一种串口+按键控制步进电机的c语言程序，可以按加速，减速键控制速度，按逆时针/顺时针键控制转向，按暂停键使步进电机暂停。-A kind of serial+ key control stepper motor c language program, can be speed up, slow down keys to control speed, according to counter-clockwise/clockwise shift key control, stepping motor