Stepper Pepper…

November 3, 2012 at 3:10 pm Leave a comment

So as mentioned in an earlier post, I’m interested in making my Raspberry Pi control a stepper motor as a first step into the world of physical computing. Not content to simply buy a board (like the StepRocker) that takes care of the grit in this process, I went boldly forth and bought a Pololu carrier board for the A4988 stepper driver (a few of them actually, under the assumption I’ll blow at least one of them up).

Well, it’s not as easy as all that. Without boring into all the minute details, I can say that my early trials have not been encouraging through no fault of the Pi. My latest test last night took the Pi out of the equation and simply used a couple of push-buttons to replace the inputs from the Pi. This has the virtue of being run from the same power supply for both the +5V and +12V lines, and has the fewest variables which are well controlled. Still no success in making *controlled* steps with the motor. The driver will occasionally get into this weird state where it steps the motor 10’s to 100’s of times on it’s own, in a seemingly random direction (though always in the same direction once it gets going). So it very much resembles some sort of demonic possession of circuit… I’m sure of it. 

I’ll continue to mess with it and see if I can figure out what is going on. I suspect that noise or a floating line somewhere is responsible for the random bursts of motion, so tracking that first may help solve the other problem.

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