#include <Keypad.h>
#include <LiquidCrystal_I2C.h>
#include <LCD_I2C.h>
#include <Wire.h>

unsigned long t0, t1 = 0, espera = 1000;

LCD_I2C lcd(0x27, 16, 2);

const uint8_t ROWS = 4;
const uint8_t COLS = 4;
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

uint8_t colPins[COLS] = {5,4,3,2};
uint8_t rowPins[ROWS] = {9,8,7,6};

Keypad keypad = Keypad(makeKeymap (keys), rowPins, colPins, ROWS, COLS);
void setup() {
  lcd.begin();
  lcd.backlight();
}

void loop() {
 char key = keypad.getKey();
 if (key != NO_KEY){
    lcd.print(key);
 }
 if (key =='D'){
    lcd.clear();
    t0 = millis();
    lcd.print("Limpia Pantala");
    if (t0-t1 >= espera){
      t1 = t0;
      lcd.clear();
    }
 }
}