#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

int counter = 20;
int pinBuzzer = 5;

void setup() {
  lcd.init();
  lcd.backlight();
  pinMode(pinBuzzer, OUTPUT);
}

void loop() {
  if (counter >= 0) {
    lcd.setCursor(0, 0);
    lcd.print("Counter: ");
    lcd.print(counter);
    lcd.print("  ");
    
    if (counter > 0 && counter % 4 == 0) {
      tone(pinBuzzer, 1000, 500);
    }
    
    counter--; 
    delay(1000); 
  } else {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Mengulang...");
    delay(1000); 
    counter = 20;
    lcd.clear();
  }
}