#include <Keypad.h>
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};
byte rowPins[ROWS]={14,27,26,25};
byte colPins[COLS]={33,32,23,22};
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
String correctPin="A0620#";
String enteredPin="";
int relay = 21;

void setup() {
  Serial.begin(115200);
  pinMode(relay,OUTPUT);
  
}

void loop() {
 
  char key = keypad.getKey();
  if(key){
    Serial.print("Key Pressed: ");
    Serial.print(key);
    if((key >= '0' && key <= '9')||
    (key >= 'A' && key <= 'D')||
    key == '*'|| key == '#'){
      enteredPin += key;

    }
    if(enteredPin.length()==6){
      if(enteredPin==correctPin){
        Serial.println("ACCESS GRANTED");
        digitalWrite(relay,HIGH);
      }
      else{
        Serial.println("ACCESS DENIED");
        digitalWrite(relay,LOW);
      }
      enteredPin = "";
    }
  }
}