//我们用索引的方式输出，比如正转，元素由0到8这样的循环，反转则由8到0的循环//程序中我们保存索引号，比如上次转在第4元素停下，则下次的正转由5开始向后计数，反转则由3开始向前计数这样，电机的转角度就会很准确

-//We use the output index approach, such as being transferred, the element from the 0-8 this cycle, reverse cycle from 8-0// program, we save the index number, such as the last turn at the 4th stop element , then the next time the forward counting backwards from 5 start, reverse counting from 3 start to move this way, the motor will be very accurate to the point of