Blink a message in Morse Code with an Arduino

morse.ino

/*
************************************************************************
Blink out a message in morse code
************************************************************************
*/

const int led = 13;
const char* message = "HELLO WORLD";
const int letter_unit_delay = 500;

void setup() {                
  pinMode(led, OUTPUT);     
}

void dit() {
  digitalWrite(led, HIGH);
  delay(letter_unit_delay);
  digitalWrite(led, LOW);
  delay(letter_unit_delay);
}

void daw() {
  digitalWrite(led, HIGH);
  delay(letter_unit_delay * 3);
  digitalWrite(led, LOW);
  delay(letter_unit_delay);
}

void blink_letter(char ch) {
  
  switch (ch) {
    case 'A': dit(); daw(); break;
    case 'B': daw(); dit(); dit(); dit(); break;
    case 'C': daw(); dit(); daw(); dit(); break;
    case 'D': daw(); dit(); dit(); break;
    case 'E': dit(); break;
    case 'F': dit(); dit(); daw(); dit(); break;
    case 'G': daw(); daw(); dit(); break;
    case 'H': dit(); dit(); dit(); dit(); break;
    case 'I': dit(); dit(); break;
    case 'J': dit(); daw(); daw(); daw(); break;
    case 'K': daw(); dit(); daw(); break;
    case 'L': dit(); daw(); dit(); dit(); break;
    case 'M': daw(); daw(); break;
    case 'N': daw(); dit(); break;
    case 'O': daw(); daw(); daw(); break;
    case 'P': dit(); daw(); daw(); dit(); break;
    case 'Q': daw(); daw(); dit(); daw(); break;
    case 'R': dit(); daw(); dit(); break;
    case 'S': dit(); dit(); dit(); break;
    case 'T': daw(); break;
    case 'U': dit(); dit(); daw(); break;
    case 'V': dit(); dit(); dit(); daw(); break;
    case 'W': dit(); daw(); daw(); break;
    case 'X': daw(); dit(); dit(); daw(); break;
    case 'Y': daw(); dit(); daw(); daw(); break;
    case 'Z': daw(); daw(); dit(); dit(); break;
    case '1': dit(); daw(); daw(); daw(); daw(); break;
    case '2': dit(); dit(); daw(); daw(); daw(); break;
    case '3': dit(); dit(); dit(); daw(); daw(); break;
    case '4': dit(); dit(); dit(); dit(); daw(); break;
    case '5': dit(); dit(); dit(); dit(); dit(); break;
    case '6': daw(); dit(); dit(); dit(); dit(); break;
    case '7': daw(); daw(); dit(); dit(); dit(); break;
    case '8': daw(); daw(); daw(); dit(); dit();break;
    case '9': daw(); daw(); daw(); daw(); dit(); break;
    case '0': daw(); daw(); daw(); daw(); daw(); break;
    case ' ': delay(letter_unit_delay * 4); break;
  }
  delay(letter_unit_delay * 3);
}

// this loop does a single message through the message
int pos = 0;
void loop() {
  if (pos < strlen(message)) {
    // Grab the next character and blink it out
    blink_letter(message[pos]);
    pos++;
  } else {
    // We've made it through the entire message.  Wait 5 seconds and start again
    delay(5000);
    pos = 0;
  }
}