Circuit Documentation

Summary

The circuit in question is designed to control a pair of DC motors using an L298N motor driver, interfaced with an Arduino UNO microcontroller. The system also includes an HC-SR04 ultrasonic sensor for distance measurement and an SG90 servo motor for directional control. A 12V battery provides power to the motor driver, which in turn powers the DC motors. The Arduino UNO is powered through its Vin pin connected to the battery and regulates power to the servo motor and the ultrasonic sensor. The circuit is intended for a robotic application that requires obstacle detection and navigation.

Component List

Arduino UNO

• Microcontroller board based on the ATmega328P
• Provides I/O pins for interfacing with various sensors and actuators

HC-SR04 Ultrasonic Sensor

• Measures distances by emitting ultrasonic waves and measuring the time taken for the echo to return
• Operates on 5V and provides distance measurement for obstacle detection

SG90 Servo Motor

• A small and lightweight servo motor used for precise angular movement
• Typically used for steering mechanisms in robotic applications

L298N DC Motor Driver

• An H-bridge motor driver capable of driving a pair of DC motors
• Accepts high-level signal inputs to control the speed and direction of the motors

DC Motor (x2)

• Converts electrical energy into mechanical energy to drive the robot's wheels
• Operated by the L298N motor driver

Battery 12V

• Provides the main power source for the motor driver and indirectly for the DC motors

LED: Two Pin (red)

• A simple red LED used as an indicator or for debugging purposes

Wiring Details

Arduino UNO

• 5V and GND pins provide power to the HC-SR04 ultrasonic sensor and the SG90 servo motor
• Vin receives power from the 12V battery
• Digital pins D5, D6, D7, D8, D9, and D10 are connected to the L298N motor driver for motor control
• Analog pins A1 and A2 are connected to the TRIG and ECHO pins of the HC-SR04 ultrasonic sensor, respectively
• Digital pin D13 is connected to the PWM pin of the SG90 servo motor for control

HC-SR04 Ultrasonic Sensor

• VCC connected to 5V on the Arduino UNO
• GND connected to GND on the Arduino UNO
• TRIG connected to A1 on the Arduino UNO
• ECHO connected to A2 on the Arduino UNO

SG90 Servo Motor

• PWM connected to D13 on the Arduino UNO
• 5V and GND connected to the corresponding power pins on the Arduino UNO

L298N DC Motor Driver

• 12V and GND connected to the corresponding pins on the 12V battery
• 5V connected to Vin on the Arduino UNO
• ENA, IN1, IN2, IN3, IN4, and ENB connected to digital pins D5, D7, D8, D9, D10, and D6 on the Arduino UNO, respectively
• OUT1, OUT2, OUT3, and OUT4 connected to the DC motors

DC Motors

• Each motor has two pins connected to the OUT pins of the L298N motor driver

Battery 12V

• + connected to 12V on the L298N motor driver
• - connected to GND on the L298N motor driver and the Arduino UNO

LED: Two Pin (red)

• Not explicitly wired in the provided net list

Documented Code

#include <Servo.h>  // Include the Servo library

Servo myServo;  // Create a servo object to control the servo

// Define pins for L298N motor driver
#define enA 5
#define in1 7
#define in2 8
#define in3 9
#define in4 10
#define enB 6

// Define pins for HC-SR04 ultrasonic sensor
#define echo A2
#define trigger A1

// Define the pin for the servo
#define servoPin 13

int Set = 20;  // Set distance threshold in cm
int distance_L, distance_F, distance_R;

void setup() {
  Serial.begin(9600); // Start serial communication at 9600bps

  // Set ultrasonic sensor pins as input/output
  pinMode(echo, INPUT);
  pinMode(trigger, OUTPUT);

  // Set L298N motor driver pins as output
  pinMode(enA, OUTPUT);
  pinMode(in1, OUTPUT);
  pinMode(in2, OUTPUT);
  pinMode(in3, OUTPUT);
  pinMode(in4, OUTPUT);
  pinMode(enB, OUTPUT);

  // Set speed for motors
  analogWrite(enA, 130);
  analogWrite(enB, 130);

  // Attach the servo to pin 13 and sweep it
  myServo.attach(servoPin);
  for (int angle = 70; angle <= 140; angle += 5) {
    myServo.write(angle);
    delay(100);
  }
  for (int angle = 140; angle >= 0; angle -= 5) {
    myServo.write(angle);
    delay(100);
  }
  for (int angle = 0; angle <= 70; angle += 5) {
    myServo.write(angle);
    delay(100);
  }

  // Initial ultrasonic reading
  distance_F = Ultrasonic_read();
  delay(500);
}

void loop() {
  // Obstacle avoiding logic
  distance_F = Ultrasonic_read();
  Serial.print("D F="); Serial.println(distance_F);

  // If no obstacle ahead, move forward
  if (distance_F > Set) {
    forword();
  } else {
    // Check left and right sides if obstacle is detected ahead
    Check_side();
  }

  delay(10);  // Short delay for stability
}

// Function to read the ultrasonic sensor
long Ultrasonic_read() {
  digitalWrite(trigger, LOW);
  delayMicroseconds(5);
  digitalWrite(trigger, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigger, LOW);

  long time = pulseIn(echo, HIGH, 38000); // Limit to 38ms

  if (time == 0) {
    Serial.println("No echo detected");
    return 9999; // Return large value if no echo is detected
  }

  long distance = time / 29 / 2;  // Convert time to distance in cm
  Serial.print("Distance: "); Serial.println(distance);
  return distance;
}

void compareDistance() {
  if (distance_L > distance_R) {
    turnLeft();
    delay(200);
    forword();
    delay(700);
    turnRight();
    delay(500);
  } else {
    turnRight();
    delay(300);
    forword();
    delay(700);
    turnLeft();
    delay(500);
  }
}

void Check_side() {
  Stop();  // Stop the robot before checking sides
  delay(100);

  // Move servo to check right side
  Serial.println("Checking Right");
  myServo.write(140);
  delay(300);
  distance_R = Ultrasonic_read();
  Serial.print("D R="); Serial.println(distance_R);
  delay(100);

  // Move servo to check left side
  Serial.println("Checking Left");
  myServo.write(0);
  delay(500);
  distance_L = Ultrasonic_read();
  Serial.print("D L="); Serial.println(distance_L);
  delay(100);

  // Reset servo to center
  myServo.write(70);
  delay(300);

  compareDistance();  // Compare distances and decide direction
}

void forword() {  // Move forward
  digitalWrite(in1, LOW);
  digitalWrite(in2, HIGH);
  digitalWrite(in3, HIGH);
  digitalWrite(in4, LOW);
}

void turnRight() { // Turn right
  digitalWrite(in1, LOW);
  digitalWrite(in2, HIGH);
  digitalWrite(in3, LOW);
  digitalWrite(in4, HIGH);
}

void turnLeft() {  // Turn left
  digitalWrite(in1, HIGH);
  digitalWrite(in2, LOW);
  digitalWrite(in3, HIGH);
  digitalWrite(in4, LOW);
}

void Stop() {  // Stop
  digitalWrite(in1, LOW);
  digitalWrite(in2, LOW);
  digitalWrite(in3, LOW);
  digitalWrite(in4, LOW);
}

This code controls the servo motor and the DC motors based on the distance measurements from the ultrasonic sensor. It includes functions for moving forward, turning, and stopping the robot. The servo motor is used to scan the environment by moving the ultrasonic sensor to the left and right. The robot uses this information to navigate and avoid obstacles.