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--

-- PIC16xx compatible microcontroller core

--

-- Version : 0146

--

-- Copyright (c) 2001-2002 Daniel Wallner (jesus@opencores.org)

--

-- All rights reserved

--

-- Redistribution and use in source and synthezised forms, with or without

-- modification, are permitted provided that the following conditions are met:

--

-- Redistributions of source code must retain the above copyright notice,

-- this list of conditions and the following disclaimer.

--

-- Redistributions in synthesized form must reproduce the above copyright

-- notice, this list of conditions and the following disclaimer in the

-- documentation and/or other materials provided with the distribution.

--

-- 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

-- specific prior written permission.

--

-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

-- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE

-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

-- 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

-- POSSIBILITY OF SUCH DAMAGE.

--

-- Please report bugs to the author, but before you do so, please

-- make sure that this is not a derivative work and that

-- you have the latest version of this file.

--

-- The latest version of this file can be found at:

--      http://www.opencores.org/cvsweb.shtml/t51/

--

-- Limitations :

--      Registers implemented in this entity are INDF, PCL, STATUS, FSR, (PCLATH)

--      other registers must be implemented externally including GPR

--

-- File history :

--

library IEEE;

use IEEE.std_logic_1164.all;

entity PPX_Port is

        port(

                Clk                     : in std_logic;

                Reset_n         : in std_logic;

                Port_CS         : in std_logic;

                Rd                      : in std_logic;

                Wr                      : in std_logic;

                Tris_Rd         : in std_logic;

                Tris_Wr         : in std_logic;

                Data_In         : in std_logic_vector(7 downto 0);

                Data_Out        : out std_logic_vector(7 downto 0);

                IOPort          : inout std_logic_vector(7 downto 0)

        );

end PPX_Port;

architecture rtl of PPX_Port is

        signal Tris                     : std_logic_vector(7 downto 0);

        signal Port_Output      : std_logic_vector(7 downto 0);

        signal Port_Input       : std_logic_vector(7 downto 0);

begin

        IOPort(0) <= Port_Output(0) when Tris(0) = '0' else 'Z';

        IOPort(1) <= Port_Output(1) when Tris(1) = '0' else 'Z';

        IOPort(2) <= Port_Output(2) when Tris(2) = '0' else 'Z';

        IOPort(3) <= Port_Output(3) when Tris(3) = '0' else 'Z';

        IOPort(4) <= Port_Output(4) when Tris(4) = '0' else 'Z';

        IOPort(5) <= Port_Output(5) when Tris(5) = '0' else 'Z';

        IOPort(6) <= Port_Output(6) when Tris(6) = '0' else 'Z';

        IOPort(7) <= Port_Output(7) when Tris(7) = '0' else 'Z';

        Data_Out <= Port_Input when Port_CS = '1' and Rd = '1' else "ZZZZZZZZ";

        process (Clk)

        begin

                if Clk'event and Clk = '1' then

                        Port_Input <= IOPort;   -- Synchronise input

                        if Port_CS = '1' and Wr = '1' then

                                Port_Output <= Data_In;

                                Port_Input <= Data_In;

                        end if;

                end if;

        end process;

        Data_Out <= Tris when Tris_Rd = '1' else "ZZZZZZZZ";

        process (Reset_n, Clk)

        begin

                if Reset_n = '0' then

                        Tris <= "11111111";

                elsif Clk'event and Clk = '1' then

                        if Tris_Wr = '1' then

                                Tris <= Data_In;

                        end if;

                end if;

        end process;

end;