Hi to everybody,
sorry to pollute your forum with this question but I’ve been struggling a lot with this issue and I really don’t know where else to look for.
I have a flsun qq-s pro stock that I recently converted to klipper/octoprint, and I have to say it works amazing! However, lately, I’ve been trying to upgrade it with a sherpa extruder: I haven’t had any issue with rigid filaments, but for flexible ones the extruder seems to skip quite a few steps. Before moving to klipper I used to tune things like these through a screw in the related tmc2208 driver, but that doesn’t seem to work anymore (even the voltage I measure there turned to 12V after updating to klipper O.o I was measuring 0.8V before). In this case, instead, I thought I needed to add a [tmc2208 extruder] section in the configuration, and set the run_current property. However, that doesn’t seem to work, I keep getting the error “Unable to read tmc uart ‘extruder’ register IFCNT” as soon as I try to move the extruder: by googling, it seems like klipper doesn’t manage to speak through the uart port, but the uart pin is correct, as far as I can google about it, so I don’t really know what else to look
What could be the problem? Am I looking at the right direction, or is there a different approach to solve my issue? Thank you very much for any help you can give
Hi Eddy,
thank you very much for your answer!
I’m not sure about that pin really, I’ve just found it in the tmc2209 klipper configuration and in the marlin source code, both codes matched so I hoped I could be lucky and try to put it there :S I’m sorry, I’m a total noob in the 3d printer world and I really don’t know where to look for the proper pin. is it something I could understand just by looking at the board?
What I don’t understand is that I was actually able to tune the power of this motor, before moving to klipper even if just by moving a screw on the driver. Moreover, I just detached the driver and I didn’t even find the pads to solder like in your picture. I’ll try to document myself more about this, thank you!
Really sorry to know there is not a simpler way to do this in klipper, somehow
Hi,
there you go! Please let me know if these are too blurry and you need more detail. As a new user I can only post a single picture so I crammed everything here, but if needed I can post multiple answers I guess
Right now I managed to avoid this issue by removing all the tmc section in the configuration and increasing the rotation_distance coefficient so that it makes up for the missed steps: it’s an ugly workaround with lots of side effects on the prints, but at least I can print again! However, it would be really great to understand what am I still doing wrong here.
Thank you so much!
You do not have a Klipper problem, but a hardware problem (Unfortunately it is not even clear, if these are really TMC drivers. Could be any other driver as well).
Background:
TMC can be operated in two modes: Standalone or UART/SPI controlled (depending on driver type)
Standalone: Current is controlled via setting VREF on the potentiometer. Firmware cannot influence this (neither Marlin, Klipper or any other firmware)
UART/SPI controlled: Current (and other driver settings like spread-cycle or stealth-chop) are controlled by the firmware
This mode needs support by the board
This mode needs properly configured / wired drivers
Setting of the potentiometer is irrelevant in this case
Your case:
The drivers and board in your case are standalone only in their current configuration. This is also the reason why you are receiving the TMC errors when trying to set it in printer.cfg. This is also the reason why the configuration you linked in your first post does not contain any TMC settings.
You can find respective guides how to change this, e.g.:
Hi Sineos,
thank you very much for your support. But how can you explain that the potentiometer stopped working after flashing klipper software? I basically did the same operations before and after flashing klipper: before, I managed to tune VREF of the extruder to 0.8V and I was happy with the compromise between heating and power. After flashing, measuring the tension to the potentiometer only gave 12V and I didn’t manage to notice any difference by moving it in either direction. How is that possible?
Thank you anyway for all the time you all dedicated to me, and I’m sorry if my questions sound super noobish but this is the first printer ever I managed to customize a bit, with basically no documentation available anywhere about its specs
You measure wrongly (make sure to touch only the metallic part of the potentiometer and a GND pin with your probes)
Something is badly damaged / fried / shorted
Klipper has no way to influence the standalone VREF.
Edit: Note that some of these potentiometers have no “endstop”. This means you can turn them by 360° degree. Such potentiometers have a “dead zone” of around 180° in which the measurement does not change.
even if just by moving a screw on the driver. Moreover, I just detached the driver and I didn’t even find the pads to solder like in your picture. I’ll try to document myself more about this, thank you!
