fd.vhd

这是一个键盘防抖动的C程序。该防抖动程序采用计数器型

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity fd is
 port(clk:in std_logic;
      key:in std_logic;
      keyout:out std_logic);
 end fd;

architecture rt of fd is
signal q:std_logic_vector(24 downto 0);
signal jsq:integer range 0 to 60;
begin
 process(clk)
  begin
   if(clk'event and clk='1')then
     if(q=20000000)then
        q<="0000000000000000000000000";
     else
        q<=q+"0000000000000000000000001";
     end if;
    end if;
   end process;
process(q)
 begin
  if(q(14)'event and  q(14)='1')then
    if(key='1')then
      if(jsq=35)then
        jsq<=jsq;
      else
        jsq<=jsq+1;
      end if;
    else
     jsq<=0;
   end if;
  end if;
if(jsq=35)then
  keyout<='1';
 else
  keyout<='0';
end if;
 end process;
 
end rt;