在开发板上模拟4层电梯运行。使用键盘控制电梯的运行，使用流水灯显示电梯运行方向，8段数码管显示电梯当前的位置。-4 layer board in the development of simulated elevator operation. Use the keyboard to control the operation of the lift, use water to run lights show the direction of the lift, 8 digital display lift the current position.