说明：  利用新华龙公司生产的C8051F020单片机驱动四相步进电机，可实现单拍、双拍、四相八拍的正转反转即变速功能。所需驱动电路由达林顿三极管组成
(The use of single-chip four-phase stepper motor drive can achieve single-shot two-shot film of the eight four-phase reverse switch that is required for variable-speed function driver circuit formed by a Darlington transistor)