I just went to pick up my LiFePO4wered/Pi panels at Colorado Tech Shop, here's what 250 little boards in hand looks like:

Now it's up to me to start building some up!

Meanwhile, I've been hard at work on the firmware. I discovered that due to some recent changes, the off current had increased from 8 to ~50 uA. Not good! I found the problem and fixed it. In the process, I also implemented a system tick prescaler, since the system was running the touch detection and ADC conversions more often than necessary. Result: average off current is now reduced to 4-5 uA! :)

I also worked on the wake up timer calibration. At first my idea had been that I could make the user read a calibration value register, which would allow them to calculate a wake up time to set, based on that value. In the process of writing the code, it became obvious that I could just as well handle all the calibration in the firmware and just allow the user to set the number of minutes. Much better! Wake up accuracy has improved from a factor of 10 worst case to +/-10-15%.

At the moment I'm working on the Pi-side software, to allow it to deal correctly with multiple register set versions so earlier prototypes keep working and future firmware changes won't cause issues with older boards.