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Arduino UNO R4 - DC Motor

In this guide, we will learn how to use the Arduino UNO R4 to control the DC motor. In detail, we will learn:

How a DC motor works
How to control the speed and direction of a DC motor.
How to control a DC motor with an L298N driver

Hardware Preparation

1	×	Arduino UNO R4 WiFi
1	×	Arduino UNO R4 Minima (Alternatively)
1	×	USB Cable Type-C
1	×	L298N Motor Driver Module
1	×	5V DC Motor
1	×	5V Power Adapter for 5V DC motor
1	×	DC Power Jack
1	×	Jumper Wires
1	×	(Recommended) Screw Terminal Block Shield for Arduino UNO R4
1	×	(Recommended) Breadboard Shield For Arduino UNO R4
1	×	(Recommended) Enclosure For Arduino UNO R4

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables.

Overview of DC Motor

DC Motor Pinout

A DC motor has two wires.

Positive wire: often red
Negative wire: often black

How It Works

When you purchase a DC motor, it's important to understand which voltage it operates on. For instance, consider a DC motor that works on 12 volts. When you connect the 12V DC motor to a 12Volt power source:

Connect 12V to the positive wire and GND to the negative wire: the DC motor will turn at full speed clockwise.
Connect 12V to the negative wire and GND to the positive wire: the DC motor will turn at full speed counterclockwise.

When you switch the connections on two wires of the DC motor as mentioned earlier, the direction it spins changes. This technique helps control the direction of DC motor. This isn't done by hand, but rather through programming.

If we give less than 12V to DC motors, the motor turns but not at full speed. This shows that changing the voltage changes the motor's speed. But, adjusting the voltage directly is hard in real situations. So, there is a simpler method to control the speed of DC motor. We keep the power supply voltage constant and use a PWM (Pulse Width Modulation) signal to control the motor speed. With a higher PWM duty cycle, the motor spins faster, and vice versa.

How to control DC motor using Arduino UNO R4

To control a DC motor, you need to control its speed and direction. The Arduino UNO R4 can create a PWM signal, but this signal is too weak in voltage and current to control the motor directly. Therefore, a hardware driver is needed to connect the Arduino UNO R4 to the DC motor. This driver performs two main tasks:

Increase the PWM signal's strength from the Arduino UNO R4 (both current and voltage) for controlling speed.
Receive the control signal from the Arduino UNO R4 to change the power supply's polarity for controlling direction.

※ NOTE THAT:

You can use this guide for any DC motor. We are using a 12V DC motor as an example.
When you use a 5V DC motor, even though the Arduino UNO R4 pin outputs 5V (the same voltage as the DC motor), you still need a driver between the Arduino UNO R4 and the DC motor. This is because the Arduino UNO R4 pin cannot supply enough current for the DC motor.

This tutorial will use the L298N driver to control DC motors.

Overview of L298N Driver

In this guide, we will learn how to use the L298N Driver to control a DC motor.

L298N Driver Pinout

The L298N Driver can independently control two DC motors at the same time, named motor A and motor B. It has 13 pins.

The common pins for both motors:

VCC pin: provides power to the motor. The voltage can range from 5 to 35V.
GND pin: this is a common ground pin and should be connected to GND (0V).
5V pin: powers the L298N module. It can use 5V provided by an Arduino UNO R4.

Motor A pins (Channel A):

ENA pins: These control the speed of Motor A. To adjust the speed, remove the jumper and connect the pin to a PWM input.
IN1 & IN2 pins: These determine the direction Motor A spins. If one pin is HIGH and the other is LOW, Motor A will spin. If both pins are either HIGH or LOW, Motor A will stop.
OUT1 & OUT2 pins: These are connected to Motor A.

Motor B pins (Channel B):

ENB pins: These control Motor B's speed. If you remove the jumper and connect these pins to a PWM input, you can adjust how fast Motor B spins.
IN3 & IN4 pins: These control the direction Motor B spins. If IN3 is HIGH and IN4 is LOW, or vice versa, Motor B will spin. If both are HIGH or both are LOW, Motor B will stop.
OUT3 & OUT4 pins: These are connected to Motor B.

The L298N driver mentioned earlier has two types of input power:

One for the DC motor (VCC and GND pins): from 5 to 35V.
One for running the L298N module itself (5V and GND pins): from 5 to 7V.

The L298N driver has three jumpers for more complex uses. For simplicity, please take all jumpers off the L298N driver.

We can control two DC motors at the same time using an Arduino UNO R4 and an L298N Driver. To control each motor, we use three pins from the Arduino UNO R4.

※ NOTE THAT:

This tutorial will show you how to control a DC motor using channel A. Controlling another DC motor is done in a similar way.

Wiring Diagram

Take off all three jumpers from the L298N module before you start the wiring.

This image is created using Fritzing. Click to enlarge image

How To Control the Speed of DC Motor via L298N Driver

You can easily adjust the speed of the DC motor by sending a PWM signal to the ENA pin on the L298N. Here is how to do it:

Connect an Arduino UNO R4 pin to the ENA pin on the L298N module.
Use the analogWrite() function to send a PWM signal to the ENA pin. The L298N driver will increase the strength of this PWM signal to power the DC motor.

analogWrite(ENA_PIN, speed); // Set motor speed on ENA_PIN, range 0-255

The speed can be any number from 0 to 255. At a speed of 0, the motor will stop. At a speed of 255, the motor will rotate at its highest speed.

How To Control the Direction of DC Motor via L298N Driver

The direction a motor rotates can be changed by setting IN1 and IN2 pins to HIGH or LOW. The table below shows how to control the direction for both channels.

IN1 pin	IN2 pin	Direction
LOW	LOW	Motor A stops
HIGH	HIGH	Motor A stops
HIGH	LOW	Motor A spins Clockwise
LOW	HIGH	Motor A spins Anti-Clockwise

Motor A rotates in a clockwise direction.

digitalWrite(IN1_PIN, HIGH); digitalWrite(IN2_PIN, LOW);

Motor A turns counter-clockwise

digitalWrite(IN1_PIN, LOW); digitalWrite(IN2_PIN, HIGH);

※ NOTE THAT:

If you connect the OUT1 and OUT2 pins to the DC motor pins in the opposite way, the motor will spin in the opposite direction. To fix this, simply switch the positions of the OUT1 and OUT2 pins, or change the control signals on the IN1 and IN2 pins in the program code.

How To Stop DC Motor Spinning

There are two methods to turn off a DC motor.

Sets the speed to zero.

analogWrite(ENA_PIN, 0);

Sets IN1 and IN2 pins to the same value (either LOW or HIGH).

digitalWrite(IN1_PIN, LOW); digitalWrite(IN2_PIN, LOW);

digitalWrite(IN1_PIN, HIGH); digitalWrite(IN2_PIN, HIGH);

How to control a DC motor using L298N driver.

Arduino UNO R4 Code

The code below does the following:

Make the DC motor go faster
Reverse the direction
Make the DC motor go slower
Stop the motor

/* * This Arduino UNO R4 code was developed by newbiely.com * * This Arduino UNO R4 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-uno-r4/arduino-uno-r4-dc-motor */ #define ENA_PIN 9 // The Arduino UNO R4 pin connected to the EN1 pin L298N #define IN1_PIN 6 // The Arduino UNO R4 pin connected to the IN1 pin L298N #define IN2_PIN 3 // The Arduino UNO R4 pin connected to the IN2 pin L298N void setup() { // initialize digital pins as outputs. pinMode(ENA_PIN, OUTPUT); pinMode(IN1_PIN, OUTPUT); pinMode(IN2_PIN, OUTPUT); } void loop() { digitalWrite(IN1_PIN, HIGH); // control motor A spins clockwise digitalWrite(IN2_PIN, LOW); // control motor A spins clockwise for (int speed = 0; speed <= 255; speed++) { analogWrite(ENA_PIN, speed); // control the speed delay(10); } delay(1000); // rotate at maximum speed 1 seconds in in clockwise direction // change direction digitalWrite(IN1_PIN, LOW); // control motor A spins anti-clockwise digitalWrite(IN2_PIN, HIGH); // control motor A spins anti-clockwise delay(1000); // rotate at maximum speed 1 seconds in in anti-clockwise direction for (int speed = 255; speed >= 0; speed--) { analogWrite(ENA_PIN, speed); // control the speed delay(10); } delay(1000); // stop motor 1 second }

Detailed Instructions

Follow these instructions step by step:

If this is your first time using the Arduino Uno R4 WiFi/Minima, refer to the tutorial on setting up the environment for Arduino Uno R4 WiFi/Minima in the Arduino IDE.
Wire the components according to the provided diagram.
Connect the Arduino Uno R4 board to your computer using a USB cable.
Launch the Arduino IDE on your computer.
Select the appropriate Arduino Uno R4 board (e.g., Arduino Uno R4 WiFi) and COM port.
Remove all three jumpers from the L298N module.
Paste the code into the Arduino IDE.
Press the Upload button in the Arduino IDE to upload the code to the Arduino UNO R4.
Observations:

The DC motor accelerates, then spins at maximum speed for 1 second.
The direction of the DC motor changes.
The DC motor spins at maximum speed for 1 second in the opposite direction.
The DC motor decelerates.
The DC motor stops for 1 second.
This sequence repeats continuously.

※ NOTE THAT:

In this tutorial, we will learn how to adjust the relative speed of a DC motor in relation to its highest speed. To control the absolute speed in rotations per second, we must use a PID controller and an encoder. We will cover how to control the precise speed of the DC motor in a different tutorial.

Video Tutorial

Function References

Learn More

Arduino UNO R4 - Servo Motor

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