Linuxcnc on Raspberry

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09 Apr 2018 05:02 #108640 by InMyDarkestHour
I haven't had any issues with the GUI, if axis was an issue I'd try another option.

Theorectically the BBB could do SPI with the right driver.

I'm not a big fan of the whole distributed way that MK seems to be going, rather have everything on the one machine......seems to be a bit "Makerish" for me.

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19 May 2018 17:51 - 19 May 2018 18:34 #110892 by jmr
Replied by jmr on topic Linuxcnc on Raspberry
Hi
Ozzrob: can You tell what latency did the BBB get as running with latency-test?
Same question to anyone who dealt with RPi. The <200us from start of the thread does not look so exciting, doesnt it?
RPi using external step generation and simple interface might be quite interesting, it is nice to know I can just download the packages now. I will try sometime in the future as there is one RPi in my box.
That board with isa turned out to be athlon xp 2k. I repaired it, and with rtai latency test it was below 1000ns. Using console display, and even pushing keyboard buttons resulted in some spikes. latency-test along with some disk io resulted in max jitter of around 20us. heavy disk IO like with dd makes some spikes... That is with PCI sata card. NFSROOT may be better... That should not be bad if it manages to keep that value - of course without using the AGP or PCI video (similar results). UPDATED: Now i'm doing `cat /dev/urandom | hexdump -C` and THAT is below 20us. Maybe the console is ok and the hdd makes more trouble
From the results page in wiki, it seems not many PC systems went below 10us. Is anything seriously more realtime?
Last edit: 19 May 2018 18:34 by jmr. Reason: typos+update

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19 May 2018 23:05 #110907 by InMyDarkestHour
To tell the truth I haven't run any latency tests with my BBB. I just used an image with Machinekit preinstalled and am using the on board PRU (basically the BBB has 2 separate mcu's that aren't touched by the OS, for those that aren't aware), which gives a kind of hardware step generation, not as good as an FPGA but better than the main CPU doing software step generation.

Best results I've had (below 10K) are
Asus M4A785D-M PRO with an Athlon II x2 250, 4GB ram, Kingston 120GB SSD and on board video.

Asus M2N68-AM-PLUS with an Athlon 64 X2 5200+, 4GB ram, Kingston 120GB SSD and a Radeon HD5450 card.

Asus A8N-SLI/A8N-SLI Deluxe with a Athlon 64 3800+, 4GB ram, Kingston 120GB SSD and a Radeon HD5450 card. (MB & CPU were a dumpster find, have spent the last 5 years running as a file server, I upgraded only cos I wanted to run gitlab)

The first 2 Boards are uATX which better suit my build. Although no ISA slots.

All tests were done with an install of Linuxcnc 2.7 upgraded to 2.7.13. I set the disk up for dual boot, one install with RTAI kernel & and the other with a PREEMPT kernel. The M4A785D-M PRO run just a smidgen under 10K even with the PREEMPT kernel with a servo & base thread. An SSD with 3Gbps or greater SATA port is a game changer. The last two combos with an IDE drive were still well 20K. In all Tests I had sound disabled, which makes a difference and the usual BIOS tweaks.

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02 Aug 2018 11:01 #115394 by SINGH
Replied by SINGH on topic Linuxcnc on Raspberry
please any one help me ..?


i am very tired to findout how to install linuxcnc on raspberry pi 3b+.. i was found so many link and step but all these are not work ,so please any one of them tell me how to install step by step linuxcnc on raspberry pi..


thanks you
best regards
Shailesh singh.

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02 Aug 2018 11:22 #115396 by tommylight
Replied by tommylight on topic Linuxcnc on Raspberry

SINGH wrote: please any one help me ..?


i am very tired to findout how to install linuxcnc on raspberry pi 3b+.. i was found so many link and step but all these are not work ,so please any one of them tell me how to install step by step linuxcnc on raspberry pi..


thanks you
best regards
Shailesh singh.


www.google.com/search?source=hp&ei=4ediW...0i10k1.0.bL-lz2nmYNQ

www.raspberrypi.org/forums/viewtopic.php?t=33809&start=950

Those do work, i did install using those guides.
Now, do you want me to come to India to install it for you ??? :)
P.S.
I was contacted by him twice yesterday via e-mail, and i bet many others were too.

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02 Aug 2018 15:20 - 04 Aug 2018 03:54 #115408 by PCW
Replied by PCW on topic Linuxcnc on Raspberry
Those links are both for Machinekit installations

You _can_ build LinuxCNC from source on a RPI running Raspian, really its no different than any other machine (well except rather slow to build)

You also have to install a real time kernel which is more trouble

LinuxCNC runs reasonably well on a RPI but the OpenGL backplot is painfully slow due to the software OpenGL driver so the backplot would likely need to be disabled in a real system. The hardware accelerated OpenGL driver makes the backplot acceptable but breaks realtime unfortunately.

Edit: it is possible to run a 1 KHz servo thread _and_ have hardware OpneGL acceleration but requires somewhat weird isolcpu settings...
Last edit: 04 Aug 2018 03:54 by PCW.
The following user(s) said Thank You: tommylight

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03 Aug 2018 03:58 #115481 by SINGH
Replied by SINGH on topic Linuxcnc on Raspberry
Dear Tommy


Thank you so much for helping and also for your nice comments....
if you wants to come in INDIA . most welcome there is lots of thing you will enjoy.

thank you so much for help .Grand welcome in india .

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26 Feb 2021 15:16 - 26 Feb 2021 15:20 #200197 by tjtr33
Replied by tjtr33 on topic Linuxcnc on Raspberry
Damn don't ever use the quick reply here
then think 'where's the attachments?
then goto editor to find your entire post has disappeared.

Hello
I have 53.7us latency using RPi3B with
latency-histogram --base 80000 --servo 1000000
then adding 4 glxgears
then walking away until the next morning.
At 80us period, less 53.7uS max base latency,
I have 26.3uS to do all the step timing.

I use TB6600 ( with the 'upgrade Toshiba 190 chip )
and the step timings I use are
steplen 2000 stepspace 3000 dir-setup 5000 dir-hold 5000

I use double step and use reset-time of 5000

I use my own hal_pi_gpio which allows reset pins

I use a Sable 2015 machine and it has 200step/rev motors and 1.5mm pitch leadscrews
That makes for 0.0075mm step size at full step.

An 80uS base period makes for 12500 steps per second
at .0075mm/step, thats 93.75mm/second and 5.625meters/minute

Its TOO fast for my hardware :-)
I am very happy.

tomp
Attachments:
Last edit: 26 Feb 2021 15:20 by tjtr33.

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15 Apr 2021 13:01 #206002 by tjtr33
Replied by tjtr33 on topic Linuxcnc on Raspberry
Hello,
I just got an email about a new possibilty with RPi OPi BPi etc.

A control board originally for reprap machines,
has a linuxcnc driver module.

The pcb necomes a hardware stepgen
The pcb has an LPC1768/9 chip.
The communication is SPI so very little wiring between Pi and LPC
( literally, the wires should be short in length and few in count )

here's the docs
remora-docs.readthedocs.io/en/latest/

and here's the src
github.com/scottalford75/Remora

A posible board for this is
github.com/makerbase-mks/MKS-SGEN_L-V2
There's some argument about opensource-correctness for that pcb.
I have not found the bottom of the argumants yet.

I did find these makerbase people have quite a few interesting repo's
( interesting to cnc people )

The original smoothieboard version 2 and version 1 are seen at
smoothieware.org/

The idea seems to be
like the PICnc effort,
a cheap hardware stepgen using SPI.

TomP

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