设计一个十字路口的交通灯控制电路，要求东西方向车道和南北方向车道两条交叉道路上的车辆交替运行，每次通行时间都设为45秒。时间可设置修改。-Designed a crossroads of traffic lights control circuit, require lane east-west direction and north-south direction cross the two lane road on the turn of the vehicle is running, each opening hours are set to 45 seconds. Time can be set up to amend.