VHDL code for Debounce Pushbutton

--switch output won't go high till button is remained press for atleast 3 clock cycles
-- here is the code for 6 switches

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;


entity Switch_debounce is

port(cclk,clr: in std_logic;
sw_in: in std_logic_vector(5 downto 0);
sw_out: out std_logic_vector(5 downto 0));

end Switch_debounce;

architecture Behavioral of Switch_debounce is

signal delay1,delay2,delay3:std_logic_vector(5 downto 0);

begin
process(cclk,clr)
begin

if clr='1' then
delay1<="000000";
delay2<="000000";
delay3<="000000";

elsif cclk'event and cclk='1' then

delay1<=sw_in;
delay2<=delay1;
delay3<=delay2;

end if;

end process;

sw_out<=delay1 and delay2 and delay3;


end Behavioral;





--Testbench


LIBRARY ieee;
USE ieee.std_logic_1164.ALL;



ENTITY switch_debounce_testbench IS
END switch_debounce_testbench;

ARCHITECTURE behavior OF switch_debounce_testbench IS

    -- Component Declaration for the Unit Under Test (UUT)

    COMPONENT Switch_debounce
    PORT(
         cclk : IN  std_logic;
         clr : IN  std_logic;
         sw_in : IN  std_logic_vector(5 downto 0);
         sw_out : OUT  std_logic_vector(5 downto 0)
        );
    END COMPONENT;
   

   --Inputs
   signal cclk : std_logic := '0';
   signal clr : std_logic := '0';
   signal sw_in : std_logic_vector(5 downto 0) := (others => '0');

     --Outputs
   signal sw_out : std_logic_vector(5 downto 0);

   -- Clock period definitions
   constant cclk_period : time := 2 ms;

BEGIN

    -- Instantiate the Unit Under Test (UUT)
   uut: Switch_debounce PORT MAP (
          cclk =>cclk,
          clr =>clr,
          sw_in =>sw_in,
          sw_out =>sw_out
        );

   -- Clock process definitions
   cclk_process :process
   begin
        cclk <= '0';
        wait for cclk_period/2;
        cclk <= '1';
        wait for cclk_period/2;
   end process;


   -- Stimulus process
   stim_proc: process
   begin       
      -- hold reset state for 100 ns.
      wait for 100 ns;   

      clr<='1';
       
 wait for 100 ns;   

clr<='0';
      -- insert stimulus  here
sw_in(1<='0';
wait for 2 ms;
sw_in(1)<='1';
wait for 3 ms;
sw_in(1)<='0';
wait for 4 ms;
sw_in(1)<='1';
wait for 8 ms;
sw_in(1)<='0';


      wait;
   end process;

END;

-- Waveform