# Phase 1: ESP32 Firmware - Context

**Gathered:** 2026-04-03
**Status:** Ready for planning

<domain>
## Phase Boundary

ESP32-C3 SuperMini firmware that drives two LED strips (WS2801 160 LEDs via SPI, SK6812 300 LEDs via RMT/RGBW) and accepts named animation commands over UDP/JSON from a Raspberry Pi. The ESP32 executes animations autonomously — no frame streaming.

</domain>

<decisions>
## Implementation Decisions

### Animation Design
- **D-01:** Animations use a palette-based color system with full RGBW support. Each animation accepts a color palette (1-N colors as RGBW arrays) plus effect-specific parameters (speed, intensity, direction).
- **D-02:** White channel (W) on SK6812 is auto-derived from RGB when not explicitly specified in the command. User can override W directly for warm/cool white effects.
- **D-03:** 8 initial animations: Chase, Pulse, Rainbow, Strobe, Color Wash, Breathe, Sparkle, Gradient Sweep. All must work on both strip types.
- **D-04:** Animation tick rate: 50fps (20ms per frame) as a FreeRTOS task. This is the animation engine update rate, not the LED refresh rate.

### JSON Protocol
- **D-05:** Flat JSON command structure: `{"zone":"schrank"|"wand"|"all", "animation":"chase", "params":{"speed":0.5, "intensity":1.0, "colors":[[255,0,128,0]]}}`. Zone field is mandatory.
- **D-06:** Additional commands: `{"cmd":"stop","zone":"all"}`, `{"cmd":"brightness","zone":"all","value":100}`, `{"cmd":"status"}` (returns JSON via UDP response).
- **D-07:** Unknown commands are ignored silently; errors logged to serial console for debugging.
- **D-08:** Protocol includes a `"v":1` version field in every command for future compatibility.

### Power & Safety
- **D-09:** Firmware-enforced brightness cap at 40% (configurable via JSON command, max 60%). Research flagged 27A peak at full brightness — dedicated 5V supplies per strip required.
- **D-10:** On WiFi disconnect: continue running the last animation. On reconnect: accept new commands immediately. No auto-off timeout.
- **D-11:** Startup behavior: boot with a subtle breathing animation (low brightness) to indicate firmware is alive and WiFi is connecting.

### Development Setup
- **D-12:** PlatformIO with Arduino framework. NeoPixelBus (RMT) for SK6812, hardware SPI for WS2801.
- **D-13:** ArduinoJson v7 for JSON parsing, AsyncUDP for WiFi command reception.
- **D-14:** Serial debug output for development. No OTA in Phase 1 — flash via USB.

### Claude's Discretion
- FreeRTOS task priorities and stack sizes
- Exact GPIO pin assignments (validate on hardware — ESP32-C3 SuperMini pinout constraints)
- DMA buffer sizing for RMT to mitigate WiFi interrupt interference
- WiFi reconnection strategy and timing

</decisions>

<canonical_refs>
## Canonical References

**Downstream agents MUST read these before planning or implementing.**

### Project Context
- `.planning/PROJECT.md` — Project vision, hardware specs (WS2801 160 LEDs Schrank, SK6812 300 LEDs Wand, ESP32-C3 SuperMini)
- `.planning/REQUIREMENTS.md` — FW-01 through FW-05 requirements

### Research
- `.planning/research/STACK.md` — NeoPixelBus RMT, ArduinoJson, PlatformIO recommendations
- `.planning/research/ARCHITECTURE.md` — Component boundaries, FreeRTOS task structure, data flow
- `.planning/research/PITFALLS.md` — WiFi+RMT coexistence on single-core C3, SK6812 RGBW 4-byte framing, power budget

</canonical_refs>

<code_context>
## Existing Code Insights

### Reusable Assets
- None — greenfield project, no existing code

### Established Patterns
- None — first phase establishes firmware patterns

### Integration Points
- UDP port (to be defined) for Pi-to-ESP communication
- JSON protocol schema must be documented for Phase 2 (Pi-side transport client)

</code_context>

<specifics>
## Specific Ideas

- Hardware: ESP32-C3 SuperMini with WS2801 5m/160 LEDs (U-turn around Schrank) and SK6812 5m/300 LEDs (along wall)
- Both strips on one ESP32-C3 via different GPIO pins (SPI for WS2801, RMT for SK6812)
- Research warns: WiFi interrupts can corrupt SK6812 RMT timing on single-core C3 — must validate with `WIFI_PS_NONE` and proper DMA buffer sizing on day 1
- 1000uF capacitor at each strip input recommended

</specifics>

<deferred>
## Deferred Ideas

None — discussion stayed within phase scope (auto mode)

</deferred>

---

*Phase: 01-esp32-firmware*
*Context gathered: 2026-04-03*