keywatch.vhd

many application on kit SP-3: VGA, digital clock, counter, interface PS2....

library IEEE, unisim;
use IEEE.std_logic_1164.all;
use IEEE.NUMERIC_STD.all;
use unisim.vcomponents.all;
use work.key_Inter_pckg.all;

entity KeyWatch is --100_000
  generic(FREQ : natural := 50000 );   -- frequency of main clock (KHz)
  port(clk  : in  std_logic;     -- main clock
		rdy  : buffer  std_logic;  
		 ps2_clk  : in  std_logic;           -- keyboard clock
		 ps2_data : in  std_logic;           -- keyboard data
		 s        : out std_logic_vector(7 downto 0);  -- LED display
		 sccode  : out std_logic_vector(7 downto 0));
end keyWatch ;

architecture behave of keyWatch  is
  
  constant YES : std_logic := '1';
  constant NO  : std_logic := '0';

  signal scancode  : std_logic_vector(7 downto 0);  -- scancode from keyboard
--  signal rdy       : std_logic;         -- indicates when scancode is available
  signal s_x       : std_logic_vector(7 downto 0);  -- next state of LED segments
  signal kbd_error : std_logic;         -- error receiving scancode from keyboard

  -- LED segment activation patterns for various numbers and letters
begin

  u400 : key_interface
    generic map( FREQ  => FREQ   )
    port map(
      clk      => clk,                  -- clock for the keyboard interface
      rst      => kbd_error,            -- reset the keyboard intfc whenever there is an error receiving a scancode
      ps2_clk  => ps2_clk,              -- clock from the keyboard
      ps2_data => ps2_data,             -- serial data from the keyboard (valid on falling edge of ps2_clk)
      scancode => scancode,             -- the scancode received from the keyboard
      rdy      => rdy,                  -- indicates when a scancode from the keyboard is available
      error    => kbd_error             -- indicates an error in receiving a scancode from the keyboard
      );
 
  -- update the LED display
  process(clk)
  begin
	  if rising_edge(clk) then			
			if rdy = YES then
			  s <= s_x;                       -- update the display each time a scancode is received		
				sccode <= scancode;
			end if;
		 end if;
  end process;
end behave;