Arduino Project for Bluetooth Controlled Car: Simple Guide

To build a Bluetooth controlled car with Arduino, connect a Bluetooth module (like HC-05) to the Arduino and control motor drivers via Bluetooth commands from a smartphone app. Use Serial communication to receive commands and control the car's movement by driving motors accordingly.

Syntax

This project uses the Serial interface to communicate with the Bluetooth module and control motors via digital pins connected to a motor driver.

• Serial.begin(9600); initializes serial communication at 9600 baud rate.
• Serial.available() checks if data is received from Bluetooth.
• Serial.read() reads the incoming command.
• Motor control pins are set as OUTPUT and controlled with digitalWrite().

arduino

void setup() {
  Serial.begin(9600); // Start serial communication
  pinMode(2, OUTPUT); // Motor A forward
  pinMode(3, OUTPUT); // Motor A backward
  pinMode(4, OUTPUT); // Motor B forward
  pinMode(5, OUTPUT); // Motor B backward
}

void loop() {
  if (Serial.available()) {
    char command = Serial.read();
    // Commands: 'F' forward, 'B' backward, 'L' left, 'R' right, 'S' stop
    switch (command) {
      case 'F':
        digitalWrite(2, HIGH);
        digitalWrite(3, LOW);
        digitalWrite(4, HIGH);
        digitalWrite(5, LOW);
        break;
      case 'B':
        digitalWrite(2, LOW);
        digitalWrite(3, HIGH);
        digitalWrite(4, LOW);
        digitalWrite(5, HIGH);
        break;
      case 'L':
        digitalWrite(2, LOW);
        digitalWrite(3, HIGH);
        digitalWrite(4, HIGH);
        digitalWrite(5, LOW);
        break;
      case 'R':
        digitalWrite(2, HIGH);
        digitalWrite(3, LOW);
        digitalWrite(4, LOW);
        digitalWrite(5, HIGH);
        break;
      case 'S':
        digitalWrite(2, LOW);
        digitalWrite(3, LOW);
        digitalWrite(4, LOW);
        digitalWrite(5, LOW);
        break;
    }
  }
}

Example

This example shows a complete Arduino sketch to control a car's motors using Bluetooth commands sent from a phone app. Commands 'F', 'B', 'L', 'R', and 'S' move the car forward, backward, left, right, and stop respectively.

arduino

void setup() {
  Serial.begin(9600); // Initialize Bluetooth serial communication
  pinMode(2, OUTPUT); // Motor A forward
  pinMode(3, OUTPUT); // Motor A backward
  pinMode(4, OUTPUT); // Motor B forward
  pinMode(5, OUTPUT); // Motor B backward
}

void loop() {
  if (Serial.available()) {
    char command = Serial.read();
    switch (command) {
      case 'F': // Forward
        digitalWrite(2, HIGH);
        digitalWrite(3, LOW);
        digitalWrite(4, HIGH);
        digitalWrite(5, LOW);
        break;
      case 'B': // Backward
        digitalWrite(2, LOW);
        digitalWrite(3, HIGH);
        digitalWrite(4, LOW);
        digitalWrite(5, HIGH);
        break;
      case 'L': // Left
        digitalWrite(2, LOW);
        digitalWrite(3, HIGH);
        digitalWrite(4, HIGH);
        digitalWrite(5, LOW);
        break;
      case 'R': // Right
        digitalWrite(2, HIGH);
        digitalWrite(3, LOW);
        digitalWrite(4, LOW);
        digitalWrite(5, HIGH);
        break;
      case 'S': // Stop
        digitalWrite(2, LOW);
        digitalWrite(3, LOW);
        digitalWrite(4, LOW);
        digitalWrite(5, LOW);
        break;
    }
  }
}

Common Pitfalls

1. Incorrect wiring: Connecting the Bluetooth module or motors incorrectly can cause the car not to respond. Always double-check connections.

2. Baud rate mismatch: The Bluetooth module and Arduino must use the same baud rate (usually 9600).

3. Missing motor driver: Motors cannot be powered directly from Arduino pins; use a motor driver like L298N.

4. Not reading serial data properly: Forgetting to check Serial.available() before reading causes errors.

arduino

/* Wrong way: Reading serial without checking availability */
void loop() {
  char command = Serial.read(); // May read nothing or garbage
  // ...
}

/* Right way: */
void loop() {
  if (Serial.available()) {
    char command = Serial.read();
    // ...
  }
}

Quick Reference

• HC-05 Bluetooth Module: Connect VCC to 5V, GND to GND, TX to Arduino RX (pin 0), RX to Arduino TX (pin 1) via voltage divider.
• Motor Driver Pins: Connect motor driver inputs to Arduino pins 2, 3, 4, 5.
• Commands: 'F' = forward, 'B' = backward, 'L' = left, 'R' = right, 'S' = stop.
• Serial Baud Rate: 9600 for communication.

Key Takeaways

Use Serial communication to receive Bluetooth commands and control motors.

Always check Serial.available() before reading data to avoid errors.

Use a motor driver to safely power motors from Arduino.

Match baud rates between Arduino and Bluetooth module for proper communication.

Test wiring carefully to ensure correct connections for Bluetooth and motors.