DAH-DI-DAH-DIT DAH-DI-DAH-DAH

Created by CoderDojo Dublin / @coderdojodublin

Connect to WiFi

  • Network: Zalando_Dublin
  • Password: Z4land0!

Demo

Play

Agenda

When?What?
13:00 - 13:15Registration & set-up
13:15 - 14:20Part #1 - Text to code
14:20 - 14:40Break
14:40 - 15:45Part #2 - Code to sound
15:45 - 16:00Presentations

Links

Basic Page


<html>
  <head>
    <script type="type/javascript">
      function playMessage() {
        alert(document.forms['morse'].message.value);
      }
    </script>
  </head>
  <body>
    <form name="morse">
	  <input name="message" type="text" />
	  <a href="javascript:playMessage()">Play</a>
	</form>
  </body>
<html>

To morse code


var LOOKUP_TABLE = { "O": "---", "S": "..." };

function translateCharacter(ch) {
  var translated = LOOKUP_TABLE[ch.toUpperCase()];
  return translated != undefined ? translated : '';
}

function playMessage() {
  var message = document.forms['morse'].message.value;
  var morse = '';
  for (var i = 0; i < message.length; i++)
    morse += message[i] == ' ' ? ' ' : translateCharacter(message[i]);
  alert(morse);
}

Morse Code

A.-B-...C-.-.D-..E.F..-.
G--.H....I..J.---K-.-L.-..
M--N-.O---P.--.Q--.-R.-.
S...T-U..-W.--V...-X-..-
Y-.--Z--..
1.----2..---3...--4....-5.....6-....
7--...8---..9----.0-----

Time for a break

Tones

ElementTime units
dot1
dash3
between dots & dashes1
between letters3
between words3

Be Cool

-... . -.-. --- --- .-..

Make some noise


function MorsePlayer(ac, rate) {
  this._oscillator = ac.createOscillator();
  this._oscillator.frequency.value = 750;
  this._oscillator.connect(ac.destination);
  this._oscillator.start(0);
}

var ac = new (window.AudioContext || window.webkitAudioContext)();
var player = new MorsePlayer(ac);

Peace & Quiet


function MorsePlayer(ac, rate) {
  this._oscillator = ac.createOscillator();
  this._gain = ac.createGain();
  this._gain.gain.value = 0;
  this._oscillator.frequency.value = 750;
  this._oscillator.connect(this._gain);
  if(rate == undefined) {
    rate = 20;
  }
  this._dot = 1.2 / rate; 
  this._oscillator.start(0);
}

MorsePlayer.prototype.connect = function(target) {
  return this._gain.connect(target);
}

var ac = new (window.AudioContext || window.webkitAudioContext)();
var player = new MorsePlayer(ac);
player.connect(ac.destination);

Play Code


MorsePlayer.prototype.playCode = function(time, code) {
  for(var i = 0; i < code.length; i++) {
    this._gain.gain.setValueAtTime(1.0, time);
    switch(code[i]) {
      case '.':
        time += this._dot;
        break;
      case '-':
        time += 3 * this._dot;
        break;
    }
    this._gain.gain.setValueAtTime(0.0, time);
    time += this._dot;
  }
  return time;
}
					

Play S

Last step


function playMessage() {
  player.playMessage(ac.currentTime, document.forms['morse'].message.value);
  return false;
}
					

MorsePlayer.prototype.playMessage = function(time, message) {
  for (var i = 0; i < message.length; i++) {
    if (message[i] == ' ') {
      time += 3 * this._dot;
    } else {
      var code = translateCharacter(message[i]);
      time = player.playCode(time, code);
      time += 2 * this._dot;
    }
  }
}