trafficlights.v

交通灯及其测试程序

module Trafficlights(clock,reset,red,amber,green);
input clock,reset;
output red,amber,green;
reg [1:0]red,amber,green;
parameter A0=0,A1=1,A2=2,A3=3;
reg [1:0]mpy_stata;
always@(posedge clock or reset)
begin:process
integer count;
if(reset)begin
red=2'b0;amber=2'b0;green=2'b0;end
else case(mpy_state)
A0:count=30;red[0]=1;green[1]=1;
if(posedge clock)count=count-1;
if(!count)begin green[1]=0;mpy_state=A1;end
A1:count=5;amber[1]=1;
if(!count)begin red[0]=0;amber[1]=0;mpy_state=A2;end
A2:count=40;red[1]=1;green[0]=1;
if(posedge clock)count=count-1;
if(!count)begin green[0]=0;mpy_stste=A3;end
A3:count=5;amber[0]=1;
if(posedge clock)count=count-1;
if(!count)begin red[1]=0;amber[0]=0;mpy_state=A0;end
endcase
end
endmodule