Initial KiCad project

Midea_ESP/AC_CONNECTION.md

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+# AC Connection Guide
+
+## JST-XH Connector on PCB (J1)
+
+The PCB includes a **JST-XH 4-pin connector (J1)** for connecting to your AC unit.
+
+### Connector Specifications
+
+- **Type:** JST-XH (2.5mm pitch)
+- **Pins:** 4-pin
+- **Part Number:** JST-XH-B4B-XH-A (female connector on PCB)
+- **Library:** `Connector_JST:JST_XH_B4B-XH-A`
+
+### Pinout (J1 on PCB)
+
+| Pin | Signal | Description |
+|-----|--------|-------------|
+| 1 | +5V | **Power input for PCB** - Powers the entire board |
+| 2 | AC_RX | Receive line from AC (5V logic) |
+| 3 | AC_TX | Transmit line to AC (5V logic) |
+| 4 | GND | Ground reference |
+
+### Connection Method
+
+1. **On PCB:** J1 connector is mounted on the PCB
+2. **Cable:** Use a cable with JST-XH connector on one end
+3. **AC Unit:** Connect the other end of the cable to your AC unit's communication port
+
+### Cable Assembly
+
+You'll need to create or purchase a cable with:
+- **One end:** JST-XH male connector (matches J1 on PCB)
+- **Other end:** Connector that matches your AC unit's port
+
+**Typical cable:**
+- JST-XH connector → AC unit's communication port
+- 4 wires: +5V (optional), AC_RX, AC_TX, GND
+
+### Wiring Notes
+
+- **+5V (Pin 1)** is the **power input for the PCB** - This powers the entire board (ESP32, regulator, etc.)
+- **AC_RX** and **AC_TX** are 5V logic levels (shifted from 3.3V by TXB0104PWR)
+- **GND** must be connected for proper communication and power
+- Ensure proper wire gauge for power delivery (recommend 22AWG or larger for +5V and GND)
+- The AC unit or external power supply must provide 5V DC to Pin 1
+
+### Safety
+
+- Ensure AC unit is powered off when connecting/disconnecting
+- Verify pinout matches your AC unit's requirements
+- Double-check GND connection before powering on
+