#include <Stepper.h>

// Define number of steps per revolution:
const int stepsPerRevolution = 200;
// Initialize the stepper library on pins 8 through 11:
Stepper myStepper = Stepper(stepsPerRevolution, 8, 9, 10, 11);
void setup() {
  // Set the motor speed (RPMs):
  myStepper.setSpeed(100);
}
void loop() {
  // Step one revolution in one direction:
  myStepper.step(200);
  delay(2000);
  // Step on revolution in the other direction:
  myStepper.step(-200);
  delay(2000);
}