raspberry pi 3 model b+ support realtime

*bump* for the previous question. I see the 7c81 is in the store, but not the 7c80.

Can the rpi run the ethernet mesa cards like the 7i76e and 7i96?

Finally and most importantly, thoughts on the new rpi 4 with linuxcnc/mesa?

The Pi3 does not work with Ethernet Mesa cards as the ethernet is on the USB bus.

But: It seems that this is not the case with the Pi4. So there is more chance of that working.

The raspian_stretch_full.gz file here is supposedly a pre-installed LinuxCNC image for the Pi3B+. I haven't tried it myself (I was going to do the same thing, but got beaten to it)

geneslinuxbox.net:6309/gene/Genes-os9-st...ebian-stretch-armhf/

Hi everyone!
I just want to leave my experience here because I've been able to successfully use an Pi3b+ with a Mesa 7i92 + 7i77 + 7i84 boards.
It was implemented on a Pinacho Lathe with servo motors and controls everything (including PLC logic) with a servo_thread of 2.5ms.
It controls 2 axis + Spindle + 2 MPG hand weels + Spindle Gearbox (3 gears) + ATC Turret + control panel with basic buttons and analog signals to control the feed bars on Gmoccapy.
(LinuxCNC v2.7.14)

Regarding the Pi4 stuff, I'm currently building a PREEMPT-RT kernel on mine to start testing it out, so I'll post updates about it in the Pi4 topic.

Rpi4 already working with LCNC:

forum.linuxcnc.org/18-computer/36879-raspberry-pi-4?start=0

Two mesa boards already tested and working over SPI and Ethernet.

spma wrote: Hi everyone!
I just want to leave my experience here because I've been able to successfully use an Pi3b+ with a Mesa 7i92 + 7i77 + 7i84.

Interesting. You wouldn't normally expect that to work as the Pi3 ethernet is on the USB bus and that tends to make accurate timing impossible.

Pi4 has he ethernet on the PCIe bus, and then the servo thread at 1mS works fine with an ethernet board.

andypugh wrote: Interesting. You wouldn't normally expect that to work as the Pi3 ethernet is on the USB bus and that tends to make accurate timing impossible.

True but I tested it thoroughly and the 2.5ms of servo_thread period was more than enough for a 30yo SLOW lathe with a maximum joint precision of 0.05mm... and it outputted that precision while machining

andypugh wrote: Pi4 has he ethernet on the PCIe bus, and then the servo thread at 1mS works fine with an ethernet board.

Yes, the Pi4 would now be a better choice, but we're talking about a project I started almost 2 years ago...
The next project I'll get a chance I'll invest some time testing it with the Pi4.

Simão A.