Stepper Motor Driver
Signal Type:
IDeATe Component Number:
Receives motion instructions from the Arduino, and provides power to the Stepper Motor.
Stepper Motor Driver

The stepper motor driver allows for controlling a stepper motor using digital pins. This module is essentially 4 transistor in one board. The transistors take the low-power signal from the inputs and repeat them at higher power to drive the stepper motor. This particular module uses the ULN2003 chip.

For more information on how a stepper motor works, please see the Stepper Motor page. For information on how a transistor works, please see the transistor page.

Getting started
Stepper Motor Driver Schematic
For this example, the Stepper Motor Driver is connected to pins 7, 8, 9, and 10

This code requires the AccelStepper library. You can install it in the Arduino IDE by going to Sketch > Include Library > Manage Libraries and searching for "AccelStepper." This library handles all of the code to convert position instructions to steps of each stepper motor coil.

 * This program sets up a stepper motor and moves it back and
 * forth between two positions.
 * Initially by Robert Zacaharias from
 * Modified 2021-02-19 by Perry Naseck

#include <AccelStepper.h>

const int stepperPin1 = 7;  // Digital pin for IN1 of the stepper motor driver
const int stepperPin2 = 8;  // Digital pin for IN2 of the stepper motor driver
const int stepperPin3 = 9;  // Digital pin for IN3 of the stepper motor driver
const int stepperPin4 = 10; // Digital pin for IN4 of the stepper motor driver

// Setup the ULN2003 stepper motor driver with the correct pins
AccelStepper myStepper(AccelStepper::FULL4WIRE,

// Variables to set two positions to move between (measured in steps relative to
// the starting position):
// Since the stepper motor can turn infinitely, there is not an upper or lower
// limit. A negative number will move in the opposite direction from the starting
// point.
int pos1 = 10000; // 10000 means 50 full rotations if the motor has 200 steps/revolution
int pos2 = -273;

// Variable to keep track of where the stepper currently is
int currentPos;

void setup() {
  // Setup serial port to send the current position back to the computer

  // Set a maximum speed amd a starting acceleration
  myStepper.setMaxSpeed(1000);    // measured in steps per second
  myStepper.setAcceleration(500); // measured in steps per second squared

void loop() {
  // Store where the stepper currently is (number of steps from the starting point)
  currentPos = myStepper.currentPosition();

  // If the stepper has arrived at its destination
  if (myStepper.distanceToGo() == 0) {
    // Tell the computer where the stepper motor arrived at
    Serial.print("arrived at position: ");

    if (currentPos == pos1) {
      // If the stepper is at for pos1, then go to pos2
    else {
      // Otherwise, go to pos1

  // This function actually moves the stepper motor after the next destination has
  // been set. This should be called as often as possible so that the motor moves
  // smoothly. In this example, this function will be called every time the loop()
  // runs. This function determines if the motor should move one step and moves it
  // if it needs to. Whether or not it takes a step depends on the set speed and
  // acceleration.;
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