counter60.vhd

实现一个简单的电子钟

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

entity counter60 is
port ( cp:in std_logic;
       bin:out std_logic_vector(5 downto 0);
       s,clr,ec:in std_logic;
       cy60:out std_logic
      );

end counter60;

architecture a of counter60 is

 signal q:std_logic_vector(5 downto 0);
signal rst,dly:std_logic;

begin
process(cp,rst)
        begin
    if (rst='1')  then
         q<="000000";


    elsif cp'event and cp='1' then
       dly<=q(5);
        if ec='1'  then 
            q<=q+1;
          end if;
          end if;
         end process;
         cy60<=not q(5) and dly ;
         rst<='1'when q=60 or clr='1'else 
              '0';
  
         bin<=q when s='1'else "000000";
        
         end a;