Yes it is popular, maybe we should all get out more?
The PIC10F320 arrived and I banged it on some stripboard with an ICD header which also acts as the battery connector. In hindsight, I wish I'd made the stripboard long and thin rather than square, then it would fit well inside the old battery compartment.
After a couple of hours test, I noticed that although the second hand was moving, the hours and minutes weren't. Bummer. After taking the clock mechanism apart and putting it back together again, it worked fine, so I guess something hadn't quite connected to the right place.
With a bit of hacking, I managed to fit a BNC connector on the back to connect to the 1pps gpsdo signal and have drawn a diagram using LTSpice (thanks PA0PBZ)
The PIC source code is exactly the same, apart from some #pragma configs that did not exist for the new simpler chip. The 1pps signal is fed into input RA2 which can also be configured as an interrupt, so that will allow for further development, maybe the crazy clock?
The only slight issue is that if you unplug the 1pps gpsdo signal, the second hand can move occasionally as that input is floating and probably needs a pull up/down resistor to make it more stable.
As a quick test, I set the clock to the second last night and checked it this morning against:
https://www.timeanddate.com/worldclock/uk/londonAnd it was bang on. Not a severe test, but a start.
Well, that's me all done now. Thanks to everyone that posted up :-)
Cheers
Steve