Precision Clock Mk IV

Summary

Precision Clock Mk IV31 May 2025Progress: Complete This page is about the development of the Precision Clock Mk IV. VIDEO I designed this clock years ago, with the intention to incorporate every feature request I ever received for the previous precision clock. However, during the pandemic there was a chip shortage, where these STM32 parts became impossible to acquire. Given the amount of work I put into the clock, I didn't have the heart to redesign it using different parts, so instead I put it aside, and never got around to releasing it – until now. Contents Summary The specifications for the clock were as follows: Millisecond precision, with no perceptible jitter Display clearly, without flicker, when filmed at very high framerates (20,000fps or more). The brightness should still automatically adjust, of course, and without the use of PWM Timezone and offset should be determined automatically from the GPS coordinates, no customisation or user interaction needed Keep good time while turned off (a quartz crystal and watch battery) Easy antenna upgrades (an SMA connector instead of a fiddly u.FL) Easy repairs (all parts on the back are surface mount, so every component is accessible without having to unsolder digits) The precision should reflect accuracy. So if the GPS fix is lost and the time starts to drift, digits should progressively disappear from the end Multiple display modes, such as ISO-ordinal. More modes should be easy to enable and easy to expand in future (this means writing in C, not assembly!) Easy firmware updates. It's paramount that updating the timezone database, and the clock firmware, should be as simple as copying and pasting a file. Another request I often had was to split the display onto two lines, as it's very wide otherwise. But some people love the very wide design, for the ISO timestamp aesthetic. There was only one way to please everyone: add an articulated joint, so the clock can transform from one to the other. This substantially compl...