Remarks

AnalogWaterLevel
Status
Source code	GitHub
NuGet package

The analog water level sensor will output a voltage based on the amount of conductivity detected across the sensor area. Most sensors will jump to a signal of about ~1V as soon as the sensor area touches water and the voltage increases linearly as the depth increases.

Be careful to limit the water contact to only the the sensor area. Do not submerge the water level sensor.

Code Example

AnalogWaterLevel analogWaterLevel;

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

    // configure our AnalogWaterLevel sensor
    analogWaterLevel = new AnalogWaterLevel(
        analogPin: Device.Pins.A00
    );

    // Example that uses an IObservable subscription to only be notified
    // when the level changes by at least 0.1cm
    analogWaterLevel.Subscribe(AnalogWaterLevel.CreateObserver(
        h => Resolver.Log.Info($"Water level changed by 10 mm; new: {h.New}, old: {h.Old}"),
        null //e => { return Math.Abs(e.Delta) > 0.1f; }
    ));

    // classical .NET events can also be used:
    analogWaterLevel.Updated += (object sender, IChangeResult<float> e) => {
        Resolver.Log.Info($"Level Changed, level: {e.New}cm");
    };

    // Get an initial reading.
    ReadLevel().Wait();

    // Spin up the sampling thread so that events are raised and IObservable notifications are sent.
    analogWaterLevel.StartUpdating(TimeSpan.FromSeconds(5));

    return Task.CompletedTask;
}

protected async Task ReadLevel()
{
    var conditions = await analogWaterLevel.Read();
    Resolver.Log.Info($"Initial level: { conditions }");
}

Sample project(s) available on GitHub

Wiring Example

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

AnalogWaterLevel	Meadow Pin
GND	GND
IN	A00
VCC	3.3V

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

Syntax

public class AnalogWaterLevel : SamplingSensorBase<float>, ISamplingSensor<float>

Constructors

AnalogWaterLevel(IAnalogInputPort, AnalogWaterLevel.Calibration)

New instance of the AnalogWaterLevel class.

Declaration

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

Parameters

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

AnalogWaterLevel(IPin, AnalogWaterLevel.Calibration, Nullable<TimeSpan>)

New instance of the AnalogWaterLevel class.

Declaration

public AnalogWaterLevel(IPin analogPin, AnalogWaterLevel.Calibration calibration = null, TimeSpan? updateInterval = null)

Parameters

Type	Name	Description
IPin	analogPin	Analog pin the sensor is connected to.
AnalogWaterLevel.Calibration	calibration	Calibration for the analog sensor.
System.Nullable<TimeSpan>	updateInterval	The time, in milliseconds, to wait between sets of sample readings. This value determines how often Changed events are raised and IObservable consumers are notified.

Properties

AnalogInputPort

AnalogInputPort connected to temperature sensor

Declaration

protected IAnalogInputPort AnalogInputPort { get; }

Property Value

Type	Description
IAnalogInputPort

LevelCalibration

Calibration of water level

Declaration

public AnalogWaterLevel.Calibration LevelCalibration { get; protected set; }

Property Value

Type	Description
AnalogWaterLevel.Calibration

WaterLevel

Water level

Declaration

public float WaterLevel { get; protected set; }

Property Value

Type	Description
System.Single

Methods

ReadSensor()

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

Declaration

protected override Task<float> ReadSensor()

Returns

Type	Description
Task<System.Single>

Overrides

Meadow.Foundation.SamplingSensorBase<System.Single>.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.

Overrides

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

StopUpdating()

Stops sampling the water level

Declaration

public override void StopUpdating()

Overrides

Meadow.Foundation.SamplingSensorBase<System.Single>.StopUpdating()

VoltageToWaterLevel(Voltage)

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

Declaration

protected float VoltageToWaterLevel(Voltage voltage)

Parameters

Type	Name	Description
Voltage	voltage

Returns

Type	Description
System.Single