The HC-06 is a compact Bluetooth 2.0 module designed for simple serial communication. Unlike the HC-05, it operates only in slave mode, making it ideal for wireless data exchange between microcontrollers and Bluetooth-enabled devices like PCs and smartphones.

Specifications

• Bluetooth Version: 2.0 + EDR (Class 2)
• Frequency: 2.4 GHz ISM band
• Modulation: GFSK
• Operating Voltage: 3.6 V–6 V (typ. 5 V)
• Logic Level: 3.3 V (compatible with 5 V via voltage divider)
• Default Baud Rate: 9600 (configurable via AT commands)
• Communication Interface: UART (TX, RX)
• Role: Slave only (cannot initiate connections)
• Range: ~10 m (open space)
• LED Indicator:
  - Blinking = waiting for connection
  - Steady = connected
• Dimensions: ~37 mm × 15 mm
• Antenna: Onboard PCB antenna
• Breakout Pins:
  - VCC, GND
  - TXD, RXD
  - EN (key pin for AT mode)

Features

• Simple and reliable wireless serial communication
• Slave-only mode for pairing with master devices (e.g., PC, phone, HC-05)
• Compatible with Arduino, ESP32, STM32, and Raspberry Pi
• Ideal for wireless data logging, control, and monitoring
• Common use cases:
  - Bluetooth-controlled Arduino projects
  - Wireless sensor data transmission
  - Serial bridges and automation systems
  - DIY robotics and remote control setups