RPI4 Raspbian 64 bit & LinuxCNC

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11 Sep 2023 20:58 #280497 by tommylight

I have run steppers on an Arduino this way.......   
.....MOst motors give up at 750 rpm

Arduino Uno, Nano etc, the small crappy ones can do 1MHz when using interrupts.
But they do nothing else, so does not apply to RPI.
Most small motors, bigger ones will probably stall at 750RPM, depending on the drive and voltage being fed, and the inductance of the motor.

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11 Sep 2023 21:32 #280502 by rodw

I have run steppers on an Arduino this way.......   
.....MOst motors give up at 750 rpm
Arduino Uno, Nano etc, the small crappy ones can do 1MHz when using interrupts.
But they do nothing else, so does not apply to RPI.
Most small motors, bigger ones will probably stall at 750RPM, depending on the drive and voltage being fed, and the inductance of the motor.

Tommy, the comments about the arduino has not been my experience driving steppers with arduinos.The interrupt is happening regardless so there is no performance hit if you code it right.  I agree with the 750 RPM.

The principles apply to any CPU, more so to the Pi which has the GPIO ports and a 64 bit CPU.
 

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18 Sep 2023 11:59 #281070 by rodw
I am just finishing a final build after the release of  a new real time kernel patch yesterday
You can find it here in a new thread
forum.linuxcnc.org/9-installing-linuxcnc...-raspberry-pi-4b-400

I will also update my repository as I've included  a few cool Linuxcnc specific switches in userdata.txt for those who want to build different branches with/without the docs.

Man the docs take forever to build!

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19 Sep 2023 21:08 #281194 by rodw
The Pi has a new kernel 6.54 and also today a RT patch has become available for it
New commit number is: fad58933544bb2a7b7db92847c25c79a83171fa6

More work!
The following user(s) said Thank You: iforce2d, mwiktowy

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13 Nov 2023 21:31 #285314 by mwiktowy

On an x86 machine an apt upgrade right now will only update security patches . As its so new, there is not much else. But it will get updates to linuxcnc. I just did a new bookworm install  and there was nothing to upgrade.
If you did it on buster, there has no doubt been some point releases 9.1,9.2 etc since linxcnc made their ISO. So far in Bookworm, we have only had a 12.1 update. Remember I said it was locked to new packages?

Once Linuxcnc finally releases 2.9, It will sort out becasue we don't upgrade our versions often either.

And it is possible to do an apt full upgrade after changing sources so you can upgrade from Buster to Bullseye and then to Bookworm...
I have done this but its almost quicker to reinstall from scratch.

I am hoping this imager will also publish the linuxcnc debs so if run in an automated buildbot it could update the imager and the linuxcnc debs.
IN any case, its possible to pin repositories and pull linuxcnc from trixie or backports while running Bookworm
 

Now that RPi LinuxCNC 2.9.1 has been released, I have imaged it onto a USB stick and have configured networking on it. Sorry if am misunderstanding the conversation here but, is it safe to update/upgrade packages via apt/synaptic or will there eventually come a kernel update that will clobber the RT kernel? I saw that you had your own repos set up to offer updates. Is there something that I need to do to make those the preferred repo?

I ask since I suspect that is possibly what happened with an earlier version of a pre-2.9 build that I was using. It worked perfectly for a while and then an update or two later, the updates solved some graphical issues but it also developed issues where it would just e-stop mid-GCode without warning or error.

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13 Nov 2023 21:41 #285315 by rodw
For the pi it may not be a good idea to do an upgrade becasue it could cause the kernel to rolll forward ahead of the PREEMPT_RT kernel we build in the installer. and this could break the RT patches. (Which happened to me when I first started to build this installer)

Now linuxcnc has debs available on its own repo, I need to rework the installer so it is more upgradable than it is currently.
The following user(s) said Thank You: mwiktowy

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14 Nov 2023 08:36 #285350 by elovalvo

The Pi has a new kernel 6.54 and also today a RT patch has become available for it
New commit number is: fad58933544bb2a7b7db92847c25c79a83171fa6

More work!

in this link you will find the description of my experience on the recent Raspbian 12

forum.linuxcnc.org/9-installing-linuxcnc...aspberry-pi-5#285240

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14 Nov 2023 10:22 #285359 by rodw

The Pi has a new kernel 6.54 and also today a RT patch has become available for it
New commit number is: fad58933544bb2a7b7db92847c25c79a83171fa6

More work!
in this link you will find the description of my experience on the recent Raspbian 12

forum.linuxcnc.org/9-installing-linuxcnc...aspberry-pi-5#285240

As I noted in your thread, advancing past the PREEMPT_RT 6.1.54 kernel is not recommended because none of the later kernels have been merged into the Raspberry mainline kernel code. 

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