My project to monitor & control a grandfather clock built for me by my father. It's been running for many years and is starting to show wear in the timekeeping mechanism and the chimes.
I use an arduino with an electromagnet to influence the clock to maintain the correct time within less than a second relative to a Adafruit Ultimate GPS Breakout GPS. Typically, the clock drifts within a 100 millisecond range over weeks.
Picture of clock
https://www.flickr.com/photos/88117211@N00/33824316033/
Picture of controller
https://www.flickr.com/photos/88117211@N00/51009642002/
Statistics graph:
https://www.flickr.com/photos/88117211@N00/51009567372/
Removed apt-get of arduino and downloaded version from arduino people. This lets me compile and upload on the actual rp1. I am happy about that!
Goto https://www.arduino.cc/en/software and download the ARM version, maybe
https://downloads.arduino.cc/arduino-nightly-linuxarm.tar.xz
Added code to automatically update GPS seconds by one if ann error is detected.
Also installed git on HP4. Context menu for the q:\ folder has an "open git bash here" command then, in MINGW64 window, enter ./pushit
Note to self: remember to pushit from dell2 (or HP4) in \\rp1\pi\Arduino\sketchbook\gdsPendulum folder, not from rp1.