I plan to have some working code (based on Chris's work) and a working controller by this weekend if possible.

I've been working through power requirements for the new controller. The air pump i have (https://www.ebay.com/itm/263145594968?) runs on 5v but also runs (slower) on 3.3v. I'm currently running the solenoid on 3.3v, sourced from the xiao's onboard voltage regulator. I'd like to keep the parts count as low as possible and it's currently using about 150ma (screen, microcontroller, bmp280, solenoid). I think the pump will draw about 200ma which, with the other current loads, would be close to marginal for the onboard regulator, especially when powered with a 2s lifepo. I may run it from receiver voltage.

Above all, the controller reliability is paramount. I'd rather not add an external regulator if I can avoid it. I may power the solenoid from the receiver battery directly if required.

Chris, I have several questions for you...
1. Are you using 5v air pumps or did you order something that runs on higher or lower voltage?
2. Are you powering your pump through a regulator or are you using your receiver battery?
3. What tank pressure are you generating at full throttle? (Or if you have any numbers, bert, feel free to share)

I haven't measured the pressure my pump generates. I do have a calibrated digital manometer that can measure down to a few hundredths of an inch water column so I can match your numbers. My pump generates a bunch of pressure on 5v but I'm not sure how well it'll throttle down and I'm not sure what it will generate at 3v so I'll be dusting off my manometer soon.

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