A Neat E-Paper Digit Clock (or Four)

[sprite_tm] had a problem. He needed a clock for the living room, but didn’t want to just buy something off the shelf. In his own words, “It’s an opportunity for …read more

May 3, 2025 - 06:10

[sprite_tm] had a problem. He needed a clock for the living room, but didn’t want to just buy something off the shelf. In his own words, “It’s an opportunity for a cool project that I’d rather not let go to waste.” Thus started a project to build a fun e-paper digit clock!

There were several goals for the build from the outset. It had to be battery driven, large enough to be easily readable, and readily visible both during the day and in low-light conditions. It also needed to be low maintenance, and “interesting,” as [sprite_tm] put it. This drove the design towards an e-paper solution. However, large e-paper displays can be a bit pricy. That spawned a creative idea—why not grab four smaller displays and make a clock with separate individual digits instead?

The build description covers the full design, from the ESP32 at the heart of things to odd brownout issues and the old-school Nokia batteries providing the juice. Indeed, [sprite_tm] even went the creative route, making each individual digit of the clock operate largely independently. Each has its own battery, microcontroller, and display. To save battery life, only the hours digit has to spend energy syncing with an NTP time server, and it uses the short-range ESPNow protocol to send time updates to the other digits.

It’s an unconventional clock, to be sure; you could even consider it four clocks in one. Ultimately, though, that’s what we like in a timepiece here at Hackaday. Meanwhile, if you’ve come up with a fun and innovative way to tell time, be sure to let us know on the tipsline!

[Thanks to Maarten Tromp for the tip!]