How To Control Your Bulb Using Android Devices

Control Your Bulb Using Android Devices

This project is about how one can connect an electric bulb (or any device) with an Arduino Uno using a Relay Module. It also covers connecting Arduino with Android devices and then remotely switching the device off/on.

In recent years, the term “smart homes” has gained a lot of traction. Many people attempted to offer their own version of smart house design, however, the majority of them lacked smart home device integration. In smart home architecture, security is also a key problem. Bluetooth, GSM, Zigbee, and other communications technologies are employed by these smart home architectures. Each of these architectures has its own set of advantages and disadvantages. In my last year of engineering, I attempted to create an integrated smart home architecture that could be monitored and managed using a simple user-friendly smartphone application. In addition, all of the systems will be linked, and voice commands will be added to operate gadgets within a certain range.

Components and supplies

Ph a000066 iso (1) ztbmubhmho
Arduino UNO
× 1
09590 01
LED (generic)
× 1
Mfr 25fbf52 221r sml
Resistor 221 ohm
× 1
1434509556 android phone color
Android device
× 1
61pby065esl sx679 tnr8syww5d
HC-05 Bluetooth Module
× 1

Apps and online services

LED Controller
Ide web
Arduino IDE

About this project

Watch how does it Work?

Let’s Start Building

The circuit is so simple and small, there are only a few connections to be made

Arduino Pins Bluetooth Pins

RX (Pin 0) ———-> TX

TX (Pin 1) ———-> RX

5V ———-> VCC

GND ———-> GND

Connect a LED negative to GND of Arduino and positive to pin 13 with a resistance valued between 220Ω – 1KΩ. And you’re done with the circuit

Note: Don’t  Connect RX to RX and TX to TX of Bluetooth to Arduino you will receive no data, Here TX means Transmit and RX means Receive

What Is the Process?

HC 05/06 is a serial communication device.
When a specific button is hit, the Android app is programmed to send serial data to the Bluetooth module. The data is received by the Bluetooth module and sent to Arduino through the TX pin of the Bluetooth module (RX pin of Arduino). The Arduino code compares and verifies the data it receives. When received data is 1, the LED goes on, and when received data is 0, the LED turns off.

Open the serial monitor and watch the received data.


Android Application


I will not cover android app development lessons in this course. You can get the Android application as well as the complete project’s source code here. Or you can visit  MIT App Inventor if you do not know about android app development.

How to use the App?

Watch in video how to pair to Bluetooth module

  • Download the Application form here or here
  • Pair your device with HC 05/06 Bluetooth module1) Turn ON HC 05/06 Bluetooth module2) Scan for available device3) Pair to HC 05/06 by entering default password 1234 OR 0000
  • Install  LED application on your android device
  • Open the Application
  • Press paired devices
  • Select your Bluetooth module from the List (HC 05)
  • After connecting successfully
  • Press ON button to turn ON LED and OFF button to turn OFF the LED
  • Disconnect button to disconnect from Bluetooth module

This is a very basic tutorial on how to connect a Bluetooth module to an Arduino. This project may be improved to a higher level, such as smartphone-controlled robots, home automation, and so on.



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