#define dirPin 2
#define stepPin 3
#define stepPerRev 200

void setup() {
  pinMode(stepPin, OUTPUT);
  pinMode(dirPin, OUTPUT);
}

void loop() { // direction and 1/2 pulsewidth
  bool dir = random(2); // direction is HIGH = CW, LOW = CC
  int del = random(500, 2000); // 500 = quick, 2000 = slow
  digitalWrite(dirPin, dir); // set direction
  for (int i = 0; i < stepPerRev; i++) { // make one pulse
    digitalWrite(stepPin, HIGH);
    delayMicroseconds(del);
    digitalWrite(stepPin, LOW);
    delayMicroseconds(del);
  }
  delay(500);
}