AMYBOARD_USB_HOST: one-off variant with USB MIDI host + UART REPL

[bwhitman]

New board variant for AMYboard that runs the USB port as a USB MIDI host (like Tulip CC) instead of the TinyUSB CDC + gadget-MIDI device, for using AMYboard with a MIDI keyboard/controller plugged directly into its USB port.

The REPL moves to UART0 — the same pins the stderr console already uses — so you control the board with a USB-serial dongle on the UART header.

What's in here

• tulip/amyboard/boards/AMYBOARD_USB_HOST/ — new board dir. Identical config to AMYBOARD (same sdkconfig list, partition table, frozen manifest) except MICROPY_HW_ENABLE_UART_REPL=1, BOARD_DEFINITION1=AMYBOARD_USB_HOST, and it compiles ../esp32s3/usb_host.c.
• tulip/esp32s3/usb_host.c/h — new USB_HOST_MIDI_ONLY guards (defined when AMYBOARD is) compile out the HID keyboard/mouse/lvgl handling, leaving the MIDI host in/out paths. TULIP builds are unchanged (guards are no-ops there).
• tulip/amyboard/main.c — variant skips TinyUSB device init and starts the run_usb host task instead (core 1, same shape as Tulip); defines tulip_ready, set in tulip_amyboard_start once AMY is up, which gates host MIDI → AMY.
• tulip/shared/amy_connector.c — variant drops AMY_MIDI_IS_USB_GADGET and enables Tulip's send_usb_midi_out path, so tulip_send_midi_out reaches the attached USB MIDI device. DIN MIDI (UART1, TRS A/B) is unchanged.

Notes

• The TinyUSB device stack is still compiled (amy_midi.c references tud_midi_* whenever AMYBOARD is defined) but never initialized — verified that every tud_* call short-circuits safely in that state (tusb_inited() / TU_VERIFY(ep_in) / empty fifos). This avoids any change to the amy submodule.
• tulip.board() still returns "AMYBOARD", so _boot.py / start_amy() / sketch flow run unchanged.
• The web editor's gadget-MIDI sysex protocol obviously doesn't apply to this variant; use the UART REPL.
• Not added to any release workflow — build locally with idf.py -DMICROPY_BOARD=AMYBOARD_USB_HOST build in tulip/amyboard, then python fs_create.py amyboard from tulip/ for the full image (dist/amyboard-full-AMYBOARD_USB_HOST.bin).

Verified

• AMYBOARD_USB_HOST builds clean; full 16MB image assembles (fs_create picks up the board name automatically).
• Stock AMYBOARD and TULIP4_R11 still build clean with these changes.

🤖 Generated with Claude Code

[github-actions]

🔌 AMYboard PR preview

Editor + flasher: https://amyboard-pr-1147.vercel.app/editor/

This preview bundles this PR's firmware — its flasher only flashes this build (not the release). Rebuilt on every push; removed when the PR closes.

The hardware CI has been kicked off and should return within a few minutes, stand by!

[github-actions]

🌷 Tulip Web PR preview

Tulip Web: https://tulip-pr-1147.vercel.app/run/

Flash a Tulip to this build: on-device run tulip.upgrade(pr=1147).

Rebuilt on every push; removed when the PR closes.

[github-actions]

🎛️ HW CI (physical bench)

AMYboard (USB-MIDI + AMY zP → audio; built-in tones + AMYboard World sketches acid/house/woodpiano over the SysEx control API): ✅ PASS — flashed this PR’s firmware; all checks matched the references.

Tulip (TULIP4_R11; serial-REPL audio + WiFi screenshot): ✅ PASS — flashed this PR’s firmware; all checks matched the references.

⬇️ Artifacts: recordings · screenshot · serial logs · run logs

_{Self-hosted bench. Audio spectral-compared to ref/hwci_basic.wav, the AMYboard World sketch refs (ref/{acid_generator,house_generator,woodpiano}.wav) + ref/tulip_basic.wav; Tulip screenshot pixel-compared to ref/tulip_screenshot.png. Both analog outs share one capture card, so the tests run sequentially.}