Simple stepper motor driver library utilizing SPI to send control signals through a shift register.
Mainly built for the ATtiny line of microcontrollers but works with Arduino and ESP32 boards (probably more)

• Adjustable delay to enable different motor speeds
• Non-blocking code
• Returns true after each step to allow for accurate step counting (can be used without caring about this)

• ULN2003 driver board for 28BYJ-48.
• Probably any 4-wire stepper motors (no guarantee)

Uses the standard CLK and MOSI pins connected to the CLK and SER(data) pins on the shift register.
You can choose any pin for CS(latch).

            74HC595N
             __   __
IN2 <-  QB =|1 *-*16|= vcc  <- +5v
IN3 <-  QC =|2    15|= QA   -> IN1
IN4 <-  QD =|3    14|= SER  <- MOSI
IN1 <-  QE =|4    13|= OE   -> GND
IN2 <-  QF =|5    12|= RCK  <- LATCH
IN3 <-  QG =|6    11|= SCK  <- SCK
IN4 <-  QH =|7    10|= SCLR <- +5v
GND <- GND =|8_____9|= SQH

#include <Stepper595.h>

#define LATCH 4

Stepper595 stepper(LATCH);
int steps = 0;

void setup()
{}

void loop()
{
    if (stepper.step(MOTOR_1, CW) steps++);
}

• Stepper595.step(motor, direction)
  • steps the motor by a single step
  • motor = MOTOR_1 or MOTOR_2 ( 0 or 1 )
  • direction = CCW or CW ( 0 or 1 )
  • returns true if step has occured, though this can be ignored if not needed (useful for counting steps)
• Stepper595.setDelay(delay)
  • sets the delay between steps in milliseconds
  • maximum delay is 255 ( essentially 4 steps a second, very slow )
• Stepper595.stop(motor)
  • argument is optional
  • motor = MOTOR_1 or MOTOR_2 ( 0 or 1 )
  • with no argument (Stepper595.stop()) it will disable all control signals

• Microcontroller or dev board with SPI support
• Stepper motor driver w/ board (optional)
• Stepper motor