设计一个简单的交通灯控制器，他有5个状态，每个状态都具有可独立编程确定的时间参数（parameter），假设时钟频率为50Hz（如果仿真时间太长可以做适当的比例修改）。
路口交通灯示意图
设计代码
`timescale 1ns / 1ps
module Test1530(clk,reset,red1,yellow1,green1,red2,yellow2,green2);
input clk;
input reset;
output red1,yellow1,green1;
reg red1,yellow1,green1;
output red2,yellow2,green2;
reg red2,yellow2,green2;
reg [11:0] count;
parameter Y1Y2=0,R1Y2=1,G1R2=2,Y1R2=3,R1G2=4;
parameter timeR1Y2=250，timeG1R2,2500,timeY1R2=250,timeR1G2=2250;
reg [2:0] state;
/
always @(posedge clk)
if(reset)
begin
count<=0;
state<=Y1Y2;
red1<=0;yellow1<=1;green1<=0;
red2<=0;yellow2<=1;green2<=0;
end
else
case(state)
Y1Y2:begin
state<=R1Y2;
count<=1;
end
R1Y2:begin
if(count= =timeR1Y2)
begin
state<=G1R2;
red1=0;yellow1<=0;green1<=1;
red2=1;yellow2<=0;green2<=0;
count<=1;
end
else
begin
state<=R1Y2;
red1=1;yellow1<=0;green1<=0;
red2=0;yellow2<=1;green2<=0;
count<=count+1;
end
end
G1R2:begin
if(count= =timeG1R2)
begin
state<=Y1R2;
red1=0;yellow1<=1;green1<=0;
red2=1;yellow2<=0;green2<=0;
count<=1;
end
else
begin
state<=G1R2;
red1=0;yellow1<=0;green1<=1;
red2=1;yellow2<=0;green2<=0;
count<=count+1;
end
end
Y1R2:begin
if(count= =timeY1R2)
begin
state<=R1G2;
red1=1;yellow1<=0;green1<=0;
red2=0;yellow2<=0;green2<=1;
count<=1;
end
else
begin
state<=Y1R2;
red1=0;yellow1<=1;green1<=0;
red2=1;yellow2<=0;green2<=0;
count<=count+1;
end
end
R1G2:begin
if(count= =timeR1G2)
begin
state<=R1Y2;
red1=1;yellow1<=0;green1<=0;
red2=1;yellow2<=0;green2<=0;
count<=1;
end
else
begin
state<=R1G2;
red1=1;yellow1<=0;green1<=0;
red2=0;yellow2<=0;green2<=1;
count<=count+1;
end
end
default:state<=Y1Y2;
endcase
endmodule
测试代码
`timescale 1ns / 1ps
module Test1620;
reg clk;
reg reset;
wire red1,yellow1,green1,red2,yellow2,green2;
always begin
#10 clk=1;
#10 clk=0;
end
initial begin
clk=0;
reset=1;
#10000;
reset=0;
end
Test1530 x1(.clk(clk),
.reset(reset),
.red1(red1),
.yellow1(yellow1),
.green1(green1),
.red2(red2),
.yellow2(yellow2),
.green2(green2));
endmodule
仿真波形
