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LinuxCNC with parallel port breakout board and Pololus?

Posted: Tue Apr 29, 2014 11:25 pm
by Camel
I'm looking to try LinuxCNC with my Shapeoko.

Anyone have experience, or any info, on using one of these cheap Ebay Parallel port breakout boards with four Pololu DRV8825 stepper drivers?

http://www.ebay.com/itm/Upgraded-5-Axis ... 6387&rt=nc

Re: LinuxCNC with parallel port breakout board and Pololus?

Posted: Wed Apr 30, 2014 1:02 am
by Enraged
I bought a 4 axis parallel port driver board, but never got it running due to lack of parallel port on my computer (too new). Now I'm working on setting up a Beaglebone Black with a BeBoPr++ cape and pololu drivers. There are a few people working on this setup, might be a good option if you don't have a parallel port equipped computer.

If you are interested you can read more about it here: http://blog.machinekit.io/

Re: LinuxCNC with parallel port breakout board and Pololus?

Posted: Wed Apr 30, 2014 2:03 am
by CalebPeters
LinuxCNC is the bomb, and I recommend it in all its forms.

It just so happens that what you're proposing isn't too far off what I've implemented in my own build. I don't know much about that particular breakout board, but I have a pretty healthy amount of information on my build log that might help you out.

Here's a rough diagram of my wiring setup. Below is a fairly high resolution image of the diagram, and also a link to the Visio file of the diagram itself.

Credit for the images of the C10 breakout board and DRV 8825 boards should go to CNC4PC.com and pololu.com

http://bobdylansays.com/wp-content/uplo ... ematic.zip

Image

Re: LinuxCNC with parallel port breakout board and Pololus?

Posted: Wed Apr 30, 2014 9:19 am
by cvoinescu
That looks good. The only changes I would make to that schematic are:
  • Use the 5 V from the breakout board. Your board comes with a funky USB cable to tap 5 V from the PC, so you don't need an external supply.
  • Make sure all GND pins of the drivers are tied together. The diagram shows the motor power supply connected to each stepper driver, but, in reality, there's a single supply, and its negative terminal should also be connected to the GND of the breakout board.
  • Connect pin 14 (Enable) to the #ENABLE inputs of all drivers.
  • To use A4988-based drivers (the black ones), you have to connect the 5 V pin of the drivers to 5 V (on the DRV8825-based chips, the same pin is labelled #FAULT, and can be left unconnected, or connected to 5 V, doesn't matter). It's a good idea to add an 100nF ceramic capacitor between 5 V and GND right next to each driver.
The capacitors should be aluminum electrolytic (the most common kind), and not of the low-ESR type. 47uF per driver is enough, because you have four of them in parallel anyway, but 100uF doesn't hurt anything. They should be placed close to the drivers.

Re: LinuxCNC with parallel port breakout board and Pololus?

Posted: Thu May 01, 2014 1:48 am
by Camel
Thanks for the info.

I have an old PC with a parallel port and the stepper drivers, so really a few buck on an Ebay parallel port breakout board and a cable makes for a very cheap way to try LinuxCNC.