Initial design: ESP32-S3 presence sensor with camera, mmWave, PIR, temp/humidity, light

- KiCad schematic and PCB layout (45x35mm board)
- Full BOM with JLCPCB part numbers
- ESPHome firmware configuration
- 3D-printable wall-mount enclosure (OpenSCAD + STL)
- Pin mapping and power budget documentation

README.md

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+# ESP32-S3 Presence Sensor
+
+Compact wall-mount presence sensor with camera, mmWave radar, PIR, temperature/humidity, and ambient light sensing. Designed for Home Assistant via ESPHome.
+
+## Features
+- **5MP Camera** (OV5640, 120° wide-angle) - video stream to HA
+- **24GHz mmWave Radar** (LD2410C) - presence detection even when still
+- **PIR Sensor** (AM312) - instant motion trigger
+- **Temp/Humidity** (SHT41) - ±0.2°C accuracy
+- **Light Sensor** (BH1750) - 1-65535 lux
+- **USB-C powered** - any 1A+ charger
+- **~45x35mm PCB** - wall mountable
+
+## How Detection Works
+
+```
+Motion event:
+  PIR (AM312) ──→ instant trigger (ms response)
+       │
+       ▼
+  mmWave (LD2410C) ──→ sustained presence tracking
+       │                (detects breathing/typing)
+       ▼
+  Combined "Occupancy" ──→ true if either sensor active
+                           30s delay before "unoccupied"
+```
+
+PIR catches fast motion immediately. mmWave confirms someone is still in the room even when sitting perfectly still. The combined sensor gives zero false-offs.
+
+## Project Files
+
+| File | Description |
+|------|-------------|
+| `presence-sensor.kicad_pro` | KiCad project file |
+| `presence-sensor.kicad_sch` | Schematic |
+| `PIN_MAPPING.md` | GPIO assignments and power budget |
+| `BOM.csv` | Bill of materials with JLCPCB part numbers |
+| `esphome-presence-sensor.yaml` | ESPHome firmware config |
+
+## Build Instructions
+
+### 1. Order PCBs
+- Open project in KiCad 8+
+- Complete PCB layout (place components, route traces)
+- Generate Gerbers: File → Plot → Gerber
+- Upload to [JLCPCB](https://jlcpcb.com)
+- Enable SMD assembly, upload BOM.csv
+
+### 2. Order Modules (plug-in, not soldered by JLCPCB)
+- OV5640 camera module (24-pin 0.5mm FPC, wide-angle 120°)
+- HLK-LD2410C mmWave radar module
+- AM312 mini PIR sensor
+
+### 3. Assembly
+- Solder LD2410C to 1.27mm header
+- Solder AM312 to 2.54mm header
+- Connect OV5640 via FPC cable
+
+### 4. Flash Firmware
+```bash
+# Install ESPHome
+pip install esphome
+
+# Create secrets.yaml
+cat > secrets.yaml << EOF
+wifi_ssid: "your-wifi"
+wifi_password: "your-password"
+api_key: "generate-a-key"
+ota_password: "your-ota-password"
+fallback_password: "your-fallback"
+EOF
+
+# Flash via USB-C (hold BOOT, press RESET, release BOOT)
+esphome run esphome-presence-sensor.yaml
+```
+
+### 5. Add to Home Assistant
+- ESPHome auto-discovers the device
+- Settings → Devices & Services → ESPHome → Configure
+
+## Cost Per Board
+
+| Item | Cost |
+|------|------|
+| PCB fabrication (5pcs) | ~$8 total |
+| SMD assembly | ~$12/board |
+| Components on PCB | ~$5.50/board |
+| OV5640 camera module | ~$3.50 |
+| LD2410C radar | ~$2.50 |
+| AM312 PIR | ~$0.50 |
+| **Total per board** | **~$32** |
+
+## Design Notes
+
+### Antenna Clearance
+- ESP32-S3 antenna extends past board edge
+- No copper pour under antenna area (top or bottom)
+- Keep antenna away from LD2410C radar module
+
+### Thermal
+- SHT41 placed on board edge, away from ESP32 heat
+- -1.5°C offset in ESPHome config (calibrate after testing)
+- Enclosure should have ventilation slots near SHT41
+
+### mmWave Orientation
+- LD2410C mounted perpendicular to wall for widest room coverage
+- Detection cone is ~60° in each direction
+- Optimal height: 1.2-1.5m from floor
+
+### Camera
+- OV5640 connects via 24-pin FPC flex cable
+- Camera module sits at top of enclosure, angled slightly down
+- 120° wide-angle lens covers most of a room from wall mount