//***************************************************// File Name: tb_traffic_light_controller.v//      Date: September 29,2008//    author: yilong.you//            yilong.you@stu.xjtu.edu.cn   //**************************************************/`timescale 1ns/1nsmodule tb_traffic_light_controller;    reg clk,reset;    wire[1:0] light_color;        traffic_light_controller h1(.clk(clk),.reset(reset),.light_color(light_color));      always #1 clk=~clk;    initial begin       clk=0;             reset=1;       #2 reset=0;       #100$stop;        end    always@(negedge clk)begin       $display("At time %t:light_color=%b",$time,light_color); endendmodule