int BUTTON = 5;
int LED = 6;
int M1_ENA = 7;
int M1_DIR = 8;
int M1_STEP = 9;

int queuedSteps;
int prevButtonState;

void setup() {
  pinMode(M1_ENA, OUTPUT);
  pinMode(M1_DIR, OUTPUT);
  pinMode(M1_STEP, OUTPUT);
  pinMode(LED, OUTPUT);
  pinMode(BUTTON, INPUT_PULLUP);

  prevButtonState = HIGH;
}

void loop() {
  int buttonState = digitalRead(BUTTON);

  // when the button is released, turn the light on
  // and add some steps to the queue
  if (buttonState == HIGH && prevButtonState == LOW) {
    queuedSteps += 25;
    digitalWrite(LED, HIGH);
  }

  if (steps > 0) {
    // we have steps in the queue, perform one
    digitalWrite(M1_ENA, LOW);
    digitalWrite(M1_DIR, HIGH);
    digitalWrite(M1_STEP, HIGH);
    digitalWrite(M1_STEP, LOW);
    queuedSteps--;
  }
  else {
    // queue is empty, turn the light off
    digitalWrite(LED, LOW);
  }

  prevButtonState = buttonState;

  // sleep for a bit
  delay(50);
}