I Wanted a Clock That Never Needed Setting, So I Built One with a Raspberry Pi

I wanted a clock that never needed setting. Things escalated

▲ 12lee_ars2 HN discussion
I Wanted a Clock That Never Needed Setting, So I Built One with a Raspberry Pi

Frustrated by manual time adjustments on standard clocks, I decided to build a custom self-setting device using a Raspberry Pi Zero W and an Adafruit seven-segment display. To overcome my limited Python skills, I relied on an LLM to generate the code, resulting in a fully automated clock managed by a deployment pipeline and integrated with HomeKit.

It was a bit like unleashing the full power of the Death Star on a mosquito, but it definitely did the trick.
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2
  1. Frost1x

    I’ve had a Phillips “atomic” alarm clock beside my bed for 23 years that just sets based on radio signal and auto restores if the power is lost, to which it has a backup 9v battery.

    There’s a time zone setting offset slider and a DST slider. I basically touch it twice a year, maybe another if I move time zones. I’ve only had to touch it for DST (never switched time zones). Takes me conservatively 10 seconds to find and flip, so it’s taken me 460 seconds or a little under 8 minutes in the past 23 years to do time adjustments.

    While these efforts are definitely fun hobby projects, there are cheap reliable solutions out there with minimal intervention that consume the NIST radio signal for time.

    Just for anyone interested who wasn’t aware there’s some “old school” time broadcast solutions out there too besides NTP:

    https://www.nist.gov/pml/time-and-frequency-division/time-di...

  2. Animats

    It's a clock. Does it really have to have remote updating, a command line interface, an Internet connection, and HomeKit integration? That's too IoT.

    I have three La Crosse clocks that run off the NIST time signal out of Boulder, CO, and need their AA battery replaced maybe once a year. The real challenge is running such a thing on a small battery for a year.

    I once made a small clock that displayed "A LITTLE AFTER SIX" and such, changing its text every five minutes. Needed a power connection, though.

  3. sudb

    This reminded of this other clock project:

    https://mitxela.com/projects/precision_clock_mk_iv

    Also: I reckon the closest best-value watch alternative that ticks most(?) of the author's boxes is the Casio GW-M5610-1ER, so long as you are inside a radio-controlled time area.

  4. sasaf5

    "One, the path not taken, started with an Arduino or Arduino-like microcontroller. The other began with a Raspberry Pi or Pi-like computer-y thing. I went with the Pi, variously using both a Raspberry Pi Zero W and Zero 2 W."

    Ok, so instead of bumping your clock +- one hour twice a year you preferred distro upgrades?

  5. craftkiller

    Edit: I was wrong! original post below:

    > Battery-backed self-setting “atomic” clocks that get their updates via the cosmic ether have been a thing for years and get me most of the way there, but damned if I could find one with a red seven-segment display that I liked (maybe someone else’s search kung-fu is better than mine?)

    I found this with ~5 minutes of searching. I think it meets your critera: https://www.amazon.com/Sharp-Digital-Alarm-AccuSet-Automatic...

    (Regardless, cool project! I think yours still looks better than this one)

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2026-07-27