PWMSoundOutput

This example shows how to use the PWMOut to generate notes. It plays three tones repeatedly.

What you need

• SwiftIO board

• Jumper wires

• Buzzer

• SwiftIO shield (optional)

Circuit

Code

// Produce different notes by changing the frequency of PWM signal.

// Import the library to enable the relevant classes and functions.
import SwiftIO

// Initialize a PWM output pin the speaker is connected to.
let speaker = PWMOut(Id.PWM2B)

// Specify several frequencies to produce different sound.
let fre = [262, 294, 330]

/// Play recurrently these notes.
while true {
    for f in fre {
        // Set the frequency and the duty cycle of output to produce each note.
        speaker.set(frequency: f, dutycycle: 0.5)
        // Play each note for one second.
        sleep(ms: 1000)
    }

}

Instruction

The code above uses a Frequency as musical pitches. For example, NOTE_C4 is middle C, whose frequency is 262 Hz. Latter example MidiPlayer we will markdown all this musical note in a file. This file contains all the pitch values for typical notes. You may find it useful whenever you want to make musical notes.

See Also

• PWMOut - The PWMOut class is used to change the time of high voltage during one period to simulate different output.

References

• Frequency and Pitch

• Online Tone Generator

• wiki: Pitch (music)