Using MIDI over USB A (Gem Multi, Pd)

Rickus

I just received a Gem Multi and have made good progress getting started but I'm currently stuck trying to get MIDI data from devices connected to the USB A port. I have a small PD test program which uses "notein". It works fine if I send MIDI from the host computer but does not appear to see MIDI from a device attached to the USB A port (have tried a Melbourne Instruments Roto-Control and an Oxi One). It looks like the USB devices are recognised - I can see them in /proc/asound/cards.

Is there some obvious magic I don't know? How can I troubleshoot this? I had a look through some forum messages that mentioned MIDI but didn't find anything useful and I can't find much documentation specific to the Gem.

Some of the commands that might be helpful seem to be missing, e.g. "amidi". Do I need to figure out how to get the Bela connected to the Internet so I can install additional packages?

Thanks, Rick.

giuliomoro

ups my oversight for not including it by default on the image.

Download these three files and drag them on the IDE all at once, then follow the instructions to install.

https://deb.debian.org/debian/pool/main/a/alsa-lib/libatopology2_1.2.8-1%2bb1_arm64.deb
https://deb.debian.org/debian/pool/main/libs/libsamplerate/libsamplerate0_0.2.2-3_arm64.deb
https://deb.debian.org/debian/pool/main/a/alsa-utils/alsa-utils_1.2.8-1_arm64.deb

Then you should have amidi working and amidi -l should tell you the names of your midi devices.

Rickus

Thanks, install done and problem resolved!

giuliomoro

Was the install enough to solve the problem or was it that it allowed you to identify the name of the device?

Rickus

I was able to use "amidi -l" to figure out the device names and see that PD was only setting up a MIDI connection to the host computer. I then added a connection to the Roto-Control on the USB A port by sending a message ("hw 0 0 0" in this case) to "bela_setMidi".

giuliomoro

Do you mean that the connection to the host changed name from hw:0,0,0 to something else when you booted the board with a USB MIDI device connected to it ?

tobias_s

So since I had the same problem i thought i might reply how it went for me.
(Sidenote: dragging into the ide did not work on firefox on ubuntu for me - had to install chromium there it worked.)

when the booting with the usb device connected it detected it as hw:0,0,0. on the old bela it defaulted to hw:1,0,0 and the example C++/Communication/MIDI also still expects hw:1,0,0

Thanks a lot for the quick reply on my other message and sorry for not finding this post!

giuliomoro

tobias_s when the booting with the usb device connected it detected it as hw:0,0,0. on the old bela it defaulted to hw:1,0,0 and the example C++/Communication/MIDI also still expects hw:1,0,0

uff that's annoying ... I guess I'll have to learn udev at last ...

In the meantime a workaround is to always use both (i.e.: add

[loadbang]
|
[hw  0 0 0(
|
[send bela_setMidi]

to your patches), and if you are taking into account the channel of midi messages, use % 16 for them.

Rickus

giuliomoro

giuliomoro In the meantime a workaround is to always use both

Thanks, that's what I did.

giuliomoro

Turns out udev was not needed, instead I had to disable the first slot for USB midi devices in the snd-usb-audio driver configuration. This has now been fixed and pushed. If you update your board and reboot, it will always keep hw:0,0 for the virtual device to the host and USB devices will start showing up from hw:1,0,0 onwards.