STM32 Stepper Motor Control with ULN2003 Driver

Project Description

In this project, we demonstrate how to control a 28BYJ-48 stepper motor using an STM32F103C6 and the ULN2003 driver. The setup uses GPIO pins for coil control and buttons for direction control. A Proteus simulation is included for testing and validation.

What is the ULN2003?

The ULN2003 is a high-voltage, high-current Darlington transistor array designed to drive loads such as stepper motors, relays, and LEDs.

• 7 Darlington pairs → 500 mA per channel, 50V max.
• Logic-level inputs → Easily controlled by STM32 GPIO.
• Multiple outputs → Can drive several loads at once.
• Expandable → Outputs can be paralleled for higher current.
• Package → 16-pin DIP/TSSOP/SOIC.

Interfacing ULN2003 with 28BYJ-48 Stepper Motor

• The 28BYJ-48 is a unipolar stepper motor with 4 coils + 1 common wire (VCC).
• Coils (A, B, C, D) → Driven by ULN2003 outputs (IN1–IN4).
• Common wire → Connected to +5V.
• STM32 controls the coils by sending a sequence of signals via GPIO.

Control Logic

STM32CubeMX Setup

• MCU: STM32F103C6 (16 MHz clock)
• GPIO Configuration:

• -PB0–PB3 → Outputs (Coil control)
• -PA1–PA2 → Inputs (Buttons with pull-up)

• Generate initialization code in STM32CubeIDE.

STM32CubeIDE Implementation

Key Functions – Stepper Motor STM32

• main()

• -Initializes MCU and peripherals.
• -Runs infinite loop to read buttons and move motor.

• Stepper Sequence Array

• -const uint8_t turn[] = {0x02,0x06,0x04,0x0C,0x08,0x09,0x01,0x03};
• -Defines the half-step sequence for motor coils.

• Button Handling

Proteus Simulation

Required Components

• STM32F103C6
• ULN2003 Driver
• 28BYJ-48 Stepper Motor
• Push Buttons + Resistors

Connections

• PB0–PB3 → ULN2003 IN1–IN4
• PA1–PA2 → Buttons for direction control

Steps

• Load the.hex file from CubeIDE.
• Press forward/reverse buttons.
• Observe motor rotation in simulation.

That's all!

If you have any questions or suggestions don't hesitate to leave a comment below