metronome/pico-cp/README.md
Me Here ec43c694a1 PM_K-1 CircuitPython: circle pad grid, small labels, dimmer LED, faster SPI
From on-board feedback (works well; minor tweaks):
  - Pad grid uses circles now: big circle on each beat (division), small on the
    subdivisions (vectorio.Circle — native, no extra cost), coloured/lit as before.
  - Lane labels use a new small font (font_s.bin, ~12px via gen_font.py) so they're
    half-size and show more of the voice name (e.g. 'hatClos').
  - LED was blinding -> LED_BRIGHTNESS scale (default 0.15) applied on every write.
  - Residual tearing -> SPI back to 62.5 MHz (vendor speed; smaller tear window on a
    panel with no tearing-effect pin). Both are CONFIG flags.
Verified by rendering the full scene headless. font_s.bin added to gen_font.py + bundle.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-28 22:07:00 -05:00

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# PM_K1 "Kit" — CircuitPython edition (USB drive + editor)
The **CircuitPython** firmware for the 52Pi EP0172 Pico kit. Unlike the MicroPython version
(`../pico/main.py`), this makes the Pico mount as a **USB drive (`CIRCUITPY`)** that carries the
firmware and your tracks — so you can edit on the web and reprogram it without Thonny. It runs the
same programstring language as <https://metronome.varasys.io>.
> **Status: experimental, phase 1.** This drives the screen/touch/joystick/buzzer and reads your
> grooves from `programs.json`. The editor's oneclick "Save to device" and USBMIDI audiotocomputer
> are landing in later phases. The simpler **MicroPython** firmware (`../pico/main.py`) remains the
> rocksolid fallback — and the Pico can't be bricked (BOOTSEL → drag a MicroPython `.uf2` back).
## Install
1. **Flash CircuitPython:** hold **BOOTSEL**, plug in, and drop the CircuitPython `.uf2` for your board
onto the `RPIRP2` drive (<https://circuitpython.org/board/raspberry_pi_pico/> — or the Pico 2 / W
build). It reboots and a **`CIRCUITPY`** drive appears.
2. **Copy everything from the bundle** onto `CIRCUITPY` (draganddrop — it's a normal drive now):
- `code.py` (this firmware — runs on boot)
- `programs.json` (your grooves)
- `font_s.bin`, `font_m.bin`, `font_l.bin` (the antialiased fonts — kept as files to save RAM)
3. It starts immediately. Editing `programs.json` (or resaving it from the editor) makes CircuitPython
**autoreload** with the new tracks.
## Controls (same as the MicroPython build)
- **Touch:** onscreen `◀◀ / ▶ / ▶▶` (prev · play/stop · next) and ` / TAP / +`.
- **Joystick:** up/down = tempo, left/right = previous/next groove.
- **Button A (GP15)** play/stop · **Button B (GP14)** tap tempo.
- **RGB LED** flashes each beat; **buzzer** clicks (accent/normal/ghost).
## programs.json
```json
{ "title": "PolyMeter",
"programs": [ { "name": "Four on the floor", "prog": "t120;kick:4;snare:4=.x.x;hatClosed:4/2" } ] }
```
Each `prog` is a program string from the web editor. Add/replace entries and save — the device reloads.
## Calibration (flip flags at the top of `code.py`)
- **Red/blue swapped:** flip `MADCTL` between `0x48` (default) and `0x40`.
- **Colours look negative:** toggle `INVERT_COLORS`.
- **Taps land wrong:** set `TOUCH_DEBUG = True`, watch the serial output, then set
`TOUCH_SWAP_XY` / `TOUCH_INVERT_X` / `TOUCH_INVERT_Y`.
- **Joystick reversed:** toggle `JOY_INVERT_X` / `JOY_INVERT_Y`.
- **LED too bright / too dim:** change `LED_BRIGHTNESS` (0..1, default 0.15).
- **Screen tearing:** the SPI panel has no tearing-effect sync; `SPI_BAUD` (default 62.5 MHz) is pushed fast
to minimise it — lower it only if the display is unstable.
- **Screen blank / garbled:** the panel lot may differ; drop `SPI_BAUD`, and if it's a 240×320 ILI9341
instead of the 320×480 ST7796, the init/size need changing (this targets the 320×480 you have).
- **RGB LED** is driven by the core `neopixel_write` module — no library to install. If it stays dark,
your CircuitPython build is unusually missing that module (everything else still works).
If `code.py` ever errors, CircuitPython prints the traceback **on the screen and over USB serial**
copy that to me and I'll fix it.
The fonts are the same baked antialiased blobs as the MicroPython build (see `../pico/gen_font.py`).