这是基于51单片机的四层电梯系统的设计，用到4个直流电机和2个步进电机，还有8255A用于扩展IO口，可以正常运行停止。-This is by design of the four-story elevator 51 microcontroller-based system, used four DC motors and two stepper motors, and 8255A for expansion IO port, you can stop running.