const byte IN1 = 8; // output for L293d
const byte IN2 = 9; // output for L293d

void setup()
{
  Serial.begin(115200);

  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);

  digitalWrite (IN1, LOW);
  digitalWrite (IN2, LOW);
}

void oneStep()
{
  static boolean polarity = true;

  digitalWrite(polarity ? IN1 : IN2, HIGH);

  delay(150);

  digitalWrite (IN1, LOW);
  digitalWrite (IN2, LOW);

  polarity = !polarity;
}

unsigned long previousStep;

void loop()
{
	if (millis() - previousStep < 1777) return;

	previousStep += 1000;

	oneStep();
}