clock.vhd

用VHDL语言编写的时钟显示的源程序代码

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity clock is
   port(clk,clk2:in std_logic;
        show:out std_logic_vector(6 downto 0);
        decode:buffer std_logic_vector(2 downto 0)
        );
end clock;
architecture clock_display of clock is
component cnt24 is
	port( hh,hl : buffer std_logic_vector (3 downto 0);
      	  clk : in std_logic 
	);
	 end component ;
component cnt60 is
	port(ch,cl : buffer std_logic_vector (3 downto 0);
      	 clk : in std_logic ;
		 carry: buffer std_logic   --?? buffer
	); 
	end component ;
signal hourh,hourl,minh,minl,sech,secl: std_logic_vector( 3 downto 0);
signal c0:std_logic;
signal tempt: std_logic_vector (3 downto 0);
signal c1,c2: std_logic ;
begin
  	sec: cnt60 port map (sech,secl,clk,c1);
	min: cnt60 port map (minh,minl,c1,c2);
	hor: cnt24 port map (hourh,hourl,c2);
  process(clk)
  begin
	if clk'event and clk='1' then 
		c0 <= not c0;
	end if;
  end process;
  process(clk2)
  begin 
  	if clk2'event and clk2 = '1' then
		case decode is
		when "110" => tempt <=secl; --hourh;
		when "111" => tempt <=sech; --hourl;
		when "000" => tempt <= "1111";
		when "001" => tempt <=minl; --minh;
		when "010" => tempt <=minh; --minl;
		when "011" => tempt <= "1111";
		when "100" => tempt <= hourl;--sech;
		when "101" => tempt <=hourh; --secl;
		end case;--XUN HUAN LED
		decode <= decode+1;		
	end if;
  end process;
  process(clk2)
  begin 
  	if clk2'event and clk2 = '1' then
		case tempt is
		when "0000" => show <= "1111110";	--led 0  --Ox7E
		when "0001" => show <= "0110000";	--led 1  --Ox30
		when "0010" => show <= "1101101";	--led 2  --Ox6D
		when "0011" => show <= "1111001";	--led 3  --Ox79
		when "0100" => show <= "0110011";	--led 4  --Ox33
		when "0101" => show <= "1011011";	--led 5  --Ox5B
		when "0110" => show <= "1011111";	--led 6  --Ox5F
		when "0111" => show <= "1110000";	--led 7  --Ox70
		when "1000" => show <= "1111111";	--led 8  --Ox7F
		when "1001" => show <= "1111011";	--led 9  --Ox7B
		when "1111" => show <= "0000001";	--led -  --Ox01
		when others => show <= "1111110";	--led     --Ox7e
		end case ;
	end if;
  end process;
 end architecture clock_display;