Need Help!- microstepping board

[logix]

hi all,

It's my first project. I want to build low cost microstepping controller board with PIC 16F628A.
I searched in this forum before. I found some linistep schematics and firmwares,make me confuse.
Could you help me which boards and firmwares are working fine for 16F628A?
I use unipolar stepper motor less than 1A. I will connect the board to PIC microcontroller directly.

Thank's in advance.

[defector]

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I am rarely on forums but very interested in stepper topics. Please see the folloving docu for a code snippet at the end of same. This might help You a bit.

[PDF] MICROSTEPPING STEPPER MOTOR DRIVE USING PEAK DETECTING CURRENT ... ... http://www.st.com/stonline/products/...re/an/8700.pdf

Best Regards, Goran

[defector]

Sorry for the bad cut & paste, did't see it in quick reply.

[logix]

hi Goran,

Thanks for your information, but what I mean is linistepper board and firmware.

[defector]

This reference was only for the control loop given in code at the end of document. The code is not for PIC anyway, but can give some ideas what should be done. This is a good reading, sory it didn't help.

Best regards,
Goran

[defector]

Hello again,
Check this page, this is a project with PIC16F627.
http://www.embeddedtronics.com/microstep.html

If You want to use linistep board or similar, You will need current feedback of
some kind. For microstepping it is important to have a current control - current equals flux - equals torque.
Total flux must remain the same, you are only distributing it by sine, cosine on poles to get smooth microstepping with as constant torque as possible. (Other issues start here).
Current control is a must for microstepping.

Best regards,
Goran

[Coco Sapone]

In order to drive in microstepping mode a stepper motor using PIC micrrocontrollers I recomend to use the idea from the page telepicdata

[James Newton]

I don't see anything at telepicdata about controlling a stepper motor with a PIC... he uses a L6208N... I guess the PIC generates the step and direction pulses for that, but that doesn't have anything to do with microstepping..

The embeddedtronics project, again, is not using the PIC to microstep. It uses a LMD18245 and the PIC just sends step and direction.

Same again with the ST app note...

The Linistepper DOES use a PIC to generate the microstepping levels, and the current feedback is an important part of good high speed operation, but it is NOT required for the generation of microsteps.

Getting back to the original posters question: What is it about the Linstepper that is confusing? Can I help to explain something?

[Coco Sapone]

Originally Posted by James Newton I don't see anything at telepicdata about controlling a stepper motor with a PIC... he uses a L6208N... I guess the PIC generates the step and direction pulses for that, but that doesn't have anything to do with microstepping.. The embeddedtronics project, again, is not using the PIC to microstep. It uses a LMD18245 and the PIC just sends step and direction. Same again with the ST app note... The Linistepper DOES use a PIC to generate the microstepping levels, and the current feedback is an important part of good high speed operation, but it is NOT required for the generation of microsteps. Getting back to the original posters question: What is it about the Linstepper that is confusing? Can I help to explain something?

Hello James,

The PIC16F877A generates the clock pulses and direction, but it also generates 2 PWM that change the voltaje at VREF of the chip L6208. You must generate two senoidal waves using this two PWM otputs in order to give one sin signal and other cosine signal. Tell if that helps.

























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[James Newton]

That is confusing to me... if the PIC generates the waveforms, why does it also need to generate step and direction? Sorry, I don't know anything about the L6208.

[Coco Sapone]

Originally Posted by James Newton That is confusing to me... if the PIC generates the waveforms, why does it also need to generate step and direction? Sorry, I don't know anything about the L6208.

Hello James,

There's a lot of web pages with microstepping and L6208 application notes, here I give you a good material to read:
http://www.otocoup.com/DocTech/Stepp..._microstep.pdf

It is very well expalined.[/B]