Simple morse en- & decoding for Arduino (including LED Example)Build after the specs on http://en.wikipedia.org/wiki/Morse_code

LICENSE

Copyright (c) 2015 Matthias Esterl


Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:


The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.


THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

morse.ino

//Define the LED Pin
#define PIN_OUT        13
//Define unit length in ms
#define UNIT_LENGTH    250

//Build a struct with the morse code mapping
static const struct {const char letter, *code;} MorseMap[] =
{
	{ 'A', ".-" },
	{ 'B', "-..." },
	{ 'C', "-.-." },
	{ 'D', "-.." },
	{ 'E', "." },
	{ 'F', "..-." },
	{ 'G', "--." },
	{ 'H', "...." },
	{ 'I', ".." },
	{ 'J', ".---" },
	{ 'K', ".-.-" },
	{ 'L', ".-.." },
	{ 'M', "--" },
	{ 'N', "-." },
	{ 'O', "---" },
	{ 'P', ".--." },
	{ 'Q', "--.-" },
	{ 'R', ".-." },
	{ 'S', "..." },
	{ 'T', "-" },
	{ 'U', "..-" },
	{ 'V', "...-" },
	{ 'W', ".--" },
	{ 'X', "-..-" },
	{ 'Y', "-.--" },
	{ 'Z', "--.." },
	{ ' ', "     " }, //Gap between word, seven units 
		
	{ '1', ".----" },
	{ '2', "..---" },
	{ '3', "...--" },
	{ '4', "....-" },
	{ '5', "....." },
	{ '6', "-...." },
	{ '7', "--..." },
	{ '8', "---.." },
	{ '9', "----." },
	{ '0', "-----" },
		
	{ '.', "·–·–·–" },
	{ ',', "--..--" },
	{ '?', "..--.." },
	{ '!', "-.-.--" },
	{ ':', "---..." },
	{ ';', "-.-.-." },
	{ '(', "-.--." },
	{ ')', "-.--.-" },
	{ '"', ".-..-." },
	{ '@', ".--.-." },
	{ '&', ".-..." },
};

void setup()
{
  pinMode( PIN_OUT, OUTPUT );
  digitalWrite( PIN_OUT, LOW );
}

void loop()
{
  String morseWord = encode( "SIMP " );
    
  for(int i=0; i<=morseWord.length(); i++)
  {
    switch( morseWord[i] )
    {
      case '.': //dit
        digitalWrite( PIN_OUT, HIGH );
        delay( UNIT_LENGTH );
        digitalWrite( PIN_OUT, LOW );
        delay( UNIT_LENGTH );
          
        break;

      case '-': //dah
        digitalWrite( PIN_OUT, HIGH );
        delay( UNIT_LENGTH*3 );
        digitalWrite( PIN_OUT, LOW );
        delay( UNIT_LENGTH );
          
        break;

      case ' ': //gap
        delay( UNIT_LENGTH );
    }
  }
}

String encode(const char *string)
{
  size_t i, j;
  String morseWord = "";
  
  for( i = 0; string[i]; ++i )
  {
    for( j = 0; j < sizeof MorseMap / sizeof *MorseMap; ++j )
    {
      if( toupper(string[i]) == MorseMap[j].letter )
      {
        morseWord += MorseMap[j].code;
        break;
      }
    }
    morseWord += " "; //Add tailing space to seperate the chars
  }

  return morseWord;  
}

String decode(String morse)
{
  String msg = "";
  
  int lastPos = 0;
  int pos = morse.indexOf(' ');
  while( lastPos <= morse.lastIndexOf(' ') )
  {    
    for( int i = 0; i < sizeof MorseMap / sizeof *MorseMap; ++i )
    {
      if( morse.substring(lastPos, pos) == MorseMap[i].code )
      {
        msg += MorseMap[i].letter;
      }
    }

    lastPos = pos+1;
    pos = morse.indexOf(' ', lastPos);
    
    // Handle white-spaces between words (7 spaces)
    while( morse[lastPos] == ' ' && morse[pos+1] == ' ' )
    {
      pos ++;
    }
  }

  return msg;
}