keyboard.vhd

4*4键盘显示的4x4键盘识别与显示模块。小键盘中有0~f共16个按键

--***********************************************************
--********Filename:keyboard.vhd******************************
--********Origin date:3/15/2006******************************
--********Function:keyboard scan and LED display*************
--***********************************************************
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
library altera;
use altera.maxplus2.all;
--
--*******************************
entity keyboard is
  port
  (
     clk_4M: in std_logic;                         --系统原始时钟脉冲(假设为4M)
     key_in: in std_logic_vector(3 downto 0);      --按键输入
     clk_scan: out std_logic_vector(3 downto 0);   --扫描序列
     out_numb: out std_logic_vector(3 downto 0);   --数字输出
	 a,b,c,d,e,f,g: out std_logic;	               --数码管显示输出
     --flag_numb: out std_logic;					   --数字输出标志              
     clk_debounce: out std_logic                  --弹跳电路取样时钟脉冲
     --clk_display: out std_logic_vector(1 downto 0) --显示器扫描信号
   );
end keyboard;
--
--*********************************
architecture arc of keyboard is
component debouncing
    port(d_in: in std_logic;
         clk: in std_logic;
         d_out: out std_logic);
end component;
signal clk: std_logic;
--电路工作时钟脉冲(从4M降频而来)
signal c_keyboard: std_logic_vector(1 downto 0); 
signal c_debounce: std_logic;       
--signal c_display: std_logic_vector(1 downto 0);
signal cc: std_logic_vector(3 downto 0);
signal n: std_logic_vector(3 downto 0);
--signal fn: std_logic;
signal sel: std_logic_vector(3 downto 0);

begin

--**********************************
--connection 管脚信号连接   
out_numb<=n;
--flag_numb<=fn;
clk_debounce<=c_debounce;
--clk_display<=c_display;
c_debounce<=clk;
--
--***********************************
--scan signal generator 产生不同频率的信号
counter: block
   signal q: std_logic_vector(19 downto 0);--free counter
   signal s: std_logic_vector(1 downto 0); --00-01-10-11
   signal sel:std_logic_vector(3 downto 0);--1110-1101-1011-0111

   begin   
   process(clk_4M)
   begin
   if clk_4M'event and clk_4M='1' then
      q<=q+1;
   end if;
--The following 3 lines is used in hardware
   --c_kyeboard <= q(18 downto 17);
   --c_debounce <= q(14) 
   --c_display  <= q(18 downto 17);
--simulating to observe the results   
      c_keyboard <= q(5 downto 4);
      clk <= q(0); 
      --c_display  <= q(5 downto 4); 
  end process;
  sel<="1110" when c_keyboard = 0 else
       "1101" when c_keyboard = 1 else
       "1011" when c_keyboard = 2 else
	   "0111" when c_keyboard = 3 else
       "1111";
 clk_scan<=sel;
end block counter;
--
--************************************
--debounce program
debounce:block
begin
u1:debouncing port map
  (
    d_in => key_in(0),
    d_out => cc(0),
    clk => c_debounce
   );
u2:debouncing port map
  (
    d_in => key_in(1),
    d_out => cc(1),
    clk => c_debounce
   );
u3:debouncing port map
  (
    d_in => key_in(2),
    d_out => cc(2),
    clk => c_debounce
   );
u4:debouncing port map
  (
    d_in => key_in(3),
    d_out => cc(3),
    clk => c_debounce
   );
end block debounce;
--
--***************************************
--key decoder
key_decoder: block
  signal z: std_logic_vector(5 downto 0);   --key position
  signal yout: std_logic_vector(6 downto 0);--LED value
  begin
    process(clk)
  begin
  z <= c_keyboard&cc;
  if clk'event and clk='1' then
     case z is
            when "001110" => n <= "0000" ; yout <= "1111110";--0
            when "001101" => n <= "0001" ; yout <= "0110000";--1
 			when "001011" => n <= "0010" ; yout <= "1101101";--2
 			when "000111" => n <= "0011" ; yout <= "1111001";--3
            when "011110" => n <= "0100" ; yout <= "0110011";--4
            when "011101" => n <= "0101" ; yout <= "1011011";--5
 			when "011011" => n <= "0110" ; yout <= "1011111";--6
 			when "010111" => n <= "0111" ; yout <= "1110000";--7
			when "101110" => n <= "1000" ; yout <= "1111111";--8
            when "101101" => n <= "1001" ; yout <= "1111011";--9
 			when "101011" => n <= "1010" ; yout <= "1110111";--a
 			when "100111" => n <= "1011" ; yout <= "0011111";--b
            when "111110" => n <= "1100" ; yout <= "1001110";--c
            when "111101" => n <= "1101" ; yout <= "0111101";--d
 			when "111011" => n <= "1110" ; yout <= "1001111";--e
 			when "110111" => n <= "1111" ; yout <= "1000111";--f
            when others =>  yout <= "0000000";
     end case;
 end if;
 end process;
 a <= yout(6);  b <= yout(5);  c <= yout(4);  d <= yout(3);
 e <= yout(2);  f <= yout(1);  g <= yout(0);
 --fn <= not (n(3) and n(2) and n(1) and n(0)); --产生数字按键标志
end block key_decoder;
end arc;
--**************The end******************