NIXIE Clock: Basics
I finally got the code out to talk to the RTC over I²C and amazingly it even worked first time. The real time clock has been set and has a battery to keep time, so whenever I plug in mains power the two nixies light up to show hours and minutes. I've only connected two for the moment, but many more can be connected - year, month, date, hour, minutes and seconds are all available.
Adjusting the time is also supported using the buttons on the control board, which are pretty easy - hold down the field to change (year, hour, etc) and press (or hold) either + or - to change (or keep changing) it.
All that's left now is tidying up the code, connecting all 12 NIXIEs, maybe writing the code to turn it off overnight and cycle the NIXIEs to prevent cathode poisoning, then see where I'm at...