LinuxCNC Installation

Discussion of linuxCNC (formerly knows as EMC2)
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LinuxCNC Installation

Post by levlandau2 » Sat Mar 02, 2013 5:25 pm

So I got around to installing LinuxCNC. I used an old desktop with a parallel port. It was single core and I tried both the Ubuntu 10.04 and 8.04 distribution of LinuxCNC. Surprisingly the 10.04 distribution worked quite badly and had really high jitter when running the latency test. The LiuxCNC forums suggested that the 10.04 distribution has a lot of optimization in the kernel for multiple cores so it may not be a good choice for a single core processor.

Another challenge was getting the parallel port working. Apparently the parallel port I had was based on 3.3V logic, while typical stepper drivers use 5V logic. I couldn't figure this out for a while, but fortunately the pulolo drivers can use either 3.3V or 5V logic, so everything worked out in the end. Unfortunately now I need to find a 3.3V power source.

I am using the buildlog stepper shield and a DB25 breakout board. Right now things are connected together with wires, and it is not the most elegant solution. Does anyone know if there are circuit boards which allow connecting the build log stepper shield to a parallel port in a cleaner way?

Anyway, LinuxCNC seems interesting. Took me probably 6-8 hours of work to get it working.

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Re: LinuxCNC Installation

Post by ThatOtherGuy435 » Sat Mar 02, 2013 8:04 pm

After I get my buildlog stepper shield, I had planned on trying to design a DB25 breakout that would fit under the shield in place of the arduino, and get a couple PCBs made up.

Given that I don't even had the shield yet, it may be a few weeks, but if you're not in a rush.... :P
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Re: LinuxCNC Installation

Post by cvoinescu » Sun Mar 03, 2013 12:36 am

Bart Dring also designed a stepper board that takes Pololu drivers and input from a parallel port. Or, if you want to keep using the stepper shield, there's a thing called ScrewShield, which does nothing electrical but helps you connect wires.
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Re: LinuxCNC Installation

Post by madmanmoe » Mon Mar 04, 2013 3:19 pm

I just compared Bart's 4 axis stepper driver designs with the stepper shield and then built myself a little board to fill in the gaps.
On my interfacing board all I did was route the stepper shield pins to the correct parallel pins (via an optocoupler, but you can get away without this). I also threw in a 5V regulator to supply the logic.
I don't think anyone makes a specific board yet, I was pretty happy with how mine came out, unless it stops working I'll just leave it on stripboard.

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