Components

• Arduino Uno
• HC-05 Bluetooth module
• LED + resistor

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Wiring

Learn how to implement Arduino Bluetooth Control to manage LED devices effectively.

Bluetooth:

• VCC → 5V
• GND → GND
• TX → Pin 10
• RX → Pin 11

LED:

• Positive → Pin 7
• Negative → GND (through resistor)

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Code

#include <SoftwareSerial.h>SoftwareSerial BT(10, 11); // RX, TX
int led = 7;void setup() {
  pinMode(led, OUTPUT);
  BT.begin(9600);
}void loop() {
  if (BT.available()) {
    char data = BT.read();    if (data == '1') {
      digitalWrite(led, HIGH);
    }
    else if (data == '0') {
      digitalWrite(led, LOW);
    }
  }
}

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How to Use

1. Pair phone with HC-05
2. Use a Bluetooth terminal app
3. Send:
   • “1” → LED ON
   • “0” → LED OFF

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What Happens

• Phone sends data via Bluetooth
• Arduino reads it
• Controls LED instantly

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What You’ve Achieved

You now understand:

• Sensors (temperature & distance)
• Output devices (LED, buzzer)
• Communication (Bluetooth)

👉 This is the foundation of real-world IoT systems