/*---------------------------------------*\
  | Simple direct drive of Bipolar Stepper  |
  \*---------------------------------------*/

// pins connected
#define Ap 10  // A+ line
#define Am 11  // A- line
#define Bp 9   //  .
#define Bm 8   //  .

void setup() {
  // set output
  pinMode(Ap, OUTPUT);  pinMode(Am, OUTPUT);
  pinMode(Bp, OUTPUT);  pinMode(Bm, OUTPUT);
}

int I = 0 ;
void loop() {
  // This is Wave Fullstep motion - only one coil energized at a time
  if ( I++ < 25 ) { // stop after 25*4 steps (=100) - quarter turn with gearRatio "2:1"
    delay(100);
    digitalWrite(Ap, HIGH); digitalWrite(Am, LOW) ; digitalWrite(Bp, LOW) ; digitalWrite(Bm, LOW) ;
    delay(100);
    digitalWrite(Ap, LOW) ; digitalWrite(Am, LOW) ; digitalWrite(Bp, HIGH); digitalWrite(Bm, LOW) ;
    delay(100);
    digitalWrite(Ap, LOW) ; digitalWrite(Am, HIGH); digitalWrite(Bp, LOW) ; digitalWrite(Bm, LOW) ;
    delay(100);
    digitalWrite(Ap, LOW) ; digitalWrite(Am, LOW) ; digitalWrite(Bp, LOW) ; digitalWrite(Bm, HIGH);
  } else while (1);
}