ATtiny84 Powered Minimalist LED Clock

LED Clock ATtiny84

We feature a lot of clock builds on HaD, and the reason is that they are cool. Even simple ones are cool. Not everyone can say they built a clock. [Chris] took a ride on the DIY Clock train and came up with this LED-based clock that is controlled by an ATtiny84 chip.

The clock has 24 LEDs total, 1 for each hour and 1 for every 5 minute increment. The 24 LEDs are arranged in 2 concentric rings. To display the hour, both LEDs at the same angle are lit up. To show the minutes, just the inner LED is lit. The main image above shows 6:40.

If you are familiar with the ATtiny84 you know that it only has 12 in/out pins, which is significantly less than the amount of LEDs that need controlling. [Chris] decided to use some 74HC595 shift registers to increase the IO pins on the ATtiny. The entire build is installed on a protoboard with quite a bit of point-to-point wiring. A simple tinted plastic case finishes the project and gives it a modern look.

[Chris] made the code for his clock available in case any readers are interested in making one.

LED Clock ATtiny84


  1. Figureitout says:

    You can actually get pretty lost thinking about clocks and time…Especially when thinking about a “clock signal” and where the original control comes from.

  2. nya says:

    Is it IP68? What happens when you submerge this clock in urine?

  3. Andrew says:

    Charlieplexing, FTW?

  4. I like the case made from sheet plastic. I’m curious what the specs are for it – hdpe?
    For a minimalist digital clock, I was impressed by this design:

  5. Rich says:

    I would have made two leds represent minutes (like a long hand) and one inner led represent the hour (like a short hand). Nice touch with the tinted plastic on the front.

  6. busygreg says:

    It’s not full-featured, it has no buttons to set it.. but it’s way better than my clock, because I haven’t built it yet.

    Excellent work, I am inspired to finish more projects even if they don’t have the feature set I dream of.

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