Skip to content
Brad Buchanan edited this page Apr 13, 2017 · 16 revisions

The Piezo class constructs objects that represent a single piezo component attached to the physical board.

Parameters

  • pin A Number or String address for the Piezo (+) pin (digital):

    var piezo = new five.Piezo(3);
  • options An object of property parameters.

    Property Type Value/Description Default Required
    pin Number Digital Pin. yes

Shape

Property Name Description Read Only
board A reference to the board object the Led is attached to No
id A user definable id value. Defaults to null No
pin The pin address that the Led is attached to No
mode Mode the piezo's pin is set to: output (1). Yes
isPlaying Boolean: is the piezo currently playing? Yes

Component Initialization

Basic

new five.Piezo({
  pin: 3
});

piezo diagram

i2C backpack

  var piezo = new five.Piezo({
    controller: "I2C_BACKPACK",
    pin: 3
  });

Firmware: https://github.com/rwaldron/johnny-five/blob/master/firmwares/piezo_i2c_backpack.ino

Usage

var five = require("johnny-five");
var board = new five.Board();

board.on("ready", function() {

  // Create a standard `piezo` instance on pin 3
  var piezo = new five.Piezo(3);

  // Plays a song
  piezo.play({
    // song is composed by an array of pairs of notes and beats
    // The first argument is the note (null means "no note")
    // The second argument is the length of time (beat) of the note (or non-note)
    song: [
      ["C4", 1 / 4],
      ["D4", 1 / 4],
      ["F4", 1 / 4],
      ["D4", 1 / 4],
      ["A4", 1 / 4],
      [null, 1 / 4],
      ["A4", 1],
      ["G4", 1],
      [null, 1 / 2],
      ["C4", 1 / 4],
      ["D4", 1 / 4],
      ["F4", 1 / 4],
      ["D4", 1 / 4],
      ["G4", 1 / 4],
      [null, 1 / 4],
      ["G4", 1],
      ["F4", 1],
      [null, 1 / 2]
    ],
    tempo: 100
  });
});

API

  • frequency(frequency, duration) Play tone at frequency (in Hz) for duration milliseconds.

    piezo.frequency(587, 1000); // Play note d5 for 1 second
  • play(tune, callback) Play a tune with an optional callback to invoke when the tune is done playing. The tune object contains a song (an array of the notes in the tune) and optional settings (e.g. tempo):

    piezo.play({
      tempo: 150, // Beats per minute, default 150
      song: [ // An array of notes that comprise the tune
        [ "c4", 1 ], // Each element is an array in which 
                     // [0] is the note to play and 
                     //[1] is the duration in "beats" (tempo, above)
        [ "e4", 2 ],
        [ "g4", 3 ],
        [ null, 4 ] // null indicates "no tone" for the beats indicated
      ]
    });

    The notes you can use are defined in lib/piezo.js as Piezo.Notes:

    Piezo.Notes = {
      "c4": 262,
      "c#4": 277,
      "d4": 294,
      "d#4": 311,
      "e4": 330,
      "f4": 349,
      "f#4": 370,
      "g4": 392,
      "g#4": 415,
      "a4": 440,
      "a#4": 466,
      "b4": 494,
      "c5": 523,
      "c#5": 554,
      "d5": 587,
      "d#5": 622,
      "e5": 659,
      "f5": 698,
      "f#5": 740,
      "g5": 784,
      "g#5": 831,
      "a5": 880,
      "a#5": 932,
      "b5": 988,
      "c6": 1047
    };

    You can also use frequencies directly if you'd like:

    piezo.play({
      song: [
        [ 698, 1 ], // Play frequency 698 for 1 beat
        [ 831, 2 ] // ...
      ]
    });
  • tone(tone, duration) Play a tone for duration ms. The tone value in this case is a computed duty cycle (in microseconds). This is a lower-level method than frequency (which does the translation from frequency to tone for you). Most of the time you likely want to use frequency.

  • noTone Stop tone playing from Piezo. Will immediately stop playing a tone (digitalWrite the output pin low) and clear any existing queued tone timers.

  • off Alias of noTone

Events

Piezo objects are output only and therefore do not emit any events.

Examples

You can’t perform that action at this time.