Components Required

• Arduino Uno (or Nano)
• HC‑05 or HC‑06 Bluetooth Module
• L298N Motor Driver Module
• 2x DC Motors + Wheels (or 4‑wheel chassis)
• Robot car chassis + battery pack (6–12V)
• Jumper wires & breadboard (optional)
• Android smartphone with Bluetooth Terminal/Control App

Tip: Many e‑commerce sites sell this as an Arduino Robot Car Kit — saves time gathering parts.

How It Works

• Your smartphone sends commands via Bluetooth (“F”=Forward, “B”=Backward, “L”=Left, “R”=Right).
• HC‑05 module receives the command and passes it to Arduino.
• Arduino runs code to interpret command → sets motor driver pins accordingly.
• The L298N then drives the motors to move the robot.

In short: Phone → Bluetooth → Arduino → Motor Driver → Motors → ROBOT MOVES!

Circuit Wiring

1. Bluetooth Module HC‑05

• VCC → 5V (Arduino)
• GND → GND
• TX → Arduino RX (pin 0)
• RX → Arduino TX (pin 1) (⚠ Use a voltage divider to drop 5V → 3.3V, since HC‑05 RX is 3.3V tolerant)

2. L298N Motor Driver

• IN1 → Arduino D8
• IN2 → Arduino D9
• IN3 → Arduino D10
• IN4 → Arduino D11
• ENA → 5V (or Arduino PWM pin for speed control)
• ENB → 5V (same as above)
• Motor A → Left motor
• Motor B → Right motor
• Motor supply (12V battery pack) → Vcc of L298N

3. Common

• Arduino GND → L298N GND → HC‑05 GND.

(Insert simple wiring diagram: Arduino + HC‑05 + L298N + Motors)

Arduino Code (Bluetooth Robot Control)

C++

char command;  // Stores received Bluetooth command

 

// Motor driver pins

int in1 = 8;

int in2 = 9;

int in3 = 10;

int in4 = 11;

 

void setup() {

Serial.begin(9600);  // Start serial for Bluetooth communication

pinMode(in1, OUTPUT);

pinMode(in2, OUTPUT);

pinMode(in3, OUTPUT);

pinMode(in4, OUTPUT);

}

 

void loop() {

if (Serial.available() > 0) {

command = Serial.read();   // Read command from phone

Serial.println(command);

 

switch(command) {

case ‘F’:  // Forward

digitalWrite(in1, HIGH);

digitalWrite(in2, LOW);

digitalWrite(in3, HIGH);

digitalWrite(in4, LOW);

break;

 

case ‘B’:  // Backward

digitalWrite(in1, LOW);

digitalWrite(in2, HIGH);

digitalWrite(in3, LOW);

digitalWrite(in4, HIGH);

break;

 

case ‘L’:  // Left

digitalWrite(in1, LOW);

digitalWrite(in2, HIGH);

digitalWrite(in3, HIGH);

digitalWrite(in4, LOW);

break;

 

case ‘R’:  // Right

digitalWrite(in1, HIGH);

digitalWrite(in2, LOW);

digitalWrite(in3, LOW);

digitalWrite(in4, HIGH);

break;

 

case ‘S’:  // Stop

digitalWrite(in1, LOW);

digitalWrite(in2, LOW);

digitalWrite(in3, LOW);

digitalWrite(in4, LOW);

break;

}

}

}

Step‑by‑Step Build Process

1. Assemble the chassis: Fix motors, wheels, and battery pack.
2. Connect components: Arduino + Bluetooth + L298N → Motors.
3. Upload Arduino code: Paste above sketch into Arduino IDE.
4. Pair Bluetooth module with phone:
   • Turn on robot → open phone Bluetooth → Pair with “HC‑05” (password often 1234 or 0000).
5. Open control app: On Android, use “Arduino Bluetooth Controller” or “Bluetooth Terminal”.
6. Send commands:
   • F → Forward
   • B → Backward
   • L → Left
   • R → Right
   • S → Stop

That’s it → Robot now obeys your smartphone commands!

Tips & Troubleshooting

• If the robot wheels move in the opposite direction → swap motor wires.
• To control speed → use analogWrite() on L298N ENA/ENB pins instead of tying them to 5V.
• Ensure common ground between Arduino, L298N, and HC‑05.
• If RX/TX pins conflict with USB → unplug HC‑05 while uploading sketch.

Advanced Upgrades

• Add Ultrasonic sensor → Robot stops when obstacle detected.
• Use custom Bluetooth controller app with directional buttons.
• Add voice commands from phone (“Forward”, “Stop”).
• Upgrade to Wi‑Fi control (ESP32/ESP8266) for long range.

FAQs

Q1: Can I use ESP32 instead of Arduino + HC‑05?
Yes: ESP32 has Bluetooth built‑in, so you don’t need an extra module.

Q2: Can I control the robot from an iPhone?
HC‑05 works with Android only (Classic Bluetooth). For iOS, use Wi‑Fi or Bluetooth Low Energy (ESP32).

Q3: Why use L298N motor driver?
Because Arduino can’t provide enough current to directly drive DC motors.

Conclusion

A Bluetooth Controlled Robot is an awesome step into robotics:

• Teaches wireless communication.
• Combines Arduino coding + motor driver circuits.
• Results in a satisfying robot you control from your phone.

Start with basic directional control, then upgrade with sensors, voice, and IoT for a real smart robot.