Restores the April-2026 "uSEQ-Celium" functionality (browser → uSEQ
hardware + CV expander over USB Web Serial) as a first-class Manifold
Outputs backend, and re-vendors the RP2040 firmware into the repo.
- protocol v2 (uSEQ-CV): firmware/useq-celium/shared/protocol.h is the
single source of truth, mirrored by manifold/src/backends/useq-protocol.ts.
26-byte OUTPUT frame, 11×u16 CV (12-bit) + 3-gate bitfield + XOR; fixed
topology; host-agnostic so the MEMLNaut RP2350 can emit identical bytes.
Spec in docs/useq-celium/protocol.md.
- firmware/useq-celium/{main,expander}: PlatformIO RP2040 firmware rewritten
to v2 from the real April pin maps (expander I2C addr 0x10).
- UseqCvBackend (id cvgate): Web Serial connect/identify/disconnect, 100 Hz
stream, per-channel dead-zone, gate thresholding; modeled on midi-backend.
Per-output CvSpec (channel + gateThreshold) on MFParam; config UI in
OutputsBackendConfig + BackendAdvanced; new "CV / uSEQ" top-dock mode.
- bun-test for the protocol frame layout; MAP.md updated.
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