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LinuxCNC and RTAI

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Post time 2016-10-14 18:32:36 | Show all posts |Read mode
Hi, people!

I have an idea to setup a linuxCNC on OrangePI to control a 5-axis machine via GPIO.I've read that there was positive experiance in building the linuxCNC for ARM (but didn't see any details in the internet yet).
The first problem I've faced just before even linuxCNC code download is that it needs a real time kernel extension - RTAI.
Can some body route a path for me where to dig to reach any results with it please? I mean - how to set RTAI for any OrangePI linux image and how to build linuxCNC for ARM.

Thank you!

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Post time 2016-12-24 12:17:13 | Show all posts
I installed Linuxcnc from here . It does run fine in sim mode.
I have built rt kernel for OrangePi PC Plus running  Debian Jessie from here using information from hereI needed to:
Copy the original kernel config from from /boot on the OPI and put it in ~/userpatches as linux-sun8i-default.config on the build platform
On the build platform rename ~/lib/patch/kernel/sun8i-default/30-real-time143-full-plus-rt-fixes.patch.disabled to ~/lib/patch/kernel/sun8i-default/30-real-time143-full-plus-rt-fixes.patch then run ./compile.sh
After installing the kernel in the OPI and rebooting I ran latency-test and was very disappointed, latency was terrible.





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Post time 2016-12-28 23:59:19 | Show all posts
Well, from what I've experienced RT kernel for OrangePi is not a possible thing, at least not now.
When you simple apply the RT patch, if you do not change nothing when build scripit prompts you, it will produce a kernel with Server preemptive model (No forced Preemption) and this one really do not have a good latency. You need a Fully Preemptive Kernel mode and I recommend to not use desktop distributions for that. But when you try to run it as Full RT it will crash. Well, at least until now, they made no fix for that. Look here https://forum.armbian.com/index. ... th-orangepi-plus-2/
I made a topic in Armbian forum and nothing was made to correct it. So, I think you better get one Atmega microcontroller and burn it with GRBL that you get it nice and working.
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