Home Automation Using HC-05 BT Module

Introduction: Home Automation Using HC-05 BT Module

About: I am an undergraduate student pursuing B.Tech in EEE(Electrical and Electronics Engineering).I am passionate about creating new stuffs using technology and hungry to learn more and more.

Using Home Automation one can remotely control any number of devices through a smartphone.

In this project we will be building an Home Automation system using HC-05 BT module with arduino and control the devices through an app developed using MIT app inventor.

You can recreate this project to automate devices in your room !!

The video is provided in the last step.

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Step 1: Components Required

You will need the following components

>Arduino Uno R3

>LED ( Red x1 , Blue x2 )


>Jumper wires

>Two Pin plug ( x2 )

>Bulb ( x1 )

>BT HC-05 module

>2 channel relay

>Power Distribution Board

>Smartrphone with an app installed to control the devices

>2 resistors with value of one resistor double than the other

Step 2: Build Voltage Divider for BT HC-05 Module

Since RX & TX operate on 3.3V logic

We need a voltage division of 3.3v for the connection TX of arduino -> RX of module

We have used two resistors of values 10k and 20k.

We have Vin=5V

According to calculations Vout=20k/(20k+10k) *5V so Vout =3.3V.

Step 3: Connecting BT Module With Arduino

Make the following connection:

Bluetooth Module Pin => Arduino Pin

TX => RX

RX => TX



Make sure you have colorwise arrangement as in the image (To avoid confusion at a late stage)

Step 4: Connecting Relay With Arduino

We make use of a Relay(an electromagnetic switch)which provides isolation between the high (the BULB) and low (the ARDUINO) voltage circuit.

Make the circuit connections as follows

>COM terminal (relay) => Supply from mains

> NO terminal (relay) => Supply line to bulb

>VCC (relay) => 5V ( arduino )

>GND (relay) => GND ( arduino )

>IN1 (relay) => D8 ( arduino )

>IN2 (relay) => D9 ( arduino )

Step 5: Connect the Devices

Since we are using a two channel relay we will be controlling two bulbs as our devices.

-connecting supply from mains to COM terminal on relay board.

and supply to the device to NO terminal on relay board.

Step 6: Add LED for Indication

This is not an compulsory step and is only meant as 'fail-safe' step meant to prevent blowing up of devices!

Before connecting the high voltage devices connect two LED which can be used for test purpose .

Red LED ( indicating device 1) => Digital pin 6

Blue LED ( indicating device 2) => Digital pin 11

Step 7: Upload Sketch

Download the attached arduino sketch and upload it using arduino IDE.

If you don't have an IDE, download from https://www.arduino.cc/en/Main/Software

Step 8: Build Your Own Customised App

I made use of the MIT app inventor to design my own simple application to control 2 devices through my Smartphone.

Here is the link to learn about making an app for yourself

I am also attaching an apk file of my application designed for this project.

Step 9: Control Devices Using Your Smartphone

-Open up your Smartphone

-Start your device bluetooth.

-Run the app designed for Home Automation.

-Pair up with the HC-05 BT module.

-Control desired devices.

Step 10: Watch Tutorial

I hope that you found this instructable useful.

The demonstrative video is also attached here.

Automate your room now !!

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    2 Discussions


    2 years ago

    Is there any need for Voltage divider if I use NodeMCU?? Because NodeMCU gives 3.3v in the digital pins


    2 years ago

    This looks real fun. I'll connect devices such as my laptop to turn them on and use remotely although there might be better ways to do it which I don't know about.