-------------------------------------------------------------------------------
|
-------------------------------------------------------------------------------
|
--
|
--
|
-- Copyright (C) 2009
|
-- Copyright 2020
|
-- ASTRON (Netherlands Institute for Radio Astronomy) <http://www.astron.nl/>
|
-- ASTRON (Netherlands Institute for Radio Astronomy) <http://www.astron.nl/>
|
-- P.O.Box 2, 7990 AA Dwingeloo, The Netherlands
|
-- P.O.Box 2, 7990 AA Dwingeloo, The Netherlands
|
--
|
--
|
-- This program is free software: you can redistribute it and/or modify
|
-- Licensed under the Apache License, Version 2.0 (the "License");
|
-- it under the terms of the GNU General Public License as published by
|
-- you may not use this file except in compliance with the License.
|
-- the Free Software Foundation, either version 3 of the License, or
|
-- You may obtain a copy of the License at
|
-- (at your option) any later version.
|
|
--
|
--
|
-- This program is distributed in the hope that it will be useful,
|
-- http://www.apache.org/licenses/LICENSE-2.0
|
-- 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
|
-- Unless required by applicable law or agreed to in writing, software
|
-- along with this program. If not, see <http://www.gnu.org/licenses/>.
|
-- distributed under the License is distributed on an "AS IS" BASIS,
|
|
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
-- See the License for the specific language governing permissions and
|
|
-- limitations under the License.
|
--
|
--
|
-------------------------------------------------------------------------------
|
-------------------------------------------------------------------------------
|
|
|
|
|
-- Purpose: Immediately apply reset and synchronously release it at rising clk
|
-- Purpose: Immediately apply reset and synchronously release it at rising clk
|
-- Description:
|
-- Description:
|
-- Using common_areset is equivalent to using common_async with same signal
|
-- Using common_areset is equivalent to using common_async with same signal
|
-- applied to rst and din.
|
-- applied to rst and din.
|
|
|
LIBRARY IEEE, common_pkg_lib;
|
LIBRARY IEEE, common_pkg_lib;
|
USE IEEE.std_logic_1164.ALL;
|
USE IEEE.std_logic_1164.ALL;
|
USE common_pkg_lib.common_pkg.ALL;
|
USE common_pkg_lib.common_pkg.ALL;
|
|
|
ENTITY common_areset IS
|
ENTITY common_areset IS
|
GENERIC (
|
GENERIC (
|
g_rst_level : STD_LOGIC := '1';
|
g_rst_level : STD_LOGIC := '1';
|
g_delay_len : NATURAL := c_meta_delay_len
|
g_delay_len : NATURAL := c_meta_delay_len
|
);
|
);
|
PORT (
|
PORT (
|
in_rst : IN STD_LOGIC;
|
in_rst : IN STD_LOGIC;
|
clk : IN STD_LOGIC;
|
clk : IN STD_LOGIC;
|
out_rst : OUT STD_LOGIC
|
out_rst : OUT STD_LOGIC
|
);
|
);
|
END;
|
END;
|
|
|
|
|
ARCHITECTURE str OF common_areset IS
|
ARCHITECTURE str OF common_areset IS
|
|
|
CONSTANT c_rst_level_n : STD_LOGIC := NOT g_rst_level;
|
CONSTANT c_rst_level_n : STD_LOGIC := NOT g_rst_level;
|
|
|
BEGIN
|
BEGIN
|
|
|
-- When in_rst becomes g_rst_level then out_rst follows immediately (asynchronous reset apply).
|
-- When in_rst becomes g_rst_level then out_rst follows immediately (asynchronous reset apply).
|
-- When in_rst becomes NOT g_rst_level then out_rst follows after g_delay_len cycles (synchronous reset release).
|
-- When in_rst becomes NOT g_rst_level then out_rst follows after g_delay_len cycles (synchronous reset release).
|
|
|
-- This block can also synchronise other signals than reset:
|
-- This block can also synchronise other signals than reset:
|
-- . g_rst_level = '0': output asynchronoulsy follows the falling edge input and synchronises the rising edge input.
|
-- . g_rst_level = '0': output asynchronoulsy follows the falling edge input and synchronises the rising edge input.
|
-- . g_rst_level = '1': output asynchronoulsy follows the rising edge input and synchronises the falling edge input.
|
-- . g_rst_level = '1': output asynchronoulsy follows the rising edge input and synchronises the falling edge input.
|
|
|
u_async : ENTITY work.common_async
|
u_async : ENTITY work.common_async
|
GENERIC MAP (
|
GENERIC MAP (
|
g_rst_level => g_rst_level,
|
g_rst_level => g_rst_level,
|
g_delay_len => g_delay_len
|
g_delay_len => g_delay_len
|
)
|
)
|
PORT MAP (
|
PORT MAP (
|
rst => in_rst,
|
rst => in_rst,
|
clk => clk,
|
clk => clk,
|
din => c_rst_level_n,
|
din => c_rst_level_n,
|
dout => out_rst
|
dout => out_rst
|
);
|
);
|
|
|
END str;
|
END str;
|
|
|
