Piezo

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
});

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

• Piezo