HC-05 Bluetooth Module

The HC-05 Bluetooth Module provides wireless serial communication between microcontrollers, smartphones, and computers. Using Bluetooth 2.0 + EDR technology in the 2.4GHz ISM band, it communicates through a UART serial interface. The module supports both Master and Slave modes, configurable through AT commands, making it suitable for different wireless communication applications. It is commonly used in Arduino projects, phone-controlled robots, wireless sensor monitoring, and home automation systems. The typical default baud rate is 9600 bps in data mode, and its communication range is approximately 10 meters in open space. The common breakout-board version accepts 3.6V–6V power, but its RX/TX logic operates at 3.3V. Use appropriate level shifting when connecting a 5V microcontroller TX pin to the module's RX pin.