HC-05 AT Mode & Normal Mode Controller using Arduino

Project Overview

In this project, I created a system that allows the HC-05 Bluetooth module to switch between AT Mode and Normal Mode using an Arduino.

Normally, entering AT mode on HC-05 requires manual wiring and powering the module while holding the EN pin HIGH.But in this project, Arduino automatically controls the VCC and EN pins, making it easy to switch modes directly from the Serial Monitor.

This makes testing and configuring the Bluetooth module much easier.Main Idea of the Code

The Arduino controls two important pins of the HC-05 module:

EN pin → Used to enable AT ModeVCC pin → Used to power ON/OFF the module

Using Serial Monitor commands, the user can choose the mode.

Mode Selection

Command

Mode

A Enter AT Mode

N Enter Normal ModeAT Mode Features

When AT Mode is enabled:

HC-05 starts at 38400 baudPredefined AT commands can be executedCustom AT commands can also be sentExample commands:

Input

Command Sent

1 AT

2 AT+VERSION?

3 AT+NAME?

4 AT+ROLE?

5 AT+UART?

6 AT+PSWD?

7 AT+STATE?

Normal Mode Features

In Normal Mode:

Bluetooth runs at 9600 baudMobile phone can connect to the moduleCommands can control an LED connected to ArduinoCommands can control an LED connected to Arduino

Bluetooth Commands

Command

Action

ON LED ON

OFF LED OFF

Why This Project is Useful

This project helps beginners:

Learn HC-05 AT commandsConfigure Bluetooth modules easilyUnderstand Serial communicationControl devices via BluetoothProject Demonstration Video Link :https://youtube.com/shorts/L1YBCGEQqDY?si=EJqo2hNdHnDlCPJb