实现步进电机的S曲线启动与减速，实际项目使用(S stepper motor implementation of the curve to start and slow down, the actual use of the project)

带有S型曲线加减速的步进电机驱动程序，基于hal库，用stm32 cube mx生成工程。(With the S-curve acceleration and deceleration stepper motor driver, based on hal library, with stm32 cube mx generation project.)