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

LiquidCrystal_I2C lcd(0x27, 16, 2);

#define BUZZER 19
#define SERVO_PIN 18

int rowPins[4] = {13,12,14,27};
int colPins[4] = {26,25,33,32};

char keys[4][4] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

void setup() {

  Serial.begin(115200);

  lcd.init();
  lcd.backlight();

  pinMode(BUZZER, OUTPUT);
  pinMode(SERVO_PIN, OUTPUT);

  for(int i=0;i<4;i++){
    pinMode(rowPins[i], OUTPUT);
    digitalWrite(rowPins[i], HIGH);
    pinMode(colPins[i], INPUT_PULLUP);
  }

  lcd.print("System Ready");
}

void loop() {

  char key = scanKeypad();

  if(key){

    // Print to Serial
    Serial.print("Pressed: ");
    Serial.println(key);

    // Show on LCD
    lcd.clear();
    lcd.print("Key: ");
    lcd.print(key);

    // Beep
    digitalWrite(BUZZER, HIGH);
    delay(100);
    digitalWrite(BUZZER, LOW);

    // If A pressed → Move servo
    if(key == 'A'){
      moveServo();
    }
  }
}

char scanKeypad(){
  for(int row=0; row<4; row++){
    digitalWrite(rowPins[row], LOW);

    for(int col=0; col<4; col++){
      if(digitalRead(colPins[col]) == LOW){
        delay(200);
        digitalWrite(rowPins[row], HIGH);
        return keys[row][col];
      }
    }

    digitalWrite(rowPins[row], HIGH);
  }
  return 0;
}

// Simple manual servo control (no library)
void servoPulse(int microseconds){
  digitalWrite(SERVO_PIN, HIGH);
  delayMicroseconds(microseconds);
  digitalWrite(SERVO_PIN, LOW);
  delay(20);
}

void moveServo(){

  // Move to 0°
  for(int i=0;i<40;i++)
    servoPulse(500);

  delay(300);

  // Move to 180°
  for(int i=0;i<40;i++)
    servoPulse(2500);

  delay(300);

  // Back to 90°
  for(int i=0;i<40;i++)
    servoPulse(1500);
}