light.vhd

有關於EP2C的一些程序(EX:I2C,FLASH,IRDA,MUSIC,LED,LIGHT,SRAM,UART,PS2,SPI )

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--*************************************************************************************************
--  CreateDate  :  2007-07-12 
--  ModifData   :  2007-07-12 
--  Description :  Frequency 
--  Author      :  Explorer01 
--  Version     :  V1.0  
--*************************************************************************************************
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-- VHDL library Declarations 
LIBRARY IEEE;
USE IEEE.std_logic_1164.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.std_logic_unsigned.ALL;

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-- The Entity Declarations 
ENTITY Light IS
PORT(
		Period1mS:	IN		std_logic;
		light:		BUFFER	std_logic_vector(7 DOWNTO 0)
	);
END Light;

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-- The Architecture of Entity Declarations 
ARCHITECTURE Behavioral OF Light IS 
	CONSTANT len	: integer := 7;
	
	SIGNAL	banner	: std_logic := '0';
	SIGNAL	clk, clk1, clk2: std_logic;
BEGIN
	clk<=(clk1 AND banner) OR (clk2 AND NOT banner);
	
	------------------------------------------------------------------------------
	-- Clock 
	PROCESS( Period1mS )
		VARIABLE Count : STD_LOGIC_VECTOR(7 DOWNTO 0);
	BEGIN
		
		------------------------------------
		--Period: 1/4S (11111001: 249)
		IF( Period1mS'EVENT AND Period1mS='1' ) THEN 
			IF( Count>"11111001" ) THEN Count := "00000000";
			ELSE                  		Count := Count + 1;
			END IF;
			
			clk1 <= Count(7); 
		END IF; 
	END PROCESS;
	
	------------------------------------------------------------------------------
	-- 
	PROCESS( clk1 )
	BEGIN
		IF( clk1'event AND clk1='1' )THEN
			clk2 <= NOT clk2;
		END IF;
	END PROCESS;
	
	------------------------------------------------------------------------------
	-- 
	PROCESS( clk )
		VARIABLE flag:	bit_vector(2 downto 0):="000";
	BEGIN
		if clk'event and clk='1' then
			if flag="000" then
				light<='1' & light(len downto 1);
				if light(1)='1' then
					flag:="001"; 
				end if;
			elsif flag="001" then
				light<=light(len-1 downto 0) & '0';
				if light(6)='0' then
					flag:="010";
				end if;
			elsif flag="010" then
				light(len downto 4)<=light(len-1 downto 4)&'1';
				light(len-4 downto 0)<='1'&light(len-4 downto 1);
				if light(1)='1' then
					flag:="011";
				end if;
			elsif flag="011" then
				light(len downto 4)<='0'&light(len downto 5);
				light(len-4 downto 0)<=light(len-5 downto 0)&'0';
				if light(2)='0' then
					flag:="100";
				end if;
			elsif flag="100" then
				light(len downto 4)<='1'&light(len downto 5);
				light(len-4 downto 0)<='1'&light(len-4 downto 1);
				if light(1)='1' then
					flag:="101";
				end if;
			elsif flag="101" then
				light<="00000000";
				flag:="110";
			elsif flag="110" then
				banner<=not banner;
				flag:="000";
			end if;
		end if;
	end process;
	
end Behavioral;