It it possible to name separate USB MIDI interfaces? #16435
Replies: 2 comments 6 replies
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Not from the USB side, I don't think. There's no string field in any of the MIDI descriptors, just the device product string. You might be able to change the names in the host computer OS, or in Windows maybe even via a custom .inf driver file, but I'm guessing that won't solve the problem for you.
This is probably the way, although I think these also won't provide you with different names just different numbered "Jack IDs". As per the comment here, the driver has all of the structure to add multiple "jacks" in one descriptor but I didn't have a lot of luck getting something useful out of it. |
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Oh actually I am wrong, there is an interface string descriptor index (iInteface) that's currently not passed through by the driver in this call: You could try patching the desc_cfg() function in midi.py to something like: def desc_cfg(self, desc, itf_num, ep_num, strs):
# Start by registering a USB Audio Control interface, that is required to point to the
# actual MIDI interface
desc.interface(itf_num, 0, _INTERFACE_CLASS_AUDIO, _INTERFACE_SUBCLASS_AUDIO_CONTROL, iInterface=len(strs))
strs.append("interface string")If this works then we could add an optional |
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{{editor}}'s edit
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A couple of caveats here that have been confusing to CircuitPython users, where we have a MIDI renaming capability:
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Thanks for the heads up, @dhalbert. If there is a jack name capability in USB MIDI then my first reply is wrong on two counts! Apologies, @HLammers. I'll try and dig into this more when I have some time. |
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See https://docs.circuitpython.org/en/latest/shared-bindings/usb_midi/index.html#usb_midi.set_names. Also, we recently found this gotcha on Windows, that jack names longer than 31 chars break something, even though that's not inherently a USB length restriction that we know of: adafruit#9871 |
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Thanks @projectgus and @dhalbert! I tried patching the But now it creates three MIDI ports, each called ‘Interface 6’, while it should be ‘Interface 4’, ‘Interface 5’ and ‘Interface 6’ (numbers 1 to 3 are taken by the dummy calls to desc_cfg). I do not have time now to do more testing to try to figure out why it refers each time to the last string. I guess the clue to that must be in core.pi. The annoying thing is that I’m using VS Code (on Windows 11), with the MicroPico extension, which doesn’t reconnect to the REPL after |
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@projectgus, do you know if there’s a way to make vREPL work in VSCode (using MicroPico) while running USB enabled code? I finally want to start working on getting this to work again to integrate it into my Cybo-Drummer project. I found some hints here and there that the solution might be to have multiple MIDI Streaming Interfaces, each with its own Interface Descriptor and MS Interface Descriptor blocks, and use the iInterface parameter to point to unique names. |
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@HLammers I haven't tried the VSCode plugin, but unfortunately I'm guessing "no" - the USB serial device will appear to disconnect and reconnect whenever the board soft resets and the host program has to manage this. (We are in the process of getting support for automatic reconnections in mpremote via #17322 - once this lands it might be a convenient example for other programs to emulate, but they'll need to implement support themselves.) |
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It is fairly easy to implement multiple midi interfaces over one USB connection, but how do I give each one a unique name?
To demonstrate what I’m talking about, let‘s modify midi_example.py, by changing lines 45 to 47:
into:
After this change three MIDI connections show up in my DAW (FL Studio 2024): ‘Test’, ‘Test #2’ and ‘Test #3’. I assume they acually are all three called ‘Test’ (i.e. the product string value) and ‘#2’ and ‘#3’ are added by the DAW itself. Is there any way to give each Interface instance a unique name, via product string or otherwise?
Edit
Perhaps multiple virutal cables is a better approach to achieve this, but that hasn’t been implemented in usb.device.midi. Does anyone know how to implement that?
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