Arduino with Bluetooth Module HC-05 Connection

When you think about wireless communication a name Bluetooth must come in your mind. there are lots of wireless communication and we use all in transferring data from one point to another point. And here we are working in embedded and robotics. we are controlling things via mobile phone in embedded system and robotics with the help of Bluetooth, and Wi-fi.

Today, we are going to learn Arduino with Bluetooth Module HC-05 Connection.  It is very simple Just you need to connect four wire between Arduino and Bluetooth Module HC-05. HC-05 is most widely used Bluetooth module in the embedded and Robotics. in this article we are going to tell Arduino Uno Bluetooth interfacing. the connection will be the same for Arduino Uno and Arduino Nano. You can easily connect Bluetooth device with the Arduino. just you need to do serial communication between both devices.

Arduino with Bluetooth Module HC-05 Connection

To start with both device just look at the features of these devices

1. Bluetooth Module HC-05

Bluetooth module Hc-05 is most widely used Bluetooth module nowadays in the embedded and robotics. It can easily connect with any Bluetooth device. by default, it works as a slave. and we can change its configuration through the AT command. It has two configuration master and slave. we can use it’s both modes. it depends upon the work or projects which we have to make. Arduino Bluetooth interfacing includes UART communication. in which the data store in a parallel change in the serially through the shift register, let us suppose we have an 8-bit data in 8 lines and all data transmitted simultaneously. in that case, we require 8 wires to transmit that data. But in serial communication, we need only one wire to transmit the data. Uart arranges the data in serially with the help of Shift register.

arduino bluetooth

Before the start tutorial Bluetooth Arduino. first, we need to look at some hardware and software features of Bluetooth:-

Hardware Features

  • sensitivity nearly ‐80dBm.
  • it can work Up to +4dBm RF transmit power.
  • input voltage 3.3 to 5 V I/O.
  • PIO(Programmable Input/Output) control.
  • UART interface with customizable baud rate.
  • With an integrated antenna.
  • With the edge connector.

Software Features

  • Slave default Baud rate: 9600, Data bits:8, Stop bit:1,Parity:No parity.
  • having Auto‐connect function. .
  • Permit pairing device to connect as default..
  • Auto‐pairing PINCODE: ”1234″ and “0000”.
PIN Description of Bluetooth Module HC-05

Bluetooth module HC-05 having 6 pins and one Key at the module.

  1. Rx:-   It is used to Receive the data (UART serial port receive data).
  2. Tx:-   It is used to Transmit the data (UART serial port receive data).
  3. RST:- To reset the Module .
  4. NC:- It refers to no connections.
  5. Vcc:- At Vcc, we give power supply of 5v.
  6. GND:- Ground connection.
  7. Key:- It use for AT mode.

Circuit Diagram for Arduino with Bluetooth Module HC-05 Connection

Circuit Diagram for Arduino with Bluetooth Module
As you can see in the circuit diagram we need only four wires to interface Arduino with Bluetooth module HC-05 and the data start to transmit and receive after some command from the Arduino Uno. Arduino works on the UART communication for this configuration. To transmit the data we first enable the Serial communication in both devices by giving some command in the code.
We receive the data from the Bluetooth. We can use this data in our any application like Bluetooth control home automation and we can make a Bluetooth RC car. In this tutorial we will see the receive data in Serial monitor in Arduino IDE.
Arduino Bluetooth Module Source code for Serial monitor
void setup() {
  // put your setup code here, to run once:
void loop() {
  // put your main code here, to run repeatedly:
  int Value =;
upload this code into your Arduino IDE.
Download Bluetooth Terminal Android Software on your phone.
Connect your phone Bluetooth with Bluetooth module with “1234” Password.
Now open Serial Monitor in Arduino IDE.
Send some data from bluetooth terminal app which will show on Serial monitor.

2 thoughts on “Arduino with Bluetooth Module HC-05 Connection

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