RAMPS 1.4 MArlin 2.0.9.2 + BTT TMC2208 UART - TMC Connection Error

I have a Ramps 1.4 board that I am trying to use with BigTreeTech's TMC2208 (v3.0) in UART mode with Marlin 2.0.9.2. I was able to get the motors moving correctly with A4988s, as well as TMC2208s in standalone mode.

I then attempted to connect the driver to the Ramps board via UART using the method described in the following instructable, however I consistently get a "TMC Connection Error". M122 confirms that the pins are all low (see below readout) - Please note that I have reverted the x-axis to standalone mode. The extruder driver in the left of the frame has 'extensions on the pins as as attempt to bypass the UART pin on the bottom side of the board. My Y-cables measure properly as far as I can tell, both in terms of continuity and resistance.

[www.instructables.com]

M122 readout:

I am using pin 4 (from the enable pin) on the TMC2208 as the UART pin, based on BTT's schematic, and the jumper that was soldered. Please see attached picture of the connection at the Ramps Aux serial pins. The yellow cables are the Tx pins with the 1K resistor.

I may have connected the board to 5V via USB first before 12V, which I read could possible 'damage' the driver, but the drivers still work in standalone mode. [learn.watterott.com]

I have attached my config and configuration_adv files. I am using the default pins from pins_RAMPS.h

Thanks in advance. Please let me know if additional information is required.

Bad picture.. cannot see anything

You need 12v first for TMC's to work correctly.

One thing to check is some particularly nasty ramps come with pcb traces under the micro stepping pins, so even if you remove the jumpers they are still connected.
Check they are really disconnected with a multimeter.

Edited 1 time(s). Last edit at 12/21/2021 09:13PM by Dust.

Quote
Dust
Bad picture.. cannot see anything

Apologies, I thought that the Rx and Tx pin connections on the Ramps were a likely source of error, as opposed to the rest of the board.

Quote
Dust
One thing to check is some particularly nasty ramps come pcb traces under the micro stepping pins, so even if you remove the jumpers they are still connected.
Check they are really disconnected with a multimeter.

I checked the continuity on the microstep/jumper pins, and they are all connected to their adjacent pin even without the jumper installed. I never would have thought to check that, but I see that the wiki does have a line specifically addressing this issue. Will these permanent connections damage the drivers if I try to use UART?

I have another board that does not have any continuity between the jumper pins - I will try that board (with 12 V) and advise.

Thanks

I don't know if that would damage the stepper driver or not.

Update: I swapped out the RAMPS board with the permanent continuity across the jumper pins, and instead used a RAMPS board with properly isolated jumper/micro-step pins (but without any jumpers). UART appears to work for all axes (no issues according to M122), and the movement appears to be OK (only X-axis was tested).

The drivers seem to be undamaged by the 'permanent jumpers' from the previous board, so the only apparent side effect of the jumpers seems to be a lack of UART capability.

Thank you Dust! I never would have thought to check the continuity of the jumper pins. I should be able to get my printer back up and running by this weekend. Hopefully this helps someone else in the future.

Cheers.