/*
  The timing in Morse code is based around the length of one "dit"
  (or "dot" if you like). From the dit length we can derive the length
  of a "dah" (or "dash") and the various pauses:

  Dit: 1 unit
  Dah: 3 units
  Intra-character space (the gap between dits and dahs within a character): 1 unit
  Inter-character space (the gap between the characters of a word): 3 units
  Word space (the gap between two words): 7 units

  https://morsecode.world/international/timing.html

*/

const int UNIT_TIME = 150;  // sets Morse speed

const int BUZZ_PIN = 8;
const int LED_PIN =  9;

const int DOT_TIME = UNIT_TIME;
const int DASH_TIME = UNIT_TIME * 3;
const int SYMBOL_SPACE = UNIT_TIME;
const int CHAR_SPACE = UNIT_TIME * 3;
const int WORD_SPACE = UNIT_TIME * 7;

void writeDot() {
  digitalWrite(LED_PIN, HIGH);
  tone(BUZZ_PIN, 1000);
  delay(DOT_TIME);
  digitalWrite(LED_PIN, LOW);
  noTone(BUZZ_PIN);
  delay(SYMBOL_SPACE);
}

void writeDash()  {
  digitalWrite(LED_PIN, HIGH);
  tone(BUZZ_PIN, 1000);
  delay(DASH_TIME);
  digitalWrite(LED_PIN, LOW);
  noTone(BUZZ_PIN);
  delay(SYMBOL_SPACE);
}

void writeCharSpc() {
  delay(CHAR_SPACE);
}

void writeWordSpc() {
  delay(WORD_SPACE);
}

void setup() {
  //Set pins to OUTPUT
  pinMode(BUZZ_PIN, OUTPUT);
  pinMode (9, OUTPUT);
}

void loop() {
  // write "S"
  writeDash();
  writeDash();
  writeDash();
  // next letter
  writeCharSpc();
  // write "O"
  writeDot();
  writeDot();
  writeDot();
  // next letter
  writeCharSpc();
  // write "S"
  writeDash();
  writeDash();
  writeDash();
  // next word
  writeWordSpc();
}