---

User’s Guide

28BYJ‑48 Stepper Motor + ULN2003 Driver Board

---

1. Product Overview

• 28BYJ‑48 Stepper Motor
  • Type: Unipolar stepper motor
  • Voltage: 5V DC (common version)
  • Steps per revolution: ~2048 (with internal gear reduction)
  • Wires: 5 (Red, Orange, Yellow, Blue, Pink)
• ULN2003 Driver Board
  • IC: ULN2003A (Darlington transistor array)
  • Inputs: IN1–IN4 (logic signals from microcontroller to motor driver, other IN5 – IN7 inputs exposed on the other header pins)
  • Outputs: Drive motor coils via white connector
  • Power: VCC (5V), GND

---

2. Pinout

ULN2003 Driver Board

Pin	Function
IN1–IN4	Control inputs from Arduino/ESP32/etc.
VCC	+5V supply
GND	Ground
Motor Connector	White socket for 28BYJ‑48 motor wires

28BYJ‑48 Motor Wire Colors

Wire Color	Coil
Red	Common (VCC)
Orange	Coil A
Yellow	Coil B
Pink	Coil C
Blue	Coil D

---

3. How It Works

• The ULN2003 board takes low‑power signals from a microcontroller and safely drives the motor coils.
• The motor rotates step by step when IN1–IN4 are activated in sequence.
• By changing the sequence and timing, you control direction and speed.

---

4. Wiring Guide (Arduino Example)

1. Connect VCC on ULN2003 → Arduino 5V.
2. Connect GND on ULN2003 → Arduino GND.
3. Connect IN1–IN4 → Arduino digital pins (e.g., D8–D11).
4. Plug the motor’s white connector into the ULN2003 board.

---

5. Example Arduino Code

#include <Stepper.h>

const int stepsPerRevolution = 2048; // 28BYJ-48 with gear reduction
Stepper myStepper(stepsPerRevolution, 8, 10, 9, 11);

void setup() {
  myStepper.setSpeed(10); // RPM
}

void loop() {
  myStepper.step(stepsPerRevolution); // one full rotation clockwise
  delay(1000);
  myStepper.step(-stepsPerRevolution); // one full rotation counterclockwise
  delay(1000);
}

---

6. Applications

• Educational kits: Demonstrating stepper motor control.
• Robotics: Precise positioning for arms or wheels.
• Automation: Small actuators, dials, or indicators.
• DIY projects: Rotating displays, camera sliders, or tuning knobs.

---

7. Best Practices

• Always use 5V regulated supply for the motor.
• Avoid driving directly from Arduino pins — always use the ULN2003 board.
• Stepper motors draw current even when stationary; disconnect power if not in use.
• For smoother motion, use half‑step or microstepping sequences.

8. Miscellaneous Info

• Standard ULN2003 boards for the 28BYJ‑48 stepper usually expose IN1–IN4, because the motor only needs 4 control signals.
• However, the ULN2003 chip itself has 7 Darlington transistor channels. That means it can drive up to 7 separate loads (LEDs, relays, coils, etc.).
• Some board designs break out all 7 inputs (IN1–IN7) and their corresponding outputs, even though the 28BYJ‑48 motor only uses 4.

How It Relates to Your Motor

• For the 28BYJ‑48 stepper motor, you only need IN1–IN4. These connect to the motor’s 4 coils via the white connector.
• The extra inputs (IN5–IN7) are not used for this motor. They’re just exposed in case you want to drive other devices with the same board.

---

 

Was this article helpful?

0 0

Please Share Your Feedback

How Can We Improve This Article?

Name

Email

Submit