send a morse code signal by way of the OK LED on a raspberry pi

ledtest.js

// Copyright (c) 2014, Meadhbh S. Hamrick 
// All rights reserved. 
// 
// Redistribution and use in source and binary forms, with or without 
// modification, are permitted provided that the following conditions are 
// met: 
// 
//  * Redistributions of source code must retain the above copyright 
//    notice, this list of conditions and the following disclaimer. 
//  * Redistributions in binary form must reproduce the above copyright 
//    notice, this list of conditions and the following disclaimer in the 
//    documentation and/or other materials provided with the distribution. 
//  * Neither the name of Smithee, Spelvin, Agnew & Plinge nor the names of 
//    its contributors may be used to endorse or promote products derived 
//    from this software without specific prior written permission. 
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS 
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 
// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 
// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER 
// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

var fs = require( 'fs' );

var buffers = [
  ( new Buffer( "0\n" ) ),
  ( new Buffer( "1\n" ) )
];
var current = 0;
var element_len = 240;

var elements = {
  ' ': 2,
  '.': 6
};

var letters = {
  'a': [ 'dot', 'dash' ],
  'b': [ 'dash', 'dot', 'dot', 'dot' ],
  'c': [ 'dash', 'dot', 'dash', 'dot' ],
  'd': [ 'dash', 'dot', 'dot' ],
  'e': [ 'dot' ],
  'f': [ 'dot', 'dot', 'dash', 'dot' ],
  'g': [ 'dash', 'dash', 'dot' ],
  'h': [ 'dot', 'dot', 'dot', 'dot' ],
  'i': [ 'dot', 'dot' ],
  'j': [ 'dot', 'dash', 'dash', 'dash' ],
  'k': [ 'dash', 'dot', 'dash' ],
  'l': [ 'dot', 'dash', 'dot', 'dot'],
  'm': [ 'dash', 'dash' ],
  'n': [ 'dash', 'dot' ],
  'o': [ 'dash', 'dash', 'dash'  ],
  'p': [ 'dot', 'dash', 'dash', 'dot' ],
  'q': [ 'dash', 'dash', 'dot', 'dash' ],
  'r': [ 'dot', 'dash', 'dot' ],
  's': [ 'dot', 'dot', 'dot' ],
  't': [ 'dash' ],
  'u': [ 'dot', 'dot', 'dash' ],
  'v': [ 'dot', 'dot', 'dot', 'dash' ],
  'w': [ 'dot', 'dash', 'dash' ],
  'x': [ 'dash', 'dot', 'dot', 'dash' ],
  'y': [ 'dash', 'dot', 'dash', 'dash' ],
  'z': [ 'dash', 'dash', 'dot', 'dot' ],
  '1': [ 'dot', 'dash', 'dash', 'dash' ],
  '2': [ 'dot', 'dot', 'dash', 'dash', 'dash' ],
  '3': [ 'dot', 'dot', 'dot', 'dash', 'dash' ],
  '4': [ 'dot', 'dot', 'dot', 'dot', 'dash' ],
  '5': [ 'dot', 'dot', 'dot', 'dot', 'dot' ],
  '6': [ 'dash', 'dot', 'dot', 'dot', 'dot' ],
  '7': [ 'dash', 'dash', 'dot', 'dot', 'dot' ],
  '8': [ 'dash', 'dash', 'dash', 'dot', 'dot' ],
  '9': [ 'dash', 'dash', 'dash', 'dash', 'dot', ],
  '0': [ 'dash', 'dash', 'dash', 'dash', 'dash' ],
};

var message = "out of cheese error. rebooting universe.";
//var message = "watson come here. i need you";                                                                                     
//var message = "sos";                                                                                                              

var events = [];

for( var i = 0; i < message.length; i++ ) {
  var c = message.substr( i, 1 ).toLowerCase();
  if( letters[ c ] ) {
    for( var j = 0; j < letters[ c ].length; j++ ) {
      if( 'dot' == letters[c][j] ) {
        events.push( 1 );
        events.push( 0 );
      } else {
        events.push( 1 );
        events.push( 1 );
        events.push( 1 );
        events.push( 0 );
      }
    }
  } else if( elements[ c ] ) {
    for( var j = 0; j < elements[ c ]; j++ ) {
      events.push( 0 );
    }
  }
}

console.log( events );

var fd = fs.openSync( '/sys/class/leds/led0/brightness', 'w' );

var interval = setInterval( function () {
  if( current < events.length ) {
    if( 'undefined' != typeof events[ current ] ) {
      fs.writeSync( fd, buffers[ events[ current ] ], 0, buffers[ events[ current ] ].length );
    }
    current++;
  } else {
    clearInterval( interval );
    fs.closeSync( fd );
  }
}, 120 );