按一下奇數跑(由左往右) 再按一下(由右往左) 每次都-2

 int led_pin[] = {2, 3, 4, 5, 6, 7, 8, 9};

int j = -2;

int direct = 0;

int btn_pin = 10;

int val = 1;

int r=9;

void setup()

{

  Serial.begin(9600);

  pinMode(btn_pin, INPUT);

  for (int i = 0; i < 8; i++)

  {

    pinMode(led_pin[i], OUTPUT);

  }

}

void loop()

{

  for (int k = 0; k < 8; k++)

  {

    digitalWrite(led_pin[k], LOW);

  }

  val = digitalRead(btn_pin);//按下去沒反應可能電位有問題，用邏輯探測棒debug

  if (val == 0)

  {

    val = digitalRead(btn_pin);

    delay(1000);

    while (digitalRead(btn_pin) == LOW);

    direct = !direct;

  }

  if (direct == 0)//由左往右跑每次+2

  {

     if (j == 6)

      j = 0;

    else

      j = j + 2;

      // 0 1 2 3 4 5 6 7

    if(j==1) j=2;//如果奇數切過來是1就變偶數2(index)

    if(j==3) j=4;//如果奇數切過來是3就變偶數4(index)

    if(j==5) j=6;//如果奇數切過來是5就變偶數6(index)

    if(j==7) j=0;//如果奇數切過來是7就變偶數0(index)

    digitalWrite(led_pin[j], HIGH);

    delay(1000);

  }

  else

  {

     if (j == 1)//由右往左跑，每次-2

      j = 7;

    else

      j = j - 2;

      // 0 1 2 3 4 5 6 7

    if(j==0) j=7;//如果偶數切過來是0就變奇數7(index)

    if(j==2) j=1;//如果偶數切過來是2就變奇數1(index)

    if(j==4) j=3;//如果偶數切過來是4就變奇數3(index)

    if(j==6) j=5;//如果偶數切過來是6就變奇數5(index)

    digitalWrite(led_pin[j], HIGH);

    delay(1000);

  }

}