How to interface HC-05 Bluetooth Module with Arduino

Use Android mobile technology to control different appliances. To control various home appliances from mobile, Bluetooth dedicated application should be installed on his/her Android phone and by using that application you can send commands. Through Bluetooth technology, we can wirelessly control appliances. Bluetooth module is used to receive those commands and this Bluetooth device is connected to Arduino. Upon particular commands, This Arduino acts as a controller and a hub that switches respective devices connected to the circuit. Hence appliances will be turned on or off depending on the command given. It is an application based Part, where u can control the electronic appliances in the home by an android application. By using this app, you can control the electronic appliance in homes within a range of Bluetooth. The block diagram of interfacing Bluetooth with Arduino is shown below. 

HC-05 Chip is known as Bluetooth SPP (Serial Port Protocol) module. It is Used for transparent wireless serially connecting setup.It is fully dedicated Bluetooth V2.0+EDR (Enhanced Data Rate) 3Mbps Modulation Along with complete 2.4GHz radio transceiver. It has CSR Blue core 04-External single chip Bluetooth system with Complementary Metal Oxide Semiconductor technology and with AFH (Adaptive Frequency Hopping Feature). It has the Dimensions as small as 12.7mmx27mm.

Experimental Setup HC-05 Pinout (Right): 

• TXD: Transmit Serial Data from HC-05 to Arduino Serial Receive.  NOTE: 3.3V HIGH level: OK for Arduino 

• KEY: If brought HIGH before power is applied, forces AT Command Setup Mode. LED blinks slowly (2 seconds) 

• VCC: +5 Power 

• GND: System / Arduino Ground 17 

• RXD: Receive Serial Data from Arduino Serial Transmit 

• STATE: Tells if connected or not


1. Connect TX (pin 11) from Arduino board to the RX pin of the module. 

2. Connect RX (pin 10) from Arduino board to the TX pin of the module. 

3. Connect 5v pin in Arduino board to the VCC pin of the module. 

4. The GND pin of the module to GND pin in Arduino board. 

5. Now open Arduino IDE(Any Version) and connect Arduino to the PC. 

6. Set the Serial Port For the Connection Arduino from Tools>>Port 

7. Upload the Program (Given) To the Board. 

8. Make Sure the Software Serial Pins of the Arduino is Correctly Initialized

Software program 

SoftwareSerial mySerial(10, 11); 

• This Command Set the Pin 10 to the Rx ok the Arduino and Tx of the Module should be connected 

• This command set the pin 11 to the Tx of the Arduino and Rx of the Module Should be connected 

• Make Sure that both the serial connections are set at same Baud Rate(For Convenience ) e.g 9600 

• Serial.begin(9600); Between Arduino and PC 

• mySerial.begin(9600); Between Arduino and Module 


• There is an increasing demand for smart homes where appliance react automatically to changing environmental conditions and can be easily controlled by a common device • The wireless technology is especially important in home where there exists hardly any infrastructure to interconnect intelligent appliances 


Bluetooth is undeniably resource which can make a home automated. People can control their electrical devices and setup desired actions through mobile.In future this product may have high potential for marketing as it is cheap and easy.

© Asad Saleh Hayat ( – Report page no 16 to 19 –Smart Home Automation

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