digital clock easy to build 

rtc: [https://www.laskakit.cz/arduino-rtc-hodiny-realneho-casu-ds3231-at24c32/](https://www.laskakit.cz/arduino-rtc-hodiny-realneho-casu-ds3231-at24c32/)

code:

#include <Wire.h>

#include <RTClib.h>

#include <TM1637Display.h>

#define CLK 2

#define DIO 3

bool alarmDone = false;

RTC_DS3231 rtc;

TM1637Display display(CLK, DIO);

void setup() {

  pinMode(11, OUTPUT);

  pinMode(4, INPUT_PULLUP);

  Wire.begin();

  rtc.begin();

  display.setBrightness(0x0f); // Jas 0-15

  // time set

  //rtc.adjust(DateTime(2025, 6, 11, 16, 29, 0)); // 11. 6. 2025 14:30:00

}

void loop() {

  if (digitalRead(4) == HIGH) {

    display.clear();

  } else {

    DateTime now = rtc.now();

    int hours = now.hour();

    int minutes = now.minute();

    bool noc = (hours >= 20 || hours < 6);

  if (noc) {

    display.setBrightness(1);  //night brightnes

  } else {

    display.setBrightness(15);  //day brightnes

  }

    display.showNumberDecEx(hours * 100 + minutes, 0b11100000, true);

    delay(100);

  if (hours == 7 && minutes == 0) {

      analogWrite(11, 250);

      delay(70);

      analogWrite(11, 0);

      delay(100);

    } else {

      analogWrite(11, 0); // alarm

    }

  }

}