HC-05 6 Pin Wireless Bluetooth RF Transceiver Module Serial Arduino Master Slave

$7.40 Inc. GST

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HC-05 Bluetooth Module: Empower Your Arduino and ESP32 Projects with Wireless Versatility

The HC-05 Bluetooth module stands as a trusted solution to enhance your Arduino and ESP32 projects with two-way (full-duplex) wireless functionality.

Seamless Communication: This module serves as a versatile bridge, enabling communication between microcontrollers like Arduino and a broad range of Bluetooth-equipped devices, including smartphones and laptops. With a plethora of readily available Android applications, this process becomes exceptionally user-friendly. The module employs USART at a 9600 baud rate, simplifying integration with any USART-supporting microcontroller.

Important Note: Keep in mind that these modules are not compatible with modern iPhones and iPads, as these devices rely on Bluetooth Low Energy (BLE) technology.

Applications Know No Bounds: Unlock the potential of the HC-05 Bluetooth module across various applications:

  • Wireless Communication: Establish seamless connections between two microcontrollers.
  • Cross-Device Connectivity: Communicate effortlessly with laptops, desktops, and mobile phones.
  • Data Logging: Craft efficient data logging applications.
  • Consumer Electronics: Elevate consumer-focused applications.
  • Robotics Unleashed: Enable wireless capabilities for robotics projects.
  • Home Automation: Simplify and enhance home automation ventures.
  • DIY Enthusiasts: Fuel your creativity with hobby projects.
  • Innovative Accessories: Design cutting-edge mobile phone accessories.

HC-05 Key Features:

  • A serial Bluetooth module tailored for Arduino and other microcontrollers.
  • Operating Voltage: Typically 4V to 6V (+5V).
  • Low Operating Current: Only 30mA.
  • Impressive Range: Up to <100m.
  • Compatibility with Serial Communication (USART) and TTL standards.
  • Adheres to the IEEE 802.15.1 standardized protocol.
  • Utilizes Frequency-Hopping Spread Spectrum (FHSS) technology.
  • Versatile Operating Modes: Master, Slave, or Master/Slave.
  • Easy Integration: Seamlessly interfaces with laptops and mobile phones via Bluetooth.
Pin Name Function
1 Key The pin state determines whether the module works in AT command mode or normal mode

[High=AT commands receiving mode(Commands

response mode), Low or NC= Bluetooth module normally working]

2 Vcc +5V Positive supply needs to be given to this pin for powering the module
3 Gnd Connect to ground
4 TXD Serial data is transmitted by module through this pin (at 9600bps by default), 3.3V logic
5 RXD Serial data is received by module through this pin (at 9600bps by default),3.3V logic
6 State The pin is connected to the LED on the board to represent the state of the module

Getting Started with HC-05 in AT Mode: Here’s a simple guide to kickstart your HC-05 in AT mode. Connect an HC-05 module to an Arduino Nano and follow these steps:

  1. Provide 3.3V to the EN (enable) pin during BT boot to enable AT commands.
  2. Maintain the EN pin high to send commands.
  3. Alternatively, use the onboard button to initiate AT mode and issue commands.

Sample Sketch:

//  Sketch: basicSerialWithNL_001


//  Uses hardware serial to talk to the host computer and software serial 

//  for communication with the Bluetooth module

//  Intended for Bluetooth devices that require line end characters “rn”


//  Pins

//  Arduino 5V out TO BT VCC 

//  Arduino 3.3V out TO BT EN (when you want to send AT commands)

//  Arduino GND to BT GND

//  Arduino D9 to BT RX through a voltage divider 

//  Arduino D8 BT TX (no need voltage divider)


//  When a command is entered in the serial monitor on the computer 

//  the Arduino will relay it to the bluetooth module and display the result.




#include <SoftwareSerial.h>

SoftwareSerial BTserial(8, 9); // RX | TX


const long baudRate = 38400; 

char c=’ ‘;

boolean NL = true;


void setup() 



    Serial.print(“Sketch:   “);   Serial.println(__FILE__);

    Serial.print(“Uploaded: “);   Serial.println(__DATE__);

    Serial.println(” “);



    Serial.print(“BTserial started at “); Serial.println(baudRate);

    Serial.println(” “);



void loop()



    // Read from the Bluetooth module and send to the Arduino Serial Monitor

    if (BTserial.available())


        c = BTserial.read();





    // Read from the Serial Monitor and send to the Bluetooth module

    if (Serial.available())


        c = Serial.read();



        // Echo the user input to the main window. The “>” character indicates the user entered text.

        if (NL) { Serial.print(“>”);  NL = false; }


        if (c==10) { NL = true; }




Once your sketch is uploaded, open the serial monitor, set the new line to “Both NL & CR,” and set the baud rate to 38400.
The HC-05 module will indicate its status through LED flashes.

You HC-05 should turn on and off every 2 seconds when in AT mode. Fast flash when ready to pair and slow flash when paired.

If you have booted the HC-05 with the button pressed or EN pin high, you should now be able to send AT commands and receive back status.

Unleash the power of wireless communication in your projects with the HC-05 Bluetooth module. Simplify complex connections and explore new possibilities in Arduino and ESP32 development.

Additional information

Weight 20 g
Dimensions 260 × 160 × 20 mm


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