Bluetooth-Controlled Car with Arduino and HC-05 Module

What is a Bluetooth Controlled Car?

A Bluetooth controlled car is a wireless robotic vehicle that can be operated remotely using a smartphone or tablet via Bluetooth communication.

This innovative robotics project allows students to control the car's movements—forward, backward, left, and right—through a simple mobile application, eliminating the need for physical remote controls or wired connections. 

Components Required 

To build this exciting DIY project, you'll need the following components: 

• Arduino Uno: The brain of the project - a microcontroller that processes commands 
• HC-05 Bluetooth Module: Creates wireless communication between your phone and Arduino 
• DC Motors (2): Provide power to move the wheels and propel the car 
• L298N Motor Driver: Safely manages high current needed by motors based on Arduino signals 
• Wheel Caster Set (2): Ensures proper steering and maneuverability 
• Chassis: The base structure that holds all components together 
• Power Source: Rechargeable batteries (Li-ion recommended) for mobile operation 
• Jumper Wires: Connect all electronic components 
• Breadboard (Optional): Useful for circuit prototyping 
• Buzzer: Adds audio feedback for enhanced user experience 
• Smartphone: With Bluetooth capability to control the car 

Circuit Connections and Wiring 

Here's the detailed step-by-step connection guide for your Bluetooth controlled car project: 

Main Components Layout 

The diagram illustrates the complete circuit architecture with the L298N Motor H-Bridge as the central control unit, connecting the Arduino microcontroller to the DC gear motors and servo motors. 

Arduino to L298N Motor Driver Connections: 

• Digital Pin 12 → IN1 (Motor A control) 
• Digital Pin 11 → IN2 (Motor A control) 
• Digital Pin 10 → IN3 (Motor B control) 
• Digital Pin 9 → IN4 (Motor B control) 
• 5V Pin → VCC (Logic power supply) 
• GND Pin → Ground (Common ground) 

L298N Motor Driver to DC Gear Motors: 

• Left DC Gear Motor → Motor A terminals (OUT1 and OUT2) 
• Right DC Gear Motor → Motor B terminals (OUT3 and OUT4) 
• Motor Power Supply → 12V input terminal on L298N 

Power Supply Connections: 

• Battery Pack (7.4V Li-ion recommended) connects to: 
• Positive terminal → VIN on Arduino and motor power input on L298N 
• Negative terminal → Common ground for entire circuit 

HC-05 Bluetooth Module Connections: 

• VCC → Arduino 5V pin 
• GND → Arduino Ground pin 
• TX → Arduino Digital Pin 2 (Software Serial RX) 
• RX → Arduino Digital Pin 3 (Software Serial TX) 

Additional Servo Motor Integration: 

As shown in the diagram, if you're adding servo motors for enhanced functionality: 

• DC Servo Motor → Connect to Arduino PWM pins (Pin 5 and Pin 6) 
• Power lines → 5V and Ground from Arduino 

Wire Color Coding (As Per Diagram) 

Following the standard color coding shown in the circuit diagram: 

• Red wires: Positive power connections (+5V, +12V) 
• Black wires: Ground/negative connections 
• Green wires: Digital signal lines to motor driver 
• Blue wires: Bluetooth module data connections 
• Orange/Yellow wires: Motor control signals

Arduino Code 

Here's the complete code for your Bluetooth controlled car:

#include  
 
// Define motor control pins 
#define IN1 12 
#define IN2 11 
#define IN3 10 
#define IN4 9 
 
// Create SoftwareSerial object for Bluetooth communication 
SoftwareSerial bluetooth(2, 3); // RX, TX 
 
char command; 
 
void setup() { 
  // Initialize serial communication 
  Serial.begin(9600); 
  bluetooth.begin(9600); 
   
  // Set motor pins as outputs 
  pinMode(IN1, OUTPUT); 
  pinMode(IN2, OUTPUT); 
  pinMode(IN3, OUTPUT); 
  pinMode(IN4, OUTPUT); 
   
  // Initialize all motors to stop 
  stopMotors(); 
   
  Serial.println("Bluetooth Car Ready!"); 
} 
 
void loop() { 
  // Check if data is available from Bluetooth 
  if (bluetooth.available()) { 
    command = bluetooth.read(); 
    Serial.println(command); 
     
    // Execute commands based on received data 
    switch(command) { 
      case '1': // Forward 
        moveForward(); 
        break; 
      case '2': // Backward 
        moveBackward(); 
        break; 
      case '3': // Left 
        turnLeft(); 
        break; 
      case '4': // Right 
        turnRight(); 
        break; 
      case '5': // Stop 
        stopMotors(); 
        break; 
      default: 
        stopMotors(); 
        break; 
    } 
  } 
} 
 
void moveForward() { 
  digitalWrite(IN1, HIGH); 
  digitalWrite(IN2, LOW); 
  digitalWrite(IN3, HIGH); 
  digitalWrite(IN4, LOW); 
} 
 
void moveBackward() { 
  digitalWrite(IN1, LOW); 
  digitalWrite(IN2, HIGH); 
  digitalWrite(IN3, LOW); 
  digitalWrite(IN4, HIGH); 
} 
 
void turnLeft() { 
  digitalWrite(IN1, LOW); 
  digitalWrite(IN2, HIGH); 
  digitalWrite(IN3, HIGH); 
  digitalWrite(IN4, LOW); 
} 
 
void turnRight() { 
  digitalWrite(IN1, HIGH); 
  digitalWrite(IN2, LOW); 
  digitalWrite(IN3, LOW); 
  digitalWrite(IN4, HIGH); 
} 
 
void stopMotors() { 
  digitalWrite(IN1, LOW); 
  digitalWrite(IN2, LOW); 
  digitalWrite(IN3, LOW); 
  digitalWrite(IN4, LOW); 
}

The Working Process

The following 5 steps describes the core working mechanism: 

• Command Transmission: When you press a directional button in the smartphone app, specific data is transmitted via Bluetooth 
• Data Reception: The HC-05 module receives this data and forwards it to the Arduino 
• Signal Processing: Arduino processes the received command using a switch-case structure 
• Motor Control: Based on the command, Arduino sends appropriate signals to the L298N motor driver 
• Movement Execution: The motor driver controls the DC motors to achieve the desired movement 

Command Mapping: 

• Forward → '1' 
• Backward → '2' 
• Left → '3' 
• Right → '4' 
• Stop → '5'