traffic1.vhd

msttr是用vhdl语言开发的一个交通灯程序

library ieee;
use ieee.std_logic_1164.all;
entity traffic1 is
  port(clk,rst,en:in std_logic;
       R1,G1,Y1:out std_logic;

       r2,g2,y2:out std_logic);
end ;
architecture light of traffic1 is

begin
process(clk,rst)
variable count1:integer range 0 to 31;
begin
if (en=1) then
cycle:for count1 in 0 to 31 loop
	if rst='1' then R1<='0'; G1<='0'; Y1<='0';r2<='0';g2<='0';y2<='0';
	end if;
case count1 is
	when 0 to 14  =>G1<='1';Y1<='0';R1<='0';r2<='1';g2<='0';y2<='0';
	when 15 to 17 =>G1<='0';Y1<='1';R1<='0';r2<='0';g2<='0';y2<='0';
	when 18 to 20 =>R1<='1';Y1<='0';G1<='0';r2<='0';y2<='1';
	when 21 to 30 =>y2<='0';g2<='1';
end case;
end for;
end if;
end ;