jens
70e48af3ab
git-svn-id: http://moon:8086/svn/vhdl/trunk@1036 cc03376c-175c-47c8-b038-4cd826a8556b
92 lines
2.3 KiB
VHDL
92 lines
2.3 KiB
VHDL
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-- Company:
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-- Engineer:
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--
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-- Create Date: 19:34:24 10/23/05
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-- Design Name:
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-- Module Name: debounce - Behavioral
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-- Project Name:
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-- Target Device:
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-- Tool versions:
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-- Description:
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--
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-- Dependencies:
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--
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-- Revision:
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-- Revision 0.01 - File Created
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-- Additional Comments:
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--
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-----------------------------------------------------------------------
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-- $Header: D:\usr\cvsroot/VHDL/lib/misc/debounce.vhd,v 1.1 2008/08/23 08:20:29 Jens Exp $
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-----------------------------------------------------------------------
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library IEEE;
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use IEEE.STD_LOGIC_1164.ALL;
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use IEEE.STD_LOGIC_ARITH.ALL;
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use IEEE.STD_LOGIC_UNSIGNED.ALL;
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---- Uncomment the following library declaration if instantiating
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---- any Xilinx primitives in this code.
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--library UNISIM;
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--use UNISIM.VComponents.all;
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entity debounce is
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Generic ( ncyc_latency : integer := 100);
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Port ( rst : in std_logic;
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clk : in std_logic;
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input : in std_logic;
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output : out std_logic);
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end debounce;
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architecture Behavioral of debounce is
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type debounce_state_t is (init_st, wait_st, rel_st);
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signal debounce_cs : debounce_state_t;
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signal debounce_ns : debounce_state_t;
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signal count : integer range 0 to ncyc_latency;
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signal input_last : std_logic;
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begin
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debounce_clk: process(rst, clk, debounce_ns, debounce_cs, input)
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begin
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if (rst = '1') then
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count <= 0;
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output <= input;
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input_last <= input;
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else
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if rising_edge(clk) then
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debounce_cs <= debounce_ns;
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if (debounce_cs = wait_st) then
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if (count /= 0) then
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count <= count - 1;
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end if;
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else
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count <= ncyc_latency;
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if (debounce_cs = rel_st) then
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output <= input;
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input_last <= input;
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end if;
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end if;
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end if;
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end if;
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end process;
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debounce_in: process(rst, clk, input, input_last, debounce_cs, count)
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begin
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debounce_ns <= debounce_cs;
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case debounce_cs is
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when init_st =>
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if (input /= input_last) then
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debounce_ns <= wait_st;
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end if;
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when wait_st =>
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if (count = 0) then
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debounce_ns <= rel_st;
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end if;
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when others =>
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debounce_ns <= init_st;
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end case;
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end process;
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end Behavioral;
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