Help me control a stepper motor pleaaase

Hi,

I've designed a product and I need to build a prototype which includes a stepper motor that mimics the control knob/jogwheel/encoder/dial movements 1 to 1 or close to 1 to 1. So when you turn the control knob/jogwheel/encoder/dial, the motor copies in both directions. The video below demonstrates the kind of control I'm looking for and being obsessed with this, I tried contacting the person behind the video but had no reply. I even offered to buy it from him.

[www.youtube.com]

I've looking into drivers and existing circuit boards but cant find one that has kind of control. I've seen how to do it with an arduino but dont want to use it or any pc device. The closest I found is in the link below. Its perfect but is a bit jumpy and I've been trying to get my head around why that is and how stepper motors work. My limited knowledge tells me that its jumping in full steps and that other controllers can work in half steps and even less making them smoother.

Simple manual control of stepper motors without a PIC or PC

Its looking like I might have to combine the right encoder to the right controller board and thats where I hit a brick wall. I have only a small knowledge of electrics and am struggling to work out a solution.

I would really appreciate any feedback and help.

Voltage wise, it could be between 5 and 24
Stepper motor wise, what ever works really.

Thanks for your time.

Ben

I assume your second link should be [www.instructables.com]

I think it only looks more jerky because the pointer is much bigger. A typical stepper motor has 1.8 deg step, they both look about the same angle. I would suggest trying that instructable. If you want to get near 1:1, you need to find an encoder with more steps, they tend to be more expensive.

Without a microcontroller it'll be pretty tricky - is there any reason you don't want to use one? You'll need a quadrature encoder if you want it to work in both directions - a quadrature encoder has two outputs, and the order in which they trigger gives the direction of motion. If you really don't want to use a microcontroller, this is what I'd do:

Start with the quadrature encoder and a stepper motor driver that takes a direction input, and a step input (a pololu would be fine).
Connect the two quadrature encoder pins to the input of a 2-input AND gate (or NAND). Connect the output to the step pin of the driver.
Connect the two encoder pins to the S and R inputs of an SR latch. Connect the output to the direction pin of the driver.

This /should/ work, assuming I haven't made a silly mistake.

hmmm maybe, you can make a encoder knob thingy, send that pulse into a logic buffer, then drive some kinda 74xxx octet decoder? make that decoder reset at 4bits and pump that into another set of buffer logic gates that will "formulate" correct set of H bridge drive logic, that will give a some sort of manual logic to drive a H bridge? does that make sense?

Edited 1 time(s). Last edit at 03/13/2013 01:41PM by redreprap.

i just finished making the instructables and it works well. like you said the encoder hasnt got enough steps for my desired control and i now need an encoder that has more like 64 steps. i've been looking and i dont understand a lot of the information that encoder data sheets show. i know that it needs 64 ppr, 2 channels, 90 degrees square wave, but what i dont understand is the contact rating. the one i used is a 10mA 5V DC. would it matter if it is say a 1mA 10v or a 10mA 10v. i say this because i have a few encoders with different ratings they work with my circuit. will it cause damage or poor performance if the rating of the encoder is wrong?

thanks

isit because ULN drives at full step?
and i noticed the sample controller, is not logic buffered, does it affect?

benjamin.w Wrote:
-------------------------------------------------------
> i just finished making the instructables and it
> works well. like you said the encoder hasnt got
> enough steps for my desired control and i now need
> an encoder that has more like 64 steps. i've been
> looking and i dont understand a lot of the
> information that encoder data sheets show. i know
> that it needs 64 ppr, 2 channels, 90 degrees
> square wave, but what i dont understand is the
> contact rating. the one i used is a 10mA 5V DC.
> would it matter if it is say a 1mA 10v or a 10mA
> 10v. i say this because i have a few encoders with
> different ratings they work with my circuit. will
> it cause damage or poor performance if the rating
> of the encoder is wrong?
>
> thanks

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