Orners CornerW3JKO · BENCH NOTES
Home/Software & Applications
2026Software & Applications

NIST-Synced Desk Clock

A Raspberry Pi fullscreen clock showing local time and UTC, locked to the NIST Internet Time Service — with a complete build guide written for first-time Pi users.

This is a desk clock built from a Raspberry Pi 4, the official 7″ touchscreen and a SmartiPi Touch Pro case. It shows local time in green and UTC in red, each with the date, and keeps itself locked to the NIST time servers (time.nist.gov) over Wi-Fi, typically to within a few thousandths of a second.

A status line along the bottom shows which NIST server the clock is locked to and how far off it is, so you always know the time on the screen can be trusted. It turns green once the clock is synced, and stays red after power-up until NIST has been reached.

Clock screen showing New York time in green, UTC in red and a NIST sync status line
Fig 1The clock screen layout on the 800×480 display

Features

  • Local time and UTC at the same time, large enough to read across the room.
  • Synced to NIST with chrony, polling no more often than NIST asks (never faster than once every 4 seconds).
  • Works in any time zone in the world: the clock uses the Pi’s own time zone setting, and daylight saving changes happen automatically.
  • Colors, 12/24-hour format and labels are easy to change at the top of the program.
  • Comes back by itself after a power cut, and reconnects to Wi-Fi without any help.

What you need

The original build uses these parts from Adafruit, plus a power supply, a microSD card and a USB keyboard and mouse for setup:

  • Raspberry Pi 4 Model B, 4 GB (Adafruit 4296) — 2 GB is plenty
  • Official Raspberry Pi 7″ Touchscreen Display (Adafruit 2718)
  • SmartiPi Touch Pro case for the Pi and official 7″ display (Adafruit 4951)

Other models: The Raspberry Pi 5, Pi 3, Pi 400/500 and Zero 2 W also work, as do HDMI monitors and the newer Touch Display 2. Appendix D of the build guide lists exactly which parts and steps change for each.

Building it

No Raspberry Pi or Linux experience is needed. The build guide walks through everything step by step: writing the microSD card, first power-up, copying the files over and running a one-step installer that sets up the NIST time sync, auto-start, Wi-Fi reconnects and screen settings. Allow about an hour, much of it waiting on downloads. Physical assembly follows the instructions that come with the case and display.

The guide also covers troubleshooting (Wi-Fi that won’t reconnect, weak signal, no NIST sync), setting the time zone, customizing the display, and using a USB Wi-Fi adapter if the clock sits far from the router.

Files