Control one or more stepper motors using 74HC595 shift registers while consuming only 3 microcontroller pins.

This library is designed for Arduino & PlatformIO projects where pin count is limited and multiple stepper motors are needed.

• ✅ Uses only 3 MCU pins (DATA, CLOCK, LATCH)
• ✅ Supports multiple chained 74HC595 shift registers
• ✅ Drive multiple stepper motors simultaneously
• ✅ Familiar Arduino Stepper-style API
• ✅ Blocking and non-blocking (async) stepping modes
• ✅ No dynamic memory (safe for AVR)
• ✅ Works with ULN2003, L293D, L298, MOSFET drivers

⚠ DO NOT connect stepper motors directly to the 74HC595

The 74HC595 can only output logic signals.

You must use a motor driver, such as:

• ULN2003 (recommended for 28BYJ-48)
• L293D / L298
• Discrete MOSFET or transistor arrays

This library is available in the PlatformIO Registry.

Add it to your platformio.ini:

lib_deps =
  mussacharles60/StepperShiftRegister74HC595@^1.0.2

PlatformIO will auto-import it.

Project structure: (If you want to add this library manually)

your-project/
├── lib/
│ └── StepperShiftRegister74HC595/
├── src/
│ └── main.cpp

PlatformIO will auto-detect it.

Each stepper motor uses 4 outputs:

Q0 → IN1 Q1 → IN2 Q2 → IN3 Q3 → IN4

With chained shift registers, pin numbering continues:

• First IC: 0–7
• Second IC: 8–15
• Third IC: 16–23
• etc.

ShiftRegister74HC595<Size>

Size = number of 74HC595 ICs chained together.

Examples:

• Size = 1 → 8 outputs
• Size = 2 → 16 outputs
• Size = 3 → 24 outputs

Current implementation:

• ✔ Full-step (4-step sequence)
• Planned / Easy to add:
• Half-step (8-step)

Custom stepping tables

• Microstepping (with DAC or PWM drivers)

⚠ The step() function is blocking, exactly like Arduino’s original Stepper library.

This means:

• While stepping, other code is paused

• Not suitable for time-critical multitasking

#include <Arduino.h>
#include <ShiftRegister74HC595.h>
#include <StepperShiftRegister74HC595.h>

// 2 shift registers = 16 outputs
ShiftRegister74HC595<2> sr(2, 3, 4);  // (data pin, clock pin, latch pin)

StepperShiftRegister74HC595<2> motor1(2048, sr, 0, 1, 2, 3);
StepperShiftRegister74HC595<2> motor2(2048, sr, 4, 5, 6, 7);
StepperShiftRegister74HC595<2> motor3(2048, sr, 8, 9, 10, 11);

void setup() {
  motor1.setSpeed(15);  // RPM
  motor2.setSpeed(12);
  motor3.setSpeed(10);
}

void loop() {
  motor1.step(200);
  motor2.step(-100);
  motor3.step(50);
  delay(500);
}

If you need:

• Non-blocking control
• Acceleration
• Multi-axis sync

👉 Ask for an async version

This means:

• The motor moves in the background
• Your program continues running

Ideal for:

• Multiple stepper motors
• Sensors
• WiFi / BLE
• Displays
• Real-time systems (ESP32, ESP8266)

✅ The stepAsync() function is non-blocking.

⚠️ Important: You must call update() repeatedly (usually inside loop()) for the motor to advance.

#include <Arduino.h>
#include <ShiftRegister74HC595.h>
#include <StepperShiftRegister74HC595.h>

// 2 shift registers = 16 outputs
ShiftRegister74HC595<2> sr(2, 3, 4);  // (data pin, clock pin, latch pin)

StepperShiftRegister74HC595<2> motor1(2048, sr, 0, 1, 2, 3);
StepperShiftRegister74HC595<2> motor2(2048, sr, 4, 5, 6, 7);
StepperShiftRegister74HC595<2> motor3(2048, sr, 8, 9, 10, 11);

void setup() {
  motor1.setSpeed(15);  // RPM
  motor2.setSpeed(12);
  motor3.setSpeed(10);

  // Start motors asynchronously
  motor1.stepAsync(200);
  motor2.stepAsync(-100);
  motor3.stepAsync(50);
}

void loop() {
  // Update motors (VERY IMPORTANT) MUST be called often
  motor1.update();
  motor2.update();
  motor3.update();

  if (!motor1.isRunning()) {
    // do something when finished
  }

  if (!motor2.isRunning()) {
    // do something when finished
  }

  if (!motor3.isRunning()) {
    // do something when finished
  }

  // Other functions logics goes here...
}

• step(steps)

  • Blocks until movement is complete
  • Compatible with Arduino Stepper behavior

• stepAsync(steps)

  • Non-blocking
  • Requires update() to be called frequently
  • Ideal for ESP32, WiFi, sensors, UI, and multitasking

• Suitable up to ~500–800 steps/sec total
• SPI-based shift register control is faster (future upgrade)

• Arduino Uno / Nano
• ESP32
• ESP8266
• 28BYJ-48 + ULN2003
• Bipolar steppers via L293D

MIT License Free to use, modify, and distribute.

Copyright (c) 2025 Mussa Charles

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

• Arduino Stepper Library (original logic)
• ShiftRegister74HC595 Library by Timo Denk
• Custom integration by Mussa Charles

• Non-blocking motion engine (async stepping)
• Half-step mode Higher resolution, smoother motion
• SPI backend Hardware SPI for faster shift register updates
• Acceleration / deceleration (ramp profiles) Avoid missed steps at high speed
• Central motor manager Single update loop for many motors
• Stepper driver abstraction ULN2003, H-bridge, custom drivers