APPLICATION NOTES:
Provided by:
Tyler Brandon, Chris Blasko, Kevin Lister.

This file contains  a PS/2 Mouse controller.  It should be noted that 
while this code is mostly functioning, all of the bugs have not been
worked out.  So if you need a template these programs are a good place 
to start.  Also, as the program is developed the newer versions will be
posted to the Application notes.

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-- m2.vhd (PS/2 mouse code)
--
-- compiles without errors
-- Does not produce the correct results when hooked up to the Altera Board
-- 
-- Under construction

-- By Tyler Brandon, Chris Blasko, Kevin Lister
-- U of Alberta
--
library ieee;
use  ieee.std_logic_1164.ALL;
use  ieee.std_logic_arith.all;
use  ieee.std_logic_unsigned.all;

entity m2 is
	
  port( Clock			: in std_logic;     --system clock (pin 91), 25.175MHz
        mouse_data		: in std_logic;     --data from the PS/2 mouse (pin 31)
		mouse_clk		: in std_logic;		--Clock from the PS/2 mouse (pin 30)

        --MouseX	: buffer std_logic_vector(9 downto 0); --current X position of mouse
        --MouseY	: buffer std_logic_vector(8 downto 0);  --current Y position of mouse
		MouseL	: out std_logic;
		MouseR	: out std_logic );	--Left mouse button
       
end m2;

architecture behavior of m2 is

	--signal IncommingDataDetected : std_logic;                       --Set, when start bit of packet found

	signal data					: std_logic_vector(34 downto 0);   --Data from the mouse data packet

	signal clkCounter			: integer range 0 to 1007;
	signal waitCounter 			: integer range 0 to 1800;        --Division of the clock
	signal reciving_data		: std_logic;
	

begin

	process( Clock )
	begin
		if rising_edge( Clock ) then
			if mouse_clk = '1' then
				waitCounter <= waitCounter + 1;
							
			else
				reciving_data <= '1';
				waitCounter <= 0;
				
			end if;

			if waitCounter > 1762 then	--if 70us has passed without the mouse_clk
										--going low, then re-synchronize the system
				reciving_data <= '0';
				waitCounter <= 0;
			end if;

		end if;
	end process;

	process (mouse_clk)

	variable NumDataBits	: integer range 0 to 34;	--Number of bits captured

	begin

		if (mouse_clk'EVENT and mouse_clk = '1') then  

			if reciving_data = '1' then

				data(NumDatabits) <= mouse_data;
				NumDatabits := NumDatabits + 1;

				if NumDatabits = 33 then
					
					MouseL <= data(1);
					MouseR <= data(2);
				end if;

			else
				NumDatabits := 0;
			end if;

		end if;

	end process;		


	--	if reset = '0' then
    		  --MouseL                <= '0';         --mouse button not pressed
	
--			  mouse_clk				<= '1';
--			  NumDatabits			<= 0;

			  
			  --Starting coordinates
--    		  MouseX                <= START_X;   --place mouse initially in 2nd column
--		      MouseY                <= START_Y;   --place mouse initially in 3rd row

--		elsif NumDatabits <= 33 then
			
--				clkCounter <= clkCounter + 1;

--				if clkCounter = 504 then
--					mouse_clk <= '1';
--					data(NumDatabits) <= MouseData;
--					NumDatabits <= NumDatabits + 1;
--				elsif clkCounter = 1007 then
--					clkCounter <= 0;
--					mouse_clk <= '0';
--				end if;
--		else
			
--				waitCounter <= waitCounter + 1;			

--				if waitCounter = 386352 then
--					NumDatabits <= 0;
--					waitCounter <= 0;
--				end if;

--				MouseL <= data(1);

--		end if;

--	end if;

--  end process;

end behavior;