Meadow.Foundation.Audio.PiezoSpeaker

PiezoSpeaker
Status
Source code	GitHub
NuGet package

The PiezoSpeaker class represents a piezoelectric speaker that can be used to generate tones across a range of frequencies. They typically perform well between 1-5kHz but may go as high as 100kHz. PiezoSpeaker Implements IToneGenerator.

The positive pin of the piezo speaker connects to a pulse width modulation (PWM) capable pin on the Meadow and the negative pin connects to common/ground. A resistor can be placed in-line to reduce volume.

Code Example

protected PiezoSpeaker piezoSpeaker;

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

    piezoSpeaker = new PiezoSpeaker(Device.CreatePwmPort(Device.Pins.D05, new Frequency(100, Frequency.UnitType.Hertz)));

    return Task.CompletedTask;
}

public override async Task Run()
{
    for (int i = 0; i < 5; i++)
    {
        Resolver.Log.Info("Playing A major triad starting at A4");
        await piezoSpeaker.PlayTone(new Frequency(440, Frequency.UnitType.Hertz), TimeSpan.FromMilliseconds(500)); //A
        await piezoSpeaker.PlayTone(new Frequency(554.37f, Frequency.UnitType.Hertz), TimeSpan.FromMilliseconds(500)); //C#
        await piezoSpeaker.PlayTone(new Frequency(659.25f, Frequency.UnitType.Hertz), TimeSpan.FromMilliseconds(500)); //E

        await Task.Delay(2500);
    }
}

Sample project(s) available on GitHub

Wiring Example

Class PiezoSpeaker

Represents a 2 pin piezo-electric speaker capable of generating tones

Assembly: Meadow.Foundation.dll

View Source

Declaration

public class PiezoSpeaker : IToneGenerator, IDisposable

Implements:
Meadow.Peripherals.Speakers.IToneGenerator, System.IDisposable

Properties

Volume

The volume from 0-1 Defined by the PWM port duty cycle from 0 to 0.5

View Source

Declaration

public float Volume { get; protected set; }

Port

Gets the port that is driving the Piezo Speaker

View Source

Declaration

protected IPwmPort Port { get; set; }

IsDisposed

Is the object disposed

View Source

Declaration

public bool IsDisposed { get; }

Methods

PlayTone(Frequency)

Play a frequency until stopped by StopTone

View Source

Declaration

public Task PlayTone(Frequency frequency)

Returns

System.Threading.Tasks.Task

Parameters

Type	Name	Description
Meadow.Units.Frequency	frequency	The frequency in hertz of the tone to be played

PlayTone(Frequency, TimeSpan)

Play a frequency for a specified duration

View Source

Declaration

public Task PlayTone(Frequency frequency, TimeSpan duration)

Returns

System.Threading.Tasks.Task

Parameters

Type	Name	Description
Meadow.Units.Frequency	frequency	The frequency in hertz of the tone to be played
System.TimeSpan	duration	How long the note is played in milliseconds, if duration is 0, tone plays indefinitely

StopTone()

Stops a tone playing

View Source

Declaration

public void StopTone()

SetVolume(float)

Set the playback volume

View Source

Declaration

public void SetVolume(float volume)

Parameters

Type	Name	Description
System.Single	volume	The volume from 0 (off) to 1 (max volume)

Dispose()

Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

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Declaration

public void Dispose()

Dispose(bool)

Dispose of the object

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Declaration

protected virtual void Dispose(bool disposing)

Parameters

Type	Name	Description
System.Boolean	disposing	Is disposing

Implements

• Meadow.Peripherals.Speakers.IToneGenerator
• System.IDisposable