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-- Company:
-- Engineer:
--
-- Create Date:    12:25:53 03/18/2009
-- Design Name:
-- Module Name:    clock - 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;
use IEEE.STD_LOGIC_ARITH.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 clock is
    Port ( clockSource : in STD_LOGIC;  -- clock pulse from micro
           reset : in  STD_LOGIC;        -- reset pulse from micro
           microAck : in STD_LOGIC;      -- acknowledgement from micro
              digit : out  STD_LOGIC_VECTOR (3 downto 0);
                                                      -- numbers to micro
              cpldRts : out STD_LOGIC);     -- ready to send to micro (ACTIVE LOW)
end clock;

architecture Behavioral of clock is

signal hunthsCount : std_logic_vector(3 downto 0);
signal tenthsCount : std_logic_vector(3 downto 0);
signal secondCount : std_logic_vector(3 downto 0);
signal tenSecCount : std_logic_vector(3 downto 0);
signal controlFlag : std_logic_vector(1 downto 0);

begin                                                        

process(reset, clockSource)
begin
if reset = '1' then
    hunthsCount <= "0000";
    tenthsCount <= "0000";
    secondCount <= "0000";
    tenSecCount <= "0000";
    controlFlag <= "10";
    cpldRts <= '1';
elsif microAck = '1' then
    cpldRts <= '1';
elsif clockSource'event and clockSource = '1' then
   
    if controlFlag = "00" then
        digit <= hunthsCount;
        controlFlag <= "01";
        cpldRts <= '0';
       
    elsif controlFlag = "01" then
        digit <= tenthsCount;
        controlFlag <= "10";
        cpldRts <= '0';
       
    elsif controlFlag = "10" then
        digit <= secondCount;                                                        
        controlFlag <= "11";
        cpldRts <= '0';
       
    elsif controlFlag = "11" then
        digit <= tenSecCount;
        controlFlag <= "00";
        cpldRts <= '0';
               
        if hunthsCount <= "1000" then
            hunthsCount <= hunthsCount + "1";
   
        else
            hunthsCount <= "0000";
           
            if tenthsCount <= "1000" then
                tenthsCount <= tenthsCount + "1";
   
            else
                tenthscount <= "0000";
               
                if secondCount <= "1000" then
                    secondCount <= secondCount + "1";
                   
                else
                    secondCount <= "0000";
                   
                    if tenSecCount <= "1000" then
                        tenSecCount <= tenSecCount + "1";
                       
                    else
                        tenSecCount <= "0000";
                       
                    end if;
                end if;
            end if;
        end if;
    end if;
       
end if;
end process;

end Behavioral;