The only required parts are 4 MOSFETs, 1 14-pin IC, and a 100uF decoupling cap. The LEDs, resistors, female headers, and IC socket are just to make the whole thing a little easier to debug and wire up. With the MOSFETs costing about a buck a piece and the IC being $5, the total is very close to $10! Now, while I am using a stepgenie IC for this design (http://www.stepgenie.com/), I have also built the exact same thing using a generic 14 pin microcontroller with my own firmware. Both methods work, however, I already had several stepgenie IC's so I might as well use those and save the other microcontrollers for other projects.
After making the schematic and testing the whole thing on a breadboard I went ahead and made a single-sided eagle pcb that would allow this driver to be made extremely easily on any cartesian machine that has milling capabilities (later versions of mendel??). PCB milling and drilling isn't too hard as long as your machine has the accuracy and rigidity required, but making only a single-sided board simplifies things greatly. The eagle files can be downloaded here: https://sourceforge.net/projects/hydra-mmm/files/Electronics/StepGenie-Stepper-Motor-Driver-PCB/
Another big advantage to designing single-sided boards is that they can easily be prototyped on general purpose pcb boards, which can be purchased at any radio shack or electronics supply store. I heated up my trusty Weller soldering iron and made 4 of the stepper motor drivers. I also added a 5V regulator with a 4-pin Molex input and a mode selector switch for choosing between wave drive, half step, or full torque modes on each driver. Some pictures of my hard work are below
I tested the whole thing with a couple motors and my spare Arduino and it worked wonderfully! The half stepping mode is relatively smooth, especially when running them at a high stepping frequency (~1kHz) which is what we will be using most of the time for the leadscrews used on Hydra.
While the full-blown Allegro based stepper motor drivers that Reprap and Makerbot currently use are surely superior, this design is one that is less expensive and easier to make with everyday tools, which may make it a winner for other hobbyists working on a budget. Let me know what you think in the comments!
what is the max frequency for this stepper driver ?
ReplyDeleteThe stepgenie spec sheet states a maximum stepping frequency of 16kHz. You could likely improve this if desired using your own upper-end PIC microcontroller with a faster clock frequency.
ReplyDeleteNice work!
ReplyDeleteI've managed to build a working single-sided version of the 2.3 stepper driver board, but the components cost is about £20 ($35?), much more than your design. We certainly need other options as makerbot are often overwhelmed by demand!
(http://renoirsrants.blogspot.com/)
The stepgenie link is malformed. (Points to http://www.blogger.com/www.stepgenie.com)
ReplyDelete@bbot - the stepgenie link was updated so it should be working now. While the stepgenie is a complete package that works out of the box, it would be much cheaper to just use your own suitable microcontroller for this and you would have a little more control over the functions and operation. Like I said, I have done this and had some great results. The Hydra-MMM firmware actually supports handling the stepping functions internally so that all you would need are the 4 external MOSFETs hooked up to the Arduino. The Arduino Mega has enough pins that you would probably be able to run 4 or 5 motors this way. Drawback is that you may lose a little processing power if your main processor is handling all the stepping as well. See my earlier posts or download the firmware at my sourceforge page to see how this works. There is a schematic in the zip file that shows how to hook everything up.
ReplyDelete@Renoir - I actually saw your post yesterday about the "single-sided" motor driver and was pretty excited to see others making their own PCBs. That is one of the main goals for Hydra so we will likely be following in your footsteps very soon although I have been working on my own design of an a3982/3983 motor driver using all through hole components :)
How about something like an L6208 by STMicro? http://www.st.com/stonline/products/literature/ds/7514/l6208.htm
ReplyDeleteDigiKey carries them in 24-pin DIP: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-5342-5-ND
Would you say this is this an ok schema for a reprap mendel? at least to start of with?
ReplyDeleteI am looking for a new schema and keep myself away from the 'standard' makerbot electronics.
Later on I will try and upgrade to the pololu boards but they are out of stock! and these stepgenies are available as far as I can see.. And the schema is not that difficult. Just need to add the heater and temp circuit ..
with kind regards
@Andrew - I hadn't heard of that IC before, but it looks like it could definitely be a candidate. I have moved over to a4983 drivers at this point so I probably won't be trying it out, but if you do, let us know how it works!
ReplyDelete@mike - this setup definitely worked well for me starting out with a reprap clone. The hydra firmware I have been working on actually allows you to use 12 MOSFETs hooked up to an Arduino to run the entire X, Y, and Z setup. No stepgenie or intermediate IC necessary. I think that would definitely take the cake as the cheapest stepper drivers possible at about $1 per MOSFET.