(1) 能显示十字路口东西、南北两个方向的红、黄、绿的指示状态；

• 用两组红、黄、绿三色灯作为两个方向的红、黄、绿灯，能实现正常的倒计时功能；

• 用两组数码管作为东西和南北方向的到计时显示，显示时间为红灯55秒、绿灯50秒、黄灯5秒；

*(2) 按S1键后，能实现特殊状态功能:

• 显示到计时的两组数码管闪烁；

• 计数器停止计数并保持在原来的状态；

• 东西、南北、路口均显示红灯状态；

• 特殊状态解除后能继续计数。

(3) 能实现总体清零功能按下SB键后，系统实现总清零，计数器由初始状态计数，对应状态的指示灯亮；

(4) 用VHDL语言设计符合上述功能要求的交通灯控制器，并用层次化设计方法设计该电路；

(5)控制器、置数器的功能用功能仿真的方法验证，可通过有关波形确认电路设计是否正确；

*(6)完成电路全部设计后，通过系统实验箱下载验证设计课题的正确性。

-(1) to show intersections east and west in both directions of the red, yellow, green indicates the state

•　Use two sets of red, yellow, and green lights as the two directions of red, yellow, green, countdown to achieve normal function

•　Digital control with two north-south direction as to the things and time display, time display a red light 55 seconds, 50 seconds green, yellow 5 seconds

* (2) Press the S1 key, to achieve a special state function:

•　Display to the timing of the two sets of digital flash

•　The counter stops counting and remains in its original state

•　east and west, crossing all red light status

•　Special lifting of the state can continue to count.

(3) to achieve the overall SB Clear function key pressed, the system achieved a total cleared, the counter counts from the initial state, the corresponding status indicator light

(4) using VHDL language design meets the functional requirements of the traffic light co