#include <Keypad.h>

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

Keypad teclado = Keypad(makeKeymap(keys),pinesFilas, pinesColumnas, FILAS, COLUMNAS);

char TECLA;
char CLAVE[7];
char CLAVE_MAESTRA[7]="123456";
byte INDICE = 0;


void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  TECLA = teclado.getKey();
  if (TECLA){
    CLAVE[INDICE]=TECLA;
    INDICE++;
    Serial.print(TECLA);
  }
  if (INDICE==6){
    if(!strcmp(CLAVE, CLAVE_MAESTRA))
     Serial.println(" Correcta");
    else
     Serial.println(" Incorrecta");
    INDICE=0;
  }

}