// Arduino "Hello World" in Morse Code
// Author: Ryan Greenberg
// Date: September 3, 2009

// Timing is done using this schema
// International Morse code is composed of five elements:
//      short mark, dot or 'dit' (.) - one unit long
//      longer mark, dash or 'dah' (-) - three units long
//      intra-character gap (between the dots and dashes within a character) - one unit long
//      short gap (between letters) - three units long
//      medium gap (between words) - seven units long[7]
// // http://en.wikipedia.org/wiki/Morse_code

int ledPin =  13;    // LED connected to digital pin 13
int unit = 300; // The base unit delay between each element. Equals one dot.

// The message to transmit repeatedly
char msg[12] = "HELLO WORLD";
//char msg[4] = "SOS";

// The characters in morse code
// 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    - - . .
char* morse[]={".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.."};
int sizes[]=  {2,    4,       4,      3,     1,   4,      3,     4,      2,    4,      3,     4,      2,    2,    3,     4,      4,      3,     3,     1,   3,     4,      3,     4,      4,      4};

void setup()   {                
  // initialize the digital pin as an output:
  pinMode(ledPin, OUTPUT);
}

// the loop() method runs over and over again,
// as long as the Arduino has power
void loop()                     
{
  int i
  for (i = 0; i < sizeof(msg) - 1; i++) { // sizeof - 1 for null character
    // Flash the letter if it is not space
    if (msg[i] >= 65 && msg[i] <= 90) {
      flashMorse(msg[i]);
      letterGap();
    } else {
      wordGap();
    }
  }
delay(5000); // Long delay before repeating message
}

void flashMorse(char c) {
    // A = 65, which corresponds to morse[0]
    // Z = 90, which corresponds to morse[25]
    int j;
    for (j = 0; j < sizes[c - 65]; j++) {
      switch (morse[c-65][j]) {
        case 46:
          // Dot
          dot();
          break;
        case 45:
          // Dash
          dash();
          break;
        default: 
          // Unknown   
          error();
      }
      
      // Delay display between dashes and dots
      dashDotGap();
    }
}

void dot() {
    digitalWrite(ledPin, HIGH);   // set the LED on
    delay(unit);
    digitalWrite(ledPin, LOW);    // set the LED off
}

void dash() {
    digitalWrite(ledPin, HIGH);   // set the LED on
    delay(unit * 3);
    digitalWrite(ledPin, LOW);    // set the LED off
}  

void dashDotGap() {
  delay(unit);
}

void letterGap() {
  delay(unit * 3);
}

void wordGap() {
  delay(unit * 7);
}

void error() {
  int k;
  for (k = 0; k < 5; k++) {
    digitalWrite(ledPin, HIGH);   // set the LED on
    delay(250);
    digitalWrite(ledPin, LOW);    // set the LED off
    delay(250);
  }
}