What is the HC-05 Bluetooth Module?

The HC-05 module enables wireless communication between electronic devices over short distances. It uses Bluetooth technology to establish a serial communication link between a microcontroller or other embedded systems and a host device like a smartphone, tablet, or computer.

What is the HC-05 used for?

Key Features:

1. Bluetooth Version: HC-05 is typically based on Bluetooth version 2.0 + EDR (Enhanced Data Rate).

2. Serial Communication: It communicates with the host microcontroller using serial UART (Universal Asynchronous Receiver-Transmitter) communication protocol.

3. Operating Voltage: Most HC-05 modules operate at 3.3V or 5V, making them compatible with a wide range of microcontrollers and development boards.

4. Operating Range: The effective range of communication varies depending on the conditions but is typically around 10 meters (class 2).

5. Configuration Modes: The HC-05 module can operate in different modes, including AT command mode for configuration and transparent communication mode for data transfer.

6. PIN Interface: It has a set of pins for power supply, ground, serial communication (TX and RX), and mode selection (e.g., AT mode).

7. Pairing: It supports both master and slave modes, allowing it to connect to other Bluetooth devices as either the primary (master) or secondary (slave) device.

How does HC-05 control LED?

To control an LED using an Arduino Uno R3 and an HC-05 Bluetooth module, you'll need to follow these general steps:

1. Hardware Setup:
Connect the HC-05 module to the Arduino Uno R3. Typically, you'll connect the HC-05 module's TX pin to Arduino's RX pin, and the HC-05's RX pin to Arduino's TX pin. Also, ensure that the HC-05 module is powered properly (3.3V or 5V depending on the module).
Connect an LED and a current-limiting resistor to one of the digital output pins of the Arduino Uno R3. For example, connect the anode of the LED to a digital pin (e.g., pin 13) and connect the cathode through a resistor (220-330 ohms) to ground.

2. Software Setup:
Write a sketch (Arduino program) that listens for commands over the serial port and controls the LED accordingly.
Pair your HC-05 module with your Bluetooth-enabled device (e.g., smartphone or computer).

3. Bluetooth Communication:
Use a serial terminal app on your Bluetooth-enabled device to send commands (e.g., '1' to turn on the LED, '0' to turn it off) to the HC-05 module connected to the Arduino Uno R3.

4. Testing:
Upload the sketch to your Arduino Uno R3. Power up the Arduino Uno R3 and ensure that the HC-05 module is paired with your Bluetooth device.
Open the serial terminal app on your Bluetooth device and send commands to control the LED.