LinuxCNC on Raspberry Pi 5

Micro SDCard.

I ran

/opt/vc/bin/vcgencmd measure_temp

So the Pi is sitting at 48.8. Running

sudo chrt 99 ping -i .001 -q 10.10.10.10 -c 50000

50000 packets transmitted, 50000 received, 0% packet loss, time 50045ms
rtt min/avg/max/mdev = 0.102/0.112/0.197/0.006 ms

/opt/vc/bin/vcgencmd measure_temp
temp=50.5'C

So the wee fan and large heatsink appear to be holding the temperature down with a 50 s length increased load.

To try encouraging packet loss, I have plugged in a brushed electric drill into the same plugbox and revved it, and then plugged in a desktop PC with SMPSU. Still 0% packet loss over 10x sends of 5000 packets. Capacitors are not fitted.

Ok, maybe this helps...

Originally I was using 10.10.10.1 as the IP on the Pi 5.

sudo nmcli con mod "Wired connection 1" ipv4.addresses 10.10.10.1/24

ip addr /* returned 10.10.10.1/24 */

For the past day however I have been using 10.10.10.11 because I read somewhere never to use the dot-1.

So I changed back to dot-1 and was able to get intermittant packet loss -- usually 0%, sometimes 1 packet if I used Ctrl+C (see previous posts). In one instance I was able to lose 7 packets.

Further, I was able to lock up the ethernet again.

What happens is I run this command

sudo chrt 99 ping -i .001 -q 10.10.10.10 -c 50000

and I note that the green LEDs on the ethernet are no longer flashing at some point. So I Ctrl+C and there are lots of lost packets (23% or something like that).

But running a ping 10.10.10.10 also now fails, but if I run this again

sudo nmcli con mod "Wired connection 1" ipv4.addresses 10.10.10.11/24

then the ping starts working again and we are all good to go again.

So........ is my sin that I used 10.10.10.1 and it is conflicting with the default gateway that I have not set anywhere but is perhaps defaulting to that IP address?

Mmmmmm.

Back to 10.10.10.11 on the Pi 5 and the ethernet packet losses are still there.

I have moved the Pi PSU to my iPad PSU which can supply 5V @ 3A. I am assuming that with all Apple's wealth, they have built a decent USB-C SMPSU.

sudo chrt 99 ping -i .001 -q 10.10.10.10 -c 5000

5000 packets transmitted, 4995 received, 0.1% packet loss, time 5049ms

rtt min/avg/max/mdev = 0.101/0.110/0.262/0.004 ms.

Is it the RPi OS?

After about 10 lots of 5000 packets, we lose 4 packets. Note that the time also increased from a series of 5003-5004 ms and jumped up to 5040 ms. So we lost 4 packets at a cost of 4x10 ms...

cnc@linuxcnc:~$ sudo chrt 99 ping -i .001 -q 10.10.10.10 -c 5000
PING 10.10.10.10 (10.10.10.10) 56(84) bytes of data.

--- 10.10.10.10 ping statistics ---
5000 packets transmitted, 5000 received, 0% packet loss, time 5003ms
rtt min/avg/max/mdev = 0.101/0.108/0.127/0.004 ms
cnc@linuxcnc:~$ sudo chrt 99 ping -i .001 -q 10.10.10.10 -c 5000
PING 10.10.10.10 (10.10.10.10) 56(84) bytes of data.

--- 10.10.10.10 ping statistics ---
5000 packets transmitted, 5000 received, 0% packet loss, time 5004ms
rtt min/avg/max/mdev = 0.102/0.110/0.134/0.004 ms
cnc@linuxcnc:~$ sudo chrt 99 ping -i .001 -q 10.10.10.10 -c 5000
PING 10.10.10.10 (10.10.10.10) 56(84) bytes of data.

--- 10.10.10.10 ping statistics ---
5000 packets transmitted, 4996 received, 0.08% packet loss, time 5040ms
rtt min/avg/max/mdev = 0.102/0.109/0.242/0.005 ms

Hi RNZ,
Newbie here and very interested in the RPi5 + Mesa 7I96S combo for a new Plasma CNC build.

You mention a 5V @ 3A power supply. Raspberry Pi recommends 5.1V @ 5A. Mesa recommends 4.75 to 5.25V @ 0.4A.

Could this contribute to the issue? Thanks.

Hi ProcksMFG,

I finally had success with my RPi 5 + 7i96s, thanks to excellent support on this forum. I have documented it on this new thread.

forum.linuxcnc.org/9-installing-linuxcnc...th-mesa-7i96s#293645

Regarding your own potential plasma set up, here are a few of my thoughts (even if you didn’t ask for them, LOL, but it does help me clarify my own thinking)…

My current thinking is that I would definitely build a new set up based around the RPi 5 but with one fullback option.

The reasons I would go with the RPi 5 are (I) the minimal form factor which does not require an external bulky PC, (ii) simplicity due to The inbuilt Wi-Fi, and ethernet ports and potential wireless keyboard / mouse via usb dongle, (iii) rapid bootup time (a few seconds) and overall speed of the Pi 5, (iv) The general of availability and future upgrade paths within the Pi family (even if difficult to purchase in the recent past), (v) ease of swapping out the micro SD card to change operating systems, (vi) Staying mainstream, rather than opting for cheaper fringe systems that are not well supported and may not be around in the future.

There are probably other reasons, but I can’t remember what they are at the moment.

The fallback option that I mentioned might be relevant if for some reason my RPi based system started having issues… In that case, I could replace the Pi simply use an external LinuxCNC PC and change one ethernet cable from the Pi---7i96s to PC---7i96s.

Hi ProcksMFG,

Regarding power supplies, I think you are correct about the amperage specs.

By observing the analog meter on my benchtop PSU, it would appear that the RPi 5 draws about 1-2 A depending upon what it is doing. I suspect the five amp spec is designed to allow for high current loads on the USB ports. Since I am not using those ports for anything other than keyboard/mouse wireless dongle, I chose to run from a compact Meanwell 5V/3A PSU that I bought from Mouser.com.

For my final design, I will add a 4,700 or 10,000 uF/ 6.3 V (or 10V or 16V) electrolytic across the 5 V rail (close to the Pi power input) because I have noticed that plugging in the Mesa card causes the Pi to reboot. The Pi evidently has very little on board power supply capacitance.

Hi RNZ,

Thanks for sharing your thoughts. A backup solution is not a bad idea.

I have pretty much the same reasons to go for the RPi5 route. I'm designing a system from ground up and can't picture to see a old desktop tower beside the machine. The electrical panel will also be the human interface with touchscreen. Minimal form factor is important.

I was skeptical on the early results with the RPi5 but your recent flawless experiments are very promising. By the time my machine is built, I'm now confident that any bugs will be fixed.

Do you have any issues with the display settings. I saw early posts says the resolution was stuck at 640x480.

Thanks!