int hallSensorPin = 9;
int hallSensorPin2 = 10;

# define dirPin   2
# define stepPin  3
# define pwrOff   4

# define STEP_PERIOD  400

void setup() {
  Serial.begin(115200);  
  Serial.println("step thing happening!");

  pinMode(stepPin, OUTPUT);
  pinMode(dirPin, OUTPUT);
  pinMode(pwrOff, OUTPUT);

  pinMode(hallSensorPin, INPUT);

  digitalWrite(dirPin, HIGH);

//  digitalWrite(stepPin, HIGH);
//  for (; ; );
}

static unsigned char doStep = 0;
static unsigned char phase;

void loop() {
   
  static unsigned char doStep = 0;
  static unsigned char phase;
  static unsigned long lastStep;

// swtich to micros for stepping for real
//  unsigned long now = micros();

// use millis for development
  unsigned long now = millis();

  if (now - lastStep >= STEP_PERIOD) {
    if (doStep) {
      lastStep = now;

      digitalWrite(pwrOff, LOW); 

      if (phase & 1)
        digitalWrite(stepPin, LOW);
      else
        digitalWrite(stepPin, HIGH);

      phase++;
    }
    else {
      digitalWrite(pwrOff, HIGH);
      digitalWrite(stepPin, LOW);
    }

    doStep = digitalRead(hallSensorPin);
  }

/* 
  Serial.print(" do step ");
  Serial.print(doStep);
  Serial.print(" phase ");
  Serial.println(phase);
  
  delay(100);
*/
}