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metronome/pico-cp/README.md
Me Here 7d743c18a1 PM_K-1: appliance model — push-programming over USB-MIDI, on-device practice log, swing fix 
Firmware (pico-cp/): the Pico now owns its filesystem by default (boot.py), so it can save the
practice log and write editor-pushed set lists; the drive is read-only to the computer, which also
protects the firmware. Hold button A at power-on for editor mode (drive writable; universal drag).
  - Replaced the on-screen touch buttons with an on-device PRACTICE LOG (time · BPM · duration ·
    track), newest-first, persisted to /history.json next to programs.json. Plays < 5s aren't logged;
    tap a row twice to delete it. Real timestamps once the editor syncs the clock.
  - USB-MIDI SysEx receiver: clock-set (0x01 -> RTC) and program-push (0x10 -> write programs.json,
    reload, ACK/NAK). disable autoreload so our own writes never self-restart.
  - Fixed swing: the parser was discarding the 's' flag, so /2s never swung. Now the scheduler uses a
    per-step duration with long-short (2:1, SWING_RATIO 2/3) pairs on even subdivisions, matching the
    web engine. Verified: ride:4/2s -> 266/133ms vs straight 200/200.

Editor (editor.html): requestMIDIAccess({sysex:true}); Save to device now pushes programs.json as
SysEx to the device (+ clock sync), waits for ACK, shows "Saved ✓", and falls back to downloading the
file (drag onto the drive in editor mode) when no device answers. Heartbeat also keeps the clock synced.
Web MIDI works in Chromium AND Firefox; the drag fallback covers any browser/OS incl. Safari.

Docs (pico-cp/README, info-kit, README) updated for the two modes, push programming, and the log.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-29 00:38:08 -05:00

5.2 KiB
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PM_K‑1 "Kit" — CircuitPython edition (USB drive · push programming · MIDI audio · practice log)

The CircuitPython firmware for the 52Pi EP‑0172 Pico kit, set up as a self‑contained appliance. It runs the same program‑string language as https://metronome.varasys.io. The simpler MicroPython firmware (../pico/main.py) stays as a rock‑solid fallback — and the Pico can't be bricked (BOOTSEL → drag a MicroPython .uf2 back).

What it does: drives the 3.5″ touchscreen with a lanes/pads display + anti‑aliased text, plays the buzzer + RGB beat light, logs your practice to /history.json, accepts new set lists pushed from the web editor over USB‑MIDI, and plays through your computer's speakers over USB‑MIDI.

Two power‑on modes (set by boot.py)

  • Appliance mode — default (just plug in / power up). The firmware owns the filesystem, so it saves your practice log and writes set lists the editor pushes over USB‑MIDI. The drive is then read‑only to the computer — which also protects the firmware from accidental deletion.
  • Editor mode — hold BUTTON A while plugging in. The drive is writable by the computer, so you can drag programs.json / code.py / fonts on from any OS or browser (the universal fallback). Reset afterwards to return to appliance mode.

Install

  1. Flash CircuitPython: hold BOOTSEL, plug in, drop the CircuitPython .uf2 onto RPI‑RP2 (https://circuitpython.org/board/raspberry_pi_pico/ — Pico 2 / W builds also fine). A CIRCUITPY drive appears.
  2. Copy the whole bundle onto CIRCUITPY: boot.py, code.py, programs.json, font_s.bin / font_m.bin / font_l.bin, editor.html (offline editor), and the helper scripts.
  3. Power‑cycle (so boot.py takes effect). It boots into appliance mode and runs.

Program it from the web (push over USB‑MIDI)

In the editor (Chrome / Edge / Firefox), build a set list → set‑list ⋯ menu → 📟 Save to device. The editor sends it to the Pico over USB‑MIDI (SysEx); the firmware writes /programs.json, reloads, and acknowledges — the editor shows Saved ✓. 📥 Load from device reads it back.

Universal fallback (any browser / OS, even Safari): Save to device downloads programs.json when no device answers — boot the Pico in editor mode (hold A) and drag the file onto the CIRCUITPY drive.

Play through the computer's speakers

The Pico is a USB‑MIDI device and sends a note per click (GM drum note per lane, velocity by accent). In the editor click 🎹 Device audio, grant MIDI access, and press play on the device — the editor voices the groove through its full synth, out your speakers, locked to the device's clock. While a host is listening the screen shows a green MIDI badge and the buzzer auto‑mutes (the computer plays instead). The editor also syncs the device clock, so the practice log gets real wall‑clock timestamps.

Controls & the practice log

  • Joystick: up/down = tempo, left/right = previous/next groove.
  • Button A (GP15): play / stop. Button B (GP14): tap tempo.
  • Touchscreen: the bottom of the screen shows the practice log (time · BPM · duration · track) — newest first. Plays under 5 s aren't logged. Tap a row to arm it (turns amber), tap again to delete.
  • RGB LED flashes the beat (amber accent / cyan normal / violet ghost); the buzzer clicks to match.
  • The log is saved to /history.json (next to programs.json) in appliance mode and survives power‑cycles.

programs.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 editor (tempo, lanes, patterns, /2 subdivision, /2s swing, (3,8) Euclid, ~ polymeter, @-3 dB). The push above is the easy way to update it.

Calibration (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, read the raw coords over USB serial, then set TOUCH_SWAP_XY / TOUCH_INVERT_X / TOUCH_INVERT_Y.
  • Joystick reversed: toggle JOY_INVERT_X / JOY_INVERT_Y.
  • Computer audio: MIDI_ENABLED (default on); MUTE_BUZZER forces the buzzer off even standalone.
  • LED too bright/dim: LED_BRIGHTNESS (0..1, default 0.15).
  • Screen tearing: SPI panels have no tearing‑effect sync; SPI_BAUD (default 62.5 MHz) is pushed fast to minimise it — lower only if unstable.
  • Blank / garbled: the panel lot may differ; drop SPI_BAUD, and if it's a 240×320 ILI9341 rather than the 320×480 ST7796, the init/size need changing (this targets the 320×480 you have).
  • RGB LED uses the core neopixel_write (no library to install).

If code.py ever errors, CircuitPython prints the traceback on the screen and over USB serial — send me that. The fonts are the baked anti‑aliased blobs from ../pico/gen_font.py. protect-firmware.sh (hide the firmware files) is mainly for editor mode — appliance mode already keeps the drive read‑only.