autorepeat.vhd

This is a project about PWM. Application in motor speed control

---------------------------------------------------------------------------
-- autorepeat
-- pass on pulse, iff long then start repeating pulses (e.g., keyboard)
---------------------------------------------------------------------------

library ieee;

use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.std_logic_arith.all;

entity autorepeat is
    port (
        clk: in std_logic;
        input: in std_logic;
        output: out std_logic
    );
end entity;

architecture behaviour of autorepeat is

type statetype is (stdby, press0, press1, press2);
signal state: statetype := stdby;
signal counter : std_logic_vector(31 downto 0);

begin
  process 
    begin
      wait until rising_edge(clk);
      case state is

        when stdby =>
	  output <= '0';
	  counter <= x"02000000";
          if (input = '1') then
	    state <= press0;
	  end if;

	when press0 =>
	  output <= '1';
	  if (input = '0') then
	    state <= stdby;
	  end if;
	  -- else when timeout goto repeater
	  counter <= counter - '1';
	  if (counter = x"00000000") then
	    state <= press1;
	  end if;

        when press1 =>
	  if (input = '0') then
	    state <= stdby;
	  end if;
          -- else repeat 0-1
	  output <= '0';
	  counter <= counter + '1';
	  if (counter > x"00040000") then
	    counter <= (others => '0');
	    state <= press2;
	  end if;

         when press2 =>
	  if (input = '0') then
	    state <= stdby;
	  end if;
	  -- else repeat 0-1
	  output <= '1';
	  counter <= counter + '1';
	  if (counter > x"00040000") then
	    counter <= (others => '0');
	    state <= press1;
	  end if;

	end case;
    end process;
end behaviour;