Initial KiCad project

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+# Custom PCB Design Specification: Midea AC Controller with BLE Beacon
+
+## Recommended ESP Module
+
+### 🏆 **Best Choice: ESP32-WROOM-32E or ESP32-WROOM-32**
+
+**Why ESP32 (not ESP8266 or ESP32-C6)?**
+- ✅ **Bluetooth BLE Support**: Required for beacon functionality
+- ✅ **Midea Component Compatibility**: Works with Arduino framework (ESP32-C6 uses ESP-IDF, incompatible)
+- ✅ **Excellent ESPHome Support**: Most mature and well-documented
+- ✅ **Dual Core**: Can handle WiFi + BLE + Midea communication simultaneously
+- ✅ **Multiple UARTs**: Can use hardware UART for Midea, software UART for debugging
+- ✅ **Good Memory**: 520KB SRAM, sufficient for both features
+
+### Module Options
+
+| Module | Size | Flash | RAM | Price | Recommendation |
+|--------|------|-------|-----|-------|----------------|
+| **ESP32-WROOM-32E** | 18×25.5mm | 4MB | 520KB | $$ | ⭐ **Best for custom PCB** |
+| **ESP32-WROOM-32** | 18×25.5mm | 4MB | 520KB | $$ | ⭐ Good alternative |
+| **ESP32-MINI-1** | 13.2×16.6mm | 4MB | 520KB | $$ | Compact option |
+| ESP32-C3 | 18×25.5mm | 4MB | 400KB | $ | RISC-V, less support |
+| ESP32-C6 | 18×25.5mm | 4MB | 512KB | $$ | ESP-IDF only, no Midea |
+
+**Recommended**: **ESP32-WROOM-32E** (most common, best support)
+
+---
+
+## PCB Design Requirements
+
+### Core Components
+
+1. **ESP32-WROOM-32E Module**
+   - 38 pins (19 per side)
+   - Requires 3.3V power
+   - Built-in antenna
+
+2. **Logic Level Shifter (3.3V ↔ 5V)**
+   - **TXB0104** (4-channel) or **74LVC245** (8-channel)
+   - Required for Midea AC communication (5V logic)
+   - Bidirectional for TX/RX
+
+3. **Power Supply**
+   - **AMS1117-3.3** or **LD1117-3.3** (3.3V regulator)
+   - Input: 5V (USB or external)
+   - Output: 3.3V @ 1A (ESP32 needs ~500mA peak)
+   - Decoupling capacitors: 10µF + 100nF
+
+4. **USB-to-Serial (Optional but Recommended)**
+   - **CP2102** or **CH340C** for programming/debugging
+   - Allows OTA updates via USB
+   - Auto-reset circuit for easy flashing
+
+5. **Midea AC Connector**
+   - **JST-XH 4-pin** or **USB Type-A** (depending on AC dongle)
+   - Pins: VCC (5V), GND, TX, RX
+
+6. **Status LEDs**
+   - Power LED (3.3V)
+   - WiFi status LED
+   - BLE status LED (optional)
+   - Midea communication LED (optional)
+
+7. **Reset Button**
+   - Reset ESP32
+   - Boot button (GPIO0) for flashing
+
+### Pin Assignment
+
+#### ESP32-WROOM-32E Pinout
+
+```
+Power:
+  VDD (Pin 1, 3, 14, 21, 22, 27, 28, 33, 42) → 3.3V
+  GND (Pin 2, 4, 13, 15, 20, 23, 26, 29, 34, 38, 40) → GND
+
+Midea UART (via Level Shifter):
+  GPIO17 (TX) → Level Shifter LV1 → HV1 → AC Dongle RX
+  GPIO16 (RX) → Level Shifter LV2 → HV2 → AC Dongle TX
+  GND → AC Dongle GND
+
+USB-to-Serial (if included):
+  GPIO1 (TX) → CP2102 RX
+  GPIO3 (RX) → CP2102 TX
+  GPIO0 (Boot) → CP2102 DTR (auto-reset)
+
+Status LEDs:
+  GPIO2 → WiFi Status LED
+  GPIO4 → BLE Status LED (optional)
+  GPIO5 → Midea Communication LED (optional)
+
+Buttons:
+  GPIO0 → Boot/Flash Button
+  EN → Reset Button
+
+Bluetooth:
+  Built-in (no external pins needed)
+```
+
+### Schematic Design
+
+#### Power Section
+```
+USB 5V → AMS1117-3.3 → 3.3V → ESP32 VDD
+                    ↓
+                  GND → Common Ground
+```
+
+#### Midea Communication Section
+```
+ESP32 GPIO17 (TX) → TXB0104 LV1 → HV1 → AC Dongle RX
+ESP32 GPIO16 (RX) → TXB0104 LV2 → HV2 → AC Dongle TX
+ESP32 GND → TXB0104 GND → AC Dongle GND
+ESP32 3.3V → TXB0104 LV
+External 5V → TXB0104 HV → AC Dongle VCC (if needed)
+```
+
+#### Level Shifter Configuration (TXB0104)
+- **VCCA (LV)**: 3.3V from ESP32
+- **VCCB (HV)**: 5V from USB or external
+- **OE (Output Enable)**: Connect to 3.3V (always enabled)
+- **A1 (LV1)**: ESP32 GPIO17 (TX)
+- **B1 (HV1)**: AC Dongle RX
+- **A2 (LV2)**: ESP32 GPIO16 (RX)
+- **B2 (HV2)**: AC Dongle TX
+
+---
+
+## PCB Layout Considerations
+
+### Layer Stackup (2-layer minimum, 4-layer recommended)
+
+**2-Layer:**
+- Top: Components, signal traces
+- Bottom: Ground plane, power traces
+
+**4-Layer (Recommended):**
+- Top: Components, signal traces
+- Layer 2: Ground plane
+- Layer 3: Power plane (3.3V)
+- Bottom: Ground plane, remaining signals
+
+### Design Rules
+
+1. **Power Traces**
+   - 3.3V: Minimum 0.5mm (20mil) width
+   - 5V: Minimum 0.5mm (20mil) width
+   - GND: Use ground planes where possible
+
+2. **Signal Traces**
+   - UART: 0.2mm (8mil) minimum
+   - Keep UART traces short (<50mm)
+   - Avoid crossing power traces
+
+3. **Component Placement**
+   - ESP32 module: Center of board
+   - Level shifter: Close to ESP32 and AC connector
+   - Power regulator: Near USB input
+   - Decoupling caps: Close to power pins (<5mm)
+
+4. **Antenna Clearance**
+   - Keep 15mm clearance around ESP32 antenna area
+   - No ground plane under antenna
+   - No components or traces near antenna
+
+5. **Thermal Considerations**
+   - Add thermal vias under power regulator
+   - Ensure adequate copper for heat dissipation
+
+### Board Size Recommendation
+
+- **Minimum**: 40mm × 50mm (fits ESP32 + essential components)
+- **Recommended**: 50mm × 60mm (comfortable spacing, room for connectors)
+- **With USB**: 50mm × 70mm (includes USB connector)
+
+---
+
+## Bill of Materials (BOM)
+
+### Essential Components
+
+| Component | Part Number | Quantity | Notes |
+|-----------|-------------|----------|-------|
+| ESP32 Module | ESP32-WROOM-32E | 1 | 4MB flash, built-in antenna |
+| Level Shifter | TXB0104PWR | 1 | 4-channel, TSSOP-14 |
+| 3.3V Regulator | AMS1117-3.3 | 1 | SOT-223 or SOT-89 |
+| USB-to-Serial | CP2102N | 1 | Optional, QFN-24 |
+| USB Connector | USB-B Micro | 1 | Optional, for programming |
+| AC Connector | JST-XH 4-pin | 1 | Or USB Type-A female |
+| Reset Button | Tactile Switch | 1 | 6×6mm |
+| Boot Button | Tactile Switch | 1 | 6×6mm (optional) |
+| Status LED | LED 0603 | 2-3 | Red/Green/Blue |
+| Resistors | 10kΩ 0603 | 2 | Pull-up for buttons |
+| Resistors | 220Ω 0603 | 2-3 | LED current limiting |
+| Capacitors | 10µF 0805 | 2 | Power decoupling |
+| Capacitors | 100nF 0603 | 5-10 | Decoupling |
+
+### Optional Components
+
+- **BLE Status LED**: Additional LED for Bluetooth status
+- **Midea Status LED**: LED to show AC communication
+- **Crystal**: 32.768kHz (if using RTC features)
+- **EEPROM**: For storing settings (ESP32 has built-in)
+
+---
+
+## ESPHome Configuration Template
+
+```yaml
+esphome:
+  name: midea-ac-controller
+  friendly_name: Midea AC Controller
+
+esp32:
+  board: esp32dev
+  framework:
+    type: arduino
+
+# Enable logging (can use software serial or disable)
+logger:
+  baud_rate: 115200  # Or 0 to disable
+
+# Enable Home Assistant API
+api:
+  encryption:
+    key: !secret api_encryption_key
+
+ota:
+  - platform: esphome
+    password: !secret ota_password
+
+wifi:
+  ssid: !secret wifi_ssid
+  password: !secret wifi_password
+  min_auth_mode: WPA2
+  ap:
+    ssid: "Midea AC Controller"
+    password: !secret fallback_password
+
+captive_portal:
+
+# Status LEDs
+binary_sensor:
+  - platform: status
+    name: "WiFi Status"
+    
+output:
+  - platform: gpio
+    pin: GPIO2
+    id: wifi_led
+  - platform: gpio
+    pin: GPIO4
+    id: ble_led
+
+light:
+  - platform: monochromatic
+    output: wifi_led
+    name: "WiFi Status LED"
+  - platform: monochromatic
+    output: ble_led
+    name: "BLE Status LED"
+
+# UART for Midea AC communication
+uart:
+  id: uart_midea
+  tx_pin: GPIO17
+  rx_pin: GPIO16
+  baud_rate: 9600
+  stop_bits: 1
+  data_bits: 8
+  parity: NONE
+
+# Midea AC Control
+climate:
+  - platform: midea
+    name: "AC Controller"
+    uart_id: uart_midea
+    autoconf: true
+    beeper: false
+    period: 2s
+    timeout: 5s
+    num_attempts: 3
+    supported_modes:
+      - COOL
+      - HEAT
+      - DRY
+      - FAN_ONLY
+    supported_swing_modes:
+      - VERTICAL
+      - HORIZONTAL
+      - BOTH
+    supported_presets:
+      - ECO
+      - BOOST
+      - SLEEP
+    visual:
+      min_temperature: 17 °C
+      max_temperature: 30 °C
+      temperature_step: 0.5 °C
+
+# Bluetooth Low Energy Beacon
+esp32_ble_beacon:
+  type: iBeacon
+  uuid: 'c29ce823-e67a-4e71-bff2-abaa32e77a98'  # Change to unique UUID
+  major: 1
+  minor: 1
+  tx_power: 0dBm
+
+# Beeper control switch
+switch:
+  - platform: template
+    name: "AC Beeper"
+    icon: "mdi:volume-source"
+    optimistic: true
+    turn_on_action:
+      - midea_ac.beeper_on:
+    turn_off_action:
+      - midea_ac.beeper_off:
+```
+
+---
+
+## Design Checklist
+
+### Schematic Design
+- [ ] ESP32-WROOM-32E module placed
+- [ ] Power supply circuit (5V → 3.3V)
+- [ ] Logic level shifter (TXB0104) connected
+- [ ] Midea AC connector (JST-XH or USB)
+- [ ] USB-to-Serial (optional but recommended)
+- [ ] Status LEDs with current limiting resistors
+- [ ] Reset and Boot buttons
+- [ ] Decoupling capacitors (10µF + 100nF per power pin)
+- [ ] Pull-up resistors for buttons
+
+### PCB Layout
+- [ ] ESP32 antenna clearance (15mm no-ground zone)
+- [ ] Power traces adequate width (0.5mm minimum)
+- [ ] Ground planes on bottom layer
+- [ ] UART traces kept short and away from power
+- [ ] Decoupling caps close to power pins
+- [ ] Thermal vias under regulator
+- [ ] Component labels and reference designators
+- [ ] Test points for debugging
+
+### Testing
+- [ ] Power supply verification (3.3V stable)
+- [ ] ESP32 boot and WiFi connection
+- [ ] UART communication test
+- [ ] Logic level shifter functionality (3.3V ↔ 5V)
+- [ ] Midea AC communication
+- [ ] BLE beacon transmission
+- [ ] OTA update capability
+
+---
+
+## Manufacturing Notes
+
+### PCB Specifications
+- **Layers**: 2-layer minimum, 4-layer recommended
+- **Thickness**: 1.6mm standard
+- **Copper Weight**: 1oz (35µm)
+- **Surface Finish**: HASL or ENIG (ENIG for better quality)
+- **Solder Mask**: Green (standard) or custom color
+- **Silkscreen**: White or black
+
+### Assembly
+- **Component Package**: 0603 or 0805 (hand-solderable)
+- **ESP32 Module**: Can be hand-soldered or reflow
+- **Level Shifter**: TSSOP-14 (requires careful soldering or stencil)
+
+### Recommended PCB Manufacturers
+- **JLCPCB**: Good for prototypes, low cost
+- **PCBWay**: Good quality, reasonable price
+- **OSHPark**: US-based, good for small batches
+
+---
+
+## Cost Estimation
+
+### PCB Only (10 pieces)
+- 2-layer 50×60mm: ~$5-10
+- 4-layer 50×60mm: ~$20-30
+
+### Components (per unit)
+- ESP32-WROOM-32E: $2-3
+- TXB0104: $0.50
+- AMS1117-3.3: $0.20
+- CP2102N: $1-2 (optional)
+- Other components: $1-2
+- **Total per unit**: ~$5-8
+
+### Total Cost (10 units)
+- PCB: $10-30
+- Components: $50-80
+- **Total**: ~$60-110 for 10 units
+
+---
+
+## Next Steps
+
+1. **Create KiCad Schematic**
+   - Add ESP32-WROOM-32E module
+   - Design power supply
+   - Add level shifter circuit
+   - Connect all components
+
+2. **Design PCB Layout**
+   - Place components
+   - Route traces
+   - Add ground planes
+   - Verify design rules
+
+3. **Order Prototype**
+   - Generate Gerber files
+   - Order PCBs (start with 5-10 pieces)
+   - Order components
+   - Assemble and test
+
+4. **Test and Iterate**
+   - Test power supply
+   - Test ESP32 functionality
+   - Test Midea communication
+   - Test BLE beacon
+   - Fix any issues
+
+---
+
+## References
+
+- [ESP32-WROOM-32E Datasheet](https://www.espressif.com/sites/default/files/documentation/esp32-wroom-32e_esp32-wroom-32ue_datasheet_en.pdf)
+- [TXB0104 Datasheet](https://www.ti.com/lit/ds/symlink/txb0104.pdf)
+- [ESPHome Midea Component](https://esphome.io/components/climate/midea/)
+- [ESPHome BLE Beacon](https://esphome.io/components/esp32_ble_beacon.html)
+- [KiCad ESP32 Footprints](https://github.com/KiCad/kicad-footprints)
+
+---
+
+**Last Updated**: December 2025  
+**Design Status**: Specification Complete - Ready for Schematic Design
+