The HC-06 Bluetooth Module is a compact and efficient wireless serial communication module based on the CSR BlueCore 04-External single-chip Bluetooth system. It is a Class 2 Bluetooth device, providing a maximum transmit power of 4dBm and a range of approximately 10 meters in open-air environments.

Features:

• Slave Mode Only: Supports only slave mode operation, making it perfect for receiving data from master devices.
• Easy Integration: Communicates with microcontrollers like Arduino via the UART protocol with a default baud rate of 9600 bps (adjustable using AT commands).
• Wide Voltage Compatibility: Operates on 3.3V to 5V, allowing direct connection to various development boards.
• Compact Pinout: Minimal pins ensure easy setup and space-efficient integration.

Pinout and Connections:

Getting Started with Arduino:

1. Hardware Setup:

   • Connect the module's pins to the Arduino as described in the table above.
   • Ensure a common ground between the module and the Arduino.

2. Software Configuration:

   • Open the Arduino IDE.
   • Use the Serial Monitor to communicate with the module via AT commands for configuration.
3.  

4. Example Command:

   • To change the baud rate, send the AT command:

     AT+BAUD8

This application demonstrates how to use the HC-06 Bluetooth module to wirelessly control an LED connected to an Arduino board.

Requirements:

• Arduino board (e.g., Uno, Mega, Nano)
• HC-06 Bluetooth module
• 1 LED
• 1 Resistor (220 ohms)
• Breadboard and jumper wires
• Smartphone with a Bluetooth terminal app

Hardware Setup:

1. Connect HC-06 Module to Arduino:

   • VCC → Arduino 5V
   • GND → Arduino GND
   • TXD → Arduino RX (pin 0)
   • RXD → Arduino TX (pin 1)

2. Connect the LED to Arduino:

   • Connect the LED's anode (long leg) to pin 13 through a 220-ohm resistor.
   • Connect the cathode (short leg) to Arduino GND.

Arduino Code:

char command; // Variable to store the received command

void setup() {
  // Initialize serial communication with the Bluetooth module
  Serial.begin(9600);

  // Configure pin 13 as an output
  pinMode(13, OUTPUT);

  // Indicate ready state
  digitalWrite(13, LOW);
}

void loop() {
  // Check if data is available to read
  if (Serial.available()) {
    command = Serial.read(); // Read the command

    // Control the LED based on the received command
    if (command == '1') {
      digitalWrite(13, HIGH); // Turn LED ON
      Serial.println("LED is ON");
    } else if (command == '0') {
      digitalWrite(13, LOW); // Turn LED OFF
      Serial.println("LED is OFF");
    } else {
      Serial.println("Invalid Command. Send '1' to turn ON, '0' to turn OFF.");
    }
  }
}

How It Works:

1. Pairing the HC-06 Module:

   • Power on the HC-06 module.
   • Search for Bluetooth devices on your smartphone.
   • Pair with the module (default PIN: 1234 or 0000).

2. Using a Bluetooth Terminal App:

   • Download a Bluetooth terminal app (e.g., "Serial Bluetooth Terminal" for Android or iOS).
   • Connect to the HC-06 module through the app.

3. Testing the Application:

   • Send the command '1' via the terminal app to turn the LED ON.
   • Send the command '0' to turn the LED OFF.
   • Observe the LED and the response messages in the app.

Enhancements and Modifications:

• Multiple LEDs: Control multiple LEDs with additional commands.
• Sensors: Transmit sensor data (e.g., temperature, light) via Bluetooth.
• Motor Control: Replace the LED with a motor driver for Bluetooth-controlled robots.

This simple project demonstrates the fundamentals of using the HC-06 module with Arduino for wireless communication.