.samplingLock SamplingSensorBase<Illuminance>.Updated SamplingSensorBase<Illuminance>.SamplingTokenSource SamplingSensorBase<Illuminance>.Conditions SamplingSensorBase<Illuminance>.IsSampling SamplingSensorBase<Illuminance>.UpdateInterval SamplingSensorBase<Illuminance>.Read() ObservableBase<Illuminance>.observers ObservableBase<Illuminance>.NotifyObservers(IChangeResult<Illuminance>) ObservableBase<Illuminance>.Subscribe(IObserver<IChangeResult<Illuminance>>) ObservableBase<Illuminance>.CreateObserver(Action<IChangeResult<Illuminance>>, Nullable<Predicate<IChangeResult<Illuminance>>>)
Namespace	Meadow.Foundation.Sensors.Light
Assembly	Meadow.Foundation.dll

Syntax

public class AnalogLightSensor : SamplingSensorBase<Illuminance>, ISamplingSensor<Illuminance>, ILightSensor

Constructors

AnalogLightSensor(IAnalogInputPort, AnalogLightSensor.Calibration)

New instance of the AnalogLightSensor class.

Declaration

public AnalogLightSensor(IAnalogInputPort analogInputPort, AnalogLightSensor.Calibration calibration = null)

Parameters

Type	Name	Description
IAnalogInputPort	analogInputPort	Analog port the sensor is connected to.
AnalogLightSensor.Calibration	calibration	Calibration for the analog sensor.

AnalogLightSensor(IPin, AnalogLightSensor.Calibration, Int32, Nullable<TimeSpan>)

New instance of the AnalogLightSensor class.

Declaration

public AnalogLightSensor(IPin analogPin, AnalogLightSensor.Calibration calibration = null, int sampleCount = 5, TimeSpan? sampleInterval = null)

Parameters

Type	Name	Description
IPin	analogPin	Analog pin the sensor is connected to.
AnalogLightSensor.Calibration	calibration	Calibration for the analog sensor.
System.Int32	sampleCount	How many samples to take during a given reading. These are automatically averaged to reduce noise.
System.Nullable<TimeSpan>	sampleInterval	The time, in milliseconds, to wait in between samples during a reading.

Properties

AnalogInputPort

Analog port connected to sensor

Declaration

protected IAnalogInputPort AnalogInputPort { get; }

Property Value

Type	Description
IAnalogInputPort

Illuminance

Current illuminance value read by sensor

Declaration

public Illuminance? Illuminance { get; }

Property Value

Type	Description
System.Nullable<Illuminance>

LuminanceCalibration

Illuminance sensor callibration

Declaration

public AnalogLightSensor.Calibration LuminanceCalibration { get; protected set; }

Property Value

Type	Description
AnalogLightSensor.Calibration

Methods

RaiseEventsAndNotify(IChangeResult<Illuminance>)

Notify subscibers of LuminosityUpdated event hander

Declaration

protected override void RaiseEventsAndNotify(IChangeResult<Illuminance> changeResult)

Parameters

Type	Name	Description
IChangeResult<Illuminance>	changeResult	Change result with old and new Illuminance

Overrides

Meadow.Foundation.SamplingSensorBase<Illuminance>.RaiseEventsAndNotify(IChangeResult<Illuminance>)

ReadSensor()

Convenience method to get the current luminance. For frequent reads, use StartSampling() and StopSampling() in conjunction with the SampleBuffer.

Declaration

protected override Task<Illuminance> ReadSensor()

Returns

Type	Description
Task<Illuminance>

Overrides

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

StartUpdating(Nullable<TimeSpan>)

Starts continuously sampling the sensor.

This method also starts raising Changed events and IObservable subscribers getting notified. Use the readIntervalDuration parameter to specify how often events and notifications are raised/sent.

Declaration

public override void StartUpdating(TimeSpan? updateInterval)

Parameters

Type	Name	Description
System.Nullable<TimeSpan>	updateInterval	A TimeSpan that specifies how long to wait between readings. This value influences how often *Updated events are raised and IObservable consumers are notified. The default is 5 seconds.

Overrides

Meadow.Foundation.SamplingSensorBase<Illuminance>.StartUpdating(System.Nullable<TimeSpan>)

StopUpdating()

Stops sampling the temperature.

Declaration

public override void StopUpdating()

Overrides

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

VoltageToLuminance(Voltage)

Converts a voltage value to a level in centimeters, based on the current calibration values.

Declaration

protected Illuminance VoltageToLuminance(Voltage voltage)

Parameters

Type	Name	Description
Voltage	voltage

Returns

Type	Description
Illuminance

Events

LuminosityUpdated

Raised when the value of the reading changes.

Declaration

public event EventHandler<IChangeResult<Illuminance>> LuminosityUpdated

Event Type

Type	Description
EventHandler<IChangeResult<Illuminance>>