Port pinning
| Pin | Function | Pigtail wire color |
|---|---|---|
| 1 | GND | brown |
| 2 | TX (transmit) | white |
| 3 | RX (receive) | blue |
| 4 | VIN, 5V or 3.3V | black |
Important: Connect the TX (transmit) pin of one device to the RX (receive) pin of the other device, and vice versa. Do not connect TX to TX or RX to RX. Ensure that both devices share a common GND connection.