HC-05 Bluetooth V2.0 Breakout Board (Host/Slave, 3.6-6V)

The HC-05 breakout module is a serial Bluetooth transceiver based on the BT2.0+EDR chip. It enables simple and reliable wireless communication between your microcontroller (Arduino, ESP32, Raspberry Pi, etc.) and a terminal device (smartphone, PC) or another Bluetooth module.

Once paired, the module acts as a full-duplex serial gateway: you do not need to understand complex Bluetooth protocols. Simply send data on the TXD/RXD pins as you would with a standard USB serial cable. The module includes a 3.3V LDO regulator and a reverse polarity protection diode, accepting an input voltage between 3.6 V and 6 V.

Specifications

• Chipset: Bluetooth v2.0+EDR (Class 2)
• Supply Voltage: 3.6 V to 6 V (do not exceed 7 V)
• Current Draw: ~30 mA (unpaired) / ~10 mA (paired)
• Logic Level: 3.3 V (directly compatible with 3.3 V GPIOs)
• Baud Rates: 4,800 to 1,382,400 bps
• Effective Range: ~10 meters in open space
• Pins: VCC, GND, TXD, RXD, STATE/KEY (pin 34)
• AT Mode: Configurable via AT commands (host or slave mode, default password "1234")
• Dimensions: 35.7 mm x 15.2 mm

Note: The logic level is 3.3 V. Do not connect this module directly to an RS-232 converter (MAX232). For 5 V microcontrollers (like the standard Arduino Uno), use a voltage divider on the RX line or a series resistor to protect the HC-05 inputs.