Big Easy Driver + Arduino

#define CLOCKWISE LOW
#define COUNTERCLOCKWISE HIGH

void stepperSteps( long n ) {
  digitalWrite( DIR_PIN, n < 0 ? COUNTERCLOCKWISE : CLOCKWISE );
  digitalWrite( ENABLE_PIN, LOW );
  n = abs( n );
  for( ; n > 0; n-- ) {
    PORTB |= _BV(PINB1); // WAY faster than digitalWrite
    delayMicroseconds( 50 );
    PORTB &= ~_BV(PINB1);
    delayMicroseconds( 50 );
  }
  digitalWrite( ENABLE_PIN, HIGH );
}