b5584454b3
If the device isn't seen as a MIDI input (USB endpoint pressure from drive+serial+HID+MIDI), boot.py disables the unused HID interface and enables usb_midi — copy it on and power-cycle. Bundled into pm_k1_circuitpy.zip; documented in the README. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
79 lines
4.9 KiB
Markdown
79 lines
4.9 KiB
Markdown
# PM_K‑1 "Kit" — CircuitPython edition (USB drive + editor)
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The **CircuitPython** firmware for the 52Pi EP‑0172 Pico kit. Unlike the MicroPython version
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(`../pico/main.py`), this makes the Pico mount as a **USB drive (`CIRCUITPY`)** that carries the
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firmware and your tracks — so you can edit on the web and reprogram it without Thonny. It runs the
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same program‑string language as <https://metronome.varasys.io>.
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> **Status: experimental, phase 1.** This drives the screen/touch/joystick/buzzer and reads your
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> grooves from `programs.json`. The editor's one‑click "Save to device" and USB‑MIDI audio‑to‑computer
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> are landing in later phases. The simpler **MicroPython** firmware (`../pico/main.py`) remains the
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> rock‑solid fallback — and the Pico can't be bricked (BOOTSEL → drag a MicroPython `.uf2` back).
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## Install
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1. **Flash CircuitPython:** hold **BOOTSEL**, plug in, and drop the CircuitPython `.uf2` for your board
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onto the `RPI‑RP2` drive (<https://circuitpython.org/board/raspberry_pi_pico/> — or the Pico 2 / W
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build). It reboots and a **`CIRCUITPY`** drive appears.
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2. **Copy everything from the bundle** onto `CIRCUITPY` (drag‑and‑drop — it's a normal drive now):
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- `code.py` (this firmware — runs on boot)
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- `programs.json` (your grooves)
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- `font_s.bin`, `font_m.bin`, `font_l.bin` (the anti‑aliased fonts — kept as files to save RAM)
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- `editor.html` (an offline copy of the web editor, so the drive carries its own programmer)
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3. It starts immediately. Editing `programs.json` (or re‑saving it from the editor) makes CircuitPython
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**auto‑reload** with the new tracks.
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## Play through the computer's speakers (USB-MIDI)
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The board also shows up as a **USB-MIDI** device and sends a note on every click (a GM drum note per
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lane, velocity by accent). Open the [editor](https://metronome.varasys.io/editor.html) in **Chrome/Edge**,
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click **🎹 Device audio**, grant MIDI access, then press play *on the device* — the editor voices the
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groove through its full synth, out your computer's speakers, locked to the device's clock. The button
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shows the connected device's name and pulses green on each note; set `MUTE_BUZZER = True` in `code.py`
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if you'd rather silence the on-board buzzer while doing this.
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If the editor says **no MIDI input is connected**, copy **`boot.py`** onto `CIRCUITPY` too and
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**power-cycle** the Pico (`boot.py` only runs on a full reset). It frees a USB endpoint (drops the
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unused HID interface) so the MIDI port is guaranteed to appear alongside the drive.
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## Controls (same as the MicroPython build)
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- **Touch:** on‑screen `◀◀ / ▶ / ▶▶` (prev · play/stop · next) and `− / TAP / +`.
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- **Joystick:** up/down = tempo, left/right = previous/next groove.
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- **Button A (GP15)** play/stop · **Button B (GP14)** tap tempo.
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- **RGB LED** flashes each beat; **buzzer** clicks (accent/normal/ghost).
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## programs.json
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```json
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{ "title": "PolyMeter",
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"programs": [ { "name": "Four on the floor", "prog": "t120;kick:4;snare:4=.x.x;hatClosed:4/2" } ] }
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```
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Each `prog` is a program string from the web editor. Add/replace entries and save — the device reloads.
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**Easiest way to (re)program it:** in the editor (the web app, or the `editor.html` on the drive), build a
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set list, then the set‑list **⋯** menu → **📟 Save to device** → pick the `CIRCUITPY` drive. In Chrome/Edge it
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writes `programs.json` straight onto the drive (the Pico auto‑reloads); elsewhere it downloads the file to drag
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on. **📥 Load from device** reads a `programs.json` back into a new set list.
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## Calibration (flip flags at the top of `code.py`)
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- **Red/blue swapped:** flip `MADCTL` between `0x48` (default) and `0x40`.
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- **Colours look negative:** toggle `INVERT_COLORS`.
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- **Taps land wrong:** set `TOUCH_DEBUG = True`, watch the serial output, then set
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`TOUCH_SWAP_XY` / `TOUCH_INVERT_X` / `TOUCH_INVERT_Y`.
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- **Joystick reversed:** toggle `JOY_INVERT_X` / `JOY_INVERT_Y`.
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- **Computer audio:** `MIDI_ENABLED` (default on) sends the MIDI notes; `MUTE_BUZZER` silences the buzzer.
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- **LED too bright / too dim:** change `LED_BRIGHTNESS` (0..1, default 0.15).
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- **Screen tearing:** the SPI panel has no tearing-effect sync; `SPI_BAUD` (default 62.5 MHz) is pushed fast
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to minimise it — lower it only if the display is unstable.
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- **Screen blank / garbled:** the panel lot may differ; drop `SPI_BAUD`, and if it's a 240×320 ILI9341
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instead of the 320×480 ST7796, the init/size need changing (this targets the 320×480 you have).
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- **RGB LED** is driven by the core `neopixel_write` module — no library to install. If it stays dark,
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your CircuitPython build is unusually missing that module (everything else still works).
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If `code.py` ever errors, CircuitPython prints the traceback **on the screen and over USB serial** —
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copy that to me and I'll fix it.
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The fonts are the same baked anti‑aliased blobs as the MicroPython build (see `../pico/gen_font.py`).
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