Circuit Documentation

Summary

This circuit is designed to control an obstacle-avoiding robot. It uses an Arduino UNO as the central microcontroller to manage inputs and outputs, including signals to a servo motor and two DC motors through an L298N motor driver. An HC-SR04 ultrasonic sensor is used to detect obstacles. The robot changes direction when an obstacle is detected within a certain distance. A 3xAAA battery pack provides the power supply for the circuit.

Component List

Arduino UNO

• Microcontroller board based on the ATmega328P
• It has 14 digital input/output pins, 6 analog inputs, a 16 MHz quartz crystal, a USB connection, a power jack, an ICSP header, and a reset button.

DC Motor (x2)

• Electric motor that runs on direct current electricity.
• Used for driving the wheels of the robot.

Servo

• A rotary actuator or linear actuator that allows for precise control of angular or linear position, velocity, and acceleration.
• Used for steering the robot by changing direction.

HC-SR04 Ultrasonic Sensor

• An ultrasonic distance sensor that can measure distances from 2cm to 400cm with an accuracy of 3mm.
• Used for obstacle detection.

3xAAA Battery Pack with Switch and JST

• A battery holder for three AAA batteries with an integrated switch and JST connector.
• Provides power to the Arduino UNO and the motor driver.

L298N DC Motor Driver

• A high-power motor driver capable of driving up to 2A per channel.
• Used to control the speed and direction of the two DC motors.

Wiring Details

Arduino UNO

• 5V connected to the VCC of the HC-SR04 Ultrasonic Sensor and vcc of the Servo.
• GND connected to the gnd of the Servo, GND of the HC-SR04 Ultrasonic Sensor, GND of the L298N DC motor driver, and NEG of the 3xAAA Battery Pack.
• Vin connected to the POS of the 3xAAA Battery Pack and 12V of the L298N DC motor driver.
• Digital pins D2 to D11 are used to control the L298N motor driver and the Servo.

DC Motors

• Each motor has two pins (pin 1 and pin 2) connected to the OUT1, OUT2, OUT3, and OUT4 of the L298N motor driver.

Servo

• pulse connected to the D5 of the Arduino UNO.

HC-SR04 Ultrasonic Sensor

• TRIG connected to D2 and ECHO connected to D3 of the Arduino UNO.

L298N DC Motor Driver

• ENA and ENB connected to D11 and D6 of the Arduino UNO for enabling the motor outputs.
• IN1 to IN4 connected to D10, D9, D8, and D7 of the Arduino UNO for controlling motor direction.

3xAAA Battery Pack with Switch and JST

• NEG connected to the GND of the Arduino UNO and the L298N DC motor driver.
• POS connected to the Vin of the Arduino UNO and 12V of the L298N DC motor driver.

Documented Code

/*
 * This Arduino sketch controls an obstacle-avoiding robot with a servo motor.
 * The robot uses an HC-SR04 ultrasonic sensor to detect obstacles and a servo
 * motor to change direction. Two DC motors are used for movement, controlled
 * by an L298N motor driver. The robot stops and changes direction when an
 * obstacle is detected within a certain distance.
 */

#include <Servo.h>

// Pin definitions
const int trigPin = 2;
const int echoPin = 3;
const int servoPin = 5;
const int motor1Pin1 = 10;
const int motor1Pin2 = 9;
const int motor2Pin1 = 8;
const int motor2Pin2 = 7;
const int enA = 11;
const int enB = 6;

Servo myServo;

void setup() {
  // Initialize the motor control pins as outputs
  pinMode(motor1Pin1, OUTPUT);
  pinMode(motor1Pin2, OUTPUT);
  pinMode(motor2Pin1, OUTPUT);
  pinMode(motor2Pin2, OUTPUT);
  pinMode(enA, OUTPUT);
  pinMode(enB, OUTPUT);
  // Initialize the ultrasonic sensor pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  // Attach the servo motor
  myServo.attach(servoPin);
  // Start the servo at 90 degrees
  myServo.write(90);
}

void loop() {
  // Measure the distance to an obstacle
  long duration, distance;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration / 2) / 29.1;

  if (distance < 20) { // If an obstacle is detected within 20 cm
    // Stop the motors
    digitalWrite(motor1Pin1, LOW);
    digitalWrite(motor1Pin2, LOW);
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, LOW);
    // Turn the servo to look for a clear path
    myServo.write(0);
    delay(500);
    myServo.write(180);
    delay(500);
    myServo.write(90);
    // Reverse the motors to change direction
    digitalWrite(motor1Pin1, LOW);
    digitalWrite(motor1Pin2, HIGH);
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, HIGH);
    delay(1000);
  } else { // If no obstacle is detected
    // Move the motors forward
    digitalWrite(motor1Pin1, HIGH);
    digitalWrite(motor1Pin2, LOW);
    digitalWrite(motor2Pin1, HIGH);
    digitalWrite(motor2Pin2, LOW);
  }
}

This code is responsible for the operation of the obstacle-avoiding robot. It initializes the pins, sets up the servo, and controls the motors based on the distance readings from the ultrasonic sensor. The robot moves forward until an obstacle is detected within 20 cm, at which point it stops, looks for a clear path with the servo, and then reverses direction.