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zephyr-usb-midi

This is a USB MIDI 1.0 device class driver for the Zephyr RTOS, which allows sending and receiving MIDI data over USB.

The current implementation, which uses Zephyr's soon-to-be legacy USB stack, is usable but should be considered work in progress and needs more testing before it's ready for real world use. If you run into any issues, please consider reporting them or submitting a PR.

Usage

The USB MIDI device class driver is contained in a Zephyr module. The sample app's CMakeLists.txt file shows one way of adding this module to an app.

The public API is defined in usb_midi.h.

Sample app

The sample app demonstrates how to send and receive MIDI messages and how to efficiently send large sysex messages to the host. It also logs sysex transfer speeds and can echo incoming sysex messages. See Kconfig for sample app config vars.

  • Button 1 - Send a large sysex message
  • LED 1 - On when the device is connected to a host
  • LED 2 - Flashes when MIDI data is received
  • LED 3 - Flashes when MIDI data is sent

The app should work on dev boards with at least one button and three LEDs, for example stm32f4_disco and nrf52840dk_nrf52840.

zephyr_usb_midi_sample.mp4

Configuration options

  • CONFIG_USB_DEVICE_MIDI- Set to y to enable the USB MIDI device class driver.
  • CONFIG_USB_MIDI_NUM_INPUTS - The number of jacks through which MIDI data flows into the device. Between 0 and 16 (inclusive). Defaults to 1.
  • CONFIG_USB_MIDI_NUM_OUTPUTS - The number of jacks through which MIDI data flows out of the device. Between 0 and 16 (inclusive). Defaults to 1.
  • CONFIG_USB_MIDI_USE_CUSTOM_JACK_NAMES - Set to y to use custom input and output jack names defined by the options below.
  • CONFIG_USB_MIDI_INPUT_JACK_n_NAME - the name of input jack n, where n is the cable number of the jack.
  • CONFIG_USB_MIDI_OUTPUT_JACK_n_NAME - the name of output jack n, where n is the cable number of the jack.