BrendaEM
Posts: 3
Joined: Sat Mar 31, 2018 5:10 am

LinuxCNCPi - and Board

Sat Mar 31, 2018 5:32 am

I don't get it. I should think the the PI would be a darling computer to use for LinuxCNC, though there's no official RasperianCNC distro.

Apparently, someone has the kernel all patched up, already.
http://www.frank-durr.de/?p=203

It would be cool it there were a standard IO board for CNC and Pi use which would include:
* A Realtime clock and battery, which are necessary as it's not a good idea to have a CNC cutting machine facing the web in most instances.
* Transistors to operate opto-isolators to protect the I/O.

It looks like excluding the two-wire pins, and the serial port pins, there are 22 remaining.
I6 outputs and 7 inputs?

Are there some other RPi pin conventions I am missing?

Which is better than a parallel interface, is it not?

Thanks for any input. This looks like one of the coolest things I would want a Pi for.

MrGreg
Posts: 65
Joined: Sun Jun 10, 2012 7:25 pm

Re: LinuxCNCPi - and Board

Sun Apr 01, 2018 11:26 am

That's quite a "Wish List"

If you have not already seen this, A good place to start.......
viewtopic.php?f=37&t=33809

The above setup runs fine for me, although not quite meeting your prescriptive ideal.
Currently only Jessie supported out of the box.
Couple of additional links
http://www.machinekit.io/
http://www.machinekit.io/docs/getting-s ... -packages/

You might find this of additional info / interest
viewtopic.php?f=117&t=206747

It's a good deal of work to get Linuxcnc/Machinekit running. AFAIK there is no magic board / turnkey solution you can buy.

Alternativly
GRBL is a simpler solution but has less functionality then Linuxcnc/Machinekit. It does work well with a Pi3
If your needs are simple. like a desktop mill or similar, this pretty much works out of the box.
The RPi provides some of the brains and a nice GUI. The Arduino does the stepgen & output
https://github.com/gnea/grbl
You will need a sender for the Pi. This one works OK
https://github.com/vlachoudis/bCNC

There are other solutions if you research

BrendaEM
Posts: 3
Joined: Sat Mar 31, 2018 5:10 am

Re: LinuxCNCPi - and Board

Mon Apr 02, 2018 2:20 am

Thanks for the links @MrGreg.

Well, the wish list isn't all wish list.

I do want an somewhat official Raspberry Pi, LinuxCNC distro/variant, using one of the two real-time patches done.


Though, what I wanted was feedback, as far as pin assignments.
I can make a board for myself, but I don't get why there aren't others, well one in the works.

GRBL is interesting, but it's not flexible, not really modifiable because they have used every byte, and also it does port writes for speed, and that's not too transportable. Although there are comments, the code appears organized inscrutably. It would be easier for me to write a whole new G-code interpreter from Bresenham's Line Algorithm, than make surgical changes in what they have done, but I have too many irons in the fire, like this: http://forum.arduino.cc/index.php?topic ... msg3213804

I don't understand what Machinekit is for. I see parallel port assignments, hardcoded at that. This was supposed to be ARM? I've seen more Beaglebone posts about it, not much about the RPi.

On one thread you pointed me to, there's 41 Pages of posts, so (shrugs shoulders) I guess no one is interest in running a CNC machine from a Raspberry Pi.

fruitoftheloom
Posts: 17838
Joined: Tue Mar 25, 2014 12:40 pm

Re: LinuxCNCPi - and Board

Mon Apr 02, 2018 4:52 am

BrendaEM wrote:
Mon Apr 02, 2018 2:20 am
Thanks for the links @MrGreg.

Well, the wish list isn't all wish list.

I do want an somewhat official Raspberry Pi, LinuxCNC distro/variant, using one of the two real-time patches done.


Though, what I wanted was feedback, as far as pin assignments.
I can make a board for myself, but I don't get why there aren't others, well one in the works.

GRBL is interesting, but it's not flexible, not really modifiable because they have used every byte, and also it does port writes for speed, and that's not too transportable. Although there are comments, the code appears organized inscrutably. It would be easier for me to write a whole new G-code interpreter from Bresenham's Line Algorithm, than make surgical changes in what they have done, but I have too many irons in the fire, like this: http://forum.arduino.cc/index.php?topic ... msg3213804

I don't understand what Machinekit is for. I see parallel port assignments, hardcoded at that. This was supposed to be ARM? I've seen more Beaglebone posts about it, not much about the RPi.

On one thread you pointed me to, there's 41 Pages of posts, so (shrugs shoulders) I guess no one is interest in running a CNC machine from a Raspberry Pi.

https://github.com/Nikolay-Kha/PyCNC

https://wiki.protoneer.co.nz/Raspberry_Pi_CNC

The ethos is RPF is education and learning, by DIY you are fulfilling that ethos....
Adieu

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Lob0426
Posts: 2197
Joined: Fri Aug 05, 2011 4:30 pm
Location: Susanville CA.
Contact: Website

Re: LinuxCNCPi - and Board

Mon Apr 02, 2018 6:00 pm

There is the MegaPi board. It uses the Arduino 2560. More storage, more memory, more eeprom. Processor speed is the same as Nano/UNO. GRBL has moved to the Mega2560 exactly for the reasons you stated. In fact they are going to 32bit ARM. The actual connection is serial only pins. It can operate without a RasPi or as a Hat on a Raspi. The other RasPi "CNC" boards use a 328P. GRBL was only 3 axis I do not know if they have added axis. The 2560 has open I/O to have more axis.

I found on the laser machines the 2560 was smoother and more accurate than a Nano using GRBL. Most likely from the larger buffers available on the 2560, but also from more free memory.

I have not used the MegaPi.

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