51单片机控制5804驱动芯片驱动步进电机，速度值通过spi接口（软实现）通讯存储在外部eeprom上，断电不丢失。-51 SCM control 5804 driver chip to drive a stepper motor, the speed value is through the spi interface (soft implementation) communication is stored in the external eeprom, the power is not lost.