# 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