说明：  步进电机驱动器，使单片机输出 CP-，CW-，和FRE-，信号给步进电机驱动， 高速从500Hz可以加速10490Hz，低速从102Hz可以加速500Hz
(Stepper motor drives, so that single-chip output CP-, CW-, and FRE-, signals to the stepper motor-driven, high-speed 500Hz can accelerate from 10490Hz, low-speed can accelerate 500Hz from 102Hz)