-------------------------------------------------------------------------------
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-------------------------------------------------------------------------------
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--
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--
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-- T400 Core
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-- T400 Core
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--
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--
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-- $Id: t400_por.vhd,v 1.1 2006-05-07 01:47:51 arniml Exp $
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-- $Id: t400_por.vhd 179 2009-04-01 19:48:38Z arniml $
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--
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--
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-- Wrapper for technology dependent power-on reset circuitry.
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-- Wrapper for technology dependent power-on reset circuitry.
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--
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--
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-- Xilinx Spartan3 flavor.
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-- Xilinx Spartan3 flavor.
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--
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--
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-- Generate a reset upon power-on for specified number of clocks.
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-- Generate a reset upon power-on for specified number of clocks.
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--
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--
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-------------------------------------------------------------------------------
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-------------------------------------------------------------------------------
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--
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--
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-- Copyright (c) 2006, Arnim Laeuger (arnim.laeuger@gmx.net)
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-- Copyright (c) 2006, Arnim Laeuger (arnim.laeuger@gmx.net)
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--
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--
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-- All rights reserved
|
-- All rights reserved
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--
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--
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-- Redistribution and use in source and synthezised forms, with or without
|
-- Redistribution and use in source and synthezised forms, with or without
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-- modification, are permitted provided that the following conditions are met:
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-- modification, are permitted provided that the following conditions are met:
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--
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--
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-- Redistributions of source code must retain the above copyright notice,
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-- Redistributions of source code must retain the above copyright notice,
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-- this list of conditions and the following disclaimer.
|
-- this list of conditions and the following disclaimer.
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--
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--
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-- Redistributions in synthesized form must reproduce the above copyright
|
-- Redistributions in synthesized form must reproduce the above copyright
|
-- notice, this list of conditions and the following disclaimer in the
|
-- notice, this list of conditions and the following disclaimer in the
|
-- documentation and/or other materials provided with the distribution.
|
-- documentation and/or other materials provided with the distribution.
|
--
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--
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-- Neither the name of the author nor the names of other contributors may
|
-- Neither the name of the author nor the names of other contributors may
|
-- be used to endorse or promote products derived from this software without
|
-- be used to endorse or promote products derived from this software without
|
-- specific prior written permission.
|
-- specific prior written permission.
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--
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--
|
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
|
-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
|
-- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
-- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
|
-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
|
-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
-- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
-- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
-- POSSIBILITY OF SUCH DAMAGE.
|
-- POSSIBILITY OF SUCH DAMAGE.
|
--
|
--
|
-- Please report bugs to the author, but before you do so, please
|
-- Please report bugs to the author, but before you do so, please
|
-- make sure that this is not a derivative work and that
|
-- make sure that this is not a derivative work and that
|
-- you have the latest version of this file.
|
-- you have the latest version of this file.
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--
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--
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-------------------------------------------------------------------------------
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-------------------------------------------------------------------------------
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|
|
library ieee;
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.std_logic_1164.all;
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|
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entity t400_por is
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entity t400_por is
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|
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generic (
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generic (
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delay_g : integer := 4;
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delay_g : integer := 4;
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cnt_width_g : integer := 2
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cnt_width_g : integer := 2
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);
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);
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port (
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port (
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clk_i : in std_logic;
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clk_i : in std_logic;
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por_n_o : out std_logic
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por_n_o : out std_logic
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);
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);
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|
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end t400_por;
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end t400_por;
|
|
|
|
|
library ieee;
|
library ieee;
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use ieee.numeric_std.all;
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use ieee.numeric_std.all;
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|
|
architecture spartan of t400_por is
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architecture spartan of t400_por is
|
|
|
-----------------------------------------------------------------------------
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-----------------------------------------------------------------------------
|
-- According to
|
-- According to
|
-- "XST User Guide", Chapter 6 "VHDL Language Support", "Initial Values"
|
-- "XST User Guide", Chapter 6 "VHDL Language Support", "Initial Values"
|
-- XST honors the initial value assigned to a flip-flop. Simple :-)
|
-- XST honors the initial value assigned to a flip-flop. Simple :-)
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--
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--
|
signal por_cnt_q : unsigned(cnt_width_g-1 downto 0)
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signal por_cnt_q : unsigned(cnt_width_g-1 downto 0)
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:= to_unsigned(delay_g, cnt_width_g);
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:= to_unsigned(delay_g, cnt_width_g);
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signal por_n_q : std_logic := '0';
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signal por_n_q : std_logic := '0';
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--
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--
|
-----------------------------------------------------------------------------
|
-----------------------------------------------------------------------------
|
|
|
begin
|
begin
|
|
|
-----------------------------------------------------------------------------
|
-----------------------------------------------------------------------------
|
-- Process por_cnt
|
-- Process por_cnt
|
--
|
--
|
-- Purpose:
|
-- Purpose:
|
-- Generate a power-on reset for the specified number of clocks.
|
-- Generate a power-on reset for the specified number of clocks.
|
--
|
--
|
por_cnt: process (clk_i)
|
por_cnt: process (clk_i)
|
begin
|
begin
|
if clk_i'event and clk_i = '1' then
|
if clk_i'event and clk_i = '1' then
|
if por_cnt_q = 0 then
|
if por_cnt_q = 0 then
|
por_n_q <= '1';
|
por_n_q <= '1';
|
else
|
else
|
por_cnt_q <= por_cnt_q - 1;
|
por_cnt_q <= por_cnt_q - 1;
|
end if;
|
end if;
|
end if;
|
end if;
|
end process por_cnt;
|
end process por_cnt;
|
--
|
--
|
-----------------------------------------------------------------------------
|
-----------------------------------------------------------------------------
|
|
|
por_n_o <= por_n_q;
|
por_n_o <= por_n_q;
|
|
|
end spartan;
|
end spartan;
|
|
|