Zenbot/Gecko/LinuxCNC?

The first board I would try is a BeagleBone Black I've got laying around here. Some might say that it isn't fast enough, and maybe they are right, but I'm willing to give it a go given that what you call the base-thread would be running on the Mesa instead of the Linux CPU. My router is a pretty basic stepper setup other than the mirrored x motor.

I'd just hook up external monitor, mouse and keyboard. I've done this before and it runs the standard Linux UI stuff just fine.

If this board isn't fast enough, I can look at something else.

Machinekit is a fork of LinuxCNC which seems to centre on the Beaglebone Black. They actually use the PRU for step generation. They tend to rely on a remote PC to render the GUI, the BBB hasn't the graphics power to do that (well) itself.

That's a pretty big saving on hardware, too.

But I don't know much about the project since they forked off.

Thanks for the tip.

I'm having trouble making sense of the GUI comment. I've never used LinuxCNC, but the UI on Mach3 doesn't do anything fancy at all. It's not like they are doing realtime 3D rendering or anything like that. On my current system, the 3D simulation of the machine paths is done ahead of time in the CAM tool (Fusion360).

I can easily afford a 7i92 for $89, especially if it offloads the CPU. But I did read in a forum post somewhere that you need a special distro of Linux to use LinuxCNC with Mesa ethernet interfaces, with a realtime kernel. I could make much sense of that, but there it is.

PRU = ??. Not familiar with the term.

jandyman wrote: I'm having trouble making sense of the GUI comment. I've never used LinuxCNC, but the UI on Mach3 doesn't do anything fancy at all. It's not like they are doing realtime 3D rendering or anything like that.

Some of the LinuxCNC UIs do 3D rendering of the toolpath using OpenGL, and the graphics system on the BBB doesn't excel at OpenGL.
You can use a low-graphics UI and it all ought to be OK.

I can easily afford a 7i92 for $89, especially if it offloads the CPU. But I did read in a forum post somewhere that you need a special distro of Linux to use LinuxCNC with Mesa ethernet interfaces, with a realtime kernel. I could make much sense of that, but there it is.

LinuxCNC has used RTAI as the realtime layer for a long time (decades) but there is no real-time access to ethernet in RTAI. A newer realtime system (preempt-rt) does allow realtime access to ethernet, so that is what needs to be used there.

The simplest way to get something a lot like LinuxCNC running on a BBB would be to download a pre-built image from the Machinekit folks.
But for any problems you would need to ask them, not us.

PRU = ??. Not familiar with the term.

Programmable Realtime Unit. It is a part of the BBB that can do pretty much the same things as a Mesa FPGA card does, but is onboard rather than extra.

The BBB isn't _that_ much smaller or cheaper than a Mini-ITX x86 motherboard, though.

First, thank you for your time. You are really helping me gain an understanding of the terrain. I'm an experienced firmware engineer and DSP guy, so I understand all the concepts just fine. But learning the specifics is really helpful.

I'm completely open minded to a Mini-ITX x86 motherboard. But are you including the cost of CPU and RAM and diskless storage? If so, please send some links! When I've looked before, it's added up quick.

Based on what you saying about the BBB PRU, I'll go learn something about that. Since it's onboard, I would presumably be able to use RTAI and that would be more conventional. There is a lot to recommend the road more travelled. My primary goals here are a) make the machine control part of the machine rather than being a separate laptop or desktop PC and b) keep it affordable. Otherwise I would just go with UCCNC and hold my nose about Windows and its bloat and virus proneness and cost.

About the only graphics I need would be to render the machine path in an overview once (no animation). That's what Mach3 does and it is handy.

No eBay APP ID and/or Cert ID defined in Kunena configurationI think that Machinekit use Xenomai. (a third alternative realtime system). They already have PRU step generator drivers as part of their image. That driver is not included with LinuxCNC.

The last system I set up used a board similar to this:
www.mini-itx.com/store/~JNF9T-2930
(runs off 12V power, so no PSU needed, as you probably have that in the case) and uses something like this: for the storage. Then you just need a DIMM.
So yes, it is more expensive than a BBB, by a factor of 2.

I just put the MB bare in the electronics box . I removed some selenium rectifiers and had plenty of room.