电梯停在一楼时，接受到请求信号c_d3、c_d2、c_u4和d6，并把请求信号写入相应的寄存器。led显示电梯所在楼层；led_d、led-c_u和led_c_d显示用户的请求。-When the elevator stopped on the first floor, received the request signal c_d3, c_d2, c_u4 and d6, and the write request signal corresponding register. led disp