This Tide and Moon Clock Lets You Keep an Eye on the Seas and Sky — But Not The Time

Maker PJ Dines has turned an old brass carriage clock into a lunar-centric moon and tide clock, courtesy of a Raspberry Pi Pico W running MicroPython — with the only drawback being that it no longer tells you the time.

"Want a clock that can't tell time but instead uses the current time to calculate the lunar phase and an incredibly specific oceanographic prediction for a tiny subset of the UK coastline," Dines asks, rhetorically, of their latest project. "THEN HAVE I GOT THE CLOCK FOR YOU. Presenting the worlds first Tide and Moon clock."

The chassis for the build is taken from an old carriage clock, with its innards removed and a suitably chunky switch added to the side for manual power control. Inside is a Raspberry Pi Pico W development board, running MicroPython on its RP2040 microcontroller, linked to a real-time clock and a 3.7" ePaper display — plus a charge controller for a small lithium polymer battery, easily good for keeping the clock ticking even if you don't use the manual power switch on its side.

Normally, those internals would then be used to pull the current time down from a Network Time Protocol (NTP) server, write it to the memory of the real-time clock, and display it on the ePaper panel — refreshing once every minute, rather than second, to take advantage of the fact ePaper only requires power when changing states. Dines' clock, though, doesn't tell the time — but the tides.

Once a day, the clock decompresses one of 24 images of the moon to indicate its current phase then either connects to the network and pulls down high and low tide times for a user-selectable location — Whitstable in the UK, in this case — or from a locally-stored list.

"Tide prediction is extremely hard. I mean like PhD-level complicated," Dines explains. "I have included in my code both the functionality to get the tide data from a website and the ability to read the tide information from a set of long term predictions. This allows my clock to work when not connected to the Wi-Fi as it can calculate both the tide times based on the prediction data and the lunar phase from the RTC unit in the clock."

A full write-up is available on Instructables, while source code can be found on GitHub under an unspecified open source license.