void updateLCD() {
  lcd.setCursor(4, 0);
  if (hour < 10) {
    lcd.print(F("0"));
  }
  lcd.print(hour, DEC);
  lcd.setCursor(7, 0);
  if (minute < 10) {
    lcd.print(F("0"));
  }
  lcd.print(minute, DEC);
  lcd.setCursor(10, 0);
  if (second < 10) {
    lcd.print(F("0"));
  }
  lcd.print(second, DEC);
}