1:利用单片机的定时器产生秒信号，控制十字路口的红绿黄灯交替点亮和熄灭，

2:能够用4只LED数码管显示十字路口两个方向的剩余时间。要求能用按键设置两个方向的通行时间（绿灯点亮的时间）和暂缓通行时间（黄灯点亮的时间）。

3:系统的工作应符合一般交通灯控制的要求。-1: SCM the timer generates seconds signal alternately turned on and off, control the red, green and yellow of the crossroads,

2: 4 LED digital tube display the remaining time of the crossroads of two directions. Requirements can use the button to set the two directions of travel time (green light time) and suspend the passage of time (yellow light time).

3: The system shall conform to the requirements of the general traffic light control.