#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

const int S0 = 2, S1 = 3, S2 = 4, S3 = 5;
const int SIG_PIN = 6; 
const int BUZZER_PIN = 9; 

// Added one more note for the 16th button!
int tones[] = {262, 294, 330, 349, 392, 440, 494, 523, 587, 659, 698, 784, 880, 988, 1047, 1109};
String noteNames[] = {"Do3", "Re3", "Mi3", "Fa3", "Sol3", "La3", "Si3", "Do4", "Re4", "Mi4", "Fa4", "Sol4", "La4", "Si4", "Do5", "Re5"};

int stableNote = -1;
//int readCount = 0;
const int STABLE_READS = 5;

void setup() {
  lcd.init();
  lcd.backlight();
  
  pinMode(S0, OUTPUT); 
  pinMode(S1, OUTPUT);
  pinMode(S2, OUTPUT); 
  pinMode(S3, OUTPUT);
  pinMode(SIG_PIN, INPUT_PULLUP); 
  pinMode(BUZZER_PIN, OUTPUT);
  
  noTone(BUZZER_PIN);

  lcd.setCursor(0, 0);
  lcd.print("  Piano Ready!  ");
  lcd.setCursor(0, 1);
  lcd.print("  Press a key   ");
}

int scanButtons() {
  // Changed from 15 to 16!
  for (int i = 0; i < 16; i++) {
    digitalWrite(S0, bitRead(i, 0));
    digitalWrite(S1, bitRead(i, 1));
    digitalWrite(S2, bitRead(i, 2));
    digitalWrite(S3, bitRead(i, 3));
    
    delay(1);
    
    if (digitalRead(SIG_PIN) == LOW) {
      return i;
    }
  }
  return -1;
}

void loop() {
  int detectedNote = scanButtons();
  
  // Count stable readings
  static int lastDetected = -1;
  static int sameCount = 0;
  
  if (detectedNote == lastDetected) {
    sameCount++;
  } else {
    sameCount = 0;
    lastDetected = detectedNote;
  }
  
  // Only change state after STABLE_READS consecutive identical readings
  if (sameCount >= STABLE_READS && detectedNote != stableNote) {
    
    if (detectedNote != -1) {
      // Start note
      tone(BUZZER_PIN, tones[detectedNote]);
      
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print(noteNames[detectedNote]);
      lcd.print(" ");
      lcd.print(tones[detectedNote]);
      lcd.print("Hz");
      
      lcd.setCursor(0, 1);
      lcd.print("BIN:");
      for (int b = 3; b >= 0; b--) {
        lcd.print(bitRead(detectedNote, b));
      }
      lcd.print(" CH:");
      lcd.print(detectedNote);
      
    } else {
      // Stop note
      noTone(BUZZER_PIN);
      
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("  Piano Ready!  ");
      lcd.setCursor(0, 1);
      lcd.print("  Press a key   ");
    }
    
    stableNote = detectedNote;
  }
  
  delay(5);
}