#include <Wire.h>
#include <RTClib.h>
#include <LiquidCrystal_I2C.h>

RTC_DS3231 rtc;
LiquidCrystal_I2C lcd(0x27, 16, 2);
unsigned long previousMillis = 0;
unsigned long interval = 1000;

void setup() {
  Serial.begin(115200);
  Wire.begin();
  lcd.init();
  lcd.backlight();

  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (1);
  }

  if (! rtc.begin()) {
    Serial.println("RTC is NOT running!");
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
  }
}

void loop() {
  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis;

    DateTime now = rtc.now();
    lcd.setCursor(0,0);
    lcd.print(now.hour());
    lcd.print(":");
    lcd.print(now.minute());
    lcd.print(":");
    lcd.print(now.second());
    lcd.setCursor(0,1);
    lcd.print(now.day());
    lcd.print("/");
    lcd.print(now.month());
    lcd.print("/");
    lcd.print(now.year());

    if (now.minute() == 0) {
      tone(8, 1000, 500);
      delay(500);
      noTone(8);
      delay(500);
    } else if (now.minute() == 30) {
      tone(8, 2000, 500);
      delay(500);
      noTone(8);
      delay(500);
    }
  }
}