Perhaps we can broaden this effort to SoM in general.
( given the small number of soundplane users, and not all are going to want to spend $800 on a Norns., once the underlying ‘tech’ is working, then writing the Matron bit is easy)
I’ve been ‘playing’ in this area for quite a while, it started in 2015, when I was getting the Eigenharps to work on the rPI, and found a bug in the isosynchronous usb handling in the rpi kernel,
you can see that report here , this is relevant since it affected the soundplane as well.
fortunately, at some point it got fixed 
but… ever since then, Ive found it can at times be a bit ‘fragile’, with slight odd issues.
e.g. randomly, some kernel releases , the Eigenharp Pico needs a usb hub, but next release and it doesn’t, repeat and rinse!
anyway… here is where I am at the moment, having tested the soundplane on a wide variety of boards!
PI based solutions
- a CM3 based solution 4.14.93
works perfectly
- Norns Clone - rPI 3b+ (setup as Norns)- 4.14.62 (note: norns uses 4.14.52)
did not appear to work, no data received BUT caveat!
- Norns Clone - rPI 3b+ , upgrade kernel to latest 4.19.27
this APPEARED not to work, and accidentally, I found that after 30-45 seconds, it starts to work - so initialisation (calibration?) was taking a very long time (its ‘instant’ on other board)
(its possible the the 4.14.62 may have worked, but just taken a long time to initialise - though I thought id waited a while on it too !)
- rPI ‘standard’ stretch, minimal install 4.14.48
same slow initialisation.
Non rPI solutions
- Organelle - 3.x kernel, arch linux
does not work, submit_urb_error -28, I think its simply a bandwidth issue, though oddly it works with eigenharps - but its on a really old 3.x kernel - I need to re-test with a a 4.x kernel
- Beaglebone Black w/ Bela include Bela Salt (Eurorack) - 4.4.113 xenomai
always worked perfectly 
- ASUS Tinkerboard 4.4.32
appears to get NO data, but doesn’t matter how long you leave it, it doesn’t initialise,
again an old kernel, so might work with a 4.6+ kernel
note: as you’ll see in the bug report above, the fixed appeared to come around 4.4.48!
(macOS also works fine with my same code)
Summary
on the rPI platform, there seems to be some kind of minor issue with it taking a long time to initialise… lets, assume the ‘failed’ one is a testing issue, even though it seems unlikely.
the CM3 platform is interesting, its theoretically same setup as other rPI, but doesn’t have the issue… and the CM3 hardware should not matter, it uses the same BCM2835 as the rPI3.
anyway, I guess the Norns will work… perhaps with slow initialisation, and perhaps the kernel may need reviewing - but we will only know once its tested on an actual norns.
on my side, for SOM, I do want to test the Organelle and Tinkerboard on later kernels.
and I guess, I’ll break out usbmon and see if i can find out what’s going on with the initialisation on the rPI boards.
Im pretty excited in this area, as Ive got a couple things ‘coming’ , that are going to be awesome with the Soundplane (and Eigenharps)
enough words… getting rid of the computer, can be really liberating
here is the Soundplane working without computer, supplying CV directly to an AE modular. (I also do the same for Eurorack with Bela Salt , but no video yet 
)
and, very similar tech (usb iso) , and same goal, ditching the computer!
… here is the Eigenharp pico with an Organelle,
