Circuit Documentation

Summary

This circuit is designed to control a pair of DC gearmotors through an L298N motor driver module, with commands received via a Bluetooth HC-06 module. The Arduino UNO serves as the central microcontroller, interfacing with the Bluetooth module for wireless communication and the motor driver to control the motors' speed and direction. The power supply for the motor driver is provided by two 18650 Li-ion batteries, and a rocker switch is included to control the power flow. The circuit is intended for a small robotic vehicle that can move forward, backward, turn left, and right, and adjust its speed.

Component List

• Arduino UNO: A microcontroller board based on the ATmega328P, featuring digital and analog I/O pins.
• 18650 Li-ion Battery x 2: A pair of rechargeable lithium-ion batteries providing the power source for the motor driver.
• L298N DC Motor Driver: A module capable of driving two DC motors with direction and speed control.
• Gearmotor DC / Motorreductor: Four DC gearmotors that act as the actuators for the robotic vehicle's wheels.
• Bluetooth HC-06: A Bluetooth module for wireless serial communication, allowing remote control via Bluetooth-enabled devices.
• Rocker Switch: A switch to control the connection of the power supply to the circuit.

Wiring Details

Arduino UNO

• 5V connected to Bluetooth HC-06 VCC
• GND connected to:
  • Bluetooth HC-06 GND
  • L298N Motor Driver GND
• Vin connected to L298N Motor Driver 5V
• D13 connected to L298N Motor Driver IN1
• D12 connected to L298N Motor Driver IN2
• D11 connected to L298N Motor Driver IN3
• D10 connected to L298N Motor Driver IN4
• D9 connected to L298N Motor Driver ENA
• D8 connected to L298N Motor Driver ENB
• D1 connected to Bluetooth HC-06 RXD
• D0 connected to Bluetooth HC-06 TXD

18650 Li-ion Battery x 2

• + connected to Rocker Switch 2
• - connected to L298N Motor Driver GND

L298N DC Motor Driver

• 12V connected to Rocker Switch 1
• OUT1 and OUT2 connected to two Gearmotor DC Pin2 and Pin1 respectively
• OUT3 and OUT4 connected to the other two Gearmotor DC Pin2 and Pin1 respectively

Gearmotor DC / Motorreductor

• Four motors with Pin1 and Pin2 connected to L298N Motor Driver outputs OUT1, OUT2, OUT3, and OUT4.

Bluetooth HC-06

• VCC connected to Arduino UNO 5V
• GND connected to Arduino UNO GND
• TXD connected to Arduino UNO D0
• RXD connected to Arduino UNO D1

Rocker Switch

• 1 connected to L298N Motor Driver 12V
• 2 connected to 18650 Li-ion Battery x 2 +

Documented Code

// Define motor driver pins
int IN1 = 13;  // Motor A direction pin 1 (left forward)
int IN2 = 12;  // Motor A direction pin 2 (left backward)
int IN3 = 11;  // Motor B direction pin 1 (right forward)
int IN4 = 10;  // Motor B direction pin 2 (right backward)
int ENA = 9;   // Motor A speed pin (PWM)
int ENB = 8;   // Motor B speed pin (PWM)

// Bluetooth commands
char command;
int speed = 255;  // Default speed (high)

// Speed levels
const int LOW_SPEED = 100;
const int MEDIUM_SPEED = 180;
const int HIGH_SPEED = 255;

void setup() {
  // Set up motor pins as outputs
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);
  pinMode(ENA, OUTPUT);
  pinMode(ENB, OUTPUT);
  
  // Initialize Bluetooth communication
  Serial.begin(9600);  // HC-06 baud rate

  // Set initial speed
  analogWrite(ENA, speed); 
  analogWrite(ENB, speed); 
}

void loop() {
  // Check if there's a command from the Bluetooth module
  if (Serial.available() > 0) {
    command = Serial.read();  // Read the command

    // Movement control
    if (command == 'F') {
      moveForward();
    }
    else if (command == 'B') {
      moveBackward();
    }
    else if (command == 'L') {
      turnLeft();
    }
    else if (command == 'R') {
      turnRight();
    }
    else if (command == 'S') {
      stopCar();
    }

    // Speed control
    else if (command == '1') { // Low speed
      setSpeed(LOW_SPEED);
    }
    else if (command == '2') { // Medium speed
      setSpeed(MEDIUM_SPEED);
    }
    else if (command == '3') { // High speed
      setSpeed(HIGH_SPEED);
    }
  }
}

// Movement functions
void moveForward() {
  digitalWrite(IN1, HIGH); // Left motor forward
  digitalWrite(IN2, LOW);  // Left motor backward
  digitalWrite(IN3, HIGH); // Right motor forward
  digitalWrite(IN4, LOW);  // Right motor backward
}

void moveBackward() {
  digitalWrite(IN1, LOW);  // Left motor forward
  digitalWrite(IN2, HIGH); // Left motor backward
  digitalWrite(IN3, LOW);  // Right motor forward
  digitalWrite(IN4, HIGH); // Right motor backward
}

void turnLeft() {
  digitalWrite(IN1, HIGH);  // Left motor backward
  digitalWrite(IN2, LOW); // Left motor forward
  digitalWrite(IN3, LOW); // Right motor forward
  digitalWrite(IN4, HIGH);  // Right motor backward
}

void turnRight() {
  digitalWrite(IN1, LOW); // Left motor forward
  digitalWrite(IN2, HIGH);  // Left motor backward
  digitalWrite(IN3, HIGH);  // Right motor backward
  digitalWrite(IN4, LOW); // Right motor forward
}

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

// Function to set speed
void setSpeed(int newSpeed) {
  speed = newSpeed;
  analogWrite(ENA, speed);
  analogWrite(ENB, speed);
}

This code is designed to run on the Arduino UNO microcontroller. It initializes the motor driver pins and sets up the Bluetooth communication. The loop function listens for commands from the Bluetooth module to control the movement and speed of the motors. The movement functions moveForward, moveBackward, turnLeft, turnRight, and stopCar control the direction of the motors, while the setSpeed function adjusts the PWM signal to the motor driver for speed control.