Linuxcnc on Raspberry

rpi4 4g elovalvo's 64bit img
isolcpus=1,2,3 idle=poll
screenblanking disabled
latencyhistogram --base 80000 servo=1000000
4 glxgears
after 14hrs
30.2uSmax latency
w00t!
thx again
tomp

tjtr33 wrote: hello, now running kernel 5.10. on rpi4 4G
usb wifi ok without choking memory

pi@raspberrypi:~ $ uname -a
Linux raspberrypi 5.10.25-rt35-v7l+ #1 SMP PREEMPT_RT Wed Mar 24 19:51:39 PDT 2021 armv7l GNU/Linux

pi@raspberrypi:~ $ free
total used free shared buff/cache available
Mem: 3919140 132908 3538204 37312 248028 3619740
Swap: 102396 0 102396

This was using the newest ( 15apr2021) from kdoren as Andy Pugh mentioned
using kernel .debs ( not building)

goto
github.com/kdoren/linux
and on right side of page, look for 'Releases'
click that
and scroll down to
"To install from deb packages, as root:"

1st get a root pwd ( google it )
2nd follow his notes
3rd reboot

the latency is not impressive for stepper people,
80uS base immediately got an UnxpectedRealtimeDelay

tomp

thanks that was helpful

Is there still a 30k max step rate though sence the rpi4 does not have a dedicated i/o chip like a beegle

The Mesa 7190HD is 59USD and works over SPI has anyone given this a shot yet?

Cncninja wrote: The Mesa 7190HD is 59USD and works over SPI has anyone given this a shot yet?

I think that Pi + 7i90 is the config that Gene (on the mailing list) is running his Sheldon lathe with.

Hi Cncninja,
I am assuming you are talking about software step generation with RPi4.

Given that, do you mean 30000 steps per second? or per minute?

30000 per second requires less than 33uS period for thread AND doublestep.

At my tested 80uS thread I can do a bit less than 12500 per second.
( 1 sec / .000080 sec = 12500 thread cycles per second , at most )

tomp