The HC-06 is a Bluetooth 2.0 SPP slave-only module for wireless UART communication. Simpler to use than the HC-05 (slave only, no mode switching), it pairs with a master device like a smartphone or computer.
| Pin | Name | Function | Type |
|---|---|---|---|
| 1 | RXD | UART receive | BUS |
| 2 | TXD | UART transmit | BUS |
| 3 | GND | Ground | GND |
| 4 | VCC | Power 3.6V–6V | PWR |