Circuit Documentation

Summary

This circuit is designed to control a robot with the capability to move in different directions while avoiding obstacles. It utilizes three HC-SR04 ultrasonic sensors to detect obstacles from the front, left, and right directions. The L298N DC motor driver is used to control the gearmotors attached to the robot's wheels, allowing it to move forward, backward, and turn. The ESP32 microcontroller is the brain of the robot, processing sensor data and sending control signals to the motor driver. A 12V battery provides the power source for the motor driver and the ESP32, which in turn powers the sensors.

Component List

L298N DC Motor Driver

• Description: A module used for controlling up to two DC motors with a maximum current of 2A per channel.
• Purpose: To drive the gearmotors for the robot's wheels.

Gearmotor DC Wheels (Left and Right)

• Description: DC motors with gear reduction that provide torque for the robot's movement.
• Purpose: To act as the driving force for the robot's wheels.

Sensor HC-SR04 (x3)

• Description: Ultrasonic distance sensors that can measure distances by emitting ultrasonic waves and measuring the time taken for the echo to return.
• Purpose: To detect obstacles in front of, to the left of, and to the right of the robot.

Battery 12V

• Description: A 12V power source.
• Purpose: To provide power to the motor driver and the ESP32 microcontroller.

ESP32 38 PINS

• Description: A microcontroller with Wi-Fi and Bluetooth capabilities and a wide range of GPIO pins.
• Purpose: To process sensor data and control the motor driver based on the sensor inputs.

Wiring Details

L298N DC Motor Driver

• 5V connected to ESP32 5V (Power supply for logic)
• GND connected to Battery - (Ground connection)
• 12V connected to Battery + (Motor power supply)
• OUT1 and OUT2 connected to Right Gearmotor pins
• OUT3 and OUT4 connected to Left Gearmotor pins
• IN1, IN2, IN3, IN4 connected to ESP32 GPIOs G4, G16, G17, G5 respectively (Control signals from ESP32)

Gearmotor DC Wheels (Left and Right)

• Left Gearmotor connected to OUT3 and OUT4 of L298N
• Right Gearmotor connected to OUT1 and OUT2 of L298N

Sensor HC-SR04 (Front, Left, Right)

• All VCC pins connected to ESP32 5V (Power supply)
• All GND pins connected to Battery - (Ground connection)
• Front Sensor TRIG connected to ESP32 G34
• Front Sensor ECHO connected to ESP32 G35
• Left Sensor TRIG connected to ESP32 G32
• Left Sensor ECHO connected to ESP32 33
• Right Sensor TRIG connected to ESP32 G25
• Right Sensor ECHO connected to ESP32 G26

Battery 12V

• + connected to L298N 12V (Motor power supply)
• - connected to L298N GND and all HC-SR04 GND pins (Common ground)

ESP32 38 PINS

• 5V connected to all HC-SR04 VCC pins (Power supply for sensors)
• GND connected to Battery - (Common ground)
• GPIOs G34, G35, G32, 33, G25, G26 connected to corresponding HC-SR04 TRIG and ECHO pins
• GPIOs G4, G16, G17, G5 connected to L298N IN1, IN2, IN3, IN4 (Motor control signals)

Documented Code

/*
 * This code controls a robot that moves forward, backward, left, and right
 * to avoid obstacles using three HC-SR04 sensors positioned at the front,
 * left, and right. The L298N motor driver controls the motors, and the ESP32
 * microcontroller processes the sensor data and controls the motor driver.
 */

#define TRIG_FRONT 34
#define ECHO_FRONT 35
#define TRIG_LEFT 32
#define ECHO_LEFT 33
#define TRIG_RIGHT 25
#define ECHO_RIGHT 26
#define IN1 4
#define IN2 16
#define IN3 17
#define IN4 5

void setup() {
  pinMode(TRIG_FRONT, OUTPUT);
  pinMode(ECHO_FRONT, INPUT);
  pinMode(TRIG_LEFT, OUTPUT);
  pinMode(ECHO_LEFT, INPUT);
  pinMode(TRIG_RIGHT, OUTPUT);
  pinMode(ECHO_RIGHT, INPUT);
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);
}

long readDistance(int trigPin, int echoPin) {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  return pulseIn(echoPin, HIGH) * 0.034 / 2;
}

void moveForward() {
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}

void moveBackward() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, HIGH);
}

void turnLeft() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}

void turnRight() {
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, HIGH);
}

void stopMoving() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, LOW);
}

void loop() {
  long distanceFront = readDistance(TRIG_FRONT, ECHO_FRONT);
  long distanceLeft = readDistance(TRIG_LEFT, ECHO_LEFT);
  long distanceRight = readDistance(TRIG_RIGHT, ECHO_RIGHT);

  if (distanceFront < 20) {
    stopMoving();
    delay(500);
    if (distanceLeft < distanceRight) {
      turnRight();
    } else {
      turnLeft();
    }
    delay(500);
  } else {
    moveForward();
  }
  delay(100);
}

This code is responsible for initializing the GPIO pins connected to the HC-SR04 sensors and the L298N motor driver. It defines functions to read distances from the sensors and to control the motors for moving forward, backward, turning left, and turning right. The loop function continuously checks the distances from the sensors and decides the movement of the robot accordingly. If an obstacle is detected within 20 cm from the front sensor, the robot stops, determines the direction with more space (left or right), and turns accordingly. If no obstacle is detected, the robot moves forward.