Raspberry Pi 4

I am all for improvements. Checked the link. We both use the RaspberryPi kernel patched with the official Preempt RT patches. The link uses CustomPi, I used standard raspbian. My immediate thought is that there should not be much of a difference.

One thing I know is that the sd-card I used during these tests was amazingly slow. I will retest early next week with a much faster sdcard, perhaps that slowed things down. Apart from that I can just say I was hoping for a better result and I am willing to test good leads.

Here is a little q&d-howto to install a rt-patch :

erste.de/raspi4-RT-kernel-howto.html

I will also document the needed steps for compiling the linCNC-source on
the RP4 the next days.

andypugh wrote: Try here; github.com/guysoft/RealtimePi

OK, as far as I can see the images there do not boot the 4 into a realtime kernel, so are no help at all.

What does uname -a say ?
Have some RPI 3B and i did download that last night but did not have time to test yet.

compile, latency-test and start of lincnc 2.9 on a PI4 :

erste.de/raspi4-RT-kernel-howto.html#compile_linCNC_on_Raspi4

one axis test: lincnc 2.9 on RPI4 with
Linux raspberrypi 4.19.50-rt22-v7l+ #2 SMP PREEMPT RT Sat Jul 13
09:21:03 BST 2019 armv7l GNU/Linux

a stable 5kHz step/dir signal is generated.
as a quad-signal 10kHz should be possible.

further tests in a 4-axis system will follow.