View Full Version : Bipolar Stepper Drive
11-05-2006, 05:47 PM
Hi I was just wondering if anybody had plans to make or has made a bipolar stepper driver using a prop chip.
Would like to have a crack at it myself, but have a long way to go.
I tried using AVR's in the past, but found the help for begginners a little lacking.
I have found the documentation and support for the prop pretty sweet, and haven't had the feeling of banging my head against a brick wall at all.
Any help would be appreciated.
11-05-2006, 06:18 PM
There has been some talk about it in this recent thread: http://forums.parallax.com/showthread.php?p=613886
Paul Baker (mailto:firstname.lastname@example.org)
Propeller Applications Engineer
Parallax, Inc. (http://www.parallax.com)
11-05-2006, 07:07 PM
Take a look at this article, might get you going:
SPIN code is here:
This is also some good info when working with steppers, page 99 of the following document:
Attached is my modified version on the Aug 2006 N&V article, added TV_TEXT output. Used a NEMA 17, 200 step per revolution, stepper motor (17PM-K223) (http://www.allsurplus.net/HybridSeriesStepMotors.pdf)·powered with a +24 VDC 3 Amp power supply.
Driver Chip: L293D - QUADRUPLE HALF-H DRIVER
Post Edited (Mike Cook) : 11/5/2006 2:42:52 PM GMT
11-05-2006, 07:54 PM
I am using Propeller to run my SuperMill.· Propeller controls three stepper controllers - two IB463s and one Gecko.· Performance of the mill is superb.
I would be happy to share the code with you if it would be of value.· Remember that my mill is an MF70 running on 3 axes.
Don't have VGA?
11-06-2006, 04:14 PM
Thanks guys, Mike that stuff is just what I need, just gotta read up, cheers.
Sid, I would love to see some pics of your setup, and yes the code would be awesome, I am not much of a programmer (yet) but plan to get into that side of things just as soon as I can clear out those damm cobwebs from the old grey matter...
I need to upgrade the motor drivers on my cnc router and thought the prop would be a more elegant way to do this rather than building another generic driver, also including closed loop feedback via quadrature encoders is high on the "to do" list.
11-06-2006, 08:23 PM
Russell, here is a copy of the program that runs my mill.· A few comments - it is not a CNC machine.· When I want to make a new board, I draw the etch paths in Expresspcb.· Each move is written down with direction· - X or Y - and the ending coordinate.· Not the distance travelled, but the ending coordinate.· Example:
These figures are copied into an Excel program which converts the data to a format a Stamp can read.
This data is then processed by a Stamp program I wrote which converts the patterns to L(eft), R(ight), I(n) or O(ut).· The resultant list is copied from the debug screen and pasted into my Propeller program as a DAT list.· The DAT list is read by the Propeller and generates the instructions for the steppers.· When the Propeller reads an instruction to go L(eft) it looks at the last L(eft) position - xpos - and calculates the distance to travel to get to the new coordinate.
You will note that in the reset method the values of Xppm and Yppm are defined.· These are the number of pulses it takes for the mill to travel 100mils.· I can adjust these value by as little as one pulse, which provides incredible accuracy.· As near as I can tell, the travel error is about .0005 mils.
The program uses Mike Green's OS.· I did not include any of the objects used by the program.· If you would like these please let me know.· Also, if you have any questions about why I did what, I will be happy to answer them.· Please study the program carefully - it was written over a long period of time and is probably not arranged in the most logical manner, but it works beautifully.
Don't have VGA?
11-07-2006, 05:48 PM
Sid, that is pretty impressive stuff, I didn't realize that you were using the prop to take care of the actual step generation. Are you a member of CNC Zone ? I bet there would be a few people there interested in what you have done.
All I was going to do for my setup was to use the prop to get the step and direction pulses from the computer running the G-code and drive via a bridge the steppers, but have to ability to use microstepping, as this makes most motors run a lot smoother.
Including feedback via encoders would be the ultimate goal for this, possibly with automatic error correction on the fly, an excellent poor man's servo system.
Getting a dev. board together so I will be able to "play" with my new prop chip.
12-11-2006, 10:24 PM
That sounds amazing. I am interested in controlling stepper motors not only for making my own CNC mill, but for drive systems for robotics. Thanks for the code, that should get me started.
Take a look at this:· http://forums.parallax.com/showthread.php?p=620604
You only need a L297 plus L293.