How to Use Bluetooth HC-06: Examples, Pinouts, and Specs

The Bluetooth HC-06 module is a widely-used wireless communication device that enables serial communication via Bluetooth technology. It is designed for transparent wireless serial connection setup and is often used in microcontroller projects to provide a bridge between the microcontroller and Bluetooth-enabled devices such as smartphones, laptops, and tablets.

• Wireless data transmission between two microcontrollers
• Remote control of robots or drones
• Bluetooth-enabled home automation systems
• Wireless sensor networks
• DIY electronics projects requiring Bluetooth connectivity

• Bluetooth Protocol: Bluetooth Specification v2.0+EDR
• Frequency: 2.4GHz ISM band
• Modulation: GFSK (Gaussian Frequency Shift Keying)
• Emission Power: ≤4dBm, Class 2
• Sensitivity: ≤-84dBm at 0.1% BER
• Speed: Asynchronous: 2.1Mbps(Max) / 160 kbps; Synchronous: 1Mbps/1Mbps
• Security: Authentication and encryption
• Profiles: Bluetooth Serial Port
• Power Supply: +3.3VDC 50mA
• Working Temperature: -20 ℃ to +75℃

1. Connect the VCC pin to the power supply (3.3V - 6V).
2. Connect the GND pin to the ground of the power supply.
3. Connect the TXD pin of the HC-06 to the RXD pin of the microcontroller.
4. Connect the RXD pin of the HC-06 to the TXD pin of the microcontroller.
5. If necessary, use the KEY pin to enter AT command mode for configuration.

• Ensure that the power supply voltage does not exceed 6V to avoid damaging the module.
• Use a voltage divider or a level shifter if the microcontroller operates at a voltage higher than 3.3V.
• When not in use, disconnect the power to save energy and extend the life of the module.
• Always pair the module with a device before attempting to communicate.
• For stable performance, keep the module away from sources of interference, such as Wi-Fi routers.

• Unable to Pair: Ensure the module is in pairing mode and that the device is within range.
• No Data Transmission: Check the wiring, especially the TXD and RXD connections.
• Intermittent Connection: Make sure there are no physical obstructions or sources of interference nearby.

• Reset the Module: Power cycle the HC-06 to reset its state.
• Check LED Indicator: The STATE pin can be monitored for connection status.
• Use AT Commands: Enter AT command mode to check and set the module's configuration.

• Q: Can the HC-06 module be used as a master device?
  • A: No, the HC-06 functions only as a slave device.
• Q: What is the default pairing code for the HC-06?
  • A: The default pairing code is usually "1234" or "0000".

// Example code for connecting the HC-06 Bluetooth module to an Arduino UNO

#include <SoftwareSerial.h>

SoftwareSerial bluetooth(10, 11); // RX, TX

void setup() {
  // Start the serial communication with the host computer
  Serial.begin(9600);
  while (!Serial) {
    ; // Wait for serial port to connect.
  }

  // Start communication with the Bluetooth module
  bluetooth.begin(9600);
  Serial.println("Bluetooth module is ready");
}

void loop() {
  // Check if data has been received from the Bluetooth module
  if (bluetooth.available()) {
    char received = bluetooth.read();
    Serial.print("Received: ");
    Serial.println(received);
  }

  // Check if data has been received from the serial monitor
  if (Serial.available()) {
    char sent = Serial.read();
    bluetooth.write(sent);
  }
}

Note: The SoftwareSerial library is used to create a serial connection on pins 10 and 11, which are not the default serial pins on the Arduino UNO. This allows you to communicate with the HC-06 module while still using the default serial connection for debugging and communication with the host computer.