/*NOTES:

Items named "VCC" and GND are the external power suitable for the stepper requirements, + connected to VMOT

The A4988 driver "VDD" pin is connected to the arduino/attiny 5v

When applying in real life, ensure current limiting pot is set to approx 
0.6-0.8v (measured across pot wiper and any ground)

ALL grounds must be connected, even from the external PSU
*/

#include <AccelStepper.h>

const byte motStep = 11;
const byte motDir = 12;
int mm = 0;
float mmSteps = 200;  // Arbitrary number of steps per mm of axis travel - Change to suit
AccelStepper stepper(AccelStepper::DRIVER, motStep, motDir);

void setup() {
  pinMode(motStep, OUTPUT);
  pinMode(motDir, OUTPUT);
  stepper.setMaxSpeed(400.0);
  stepper.setAcceleration(200.0);
}

// Single function to move the motor x number of mm (steps per mm * mm requested)
void motMove(int mm) {
  if(stepper.distanceToGo() == 0){
    delay(50); // Short delay between moves
    stepper.moveTo(mm * mmSteps);
  }
  stepper.run();
}

void loop() {
  motMove(2); // Go to 2mm (based on steps/mm defined above)
  motMove(0); // Go to 0mm
}