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Problems with stepper motors

Discussion in 'Sensors and Actuators' started by marco3189, Jun 16, 2013.

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  1. marco3189


    Jun 16, 2013

    I'm building a goto system for my telescope using an Atmega162 as cpu, two Pololu A4988 stepper drivers and two NEMA-17 motors rated 2,4 V and with 1 ohm resistance per coil.

    At the beginning I was able to move them at 300X the sideral rate with acceleration, now I'm able to reach only about 150X the sideral rate. Motors are very instable and if I simply touch with my finger the rotating part it freezes and I need to give it manually a small acceleration. I ear also a strange periodic sound.

    At 300X the acceleration doesn't work anymore and if I try to unlock it with my fingers it seems to to a small fraction of rotation and the with strange rumors it blocks again.

    Sometimes I forced it to move, maybe I've broken something?

    The A4988 has a current regulator that can be tuned with a potentiometer. Before, at 1/4 of turn the A4988 was a little warm and if I increased over the current it was very hot (I've already burned two of them in this way...) , now even at full position the A4988 isn't warm.

    For testing the stepper driver I've connected MS1, MS2, MS3 to vcc (16 microstepping), enable to ground and reset to vcc.

    Can you help me?

    Thank you

  2. wannabegeek


    Aug 17, 2011
    I've recently been writing control program for some steppers and found a forum
    dedicated to steppers.

    Sounds like a cool project. The motors I'm programming come with a complete terminal interface, but I've always wanted to try to build my own.

    Good luck.

    CDRIVE Hauling 10' pipe on a Trek Shift3

    May 8, 2012
    Hi Marco and welcome to EP. Schematics are always helpful if not essential. They're easy to post by clicking the paper clip. ;)

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