1.9 KiB
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/specs/useq-cv-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 |
|---|---|---|---|
| CV1–CV3 | main | 21, 20, 19 | PWM (11-bit) |
| GATE1–GATE3 | main | 18, 17, 16 | digital |
| CV4–CV11 | expander | 13,14,10,11,8,7,5,3 | PWM (11-bit) |
The main board forwards CV4–CV11 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/specs/useq-cv-protocol.md.