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IndustryArena Forum > CNC Electronics > Stepper Motors / Drives > Trying to get a TMC2208 stepstick driver to work
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  1. #1
    Join Date
    Apr 2021
    Posts
    1

    Question Trying to get a TMC2208 stepstick driver to work

    Hello everyone! I have a DIY laser cutter that is currently running on some generic DM542 drivers, but I am having very strange and hard to track down issues with step-loss on those drivers when the machine makes quick and frequent direction changes. I decided I wanted to try to use some of my TMC2208 modules I have lying around, because they seem to work quite well in 3d printers which tend to use a lot of the small and quick movements as I am having trouble with. There is very, very little load on the machine as well so the relatively low current available on the TMC2208 shouldn't be a problem either.

    The issue is that I can't get the stepstick drivers to actually work in the machine. I have already confirmed that I can get a separate motor to turn properly using the drivers and an adruino to create step/dir signals, so I'm fairly certain (but not positive I guess) that my wiring and setup are correct. When I connect it to the motors in the machine though it behaves strangely. I have tried several different ways of connecting the motor to the board, and the best I could get was semi-normal movement in one direction, but just whining in the other as if the motor was stuck (but it is not). I confirmed that if I move the wires back to the DM542 it moves fine, so there shouldn't be any issue with the coils in the motors.

    Here's the "data sheet" for the modules I'm using https://github.com/bigtreetech/BIGTR...0%20manual.pdf

    My controller is a Ruida rdc6445g.

    Things I've tried, many of which are just out of desperation without knowing if they are required/helpful:

    - Increasing current setting on the tmc2208. This did resolve another issue I had, but not the one listed above
    - Putting a 100μF filter capacitor across the motor voltage input rails (no idea if it's actually required)
    - Putting a 10k pulldown resistor on the step pin (no idea if it's actually required)
    - Changing which coil is connected to the A and B outputs on the board

    Things I have a hunch about, but don't know and/or can't find information about:
    - the DM542 drivers have pul+/- and dir+/-, while the tmc2208 modules have just stp and dir. I believe this means that the DM542 uses differential inputs and the TMC just uses direct? Could this be contributing to my issues?
    - The output from the rdc6445g for each axis has pul, dir, and +5v. On the DM542 I have +5v going to both pul+ and dir+, and the other two pins going to pul- and dir-. On the TMC2208 module I am using the +5v pin as the logic Vin for the whole board, and the pul/dir pins as the stp/dir inputs. My assumption is that the +5v is used as the reference high and the pul/dir outputs from the controller pull that low.

    Sorry for the very long post, I tried to include all the information I have. Please let me know if there is anything I have left out! Very much appreciate any help that anyone can give!

  2. #2
    Join Date
    Dec 2012
    Posts
    199

    Re: Trying to get a TMC2208 stepstick driver to work

    DM542 uses a opto coupler for the inputs. The motor currents are completely separated from the logical inputs by this.
    To my opinion, the DM542 is far superior to the TMC2208. It has a good protection for your controller by using these opto couplers
    TMC2208 has one ground. Your controller should be connected to that and supply good +5v pulses for the step and dir signal and it needs the filter capacitor
    The TMC2208 has internal pull down resistors, so external they are not needed

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