Remora for RP2040

I don't want to seem intrusive. But does anyone have an idea and could help?

Limo wrote:

I don't want to seem intrusive. But does anyone have an idea and could help?

 

Hi, maybe this thread could help
Lathe Spindle control with step/dir - LinuxCNC

limo, I saw you in the discord the otherday I think, you arent using the rp2040 right?

Is remora capable of doing it? Most likely, so long as you stay within the parameters of the remora board you are using, by which I mean, if your stepgen steprate is too high, remora might not be able to accommodate. Otherwise it sounds like a standard affair, as just configuring a stepgen.

Do we know how to configure a spindle with step/dir with remora? I dont personally. The bulk of it will be linuxcnc, and we can help you with connecting to remora

Yes, that was probably me over on Discord.
In terms of hardware I wanted to use the 2040 because it is rather cheap and I can get it pretty easy.
I have managed to make a spindle work with stepgen in the past. I am just a little unsure how to connect it to remora. My thought is that in remora I just add a velocity joint in addition to my other joints/linear axis. And then connect the spindle.0.speed-out-rps to the remora.joint.0.vel-cmd. But I think I got a little confused with what an actual joint is in linux-cnc.
That thread what scotta linked was actually from me.
If I notice that remora with rp2040 can't obtain the step rates it is cheap "fail", and then I will investigate other options.
Thank you.

We would probably need to do some math to verify that it can provide the step speeds you need for all axis. I saw you mentioned something about an encoder, but rp2040 cannot do encoders if thats also what you need.

Encoder support is also something I am looking to have. Then the rp2040 is then probably not the best option any more. How can I estimate the performance in terms of drive frequency for the axis?

Limo wrote:

Encoder support is also something I am looking to have. Then the rp2040 is then probably not the best option any more. How can I estimate the performance in terms of drive frequency for the axis?

I think this is how to do the math for the axis timing, im fairly sure its the same idea
linuxcnc.org/docs/devel/html/motion/twea...ose_your_base_period

If encoder support is what you need, the rp2040 does not support encoders at this time, and im not sure if it will or what its limits will be. the RT1052 will probably be your best bet if you want something ethernet

I have looked through the remora documentation and there are software encoders mentioned with a frequency up to 30kHz. If I get close to that number with a rp2040 I am fine with that. That would result in theoretical encoder resolution to roughly 360ppr with 5k rpm and 30kHz max input frequency. It is just the question if the pi2040 is up to the task of handling these things

As Cakeslob mention, the RP2040 fork does not currently have encoder (software or hardware) support. It wouldn't take much to port over the software encoder module to the RP2040 though. Limited to base thread frequency.

github.com/scottalford75/Remora/tree/mai...-OS5/modules/encoder

If someone was keen they could also potentially look at the PIOs to increase the capable frequency.

github.com/p-o-l-e/quadrature-decoder

How much effort in programming skills are needed, to implement the hardware encoder support with the PIO? And where is the best place to start. To be honest I am not very familiar with linuxcnc let alone remora. If it is within my capabilities I would really want to get a go at it. I would really appreciate if someone can point me in the right direction where to start looking.