stop_3.vhd

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-- Company:
-- Engineer:
--
-- Create Date:    23:20:28 11/20/2013
-- Design Name:
-- Module Name:    stop_3 - Behavioral
-- Project Name:
-- Target Devices:
-- Tool versions:
-- Description:
--
-- Dependencies:
--
-- Revision:
-- Revision 0.01 - File Created
-- Additional Comments:
--
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library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

-- Uncomment the following library declaration if using
-- arithmetic functions with Signed or Unsigned values
--use IEEE.NUMERIC_STD.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

-- Uncomment the following library declaration if instantiating
-- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity stop_3 is
    Port ( iCLK : in  STD_LOGIC;
           iSTART : in  STD_LOGIC;
           iSTOP : in  STD_LOGIC;
           iCONTINUE : in  STD_LOGIC;
           iRESET : in  STD_LOGIC;
           oSECONDS : out  STD_LOGIC_VECTOR (7 downto 0));
end stop_3;

architecture Behavioral of stop_3 is
    signal sSTATE : STD_LOGIC_VECTOR (1 downto 0);
    signal sSECONDS : STD_LOGIC_VECTOR (7 downto 0);
    signal sPRESCALER : STD_LOGIC_VECTOR (7 downto 0);
    signal sPRESCALER_OUT : STD_LOGIC;
begin


process(iCLK) begin
    if(iCLK'event and iCLK = '1') then
        if	(iRESET 		= '0'		) 	then sSTATE <= "00";
        elsif	(iSTOP 			= '0'		) 	then sSTATE <= "01";
        elsif	(iSTART			= '0'		) 	then sSTATE <= "10";
        elsif	(iCONTINUE      	= '0'		)	then sSTATE <= "11";
        elsif	(sSTATE 		= "10"      	) 	then sSTATE <= "11";
        end if;
    end if;
end process;


process(iCLK) begin
    if(iCLK'event and iCLK = '1') then

        if	(sSTATE(0) = '0') then sPRESCALER <= (others => '0');
        elsif	(sSTATE(1) = '1') then
            if(sPRESCALER = "00010111") then
                sPRESCALER <= (others => '0');
                sPRESCALER_OUT <= '1';
            else
                sPRESCALER_OUT <= '0';
                sPRESCALER <= sPRESCALER + 1;
            end if;
        end if;

    end if;
end process;


process(iCLK) begin
    if(iCLK'event and iCLK = '1') then
        if(sSTATE(0) = '0') then
            sSECONDS <= (others => '0');
        elsif (sPRESCALER_OUT = '1') then
            sSECONDS <= sSECONDS + 1;
        end if;
    end if;
end process;

oSECONDS <= sSECONDS;

end Behavioral;