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!