Document pinout

[probonopd]

Please document the pinout of all of the headers.

MiniRambo1.3a

[urbaniak]

That's the only one schema I've found describing the p3 (yellow) connector, looks great!

Got one question - does the RX/TX pins there are the same serial interface as the one available via usb? I want to connect octopi on raspberry (zero maybe) directly to the board (not via usb, which causes board reset when connecting).

[probonopd]

No, these RX/TX pins on connector P3 (SERIAL_PORT 2) are not the same pins as the one connected to USB. According to the Ultimachine technical support, the RX/TX connected to USB (SERIAL_PORT 0) is only available as test points on the back side of the board. Bummer.