What You’ll Need (Components List)

• Arduino Uno (or ESP32/ESP8266 NodeMCU)
• L298N Motor Driver Module (to control DC motors)
• 2 or 4 DC Motors + Wheels
• Robot Chassis + battery holder
• IR Line Sensors (for line following)
• Ultrasonic Sensor HC‑SR04 + servo (for obstacle avoidance)
• Bluetooth Module (HC‑05/HC‑06) or use ESP Wi‑Fi instead
• Jumper wires, breadboard, screws

Pro tip: Buy a “Arduino Smart Car Kit” → It usually includes chassis, motors, motor driver, IR sensor, and ultrasound module.

Step 1: Assemble the Car Chassis

• Mount motors on the chassis → attach wheels.
• Fit caster wheel (for balance).
• Fix battery pack + motor driver module.
• Attach Arduino/ESP board on top with standoffs/tape.

Step 2: Wire the Components

Motor Driver (L298N) Connections

• IN1 → Arduino D8
• IN2 → Arduino D9
• IN3 → Arduino D10
• IN4 → Arduino D11
• Motors → OUT1/OUT2 (Left), OUT3/OUT4 (Right)
• ENA/ENB → 5V (or PWM pins for speed control)
• Motor Supply → 7V–12V battery

Sensor Connections

• Ultrasonic: Trig → D6, Echo → D7
• IR Line Sensors: OUT pins → Arduino D2 & D3

Bluetooth (Optional)

• HC‑05 TX → Arduino RX (D0)
• HC‑05 RX → Arduino TX (D1) (⚠ add voltage divider for 3.3V)
• VCC → 5V, GND → GND

Step 3: Arduino Code Examples

(A) Basic Forward/Backward Movement

C++

int in1=8, in2=9, in3=10, in4=11;

 

void setup() {

pinMode(in1,OUTPUT); pinMode(in2,OUTPUT);

pinMode(in3,OUTPUT); pinMode(in4,OUTPUT);

}

 

void loop() {

// Forward

digitalWrite(in1,HIGH); digitalWrite(in2,LOW);

digitalWrite(in3,HIGH); digitalWrite(in4,LOW);

delay(2000);

 

// Backward

digitalWrite(in1,LOW); digitalWrite(in2,HIGH);

digitalWrite(in3,LOW); digitalWrite(in4,HIGH);

delay(2000);

}

(B) Obstacle Avoidance Logic

C++

#define trig 6

#define echo 7

int in1=8,in2=9,in3=10,in4=11;

long duration; int distance;

 

void setup(){

pinMode(in1,OUTPUT); pinMode(in2,OUTPUT);

pinMode(in3,OUTPUT); pinMode(in4,OUTPUT);

pinMode(trig,OUTPUT); pinMode(echo,INPUT);

Serial.begin(9600);

}

 

int getDistance(){

digitalWrite(trig,LOW); delayMicroseconds(2);

digitalWrite(trig,HIGH); delayMicroseconds(10);

digitalWrite(trig,LOW);

duration=pulseIn(echo,HIGH);

return (duration*0.034/2);

}

 

void forward(){ digitalWrite(in1,HIGH); digitalWrite(in2,LOW);

digitalWrite(in3,HIGH); digitalWrite(in4,LOW);}

void stopBot(){ digitalWrite(in1,LOW); digitalWrite(in2,LOW);

digitalWrite(in3,LOW); digitalWrite(in4,LOW);}

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 loop(){

int d = getDistance();

if(d > 15) forward();

else { stopBot(); delay(500); left(); delay(700); }

}

(C) Bluetooth Controlled Smart Car (using HC‑05)

• Use Arduino Serial to read commands “F”=Forward, “B”=Backward, “L”=Left, “R”=Right, “S”=Stop.
• Then map commands to motor functions.

(We already gave this code in the Bluetooth Robot post ).

(D) ESP Upgrade – Web‑Controlled IoT Car

If using ESP8266/ESP32, you can skip Bluetooth and directly make a Web Server Car:

• Connect ESP → Wi‑Fi.
• Host UI with buttons “Forward / Back / Left / Right / Stop”.
• When tapped → ESP sets GPIO pins for motor driver.

This makes your car controllable by any phone on home Wi‑Fi (or IoT cloud for remote control).

Step 4: Test the Robot

• Upload Arduino sketch.
• Place robot on smooth, flat surface.
• Switch battery ON → Robot drives forward by default → Stops/turns if obstacle detected.
• If Bluetooth module is attached → test with smartphone control commands.

Advanced Upgrades

• Add Line Follower IR sensors → Multi‑mode smart car.
• Add Camera (ESP32‑CAM or Pi Camera) → FPV surveillance smart car.
• Add Cloud Integration → Send sensor data (temperature, distance) to Google Sheets or Thingspeak.
• Add Voice Control → Connect to Google Assistant/Alexa via ESP32.

FAQs

Q1: Arduino or ESP – which is better for Smart Car?

• Arduino Uno → Beginner friendly, simple projects (line follower, obstacle avoidance).
• ESP32/ESP8266 → For smart IoT: Wi‑Fi control, cloud integration, app dashboard.

Q2: Can I control ESP Smart Car through the internet (outside home Wi‑Fi)?
Yes — by using port forwarding, Blynk IoT, or MQTT brokers.

Q3: How many sensors can I add?
As many as GPIOs + power budget allow. Start with 2 IR and 1 ultrasonic.

Conclusion

A DIY Smart Car with Arduino/ESP is one of the best beginner robotics projects:

• Build a moving robot
• Teach it to avoid obstacles, follow lines, or obey phone commands
• Upgrade it with IoT features using ESP Wi‑Fi

For beginners → Start with Arduino Uno.
For IoT learners → Go for ESP32/ESP8266 to unlock wireless smart robotics.

The only limit is your creativity — today it’s a car, tomorrow it’s a self‑driving robot.