Circuit Documentation

Summary

This document describes an obstacle avoidance robot circuit. The circuit includes an Arduino UNO microcontroller, two DC motors, a servo motor, an ultrasonic sensor, a motor driver, and a battery pack. The robot moves forward until an obstacle is detected. When an obstacle is detected, the robot stops, the servo rotates to scan for a clear path, and the robot turns in the direction of the clear path.

Component List

1. Arduino UNO

   • Description: Microcontroller board based on the ATmega328P.
   • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

2. DC Motor (Motor 1)

   • Description: Standard DC motor.
   • Pins: pin 1, pin 2

3. DC Motor (Motor 2)

   • Description: Standard DC motor.
   • Pins: pin 1, pin 2

4. 3xAAA Battery Pack with Switch and JST

   • Description: Battery pack providing power to the circuit.
   • Pins: POS, NEG

5. Servo

   • Description: Servo motor for rotating to scan for obstacles.
   • Pins: gnd, vcc, pulse

6. HC-SR04 Ultrasonic Sensor

   • Description: Ultrasonic sensor for detecting obstacles.
   • Pins: VCC, TRIG, ECHO, GND

7. L298N DC Motor Driver

   • Description: Motor driver for controlling the DC motors.
   • Pins: OUT1, OUT2, 12V, GND, 5V, OUT3, OUT4, 5V-ENA-JMP-I, 5V-ENA-JMP-O, +5V-J1, +5V-J2, ENA, IN1, IN2, IN3, IN4, ENB

Wiring Details

Arduino UNO

• 5V: Connected to VCC of Servo and VCC of HC-SR04 Ultrasonic Sensor.
• GND: Connected to GND of Servo, GND of HC-SR04 Ultrasonic Sensor, GND of L298N DC Motor Driver, and NEG of 3xAAA Battery Pack.
• Vin: Connected to POS of 3xAAA Battery Pack.
• D11: Connected to ENA of L298N DC Motor Driver.
• D10: Connected to IN1 of L298N DC Motor Driver.
• D9: Connected to IN2 of L298N DC Motor Driver.
• D8: Connected to IN3 of L298N DC Motor Driver.
• D7: Connected to IN4 of L298N DC Motor Driver.
• D6: Connected to ENB of L298N DC Motor Driver.
• D5: Connected to pulse of Servo.
• D3: Connected to ECHO of HC-SR04 Ultrasonic Sensor.
• D2: Connected to TRIG of HC-SR04 Ultrasonic Sensor.

DC Motor (Motor 1)

• pin 1: Connected to OUT4 of L298N DC Motor Driver.
• pin 2: Connected to OUT3 of L298N DC Motor Driver.

DC Motor (Motor 2)

• pin 1: Connected to OUT2 of L298N DC Motor Driver.
• pin 2: Connected to OUT1 of L298N DC Motor Driver.

3xAAA Battery Pack with Switch and JST

• POS: Connected to 12V of L298N DC Motor Driver and Vin of Arduino UNO.
• NEG: Connected to GND of L298N DC Motor Driver and GND of Arduino UNO.

Servo

• vcc: Connected to 5V of Arduino UNO.
• gnd: Connected to GND of Arduino UNO.
• pulse: Connected to D5 of Arduino UNO.

HC-SR04 Ultrasonic Sensor

• VCC: Connected to 5V of Arduino UNO.
• GND: Connected to GND of Arduino UNO.
• ECHO: Connected to D3 of Arduino UNO.
• TRIG: Connected to D2 of Arduino UNO.

L298N DC Motor Driver

• GND: Connected to NEG of 3xAAA Battery Pack and GND of Arduino UNO.
• 12V: Connected to POS of 3xAAA Battery Pack.
• ENA: Connected to D11 of Arduino UNO.
• IN1: Connected to D10 of Arduino UNO.
• IN2: Connected to D9 of Arduino UNO.
• IN3: Connected to D8 of Arduino UNO.
• IN4: Connected to D7 of Arduino UNO.
• ENB: Connected to D6 of Arduino UNO.
• OUT1: Connected to pin 2 of DC Motor (Motor 2).
• OUT2: Connected to pin 1 of DC Motor (Motor 2).
• OUT3: Connected to pin 2 of DC Motor (Motor 1).
• OUT4: Connected to pin 1 of DC Motor (Motor 1).

Code Documentation

/*
 * Obstacle Avoidance Robot with Servo
 * This Arduino sketch controls two DC motors, a servo motor, and an ultrasonic
 * sensor to create an obstacle avoidance robot. The robot moves forward until
 * an obstacle is detected. When an obstacle is detected, the robot stops, the
 * servo rotates to scan for a clear path, and the robot turns in the direction
 * of the clear path.
 */

#include <Servo.h>

// Pin definitions
const int motor1Pin1 = 10;
const int motor1Pin2 = 9;
const int motor2Pin1 = 8;
const int motor2Pin2 = 7;
const int enA = 11;
const int enB = 6;
const int trigPin = 2;
const int echoPin = 3;
Servo myServo;

void setup() {
  // Initialize the digital pins as outputs
  pinMode(motor1Pin1, OUTPUT);
  pinMode(motor1Pin2, OUTPUT);
  pinMode(motor2Pin1, OUTPUT);
  pinMode(motor2Pin2, OUTPUT);
  pinMode(enA, OUTPUT);
  pinMode(enB, OUTPUT);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  myServo.attach(5); // Servo connected to pin 5
  Serial.begin(9600);
}

long readUltrasonicDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  return pulseIn(echoPin, HIGH) / 58.2; // Convert to cm
}

void moveForward() {
  digitalWrite(motor1Pin1, HIGH);
  digitalWrite(motor1Pin2, LOW);
  digitalWrite(motor2Pin1, HIGH);
  digitalWrite(motor2Pin2, LOW);
  analogWrite(enA, 255);
  analogWrite(enB, 255);
}

void moveBackward() {
  digitalWrite(motor1Pin1, LOW);
  digitalWrite(motor1Pin2, HIGH);
  digitalWrite(motor2Pin1, LOW);
  digitalWrite(motor2Pin2, HIGH);
  analogWrite(enA, 255);
  analogWrite(enB, 255);
}

void stopMotors() {
  digitalWrite(motor1Pin1, LOW);
  digitalWrite(motor1Pin2, LOW);
  digitalWrite(motor2Pin1, LOW);
  digitalWrite(motor2Pin2, LOW);
}

void turnLeft() {
  digitalWrite(motor1Pin1, LOW);
  digitalWrite(motor1Pin2, HIGH);
  digitalWrite(motor2Pin1, HIGH);
  digitalWrite(motor2Pin2, LOW);
  analogWrite(enA, 255);
  analogWrite(enB, 255);
}

void turnRight() {
  digitalWrite(motor1Pin1, HIGH);
  digitalWrite(motor1Pin2, LOW);
  digitalWrite(motor2Pin1, LOW);
  digitalWrite(motor2Pin2, HIGH);
  analogWrite(enA, 255);
  analogWrite(enB, 255);
}

void loop() {
  long distance = readUltrasonicDistance();
  if (distance < 20) { // If obstacle is closer than 20 cm
    stopMotors();
    delay(500);
    myServo.write(30); // Rotate servo to 30 degrees
    delay(500);
    long distanceLeft = readUltrasonicDistance();
    myServo.write(150); // Rotate servo to 150 degrees
    delay(500);
    long distanceRight = readUltrasonicDistance();
    myServo.write(90); // Center servo
    delay(500);
    if (distanceLeft > distanceRight) {