Raspberry Pi 4B
The printer is mainly controlled using a Raspberry Pi 4B computer running Raspberry Pi OS. On startup, the Pi should launch its own WiFi network that can be connected to with a laptop. The Pi is responsible for running Klipper and Mainsail, and is connected to the BTT Octopus board using a standard USB C cable.
There is a script running that enables GPIO pins 3(?) and 4(?) to act as a power switch when shorted. See this page for more info concerning the power button and other software.