show.vhd

1、正常的计时功能：即具有二十四小时计时功能 2、正常的显示功能 3、正常的调时功能 4、闹钟定时功能 5、整点报时功能

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity show is
 port(hs1,ms1,ss1:in std_logic_vector(7 downto 4);
      hs2,ms2,ss2:in std_logic_vector(3 downto 0);
      bh1,bm1,bs1:in std_logic_vector(7 downto 4);
      bh2,bm2,bs2:in std_logic_vector(3 downto 0);
      h0,h1,m0,m1,s0,s1:      out std_logic_vector(3 downto 0);
      reset,sel:              in std_logic);
end show;
architecture showx of show is
 begin
 cm:process(reset,sel)
  begin
  if reset='1' then
     h0<="0000";
     h1<="0000";
     m0<="0000";
     m1<="0000";
     s0<="0000";
     s1<="0000";
  elsif reset='0' then
   if sel='1' then
    h0<=hs1;
    h1<=hs2;
    m0<=ms1;
    m1<=ms2;
    s0<=ss1;
    s1<=ss2;
   elsif sel='0' then
    h0<=bh1;
    h1<=bh2;
    m0<=bm1;
    m1<=bm2;
    s0<=bs1;
    s1<=bs2;
   end if;
  end if;
 end process cm;    
end showx;