Obstacle_Avoider_Car_(Sunil_Singh)

 #include <SoftwareSerial.h>

// Motor Pins

#define IN1 2

#define IN2 3

#define IN3 4

#define IN4 5

// Enable Pins for PWM Speed Control

#define ENA 9

#define ENB 8

// Ultrasonic Sensor Pins

#define TRIG 6

#define ECHO 7

// Bluetooth TX/RX

SoftwareSerial bt(10, 11); // TX, RX

char data;

int distanceThreshold = 20; // Threshold distance in cm

int motorSpeed = 100; // Speed value (0-255), reduce this to lower the speed

void setup() {

  Serial.begin(9600);

  bt.begin(9600);

  // Motor pins as output

  pinMode(IN1, OUTPUT);

  pinMode(IN2, OUTPUT);

  pinMode(IN3, OUTPUT);

  pinMode(IN4, OUTPUT);

  pinMode(ENA, OUTPUT);

  pinMode(ENB, OUTPUT);

  // Ultrasonic sensor pins

  pinMode(TRIG, OUTPUT);

  pinMode(ECHO, INPUT);

  // Initial motor states

  digitalWrite(IN1, LOW);

  digitalWrite(IN2, LOW);

  digitalWrite(IN3, LOW);

  digitalWrite(IN4, LOW);

}

void loop() {

  // Check distance using ultrasonic sensor

  int distance = getDistance();

  if (distance > 0 && distance < distanceThreshold) {

    // Obstacle detected - avoid it

    stoprobot();

    delay(500); // Brief pause before turning

    avoidObstacle();

  } else {

    // No obstacle detected - respond to Bluetooth commands

    if (bt.available()) {

      data = bt.read();

      Serial.println(data);

      switch (data) {

        case 'F':                              

          forward();

          break;

        case 'B':                

          reverse();

          break;

        case 'L':        

          left();

          break;        

        case 'R':                    

          right();

          break;

        case 'S':                                          

          stoprobot();

          break;    

      }

    }

  }

  delay(100);

}

// Movement Functions

void forward() {

  analogWrite(ENA, motorSpeed); // Set speed for left motor

  analogWrite(ENB, motorSpeed); // Set speed for right motor

  digitalWrite(IN1, HIGH);

  digitalWrite(IN2, LOW);

  digitalWrite(IN3, LOW);

  digitalWrite(IN4, HIGH);

}

void reverse() {

  analogWrite(ENA, motorSpeed);

  analogWrite(ENB, motorSpeed);

  digitalWrite(IN1, LOW);

  digitalWrite(IN2, HIGH);

  digitalWrite(IN3, HIGH);

  digitalWrite(IN4, LOW);

}

void left() {

  analogWrite(ENA, motorSpeed / 2); // Reduce speed on left motor

  analogWrite(ENB, motorSpeed);     // Full speed on right motor

  digitalWrite(IN1, HIGH);

  digitalWrite(IN2, LOW);

  digitalWrite(IN3, HIGH);

  digitalWrite(IN4, LOW);

}

void right() {

  analogWrite(ENA, motorSpeed);     // Full speed on left motor

  analogWrite(ENB, motorSpeed / 2); // Reduce speed on right motor

  digitalWrite(IN1, LOW);

  digitalWrite(IN2, HIGH);

  digitalWrite(IN3, LOW);

  digitalWrite(IN4, HIGH);

}

void stoprobot() {

  analogWrite(ENA, 0);

  analogWrite(ENB, 0);

  digitalWrite(IN1, LOW);

  digitalWrite(IN2, LOW);

  digitalWrite(IN3, LOW);

  digitalWrite(IN4, LOW);

}

// Function to avoid obstacles

void avoidObstacle() {

  reverse();    // Move backward slightly

  delay(500);

  stoprobot();  // Stop before turning

  delay(500);

 

  left();       // Rotate left to change direction

  delay(800);   // Adjust delay to fine-tune turning angle

  stoprobot();  // Stop after turn

  delay(500);

}

// Function to get the distance from the ultrasonic sensor

int getDistance() {

  digitalWrite(TRIG, LOW);

  delayMicroseconds(2);

  digitalWrite(TRIG, HIGH);

  delayMicroseconds(10);

  digitalWrite(TRIG, LOW);

  long duration = pulseIn(ECHO, HIGH);

  int distance = duration * 0.034 / 2; // Convert to cm

  return distance;

}