6wire 2phase 5Volt Steppers With Tiny G

Home › Forums › TinyG › TinyG Support › 6wire 2phase 5Volt Steppers With Tiny G

Viewing 6 posts - 61 through 66 (of 66 total)
1 2 3 4 5
  • Author
    Posts
  • September 5, 2021 at 3:52 pm #12077
    akfreak
    Member

    I think I may of found a problem. I measured the pins (I dont know what you call these pins, the holes above Motor 1 2 3 & 4., but the holes on my board have now pin headers installed, and I measured these pins with a voltmeter. The 3.3V measured 3.4v dc so we are good. the Enable pin also rests at 3.4V so this could be my problem.

    “Connect Enable[bar] to ENA – on the DM556
    Connect Step- and Dir- on the DM556 to tinyG Gnd (not DM556 GND)
    Connect ENA+ on the DM556 to the 3.3V lead on J17”

    Not Sure what “[bar] is, is it typo? Or, there is a little Bar line above Enable on the PCB. Anyways if the Enable pin on the DM556 is Active Low and we are sending 3.3V to ENA+ because its hooked to 3.3v on the tinyG and DM556 ENA- is hooked to the Enable of the tinyG resting at 3.3v this is an issue, no? Our enable circuit on the DM556 is 3.3V on both the negative and positive.

    I am not sure how the controller works, if in fact it rests as a closed circuit and needs a signal to open the connection between the stepper coils to unlock it, this may very well be the problem. What do you think?

    I am not going to mess with this until I hear from you.

    September 7, 2021 at 7:49 pm #12078
    cmcgrath5035
    Moderator

    I am not sure how the controller works, if in fact it rests as a closed circuit and needs a signal to open the connection between the stepper coils to unlock it, this may very well be the problem. What do you think?

    I am not 100% sure what you are asking here, but I can guarantee you the detailed answer is well beyond the scope of what we can do here. Keep in mind that most all logic leads and the actual connection to the stepper windings are pulses, not DC levels that you can read usefully with a voltmeter. Perhaps what follows will help.

    The Term “enable – bar”, silkscreened on my tinyG as enable with a bar across the top, is standard speak in logic circuits that when I say “Enable is active”, the enable -bar lead will be a logic low, approx 0 to 0.1V.
    That is the way tinyG firmware signals Enable is active or inactive. The enable lead is programmed to be ‘active-low’ because that is what the onboard 8825 stepper driver chips expect.

    Upon reset, tinyG will turn on the driver device for $mt seconds. During that interval, the step lead and dir lead will be off, and measure 0 volts.
    When the stepper driver device sees enable on and pulse and dir off, the stepper device is signaled to hold position with pulsed voltage applied to all 4 winding leads at appropriate phases. After $mt seconds, the enable lead turns off, which is 3.3V.

    Go back and see if you observe that behavior, voltmeter measuring the enable-bar pin before and after you hit the reset button.
    Power up tinyG, wait 5 seconds. now probe the enable bar pin, it should be high(3.3v). keep the prob on the enable bar pin and hit reset, you should
    see the pin drop low for $mt seconds, then return high.
    Wiring 3.3vdc to enable+ on the DM556 and the enable bar to enable- on the DM556 inverts the enable bar logic.

    All this assumes that the DM556 inputs are all positive logic. You need to get me the spec sheet URL. Just copy it from browser and paste it her(the URL, not a screenshot of the image.

    September 7, 2021 at 7:52 pm #12079
    cmcgrath5035
    Moderator

    You should read this link(from the yellow area at top of this thread), it may help you better understand how stepper motors work,
    https://synthetos.com?post_type=topic&p=6214

    Also, Please start a new thread, this one is getting way too long and getting hard to navigate

    September 7, 2021 at 7:59 pm #12080
    cmcgrath5035
    Moderator

    If you want to dig even deeper, you can pull up this datasheet for the TI 8825 driver, the one that is on tinyG(four times).

    https://www.ti.com/lit/ds/symlink/drv8825.pdf?ts=1631030020835&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDRV8825

    September 7, 2021 at 8:02 pm #12081
    akfreak
    Member

    in summary what I asked is are you sure the way you told me to hook the Tinyg to the Driver is correct? its neither active low or high, its a combination of both. also How is it possible to post a photo in this forum? I can post Youtube videos but nt a photo or a link. if I try to add any link the post never posts it returns a black screen.

    September 7, 2021 at 8:57 pm #12082
    cmcgrath5035
    Moderator

    No, I am not sure because I don’t have any specific information about the DM556 you purchased, I am using some reasonable assumptions about it, specifically that the pulse, dir and enable inputs are positive logic.

    Do you have access to a cloud drive service, such as Gdrive or Onedrive or DropBox (or…)
    This is a rather un-modern forum tool and does not have great support for attachments.
    Best way to make a picture available is to copy it to the cloud drive, copy the url to your clipboard then paste that text URL into your forum post

    That is how all the URLS I have provided you are inserted. I am assuming they are working for you, is that accurate?

  • Author
    Posts
Viewing 6 posts - 61 through 66 (of 66 total)
1 2 3 4 5
  • You must be logged in to reply to this topic.