m6_1scan.vhd

来自「ＦＰＧＡ数字钟的设计」· VHDL 代码 · 共 39 行

library ieee; 
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity m6_1scan is
port(clkscan,reset:in std_logic;
  in1,in2,in3,in4,in5,in6: in std_logic_vector(3 downto 0);
  data:out std_logic_vector(3 downto 0);
  sel: out std_logic_vector(2 downto 0)); 
end m6_1scan;
architecture t1 of m6_1scan is
signal count: std_logic_vector(2 downto 0);
begin
process(clkscan,reset)   
  begin
    if reset='1' then
      count<="000";
    elsif (clkscan'event and clkscan='1') then
        if count="101" then
          count<="000";
        else
          count<=count+1; 
        end if;
    end if;
  end process;
process(count)                 
begin  
case count is
    when "000"=>data<=in1;
    when "001"=>data<=in2;
    when "010"=>data<=in3;
    when "011"=>data<=in4;
    when "100"=>data<=in5;
    when others=>data<=in6;
  end case;
  end process;
  sel<=count;
end t1;