Arduino Bluetooth Module HC-05

Wiring Connections

• VCC: Connect to 5V on Arduino (if using 3.3V, ensure correct voltage regulation).
• GND: Connect to Ground (GND) on Arduino.
• TX (Transmit): Connect to Arduino RX (Receive) pin.
• RX (Receive): Connect to Arduino TX (Transmit) pin.
• KEY (Optional): For entering AT command mode (usually connected to 3.3V to activate AT mode).

Power

• Voltage Requirements:
  • Operates between 3.3V to 5V.
  • Typical usage is 5V for compatibility with most Arduino boards.
• Current Requirements:
  • Approximately 30mA during active communication.

Input and Output

• Inputs:
  • Receives serial data from Bluetooth-connected devices.
• Outputs:
  • Sends serial data to connected Bluetooth devices.
  • Provides status information through LED indicators (often onboard).

Physical Characteristics

• Size: Typically around 30mm x 15mm.
• Mounting: Generally comes with pins or headers for easy integration with breadboards or custom circuits.
• Connectors: Uses standard pin headers for connections.

Technical Specifications

• Bluetooth Version: 2.0+EDR (Enhanced Data Rate)
• Serial Communication: UART interface, typically at 9600 bps, but can be configured up to 115200 bps.
• Distance: Effective communication range up to 10 meters (33 feet) in open space.
• LED Indicators: Often includes LEDs to indicate power status and Bluetooth connection status.

Additional Features

• AT Command Mode: Allows for configuration and customization of Bluetooth settings through AT commands.
• Serial Communication: Makes it easy to interface with Arduino and other microcontrollers for wireless data transfer.
• Multiple Pairings: Can be paired with multiple Bluetooth devices, though only one connection can be active at a time.
• Low Power Consumption: Designed to operate efficiently with minimal power usage.

How to Use

• Connecting the Module:

• • Wiring: Connect the HC-05 module to the Arduino using the provided pins: VCC to 5V, GND to Ground, TX to RX, and RX to TX.
  • Optional: Connect the KEY pin to 3.3V if you need to enter AT command mode.

• Programming:

• • Upload Code: Write and upload code to the Arduino to handle Bluetooth communication.
  • Serial Communication: Use Serial.begin() to set up the baud rate in the Arduino code and Serial.print() or Serial.read() for sending and receiving data.

• Pairing the Module:

• • Power On: Ensure the module is powered on and within range of the Bluetooth device you want to pair with.
  • Pair: Search for the HC-05 in your Bluetooth settings on your smartphone or computer. The default pairing code is usually 1234 or 0000.

• Using AT Commands:

• • Enter AT Mode: Set the KEY pin to 3.3V and reset the module to enter AT command mode.
  • Send Commands: Use a serial terminal to send AT commands to configure settings such as device name, baud rate, and pairing codes.

• Testing:

• • Connect: After pairing, use a Bluetooth terminal app on your smartphone to connect to the HC-05.
  • Communicate: Send and receive data to verify that the module is working correctly and data is transmitted as expected.

The HC-05 Bluetooth module is a versatile and user-friendly device for adding Bluetooth capabilities to Arduino projects, providing an easy way to wirelessly communicate with other Bluetooth-enabled devices.