Bluetooth-Controlled 2-Wheel Arduino Car

Let’s build your Bluetooth-controlled 2-wheel Arduino car using a caster wheel for front balance.
Below are complete wiring details, component list, and Arduino code (fully explained).

Components Required

Component	Quantity	Description
Arduino UNO	1	Main microcontroller
L298N / HW-130 Motor Driver	1	To drive two DC motors
HC-05 Bluetooth Module	1	To receive commands from phone
DC Motors (with wheels)	2	For rear wheel drive
Caster wheel	1	For front balance
Battery (7.4V–12V)	1	Power source
Jumper wires	—	Connections

---

Wiring Connections

Motor Driver L298N

L298N Pin	Connects To	Description
IN1	Arduino pin 4	Motor A control 1
IN2	Arduino pin 5	Motor A control 2
IN3	Arduino pin 6	Motor B control 1
IN4	Arduino pin 7	Motor B control 2
ENA	Arduino pin 10 (PWM)	Speed control for left motor
ENB	Arduino pin 11 (PWM)	Speed control for right motor
OUT1, OUT2	Left motor terminals	Motor A output
OUT3, OUT4	Right motor terminals	Motor B output
+12V	Battery +	Power input
GND	Battery – & Arduino GND	Common ground
5V	Arduino 5V	To power Arduino

---

Bluetooth Module (HC-05)

HC-05 Pin	Connects To	Description
VCC	5V on Arduino	Power
GND	GND	Common ground
TX	Arduino A1 (Software RX)	Bluetooth TX → Arduino RX
RX	Arduino A0 (Software TX)	Bluetooth RX → Arduino TX (Use voltage divider if needed)

---

Android App

Use any Bluetooth Controller App (e.g., “Bluetooth RC Controller” or “Arduino Bluetooth Controller” from Play Store).
Assign these characters for movement:

• ‘F’ → Forward
• ‘B’ → Backward
• ‘L’ → Left
• ‘R’ → Right
• ‘S’ → Stop

---

Arduino Code

Upload this to your Arduino UNO:

#include <SoftwareSerial.h>

SoftwareSerial BT(A1, A0); // RX | TX

#define ENA 10
#define ENB 11
#define IN1 4
#define IN2 5
#define IN3 6
#define IN4 7

char command;

void setup() {
  Serial.begin(9600);
  BT.begin(9600);

  pinMode(ENA, OUTPUT);
  pinMode(ENB, OUTPUT);
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);

  analogWrite(ENA, 200);  // Set initial motor speed (0–255)
  analogWrite(ENB, 200);

  Serial.println("Bluetooth Car Ready. Waiting for commands...");
}

void loop() {
  if (BT.available()) {
    command = BT.read();
    Serial.println(command);

    switch (command) {
      case 'F': forward(); break;
      case 'B': backward(); break;
      case 'L': left(); break;
      case 'R': right(); break;
      case 'S': stopCar(); break;
      default: stopCar(); break;
    }
  }
}

void forward() {
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}

void backward() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, HIGH);
}

void left() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}

void right() {
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, HIGH);
}

void stopCar() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, LOW);
}

Powering Tips

• If using 9V battery, ensure it can supply enough current (better use Li-ion 18650 pack).
• Connect battery + to motor driver +12V and Arduino VIN if using same battery.
• Always share common GND between Arduino, motor driver, and Bluetooth module.

---

Working Summary

1. Pair your phone with HC-05 (default password: 1234 or 0000).
2. Open the app and connect to HC-05.
3. Press control buttons → car moves accordingly:
   • F → both wheels forward
   • B → both wheels reverse
   • L → left motor stops, right runs → turn left
   • R → right motor stops, left runs → turn right
   • S → all motors stop