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-- Author: Patrick Lehmann
-- License: MIT
--
-- A generic counter module used in the StopWatch example.
--
library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.numeric_std.all;
use work.Utilities_pkg.all;
entity Debouncer is
generic (
CLOCK_PERIOD : time := 10 ns;
DEBOUNCE_TIME : time := 3 ms;
BITS : positive
);
port (
Clock : in std_logic;
Input : in std_logic_vector(BITS - 1 downto 0);
Output : out std_logic_vector(BITS - 1 downto 0) := (others => '0')
);
end entity;
architecture rtl of Debouncer is
constant DEBOUNCE_COUNTER_MAX : positive := DEBOUNCE_TIME / (CLOCK_PERIOD* ite(IS_SIMULATION, 20, 1));
constant DEBOUNCE_COUNTER_BITS : positive := log2(DEBOUNCE_COUNTER_MAX);
begin
assert false report "CLOCK_PERIOD: " & time'image(CLOCK_PERIOD);
assert false report "DEBOUNCE_TIME: " & time'image(DEBOUNCE_TIME);
--assert false report "DEBOUNCE_COUNTER_MAX: " & to_string(10 ns);
--assert false report "INTEGER'high: " & integer'image(integer'high);
genBits: for i in Input'range generate
signal DebounceCounter : signed(DEBOUNCE_COUNTER_BITS downto 0) := to_signed(DEBOUNCE_COUNTER_MAX - 3, DEBOUNCE_COUNTER_BITS + 1);
begin
process (Clock)
begin
if rising_edge(Clock) then
-- restart counter, whenever Input(i) was unstable within DEBOUNCE_TIME_MS
if (Input(i) /= Output(i)) then
DebounceCounter <= DebounceCounter - 1;
else
DebounceCounter <= to_signed(DEBOUNCE_COUNTER_MAX - 3, DebounceCounter'length);
end if;
-- latch input bit, if input was stable for DEBOUNCE_TIME_MS
if (DebounceCounter(DebounceCounter'high) = '1') then
Output(i) <= Input(i);
end if;
end if;
end process;
end generate;
end architecture;
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