Allow changing the iJack name for MIDI when we do dynamic USB descriptors

[infovore]

I've been prodding this library as an alternative to some other code I have, and it's super-impressive. One question: what's the most appropriate way to change the auto-generated device name?

In my MIDI Monitor tool, I get this:

and I've had good success with other boards on changing the detected devicename - which I appreciate might be a USB setting rather than a MIDI-specific setting. I'm new to CP, so am imagining this is a settings.py or boot.py issue, but don't quite know where to begin.

[dhalbert]

This is set in CIrcuitPython at compile time:

circuitpython/tools/gen_usb_descriptor.py

Lines 398 to 458 in 11e510a

	if include_audio:
	# Audio!
	# In and out here are relative to CircuitPython
	# USB OUT -> midi_in_jack_emb -> midi_out_jack_ext -> CircuitPython
	midi_in_jack_emb = midi.InJackDescriptor(
	description="MIDI PC -> {}".format(args.interface_name),
	bJackType=midi.JACK_TYPE_EMBEDDED,
	iJack=StringIndex.index("{} usb_midi.ports[0]".format(args.interface_name)),
	)
	midi_out_jack_ext = midi.OutJackDescriptor(
	description="MIDI data out to user code.",
	bJackType=midi.JACK_TYPE_EXTERNAL,
	input_pins=[(midi_in_jack_emb, 1)],
	iJack=0,
	)
	# USB IN <- midi_out_jack_emb <- midi_in_jack_ext <- CircuitPython
	midi_in_jack_ext = midi.InJackDescriptor(
	description="MIDI data in from user code.", bJackType=midi.JACK_TYPE_EXTERNAL, iJack=0
	)
	midi_out_jack_emb = midi.OutJackDescriptor(
	description="MIDI PC <- {}".format(args.interface_name),
	bJackType=midi.JACK_TYPE_EMBEDDED,
	input_pins=[(midi_in_jack_ext, 1)],
	iJack=StringIndex.index("{} usb_midi.ports[1]".format(args.interface_name)),
	)
	audio_midi_interface = standard.InterfaceDescriptor(
	description="Midi goodness",
	bInterfaceClass=audio.AUDIO_CLASS_DEVICE,
	bInterfaceSubClass=audio.AUDIO_SUBCLASS_MIDI_STREAMING,
	bInterfaceProtocol=audio.AUDIO_PROTOCOL_V1,
	iInterface=StringIndex.index("{} MIDI".format(args.interface_name)),
	subdescriptors=[
	midi.Header(
	jacks_and_elements=[
	midi_in_jack_emb,
	midi_in_jack_ext,
	midi_out_jack_emb,
	midi_out_jack_ext,
	]
	),
	standard.EndpointDescriptor(
	description="MIDI data out to {}".format(args.interface_name),
	bEndpointAddress=args.midi_ep_num_out | standard.EndpointDescriptor.DIRECTION_OUT,
	bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
	bInterval=0,
	wMaxPacketSize=512 if args.highspeed else 64,
	),
	midi.DataEndpointDescriptor(baAssocJack=[midi_in_jack_emb]),
	standard.EndpointDescriptor(
	description="MIDI data in from {}".format(args.interface_name),
	bEndpointAddress=args.midi_ep_num_in | standard.EndpointDescriptor.DIRECTION_IN,
	bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
	bInterval=0x0,
	wMaxPacketSize=512 if args.highspeed else 64,
	),
	midi.DataEndpointDescriptor(baAssocJack=[midi_out_jack_emb]),
	],
	)

, so you would need to do a custom build of CircuitPython to change it.

We are going to work on dynamic USB descriptors, so setting this name could be a capability we would add. It would not be in this library. If you are interested in this, I will migrate this issue to the circuitpython repo.

[infovore]

@dhalbert yes, that sounds like a good fit - I can see now it's part of the usbmidi code. It'd be a nice-to-have alongside custom USB descriptors (which I've used a lot on other prototyping boards as part of products).

[dhalbert]

transferred and re-titled

[kevinjwalters]

@infovore How do two boards show up in that tool?

[samkusnetz]

hello. i'm a relatively new user of circuitpython, recently crossing over from my long, long time with arduinos. i would enthusiastically appreciate this feature!

[dhalbert]

Superseded by #4191.