/*
  Murray Code Demonstration
  Arduino Uno

  Piezo buzzer on pin 8
*/

const int BUZZER = 8;

struct Murray {
  char letter;
  byte code;
};

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

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

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

  return 0;
}

void sendBit(bool bitVal) {

  if (bitVal)
    tone(BUZZER, 1200);
  else
    tone(BUZZER, 600);

  delay(150);

  noTone(BUZZER);
  delay(50);
}

void sendChar(char c) {

  byte code = lookup(c);

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

  for (int i = 4; i >= 0; i--) {
    bool bitVal = (code >> i) & 1;
    Serial.print(bitVal);
    sendBit(bitVal);
  }

  Serial.println();
  delay(300);
}

void setup() {

  Serial.begin(9600);

  Serial.println("Murray Code Demonstration");
  Serial.println("-------------------------");

  char msg[] = "HELLO";

  for (int i = 0; msg[i]; i++) {
    sendChar(msg[i]);
  }
}

void loop() {
}