Subversion Repositories gamepads

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

--

-- GCpad controller core

--

-- $Id: gcpad_ctrl.vhd 41 2009-04-01 19:58:04Z arniml $

--

-- Copyright (c) 2004, Arnim Laeuger (arniml@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/gamepads/

--

-- The project homepage is located at:

--      http://www.opencores.org/projects.cgi/web/gamepads/overview

--

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

library ieee;

use ieee.std_logic_1164.all;

entity gcpad_ctrl is

  generic (

    reset_level_g :     integer := 0

  );

  port (

    -- System Interface -------------------------------------------------------

    clk_i         : in  std_logic;

    reset_i       : in  std_logic;

    pad_request_i : in  std_logic;

    pad_avail_o   : out std_logic;

    rx_timeout_o  : out std_logic;

    -- Control Interface ------------------------------------------------------

    tx_start_o    : out boolean;

    tx_finished_i : in  boolean;

    rx_en_o       : out boolean;

    rx_done_i     : in  boolean;

    rx_data_ok_i  : in  boolean

  );

end gcpad_ctrl;

use work.gcpad_pack.all;

architecture rtl of gcpad_ctrl is

  type state_t is (IDLE,

                   TX,

                   RX1_START,

                   RX1_WAIT,

                   RX2_START,

                   RX2_WAIT,

                   RX3_START,

                   RX3_WAIT,

                   RX4_START,

                   RX4_WAIT);

  signal state_s,

         state_q  : state_t;

  signal set_txrx_finished_s    : boolean;

  signal enable_txrx_finished_s : boolean;

  signal txrx_finished_q        : std_logic;

  signal timeout_q : std_logic;

begin

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

  -- Process seq

  --

  -- Purpose:

  --   Implements the sequential elements.

  --

  seq: process (reset_i, clk_i)

  begin

    if reset_i = reset_level_g then

      state_q         <= IDLE;

      txrx_finished_q <= '0';

      timeout_q <= '1';

    elsif clk_i'event and clk_i = '1' then

      state_q <= state_s;

      -- transmit/receive finished flag

      if set_txrx_finished_s then

        txrx_finished_q <= '1';

      elsif pad_request_i = '1' then

        txrx_finished_q <= '0';

      end if;

      if pad_request_i = '1' then

        timeout_q <= '1';

      elsif rx_data_ok_i then

        timeout_q <= '0';

      end if;

    end if;

  end process seq;

  --

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

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

  -- Process fsm

  --

  -- Purpose:

  --   Models the controlling state machine.

  --

  fsm: process (state_q,

                tx_finished_i,

                rx_done_i,

                pad_request_i)

  begin

    rx_en_o                <= false;

    state_s                <= IDLE;

    tx_start_o             <= false;

    set_txrx_finished_s    <= false;

    enable_txrx_finished_s <= false;

    case state_q is

      when IDLE =>

        -- enable output of txrx_finished flag

        -- the flag has to be suppressed while the FSM probes four times

        enable_txrx_finished_s <= true;

        if pad_request_i = '1' then

          state_s    <= TX;

          tx_start_o <= true;

        else

          state_s    <= IDLE;

        end if;

      when TX =>

        if not tx_finished_i then

          state_s <= TX;

        else

          state_s <= RX1_START;

        end if;

      when RX1_START =>

        rx_en_o <= true;

        state_s <= RX1_WAIT;

      when RX1_WAIT =>

        if rx_done_i then

          state_s <= RX2_START;

        else

          state_s <= RX1_WAIT;

        end if;

      when RX2_START =>

        rx_en_o <= true;

        state_s <= RX2_WAIT;

      when RX2_WAIT =>

        if rx_done_i then

          state_s <= RX3_START;

        else

          state_s <= RX2_WAIT;

        end if;

      when RX3_START =>

        rx_en_o <= true;

        state_s <= RX3_WAIT;

      when RX3_WAIT =>

        if rx_done_i then

          state_s <= RX4_START;

        else

          state_s <= RX3_WAIT;

        end if;

      when RX4_START =>

        rx_en_o <= true;

        state_s <= RX4_WAIT;

      when RX4_WAIT =>

        if rx_done_i then

          state_s             <= IDLE;

          set_txrx_finished_s <= true;

        else

          state_s             <= RX4_WAIT;

        end if;

      when others =>

        null;

    end case;

  end process fsm;

  --

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

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

  -- Output mapping

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

  pad_avail_o  <=   txrx_finished_q

                  when enable_txrx_finished_s else

                    '0';

  rx_timeout_o <=   timeout_q

                  when enable_txrx_finished_s else

                    '0';

end rtl;