# Project context

ESP32-S3 firmware for a desk-side Claude Code usage monitor. Two board variants are supported via a build-flag macro:

- **`-DBOARD_AMOLED_216`** → original Waveshare ESP32-S3-Touch-AMOLED-2.16 (CO5300, 480×480 square, CST9220 touch). Build env: `waveshare_amoled_216`.
- **`-DBOARD_AMOLED_18`** → Waveshare ESP32-S3-Touch-AMOLED-1.8 (SH8601, 368×448 portrait, FT3168 touch). Build env: `waveshare_amoled_18`.

`display_cfg.h` selects pins / typedefs / extern decls based on the macro. Per-board layout deltas (panel heights, fonts) are scoped with `#ifdef` in `ui.cpp` and `splash.cpp`.

Connects to a host daemon over BLE; daemon polls Anthropic API for usage data. This file is for future Claude Code sessions to bootstrap quickly. Read this first.

## Hardware (critical pins)

### AMOLED-2.16 (original)
- Display: **CO5300** AMOLED via QSPI (CS=12, SCLK=38, SDIO0..3=4..7, RST=2)
- Touch: **CST9220** via I2C (SDA=15, SCL=14, INT=11, addr=0x5A)
- PMU: **AXP2101** on same I2C bus (addr=0x34) — battery, USB VBUS, PWR button IRQ
- IMU: **QMI8658** on same I2C bus (addr=0x6B) — accelerometer for auto-rotation
- Buttons: GPIO 0 (left → Space/voice-mode), GPIO 18 (right → Shift+Tab/mode-toggle), AXP PKEY (middle → cycle screens; on splash → cycle animations)

### AMOLED-1.8 (newer port)
- Display: **SH8601** AMOLED via QSPI (CS=12, **SCLK=11** ← different!, SDIO0..3=4..7, RST routed via XCA9554 EXIO1)
- Touch: **FT3168** via I2C (SDA=15, SCL=14, INT=21, addr=0x38). Driven by minimal inline reader in `main.cpp` (FocalTech standard register layout — avoids vendoring the GPLv3 `Arduino_DriveBus` library).
- PMU: AXP2101 @ 0x34 (same chip as 2.16 — `XPowersLib` reused; battery is an optional kit add-on but PMU + charging circuitry are populated)
- IMU: QMI8658 @ 0x6B (same chip — initialized for I2C bus health, rotation logic disabled)
- IO expander: **XCA9554 / PCA9554** @ I2C 0x20. Gates LCD_RST, TP_RST, audio amp enable, and reads the PWR button. **`io_expander_init()` MUST run before `gfx->begin()` or `ft3168_init()`** — otherwise display/touch stay in reset and silently fail. PWR button is on EXIO4, active HIGH (verified empirically with the deleted `iox` serial debug command).
- Orientation: **fixed at 0°**. IMU auto-rotation is disabled; `rotate_strip()` / `handle_rotation_change()` are excluded via `#ifndef BOARD_AMOLED_18`.
- Buttons: GPIO 0 (BOOT → Space/voice-mode), XCA9554 EXIO4 (PWR → cycle screens; on splash → cycle animations). **No third button** (GPIO 18 button doesn't exist on this board).

## Architecture

```text
main.cpp        — setup(), loop(), button polling, FT3168 minimal reader (AMOLED-1.8), rotation flash (2.16 only)
display_cfg.h   — board-conditional pin defines, typedefs (PlatformDisplay = CO5300|SH8601), extern object decls
io_expander.{h,cpp} — XCA9554/PCA9554 wrapper (AMOLED-1.8 only): LCD/TP reset release + PWR button read
ui.{h,cpp}      — 3-screen UI (splash, usage, bluetooth); splash is touch-toggled, usage↔bluetooth via PWR button
splash.{h,cpp}  — 20×20 pixel-art animation engine. CELL = 24 (480²) for 2.16, 18 (360² centered) for 1.8
imu.{h,cpp}     — accelerometer-driven rotation tracker (returns 0..3). Result is ignored on AMOLED-1.8.
power.{h,cpp}   — AXP2101 wrapper (battery %, charging, VBUS, PWR button). PWR source is conditional: AXP PKEY IRQ on 2.16, XCA9554 EXIO4 polling on 1.8.
ble.{h,cpp}     — NimBLE peripheral: custom data service + HID keyboard
data.h          — UsageData struct
icons.h         — icon arrays. Battery (5×) are RGB565A8 with alpha; rest are raw RGB565.
logo.h          — 80×80 RGB565 logo
font_*.c        — pre-compiled LVGL 9 bitmap fonts (Tiempos 56/34, Styrene 48/28/24/20/16/14/12, Mono 32/18)
splash_animations.h — generated, do not hand-edit
```

## Build / flash

```bash
pio run -d firmware -e waveshare_amoled_216                                     # build 2.16 (default original)
pio run -d firmware -e waveshare_amoled_18                                      # build 1.8 (new port)
pio run -d firmware -e waveshare_amoled_18 -t upload --upload-port /dev/cu.usbmodem101   # flash 1.8 on macOS
pio run -d firmware -e waveshare_amoled_216 -t upload --upload-port /dev/ttyACM0         # flash 2.16 on Linux
```

If `pio` isn't on PATH: try `~/.platformio/penv/bin/pio` (Linux/macOS pio install) or `brew install platformio` on macOS.

Device path differs by OS: `/dev/cu.usbmodem*` on macOS, `/dev/ttyACM0` on Linux. Both expose the ESP32-S3 native USB-JTAG (no boot-mode dance needed).

## QA your own UI changes — don't ask the user

The firmware ships a `screenshot` serial command that dumps the LVGL framebuffer. `./screenshot.sh out.png [port]` captures a PNG sized to the active display (480×480 or 368×448). **Use this on every UI iteration** — Read the PNG with the Read tool, verify the change visually, iterate. Script auto-picks the macOS/Linux default port and falls back to pio's bundled Python if pyserial isn't on the system Python.

The boot screen is `SCREEN_SPLASH` and only advances on a physical button press, so a fresh flash will sit on the splash. To screenshot the screen you're actually editing without asking the user to press a button, **temporarily change the default boot screen** in `main.cpp` (search for `ui_show_screen(SCREEN_SPLASH);`) to `SCREEN_USAGE` / `SCREEN_CONTROLLER` / `SCREEN_BLUETOOTH`, do your iteration, then revert before committing.

## Critical gotchas

1. **CO5300 cannot rotate.** Its MADCTL only supports axis flips, not column/row exchange. Rotation is done by **CPU pixel remapping in `my_flush_cb`** in main.cpp. We use **PARTIAL render mode with strip rotation** (small 480×40 strips, fast). On rotation change → AMOLED brightness flash → force redraw.
2. **OPI PSRAM** required: `board_build.arduino.memory_type = qio_opi` in platformio.ini. Without this, `MALLOC_CAP_SPIRAM` returns NULL and the screen is black.
3. **pioarduino platform required.** GFX Library for Arduino needs Arduino Core 3.x (`esp32-hal-periman.h`), not the 2.x that standard `espressif32` ships. We pin `pioarduino/platform-espressif32` 55.03.38-1.
4. **LVGL 9 font patching.** `lv_font_conv` outputs LVGL 8 format. Must remove `#if LVGL_VERSION_MAJOR >= 8` guards, drop `.cache` field, add `.release_glyph`, `.kerning`, `.static_bitmap`, `.fallback`, `.user_data`. Without patching, fonts render invisible.
5. **Touch reading must be centralized.** CST9220's `getPoint()` does a full I2C transaction. Calling it from multiple places consumed each other's data and broke input. `touch_read()` is called once per loop in main.cpp; both LVGL `my_touch_cb` and `touch.cpp` read from shared `touch_pressed/touch_x/touch_y` state.
6. **CO5300 needs even-aligned flush regions.** `rounder_cb` enforces this.
7. **Touch `setSwapXY(true)` and `setMirrorXY(true, false)`** are the empirically-correct values for default rotation 0. IMU rotation logic doesn't change touch mapping (it does CPU-side rotation of the rendered pixels, so LVGL still thinks the display is portrait at 0°).
8. **LVGL RGB565A8 is planar.** `w*h` RGB565 pixels followed by `w*h` alpha bytes; `data_size = w*h*3`, `stride = w*2`. Use `init_icon_dsc_rgb565a8()` for icons that overlap non-uniform backgrounds (e.g. battery over splash). Lucide source PNGs are black-on-transparent — converter must tint to white or icons render invisible. See `tools/png_to_lvgl.js`.

## Icons

`tools/png_to_lvgl.js <input.png> <symbol> [W_MACRO] [H_MACRO] [--tint=RRGGBB | --no-tint]` converts an alpha PNG to RGB565A8. Default tint is white (`0xFFFFFF`) — necessary for Lucide PNGs. Splice output into `firmware/src/icons.h` and use `init_icon_dsc_rgb565a8()` in ui.cpp. Currently only the 5 battery icons use this format; the rest are still raw RGB565 baked over the panel background, fine because they live inside opaque zones.

## Splash animations

13 × 20×20 pixel-art creature animations sourced from
[claudepix.vercel.app](https://claudepix.vercel.app). Pipeline:

```bash
node tools/scrape_claudepix.js  # → tools/claudepix_data/*.json
node tools/convert_to_c.js      # → firmware/src/splash_animations.h
```

Each animation has a per-animation 10-color RGB565 palette. Cell values 0..9 index it. Default boot screen.

## User profile / preferences

See `~/.claude/projects/.../memory/` files for persistent context (user is an embedded-beginner senior dev, brand-conscious, prefers iterative UI refinement, dislikes me authoring my own art when third-party assets are intended). Always read those memory files at session start.

## Recent session highlights

- Migrated from Panlee SC01 Plus (480×320 IPS) to Waveshare 2.16" AMOLED (480×480 square). Full hardware/library swap.
- Added IMU auto-rotation, battery indicator, USB-state-aware screen switching.
- Added splash screen with scraped pixel-art animations and 3-button physical input layout.
- Fonts and icons re-scaled ~1.9× for the higher-DPI panel.
- All UI margins widened to 20px to clear the rounded display corners.
- Battery icons converted to RGB565A8 alpha so they blend cleanly over the splash animations.

## Daemon / host side

Bash daemon (`daemon/claude-usage-daemon.sh`) reads OAuth token, polls Anthropic API, sends JSON over BLE GATT. Run with `systemctl --user start claude-usage-daemon`. The unit file's `ExecStart` is the absolute path to the script — repoint it when switching between the worktree and the main checkout.

**Discovery & resilience:**

- Connects by name (`"Claude Controller"`) on first run, caches resolved MAC at `~/.config/claude-usage-monitor/ble-address`. ESP32 BLE addresses are factory-burned per-chip, so swapping any board invalidates the cache.
- On connect failure: cache is dropped AND device is removed from bluez (`bluetoothctl remove`) so the next scan won't re-pick a dead MAC. Multi-candidate scans pick `head -1` and let the failure cycle converge.
- `POLL_INTERVAL=60`, `TICK=5`. Inner loop wakes every 5s to detect disconnects fast; polls Anthropic when 60s elapsed OR when ESP fires a refresh request.

**GATT characteristics on service `4c41555a-...0001`:**

- `...0002` RX — daemon writes JSON usage payload here.
- `...0003` TX — firmware notifies ack/nack (daemon doesn't subscribe).
- `...0004` REQ — firmware fires `0x01` notify in `onSubscribe` if `has_received_data` is false. Daemon subscribes via `setsid bash -c "stdbuf -oL dbus-monitor … | awk …"`; awk drops a flag file the inner loop picks up. See the `feedback_dbus_monitor_pipe` memory for the three subtle gotchas (pipe buffering, busctl-exits race, `wait` blocking on pipeline jobs).