#include <LiquidCrystal_I2C.h>
#include <Wire.h>
#include <Keypad.h>
LiquidCrystal_I2C lcd(0x27,16,2);

const byte filas = 4;
const byte columnas = 4;
String suma = "";
byte pinesfilas[] = {16,17,18,19};
byte pinescolumnas[] = {6,7,8,9};
char teclas [4][4]= {{'1','2','3','A'},
{'4','5','6','B'},
{'7','8','9','C'},
{'*','0','#','D'}};
int led=13;
Keypad teclado = Keypad (makeKeymap(teclas),pinesfilas,pinescolumnas,filas,columnas);

void setup()
{
   lcd.init();
  lcd.backlight();
  lcd.begin(16, 2);
  lcd.print("     TECLA    ");
  
}

void loop()
{
  char tecla_presionar = teclado.getKey();
  if (tecla_presionar){
    if (tecla_presionar == '#'){
      suma = "";
      tecla_presionar = ' ';
    }
    suma=suma+tecla_presionar;
    
  lcd.clear();
 lcd.setCursor (0,0);
    if (tecla_presionar == '1' ){
      digitalWrite (led, 1);}
    else {
      digitalWrite (led,0);}
      
  lcd.print (suma);
   delay (50);
     
    
}
}