Remarks

Hcsr04
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

The HC-SR04 ultrasonic sensor uses sonar to determine distance to an object (like bats). It offers excellent non-contact range detection with high accuracy and stable readings in an easy-to-use package.

Code Example

Hcsr04 hCSR04;

public override Task Initialize()
{
    Resolver.Log.Info($"Hello HC-SR04 sample");

    hCSR04 = new Hcsr04(
        triggerPin: Device.Pins.D05,
        echoPin: Device.Pins.D06);
    hCSR04.DistanceUpdated += HCSR04_DistanceUpdated;

    return Task.CompletedTask;
}

public override Task Run()
{
    while (true)
    {
        // Sends a trigger signal
        hCSR04.MeasureDistance();
        Thread.Sleep(2000);
    }
}

private void HCSR04_DistanceUpdated(object sender, IChangeResult<Meadow.Units.Length> e)
{
    Resolver.Log.Info($"Distance (cm): {e.New.Centimeters}");
}

Sample project(s) available on GitHub

Purchasing

The HC-SR04 sensor is available from Sparkfun:

• Ultrasonic Sensor - HC-SR04

Sample projects available on GitHub

Wiring Example

Characteristic	Locus
Inheritance	System.Object ObservableBase<Length> SamplingSensorBase<Length> > Hcsr04 > SerialWombatBase.Hcsr04
Implements	ISamplingSensor<Length> IRangeFinder
Inherited Members	SamplingSensorBase<Length>.samplingLock SamplingSensorBase<Length>.Updated SamplingSensorBase<Length>.SamplingTokenSource SamplingSensorBase<Length>.Conditions SamplingSensorBase<Length>.IsSampling SamplingSensorBase<Length>.UpdateInterval SamplingSensorBase<Length>.RaiseEventsAndNotify(IChangeResult<>) SamplingSensorBase<Length>.Read() ObservableBase<Length>.observers ObservableBase<Length>.NotifyObservers(IChangeResult<>) Meadow.Foundation.ObservableBase<Length>.Subscribe(IObserver<>) Meadow.Foundation.ObservableBase<Length>.CreateObserver(Action<>, System.Nullable<Predicate<IChangeResult<UNIT>>>)
Namespace	Meadow.Foundation.Sensors.Distance
Assembly	Hcsr04.dll

Syntax

public class Hcsr04 : SamplingSensorBase<Length>, ISamplingSensor<Length>, IRangeFinder

Constructors

Hcsr04()

Create a new HCSR04 object

Declaration

protected Hcsr04()

Hcsr04(IDigitalOutputPort, IDigitalInputPort)

Create a new HCSR04 object

Declaration

public Hcsr04(IDigitalOutputPort triggerPort, IDigitalInputPort echoPort)

Parameters

Type	Name	Description
IDigitalOutputPort	triggerPort	The port for the trigger pin
IDigitalInputPort	echoPort	The port for the echo pin

Hcsr04(IPin, IPin)

Create a new HCSR04 object with an IO Device

Declaration

public Hcsr04(IPin triggerPin, IPin echoPin)

Parameters

Type	Name	Description
IPin	triggerPin	The trigger pin
IPin	echoPin	The echo pin

Fields

echoPort

Port for echo Pin

Declaration

protected IDigitalInputPort echoPort

Field Value

Type	Description
IDigitalInputPort

triggerPort

Port for trigger Pin

Declaration

protected IDigitalOutputPort triggerPort

Field Value

Type	Description
IDigitalOutputPort

Properties

Distance

Returns current distance

Declaration

public Length? Distance { get; protected set; }

Property Value

Type	Description
System.Nullable<Length>

MaximumDistance

Maximum valid distance in cm

Declaration

public double MaximumDistance { get; }

Property Value

Type	Description
System.Double

MinimumDistance

Minimum valid distance in cm

Declaration

public double MinimumDistance { get; }

Property Value

Type	Description
System.Double

Methods

MeasureDistance()

Sends a trigger signal

Declaration

public virtual void MeasureDistance()

RaiseEventsAndNotify(IChangeResult<Length>)

Raise events for subcribers and notify of value changes

Declaration

protected override void RaiseEventsAndNotify(IChangeResult<Length> changeResult)

Parameters

Type	Name	Description
IChangeResult<Length>	changeResult	The updated sensor data

ReadSensor()

Reads data from the sensor

Declaration

protected override Task<Length> ReadSensor()

Returns

Type	Description
Task<Length>	The latest sensor reading

Overrides

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

StartUpdating(Nullable<TimeSpan>)

Starts continuously sampling the sensor

Declaration

public override void StartUpdating(TimeSpan? updateInterval = null)

Parameters

Type	Name	Description
System.Nullable<TimeSpan>	updateInterval

StopUpdating()

Stops sampling the sensor

Declaration

public override void StopUpdating()

Overrides

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

Events

DistanceUpdated

Raised when an received a rebound trigger signal

Declaration

public event EventHandler<IChangeResult<Length>> DistanceUpdated

Event Type

Type	Description
EventHandler<IChangeResult<Length>>