This project demonstrates how to control the popular 28BYJ-48 5V stepper motor using an Arduino Uno and a ULN2003 driver board. Stepper motors are widely used in robotics, positioning systems, camera sliders, and automation projects where precise rotational control is required. Unlike ordinary DC motors, a stepper motor rotates in small angular increments, allowing accurate speed and position control.

Components Required

• Arduino Uno
• 28BYJ-48 Stepper Motor
• ULN2003 Driver Module
• Jumper Wires
• External 5V Power Supply

About the 28BYJ-48 Stepper Motor

The 28BYJ-48 is a low-cost 5V unipolar stepper motor equipped with an internal reduction gearbox, providing higher torque and improved positioning accuracy.

Specifications

• Operating Voltage: 5V
• Type: Unipolar Permanent Magnet Stepper Motor
• Number of Phases: 4
• Stride Angle: 5.625°
• Gear Reduction Ratio: Approximately 64:1
• Steps per Revolution (Full Step): 2048
• Steps per Revolution (Half Step): 4096
• Coil Resistance: 50 Ω ±7%

Operating Modes

1. Full-Step Mode (Single Coil Energized)

Only one winding is activated at a time.

Advantages

Lower power consumption

Reduced heat generation

Disadvantage

Lower torque

2. Full-Step Mode (Two Coils Energized)

Two phases are energized simultaneously.

Advantages

Maximum torque

Disadvantages

Higher current consumption

Increased vibration

3. Half-Step Mode

Alternates between one-phase and two-phase excitation.

Benefits

Smoother motion

Better resolution

Reduced vibration

The 28BYJ-48 commonly operates in half-step mode, providing 4096 steps per revolution.

Why Use the ULN2003 Driver?

The stepper motor requires significantly more current than an Arduino output pin can provide. The ULN2003 driver board acts as a current amplifier and allows the Arduino to safely energize the motor windings.

The module contains Darlington transistor arrays capable of driving loads up to 500 mA.

Working Principle

The motor contains four coils. By energizing these coils in sequence, the rotor aligns with the changing magnetic field and rotates step by step.

Changing the order of coil excitation determines the direction of rotation:

Clockwise rotation:

IN1 → IN2 → IN3 → IN4

Counter-clockwise rotation:

Reverse sequence

Circuit Diagram and Connections

The circuit consists of an Arduino Uno, a ULN2003 stepper motor driver module, and a 28BYJ-48 5V stepper motor. An external 5V power supply is connected to the VCC and GND pins of the ULN2003 module to provide sufficient current for the motor. The Arduino communicates with the driver through four digital pins, with D7, D6, D5, and D4 connected to IN1, IN2, IN3, and IN4, respectively. The GND pin of the Arduino is connected to the GND pin of the ULN2003 driver, and the ground of the external power supply is also connected to the same ground line to establish a common reference. The 28BYJ-48 stepper motor plugs directly into the connector provided on the ULN2003 board. During operation, the Arduino sends control signals to the ULN2003 driver, which amplifies these signals and energizes the motor coils in sequence, enabling precise control of the motor's speed and direction. Ensure that the power jumper on the ULN2003 module is installed for proper operation.

Step Calculation

The internal rotor requires 32 steps for one revolution.

Because the motor includes a gearbox with a reduction ratio close to 64:1:

32 × 64 = 2048 full steps

Therefore:

Full-step mode = 2048 steps/revolution

Half-step mode = 4096 steps/revolution

Features

• Accurate rotational control
• High torque because of gear reduction
• Low-cost solution
• Suitable for robotics and automation projects
• Simple interfacing with Arduino
• Supports forward and reverse rotation

Applications

Robotic arms

Camera pan and tilt systems

CNC and positioning systems

Automatic curtains

Small conveyor mechanisms

Educational projects

Home automation systems

Conclusion

The combination of the 28BYJ-48 stepper motor and ULN2003 driver provides an inexpensive and reliable solution for applications requiring controlled rotational movement. Using Arduino, both speed and direction can be easily controlled, making this setup ideal for beginners and makers.

For detailed explanation and code checkout tutorial published on Play with Circuit:

https://playwithcircuit.com/28byj48-stepper-motor-arduino-tutorial/

Play with Circuit publishes practical tutorials and projects related to Arduino, ESP32, embedded systems, and electronics.