LinuxCNC on Raspberry Pi 4

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4 years 1 month ago #252532 by armin-f
Replied by armin-f on topic LinuxCNC on Raspberry Pi 4
@rodw
Thank you for the hint.
Can you please tell me, what version of LinuxCNC the package is?
And do you know, if it works with PlasmaC?

Since I expect, to need some compilation to modify PlasmaC for oxy-fuel cutting, and to write a new HAL driver, to directly use the RPI gpio-pins to read the encoders and drive servo amplifiers, I'll not be able to avoid compilation.
Still it is good to know, that someone was able, to get 64bit working on bookworm.
If the python-tk package is based on python3 there, this may be the critical difference for a successful configuration of LinuxCNC.

Yesterday I was able to get an old BARCO encoder to work with lab-power supplies and an oscilloscope, so I believe, that this route makes sense for me.
I believe, that it's best, to use interrupt service routines to process the state changes of the encoder channels. While it may be possible to poll the state in the fast thread, it's less reliable and a waste of resources. Turning the encoder by hand yesterday, I got pulse frequencies in the kHz range. It also was apparent, that the pulses don't have a 50% duty cycle, nor is the A<->B offset half the pulse distance. It's more like 30%. So one may get some additional precision, by accounting for that in an offset table that contains the true distances of all state transitions relative to some "master edge".

I'm not worried about the GUI right now - I might even run the machine headless, since it's out in the open under a canopy.

Kind Regards, Armin

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4 years 1 month ago #252557 by rodw
Replied by rodw on topic LinuxCNC on Raspberry Pi 4
Go with Debian Bookworm, follow the instructions and you should end up with 2.9 so QTPlasmac is included.
I have not done this for a few months.

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4 years 2 days ago #255424 by dannym
Replied by dannym on topic LinuxCNC on Raspberry Pi 4
OK I was excited to see this was possible, I downloaded linuxcnc-2.8.2-pi4-arm64 and put it on the SD for my RPi 4 8GB. Got that "the board requires newer software" message reported earlier.

What's the status? Is there a reliable image? Can we reliably keep the latency down enough for one with a Mesa card across ethernet?

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4 years 2 days ago - 4 years 2 days ago #255425 by dannym
Replied by dannym on topic LinuxCNC on Raspberry Pi 4

From one of the developers over the weekend

On 9/14/22 15:35, Rod Webster wrote:
>
> [url] raspi.debian.net/tested-images/ [/url]
 

 
I tried the top build "022.08.0812 (Bookworm)44 (4GB)"
On my 8GB RPi 4.  I see the boot log scrolling past then the screen loses HDMI signal.  The red LED on the RPi 4 went out, only a blinking green LED left.  Should I start trying other builds?
 
Last edit: 4 years 2 days ago by dannym.

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4 years 1 day ago #255465 by dannym
Replied by dannym on topic LinuxCNC on Raspberry Pi 4
OK went for an older build, 2022.01.21, and it does boot.

I'm confused, I thought the hardware was so standard it should yield consistent results. Could it be that the 8GB is somehow not going to run the one tested on 4GB? I can't say.

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4 years 1 day ago #255479 by tommylight
Replied by tommylight on topic LinuxCNC on Raspberry Pi 4
Not standard anymore, even the same versions are not the same, from what i read, from version 1.5 and above even the official image has issues.

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