memlnaut-nisps/firmware/useq-celium/README.md
monkey-w1n5t0n 4656568d4f feat(manifold,firmware): restore uSEQ CV/gate as an Outputs backend
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.
2026-06-28 22:30:54 +02:00

1.9 KiB
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uSEQ-CV firmware

Turns a uSEQ module (+ its CV expander) into a USB→CV/gate converter driven by the Manifold browser app's CV output backend (or, in future, the MEMLNaut RP2350 firmware directly). This is the restored + modernised descendant of the April-2026 "uSEQ-Celium" output mode (provenance in docs/useq-celium/protocol.md).

Both boards are RP2040 (Raspberry Pi Pico / uSEQ hardware) flashed with the Arduino-Pico (Earle Philhower) core. The wire protocol (v2) is defined once in shared/protocol.h and mirrored by manifold/src/backends/useq-protocol.ts.

shared/protocol.h        uSEQ-CV v2 wire protocol (single source of truth)
main/                    uSEQ main module: USB serial → CV1..3 + GATE1..3, I2C → expander
expander/                uSEQ expander: I2C slave → CV4..11 (8× PWM)

Topology

Channel Board Pin(s) Type
CV1CV3 main 21, 20, 19 PWM (11-bit)
GATE1GATE3 main 18, 17, 16 digital
CV4CV11 expander 13,14,10,11,8,7,5,3 PWM (11-bit)

The main board forwards CV4CV11 to the expander over I2C (addr 0x10, 400 kHz) and rescans every 2 s until the expander is found (hot-attach friendly).

Build / flash (PlatformIO)

# main board
cd firmware/useq-celium/main && pio run -e main -t upload
# expander board
cd firmware/useq-celium/expander && pio run -e expander -t upload

(Or open each .cpp in the Arduino IDE with the RP2040 "Earle Philhower" core and add firmware/useq-celium/shared to the include path.)

Protocol smoke

Hold the browser's Identify button (CV backend config) → both boards run an LED sweep, confirming the USB + I2C links end-to-end. Full frame layout: docs/useq-celium/protocol.md.