Since the manager (328pb) on this board has ADC to power (V and I) and auxiliary (V and I) inputs, as well as control over the power to the host (R-Pi zero), and the auxiliary input itself I spent a long time sorting out some state machines (I think of them as daemons) that run on the manager alongside the multi-drop bus stuff that I did for the previous shields. At times it felt like I had bitten off too much, but pieces slowly started to fit. I know it is not done, but I need to spin on some other things while I test it. The auxiliary input is for solar power mainly for charging a battery on the main power input, but it may work with other current limited sources.

The three little daemons include a day-night state machine, a battery manager (bm) state machine, and a host shutdown state machine. The bm keeps the auxiliary disabled unless day-night is in the day state, and can trip the software shutdown state as well. A lot of these ideas were tried on my other boards, but it eats up a lot of programming space and can interfere with the application, so it makes sense to move these tasks to the manager, which was underused.

I plan to layout ^2 to correct the known bugs, I do not plan to build it. I will then start work on ^3 which will replace the 328pb with an AVR128da32 and the 324pb with a AVR128da48, but I will not finish this new layout. I will fork it to replace my 328p board with a AVR128da28 in PDIP, I will skip all the current sources and level shifting to keep things as simple as possible. These new DA's have very robust electrical specs, and the PDIP is easy to replace.