Raspberry Pi 4 Tutorial - fatal error

John, please make an img file where you did all this stuff to your OS and send it to me so I can flash it to my microSD card. The tutorial you posted is not working right for me and I'm at the point to where I am about to throw my Raspberry Pi 4 across the room in frustration. Im a Windows person, not a Linux guru.

Dear John,

just wanted to say a big thanks for the tutorial. I followed it to the letter and finished today with a working machine. To note that I used the just released Raspberry Pi OS, without any issues.

Thanks - excited to now configure the Mesa Card and make some motors turn !
Pierre

BigJohnT wrote: I'm working on a tutorial for the Raspberry Pi 4B to run Mesa Ethernet cards but to my surprise the latency is much better than I thought at <30us. Anyway anyone that has a Rpi4 and wants to run through the tutorial and see if I have anything that is absolutely not clear for a Linux beginner please do.

I'm using Rasbian 10 patched with the preempt rt kernel LinuxCNC Uspace and a blank slate window manager OpenBox.

As usual the Uspace tutorials are here: gnipsel.com/linuxcnc/uspace/

JT

Dear John,
also me, just wanted to say a big thanks for the tutorial, Thanks!

just today applied, almost fine, then I came here and struggle

pi@raspberrypi:~/emc $ sudo apt-get update
pi@raspberrypi:~/emc $ sudo apt-get dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
pi@raspberrypi:~/emc $ debian/configure uspace
successfully configured for 'uspace-Raspbian-10'-'uspace'..

pi@raspberrypi:~/emc $ dpkg-checkbuilddeps
dpkg-checkbuilddeps: error: Unmet build dependencies: debhelper (>= 6) dh-python libudev-dev python-yapps tcl8.6-dev tk8.6-dev libreadline-gplv2-dev asciidoc (>= 8.5) dblatex (>= 0.2.12) docbook-xsl dvipng ghostscript graphviz groff imagemagick inkscape python-lxml source-highlight texlive-extra-utils texlive-font-utils texlive-fonts-recommended texlive-lang-cyrillic texlive-lang-french texlive-lang-german texlive-lang-polish texlive-lang-spanish texlive-latex-recommended w3c-linkchecker xsltproc asciidoc-dblatex python-dev python-tk libxmu-dev libglu1-mesa-dev libgl1-mesa-dev | libgl1-mesa-swx11-dev libgtk2.0-dev gettext intltool autoconf libboost-python-dev libmodbus-dev (>= 3.0) libusb-1.0-0-dev desktop-file-utils yapps2

next day:
I have learned to work careful enough when using ssh - not always terminal prompt was within client side, so today I coul'd finish successfully, many thanks for the tutorial!

@BigJohnT even a BIG john Thanks from me!

I am a new bee on CNC and all stuff to do with that
and my English is humbl.
please bear with me.

Ich have managed to install the RT kernel and LunuxCNC on my Raspberry Pi 4B.

The only thing I have done so far is running the Jitter Test.

In the first run I got "Base Thread" over 60000 (scared) the run was about 5 minutes.

After pressing "reset statistic" the "Base Thread" jitter was about 20000 and in the folowing it was repeatable.

I found statements that 20000 "Base Thread" jitter is good enough for Stepper Motors.
(here in German: lonnox.de/installation.htmlhttps://lonnox.de/installation.html )

So my main question is

What "Base Thread" jitter values other user have with Raspberry Pi 4B and RT Kernel ?

On a RPI4 there is no use for base thread, so forget about it.
The servo thread should be at acceptable levels, the step pulses will be generated buy another card like Mesa 7i92 or 7i96 or 7i76E.

Ok. Thank you for clarification!

That opens a new Question...

What Max jitter (ns) do we need with Servo Thread?
What Max jitter (ns) do others have on with Servo Thread?