A man with a watch knows what time it is. Mentioned in this video (some links are affiliate links): - Excuse me, what precise time is it? https://media.ccc.de/v/39c3-excuse-me-what-precise-time-is-it - PTP Wallclock open source project: https://github.com/Gemini2350/ptp-wallclock - My blog post on the setup: https://www.jeffgeerling.com/blog/2026/ptp-wall-clock-impractical-too-precise/ - Geerling Engineering video on the Blues game and PTP: https://www.youtube.com/watch?v=8Ar4wmA4ujM - Video on the Pico GPS mini rack clock: https://www.youtube.com/watch?v=E5qA4fgdS28 - Video on the Mitxela Precision Clock Mk IV: https://www.youtube.com/watch?v=aBDgD032DEI Parts needed for the build: - Raspberry Pi 4 B: https://www.raspberrypi.com/products/raspberry-pi-4-model-b/ - Adafruit RGB Matrix HAT: https://www.adafruit.com/product/2345 - (2x) Waveshare 64x32 LED RGB Matrix Panel: https://www.waveshare.com/RGB-Matrix-P3-64x32.htm - 3D Printable joining bracket: https://www.printables.com/model/1624778-ptp-wall-clock-bracket-waveshare-rgb-matrix-connec/collections - DC 5V 4A power supply: https://amzn.to/3P1I8XG - 32GB microSD card: https://amzn.to/3NhlGJE Support me on Patreon: https://www.patreon.com/geerlingguy Sponsor me on GitHub: https://github.com/sponsors/geerlingguy Merch: https://www.redshirtjeff.com 2nd Channel: https://www.youtube.com/@GeerlingEngineering 3rd Channel: https://www.youtube.com/@Level2Jeff Contents: 00:00 - Excuse me, what time is it? 02:01 - Parts required to build a PTP clock 03:14 - Building a precise clock 04:32 - Software for controlling the matrix 05:26 - It works! 06:06 - Keeping it together 07:17 - The problem... 09:04 - It's a timing bug 11:36 - Back in the box