About External Stepper Drivers.

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  • May 3, 2014 at 6:08 pm #5873
    Uchiha Lawliet
    Member

    Hello everyone !

    I have some questions about stepper drivers (external).

    What kind of requirements must complain an external driver to be used on TinyG board (v8) ?

    Do you know (or suggest) which external drivers could be used on TinyG ?

    Are there external drivers that don’t work with TinyG ?

    I want to use stepper motors like Nema 34 (or even higher), but, I don’t know which external stepper drivers could be used.

    I have a Gecko Driver (http://www.geckodrive.com/geckodrive-step-motor-drives/g210x.html).

    This driver has Direction (7), Step (8) and Common (9) entries. These entries were used to be connected on TinyG (Z Axis) at Direction, Step And Ground pins.

    I did some tests, but at the moment, I could not have communication between TinyG and the Gecko Driver. This driver works fine using another board (similar to TinyG).

    I have observed some points about TinyG (Voltage):

    STEP PIN is between 0.8 – 29 mV.
    DIRECTION PIN is between 0.8 mV – 3.4 V.
    ENABLE PIN is between 0.8mV – 3.4 V

    Please, any information that you could give will be great !

    Thanks for your time !!!

    May 4, 2014 at 2:15 am #5874
    alden
    Member

    The step pin should also outputting 3.0v to 3.4v. 29mv is very low. What axis are you trying and does the low voltage occur on all axes?

    May 4, 2014 at 2:45 am #5875
    Uchiha Lawliet
    Member

    Using and testing only Z Axis, I have detected that STEP Pin is not major than 29mV (forward motion and backward motion). Without motion is up to 0.9mV

    Other two pins (DIRECTION, ENABLE) are up to 3.4V.
    For the moment, I don’t have measurements for the other axes.

    TinyG is powered with 12V @5A.

    May 4, 2014 at 2:50 am #5876
    alden
    Member

    If you are measuring with a volt-ohm meter what you might be seeing is the step line acting as a pulse-width modulated line. You would not measure 3.4v in that case, as the steps are very narrow (a few microseconds). Have you tried measuring the voltage on an oscilloscope? You should see a low base of well under one volt with narrow pulses at 3.0 to 3.4 volts.

    May 4, 2014 at 3:05 am #5877
    Uchiha Lawliet
    Member

    Ok, I see.

    In that case, I saw here cases where users had to use “level shifters” or “octal bus transceiver” to connect their external drivers to TinyG.

    I suspect that their external drivers only accept 5V signals, and in my case the driver accepts 3v-5v signals. I’m a beginner on this and I’m trying to set up my TinyG board with external drivers. I have some nema 23 and nema 34 motors.

    I’m very sorry if my questions are too elementary. Any help would be appreciated.

    Thank you again !

    May 4, 2014 at 3:12 am #5878
    alden
    Member

    No problem with the questions. There are a few things that need to be satisfied for an external driver to work

    – Voltage. The external driver must accept 3v pulse signals or you will need a level shifter of some sort. I like the 74HC125 or 74HC126 (OnSemi is a good manufacturer). Power the chip with 5v and a 3.3v logic input will output 5v.

    – Pulse timing. The external drive must be satisfied with step pulse widths down to about 2 microseconds. Use the edge branch (412.01 or higher) if you need these widths. THe code in the current master branch (380.xx) outputs pulses about 1 microsecond width. We added some pulse stretching later which is currently not in the master branch.

    – Enable. THe enable signal from the TinyG is active low.

    May 4, 2014 at 1:58 pm #5879
    Uchiha Lawliet
    Member

    Ok, I’ll check these settings.

    Thanks !

    May 5, 2014 at 12:29 am #5880
    Uchiha Lawliet
    Member

    Hello Alden

    I have used the edge branch with current version 412.01
    It appears that step pulse width on master branch is not enough for my external stepper driver (Gecko G210X, 1uS – 4.5 uS).

    For anybody that may have this problem (like me), just, try to use the edge branch, that branch solved my problem. Using that version I could move a stepper motor nema 34 @5A using gecko driver g210x.

    It could be better if these new features (edge branch) were available on master branch.

    Also, I found that user named “scottcarlson” had the same problem using Gecko Drive 201x and solved it on the same way (https://github.com/synthetos/TinyG/issues/61).

    Finally, thanks again Alden, thank you very much for your help !

    I believe I will be here very soon with more questions !

    Thanks !

    June 14, 2014 at 6:49 pm #6148
    SRC
    Member

    Uchiha,

    I’m just getting started on a CNC project…ground up.

    I need to power NEMA 34 motors (yet to be spec’d) and I really want to use the Tinyg board.

    I have no background in electronics and I’m reading everything I can about this.

    You’ve been successful running motors that require external stepper drivers.

    If you were starting from scratch, would you use the Gecko G320x drivers or is there another option?

    Basically, using the Tinyg and G320x drivers “should” I be able to make that configuration work?

    Really appreciate any guidance you can provide (not sure if I should reply to your post or start another one).

    Thanks!

    June 26, 2014 at 3:02 am #6246
    Uchiha Lawliet
    Member

    Hello SRC !

    Uhm…., let me see…, In fact, I’m in the same condition as you. I’m a beginner on these topics… Just take my comments only as reference, because I’m not an expert.

    I saw the Gecko G320X spec, and there are some differences between 210x gecko drive and g320x gecko drive. (For example motor current, power dissipation, input frequency and step pulse “0” time, and…., the motor target).

    To be honest, I don’t know the real differences between stepper motor and servo motor, because g210x is based for stepper motors, and g320x is based for servo motors. I don’t want to lie on this topic, but, I think you should do a deep research on this and what kind of motor you must use for your machine. In my case I have used stepper motors connected to external stepper drivers.

    For the other side, nowadays I was using tinyg and another board with similar conditions. I have tested stepper drivers like Gecko G210X and CW-5045 on tinyg board, and both of them are working. Serious tests are not yet ready (with built machine, I’m working on that…), but, my tests were only using these stepper drivers with nema 23 or nema 34 motors. (In the case of G210X stepper driver, I have tested nema 23 and nema 34, and, in the case of CW-5045 stepper driver I was using only nema 23 motors, because for this driver the amperage limit is 4.5A and my nema 23 motor is up to 4.2A…my nema 34 motor is up to 5.0 A. As you can see, this last motor is not the right choice for CW-5045 stepper driver).

    I hope this information was useful. If you have more questions, I will try to answer them with the most useful data….

    July 4, 2014 at 1:27 pm #6326
    SRC
    Member

    Uchiha,

    Thanks for your reply…was off sailing for 2 weeks and didn’t get a chance to thank you and ask some additional questions.

    I’m pretty sure I’m going to go with the TinyG board, and Gecko G320X drivers with NEMA 34 stepper motors (drawing < 6 amps).

    I’d appreciate any information on how you wired those, if you could provide a picture that would be very helpful.

    The main thing is that you have succeeded in hooking up the Gecko G320X drivers, so I know it can be done (perhaps even by me!) if I have some guidance.

    I’m close to ordering the board/drivers/stepper motors but I won’t have the gantry for another month or so.

    Anyway, just wanted to reach out to you and learn from your experience and I’m very happy you’ve been able to get that configuration working.

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