smooth microstepping which logic chip which steppermotor?

StefanL38

Hi I have build an EggBot http://www.egg-bot.com/

The controllerboard called EiBotBoard uses an Allegro 4983 -Chip
http://www.allegromicro.com/en/Products/Part_Numbers/4983/

This chip can do 1/16th step.
I use two unipolar steppermotors that are wired for bipolar use with the EiBotBoard

The lines look a little edgy like tiny stairs

My question is If I use bipolar steppermotors that are optimised for microstepping
will they act smoother?

Which other kind of chip can do even higher resolution microsteps? (1/64th 1/256th)

Could a microcontroller (propeller-chip) do all the details of creating microsteps
when using two fast H-bridges?

any kind of hints and tips are much appreciated

best regards

Stefan

ElectricAye

StefanL38 wrote: »

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Which other kind of chip can do even higher resolution microsteps? (1/64th 1/256th)

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Stefan,

I think the L6208 chip is capable of doing whatever number of microsteps you might desire. If I remember correctly, you can set how much each microstep "jumps" by adjusting its Vref signal via PWM inputs controlled by the Propeller. I made one of these that did 10 microsteps per step and it seemed to work okay, but by adjusting the PWM to finer detail via software, I suppose it would provide finer mechanical motions. I think if you switched to using bipolar steppers with your present system, you would probably get the same edginess simply because that's what microsteps are - they are just smaller stair steps than what is normally used. But the L6208, or any chips that utilize a similar PWM-controlled Vref, should do the trick for you. I can't say I'm very experienced with such things, but that's my 2 cents worth. I hope it helps.

http://www.st.com/stonline/books/pdf/docs/8607.pdf

good luck,
Mark

http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=2556626&k=l6208