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Arduino LED clock with the DS3231 RTC clock and contrlled by a rotary encoder.

Finally I was able to complete the Arduino LED clock with DS 3231 RTC module. This is checked few days and I found the clock is working accurately. It is expected that there is no time changes during the operations as I have to check it about one moth to identify the errors.

This arduino clock has 6 digits, 2 for hours, 2 for minutes and the balance 2 for seconds. You can use this clock as 24h mode or 12 hour mode. Instead of midnight 12, the clock will show 0.OperationMain part of this project is atmega 328 programming IC and it is connected RTC module DS 3231. The RTC module has a battery cell and it can be sored the current time.

Therefore, even the device power is down, once the power came the correct time will be displayed. Time display using DIY SSDs with LED bulbs. those are powered by NPN transistors (D400). In order to display the time multiplex method is used.


Just the programme is uploaded, the computer time will be displayed.

1. Press one time the rotary encoder to change the minutes : you can up and down the minutes by rotating the rotary encoder.

2. Press one more time the rotary encoder to change the Hours: you can up and down the hours by rotating the rotary encoder. after the 12 noon, it will show 13, 14, 15 etc up to 23 and the 24 will be displayed as 0.

3.Press again to save the time. As press the 3rd time, the seconds will be “00” with saving the time.

24/12 hour mode

** You can change the mode from 24 hour to 12 hour by pressing the button switch.”

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