说明：  步进电机控制 设计硬件电路和单片机程序，实现对四相步进电机的运动控制，包括正反向的速度控制和角度控制。 STC89C51、四位数码管、步进电机、ULN2003
(Stepper motor control circuit and single-chip hardware design process, to achieve four-phase stepper motor motion control, including the pros and cons to the speed control and point of control. STC89C51, four digital tube, Stepper Motor, ULN2003)