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    Building a DIY public domain low cost stepper motor analyzer

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    • kraegarundefined
      kraegar
      last edited by

      Awesome project! Thanks for sharing!

      Co-Creator of the RailcoreII CoreXY printer
      https://www.thingiverse.com/thing:2407174

      1 Reply Last reply Reply Quote 0
      • JRDMundefined
        JRDM
        last edited by

        This is neat. One time I thought of building a step motor dynamometer to compare motors by looking at their torque curves. I wish I followed through. Maybe that can be another module for this device?

        1 Reply Last reply Reply Quote 0
        • JoergS5undefined
          JoergS5
          last edited by JoergS5

          This could be a good project for a electronic magazine (I mean as an article in the magazine with explanation): a useful topic for many users, nice images and a PCB project. Something like Elektor in germany.

          1 Reply Last reply Reply Quote 1
          • zaptaundefined
            zapta @DocTrucker
            last edited by

            @DocTrucker said in Building a DIY public domain low cost stepper motor analyzer:

            Does the detail of the plots change under acceleration vs deceleration? Any indication that lag or advance of the rotor may be delectable?

            Good question. I don't know. I clearly observed that the current does not reach full amplitude when the speed was too fast that voltage and stepper combination but I don't know if the current signals are sufficient to detect missing steps.

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            • zaptaundefined
              zapta @T3P3Tony
              last edited by

              @T3P3Tony said in Building a DIY public domain low cost stepper motor analyzer:

              @zapta this is a great project! thanks for documenting it as you go through. Worth a submission to hackaday once complete I think!

              Hi Tony, yes I plan to do that, to get more awareness. My goal is to provide a baseline hardware and firmware such that more knowledgable and creative people can use to provide useful tools for the community.

              1 Reply Last reply Reply Quote 2
              • zaptaundefined
                zapta
                last edited by

                After procrastinating on this project for some time I realized that having to implement the UI with a low level screen API was distracting so I decided to switch to a smart touch display (Nextion 4.5") and things started to move fast. Here are a few pictures with the current state. Next I plan to redesign the PCB for the new LCD and clean up the UI.

                The old PCB with connected to the new display:
                f1eba650-5594-4108-9360-c8693898c6ca-image.png

                The home screen with summary data:
                f8589f7f-505b-43cb-aff8-5bb9543280c1-image.png

                The setup screen. It allows to set the zero current and to reverse the steps direction.
                3efd6fc5-1bbe-47df-921f-c62e53f94838-image.png

                The distance graph. Graphs moves up/down in real time with the steps counter:
                5afe5ebf-70c8-499d-8a37-c2d25e6a6f3a-image.png

                Histogram of time by speed. I am thinking adding a similar screen with histogram of distance by speed.
                014b6ada-9932-4f5a-9509-d35af6385854-image.png

                Histogram of peak current vs speed. In this example, a 12V 1.2A stepper, the max current starts to drop at ~7000 steps per sec.
                c6bf7903-760b-473f-8beb-529981f81762-image.png

                A tachometer that shows speed in real time.
                88a789db-11fc-46ed-8c83-a2b4b17d3508-image.png

                A capture of the current signals in the two stepper coils. This one is at high speed with only 12V supply which resulted in poor current pattern, close to the speed limit of the system. (ideally the two signals should look like sine/cosine).
                c98ab65d-745b-44fc-84fe-b137e89bc98a-image.png

                JoergS5undefined 1 Reply Last reply Reply Quote 3
                • JoergS5undefined
                  JoergS5 @zapta
                  last edited by

                  @zapta your project is very interesting. Can you tell me please whether you were able to analyse currents with microstepping and to which detail?

                  Thank you for pointing me to the ACS70331. I have a couple of ACS712, but they are much too slow.

                  I would like to analyze the correlation between step commands to the TMC, the created currents from TCM to stepper and the resulting movement of the stepper.

                  zaptaundefined 1 Reply Last reply Reply Quote 0
                  • zaptaundefined
                    zapta @JoergS5
                    last edited by zapta

                    Hi @JoergS5, think it shouldn't be too difficult to decode x16 microsteping. When going through a full step, the current in the two coils behave like the graph below. X16 can be achieved by breaking the cycle to x4, x2 and x2:

                    x4 - detection of a quadrant (90deg) is already already done and needed to determine the direction.

                    X2 - each quadrant can be divided int two (45deg each) by comparing the absolute value of the two channels.

                    X2 - each sub quadrant can be divided by 2 using the ratio of the high coil current to the low coil current.

                    I think this is straight forward and doable, given the two currents, and can also be come manually using the two current readings.

                    d008d56a-dc4f-4bec-857a-3b172052355a-image.png

                    BTW, I send the new PCB layout to manufacturing. Should arrive in a few weeks. It's a small 40x50mm board.

                    1344139d-7746-45bb-9d35-14aeda11a72c-image.png

                    All the source files are on github and should work though I plan to do some cleanup.

                    https://github.com/zapta/misc/tree/master/stepper_analyzer

                    Schema is in the link below. As you can see there is no much there:
                    https://github.com/zapta/misc/blob/master/stepper_analyzer/kicad/main/stepper_analyzer.pdf

                    JoergS5undefined fcwiltundefined 2 Replies Last reply Reply Quote 1
                    • JoergS5undefined
                      JoergS5 @zapta
                      last edited by JoergS5

                      @zapta Thanks for your information and the source location. Lucky me I bought a Nextion 3.5 last year, because I liked the idea that the display offers GUI logic, so I can start with your source.
                      It will take some time until I can start with the project, but I can keep you informed what I develop.

                      1 Reply Last reply Reply Quote 0
                      • fcwiltundefined
                        fcwilt @zapta
                        last edited by

                        @zapta said in Building a DIY public domain low cost stepper motor analyzer:

                        All the source files are on github and should work though I plan to do some cleanup.

                        https://github.com/zapta/misc/tree/master/stepper_analyzer

                        I don't see how to download all of the files related to this project.

                        Does each file have to be downloaded separately?

                        Frederick

                        Printers: a small Utilmaker style, a small CoreXY and a E3D MS/TC setup. Various hotends. Using Duet 3 hardware running 3.4.6

                        A Former User? 1 Reply Last reply Reply Quote 0
                        • A Former User?
                          A Former User @fcwilt
                          last edited by

                          @fcwilt easy way is to clone or download the whole https://github.com/zapta/misc repository.

                          Alternatively you can turn to google to try and download just a sub directory from github

                          fcwiltundefined 1 Reply Last reply Reply Quote 0
                          • fcwiltundefined
                            fcwilt @A Former User
                            last edited by

                            @bearer said in Building a DIY public domain low cost stepper motor analyzer:

                            @fcwilt easy way is to clone or download the whole https://github.com/zapta/misc repository.

                            Well that is certainly not the way I thought it would be done but if it works...

                            Thanks.

                            Frederick

                            Printers: a small Utilmaker style, a small CoreXY and a E3D MS/TC setup. Various hotends. Using Duet 3 hardware running 3.4.6

                            A Former User? 1 Reply Last reply Reply Quote 1
                            • A Former User?
                              A Former User @fcwilt
                              last edited by

                              @fcwilt said in Building a DIY public domain low cost stepper motor analyzer:

                              if it works...

                              it does. but packing several projects into a single repo doesn't lend itself well to sharing or collaboration - but it is easy for a single user.

                              anyways https://stackoverflow.com/questions/7106012/download-a-single-folder-or-directory-from-a-github-repo and other search results does provide options but to me its always seemed like more hassle than just getting the whole thing and discarding what I don't need/want.

                              zaptaundefined 1 Reply Last reply Reply Quote 2
                              • zaptaundefined
                                zapta @A Former User
                                last edited by

                                @bearer said in Building a DIY public domain low cost stepper motor analyzer:

                                it does. but packing several projects into a single repo doesn't lend itself well to sharing or collaboration

                                Sorry about that. This is my catch all 'misc' repository. I plan to clean up the stepper analyzer in the next week or two so will also move to an independent repository.

                                Meanwhile, if you encounter any problem, let me know here. I will monitor this thread more closely.

                                Flushing the firmware has two parts, flashing the Nextion 3.5" using a micro SD card or the nextion designer with a serial port, and flashing the Teensy 4 which I currently do with the Arduino IDE (need to install the Teensy 4 extensions) but am looking for a simpler way (any suggestions?)

                                A Former User? 1 Reply Last reply Reply Quote 1
                                • A Former User?
                                  A Former User @zapta
                                  last edited by A Former User

                                  @zapta said in Building a DIY public domain low cost stepper motor analyzer:

                                  but am looking for a simpler way

                                  platformio? (for the teensy at least)

                                  zaptaundefined 1 Reply Last reply Reply Quote 0
                                  • zaptaundefined
                                    zapta @A Former User
                                    last edited by

                                    I copied the stepper analyzer files to a dedicated repository https://github.com/zapta/stepper_analyzer (will delete files from the old repository later).

                                    It also includes a release directory with binaries for the teensy and the nextion 3.5". The teensy firmware can be flashed with a teensy loader (https://www.pjrc.com/teensy/loader.html) and the nextion using its sd card.

                                    It's still rough and I plan to clean it up in the next week or two. Please let me know how it works for you.

                                    1 Reply Last reply Reply Quote 2
                                    • A Former User?
                                      A Former User
                                      last edited by

                                      Thats awesome, its on my list to try and build one! Thanks for putting this out there man!

                                      zaptaundefined 1 Reply Last reply Reply Quote 0
                                      • zaptaundefined
                                        zapta @A Former User
                                        last edited by

                                        The new PCBs arrive and I like how small and simple they are:

                                        597e97f4-1f2b-4126-9563-fd2f2cd58363-image.png

                                        I also added a retraction analysis screen. It is cumulative such that retract 10 steps extruder 3 steps, retract 5 steps will show retraction of 12 steps.

                                        The graph moves in real time so the camera didn't capture it well. The little noise at the bottom of the graph are tiny retractions due to pressure advance (0.08).

                                        667e56f2-cc09-4573-91c1-347186ffae94-image.png

                                        I plan to commit the changes to github later today.

                                        1 Reply Last reply Reply Quote 3
                                        • fcwiltundefined
                                          fcwilt
                                          last edited by

                                          Hi,

                                          Have you considered building a small batch of complete units and selling them to us poor souls who would love to get our hands on one?

                                          Frederick

                                          Printers: a small Utilmaker style, a small CoreXY and a E3D MS/TC setup. Various hotends. Using Duet 3 hardware running 3.4.6

                                          zaptaundefined 1 Reply Last reply Reply Quote 1
                                          • A Former User?
                                            A Former User
                                            last edited by

                                            I'd could be down for crowd sourcing myself one if such a thing were to be a thing.

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