[1799] | 1 | ------------------------------------------------------------------------------- |
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| 2 | -- |
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| 3 | -- SD/MMC Bootloader |
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| 4 | -- Generic counter module |
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| 5 | -- |
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| 6 | -- $Id: spi_counter.vhd 77 2009-04-01 19:53:14Z arniml $ |
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| 7 | -- |
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| 8 | -- Copyright (c) 2005, Arnim Laeuger (arniml@opencores.org) |
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| 9 | -- |
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| 10 | -- All rights reserved, see COPYING. |
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| 11 | -- |
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| 12 | -- Redistribution and use in source and synthezised forms, with or without |
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| 13 | -- modification, are permitted provided that the following conditions are met: |
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| 14 | -- |
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| 15 | -- Redistributions of source code must retain the above copyright notice, |
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| 16 | -- this list of conditions and the following disclaimer. |
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| 17 | -- |
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| 18 | -- Redistributions in synthesized form must reproduce the above copyright |
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| 19 | -- notice, this list of conditions and the following disclaimer in the |
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| 20 | -- documentation and/or other materials provided with the distribution. |
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| 21 | -- |
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| 22 | -- Neither the name of the author nor the names of other contributors may |
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| 23 | -- be used to endorse or promote products derived from this software without |
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| 24 | -- specific prior written permission. |
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| 25 | -- |
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| 26 | -- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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| 27 | -- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
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| 28 | -- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
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| 29 | -- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE |
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| 30 | -- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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| 31 | -- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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| 32 | -- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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| 33 | -- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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| 34 | -- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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| 35 | -- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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| 36 | -- POSSIBILITY OF SUCH DAMAGE. |
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| 37 | -- |
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| 38 | -- Please report bugs to the author, but before you do so, please |
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| 39 | -- make sure that this is not a derivative work and that |
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| 40 | -- you have the latest version of this file. |
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| 41 | -- |
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| 42 | -- The latest version of this file can be found at: |
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| 43 | -- http://www.opencores.org/projects.cgi/web/spi_boot/overview |
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| 44 | -- |
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| 45 | ------------------------------------------------------------------------------- |
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| 46 | |
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| 47 | library ieee; |
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| 48 | use ieee.std_logic_1164.all; |
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| 49 | |
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| 50 | |
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| 51 | entity spi_counter is |
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| 52 | |
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| 53 | generic ( |
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| 54 | cnt_width_g : integer := 4; |
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| 55 | cnt_max_g : integer := 15 |
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| 56 | ); |
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| 57 | |
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| 58 | port ( |
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| 59 | clk_i : in std_logic; |
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| 60 | reset_i : in boolean; |
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| 61 | cnt_en_i : in boolean; |
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| 62 | cnt_o : out std_logic_vector(cnt_width_g-1 downto 0); |
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| 63 | cnt_ovfl_o : out boolean |
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| 64 | ); |
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| 65 | |
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| 66 | end spi_counter; |
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| 67 | |
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| 68 | |
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| 69 | library ieee; |
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| 70 | use ieee.numeric_std.all; |
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| 71 | use work.spi_boot_pack.all; |
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| 72 | |
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| 73 | architecture rtl of spi_counter is |
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| 74 | |
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| 75 | signal cnt_q : unsigned(cnt_width_g-1 downto 0); |
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| 76 | signal cnt_ovfl_s : boolean; |
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| 77 | |
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| 78 | begin |
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| 79 | |
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| 80 | cnt: process (clk_i, reset_i) |
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| 81 | begin |
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| 82 | if reset_i then |
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| 83 | cnt_q <= (others => '0'); |
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| 84 | |
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| 85 | elsif clk_i'event and clk_i = '1' then |
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| 86 | if cnt_en_i then |
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| 87 | if not cnt_ovfl_s then |
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| 88 | cnt_q <= cnt_q + 1; |
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| 89 | else |
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| 90 | cnt_q <= (others => '0'); |
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| 91 | end if; |
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| 92 | end if; |
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| 93 | end if; |
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| 94 | end process cnt; |
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| 95 | |
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| 96 | cnt_ovfl_s <= cnt_q = cnt_max_g; |
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| 97 | |
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| 98 | |
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| 99 | ----------------------------------------------------------------------------- |
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| 100 | -- Output Mapping |
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| 101 | ----------------------------------------------------------------------------- |
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| 102 | cnt_ovfl_o <= cnt_ovfl_s; |
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| 103 | cnt_o <= std_logic_vector(cnt_q); |
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| 104 | |
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| 105 | end rtl; |
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