Raspberry Pi 4

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23 Jul 2019 16:06 #140308 by andypugh
Replied by andypugh on topic Raspberry Pi 4

Buster had a surprise. I had done a RealtimePi conversion based on buster rc1. Realtime was very good, but then a day or so after the release announce, came a good sized update including the video libs. Took full screen glxgears from about 1.7 fps to 19 fps or above, but that also removed the rt-preempt kernel, so latency went in the crapper.


There was an update to the 4.19-y-rt Raspbian today but the RealtimePi guy is away from home until the end of this week. So I imagine realtimepi will be working again some time after that point.

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23 Jul 2019 16:06 #140309 by andypugh
Replied by andypugh on topic Raspberry Pi 4

Buster had a surprise. I had done a RealtimePi conversion based on buster rc1. Realtime was very good, but then a day or so after the release announce, came a good sized update including the video libs. Took full screen glxgears from about 1.7 fps to 19 fps or above, but that also removed the rt-preempt kernel, so latency went in the crapper.


There was an update to the 4.19-y-rt Raspbian today but the RealtimePi guy is away from home until the end of this week. So I imagine realtimepi will be working again some time after that point.

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23 Jul 2019 16:37 #140313 by Gene1934
Replied by Gene1934 on topic Raspberry Pi 4
I'll check into git and check the timestamps.

Thanks Andy.

Cheers, Gene Heskett

Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <geneslinuxbox.net:6309/gene>

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23 Jul 2019 17:04 - 23 Jul 2019 18:03 #140315 by Hakan
Replied by Hakan on topic Raspberry Pi 4
There was an update. I have tested it, works fine. Go for the rpi-4.19.y-rt version.

As far as I understand it there are a few, specific python libraries that are not included in buster anymore. They are the problem, not python 2.7 really. marc.info/?l=debian-devel&m=146974136510682&w=2

Gene, I read your journey. I invested in the BeagleBone Black approach years ago, made own caps and what now. In the end the platform couldn't deliver. Too slow graphics, too limited memory. Unusable. But the RPi4 is another thing. Here it actually works. I have compiled both the kernel and linuxcnc on the RPi4 with 4 GB memory with just 100 kB swap that came with it.I can run the lathe in the same way as the Intel PC (except lathemacros then). I definitely see the RPi4 as a possible platform.
Last edit: 23 Jul 2019 18:03 by Hakan.

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25 Jul 2019 09:52 #140519 by wicki
Replied by wicki on topic Raspberry Pi 4
Here are all steps to install OS, RT-kernel and linuxCNC on a blank RPI 4:


erste.de/linuxCNC_raspberry_PI4.html

Config/Usage of GPIO will follow....
The following user(s) said Thank You: kostas, seuchato

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25 Jul 2019 10:14 - 25 Jul 2019 10:15 #140520 by andypugh
Replied by andypugh on topic Raspberry Pi 4
It is probably easier to use the pre-patched raspbian kernel:
github.com/raspberrypi/linux/tree/rpi-4.19.y-rt
git clone https://github.com/raspberrypi/linux.git
git checkout 4.19y-rt

Or there is a pre-built LinuxCNC + preempt RT SD card image here, but please only download this if you have a Pi4 and intend to use it, it's a big image and I am concerned about the server bandwiidth.
www.linuxcnc.org/dists/buster/2.8-uspace/
Last edit: 25 Jul 2019 10:15 by andypugh.
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25 Jul 2019 13:15 #140527 by wicki
Replied by wicki on topic Raspberry Pi 4
> Config/Usage of GPIO will follow....

usage of hal_gpio is now also described here

erste.de/linuxCNC_raspberry_PI4.html

but then, GPIO does not work any more.... :-(
also "gpio toggle 0" does not toggle a pin :-(

maybe a bug in the bcm-lib?
I will check this tomorrow....



> It is probably easier to use the pre-patched raspbian kernel:
> github.com/raspberrypi/linux/tree/rpi-4.19.y-rt

thats easier,yes - but the above howto is written for thoose who
would like to do it by own hands.... ;-)

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28 Jul 2019 13:27 #140800 by Hakan
Replied by Hakan on topic Raspberry Pi 4
Yesss! Got lathemacros working (unmodified).
I got hold of an older version of rsvg (for Pi 3 or older, I suppose) from here
packages.debian.org/stretch/armhf/python-rsvg/download
dpkg --install <package>
then got an error on "Xlib" not found.
apt install python-xlib
and it is all working! Yess, that was the final piece that was missing.

I did some manual turning yesterday. It all works fine. My normal setup is
a quick Intel Core i3 6100 on this machine. RPi4 doesn't *feel* quite as responsive, but
it is just the occasional microdelay. I press a key on the gamepad and it takes
just a tiny different amount of time. The screen response 1920x1080 with
touchscreen is absolutely acceptable. Not as quick as the Intel though,
but workable no problems.

Now when LatheMacros works I will have the RPi4 on the lathe and see how it goes in
long term.

I looked at the output from linuxcnc.
There are some ten of those
task: main loop took 0.024097 seconds
during GUI buildup. When gmoccapy is up and running
and the machine is ready so to say there are no more such messages.

If I let it sit idle, there is some screensaver that shuts everything down,
including networking so that need to be fixed. Probably easy, I will not
dig into that direction.

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28 Jul 2019 13:31 #140801 by tecno
Replied by tecno on topic Raspberry Pi 4
Very interesting HÃ¥kan, good work!

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29 Jul 2019 11:32 #140880 by Hakan
Replied by Hakan on topic Raspberry Pi 4
A video that try to show linuxcnc on the RPi 4 to give a general feeling of the speed and so on.

The following user(s) said Thank You: Mike_Eitel, kostas, bjames28, tommylight, tecno

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