esp32-c6-devkitc-multi-midi2

midi2cpp | Device MIDI 2.0

ESP32-C6-DevKitC-1 (BLE + ESP-NOW)

Wireless MIDI 2.0 device on the ESP32-C6-DevKitC-1, exposing two transports in parallel: BLE-MIDI 1.0 (standard Apple / MIDI Association service UUID) and ESP-NOW (peer-to-peer, broadcast on WiFi channel 1). The C6 has no USB-OTG hardware (only USB-Serial-JTAG), so the canonical USB MIDI 2.0 device interface is unavailable on this chip; this recipe demonstrates the wireless path instead. Built on ESP32_Host_MIDI v6.0.0 + arduino-esp32 v3.x. PlatformIO build.

No fork, no override. This recipe uses no TinyUSB and depends on no pending pull request.

Both wire transports carry MIDI 1.0 byte streams natively (BLE-MIDI 1.0 spec, ESP-NOW small payload). Bytes are uplifted in firmware to UMP MT 0x2 via midi2::ByteStreamConverter so the application sees the same typed midi2::Device dispatch surface used by the USB recipes; outbound UMP from the showcase loop is downgraded to MIDI 1.0 bytes before hitting the wire.

Identity

No USB device interface, no PID consumed. Identity is per transport.

BLE

Field	Value
Role	BLE peripheral (GATT server)
Service UUID	03B80E5A-EDE8-4B33-A751-6CE34EC4C700 (BLE-MIDI 1.0, Apple / MIDI Association)
Characteristic UUID	7772E5DB-3868-4112-A1A9-F2669D106BF3
Advertised name	Esp32C6Multi
MAC	burned-in (read at boot, printed to UART)

ESP-NOW

Field	Value
Role	ESP-NOW broadcaster + receiver, WiFi STA mode (no AP association)
Channel	1 (recipe constant, both peers must match)
Peer addressing	broadcast on FF:FF:FF:FF:FF:FF by default; ESPNowConnection::addPeer switches to unicast
Local MAC	burned-in (printed at boot for pairing)

Build

Requires PlatformIO Core 6.x+, an ESP32-C6-DevKitC-1, USB-C cable to the right-side jack (CH340 USB-to-UART for log + flash).

cd pio
pio run
pio run -t upload -t monitor

The C6 is not in the upstream espressif32 PlatformIO platform; support comes from pioarduino/platform-espressif32 pinned to release 53.03.13 in platformio.ini. Partition table is huge_app.csv (3 MB app slot) because BLE + WiFi + ESP-NOW + arduino-esp32 v3 exceeds the default 1.6 MB layout.

Flash via the left jack (USB-Serial-JTAG, recommended)

The C6 has a built-in USB-Serial-JTAG controller wired to the left jack (303a:1001 Espressif USB JTAG/serial debug unit). esptool talks to it directly over USB DFU, no auto-reset circuit involved.

pio run -t upload --upload-port /dev/ttyACM1
pio device monitor -p /dev/ttyACM0      # monitor on the right jack (CH340)

Flash via the right jack (CH340)

The CH340 path depends on auto-reset via DTR / RTS. On some board revisions strapping jumpers J1 / J2 are not populated and esptool reports Failed to connect: No serial data received. Fall back to the USB-Serial-JTAG path above, or hold BOOT, pulse RST, release BOOT.

pio run -t upload -t monitor

Hardware

Pin / port	Use
USB-C (right jack, CH340)	Host UART log @ 115200 8N1 + esptool flash entry. Default /dev/ttyACM0
USB-C (left jack, USB-Serial-JTAG)	Native USB-Serial-JTAG for flashing + secondary console
2.4 GHz PCB antenna	Shared by WiFi (ESP-NOW) and Bluetooth 5 LE (BLE-MIDI). Coexistence handled by the WiFi / BT controller
GPIO8	On-board RGB LED (WS2812). Not driven
BOOT (GPIO9)	Hold during reset to enter download mode

The C6 is single-core 32-bit RISC-V Wi-Fi 6 + Bluetooth 5 LE + 802.15.4. Only the WiFi 4 / 5 paths in arduino-esp32 v3 are exercised here. 802.15.4 is unused.

Validation

pio device monitor -p /dev/ttyACM0

After flash the boot banner prints, followed by [BLE] advertised name = "Esp32C6Multi" and [ESPNW] begin() = ok, channel = 1, local MAC = XX:XX:XX:XX:XX:XX.

BLE: pair Esp32C6Multi from any BLE-MIDI 1.0 client (iOS / iPadOS Audio MIDI Setup, macOS Audio MIDI Setup with the BLE bridge, Android USB MIDI BLE Bridge, MIDI BLE Connect on Windows, BlueZ 5.65+ on Linux). The C major scale appears as Note On / Off in the host's MIDI monitor.

ESP-NOW: flash a second ESP32 on channel 1 in receive mode (any esp-now responder example or another copy of this firmware). Notes emitted by board A print on the UART of board B.

Sending notes back from either transport prints [NoteOn ] BLE ... or [NoteOn ] ESPNW ... on this board's UART.

Spec coverage

Tier B (MIDI 1.0 wire, UMP MT 0x2 surface). The C6 is RAM-rich (512 KB SRAM) but the wire transports cap at MIDI 1.0 byte payloads.

UMP MT	Direction	Spec	Notes
0x2 MIDI 1.0 Channel Voice	RX + TX	M2-104-UM §6	uplifted from BLE / ESP-NOW byte streams via midi2::ByteStreamConverter, dispatched through Device::onNoteOn / onNoteOff / onCC / onProgram / onPitchBend / onChannelPressure / onPolyPressure
0x4 MIDI 2.0 Channel Voice	TX only	M2-104-UM §7	the setWriteFn fan-out detects MT 0x4 and downgrades to MT 0x2 via Device::downgradeMt4ToMt2 before serialising. RX not exercised, neither wire carries 32-bit values
0x1 System Real-Time / Common	TX	M2-104-UM §4	one byte per System UMP word; not exercised by the showcase

SysEx7 (multi-packet across BLE 20-byte / ESP-NOW 4-byte frames), SysEx8, Flex Data, UMP Stream are dropped. Reassembly across packets requires per-transport state not in v0.1 scope. Promoting this recipe to Tier A would require a UMP-over-BLE custom service or UMP-over-ESP-NOW packing scheme, neither in scope.

MIDI-CI: not applicable (no MIDI-CI traffic on the wire because both transports are MIDI 1.0 byte streams, and SysEx-based MIDI-CI requires the missing reassembly path).

Showcase

Always on:

• BLE advertiser running with name Esp32C6Multi
• ESP-NOW STA mode active on channel 1, ready to broadcast / receive on FF:FF:FF:FF:FF:FF
• midi2::Device wired with typed callbacks; ByteStreamConverter active per transport (group 0 = BLE, group 1 = ESP-NOW)

Showcase loop every 350 ms:

Step	Bytes emitted	Where it goes
Note Off (previous note)	0x80 / note / 0x00	BLE notify + ESP-NOW broadcast
Note On (next scale degree)	0x90 / note / 0x60	BLE notify + ESP-NOW broadcast
CC #1 sweep	0xB0 / 0x01 / value	BLE notify + ESP-NOW broadcast

Scale walked is C major (60, 62, 64, 65, 67, 69, 71, 72); value for CC #1 increments by 16 per step and wraps after the octave.

Per inbound packet (any MIDI 1.0 byte stream on either transport, uplifted to UMP MT 0x2):

[NoteOn  ] BLE   g=0 ch=1  note=60  vel=0x6000
[NoteOff ] BLE   g=0 ch=1  note=60  vel=0x0000
[CC #1   ] ESPNW g=1 ch=1  val=0xFFFFFFFF

Velocity / value widths reflect the 7-bit to 16-bit / 32-bit upscale done by the dispatch layer; the wire side stays MIDI 1.0.

License

MIT, inherits parent midi2cpp LICENSE. ESP32_Host_MIDI is also MIT. Board reference images and PDFs under board/ are © Espressif Systems, redistributed for documentation purposes.