Project 2: Controlling Stepper Motor via Serial Monitor – 28BYJ-48 Stepper Motor

This article is the second installment of an 8-part tutorial on controlling the 28BYJ-48 stepper motor using Arduino. In this project, we introduce serial communication as a method of user input. Using the Arduino Serial Monitor, users can input commands to rotate the motor in either direction.

All source code and wiring diagrams related to this project are available for download at the end of this article.

📘 Introduction

This project expands on basic motor control by enabling real-time interaction via the Serial Monitor. Rather than hardcoding rotation logic into the loop(), the user enters a command through the monitor to make the motor turn forward or backward. This is ideal for debugging or creating interactive testing tools for hardware setups.

⚙️ Wiring Diagram

The hardware setup remains unchanged from Project 1. The 28BYJ-48 stepper motor connects to the ULN2003 driver, which then interfaces with the Arduino as follows:

• IN1 → Arduino pin 8

• IN2 → Arduino pin 9

• IN3 → Arduino pin 10

• IN4 → Arduino pin 11

• Power and GND to ULN2003 from Arduino

Caption: Project 2 wiring using ULN2003 and Arduino Uno. Same configuration as Project 1.

💻 Code Explanation

The code introduces Serial.readStringUntil() to accept user input from the Serial Monitor:

1. Stepper Setup:

#include <Stepper.h>
const int stepsPerRevolution = 2048;
Stepper myStepper(stepsPerRevolution, 8, 10, 9, 11);

2 Initialization

void setup() {
  myStepper.setSpeed(10);
  Serial.begin(9600);
  Serial.println("Enter direction: f=forward, r=reverse");
}

3. Main Loop with Serial Input:

void loop() {
  if (Serial.available()) {
    String input = Serial.readStringUntil('\n');
    input.trim();

    if (input == "f") {
      myStepper.step(stepsPerRevolution);
    } else if (input == "r") {
      myStepper.step(-stepsPerRevolution);
    } else {
      Serial.println("Invalid input. Use 'f' or 'r'.");
    }
  }
}

• f causes one full forward revolution.

• r reverses one full revolution.

This adds basic text-based control for interactive stepper testing.

🎬 Timestamps from Full Video

Reference the full tutorial video for this project at the following timestamps:

• 22:23 – Project 2: Introduction and code explanation

• 32:03 – Project 2: Demonstration using Serial Monitor

📁 Download Section

The code and wiring schematic for this project can be downloaded below. These resources will help you build, test, and adapt the Serial Monitor-controlled stepper motor in your own projects.

Next up is [Project 3: Stepper Motor Control Using Push Button STPB-1].