I recently purchased an i3 mk3.
These are running notes related to setup/initial observations etc.
I. Protopasta HTPLA filaments jam.
The Einsy board has a “RPi Port” designed to allow the i3 mk3 to communicate with a Raspberry Pi Zero W via SPI and Serial.
Prusa semi-officially supports octoprint/prusa print on a Pi Zero W.
You can of course use any Pi that can run octoprint. You can even use the hardware pins. But, note, that all Pis do hardware serial a bit differently. Specifically, the UART pins can be shared with bluetooth on some boards etc.
Look up how to “enable hardware serial for **insert your pi model here**”
However, I decided to use a USB connection with stock Octoprint on a RPi 4, and I am very happy. I don’t see the need to hardwire the pins. Frankly, the performance of hardware UART across the different Pi models is all over the place.
There is a bit of FUD around on RPi4s and Octoprint — I haven’t encountered issues.
The interactions between octoprint via USB and the i3 Einsy board are fine. It just offers an alternative way to use the printer. I still feel like I have my stock printer.
Julia Ebert has some excellent notes on setting any Pi/Octoprint with the i3: