Subversion Repositories System09

--===========================================================================--

--                                                                           --

--                    LED Flasher                                            --

--                                                                           --

--===========================================================================--

--

--  File name      : flasher.vhd

--

--  Entity name    : flasher

--

--  Purpose        : Implements a long counter used to flash a LED

--                   to indicate code has loaded correctly

--

--  Dependencies   : ieee.std_logic_1164

--                   ieee.numeric_std

--                   ieee.std_logic_unsigned

--

--  Author         : John E. Kent

--

--  Email          : dilbert57@opencores.org      

--

--  Web            : http://opencores.org/project,system09

--

--

--  Copyright (C) 2010 John Kent

--

--  This program is free software: you can redistribute it and/or modify

--  it under the terms of the GNU General Public License as published by

--  the Free Software Foundation, either version 3 of the License, or

--  (at your option) any later version.

--

--  This program is distributed in the hope that it will be useful,

--  but WITHOUT ANY WARRANTY; without even the implied warranty of

--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

--  GNU General Public License for more details.

--

--  You should have received a copy of the GNU General Public License

--  along with this program.  If not, see <http://www.gnu.org/licenses/>.

--

--===========================================================================--

--                                                                           --

--                              Revision  History                            --

--                                                                           --

--===========================================================================--

--

-- Version Author        Date         Changes

--

-- 0.1     John Kent     2010-08-28   Made separate module

--

library ieee;

  use ieee.std_logic_1164.all;

  use ieee.numeric_std.all;

  use ieee.std_logic_unsigned.all;

--library unisim;

--  use unisim.vcomponents.all;

-----------------------------------------------------------------------

--                    Entity for B3_SRAM                             --

-----------------------------------------------------------------------

entity flasher is

  port (

    clk      : in  std_logic;           -- Clock input

    rst      : in  std_logic;           -- Reset input (active high)

    LED      : out Std_Logic            -- LED output        

  );

end flasher;

--================== End of entity ==============================--

-------------------------------------------------------------------------------

-- Architecture for Flasher

-------------------------------------------------------------------------------

architecture rtl of  flasher is

-- Flashing LED test signals

signal countL       : std_logic_vector(23 downto 0);

begin

--

-- LED Flasher to indicate code has loaded

--

my_LED_Flasher : process (clk, rst, CountL )

begin

  if falling_edge(clk) then

    if rst = '1' then

      countL <= (others=>'0');

    else

      countL <= countL + 1;

    end if;

  end if;

  LED <= countL(23);

end process;

end rtl;