Raspberry Pi Zero W was used for this multi selector.
I bought the RPi Zero W with the pin header already soldered to it
This is the case I am using for it:
You will also need a 8GB microSD card (I recommend Sandisk)
Here is the Raspberry Pi image you will need to load to the RPi. Just unzip it and load the img file using Win32DiskImager
Sega16-Pi Raspberry Pi Image
The pi user is: pi
The pi password is: segamulti
Here are the RPi connections that will be used and connected to the Sega16-Pi mult selector pcb
Pins 1,3,5 are used for the OLED display
Pins 11,13,15 are used for the UP, DOWN and SELECT buttons
Pins 8 and 10 are used to send and receive data from the Atmega328 chip
Pins 12,16,18 and 32 are used to program the Atmega from the Raspberry Pi
Connect a USB to microUSB cable from the multi selector to your RPi in order to power everything from one place
You also need to make a connection from the Sega16 pcb to the VCC, GND and RST pins on the multi selector
Red is VCC (5v)
Black is GND
White is RST