Voice Controlled Robotic Car using Arduino, L298N Motor Driver, and HC-05 Bluetooth Module.

You will build a robotic car that responds to voice commands via a Bluetooth module (HC-05). The voice commands will be converted to text using a mobile app like “Arduino Voice Control”, then transmitted over Bluetooth to the Arduino, which will control the car’s motion.

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Components Required

Component	Quantity
Arduino UNO/Nano	1
L298N Motor Driver	1
HC-05 Bluetooth Module	1
DC Motors (Gear Motors)	2 (or 4)
Wheels	2 (or 4)
Chassis	1
Battery Pack (6V or 12V)	1
Jumper Wires	As needed

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Wiring Connections

1. L298N Motor Driver to Arduino:

L298N Pins	Arduino Pins
IN1	4
IN2	5
IN3	6
IN4	7
ENA	10 (PWM)
ENB	11 (PWM)

• Connect Motor A to OUT1 & OUT2
• Connect Motor B to OUT3 & OUT4
• Connect 12V & GND to Battery
• Connect 5V (from L298N) to Arduino 5V (if jumper is on)

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2. HC-05 Bluetooth Module to Arduino:

HC-05 Pins	Arduino Pins
VCC	5V
GND	GND
TXD	RX (Pin A0)
RXD	TX (Pin A1)

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Voice Commands Expected

You can use an Android app like “Arduino Bluetooth Control” or “BT Voice Control for Arduino”.

Commands to send via voice (converted to text over Bluetooth):

• forward
• backward
• left
• right
• stop

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Arduino Code

#include <SoftwareSerial.h>

// Motor Pins
const int IN1 = 4;
const int IN2 = 5;
const int IN3 = 6;
const int IN4 = 7;
const int ENA = 10;
const int ENB = 11;

// SoftwareSerial for Bluetooth on A0 (RX) and A1 (TX)
SoftwareSerial BTSerial(A0, A1); // RX, TX

String command = "";

void setup() {
  // Motor pins as output
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);
  pinMode(ENA, OUTPUT);
  pinMode(ENB, OUTPUT);

  // Start hardware Serial for debug output
  Serial.begin(9600);
  while (!Serial) {
    ; // Wait for Serial Monitor to open
  }
  Serial.println("Serial monitor started. Waiting for Bluetooth commands...");

  // Start SoftwareSerial for Bluetooth communication
  BTSerial.begin(9600);
}

void loop() {
  if (BTSerial.available()) {
    command = BTSerial.readStringUntil('\n');
    command.trim();  // remove whitespace and newline

    Serial.print("Command received via Bluetooth: ");
    Serial.println(command);

    if (command == "forward") {
      moveForward();
      Serial.println("Moving forward");
    } else if (command == "backward") {
      moveBackward();
      Serial.println("Moving backward");
    } else if (command == "left") {
      turnLeft();
      Serial.println("Turning left");
    } else if (command == "right") {
      turnRight();
      Serial.println("Turning right");
    } else if (command == "stop") {
      stopMotors();
      Serial.println("Stopping motors");
    } else {
      Serial.println("Unknown command");
    }
  }
}

void moveForward() {
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
  analogWrite(ENA, 200);
  analogWrite(ENB, 200);
}

void moveBackward() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, HIGH);
  analogWrite(ENA, 200);
  analogWrite(ENB, 200);
}

void turnLeft() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
  analogWrite(ENA, 180);
  analogWrite(ENB, 180);
}

void turnRight() {
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, HIGH);
  analogWrite(ENA, 180);
  analogWrite(ENB, 180);
}

void stopMotors() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, LOW);
  analogWrite(ENA, 0);
  analogWrite(ENB, 0);
}

Mobile App (Voice to Bluetooth)

You can use any of these Android apps:

• BT Voice Control for Arduino
• Arduino Bluetooth Control

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Tips & Troubleshooting

• Make sure your HC-05 baud rate is 9600.
• Disconnect HC-05 when uploading code to Arduino.
• Use a motor power source (6V–12V battery) capable of supplying enough current.
• Ensure Bluetooth is paired with your phone (default HC-05 password is usually 1234 or 0000).