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// testing a stepper motor with a Pololu A4988 driver board or equivalent

// this version uses millis() to manage timing rather than delay()
// and the movement is determined by a pair of momentary push switches
// press one and it turns CW, press the other and it turns CCW

byte directionPin = 9;
byte stepPin = 8;

byte buttonCWpin = 10;
byte buttonCCWpin = 11;

boolean buttonCWpressed = false;
boolean buttonCCWpressed = false;

byte ledPin = 13;

unsigned long curMillis;
unsigned long prevStepMillis = 0;
unsigned long millisBetweenSteps = 25; // milliseconds

void setup() { 

  Serial.begin(9600);
  Serial.println("Starting Stepper Demo with millis()");

  pinMode(directionPin, OUTPUT);
  pinMode(stepPin, OUTPUT);
  pinMode(ledPin, OUTPUT);
  
  pinMode(buttonCWpin, INPUT_PULLUP);
  pinMode(buttonCCWpin, INPUT_PULLUP);
  
}

void loop() { 
	
	curMillis = millis();
	readButtons();
	actOnButtons();
	
}

void readButtons() {
	
	buttonCCWpressed = false;
	buttonCWpressed = false;
	
	if (digitalRead(buttonCWpin) == LOW) {
		buttonCWpressed = true;
	}
	if (digitalRead(buttonCCWpin) == LOW) {
		buttonCCWpressed = true;
	}
}

void actOnButtons() {
	if (buttonCWpressed == true) {
		digitalWrite(directionPin, LOW);
		singleStep();
	}
	if (buttonCCWpressed == true) {
		digitalWrite(directionPin, HIGH);
		singleStep();
	}
}

void singleStep() {
	if (curMillis - prevStepMillis >= millisBetweenSteps) {
		prevStepMillis += millisBetweenSteps;
		digitalWrite(stepPin, HIGH);
		digitalWrite(stepPin, LOW);
	}
}