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[/] [gamepads/] [trunk/] [gcpad/] [rtl/] [vhdl/] [gcpad_rx.vhd] - Rev 39
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------------------------------------------------------------------------------- -- -- GCpad controller core -- -- $Id: gcpad_rx.vhd,v 1.5 2004-10-09 17:05:12 arniml Exp $ -- -- 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; use work.gcpad_pack.buttons_t; entity gcpad_rx is generic ( reset_level_g : integer := 0; clocks_per_1us_g : integer := 2 ); port ( -- System Interface ------------------------------------------------------- clk_i : in std_logic; reset_i : in std_logic; -- Control Interface ------------------------------------------------------ rx_en_i : in boolean; rx_done_o : out boolean; rx_data_ok_o : out boolean; rx_size_i : in std_logic_vector(3 downto 0); -- Gamepad Interface ------------------------------------------------------ pad_data_i : in std_logic; -- Data Interface --------------------------------------------------------- rx_data_o : out buttons_t ); end gcpad_rx; library ieee; use ieee.numeric_std.all; use work.gcpad_pack.all; architecture rtl of gcpad_rx is component gcpad_sampler generic ( reset_level_g : integer := 0; clocks_per_1us_g : integer := 2 ); port ( clk_i : in std_logic; reset_i : in std_logic; wrap_sample_i : in boolean; sync_sample_i : in boolean; sample_underflow_o : out boolean; pad_data_i : in std_logic; pad_data_o : out std_logic; sample_o : out std_logic ); end component; type state_t is (IDLE, DETECT_TIMEOUT, WAIT_FOR_1, WAIT_FOR_0, FINISHED); signal state_s, state_q : state_t; signal buttons_q, shift_buttons_q : buttons_t; signal save_buttons_s : boolean; signal shift_buttons_s : boolean; signal sync_sample_s : boolean; signal wrap_sample_s : boolean; -- timeout counter counts three sample undeflows constant cnt_timeout_high_c : natural := 3; subtype cnt_timeout_t is natural range 0 to cnt_timeout_high_c; signal cnt_timeout_q : cnt_timeout_t; signal timeout_q : boolean; signal sync_timeout_s : boolean; subtype num_buttons_read_t is unsigned(6 downto 0); signal num_buttons_read_q : num_buttons_read_t; signal all_buttons_read_s : boolean; signal reset_num_buttons_s : boolean; signal pad_data_s : std_logic; signal sample_s : std_logic; signal sample_underflow_s : boolean; signal rx_done_s, rx_done_q : boolean; begin sampler_b : gcpad_sampler generic map ( reset_level_g => reset_level_g, clocks_per_1us_g => clocks_per_1us_g ) port map ( clk_i => clk_i, reset_i => reset_i, wrap_sample_i => wrap_sample_s, sync_sample_i => sync_sample_s, sample_underflow_o => sample_underflow_s, pad_data_i => pad_data_i, pad_data_o => pad_data_s, sample_o => sample_s ); ----------------------------------------------------------------------------- -- Process seq -- -- Purpose: -- Implements the sequential elements of this module. -- seq: process (reset_i, clk_i) variable size_v : std_logic_vector(num_buttons_read_t'range); begin if reset_i = reset_level_g then buttons_q <= (others => '0'); shift_buttons_q <= (others => '0'); state_q <= IDLE; cnt_timeout_q <= cnt_timeout_high_c; timeout_q <= false; num_buttons_read_q <= (others => '0'); rx_done_q <= false; elsif clk_i'event and clk_i = '1' then state_q <= state_s; rx_done_q <= rx_done_s; -- timeout counter if sync_timeout_s then -- explicit preload cnt_timeout_q <= cnt_timeout_high_c; timeout_q <= false; elsif cnt_timeout_q = 0 then -- wrap-around cnt_timeout_q <= cnt_timeout_high_c; timeout_q <= true; elsif sample_underflow_s then -- decrement counter when sampler wraps around cnt_timeout_q <= cnt_timeout_q - 1; end if; -- count remaining number of buttons to read if shift_buttons_s then shift_buttons_q(buttons_t'high downto 1) <= shift_buttons_q(buttons_t'high-1 downto 0); if sample_s = '1' then shift_buttons_q(0) <= '1'; else shift_buttons_q(0) <= '0'; end if; end if; if reset_num_buttons_s then -- explicit preload size_v(num_buttons_read_t'high downto 3) := rx_size_i; size_v(2 downto 0) := (others => '0'); num_buttons_read_q <= unsigned(size_v); elsif shift_buttons_s then -- decrement counter when a button bit has been read if not all_buttons_read_s then num_buttons_read_q <= num_buttons_read_q - 1; end if; end if; -- the buttons if save_buttons_s then buttons_q <= shift_buttons_q; end if; end if; end process seq; -- ----------------------------------------------------------------------------- -- indicates that all buttons have been read all_buttons_read_s <= num_buttons_read_q = 0; ----------------------------------------------------------------------------- -- Process fsm -- -- Purpose: -- Models the controlling state machine. -- fsm: process (state_q, rx_en_i, pad_data_s, wrap_sample_s, all_buttons_read_s, sample_underflow_s, timeout_q) begin sync_sample_s <= false; sync_timeout_s <= false; state_s <= IDLE; shift_buttons_s <= false; save_buttons_s <= false; rx_done_s <= false; reset_num_buttons_s <= false; wrap_sample_s <= false; case state_q is -- IDLE ----------------------------------------------------------------- -- The idle state. when IDLE => if rx_en_i then state_s <= DETECT_TIMEOUT; else -- keep counters synchronized when no reception is running sync_sample_s <= true; sync_timeout_s <= true; reset_num_buttons_s <= true; state_s <= IDLE; end if; when DETECT_TIMEOUT => state_s <= DETECT_TIMEOUT; if pad_data_s = '0' then sync_sample_s <= true; state_s <= WAIT_FOR_1; else -- wait for timeout wrap_sample_s <= true; if timeout_q then rx_done_s <= true; state_s <= IDLE; end if; end if; -- WAIT_FOR_1 ----------------------------------------------------------- -- Sample counter has expired and a 0 bit has been detected. -- We must now wait for pad_data_s to become 1. -- Or abort upon timeout. when WAIT_FOR_1 => if pad_data_s = '0' then if not sample_underflow_s then state_s <= WAIT_FOR_1; else -- timeout while reading buttons! rx_done_s <= true; state_s <= IDLE; end if; else state_s <= WAIT_FOR_0; end if; -- WAIT_FOR_0 ----------------------------------------------------------- -- pad_data_s is at 1 level now and no timeout occured so far. -- We wait for the next 0 level on pad_data_s or abort upon timeout. when WAIT_FOR_0 => -- wait for falling edge of pad data if pad_data_s = '0' then sync_sample_s <= true; -- loop again in any case state_s <= WAIT_FOR_1; if not all_buttons_read_s then shift_buttons_s <= true; end if; else if sample_underflow_s then if all_buttons_read_s then -- last button was read -- so it's ok to timeout state_s <= FINISHED; else -- timeout while reading buttons! rx_done_s <= true; state_s <= IDLE; end if; else state_s <= WAIT_FOR_0; end if; end if; when FINISHED => -- finally save buttons save_buttons_s <= true; rx_done_s <= true; when others => null; end case; end process fsm; -- ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- -- Output Mapping ----------------------------------------------------------------------------- rx_done_o <= rx_done_q; rx_data_ok_o <= save_buttons_s; rx_data_o <= buttons_q; end rtl; ------------------------------------------------------------------------------- -- File History: -- -- $Log: not supported by cvs2svn $ -- Revision 1.4 2004/10/09 00:33:55 arniml -- shift rx_data to button assignment to toplevel -- -- Revision 1.3 2004/10/08 21:18:39 arniml -- move sampler to separate unit -- -- Revision 1.2 2004/10/08 20:51:59 arniml -- turn rx and tx size into bytes instead of bits -- -- Revision 1.1 2004/10/07 21:23:10 arniml -- initial check-in -- -------------------------------------------------------------------------------
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