Circuit Documentation

Summary of the Circuit

This circuit is designed to control an obstacle-avoiding robot. It uses an Arduino UNO as the central microcontroller to process inputs from an HC-SR04 ultrasonic sensor and outputs commands to a servo motor and two DC motors through an L298N motor driver. The robot is powered by two 18650 Li-ion batteries connected in series, with a rocker switch (SPST) to control the power flow. The ultrasonic sensor detects obstacles, and the servo motor adjusts the robot's direction accordingly. The DC motors drive the robot's wheels, allowing it to move and change direction based on sensor input.

Component List

Arduino UNO

• Microcontroller board based on the ATmega328P
• Used for processing sensor data and controlling the motors and servo

Servo

• A motor capable of precise position control
• Used to change the robot's direction by adjusting its orientation

HC-SR04 Ultrasonic Sensor

• A sensor that measures distance using ultrasonic waves
• Used to detect obstacles in the robot's path

L298N DC Motor Driver

• A module capable of driving two DC motors
• Used to control the speed and direction of the robot's motors

18650 Li-ion Battery x 2

• Rechargeable batteries providing the power source for the circuit
• Used to supply power to the Arduino, motors, and sensors

Rocker Switch (SPST)

• A single-pole single-throw switch
• Used to turn the robot's power on and off

Hobby Gearmotor with 48:1 Gearbox (x2)

• DC motors with a gearbox for increased torque
• Used to drive the robot's wheels

Wiring Details

Arduino UNO

• 5V connected to HC-SR04 VCC and Servo VCC
• GND connected to HC-SR04 GND, Servo GND, and L298N GND
• Vin connected to the output of the Rocker Switch
• D11 connected to L298N ENA
• D10 connected to L298N IN1
• D9 connected to L298N IN2
• D8 connected to L298N IN3
• D7 connected to L298N IN4
• D6 connected to L298N ENB
• D5 connected to Servo pulse
• D3 connected to HC-SR04 ECHO
• D2 connected to HC-SR04 TRIG

Servo

• gnd connected to Arduino GND
• vcc connected to Arduino 5V
• pulse connected to Arduino D5

HC-SR04 Ultrasonic Sensor

• GND connected to Arduino GND
• VCC connected to Arduino 5V
• ECHO connected to Arduino D3
• TRIG connected to Arduino D2

L298N DC Motor Driver

• GND connected to Arduino GND
• 12V connected to the output of the Rocker Switch
• ENA connected to Arduino D11
• IN1 connected to Arduino D10
• IN2 connected to Arduino D9
• IN3 connected to Arduino D8
• IN4 connected to Arduino D7
• ENB connected to Arduino D6
• OUT1 connected to Gearmotor 1 pin 1
• OUT2 connected to Gearmotor 1 pin 2
• OUT3 connected to Gearmotor 2 pin 1
• OUT4 connected to Gearmotor 2 pin 2

18650 Li-ion Battery x 2

• + connected to Rocker Switch pin 2
• - connected to L298N GND

Rocker Switch (SPST)

• 1 connected to L298N 12V and Arduino Vin
• 2 connected to the positive terminal of the 18650 Li-ion Battery x 2

Hobby Gearmotor with 48:1 Gearbox

• Gearmotor 1 pin 1 connected to L298N OUT1
• Gearmotor 1 pin 2 connected to L298N OUT2
• Gearmotor 2 pin 1 connected to L298N OUT3
• Gearmotor 2 pin 2 connected to L298N OUT4

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 continuously checks for obstacles using the ultrasonic sensor. When an obstacle is detected, the robot stops, the servo scans for a clear path, and then the robot reverses direction. If no obstacle is detected, the robot continues to move forward.