2914174d27
Follow-up on newly introduced USB MIDI2 support. Prefix with usbd_, use midi2 consistently. Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>
85 lines
2.5 KiB
ReStructuredText
85 lines
2.5 KiB
ReStructuredText
.. zephyr:code-sample:: usb-midi2-device
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:name: USB MIDI2 device
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:relevant-api: usbd_api usbd_midi2 input_events
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Implements a simple USB MIDI loopback and keyboard device.
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Overview
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********
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This sample demonstrates how to implement a USB MIDI device. It can run on
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any board with a USB device controller. This sample sends all MIDI1 messages
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sent to the device back to the host. In addition, presses and release on
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input keys (such as the board user buttons) are sent as MIDI1 note on and
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note off events.
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The application exposes a single USB-MIDI interface with a single bidirectional
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group terminal. This allows exchanging data with the host on a "virtual wire"
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that carries MIDI1 messages, pretty much like a standard USB-MIDI in/out adapter
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would provide. The loopback acts as if a real MIDI cable was connected between
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the output and the input, and the input keys act as a MIDI keyboard.
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Building and Running
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********************
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The code can be found in :zephyr_file:`samples/subsys/usb/midi`.
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To build and flash the application:
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.. zephyr-app-commands::
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:zephyr-app: samples/subsys/usb/midi
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:board: nucleo_f429zi
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:goals: build flash
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:compact:
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Using the MIDI interface
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************************
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Once this sample is flashed, connect the device USB port to a host computer
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with MIDI support. For example, on Linux, you can use alsa to access the device:
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.. code-block:: console
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$ amidi -l
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Dir Device Name
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IO hw:2,1,0 Group 1 (USBD MIDI Sample)
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On Mac OS you can use the system tool "Audio MIDI Setup" to view the device,
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see https://support.apple.com/guide/audio-midi-setup/set-up-midi-devices-ams875bae1e0/mac
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The "USBD MIDI Sample" interface should also appear in any program with MIDI
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support; like your favorite Digital Audio Workstation or synthetizer. If you
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don't have any such program at hand, there are some webmidi programs online,
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for example: https://muted.io/piano/.
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Testing loopback
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****************
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Open a first shell, and start dumping MIDI events:
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.. code-block:: console
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$ amidi -p hw:2,1,0 -d
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Then, in a second shell, send some MIDI events (for example note-on/note-off):
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.. code-block:: console
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$ amidi -p hw:2,1,0 -S "90427f 804200"
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These events should then appear in the first shell (dump)
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On devboards with a user button, press it and observe that there are some note
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on/note off events delivered to the first shell (dump)
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.. code-block:: console
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$ amidi -p hw:2,1,0 -d
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90 40 7F
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80 40 7F
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90 40 7F
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80 40 7F
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[...]
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