Up squared board FPGA?

andypugh wrote:

blazini36 wrote: The main reason I like the UP2 is that it has dual NICs if I do stick with a Mesa eth card. I'm not sure how the microprocessor for the Arduino compatible GPIO interfaces the rest of the board, It's my understanding that an actual Arduino can't run in real-time. Is that possible with a board like this and it's GPIO?

The issue is often the interface between the x86 and other chips/peripherals. The Udoo interfaces with the on-board arduino with a USB to Serial link ( sad face ). Ditto the Pi to Ethernet interface. USB (at the moment, and as far as I know) is always likely to fail to meet real-time constraints. So it is important to work out if the UP board has ethernet on the USB bus or PCI (or other usable) bus.

Eww, yeah if it’s running gpio on usb I wouldn’t bother touching it for linuxcnc.

The up2 runs both of the Realtek NICs on separate PCIE ports. Not sure about the FPGA but I think it’s a low latency bus. Even if I can’t do anything with the fpga it’s still gonna work a bit better because of the dual NICs for a Mesa eth card, and it is better hardware reguardless

I think there was a thread recently about the Up board and it was confirmed as working with LCNC but I don't know if they were using the GPIOs. I thought they were fairly expensive so a cheaper PC almost paid for a Mesa 7i76e...

blazini36 wrote:

andypugh wrote: The Udoo interfaces with the on-board arduino with a USB to Serial link

Eww, yeah if it’s running gpio on usb I wouldn’t bother touching it for linuxcnc

It's not necessarily a show-stopper, as it should be possible to set up a realtime UART link to the on-board Arduino and control it somewhat like a Pico or Mesa card (or the Beaglebone PRU). But I had other projects to pursue...

rodw wrote: I think there was a thread recently about the Up board and it was confirmed as working with LCNC but I don't know if they were using the GPIOs. I thought they were fairly expensive so a cheaper PC almost paid for a Mesa 7i76e...

I know it'll run, I came across Machine Koder's blog here with Machinekit
machinekoder.com/compiling-an-rt-kernel-for-the-up-suared/

He says the GPIOs have high latency likely because of the way they're implemented. I'm just trying to judge the usefullness of the FPGA assuming I can get in there to flash it.

The Up2 with a quad core Pentium and 4gb of DDR4 is $240, 7i76e is $200 so I'm not sure what kind of PC you would get for $40, It's a good deal for a < 4"x4" board if you're trying to stay as small as possible for an embedded design. If that FPGA is of any use it's a really good deal if you don't have to buy any motion control hardware at all

But I have to factor in the freight to get to Australia. I only paid AUD $100 for my Gigabyte Brix which is about USD $70 so they are not far apart and what Machine Koder now reccommends on that blog post.

Really seems a bit odd that they didn't think about Real Time when adding the FPGA. LinuxCNC is not the only application that requires it. I also thought their resources and support on their forum was pretty poor.

There aren't any Brix PCs or NUC clones that retail for $70, the cheapest barebones Brix retails for twice that. Sure you can buy a refurb or score a deal on an old model but that's not really what I'm trying to do. I can easily build a MITX system for the cost of a NUC clone, that's what I've been doing anyway. There's actually several other reasons I was looking at the UP2 board, and it's relatively cheap for those reasons.

Machinekoder's response about the Brix was on my comment. Even if the FPGA doesn't work it's still not a deal breaker for me. I am a little disappointed that he says it has poor RT performance in general though I am temped to pick one up anyway and see if I can build a kernel for it or a bios helps.

The machine this thing is going into already has a plenty competent PC. I just like to experiment with hardware to see if I can get the overall parts count down and make everything smaller.

PCW wrote: Yeah their terminology is all different. So the 10M02 has 2000 4-LUTs
This is pretty small (about 1/2 the size of our oldest Spartan2 based cards)
but could fit a couple stepgens and encoder counters etc depending
on the complexity of the host interface

I wouldn't actually need alot of I/O to make that FPGA useful. At the moment it seems that the FPGA is locked up, hopefully they'll release the tools to rewrite it.

Is it realistic to think I could get at least 2 stepgens, a differential encoder counter and maybe 10 I/O out of it?

Yes, that FPGA should hold say 4-5 stepgens and equal number of encoders if the host interface is simple.

You would need a daughtercard for encoder interface (RS-422 differential receivers) and perhaps 3.3V --> 5V translation for the step/dir outputs

Maybe rockpro64+mesa 7i90hd(spi) or 6i24(pciE)
can be a good combination for a tiny size system.
I have ordered this and i will tell you more next days when i get it.

4 stepgens, a PWM gen, a 2 channel encoder, and about 10 GPIO is the max I'd ever need for the thing I'm thinking about sticking this board in.

Looking into the differential receivers you mentioned, it looks like they are basically converting the differential input to a single ended output, so the FPGA side would only be programmed as a single ended encoder to use either? Say if the interface board were jumpered like Mesa cards are, I suppose it would just bypass the differential receiver channel.

I've had fair warning that the board sucks for latency and the FPGA is locked, but solving those 2 issues this board would be great for embedded machines. I just noticed they offer a UPS board that also allows it to accept a 24v power input. I currently Use a DC-DC ATX power supply for my MITX board and it gets hot at full throttle. Kills 2 birds with one stone there. Gonna pick one up to experiment with, it's not like I'm throwing it in my mill and holding up some parts I have to make.