What pins do I use for UART control on a RUMBA board for tmc2208? I have been looking in the Marlin firmware for about an hour or two now to find what pins I should use for UART for my tmc2208 drivers and I have come up with nothing. Does anyone know what they are or how to assign them? BTW, I am using the regular version of the RUMBA board not the RUMBA+ version. For somereason i didn't put that i want to control my stepper motor drivers through uart they are tmc2208

The RUMBA schematic is available on the RUMBA wiki.

> ![RUMBA schematic]( "RUMBA schematic")

From the schematic, I see that UART3 (with +5V logic levels, not RS232) is presented on the EXP3 connector. I don't know if Marlin firmware can be controlled through a UART other than UART0, which is converted to USB through an FDDI chip. The Arduino bootloader is not expecting another UART, so you may still need to program it through the USB port (and UART0).