Linuxcnc on Raspberry

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15 Apr 2021 13:14 #206004 by tjtr33
Replied by tjtr33 on topic Linuxcnc on Raspberry
I have built a pcb to interface the RPi to a Ramps1.4 pcb.
It has 3 TXS0108e chips for 3.3 <-> 5V level shifting
I am in testin with it now.

There are lots of news on the Pi cnc frontier,
and I only test a few.

lots to do!
tomp
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15 Apr 2021 13:48 #206007 by AgentWD40
Replied by AgentWD40 on topic Linuxcnc on Raspberry
Is this pcb your own design? Will you make the schematics/design files open to the public?

Does this project use linuxcnc or is it still using marlin/grbl on the ramps?

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16 Apr 2021 06:33 - 16 Apr 2021 07:18 #206084 by tjtr33
Replied by tjtr33 on topic Linuxcnc on Raspberry
1)yes , my design. and yes its free & open source ( its just a wiring harness turned into a pcb with level shifters )
2)it's for linuxCNC , the ramps1.4 itself has no brains ( it is usually plugged into a mega but not here )
also the design will work with PYcnc ( the dma stepper ).
I am waiting the 2nd revision pcbs ( more ground fill and moved 1 connector a tad )
Then will make available
here is the beta in kicad format

You should be able to an Orange pi by rotating the assembly of the shim and ramps shield by 180 degree,
It will just plug in

tomp
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Last edit: 16 Apr 2021 07:18 by tjtr33. Reason: clarity ( clarabell-ity :-)

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16 Apr 2021 07:04 #206088 by tjtr33
Replied by tjtr33 on topic Linuxcnc on Raspberry
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
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17 Apr 2021 19:36 #206210 by cakeslob
Replied by cakeslob on topic Linuxcnc on Raspberry
if you are using hardware stepping and having latency issues, perhaps try the 64bit image elvalo posted
forum.linuxcnc.org/9-installing-linuxcnc...i-4-8gb-2gb?start=50
forum.linuxcnc.org/9-installing-linuxcnc...xcnc?start=40#204950

67-80 has been pretty much the average for me accross the 32bit images ive used (without playing with cmdline stuff), but on the 64bit images, despite being power hungry, im getting 20-50 with glxgears
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19 Apr 2021 13:57 #206383 by tjtr33
Replied by tjtr33 on topic Linuxcnc on Raspberry
re elovalvo;s 64bit image for rpi 4

my interests are for native software stepping
so thats why i run these tests this way....

It looks good so far with latency-histogram --nase 80000 --servo 1000000
I booted with isolcpus-1,2,3 idle-poll
screensaver killed
4glxgears at 60fps each
at 5123 seconds (85.4minutes)
I will let it cook overnight

I will try base thread at 50us if good tomoorw morning.

this is on a
pi4 4G with arctic cooler and 3amp wall wart, logitech usb kbd&mouse
and a 30 inch hdmi display ( i dunno rez )

30.2uS max latency on base
19.5uS max on servo

thx elovalvo again
tomp

btw most problems that i encounter with img's on pi
are from the sd cards
not dd/rp-imager/balena
not bad downloads
usually the src != dest ( bad sd's )
it is important to use a write method that verifies

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20 Apr 2021 02:44 #206495 by tjtr33
Replied by tjtr33 on topic 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
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26 Apr 2021 11:49 #207103 by tinah
Replied by tinah on topic Linuxcnc on Raspberry

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

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