Led Matrix Arduino Clock




This a week-end project.

Six 8x8 led matrix, Arduino nano and Real Time Clock.

It just gives time. No fancy alarm or display mode even though I wanted to do so in the begining.

The RTC clock is very precise so I don't need buttons to adjust time. Twice a year, just need to reupload the program to adjust time with DST.


Video available here : https://www.youtube.com/watch?v=yoBDhjfy_UA

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Hardware

6 led matrix with integrated MAX7219

Arduino Nano (chinese version on ebay)

LM7805 circuit to make a 5V power distribution for leds, Arduino and RTC

Real Time Clock RTC DS3231 (this model is very efficient, I have only a few second drift in 6 months.

The setup is very simple.

The Arduino is connected to the RTC through I2C (ports A4, A5 on Arduino).

The matrix are daisy-chained, so it only require 3 wires (D10, D11 and D12).

A LM7805 gets between 7,5 V to 12 v on one side and delivers 5 V on the other.

Everything is soldered on a board. A few wires on the back and we have a clean setup.

I also added a 1N4007 led to prevent polarity inversion.

Step 2: Software

The program is quite simple.

I made custom fonts in 6x9 size.

The main loop reads time in the RTC and triggers the animation for every digit if it changed.

The tircky part is to convert the 6 independent 8x8 matrix into a single 16x24 matrix adressable through xy coordinates.

I used the ledcontrol.h library to help me in this process.

The code : http://blog.ouiaremakers.com/wp-content/uploads/formidable/ClockLedMatrix16x24.ino

Step 3: The Box

Made of pine wood (22mm x 40 mm), the housing is basic.

Tainted with red wax, the finish is simple but clean.

The bottom is plywood of 2mm. All the electronic is fixed on the back plane.

Be the First to Share


    • Made with Math Contest

      Made with Math Contest
    • Multi-Discipline Contest

      Multi-Discipline Contest
    • Robotics Contest

      Robotics Contest

    8 Discussions


    2 years ago

    Thanks all for your replies.

    We change to winter time last week-end. I am lazy to open it to update the time. Therefore I am designing an automtic piece of software to manage the DST. I'll keep you posted on it.


    2 years ago

    i wil build this soon, i got everything in tripple maybe even more, but i wanna build firt the arduino watch with also the same parts but then with a WS2812B addressable ring, so the time is being displayed in colors

    and no led matrixes,

    but after that watch i wil build this also.

    i love arduino and self build clocks, i just started building them and also collecting them, (but now build and diy from sckratch) like you.

    not pre make stuff like i did first , that you slap on a couple of parts and solder it.

    but i like that stil also.


    2 years ago

    Great design! I am a starter with the Arduino so adding the wiring diagram wil be very helpfull :)


    2 years ago

    Truly elegant in its simplicity. One of the few I've considered building. Well done!

    Anirudh Ralhan

    2 years ago

    Just like the clocks at railway stations...


    2 years ago

    @Swansong : Thanks


    2 years ago

    This is a fun design :)