Bluetooth Module with Arduino Basics

Bluetooth Module with Arduino

• The Bluetooth module with Arduino is a basic circuit set of integrated Bluetooth functions.
• It can be used for wireless network transmission and real-time data logging, or for controlling projects.
• The HC-05 is an example of a Bluetooth module.

Objectives

• Define Bluetooth module
• Configure the electrical circuit of the Bluetooth module with Arduino
• Program the Bluetooth module
• Use the Bluetooth module with Arduino to control an LED

Supported Bluetooth Devices

• Bluetooth speaker
• Bluetooth headphones
• Bluetooth mouse and keyboard
• Smartphone and tablet
• Printer
• PC
• Notebook

What is Bluetooth?

• The name Bluetooth comes from King Harald "Bluetooth" Gormsson, who lived over a thousand years ago.
• He was known for uniting Denmark and Norway (in 958).
• His dead tooth's dark blue/grey color gave him the nickname.
• In 1996, Intel, Ericsson, and Nokia collaborated to standardize Bluetooth, a short-range radio technology for supporting connectivity between products.
• The name "Bluetooth" was originally a placeholder to be used until a better name could be found, as suggested by Jim Kardach of Intel.

What is HC-05?

• HC-05 is a Bluetooth-to-Serial-Bridge module for wireless communications.
• It is used to connect two microcontrollers or a microcontroller to a smartphone, laptop, or desktop PC.
• It has a nominal range of 10 meters.
• It is easy to configure and use.

Modes of Operation

• AT Mode:
  • Uses AT commands to change HC-05 settings.
  • Configure name, baud rate, PIN code, and data rate.
• Data Mode:
  • Exchanging data between devices.
  • HC-05 acts as a transparent data gateway.

Connection Roles

• Slave Role:
  • HC-05 waits for other devices to initiate a connection.
  • Used in projects where you want to control things with a smartphone.
• Master Role:
  • HC-05 actively searches and initiates Bluetooth connections with other devices.
  • Used in microcontroller communication.

HC-05 Parts

• Power:
  • The HC-05 chip operates on 3.3V.
  • The module includes a 3.3V linear regulator for voltage between 3.6V and 6V.
• Status LED:
  • When powered, the LED flashes rapidly (about 2Hz) in pairing mode.
  • Paired: Flashes twice, pauses, repeats.
  • AT Mode: Blinks slowly and steadily.
• AT Button :
  • It is used to enter configuration mode.
• Pinout:
  • GND: Common ground pin.
  • VCC: Positive supply voltage (3.6V to 6V).
  • EN: Enables the on-board regulator.
  • RX: Receives data from the microcontroller.
  • TX: Sends data to the microcontroller.

Procedure

1. Connect the HC-05 to an Arduino or micro-controller.
2. Install a Bluetooth terminal app on your smartphone, e.g. "Serial Bluetooth Terminal."
3. Use the Software Serial library to connect the HC-05's RX and TX to the Arduino's pins.
4. Connect the HC-05 TXD to Arduino's D3
5. Connect the HC-05 RXD to Arduino's D2
6. Add a 1K resistor between HC-05 Rx and Arduino's D2, and add a 2K resistor between HC-05 Rx and GND.

Connecting to Android Phone

• Ensure the HC-05 is powered and ready to connect.
• Enable Bluetooth on your smartphone.
• Touch and Hold the bluetooth icon on your phone and select "Pair new device"
• Select your HC-05 name from the list of available devices.
• Enter the PIN code (1234 is typical).
• Use the Bluetooth Serial Terminal app for further communication, if needed. Install if necessary.

Output

• The initial message from the Arduino via the Bluetooth serial module and code.

Coding

• Example code to initialize the Serial and Bluetooth communication.