Phase 1: CircuitPython firmware (USB-drive edition) for the Kit

New pico-cp/ — a CircuitPython port of the PM_K-1 firmware so the Pico mounts as a
CIRCUITPY drive carrying its code + tracks (the MicroPython pico/main.py stays the
simple fallback):
  - pico-cp/code.py: displayio BusDisplay driving ST7796 via a custom init_sequence;
    smooth anti-aliased text via displayio Bitmap+Palette (reuses the baked font blobs);
    vectorio rects for dots/buttons; DIY GT911 touch (16-bit regs, edge-detected);
    pwmio buzzer, analogio joystick, digitalio buttons, optional neopixel RGB; the
    polymeter engine on a time.monotonic_ns scheduler. Reads /programs.json (falls back
    to baked defaults); CircuitPython auto-reloads on file change.
  - pico-cp/programs.json: the 23 default grooves. pico-cp/README.md: flash + calibrate.
  - build.sh/deploy.sh: bundle + serve /pm_k1_circuitpy.zip. info-kit.html: experimental
    'CircuitPython edition — USB drive' section.

Verified in CPython (stubbed displayio): init sequence well-formed, parser handles the
grooves incl. (3,8) euclid + @-4 gain, and code.py's actual make_text renders identical
smooth AA text. Hardware bits (panel/touch/MIDI) await on-board testing.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

build.sh

@@ -37,4 +37,9 @@ pathlib.Path("dist/embed.js").write_text(pathlib.Path("embed.js").read_text())
 print("copied embed.js")
 pathlib.Path("dist/pico-main.py").write_text(pathlib.Path("pico/main.py").read_text())  # PM_K-1 firmware, downloadable
 print("copied pico-main.py")
+import zipfile  # PM_K-1 CircuitPython drive bundle (download → unzip onto CIRCUITPY)
+with zipfile.ZipFile("dist/pm_k1_circuitpy.zip", "w", zipfile.ZIP_DEFLATED) as z:
+    for f in ("code.py", "programs.json", "README.md"):
+        z.write("pico-cp/" + f, f)
+print("zipped pm_k1_circuitpy.zip")
 PY

deploy.sh

@@ -48,6 +48,7 @@ for f in index.html editor.html player.html teacher.html stage.html micro.html s
 done
 cp "$DIST_DIR/embed.js" "$DEST_DIR/embed.js"; echo "  embed.js ($(stat -c '%s' "$DEST_DIR/embed.js") bytes)"
 cp "$DIST_DIR/pico-main.py" "$DEST_DIR/pico-main.py"; echo "  pico-main.py ($(stat -c '%s' "$DEST_DIR/pico-main.py") bytes)"  # PM_K-1 firmware download
+cp "$DIST_DIR/pm_k1_circuitpy.zip" "$DEST_DIR/pm_k1_circuitpy.zip"; echo "  pm_k1_circuitpy.zip ($(stat -c '%s' "$DEST_DIR/pm_k1_circuitpy.zip") bytes)"  # PM_K-1 CircuitPython bundle
 rm -f "$DEST_DIR/player-asbuilt.html"        # renamed to teacher.html
 rm -f "$DEST_DIR/concepts.html"              # Concepts is now the landing (/)
 # info-*.html are first-class pages again: each form factor has a lean widget page

info-kit.html

@@ -129,6 +129,26 @@
   </div>
 </details>
 
+<details class="spec">
+  <summary>CircuitPython edition — USB drive + editor (experimental)</summary>
+  <div class="spec-body">
+    <p class="sub">An alternative firmware that makes the Pico mount as a <b>USB drive</b> carrying the
+      firmware and your tracks (<code>programs.json</code>) — edit on the web and reprogram it without
+      Thonny. Coming next: one‑click "Save to device" and USB‑MIDI audio out to your computer's speakers.
+      The MicroPython firmware above stays the simple, rock‑solid option.</p>
+    <p>
+      <a class="dl" href="/pm_k1_circuitpy.zip" download>Download CircuitPython bundle ↓</a>
+      <a class="dl alt" href="https://codeberg.org/VARASYS/metronome/src/branch/main/pico-cp" target="_blank" rel="noopener">Source + README ↗</a>
+    </p>
+    <ol class="steps">
+      <li>Flash <b>CircuitPython</b> (<a href="https://circuitpython.org/board/raspberry_pi_pico/" target="_blank" rel="noopener">raspberry_pi_pico</a>)
+        via BOOTSEL → the <code>CIRCUITPY</code> drive appears.</li>
+      <li>Unzip the bundle onto <code>CIRCUITPY</code> (<code>code.py</code> + <code>programs.json</code>) — it's a normal drive, just drag them on.</li>
+      <li>It runs on boot; editing <code>programs.json</code> auto‑reloads the grooves. See the bundle's README for calibration flags.</li>
+    </ol>
+  </div>
+</details>
+
 <p class="sub" style="max-width:760px;margin:14px auto 0">Embed this widget elsewhere with one <code>&lt;div&gt;</code> + a script —
   see <a href="/embed.html">the embed docs</a>.</p>
 </main>

pico-cp/README.md

@@ -0,0 +1,55 @@
+# PM_K‑1 "Kit" — CircuitPython edition (USB drive + editor)
+
+The **CircuitPython** firmware for the 52Pi EP‑0172 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 program‑string 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 one‑click "Save to device" and USB‑MIDI audio‑to‑computer
+> are landing in later phases. The simpler **MicroPython** firmware (`../pico/main.py`) remains the
+> rock‑solid 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 `RPI‑RP2` drive (<https://circuitpython.org/board/raspberry_pi_pico/> — or the Pico 2 / W
+   build). It reboots and a **`CIRCUITPY`** drive appears.
+2. **Copy the files** onto `CIRCUITPY` (drag‑and‑drop — it's a normal drive now):
+   - `code.py`  (this firmware — runs on boot)
+   - `programs.json`  (your grooves)
+3. It starts immediately. Editing `programs.json` (or re‑saving it from the editor) makes CircuitPython
+   **auto‑reload** with the new tracks.
+
+## Controls (same as the MicroPython build)
+
+- **Touch:** on‑screen `◀◀ / ▶ / ▶▶` (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:** change `MADCTL = 0x40` to `0x48`.
+- **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`.
+- **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).
+- **No RGB LED:** the WS2812 needs the `neopixel` library on `CIRCUITPY/lib` (`circup install neopixel`)
+  — everything else works without it.
+
+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 anti‑aliased blobs as the MicroPython build (see `../pico/gen_font.py`).

pico-cp/programs.json

@@ -0,0 +1,97 @@
+{
+  "title": "PolyMeter",
+  "programs": [
+    {
+      "name": "Four on the floor",
+      "prog": "t120;kick:4;snare:4=.x.x;hatClosed:4/2"
+    },
+    {
+      "name": "Swing ride",
+      "prog": "t150;ride:4/2s;kick:4=X..x;snare:4=.x.x"
+    },
+    {
+      "name": "Purdie half shuffle",
+      "prog": "t92;kick:4/3=X....x...x..;snare:4/3=..gg.gX.gg.g;hatClosed:4/3=X.xX.xX.xX.x"
+    },
+    {
+      "name": "Samba (2/4)",
+      "prog": "t104;tomLow:2/4=x...X...;hatClosed:2/4;woodblock:2/4=X.xx.xX."
+    },
+    {
+      "name": "Nanigo (6/8 bembe)",
+      "prog": "t130;cowbell:4/3=X.xx.x.xx.x.;kick:4/3=X.....X.....;hatClosed:4/3=..x..x..x..x"
+    },
+    {
+      "name": "6/8 groove",
+      "prog": "t100;kick:3+3=x..x..;snare:3+3=...x..;hatClosed:3+3/2"
+    },
+    {
+      "name": "7/8 (2+2+3)",
+      "prog": "t130;kick:2+2+3=x..x..x;hatClosed:2+2+3/2"
+    },
+    {
+      "name": "5/4 (3+2)",
+      "prog": "t112;kick:3+2=x..x.;snare:3+2=..x..;hatClosed:3+2/2"
+    },
+    {
+      "name": "5 over 4 polyrhythm",
+      "prog": "t100;kick:4;claves:5~"
+    },
+    {
+      "name": "3 over 2 hemiola",
+      "prog": "t96;woodblock:2;cowbell:3~"
+    },
+    {
+      "name": "2 & 4 & 3 per bar",
+      "prog": "t100;kick:3;cowbell:2~;claves:4~"
+    },
+    {
+      "name": "Triplet hats",
+      "prog": "t100;kick:4;snare:4=.x.x;hatClosed:4/3"
+    },
+    {
+      "name": "Accents",
+      "prog": "t92;kick:4=X..X;snare:4=.X.X;hatClosed:4/2"
+    },
+    {
+      "name": "Tempo builder 80+",
+      "prog": "t80;woodblock:4;rmp80/4/4"
+    },
+    {
+      "name": "Gap trainer 2/2",
+      "prog": "t100;kick:4;hatClosed:4/2;tr2/2"
+    },
+    {
+      "name": "Intro - hats+kick",
+      "prog": "t88;kick:4=X.x.;hatClosed:4/2=gggggggg"
+    },
+    {
+      "name": "Groove in",
+      "prog": "t88;kick:4=X.x.;snare:4=.X.X;hatClosed:4/2"
+    },
+    {
+      "name": "Half-time shuffle",
+      "prog": "t92;kick:4/3=X....x...x..;snare:4/3=..gg.gX.gg.g;hatClosed:4/3=X.xX.xX.xX.x"
+    },
+    {
+      "name": "Build 92 to 120",
+      "prog": "t92;kick:4;snare:4=.X.X;hatClosed:4/2"
+    },
+    {
+      "name": "Four-floor (909)",
+      "prog": "t124;kick909:4;clap909:4=.X.X;hat909:4/2=.X.X.X.X"
+    },
+    {
+      "name": "Samba break",
+      "prog": "t116;tomLow:2/4=x...X...;hatClosed:2/4;woodblock:2/4=X.xx.xX."
+    },
+    {
+      "name": "Peak - 16ths",
+      "prog": "t132;kick:4=X..x;snare:4=.X.X;hatClosed:4/4"
+    },
+    {
+      "name": "Outro",
+      "prog": "t132;kick:4=X..x;hatClosed:4/2=gggggggg"
+    }
+  ]
+}