我有个实验基于FPGA的键盘扫描的设计我现在程序有了

但是不知道要定义那几个模块

求高手帮我做一下Quartus仿真设计

程序后贴
 
--* 4x4标准键盘板读取并点亮开发板上相应led
--* Filename: keyboard4_4
--* 扫描键盘，译码并点亮开发板上相应led
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity keyboard4_4 is
port(
rst : in std_logic;
clk : in std_logic;
keyin : in std_logic_vector(3 downto 0);
scan : out std_logic_vector(3 downto 0);
leds : out std_logic_vector(3 downto 0)
);
end keyboard4_4;

architecture keyboard4_4_arch of keyboard4_4 is

signal clkfrq : std_logic;

signal cntscn : std_logic_vector(1 downto 0);
signal scnlin : std_logic_vector(3 downto 0);
signal cntfrq : std_logic_vector(14 downto 0);
--signal cntfrq : std_logic_vector(3 downto 0);
signal lednum : std_logic_vector(7 downto 0);
begin
process(rst,clk, clkfrq)
begin
if rst = '0' then
clkfrq <= '0';
cntfrq <= (others=>'0');
elsif clk'event and clk = '1' then
if cntfrq = "110000110101000" then 
if cntfrq = "1111" then 
cntfrq <= (others => '0');
clkfrq <= not clkfrq;
else
cntfrq <= cntfrq + 1;
end if;
end if;
end process;

process(rst,clkfrq)

begin

if rst = '0' then

cntscn <= "00";



elsif clkfrq'event and clkfrq = '1' then



if cntscn = "11" then



cntscn <= "00";



else



cntscn <= cntscn+1;



end if;



case cntscn is



when "00" => scnlin <= "0001";



when "01" => scnlin <= "0010";



when "10" => scnlin <= "0100";



when "11" => scnlin <= "1000";



when others => null;



end case;



end if; 



end process; 



-- 根据按键点亮相应的leds



process(rst, clkfrq)



begin



if(rst = '0' ) then



leds <= "1111";



elsif clkfrq'event and clkfrq = '0' then



case lednum is



when "00010001" =>


leds <= "0000";



when "00010010" =>



leds <= "0001";



when "00010100" =>



leds <= "0010";



when "00011000" =>



leds <= "0011";



when "00100001" =>



leds <= "0100";



when "00100010" =>



leds <= "0101";



when "00100100" =>



leds <= "0110";



when "00101000" =>



leds <= "0111";






when "01000001" =>



leds <= "1000";



when "01000010" =>



leds <= "1001";



when "01000100" =>



leds <= "1010";



when "01001000" =>



leds <= "1011"; 






when "10000001" =>



leds <= "1100";



when "10000010" =>



leds <= "1101";



when "10000100" =>



leds <= "1110";



when "10001000" =>



leds <= "1111"; 






;



when others => null;

end case;



end if;



end process;






scan <= scnlin;



lednum <= scnlin&keyin