HC-05 Wireless Bluetooth Module

The HC-05 is a Bluetooth to serial module that replaces the cable between your microcontroller and a phone, laptop, or another Bluetooth device with a transparent wireless link. Built on Bluetooth V2.0+EDR and the Serial Port Profile, it provides full-duplex communication over a simple UART connection using just four wires.

Unlike slave-only modules, it can be set as master or slave through AT commands, so it can wait for your phone to connect or actively pair with another module, perfect for robot control, home automation, and wireless data logging. The KEY pin opens AT command mode to change the name, PIN, role, and baud rate, while the STATE pin and status LED show connection status.

Out of the box it appears as “HC-05”, pairs with PIN 1234, and runs at 9600 baud, making it a dependable choice for students, makers, and Arduino enthusiasts. Its integrated antenna and compact breakout board make it easy to fit into tight enclosures and breadboard prototypes.

Specification:

• Bluetooth Version : V2.0+EDR
• Profile : Serial Port Profile (SPP)
• Chipset : CSR BlueCore 04-External
• Frequency : 2.4GHz ISM Band
• Transmit Power : Up to +4dBm
• Receiver Sensitivity : -80dBm (Typical)
• Operating Voltage : 3.3V to 5V
• Logic Level : 3.3V
• Interface : UART
• Default Baud Rate : 9600 bps
• Default PIN : 1234
• Roles : Master / Slave
• Range : Up to 10m
• Pins : VCC, GND, TXD, RXD, KEY, STATE