Building a Bluetooth-Controlled Car with Arduino and HC-05 Module

This tutorial guides you through creating a Bluetooth-controlled car using an Arduino Uno and an HC-05 Bluetooth module. Inspired by Ameya Angadi's project, this car can be controlled wirelessly via a smartphone, making it a fun and educational robotics project. Original project

Components Needed

• Arduino Uno
• HC-05 Bluetooth Module
• L298N Motor Driver
• 4 DC Motors with Wheels
• Chassis for the Car
• Jumper Wires
• Breadboard
• 9V Battery (or 12V power source for motors)
• USB Cable for Arduino
• Smartphone with Bluetooth RC Controller App (e.g., from Google Play Store)

Step 1: Setting Up the Hardware

1. Assemble the Car Chassis:
   • Attach the four DC motors with wheels to the chassis corners.
   • Secure the Arduino Uno and breadboard to the chassis.
2. Connect the L298N Motor Driver:
   • Connect Motor A (left motors) to OUT1 and OUT2 on the L298N.
   • Connect Motor B (right motors) to OUT3 and OUT4 on the L298N.
   • Connect IN1 to Arduino Pin 13, IN2 to Pin 12, IN3 to Pin 11, IN4 to Pin 10.
   • Connect L298N VCC to 9V/12V battery, GND to Arduino GND and battery GND.
3. Connect the HC-05 Bluetooth Module:
   • VCC to Arduino 5V
   • GND to Arduino GND
   • TX to Arduino Pin 3 (RX, via SoftwareSerial)
   • RX to Arduino Pin 2 (TX, via voltage divider to step down 5V to 3.3V)
4. Secure all connections and ensure the battery is connected to power the motors and Arduino.

Note: Connect the HC-05 module after uploading the code to avoid errors.

Step 2: Arduino Code

The Arduino code receives commands from a smartphone via the HC-05 Bluetooth module and controls the DC motors using the L298N driver. Install the SoftwareSerial library in the Arduino IDE.

#include 

// Define pins for motor driver
#define LEFT_MOTOR_FORWARD 13
#define LEFT_MOTOR_REVERSE 12
#define RIGHT_MOTOR_FORWARD 11
#define RIGHT_MOTOR_REVERSE 10

// Define pins for Bluetooth module
#define BT_RX 3
#define BT_TX 2

SoftwareSerial bluetooth(BT_RX, BT_TX); // RX, TX

char command;

void setup() {
  // Set motor pins as outputs
  pinMode(LEFT_MOTOR_FORWARD, OUTPUT);
  pinMode(LEFT_MOTOR_REVERSE, OUTPUT);
  pinMode(RIGHT_MOTOR_FORWARD, OUTPUT);
  pinMode(RIGHT_MOTOR_REVERSE, OUTPUT);
  
  // Initialize serial communications
  Serial.begin(9600);
  bluetooth.begin(9600);
  
  // Ensure motors are off initially
  digitalWrite(LEFT_MOTOR_FORWARD, LOW);
  digitalWrite(LEFT_MOTOR_REVERSE, LOW);
  digitalWrite(RIGHT_MOTOR_FORWARD, LOW);
  digitalWrite(RIGHT_MOTOR_REVERSE, LOW);
}

void loop() {
  if (bluetooth.available()) {
    command = bluetooth.read();
    Serial.println(command); // For debugging
    
    // Stop the car
    if (command == 'S') {
      digitalWrite(LEFT_MOTOR_FORWARD, LOW);
      digitalWrite(LEFT_MOTOR_REVERSE, LOW);
      digitalWrite(RIGHT_MOTOR_FORWARD, LOW);
      digitalWrite(RIGHT_MOTOR_REVERSE, LOW);
    }
    // Move forward
    else if (command == 'F') {
      digitalWrite(LEFT_MOTOR_FORWARD, HIGH);
      digitalWrite(LEFT_MOTOR_REVERSE, LOW);
      digitalWrite(RIGHT_MOTOR_FORWARD, HIGH);
      digitalWrite(RIGHT_MOTOR_REVERSE, LOW);
    }
    // Move backward
    else if (command == 'B') {
      digitalWrite(LEFT_MOTOR_FORWARD, LOW);
      digitalWrite(LEFT_MOTOR_REVERSE, HIGH);
      digitalWrite(RIGHT_MOTOR_FORWARD, LOW);
      digitalWrite(RIGHT_MOTOR_REVERSE, HIGH);
    }
    // Turn left
    else if (command == 'L') {
      digitalWrite(LEFT_MOTOR_FORWARD, LOW);
      digitalWrite(LEFT_MOTOR_REVERSE, HIGH);
      digitalWrite(RIGHT_MOTOR_FORWARD, HIGH);
      digitalWrite(RIGHT_MOTOR_REVERSE, LOW);
    }
    // Turn right
    else if (command == 'R') {
      digitalWrite(LEFT_MOTOR_FORWARD, HIGH);
      digitalWrite(LEFT_MOTOR_REVERSE, LOW);
      digitalWrite(RIGHT_MOTOR_FORWARD, LOW);
      digitalWrite(RIGHT_MOTOR_REVERSE, HIGH);
    }
  }
}

Upload this code to your Arduino Uno using the Arduino IDE. Ensure the HC-05 is disconnected during upload to avoid errors.

Step 3: Using the Bluetooth-Controlled Car

Once the code is uploaded and the hardware is connected, you can control the car using a smartphone:

• Install a Bluetooth RC App: Download an app like "Bluetooth RC Controller" from the Google Play Store.
[](https://github.com/DevelopedByAnurag/arduino-bluetooth-car)
• Pair the HC-05: In your smartphone's Bluetooth settings, pair with the HC-05 module (default PIN is usually 1234 or 0000).
• Control the Car: Use the app to send commands:
  • 'F': Move forward
  • 'B': Move backward
  • 'L': Turn left
  • 'R': Turn right
  • 'S': Stop
• Place the car on a flat surface and test its movement in an open area.

Ensure the HC-05 is within 10 meters of the smartphone for reliable Bluetooth communication.

Step 4: Testing and Troubleshooting

1. Upload the code and open the Serial Monitor (9600 baud) to verify Bluetooth commands are received.
2. Test the motors by directly powering the L298N to ensure they work independently.
3. Check Bluetooth connectivity by pairing with the HC-05 and sending commands via the app.
4. If the car doesnt move, verify all connections, ensure the battery is sufficiently charged, and check that the HC-05 RX pin receives a 3.3V signal (use a voltage divider if needed).
5. Ensure the Bluetooth module is disconnected during code upload to prevent errors.