This information is provided for information only, and shoudl be considered provisional.
(This is not finished yet)
It's probably worth creating a daughterboard that connects into the Arduino nano footprint and also allows the 40-way Raspberry Pi header connected.
This UKMarsBot v1 was designed to use 5v, however, some work has been made on running it on 3v aleady.
The Raspberry Pi Zero requires a 5v supply - which can be provided via one micro USB headers or via the 5v pins on the GPIO header.
Possible options are:
- DC-DC converter - this is probably the best option
Provide an ADC - potentially with a serial interface like I2C or SPI. Provide a 5v regulator. Convert the UKMARS I/O to 3v3. This is not overly problematic- - the http://ukmars.org site details this for other boards (like the Arduino Nano 33 BLE). Figure out how to route a PWM signal to the motors for speed control.