A One LED Clock

Esoteric clocks are something of a staple among hardware hacker projects. If it can be made to tell the time correctly, even if only twice a day, the chances are someone’s made a clock from it. And if the only person who can read that clock is its creator, so much the better. Universal accessibility is not always a virtue in the world of unusual timepieces.


[Setvir] writes to us with details of his One LED Clock. It’s an Arduino Pro Micro with an RTC module and an LED. That’s all, time is communicated to the world through LED flashes. You might expect therefore that it would use Morse Code, but he’s come up with his own timing communication scheme which does have some merit. Long flashes cover a quarter of the clock face, while short flashes cover individual hours or five-minute segments. He goes into detail on the project page and we can see that once you are used to the scheme it has an elegance to it, but it certainly ticks the essential unreadable-to-the-uninitiated box for an esoteric clock.

We like it though for its simplicity and for the flashing scheme, which once explained is both efficient and easy to read. If you would like to have a go yourself he’s published his code, so go forth and cover the world with baffling single-LED timepieces!

We’ve featured a few minimalist LED clocks before, at least one with a minimal face, and another single-LED offering. But that one used a bi-colour LED, so [Setvir] takes the minimalism crown.

18 thoughts on “A One LED Clock

  1. My daughter used a similar trick to indicate one’s position in a menu tree, except she had an RGB LED so each bit position in a number had a colour assigned to it. She had it wait for off bits but this was not really needed. BCD with stop and start colours is very easy to implement too, just make sure to keep sequential colours as different as possible.

  2. This just gave me an idea : a 3D model of a resistor, with the color strips replaced with neopixels. 4 strips. Color is the same than resistor color code. Voila! you got a resistor clock (some colors may be hard to render and read, experience is not guaranteed)

          1. We could toss around ideas here to help give people a jump-start.

            e.g. You could represent the time as a musical chord so that the chime was shorter. Assuming you just want to indicate HH:MM that would be 4 notes to play at the same time to indicate the digits, encoded in BCD with long and short for 1 and 0. With the last digit stretched for effect, Dah dee dah daaaah!

            To earn Nerdlord status you’d need to let the user select the key for the chord, by whistling an example. :-)

  3. Getting a *protocol* to work for you is the fun part. What’s nice about this is that you can read the clock with your eyes closed. Since you are working with one pixel, if you can see only light v dark it will work. You could make it wearable with a little vibrator motor and cause yourself to suddenly have an uncanny sense of time.

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