Stepping.ino

const int AIN1 = 12;
const int BIN1 = 11;
const int BTN = 10;

void setupPin(int pin) {
  pinMode(pin, OUTPUT);
}

void setup() {
  // put your setup code here, to run once:
  setupPin(AIN1);
  setupPin(BIN1);
  pinMode(AIN1, OUTPUT);
  pinMode(BIN1, OUTPUT);
  pinMode(BTN, INPUT_PULLUP);
}

void writeSignal(int a, int b) {
  digitalWrite(AIN1, a);
  digitalWrite(BIN1, b);
}

const int STEPS[] = {
  HIGH, HIGH,
  LOW, HIGH,
  LOW, LOW,
  HIGH, LOW
};

int currentStep = 2;

void writeStep() {
  digitalWrite(AIN1, STEPS[currentStep * 2]);
  digitalWrite(BIN1, STEPS[currentStep * 2 + 1]);
}

// 7.5°時計回り
void rotate() {
  if (currentStep >= 3)
    currentStep = 0;
  else
    currentStep++;

  writeStep();
}

// 7.5°反時計回り
void rotateReverse() {
  if (currentStep <= 0)
    currentStep = 3;
  else
    currentStep--;

  writeStep();
}

bool reverse = false;

void loop() {
  if (digitalRead(BTN) == LOW) {
    for (int i = 0; i < 12; i++) {
      if (reverse) rotateReverse();
      else rotate();
      delay(20);
    }

    delay(500);
    reverse = !reverse;
  }
}