/*
  Baudot (ITA2) Demonstration
  Arduino Uno R3

  Piezo Buzzer:
    + -> Pin 8
    - -> GND

  Serial Monitor: 9600 baud
*/

const int BUZZER = 8;

struct BaudotEntry {
  char letter;
  byte code;
};

// ITA2 LETTERS SHIFT TABLE
BaudotEntry baudotTable[] = {
  {'A', 0b00011},
  {'B', 0b11001},
  {'C', 0b01110},
  {'D', 0b01001},
  {'E', 0b00001},
  {'F', 0b01101},
  {'G', 0b11010},
  {'H', 0b10100},
  {'I', 0b00110},
  {'J', 0b01011},
  {'K', 0b01111},
  {'L', 0b10010},
  {'M', 0b11100},
  {'N', 0b01100},
  {'O', 0b11000},
  {'P', 0b10110},
  {'Q', 0b10111},
  {'R', 0b01010},
  {'S', 0b00101},
  {'T', 0b10000},
  {'U', 0b00111},
  {'V', 0b11110},
  {'W', 0b10011},
  {'X', 0b11101},
  {'Y', 0b10101},
  {'Z', 0b10001}
};

void setup() {
  Serial.begin(9600);

  Serial.println("Baudot (ITA2) Demonstration");
  Serial.println("--------------------------");

  sendMessage("HELLO");
}

void loop() {
  delay(5000);
}

byte getBaudot(char c) {
  c = toupper(c);

  for (unsigned int i = 0; i < sizeof(baudotTable)/sizeof(baudotTable[0]); i++) {
    if (baudotTable[i].letter == c) {
      return baudotTable[i].code;
    }
  }

  return 0;
}

void sendBit(bool bitValue) {

  if (bitValue) {
    tone(BUZZER, 1200);   // Logic 1
  } else {
    tone(BUZZER, 500);    // Logic 0
  }

  delay(150);

  noTone(BUZZER);
  delay(50);
}

void sendCharacter(char c) {

  byte code = getBaudot(c);

  Serial.print(c);
  Serial.print(" = ");

  // Print as 5-bit binary
  for (int bit = 4; bit >= 0; bit--) {
    Serial.print((code >> bit) & 1);
  }

  Serial.println();

  // Send bits MSB first
  for (int bit = 4; bit >= 0; bit--) {
    sendBit((code >> bit) & 1);
  }

  delay(300);
}

void sendMessage(const char *msg) {

  Serial.print("Message: ");
  Serial.println(msg);
  Serial.println();

  while (*msg) {

    if (*msg >= 'A' && *msg <= 'Z') {
      sendCharacter(*msg);
    }

    msg++;
  }
}