交通灯电路，南北方向和东西方向分别按绿灯、黄灯、左拐灯、黄灯、红灯的顺序两灭，数码管显示相应的灯亮的时间的倒计时。已通过编译和仿真。-Traffic light circuit, north-south direction and east-west direction respectively green, yellow light, left light, yellow light, red light destroy the order of two, a digital LED disp