Experiment 7: Stepper Motor Control via Microcontroller ESP32

Objective

To control the rotation and direction of a stepper motor using ESP32 and a ULN2003 driver.

Task

Connect stepper motor and driver to ESP32.
Write code to rotate motor clockwise and counter-clockwise.
Vary delay to change motor speed.

⚠️ Disconnect your ESP32 from the computer while making or removing component connections.

⚠️ Important Note:
1. Connect only the ESP32 (without any component connections) to the computer via USB.
2. Upload the code to the ESP32.
3. Disconnect the ESP32 from the computer and remove the USB cable.
4. Make all component connections using patch cords as per the circuit diagram.
5. Then connect the 9V adapter to provide external power supply to the stepper motor.

Circuit Diagram

Board Connections

Connections (without LCD)

Component	ESP32 Pin	Description
Stepper Motor IN1	12	Control input 1
Stepper Motor IN2	13	Control input 2
Stepper Motor IN3	14	Control input 3
Stepper Motor IN4	15	Control input 4
ULN2003 VCC	External Power Supply VCC	Power supply for driver
ULN2003 GND	External Power Supply GND	Common ground

ESP32 Code

// © 2025, Cognifront. Member of The IoT Kits Family.
// Experiment 7: Stepper Motor Control via Microcontroller (ESP32 Version)

#include <Stepper.h>

// Number of steps per revolution for 28BYJ-48 stepper motor
const int stepsPerRevolution = 2048;

// Define stepper motor control pins (connected to ULN2003 driver)
const int IN1 = 12;
const int IN2 = 13;
const int IN3 = 14;
const int IN4 = 15;

// Create Stepper object (sequence must be IN1, IN3, IN2, IN4 for 28BYJ-48)
Stepper myStepper(stepsPerRevolution, IN1, IN3, IN2, IN4);

void setup() {
  Serial.begin(115200);
  delay(1000);

  Serial.println("\n=== Stepper Motor Speed Test (ESP32) ===");
}

void loop() {
  // Rotate Counterclockwise (CCW) at 5 and 10 RPM
  for (int spd = 5; spd <= 10; spd += 5) {
    myStepper.setSpeed(spd);
    Serial.print("Direction: CCW | Speed: ");
    Serial.print(spd);
    Serial.println(" RPM");

    myStepper.step(stepsPerRevolution / 2); // Half revolution
    delay(500);
  }

  // Rotate Clockwise (CW) at 10 and 5 RPM
  for (int spd = 10; spd >= 5; spd -= 5) {
    myStepper.setSpeed(spd);
    Serial.print("Direction: CW | Speed: ");
    Serial.print(spd);
    Serial.println(" RPM");

    myStepper.step(-stepsPerRevolution / 2); // Half revolution
    delay(500);
  }
}

Observation

The stepper motor rotates in both clockwise and counterclockwise directions.
The motor speed changes as per the programmed RPM values.
Smooth operation is observed with correct wiring sequence.

Conclusion

The experiment successfully demonstrates control of a stepper motor’s speed and direction using ESP32 and a ULN2003 driver. This forms the basis for applications like robotic motion control, CNC systems, and precise positioning mechanisms.

Real Life Example

CNC Machine Feed Drive: Stepper motors provide precise and repeatable control of tool or table movement along X, Y, and Z axes, ensuring accurate machining operations in computer-controlled manufacturing.