Integrated TMC2208 UART mode wiring

Greetings everyone,

I am working on a new board layout similar to RUMBA but with integrated TMC2208.

I am looking for a schematic that includes UART mode connections between the drivers and the atmega2560 IC.

I stumbled on some articles considering this matter in a different way which is converting from the standard legacy mode to UART mode but I didn't help but notice when I looked into pin assignments that tx and rx pins are defined or mapped to regular digital and analog pins which struck me as ODD. Can anybody explain this matter?

I am thinking of connecting all the 4 motors with UART mode (if possible) for optimum performance directly without the need of jumpers or any external modification ( I know it is not recommended for flexibility use but I want to know how to do this first, then I will work on flexibility later).

Thank you !

regular IO pins, yes because they are using software serial. (also note that not all pins can do software serial... see [www.arduino.cc] )

Using real hardware UART's would be a waste, and there are not enough of them (4 on a mega2560 and one is connected to usb/serial for the usb port)

Re analog, they where probably just using those names, but using the digital pins, a confusing practice.

Edited 1 time(s). Last edit at 02/03/2020 09:58AM by Dust.

Thank you for clarifying this
I've read the there's a downside in using software serial which is you cannot use multiple pins in the same instant. Does this affect negatively on the performance of 3D printing?
There is another library called AltSoftSerial which tackles this problem. did anybody use it for simultaneous serial communication?
What about unconnected pins if I use the UART communication using one PDN pin in TMC2208 ICs ?

Quote
xdarko
I've read the there's a downside in using software serial which is you cannot use multiple pins in the same instant. Does this affect negatively on the performance of 3D printing?

As long as you don't enable MONITOR_DRIVER_STATUS (current Marlin 2.0.x disallows setting MONITOR_DRIVER_STATUS on AVR processors) there should be no effect on the performance. The UART is only used to configure the drivers - once the print has started the UART is idle.

Thanks!
I will wire all X,Y,Z to UART mode that should be most efficient. As for the extruder I will use standalone OTP mode for spreadcycle enabling and get most of torque and velocity.