HC-05 4-Pin Bluetooth Module (Master/Slave) w/ Button
HC-05 4-Pin Bluetooth Module (Master/Slave) w/ Button - Image 2
HC-05 4-Pin Bluetooth Module (Master/Slave) w/ Button - Image 3
HC-05 4-Pin Bluetooth Module (Master/Slave) w/ Button - Image 4
SKU: IOWC-0176
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HC-05 4-Pin Bluetooth Module (Master/Slave) w/ Button

₹789.00 (Inclusive of all taxes)
Out of Stock

The HC-05 is a classic Bluetooth 2.0+EDR serial module with master/slave role switching, ideal for adding wireless UART communication to Arduino, STM32, and other microcontroller projects via AT commands.

Features

  • Classic Bluetooth V2.0+EDR Serial Module with configurable Master/Slave roles via onboard button and AT commands.
  • Simple UART (TXD/RXD) interface for direct serial communication with 3.3V/5V microcontrollers like Arduino, ESP32, or STM32.
  • Compact 4-pin design (VCC, GND, TXD, RXD) with integrated status LED and mode-switching button for easy configuration.
  • Robust RF performance with +4dBm transmit power and -84dBm receiver sensitivity for reliable links up to 10 meters in open space.
  • Default 9600 baud data mode (configurable up to 2.1Mbps) and 38400 baud command mode for flexible project integration.

Out of stock

Description

The HC-05 Bluetooth module is a foundational wireless serial bridge for embedded systems, implementing the Bluetooth V2.0+EDR specification with enhanced data rate support. It operates on the global 2.4GHz ISM band using GFSK modulation, providing a stable, point-to-point serial link replacement. Its integrated CSR core chip handles the full Bluetooth protocol stack, freeing the host microcontroller from complex RF management.

This module distinguishes itself with dual-role functionality, configurable as either a master device initiating connections or a slave device awaiting pairing. The onboard tactile button and AT command set over a dedicated 38400 baud serial channel allow for on-the-fly role switching, Bluetooth name changes, PIN modification, and baud rate adjustment. With a typical operating current of 30mA during active communication and a compact footprint, it is suited for battery-powered or space-constrained wireless data logging, remote control, and telemetry applications.

Key Features

  • Dual-Role Bluetooth 2.0+EDR Module: Functions as both Master (initiates connections) and Slave (accepts connections), switchable via AT commands or hardware button.
  • Simple Serial Port Profile (SPP): Creates a transparent wireless serial cable, seamlessly replacing wired UART connections with minimal code changes.
  • Configurable Communication Parameters: User-adjustable baud rate (up to 2.1Mbps), device name, pairing PIN, and role via industry-standard AT command set.
  • Robust RF Link: Features Class 2 (+4dBm) transmit power and -84dBm receiver sensitivity for a stable connection range of approximately 10 meters in open areas.
  • Wide Compatibility: Interfaces directly with 3.3V or 5V logic microcontrollers (Arduino, Raspberry Pi, STM32, ESP8266) using only VCC, GND, TX, and RX pins.
  • Integrated Status & Control: Onboard LED provides clear link and data transmission status; tactile button enables easy entry into AT command mode without disconnecting.

Applications

  • Wireless Serial Bridges for Arduino, Raspberry Pi, and other microcontroller projects.
  • DIY Remote Control Systems for robots, drones, and smart home actuators.
  • Wireless Data Logging and Telemetry from sensors to a PC or mobile device.
  • Bluetooth-Enabled Industrial HMIs for configuring and monitoring machinery.
  • Educational Kits for teaching embedded systems and wireless communication principles.

Technical Specifications

Bluetooth ProtocolBluetooth Specification v2.0+EDR
Frequency Range2.4GHz ISM Band
RF Transmit Power+4dBm (Class 2)
Receiver Sensitivity-84dBm at 0.1% BER
ModulationGFSK (Gaussian Frequency Shift Keying)
Data InterfaceUART (TXD, RXD)
Default Data Baud Rate9600 (8, N, 1)
Command Mode Baud Rate38400 (8, N, 1)
Supply Voltage3.3V - 5V DC
Operating Current~30 mA (pairing/active), ~8 mA (connected)
Operating Temperature-20°C to +75°C
Dimensions (L x W x H)43mm x 16.5mm x 7mm

Frequently Asked Questions

How do I switch the HC-05 module between Master and Slave modes?

To switch modes, ensure the module is powered on but not paired. Press and hold the onboard button, then power cycle the module. The LED will blink at a slower rate (approx. 2 seconds on/off) indicating entry into AT command mode. Connect the module's TXD/RXD to a USB-UART adapter, open a serial terminal at 38400 baud (8N1), and send 'AT+ROLE=1' for Master or 'AT+ROLE=0' for Slave. Remember to save with 'AT+SAVE' and reset the module for changes to take effect.

What is the correct wiring to connect the HC-05 to an Arduino Uno?

Connect the HC-05's VCC pin to the Arduino's 5V pin (or 3.3V for 3.3V logic boards), and GND to GND. For serial communication, connect the HC-05's TXD pin to the Arduino's RX pin (Digital Pin 0) and the HC-05's RXD pin to the Arduino's TX pin (Digital Pin 1). It is recommended to use a voltage divider (e.g., two resistors) on the line from Arduino TX to HC-05 RXD if using a 5V Arduino, as the HC-05's logic input is 3.3V tolerant but not 5V tolerant. Always double-check connections before powering on.

How can I change the default baud rate and Bluetooth name of my HC-05 module?

Enter AT command mode by holding the button while powering on until the LED blinks slowly. Using a serial terminal at 38400 baud, send 'AT+UART=115200,0,0' to change the data baud rate to 115200 (format: baud,stop bits,parity). Change the device name with 'AT+NAME=MyDevice'. Modify the PIN with 'AT+PSWD=4321'. After each change, send 'AT+SAVE' to store settings in non-volatile memory, then power cycle the module. The new settings will be active after reboot.

What is the typical operating range and how can I improve it?

The HC-05's Class 2 radio provides a typical open-space range of up to 10 meters. To improve range, ensure a clear line of sight between devices and minimize interference from other 2.4GHz sources like Wi-Fi routers or microwaves. You can solder a wire antenna (approx. 31mm for 2.4GHz) to the designated antenna pad on the PCB or connect an external 2.4GHz antenna via a compatible connector if your module variant has one. Using a higher-gain external antenna can significantly extend the operational distance.

Package Includes

  • 1 x HC-05 4-Pin Bluetooth Module (Master/Slave) with Button

Additional Information

Weight 0.005 kg
Dimensions 4.3 × 1.65 × 0.7 cm

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