Project Hub /IoT & Connected Devices/Smart Home & Building Automation/Arduino Bluetooth Control Device

Beginner

ARDUINO

₹500 – ₹1,500

3 – 6 Hours

Complete Kit

Arduino Bluetooth Control Device

This project demonstrates how to control LEDs or AC appliances wirelessly using an Android smartphone, an Arduino Uno, an HC-05 Bluetooth module, and a custom app built with MIT App Inventor.

Originally published on ElectronicsForU

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

Arduino UNO R3 Board (Compatible) – ATmega328P Microcontroller with USB Cable Rs. 999.00
ESP32 WiFi+Bluetooth CP2102 Development Board Rs. 520.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
10pcs - 220 ohm 1/4 W Resistor Set Rs. 39.00
10pcs 5mm RED Diffused Light Emitting Diodes - LEDs Set Rs. 39.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

This list includes a generic resistor set as a placeholder — it is not matched to the exact value or part number this circuit needs. The correct one is specified on the original source page linked above; check it before buying.

Browse all components

How It Works

The Arduino Bluetooth Control Device system operates by establishing a wireless serial communication link between an Android smartphone and an Arduino Uno via an HC-05 Bluetooth module. The HC-05 module pairs with the smartphone, receiving serial command characters transmitted by a custom application built in MIT App Inventor. When the user interacts with the smartphone interface, the app sends specific string or byte commands through the Bluetooth airwaves. The HC-05 module captures these wireless signals and passes them to the Arduino Uno through serial communication lines, specifically utilizing a voltage divider composed of a 1-kilo-ohm resistor and a 2-kilo-ohm resistor on the receive line to safely step down logic levels from the 5V Arduino board to the 3.3V-tolerant HC-05 module. An additional 330-ohm resistor limits current to a 5mm LED acting as a visual indicator. Once the Arduino Uno processes the incoming serial byte within its programmed sketch, it evaluates the command and toggles the state of its digital output pins accordingly. This switching mechanism demonstrates the foundational architecture required for remote automation, allowing low-voltage wireless inputs to control physical hardware actions on the breadboard circuit.

Why Build This

Gain practical experience designing custom Android control interfaces using MIT App Inventor to interface with physical microcontroller hardware.

Understand wireless serial communication protocols and hardware-level logic level shifting using passive resistor dividers.

Build a foundational prototype for smart home automation systems capable of scaling to control real-world electrical appliances.

Real-World Application

Home automation for wirelessly controlling lights, fans, and other home appliances using an Android smartphone.

Skills You'll Learn

Wireless serial communication

Bluetooth module configuration

Android app development

logic level shifting

digital output control

breadboard prototyping

Safety Precautions

Ensure correct logic level shifting using a potential divider when connecting the Arduino Tx pin to the HC-05 Rx pin to protect the Bluetooth module's 3.3V logic tolerance. Exercise caution if expanding the circuit to control high-voltage AC appliances.

Technology Tags

ARDUINO

BLUETOOTH

HC-05

ANDROID

MIT APP INVENTOR

WIRELESS CONTROL

MOBILE APP

Frequently Asked Questions

Why is a voltage divider needed between the Arduino and the HC-05 module?

The Arduino Uno operates on 5V logic, while the HC-05 Bluetooth module's RX pin is only 3.3V tolerant. The potential divider steps down the voltage to protect the module from damage.

Do I need prior programming experience to build the MIT App Inventor interface?

No, MIT App Inventor uses a visual, block-based programming environment that makes building the Android control app straightforward for beginners.

Can this setup control actual household appliances directly?

The basic circuit controls a low-voltage 5mm LED. Controlling high-voltage AC appliances requires additional relay modules and strict adherence to electrical safety precautions.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

PRJ-01038