ledshow.vhd

用vhdl实现ps2鼠标的源程序

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity ledshow is
    Port ( clk : in std_logic;
           reset : in std_logic;
           xdot : in std_logic_vector(8 downto 0);
           ydot : in std_logic_vector(8 downto 0);
           ledA1 : out std_logic;
           ledA2 : out std_logic;
           ledA3 : out std_logic;
           ledA4 : out std_logic;
           leddata : out std_logic_vector(6 downto 0));
end ledshow;

architecture Behavioral of ledshow is

component segdecode 
    Port ( datain : in std_logic_vector(3 downto 0);
           dataout : out std_logic_vector(6 downto 0)
			  );
end component;

signal sel : std_logic_vector(1 downto 0);
signal data : std_logic_vector(3 downto 0);
signal dataout : std_logic_vector(6 downto 0);

begin
  selcount: process (reset,clk)
  begin
    if (reset='0') then
		sel <= "00";
	 elsif (clk'event and clk='1') then
	   sel <= sel+'1';
	 end if;
  end process;

  selchoice: process (sel,xdot,ydot)
  begin
    ledA1 <= '0';
	 ledA2 <= '0';
	 ledA3 <= '0';
	 ledA4 <= '0';
    case sel is
	   when "00" =>
		  ledA1 <= '1';
		  data <= xdot(3 downto 0);
		when "01" =>
		  ledA2 <= '1';
		  data <= xdot(7 downto 4);
		when "10" =>
		  ledA3 <= '1';
		  data <= ydot(3 downto 0);
		when "11" =>
		  ledA4 <= '1';
		  data <= ydot(7 downto 4);
		when others => data <= "0000";
	 end case;
  end process;

  decode: segdecode Port map(
           datain => data,
           dataout => dataout
			  );

  leddata <= dataout;

end Behavioral;