USB-MIDI documentation?

[davidhtims]

I have a Xiao RP2040 working in that the device can be recognized as a MIDI device but I'm lost as to how to send data.
Is there any documentation for USB-MIDI?
I have asked this question in TinyGoMIDI, a Google Group I've started, and the code I have at the moment is there:
https://groups.google.com/g/tinygomidi/c/s8P8fqm3BaE

package main

import (
   "machine"
   "machine/usb"
)

func init() {
   machine.EnableMIDI(midiTx, midiRx, midiSetup)
}

func main() {
}

func midiRx(bs []byte) {
}

func midiTx() {
}

func midiSetup(sup usb.Setup) bool {
   return true
}

[sago35]

To receive and process MIDI signals from a PC or other source, the following code can be used as a reference.

tinygo/src/examples/usb-midi/main.go

Lines 21 to 25 in b5ad81c

	m.SetHandler(func(b []byte) {
	led.Set(!led.Get())
	fmt.Printf("% X\r\n", b)
	m.Write(b)
	})

[sago35]

I think there is no documentation on USB-MIDI at this time.
But would be great to have.

[davidhtims]

Thanks, a question please:

Why or when do I need to use the init function as mentioned in the RP2040 docs:

func init() {
   machine.EnableMIDI(midiTx, midiRx, midiSetup)
}

I'm using tinygo version 0.26.0 darwin/amd64 (using go version go1.19.2 and LLVM version 14.0.0)

Also, in the example tinygo/src/examples/usb-midi/main.go I get an undeclared error on machine.BUTTON.

[sago35]

You do not need to call machine.EnableMIDI() .
EnableMIDI is called internally.

tinygo/src/machine/usb/midi/midi.go

Lines 21 to 25 in b5ad81c

	func init() {
	if Midi == nil {
	Midi = newMidi()
	}
	}

tinygo/src/machine/usb/midi/midi.go

Lines 21 to 25 in b5ad81c

	func init() {
	if Midi == nil {
	Midi = newMidi()
	}
	}

So the first thing you should do is examples/usb-midi.

I get an undeclared error on machine.BUTTON.

If machine.BUTTON is not defined, replace it with machine.GPIO0 , etc.

[davidhtims]

Thanks for the help, I can now send MIDI notes to the pc from Seeed Studio's Xiao RP2040.

[deadprogram]

I just added PR #3889 to make some improvements to the current USB-MIDI support, please have a look.