Mudanças entre as edições de "Dicas de como eliminar o repique das chaves mecânicas"

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;Código de www.labbookpages.co.uk:
 
;Código de www.labbookpages.co.uk:
 
<syntaxhighlight lang=vhdl>
 
<syntaxhighlight lang=vhdl>
 +
library ieee;
 +
use ieee.std_logic_1164.all;
 +
use ieee.numeric_std.all;
  
 +
entity SwitchDebouncer is
 +
generic (CLK_FREQ : positive;
 +
NUM_SWITCHES : positive);
 +
port ( clk : in std_logic;
 +
reset : in std_logic;
 +
switchesIn : in std_logic_vector(NUM_SWITCHES-1 downto 0);
 +
switchesOut : out std_logic_vector(NUM_SWITCHES-1 downto 0));
 +
end entity;
 +
 +
architecture Structural of SwitchDebouncer is
 +
signal sample : std_logic;
 +
begin
 +
 +
SampleGen : process(clk)
 +
constant SAMPLE_COUNT_MAX : integer := (CLK_FREQ / 2000) - 1; -- 500 us
 +
variable counter : integer range 0 to SAMPLE_COUNT_MAX;
 +
begin
 +
if (clk'event and clk='1') then
 +
if (reset='1') then
 +
sample <= '0';
 +
counter := 0;
 +
else
 +
if (counter=SAMPLE_COUNT_MAX) then
 +
counter := 0;
 +
sample <= '1';
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else
 +
sample <= '0';
 +
counter := counter + 1;
 +
end if;
 +
end if;
 +
end if;
 +
end process;
 +
 +
DebounceGen : for sw in 0 to NUM_SWITCHES-1 generate
 +
constant PULSE_COUNT_MAX : integer := 20;
 +
signal sync : std_logic_vector(1 downto 0);
 +
signal counter : integer range 0 to PULSE_COUNT_MAX;
 +
begin
 +
Debounce : process(clk)
 +
begin
 +
if (clk'event and clk='1') then
 +
if (reset='1') then
 +
sync <= (others => '0');
 +
counter <= 0;
 +
switchesOut(sw) <= '0';
 +
else
 +
sync <= sync(0) & switchesIn(sw);
 +
if (sync(1)='0') then -- Switch not pressed
 +
counter <= 0;
 +
switchesOut(sw) <= '0';
 +
 +
elsif(sample = '1') then -- Switch pressed
 +
if (counter=PULSE_COUNT_MAX) then
 +
switchesOut(sw) <= '1';
 +
else
 +
counter <= counter + 1;
 +
end if;
 +
end if;
 +
end if;
 +
end if;
 +
end process;
 +
end generate;
 +
end Structural;
 
</syntaxhighlight>
 
</syntaxhighlight>
 
;Código 1 de eewiki.net:
 
;Código 1 de eewiki.net:

Edição das 10h17min de 16 de dezembro de 2015

O repique (bouncing) das chaves mecânicas é um processo natural do chaveamento. Em circuitos sensíveis ao repique é necessário eliminá-lo utilizando ou circuitos de hardware analógico, ou software, ou hardware digital. Nos sites a seguir o processo é explicado, e são apresentadas algumas soluções.

Códigos VHDL

Código de www.labbookpages.co.uk
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity SwitchDebouncer is
	generic (CLK_FREQ			: positive;
				NUM_SWITCHES	: positive);
	port (	clk				: in	std_logic;
				reset				: in	std_logic;
				switchesIn		: in	std_logic_vector(NUM_SWITCHES-1 downto 0);
				switchesOut		: out	std_logic_vector(NUM_SWITCHES-1 downto 0));
end entity;

architecture Structural of SwitchDebouncer is
	signal sample	: std_logic;
begin

	SampleGen : process(clk)
		constant SAMPLE_COUNT_MAX	: integer := (CLK_FREQ / 2000) - 1;	-- 500 us
		variable counter				: integer range 0 to SAMPLE_COUNT_MAX;
	begin
		if (clk'event and clk='1') then
			if (reset='1') then
				sample	<= '0';
				counter	:= 0;
			else
				if (counter=SAMPLE_COUNT_MAX) then
					counter	:= 0;
					sample	<= '1';
				else
					sample	<= '0';
					counter	:= counter + 1;
				end if;
			end if;
		end if;
	end process;

	DebounceGen : for sw in 0 to NUM_SWITCHES-1 generate
		constant PULSE_COUNT_MAX	: integer := 20;
		signal sync						: std_logic_vector(1 downto 0);
		signal counter					: integer range 0 to PULSE_COUNT_MAX;
	begin
		Debounce : process(clk)
		begin
			if (clk'event and clk='1') then
				if (reset='1') then
					sync					<= (others => '0');
					counter				<= 0;
					switchesOut(sw)	<= '0';
				else
					sync <= sync(0) & switchesIn(sw);
					if (sync(1)='0') then		-- Switch not pressed
						counter <= 0;
						switchesOut(sw) <= '0';

					elsif(sample = '1') then	-- Switch pressed
						if (counter=PULSE_COUNT_MAX) then
							switchesOut(sw) <= '1';
						else
							counter <= counter + 1;
						end if;
					end if;
				end if;
			end if;
		end process;
	end generate;
end Structural;
Código 1 de eewiki.net
Código 2 de eewiki.net
Disponível em “https://wiki.sj.ifsc.edu.br/index.php?title=Dicas_de_como_eliminar_o_repique_das_chaves_mecânicas&oldid=100466”