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midi2cpp | Device MIDI 2.0

Teensy 4.1

USB MIDI 2.0 device on the Teensy 4.1 (Cortex-M7 @ 600 MHz, 1 MB SRAM). First Arduino IDE / arduino-cli recipe in midi2cpp. Backend (63 LOC, src/teensy41_midi2.{h,cpp}) bridges the Teensy cores fork USB MIDI 2.0 primitives (usbMIDI2.read/write/altSetting) into midi2::Device / midi2::CI.

teensy41-midi2 banner

override Cores fork + USB names override. Built against the Teensy cores fork sauloverissimo/cores branch feature/usb-midi2-descriptors (USB MIDI 2.0 descriptor + raw I/O primitives, +613 LOC over PaulStoffregen master, not yet submitted upstream). Overlay teensy4/usb.c, teensy4/usb_desc.{c,h}, teensy4/usb_midi2.{c,h} onto your Teensyduino install at ~/.arduino15/packages/teensy/hardware/avr/<version>/cores/teensy4/. Manufacturer + Product strings come from src/usb_names_override.c via the cores' weak-alias hook (usb_names.h).

USB identity

Field Value
VID:PID 16C0:0485 (PJRC USB_TYPE = MIDI2 slot under the V-USB shared VID, kept intact)
Manufacturer github.com/sauloverissimo (via src/usb_names_override.c weak-alias hook)
Product Teensy41 (via src/usb_names_override.c weak-alias hook)
iSerial per-board chip serial
Endpoint Name Teensy41
Product Instance ID Teensy41-showcase-0001
FB 0 Main (Bidirectional, Group 0 in API / Group 1-1 in ALSA, both protocols). Name visible in Windows MIDI Services Console; Linux ALSA shows Group 1-1 since the cores fork GTB descriptor currently emits iBlockItem = 0 (no Block Name string yet).
MIDI-CI Manufacturer ID {0x7D, 0x00, 0x00} (MMA educational prefix)

Forking into a real product requires replacing both VID and PID per USB-IF rules (pid.codes, V-USB sub-allocation, or USB-IF VID).

Build

Requires Arduino IDE 2.x with Teensyduino 1.60+, the cores fork overlaid (see note above), and the midi2cpp + midi2 Arduino libraries on your sketchbook (depends=midi2 (>=0.4.0) pulls midi2 automatically).

arduino-cli compile -b teensy:avr:teensy41:usb=midi2 .
arduino-cli upload  -b teensy:avr:teensy41:usb=midi2 -p <port> .

In the Arduino IDE: Tools > USB Type > MIDI2 before pressing Upload.

Hardware

teensy41-midi2 board

Pin Function
USB device port (micro-USB) enumerates as USB MIDI 2.0 device on host
LED 13 (built-in) not wired

Teensy 4.1 pinout: https://www.pjrc.com/store/teensy41.html.

Validation

aconnect -l                    # client X: 'Teensy41' [type=kernel]
amidi -p hw:X,1,0 -d           # downscaled MIDI 1.0 view
ls /dev/snd/umpC*D0            # raw UMP stream

Windows: Microsoft MIDI Services Console midi endpoint properties shows native data format Universal MIDI Packet (MIDI 1.0 or MIDI 2.0 protocol) and the registered Profile / Properties.

Hardware validated 2026-05-25 on Linux ALSA (rawmidi UMP capture, MT 0x4 / 0xD / 0x0 confirmed) and Windows MIDI Services Console (RC4, Production Preview) showing the showcase loop decoded natively as MIDI 2.0.

Spec coverage

Tier A (Cortex-M7 @ 600 MHz, 1 MB SRAM, full UMP surface in budget).

UMP MT Spec Notes
0x0 JR Timestamp M2-104-UM §3.5.2 heartbeat 500 ms via enableJRHeartbeat
0x4 MIDI 2.0 CV M2-104-UM §4.2 NoteOn/Off (16-bit vel), CC (32-bit), PitchBend (32-bit), ChannelPressure (32-bit), Program, Per-Note PitchBend, Reg Per-Note Controller
0xD Flex Data M2-104-UM §6 Set Tempo (120 BPM), Set Time Signature (4/4)
0xF UMP Stream M2-104-UM §7 Endpoint Info, Device Identity, Endpoint Name, Product Instance ID, FB Info, FB Name

MIDI-CI: Discovery + Endpoint Info, one Profile (addProfile), two Property Exchange properties (DeviceInfo static, ChannelList static + subscribable). Process Inquiry code path present, no setMidiReport call.

Showcase

teensy41-midi2 stack

96-line sketch teensy41-midi2.ino runs a 5-second loop:

  1. sendNoteOn 16-bit velocity 0xC000, 200 ms sustain, then sendNoteOff
  2. sendCC 32-bit on CC 1 (Modulation) and CC 74 (Brightness)
  3. sendPitchBend 32-bit, sendChannelPressure 32-bit, sendProgram
  4. sendPerNotePitchBend and sendRegPerNoteController (Volume)
  5. sendTempo 120 BPM and sendTimeSignature 4/4 via Flex Data

demo_note walks 60..72 across cycles so each NoteOn is distinguishable on a logic analyzer.

License

MIT, inherits parent midi2cpp LICENSE.