十字路*通灯的变化规律要求：

（1） 南北路口的绿灯、东西路口的红灯同时亮30秒左右。

（2） 南北路口的黄灯闪烁若干次，同时东西路口的红灯继续亮。

（3） 南北路口的红灯、东西路口的绿灯同时亮30秒左右。

（4） 南北路口的红灯继续亮、同时东西路口的黄灯亮闪烁若干次。

（5） 转(1)重复。

通过连接的 七段数码管动态显示绿灯剩余时间-Changes of traffic lights crossroads requirements: (1) North-South crossing the green light, red light intersection at the same time something light about 30 seconds. (2) North and South junctions yellow light flashes several times while crossing the red light continues to light things. (3) North-South crossing the red light, green light while crossing something light about 30 seconds. (4) North-South crossing red lights continue to shine, while the yellow light is flashing something a number of junctions. (5) change (1) repeat. By connecting the seven-segment digital tube remaining time dynamic display of green light