Verilog_traffic

代码说明：

  若农场路无车辆，则在高速路保持绿灯。在探测农场路有车辆，高速路上的交通灯应由绿到黄，再到红，并允许农场路方向灯变绿，绿灯亮一段时间，由绿变黄再到红。(If there is no vehicle on the farm road, keep the green light on the highway. There are vehicles on the farm road, the traffic lights on the high speed road should be green to yellow, and then red, and allow the farm road lights to turn green, the green light for a period of time, from green to yellow, then to red.)