js.vhd

基本交通系统,实现城市交通路口的模拟仿真

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity js is
port(clk:in std_logic;
led1,led10a:out std_logic_vector(0 to 3));
end js;

architecture stl of js is
signal ledd1:std_logic_vector(0 to 3) :="1001";
signal ledd10:std_logic_vector(0 to 3) :="0011";
begin
a1:process(clk)
begin


if(clk='1' and clk'event)then 
 if(ledd1="0000")then
   ledd1<="1001";
 else ledd1<=ledd1-1;
 end if;
end if;
 end process a1;

a2:process(clk,ledd1)
begin
if(clk='1' and clk'event)then 
 if(ledd1="0000")then
 if(ledd10="0000")then
    ledd10<="0011";
 else ledd10<=ledd10-1;
 end if;
 end if;
end if;
end process a2;
led1<=ledd1;led10a<=ledd10;
end stl;