Apr 9, 2023 2 min read Projects

Motor Speed Control using an Arduino Uno

How to control the speed of your motor with an H-Bridge motor driver & Arduino Uno. Code and circuit diagram included.

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

Circuit Diagram

Adafruit Feather 32u4 Bluefruit LE and L9110H H-Bridge Motor Driver connected to a DC Motor. — Arduino Uno and L293D H-Bridge connected to a DC Motor.

Code

Click to see some 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);
}