HC-05 Bluetooth Module for Arduino & Microcontrollers | Wireless Serial Communication Module

Description

The HC-05 Bluetooth Module is a popular and reliable wireless communication module designed for serial data transmission between microcontrollers and Bluetooth-enabled devices such as smartphones, tablets, and laptops. Based on Bluetooth Classic (v2.0 + EDR) technology, the HC-05 module supports both Master and Slave modes, making it highly flexible for a wide range of embedded and IoT applications.

This module communicates using UART (TTL serial interface), allowing seamless integration with Arduino, Raspberry Pi, STM32, ESP boards, PIC, AVR, and other development platforms. The HC-05 Bluetooth Module is widely used in robotics, home automation, wireless sensor networks, and DIY electronics projects due to its stable performance, easy configuration, and low power consumption.

Key Features of HC-05 Bluetooth Module

• Supports Bluetooth V2.0 + EDR

• Operates in Master or Slave mode

• Default baud rate: 9600 bps

• Serial communication via UART (TXD/RXD)

• On-board 3.3V logic level support

• Built-in antenna for stable wireless range

• Status LED for connection indication

• Compatible with Arduino, Raspberry Pi, STM32, ESP8266, ESP32, and more

• Simple AT command configuration

• Compact and lightweight design

Technical Specifications

Pin Configuration

The HC-05 Bluetooth Module typically comes with the following pins:

• EN / KEY – Enable AT command mode

• VCC – Power supply (3.6V–6V)

• GND – Ground

• TXD – Transmit data

• RXD – Receive data

• STATE – Connection status output

⚠️ Note: RX pin is 3.3V tolerant. Use a voltage divider when connecting to 5V microcontrollers.

Applications of HC-05 Bluetooth Module

The HC-05 Bluetooth Module is ideal for:

• Arduino Bluetooth projects

• Wireless robotics control

• Home automation systems

• Smartphone-controlled devices

• IoT and embedded systems

• Wireless data logging

• Industrial automation prototypes

• Educational & DIY electronics kits

Why Choose HC-05 Bluetooth Module?

The HC-05 Bluetooth Module offers a perfect balance of ease of use, flexibility, and reliability. Unlike BLE modules, HC-05 supports classic Bluetooth serial communication, which is ideal for continuous data transmission. Its ability to switch between Master and Slave modes makes it suitable for advanced networking projects where device-to-device communication is required.

Whether you are a student, hobbyist, educator, or professional developer, this module provides a cost-effective solution for adding wireless connectivity to your projects.

Compatibility

• Arduino UNO / Nano / Mega

• Raspberry Pi

• STM32 Boards

• ESP8266 / ESP32

• PIC & AVR microcontrollers

• USB-TTL Serial converters