Help with my Tiny G

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  • June 30, 2017 at 4:56 pm #10428
    nimu7418
    Member

    I have a V8 that I am putting together a CNC machine with. I am using 4 servo motors rather than stepper motors. Can this application work for servo/encoders and the tiny G?
    I only have seen mentions of stepper motors working with this system. I see 4 sets of pinouts above the motor number and those were the ones I was hoping to use. the common, enable, step, direction, and ground.

    each motors common has 5V coming out of it and I was hoping to just connect that to the controller but the controller only has a pinout above the first motor, can I hook them all up on a common connection to that 3.3v port?

    July 1, 2017 at 9:06 am #10429
    cmcgrath5035
    Moderator

    tinyG does not support servo motors.
    The signal interface to steppers, one per motor interface(tot 4) is step,dir,enable and gnd; all are outputs.
    They can drive external stepper drivers if 3.3v logic works for the ext driver, otherwise a logic level translator is required (eg 3.3v to 5v).

    I have seen discussion of external servos that will work with this interface, unconfirmed and no experience here.

    I would not recommend drawing extensive power from the tinyG to power external circuits; thermal dissipation issue with the on-board regulator.

    July 1, 2017 at 1:49 pm #10430
    nimu7418
    Member

    Hmm, ok so I can’t use the tiny G with servo motors? I know the four cables out of the stepper are the a a- b b-, which would go directly into the those green ports. Wouldn’t the other holes(ports) in the board be used from a motor driver? But above those ports j17, j18 etc, can those not be used for a servo motor’s encoder directly?

    July 2, 2017 at 10:44 am #10431
    cmcgrath5035
    Moderator

    Hmm, ok so I can’t use the tiny G with servo motors?

    Correct, alt least for a ‘classic’ servo that feeds position back to the driver device, expecting the driver device to keep trying until a commanded move is actually made.
    tinyG does not have hardware ports to read the feedback from the servo nor does it have FW to “keep trying”.

    July 2, 2017 at 11:08 am #10432
    nimu7418
    Member

    I appreciate all the help, I will look into this stuff a bit more and get back to you. Just a clarifqction you are saying this board does not do any sort of feedback loop. Do you know exactly what those porta j17, j18 etc are for?

    July 3, 2017 at 8:50 am #10433
    cmcgrath5035
    Moderator

    J17,J18, etc are the step, dir, enable signals from the micro controller to the onboard driver devices. They are controller outputs, 3V logic.
    They are provided to interface with external Stepper drivers for those needed higher power drive to steppers.
    More info here:

    And, correct, no position feedback loop.
    TinyG keeps track of position based on the number of step pulses sent since the ‘current position’ was sent.

    July 3, 2017 at 11:54 am #10434
    nimu7418
    Member

    Thank you again.

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