Me Here 400d896518 Add PM_G-1 "Grid" form factor (Pimoroni Pico Scroll Pack) + Rust core/driver plan

New form factor: a plain RP2040 Pico + Pico Scroll Pack (PIM545) -- a 17x7
single-colour LED matrix + 4 buttons. The 7x17 matrix maps onto the editor's
lane x step pad grid.

- pico-scroll/: CircuitPython firmware (DEVICE_ID "G"). Engine/scheduler/SysEx/
  live-sync copied verbatim from pico-explorer (engine byte-identical, so it stays
  on the track-format conformance lineage); vendored bulk-framebuffer IS31FL3731
  driver (pins/map verified from pimoroni-pico); three LED views (Grid/Pendulum/BPM);
  4-button input. Audio over USB-MIDI (no onboard speaker); optional P_BUZZER.
- grid.html + info-grid.html: widget page (canvas mirrors the 3 LED views) + spec
  page with a ~$29 BOM.
- Registered in build.sh (precompile + ASCII assert + pm_g1_circuitpy.zip), deploy.sh,
  embed.js, embed.html, index.html gallery, and both editors' FW_PATHS (device id G).
- docs/rust-port.md: core/driver architecture (pm-core no_std engine+protocol; per-board
  drivers behind embedded-hal/embedded-graphics traits). CLAUDE.md + livesync-protocol.md
  note the new edition + device id.

Python firmware stays in parallel with Rust (no abandonment yet).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

2026-05-31 20:30:15 -05:00

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PM_G-1 "Grid" — CircuitPython edition (Pimoroni Pico Scroll Pack · RP2040)

The CircuitPython firmware for the Pimoroni Pico Scroll Pack (PIM545) on a plain Raspberry Pi Pico, set up as a self-contained appliance. Sibling to the PM_K-1 build in ../pico-cp/ and PM_X-1 in ../pico-explorer/ — same engine, same program strings, same programs.json, same web editor, same live-sync protocol.

This board is a 17 × 7 single-colour (white) LED matrix (IS31FL3731 over I²C) + 4 buttons (A/B/X/Y) — no touchscreen, no joystick, no RGB LED, and no onboard speaker. It's the smallest, most minimal form factor: the 7-row × 17-column grid is the editor's lane × step pad grid in miniature. Editing happens in the web editor with Live sync on; the device mirrors changes in real time and emits its own play/stop/bpm/sel deltas back.

Audio is over USB-MIDI — turn on the editor's 🎹 Device audio to hear the clicks through your computer's speakers. The Scroll Pack has no buzzer; if you solder a piezo to a free GPIO, set P_BUZZER near the top of app.py to that pin to get an on-device click.

Views (button B cycles)

View	What the 17 × 7 matrix shows
Grid (default)	Each lane is a row (top 7), each step a column; brightness = accent (bright) / normal / ghost (dim). A bright playhead column tracks the beat. Bars with ≤ 17 steps are centred one-column-per-step; longer bars are scaled to fit (multiple steps may share a column — no steps are dropped).
Pendulum	A single column bounces left↔right across the bar like a metronome arm, with a full-height flash on each beat (accent = brightest). Glanceable from across a room.
BPM	The current tempo as three 3 × 5 digits.

Controls

Button	Tap	Hold
A	play / stop	≥ 0.6 s: cycle view (Grid → Pendulum → BPM)
B	next track	≥ 0.6 s: next set list
X	tempo − 1	auto-repeat (after ~1.5 s the step grows to − 5)
Y	tempo + 1	auto-repeat (after ~1.5 s the step grows to + 5)

Tap tempo lives in the web editor; the built-in playlists (Styles / Practice / Song) are baked into firmware and your own set lists arrive in /programs.json over USB-MIDI. The mapping is deliberately simple (this is a UI prototype) — all four buttons and their pins are at the top of app.py, easy to re-bind.

Pinout (verified against the Pimoroni `pico_scroll` library)

Signal	Pico pin
Button A / B / X / Y	GP12 / GP13 / GP14 / GP15
Matrix I²C SDA / SCL	GP4 / GP5
IS31FL3731 address	`0x74`
(optional piezo)	any free GPIO → set `P_BUZZER`

Flashing

Hold BOOTSEL, plug the Pico in, and drag on CircuitPython for Raspberry Pi Pico (the same 10.2.x build the Kit uses). The drive remounts as CIRCUITPY.
Download /pm_g1_circuitpy.zip from https://metronome.varasys.io and unzip its contents onto CIRCUITPY (code.py, boot.py, app.mpy, programs.json, fonts/icons, editor.html).
Reset. By default the firmware owns the drive (appliance mode); hold button A while plugging in to make the drive writable again (editor mode).

The application is the precompiled app.mpy (the ~25 KB app.py source is too big to compile on-device without OOM). Firmware updates are one click from the editor (⋯ → Update firmware), pushed over USB-MIDI as an A/B update with automatic rollback — the device reports id G so the editor sends the Grid build. Unbrickable: BOOTSEL + drag a .uf2 always restores it.

Status

This is the CircuitPython prototype used to nail down the LED-grid UI on real hardware. The production firmware target is the native-Rust engine (one pm-core + per-board drivers — see docs/rust-port.md); the Python builds stay as the simple, no-toolchain option in parallel.

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