#include <Keypad.h>
#include <LiquidCrystal_I2C.h>
#define row_num 4
#define col_num 4

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

byte row_pins[row_num]={19,18,5,17};
byte col_pins[col_num]={16,4,2,15};

String mypassword="1234";
String input="";

LiquidCrystal_I2C lcd(0x27,20,4);
Keypad mykeypad= Keypad(makeKeymap(keys),row_pins,col_pins,row_num,col_num);
void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  lcd.init();
  lcd.clear();
  lcd.backlight();

  lcd.setCursor(5,0);
  lcd.print("KeyPad");
  

  Serial.print("Enter the password:  ");
  delay(500);
}

void loop() {
  // put your main code here, to run repeatedly:
   char key= mykeypad.getKey();
   if(key){
      Serial.print(key);
      lcd.clear();
      lcd.setCursor(5,0);
      lcd.print(String(key));

      if(key =='#'){
        Serial.println();

        if(input.compareTo(mypassword) == 0){
          Serial.println("Access granted...");
           while(true);
        }
        else{
           Serial.println("Access denined...");
           Serial.print("Try again!...");
        }
        input="";
      }
      else if(key == '*'){
        input="";
        Serial.println();
        Serial.print("Password is cleared,enter again..");
      } 
   }
   else{
    input.concat(key);
    // Serial.print(key);
   }
}