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.

Power Button / Indicator LED

There is a script running that enables GPIO pin 3 to act as a power switch when connected to ground. See this page for more info, but in short, there is a momentary push button connected to GPIO 3 and GND which will shutdown the Pi when pressed.

According to this forum post, placing an LED across the TxD pin (GPIO 14) and GND will behave as a power indicator LED, lighting up when the Pi is on and turning off when it is safe to remove power.