46 lines
1.9 KiB
Markdown
46 lines
1.9 KiB
Markdown
# uSEQ-CV firmware
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Turns a [uSEQ](https://www.emutelabinstruments.co.uk/useq/) module (+ its CV
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expander) into a USB→CV/gate converter driven by the Manifold browser app's **CV
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output backend** (or, in future, the MEMLNaut RP2350 firmware directly). This is
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the restored + modernised descendant of the April-2026 "uSEQ-Celium" output mode
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(provenance in `docs/specs/useq-cv-protocol.md`).
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Both boards are RP2040 (Raspberry Pi Pico / uSEQ hardware) flashed with the
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Arduino-Pico (Earle Philhower) core. The wire protocol (v2) is defined once in
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`shared/protocol.h` and mirrored by `manifold/src/backends/useq-protocol.ts`.
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```
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shared/protocol.h uSEQ-CV v2 wire protocol (single source of truth)
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main/ uSEQ main module: USB serial → CV1..3 + GATE1..3, I2C → expander
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expander/ uSEQ expander: I2C slave → CV4..11 (8× PWM)
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```
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## Topology
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| Channel | Board | Pin(s) | Type |
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|------------|-----------|---------------|---------------|
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| CV1–CV3 | main | 21, 20, 19 | PWM (11-bit) |
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| GATE1–GATE3| main | 18, 17, 16 | digital |
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| CV4–CV11 | expander | 13,14,10,11,8,7,5,3 | PWM (11-bit) |
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The main board forwards CV4–CV11 to the expander over I2C (addr `0x10`, 400 kHz)
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and rescans every 2 s until the expander is found (hot-attach friendly).
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## Build / flash (PlatformIO)
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```bash
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# main board
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cd firmware/useq-celium/main && pio run -e main -t upload
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# expander board
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cd firmware/useq-celium/expander && pio run -e expander -t upload
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```
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(Or open each `.cpp` in the Arduino IDE with the RP2040 "Earle Philhower" core and
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add `firmware/useq-celium/shared` to the include path.)
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## Protocol smoke
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Hold the browser's **Identify** button (CV backend config) → both boards run an
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LED sweep, confirming the USB + I2C links end-to-end. Full frame layout:
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`docs/specs/useq-cv-protocol.md`.
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