Motor Speed Control using an Arduino Uno

Below we'll demonstrate how to control the speed of your DC motor using an Arduino Uno and an L293D H-Bridge. The H-Bridge is also capable of controlling two motors at the same time. (Not demoed below)

Using the Serial Monitor, you'll be able to send a certain character to your Arduino to set the desired speed. These can, of course, be changed in the code to your needs.

Required Components

• Arduino Uno
• L293D H-Bridge Driver
• DC motor

Circuit Diagram

Code

//Motor_1 Connection
#define ENABLE_1    11
#define MOTOR_1_A   10
#define MOTOR_1_B   9

//other variables
char serial_data;

void setup()
{
    Serial.begin(9600);
    Serial.println("Motor Init..");
    motor_1_init();
    Serial.println("Motor Ready!");
}

 
void loop()
{
    while (Serial.available())
    {
      serial_data = Serial.read();
      switch (serial_data)
      {
        case 'w':
            analogWrite(ENABLE_1, 255);
            digitalWrite(MOTOR_1_A, HIGH);
            digitalWrite(MOTOR_1_B, LOW);
            Serial.println("100% forward Motor_1");
            break; 
        case 'e':
            analogWrite(ENABLE_1, 128);
            digitalWrite(MOTOR_1_A, HIGH);
            digitalWrite(MOTOR_1_B, LOW);
            Serial.println("50% Forward Motor_1");
            break;
        case 's':
            analogWrite(ENABLE_1, 0);
            digitalWrite(MOTOR_1_A, HIGH);
            digitalWrite(MOTOR_1_B, LOW);
            Serial.println("0% forward Motor_1");
            break; 
        case 'd':
            analogWrite(ENABLE_1, 128);
            digitalWrite(MOTOR_1_A, LOW);
            digitalWrite(MOTOR_1_B, HIGH);
            Serial.println("50% Backward Motor_1");
            break; 
        case 'f':
            analogWrite(ENABLE_1, 255);
            digitalWrite(MOTOR_1_A, LOW);
            digitalWrite(MOTOR_1_B, HIGH);
            Serial.println("100% Backward Motor_1");
            break; 
        default:
            break;
        }
    }
}

 //-------------- functions -------------------------------------

void motor_1_init()
{
  pinMode(MOTOR_1_A, OUTPUT);
  pinMode(MOTOR_1_B, OUTPUT);
  pinMode(ENABLE_1, OUTPUT);
 
  digitalWrite(MOTOR_1_A, LOW);
  digitalWrite(MOTOR_1_B, LOW);
  analogWrite(ENABLE_1, LOW);
}

Wiring

Using the L293D datasheet and the documentation for Arduino Uno, you can find out pin definitions and how to connect them.

See the table below for how I did it:

You can also use this driver, L293D, to drive two motors at once. Check the datasheet to see how to connect it; it's very similar.

Results

Here you can see a video of the motor running the above setup.

Thank you for reading!

Hopefully, this has given you a decent starting point for your own project.