#include <Keypad.h>
#define ROW_NUM 4 // 4 LINHAS
#define COLUMN_NUM 4 // 4 LINHAS

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

byte pin_rows[ROW_NUM]   = {21,19,18,5}; // R1, R2, R3,R4
byte pin_column[COLUMN_NUM] = {17,16,4,2}; // C1, C2, C3,C4

Keypad keypad = Keypad( makeKeymap(keys), pin_rows, pin_column, ROW_NUM,COLUMN_NUM);


const String password = "1234"; // SENHA
String input_password;

void setup() {
  Serial.begin(115200);
 input_password.reserve(32);  // até 33 caracteres de input

}

void loop() {
  char key = keypad.getKey();
 if (key) { 
   Serial.println (key);
   if (key == '*') {
     input_password = ""; // RESET SENHA
   } else if (key == '#') {
     if (password == input_password) {
       Serial.println("Senha Correta - ACESSO PERMITIDO");
     } else { Serial.println("Senha Errada - ACESSO BLOQUEADO");}

     input_password = ""; // RESETA A SENHA 
   } else {




   }
 }
}