How to Connect a Bluetooth Module (HC-05) to Arduino — Control an LED from Your Phone

# 🔵 Control an LED with Bluetooth HC-05 & Arduino UNO | 3D Animated Tutorial 🚀 Learn how to connect an **HC-05 Bluetooth module to an Arduino UNO** and control an LED wirelessly using your smartphone! In this beginner-friendly 3D animated tutorial, you’ll learn the complete circuit wiring, voltage divider connections, Arduino programming, Bluetooth pairing, and troubleshooting. 🎬 **VIDEO TIMESTAMPS** ⏱️ 0:00 – Introduction & Project Demo ⏱️ 0:09 – Components Required ⏱️ 0:26 – Understanding the HC-05 Module ⏱️ 0:41 – Complete Wiring Guide ⏱️ 1:42 – Arduino Code Explained ⏱️ 2:10 – Pair Your Phone & Test ⏱️ 2:36 – Troubleshooting & Outro 🛠️ **COMPONENTS REQUIRED** - Arduino UNO - HC-05 Bluetooth module - Half-size breadboard - 1 kΩ resistor - 2 kΩ resistor - LED - 220 Ω resistor - Jumper wires - Android smartphone with a compatible Bluetooth serial terminal app 🔌 **CIRCUIT WIRING** 1. Arduino 5V → HC-05 VCC 2. Arduino GND → HC-05 GND 3. HC-05 TXD → Arduino D2 4. Arduino D3 → 1 kΩ resistor → HC-05 RXD 5. HC-05 RXD → 2 kΩ resistor → GND 6. Arduino D8 → 220 Ω resistor → LED positive (+) 7. LED negative (−) → GND ⚠️ **Important:** The HC-05 RXD pin typically requires 3.3V logic. Use the voltage divider to reduce the Arduino's 5V TX signal. Verify your module's pin labels and specifications before connecting it. 💻 **ARDUINO CODE — BLUETOOTH LED CONTROL** Copy this code into the Arduino IDE and upload it to your Arduino UNO. ```cpp #include SoftwareSerial.h SoftwareSerial bt(2, 3); // RX, TX const int LED_PIN = 8; void setup() { pinMode(LED_PIN, OUTPUT); bt.begin(9600); } void loop() { if (bt.available()) { char c = bt.read(); if (c == '1') { digitalWrite(LED_PIN, HIGH); bt.println("LED ON"); } else if (c == '0') { digitalWrite(LED_PIN, LOW); bt.println("LED OFF"); } } } ``` 📱 **HOW TO TEST THE PROJECT** 1. Upload the code to your Arduino UNO. 2. Power the Arduino and HC-05 module. 3. Open your phone's Bluetooth settings and pair with HC-05. 4. If prompted, try PIN `0000` or `1234`, depending on the module. 5. Open a compatible Bluetooth serial terminal app and connect to HC-05. 6. Set the serial communication to 9600 baud if the app provides that option. 7. Send `1` to turn the LED ON. 8. Send `0` to turn the LED OFF. The Arduino will send `LED ON` or `LED OFF` as a confirmation message. 🔧 **TROUBLESHOOTING** ✅ Check that TX connects to RX and RX connects to TX. ✅ Confirm the HC-05 baud rate is 9600. ✅ Verify the voltage divider connections. ✅ Check the LED polarity and resistor wiring. ✅ Make sure the phone app connects using Bluetooth Classic serial communication. 📌 **Compatibility note:** Standard HC-05 modules generally work with Android phones. iPhones typically cannot connect to them using ordinary Bluetooth serial terminal apps because of Bluetooth Classic SPP limitations. 🎯 **WHAT YOU WILL LEARN** - Arduino UNO programming - HC-05 Bluetooth communication - UART serial communication - Voltage divider circuits - Wireless LED control - Beginner electronics and IoT projects 📺 **ABOUT SENSORSTACK-EASY** Welcome to **SensorStack-Easy**, where we make Arduino, sensors, electronics, robotics, embedded systems, IoT, and AI technology easy to understand through practical projects and engaging 3D animated tutorials. 👍 Like this video if it helped you! 💬 Comment your questions below. 🔔 Subscribe to SensorStack-Easy for more exciting electronics projects. #Arduino #HC05 #ArduinoUNO #BluetoothArduino #ArduinoProjects #LEDControl #Electronics #IoT #Robotics #SensorStackEasy