Lesson 129: Spinning Up - Controlling DC Motors with the L298N Driver

Servos are fantastic for precise, twitchy movements, but what if you want to build a wheeled robot or a motorized fan that spins continuously? You need a standard DC Motor. Here’s the catch: DC motors are power-hungry monsters. Connect one directly to your Arduino, and you will instantly fry your microcontroller into an expensive paperweight. To safely tame this beast, we use a Motor Driver. The L298N is big, clunky, and perfectly suited for the job. The L298N driver acts as a heavy-duty switch, taking small control signals from the Arduino and delivering high power to the motors.

What You’ll Need

• An Arduino board (like the ELEGOO UNO R3)
• An L298N Motor Drive Controller Board Module
• A DC Gear Motor TT Motor with Wheel
• Breadboard Jumper Wires
• A separate power supply (like a 4xAA battery pack) for the motors

How the L298N Works

The L298N uses a circuit called an “H-Bridge” to control both the speed and direction of up to two DC motors.

It has three main types of connections:

1. Power In: You connect your battery pack (e.g., 6V-12V) to the 12V terminal, and the battery ground to the GND terminal. Always connect the Arduino’s GND to this same GND terminal to complete the circuit!
2. Motor Out: The output terminals (OUT1 and OUT2 for Motor A, OUT3 and OUT4 for Motor B) connect to your DC motor’s wires.
3. Logic In: These pins (IN1, IN2, ENA, etc.) connect to your Arduino. They tell the L298N which way to spin and how fast.

Wiring It Up

Let’s wire up a single motor (Motor A).

1. Connect the Motor to OUT1 and OUT2.
2. Connect your Battery Pack Positive to the 12V terminal on the L298N.
3. Connect your Battery Pack Negative to the GND terminal.
4. Connect the Arduino GND to the same GND terminal on the L298N.
5. Remove the little black jumper cap on the ENA pin (if present).
6. Connect ENA to Arduino Pin 9 (for speed control via PWM).
7. Connect IN1 to Arduino Pin 8 (direction control 1).
8. Connect IN2 to Arduino Pin 7 (direction control 2).

The Code: Speed and Direction

To control direction, we set IN1 and IN2 to opposite states (one HIGH, one LOW). Reversing those states reverses the motor. To control speed, we use analogWrite() on the ENA pin, sending a value between 0 (stopped) and 255 (full speed).

// Define the L298N control pins
const int enA = 9;
const int in1 = 8;
const int in2 = 7;

void setup() {
  // Set all the motor control pins to outputs
  pinMode(enA, OUTPUT);
  pinMode(in1, OUTPUT);
  pinMode(in2, OUTPUT);
  
  // Start with the motor turned off
  digitalWrite(in1, LOW);
  digitalWrite(in2, LOW);
  analogWrite(enA, 0);
}

void loop() {
  // 1. Spin forward at full speed
  digitalWrite(in1, HIGH);
  digitalWrite(in2, LOW);
  analogWrite(enA, 255); // Full speed
  delay(2000); // Wait for 2 seconds

  // 2. Stop
  digitalWrite(in1, LOW);
  digitalWrite(in2, LOW);
  analogWrite(enA, 0);
  delay(1000);

  // 3. Spin backward at half speed
  digitalWrite(in1, LOW);
  digitalWrite(in2, HIGH);
  analogWrite(enA, 128); // Half speed
  delay(2000);

  // 4. Stop again
  digitalWrite(in1, LOW);
  digitalWrite(in2, LOW);
  analogWrite(enA, 0);
  delay(1000);
}

Upload the code and watch your motor come to life! In future lessons, we can connect a second motor and pair it with an ultrasonic sensor to build an autonomous robot car.