LinuxCNC + Orange Pi
after 947 seconds
-283 +249 latency
and again with 2000000 ( 2mS servo only )
263 222 at 500seconds
latency doesnt matter (as much) if arisc handles the time critical processes.
I think the latency is interesting but not crucial.
I have a limited perspective due to my needs,
and may easily fail to see needs of others.
So, here's 2 questions of interest:
Is there someplace to put 'isolcpus=1,2,3 idle=poll" ?
Is there any benefit to moving OS from SD to eMMC ?
Already answered here forum.linuxcnc.org/38-general-linuxcnc-q...c-pwm-success#207612
tjtr33 wrote: Is there someplace to put 'isolcpus=1,2,3 idle=poll" ?
MX_Master wrote: Hi, TomP.
`isolcpus ...` can be added to the armbianEnv.txt or directly to the boot.cmd/scr inside setenv bootargs "... here ..."
disk IO speed x 4
tjtr33 wrote: Is there any benefit to moving OS from SD to eMMC ?
So what I used is a Arduino cnc shield V4
Unfortunately it only supports 12 volt.
Since I am using an old laptop power supply which is 19 volt. So 12 volt is not an option. I figured out that the limit is the onboard regulator for the arduino. So I removed it. Capacitors are 47V. But now I need 5v for the Pololu 8825 drivers. Can I take that from the 5 volt pin of the orange pi?
I edited boot.cmd
and then did
sudo mkimage -C none -A arm -T script -d /boot/boot.cmd /boot/boot.scr
now latency-histrogram --nobase --servo 1000000
has values cut in half ( compared to before editing boot.cmd)
after 1/2 hour with 4 glxgears
i have -153 and +138 uS latency
I did not move OS from SD to eMMC yet,
I will let the latency test cook overnight
I ran latency-histogram on the opi+2e armbian buster xfce
--base 80000 --servo 1000000
and got (after more than 13 hours)
base -44.5 +46.8
servo -115.9 +121.7
the editing for isolcpus and idle definitely help
it does slow down the axis gui, but acceptable
( if you "lower your expectations" TM SNL )
Add the ntp 'fix' from samco
Move the os from sd to emmc
Drive these closed loop stepperd LC57H380+LCDA357H
Build and study the app 'tuna' for tuning rt environments
I have similar jitter here. I also tried with isolcpus=2,3 and =3 and GUI performance was snappier and the jitter stayed about the same.
There is noticeable improvement when GPU hardware accel is used with the Rpi4. At some point I'll have to see how much better it behaves on the Opi's with hardware accel.