RPI4 Raspbian 64 bit & LinuxCNC

There have been issues reported with both 2GB and 8GB versions of the Pi4

[strike]Apparently some versions of the Pi do not have an SPI ROM for the USB chip.

This requires a fix in the kernel.

I have just now uploaded a new Pi kernel to the LinuxCNC repository which should fix the issue. It should also make for a smoother installation.

I would recommend the instructions here as the easiest way to get LinuxCNC and a suitable kernel on an existing Pi.

linuxcnc.org/docs/2.8/html/getting-start...lling_on_raspbian_10 [/strike]

The image linked above is 32 bit, not related to this thread.

Thank you for working on this!

The link refers to a 32bit install this thread is for 64bit install

tjmarch wrote: The link refers to a 32bit install this thread is for 64bit install

Sorry, yes, I failed to notice that.

I was trying to go through the several threads that were saying that the LinuxCNC Pi Images that I had built had no USB on the new versions, and seem to have posted to an inappropriate thread.

[strike]Thank-you Elovalvo
I am using RPI4 4GB, with your hard work I am able to use my Raspberry PI camera with linuxcnc without latency problems. With the 32bit version this was not posible. Your version also is successful for stepping with gpio pins. Again Thank-you!!!![/strike]

The kernel is non-real-time that is why my cam works, is this ok to use? Kernel must have been configured as low latency but not Full Real Time option before compile. Elovalvo maybe you could give info on which Real Time option, General -> Preemtion Model was selected before compiling this kernel

I confirm that the version in this link
forum.linuxcnc.org/9-installing-linuxcnc...xcnc?start=10#181585
was compiled with the Full Preempt option.

Maybe tjmarch made an update that changed the contents of the /boot/config.txt file.

What answer do you get to the terminal command: 'uname -a'?
It should be 'Linux raspberrypi 5.4.80-rt44-v8+'

Want a small RPI4 inside your QTplasmac controlcabinet

-RPI4 uses OPENGL ES
-QTVCP is OPEL GL
(to my understandings)

* I struggled way to long with trying to install / modify my plasmaC to be the new cool qtPlasmaC, only to find out it is not supportet by the RPI4

The problem is when you invoke Linuxcnc or latency-test form the command line. It says it is running Posix non real-time. If it were compiled with fully RT kernel option it would say running real-time. I suspect it was compiled with low latency desktop option. The full RT kernel option is not a available option when compiling some newer kernels. If it were compiled with low latency decktop I am just wondering if this option is good enough to use. And to note I have not made any changes to the /boot/config.txt file and uname -a still reports a RT kernel label which is just a label that is added by the RT patch for the kernel being compiled