Remarks

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()
{
    Console.WriteLine("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++)
    {
        Console.WriteLine("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

Characteristic	Locus
Inheritance	System.Object > PiezoSpeaker
Namespace	Meadow.Foundation.Audio
Assembly	Meadow.Foundation.dll

Syntax

public class PiezoSpeaker : IToneGenerator

Constructors

PiezoSpeaker(IPwmOutputController, IPin)

Create a new PiezoSpeaker instance

Declaration

public PiezoSpeaker(IPwmOutputController device, IPin pin)

Parameters

Type	Name	Description
IPwmOutputController	device	IPwmOutputController to create PWM port
IPin	pin	PWM Pin connected to the PiezoSpeaker

PiezoSpeaker(IPwmOutputController, IPin, Frequency, Single)

Create a new PiezoSpeaker instance

Declaration

public PiezoSpeaker(IPwmOutputController device, IPin pin, Frequency frequency, float dutyCycle = null)

Parameters

Type	Name	Description
IPwmOutputController	device	IPwmOutputController to create PWM port
IPin	pin	PWM Pin connected to the PiezoSpeaker
Frequency	frequency	PWM frequency
System.Single	dutyCycle	Duty cycle

PiezoSpeaker(IPwmPort)

Create a new PiezoSpeaker instance

Declaration

public PiezoSpeaker(IPwmPort port)

Parameters

Type	Name	Description
IPwmPort	port

Properties

Port

Gets the port that is driving the Piezo Speaker

Declaration

protected IPwmPort Port { get; set; }

Property Value

Type	Description
IPwmPort

Methods

PlayTone(Frequency)

Play a frequency until stopped by StopTone

Declaration

public Task PlayTone(Frequency frequency)

Parameters

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

Returns

Type	Description
Task

PlayTone(Frequency, TimeSpan)

Play a frequency for a specified duration

Declaration

public Task PlayTone(Frequency frequency, TimeSpan duration)

Parameters

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

Returns

Type	Description
Task

StopTone()

Stops a tone playing

Declaration

public void StopTone()