Best bet for a low cost HW assisted Linuxcnc engine....

My goal:  a X/Y Linuxcnc based system with slow movement speeds (open loop steppers).  The constraints:
* Not old PC desk top based or some kind of windows parallel I/O
* It consists of a cpu running Linuxcnc with a dedicated processor doing the step/pulse interface to stepper drivers
* I think this is pointed at a Remora implementaion however I need something that is relatively stable and functional and *up to date* in terms of the HW.
* Is there  *up to date* documentation on how to install and use it.  I tried in the past to go with Remora and a 3d printer card only to find that the Remora documentation was seriously out of date and I wound up with a dead end.
* I have asked on the Remora part of the forum if the RP2040 based system (which sounds great!) is ready for prime time and I have had no responses since posting it a couple of weeks ago.  Is the impression I am left with which is that it is not ready and the enthusiam for it has died out?  
* I understand the fun of developing and tweaking a solution but for someone who wants to use the system and is somewhat conversant in this subject, figuring out what to commit to is very difficult.  Is there a *real* guide for potential users?  Are people figuring out how to get something to work and not reporting back?  Or are people giving up and just buying the expensive solutions?  Am I completing missing something and my concerns are unfounded?

 

Mars wrote:

Not old PC desktop based
Low cost hardware
Are you thinking something like an SBC (single board computer)?

windows parallel I/O
can you explain, do you refer to gui in general, or Microsoft Windows (LinuxCNC has no current association with Microsoft).

Sounds like an interesting project, just trying to understand what you ask for.

Thanks for your response. I realize that an old PC with parallel port works. Counting on an old PC going forward is not something that appeals to me. I also understand that the Mesa card is solid but the price is less than desirable. Noting that I am not an expert, it seems that the Remora with RP2040 over ethernet should be up to the job and be far cheaper than the Mesa cards. Unfortunately,, I don't have the skills to write the SW so the question remains: Is/or will be Remora with RP2040 ready for prime time? Note: currently I have the Raspberry Pi 5 running Linuxcnc using its GPIO port (buffered with some simple buffer HW but not aux processor) and it will probably meet my needs. That said, a solution based on a cheap aux processor would be a big benefit.

I would have thought that with "Raspberry PI with GPIO" you would have already had your cheap low-cost HW assisted engine.  If you must use a PC and don't want to find one with a parallel port, low-end Mesa cards are my suggestion (like the 7i92TH or 7i96S).  I think with Remora you'd "get what you paid for" and eventually a low-end Mesa card would be a better bargain, and much more turn-key and supported.
 

@Tommy: What do you mean with "China is running a misinformation campaign?", do you refer to some spam we see occasionally here?

@mars: Does, "I also understand that the Mesa card is solid but the price is less than desirable.", mean you wish it was more expensive so that more people would become motivated to follow up with other options?

Mars wrote:

* I have asked on the Remora part of the forum if the RP2040 based system (which sounds great!) is ready for prime time and I have had no responses since posting it a couple of weeks ago.  Is the impression I am left with which is that it is not ready and the enthusiam for it has died out?  
 

I saw your post on the in the Remora forum a week ago. I think that the port to RP2040 is not as developed as other port; one reason is probably that there are only few 3D printer control boards based on this mcu. As Scotta wrote in the post:

scotta post=344968 userid=24854

"This Remora port was a hotel room project when I was travelling for work."

I played a bit with it, mainly because I had some rp2040 around, but never used it to move physical axis. That's the next thing; if you want to interact with real world, a Pico might not be enough. You'll need some buffer and optocouplers. And this is something you get out of the box with the Mesa card. I guess you could also try the PicoCNC board designed for grblHAL and put Remora on it, but it's not that cheap anymore either.

For the RP2040 there's also a component called stepper-ninja that might interest you. But again, you'll not find the maturity of Mesa cards there. Really depends what you plan to do with it.

And if you go with a RPi, yo can also design a HAT for it with some SPI drivers; I designed one with TMC5160 drivers on the top and wrote a LinuxCNC component to send target velocity over SPI; I probably wouldn't use this as is on a CNC mill, but I have a Galvo Laser engraver that is mounted on a 3 axis system, which are connected to that HAT. It's been a year now and never had issue with it, but I only use it more or less an hour per week.

Thanks to everyone for their comments. The overall take away from this is that you want a solution with minimal hassle, go with Mesa and pay accordingly.

Let me ask a related, more targetted question: what is the most solid Remora implementation both in terms of solid operation once configured *and* using HW that is solid and has a reasonable support expectancy. Novusun (sounds iffy), esp32 based? RP2040 (sounds experimental), some kind of 3D printer driver board? Other?