Initial KiCad project

Midea_ESP/2X4_HEADER_PINOUT.md

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+# 2x4 Programming Header Pinout
+
+## Header J2 - 2x4 Programming Header (8 Pins Total)
+
+This is a standard 2-row, 4-column header (2.54mm pitch) commonly used for programming headers.
+
+### Physical Layout
+
+```
+Top View:
+┌─────────────┐
+│ 1  2  3  4  │  ← Top row
+│ 5  6  7  8  │  ← Bottom row
+└─────────────┘
+```
+
+**Pin Numbering:**
+- Top row (left to right): Pins 1, 2, 3, 4
+- Bottom row (left to right): Pins 5, 6, 7, 8
+
+### Pin Assignment
+
+| Pin | Signal | ESP32 Connection | Description |
+|-----|--------|------------------|-------------|
+| **1** | **+3V3** | +3V3 Power Rail | Optional - Power ESP32 from programmer |
+| **2** | **GND** | GND | Ground reference (required) |
+| **3** | **UART_TX** | GPIO1 (UART0 TX) | ESP32 transmits to programmer |
+| **4** | **UART_RX** | GPIO3 (UART0 RX) | ESP32 receives from programmer |
+| **5** | **DTR** | GPIO0 | Data Terminal Ready (auto-reset) |
+| **6** | **RTS** | EN | Request To Send (auto-reset) |
+| **7** | **NC** | - | Not connected (spare) |
+| **8** | **NC** | - | Not connected (spare) |
+
+### Connection to USB-to-Serial Adapter
+
+| USB-to-Serial Pin | J2 Pin | Signal | Notes |
+|-------------------|--------|--------|-------|
+| VCC (3.3V) | Pin 1 | +3V3 | Optional - only if powering ESP32 from adapter |
+| GND | Pin 2 | GND | **Required** - always connect |
+| RX | Pin 3 | UART_TX | Adapter RX receives from ESP32 TX |
+| TX | Pin 4 | UART_RX | Adapter TX sends to ESP32 RX |
+| DTR | Pin 5 | DTR | Auto-reset control |
+| RTS | Pin 6 | RTS | Auto-reset control |
+| - | Pin 7 | NC | Spare (not used) |
+| - | Pin 8 | NC | Spare (not used) |
+
+**Important Notes:**
+- **RX/TX are swapped** - Adapter RX connects to ESP32 TX (Pin 3), and vice versa
+- **Do NOT connect VCC** if ESP32 is already powered from J1 (JST connector)
+- **Always connect GND** - critical for proper operation
+- **DTR and RTS** enable automatic reset (no button pressing needed)
+
+### Advantages of 2x4 Header
+
+1. **Standard layout** - Common 2.54mm pitch header format
+2. **More stable** - 2-row design is more mechanically stable
+3. **Spare pins** - Pins 7 and 8 available for future expansion
+4. **Easy to connect** - Standard programming cable format
+5. **Prevents wrong orientation** - 2-row design makes it harder to connect backwards
+
+### KiCad Symbol
+
+**Library:** `Connector_PinHeader_2.54mm`  
+**Symbol:** `PinHeader_2x04_P2.54mm_Vertical`
+
+### Optional Pull-up Resistors
+
+For maximum reliability, add pull-up resistors:
+- **R5**: 10kΩ between J2 Pin 5 (DTR) and +3V3
+- **R6**: 10kΩ between J2 Pin 6 (RTS) and +3V3
+
+Most USB-to-Serial adapters have built-in pull-ups, but adding them on the board ensures reliable operation.
+
+### Flashing Process
+
+1. Connect USB-to-Serial adapter to J2 header (pins 1-6)
+2. Power the board (via J1 JST connector or J2 Pin 1)
+3. Use `esptool` or ESPHome to flash:
+   ```bash
+   esptool.py --port /dev/ttyUSB0 write_flash 0x0 firmware.bin
+   ```
+4. DTR/RTS signals automatically put ESP32 into boot mode
+5. No button pressing required!
+
+### Future Expansion
+
+Pins 7 and 8 are spare and can be used for:
+- Additional UART (if needed)
+- I2C (SDA/SCL) for debugging
+- SPI (MISO/MOSI) for additional peripherals
+- GPIO monitoring
+- Or leave as NC (Not Connected)
+
+---
+
+## Summary
+
+**2x4 Header Layout:**
+```
+Top Row:    VCC  GND  TX   RX
+Bottom Row: DTR  RTS  NC   NC
+```
+
+**6 pins used** (1-6) for programming  
+**2 pins spare** (7-8) for future use
+
+This is a standard, stable, and convenient programming header configuration!
+
+