vga.vhd

FPGA驱动VGA接口显示字符

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-- Company: 
-- Engineer:       Likee000
-- 
-- Create Date:    08:51:13 05/03/2008 
-- Design Name: 
-- Module Name:    VGA_Module - Behavioral 
-- Project Name:   
-- Target Devices: 
-- Tool versions:  xilinx SPARTAN-3
-- Description: 
--
-- Dependencies: 
--
-- Revision:  
-- Revision 0.01 - File Created
-- Additional Comments: 
--
----------------------------------------------------------------------------------
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;


entity VGA_Module is
    Port ( clk50_in : in std_logic;
           Red_out : out std_logic;
           Green_out : out std_logic;
           Blue_out : out std_logic;
           hs_out : out std_logic;
           vs_out : out std_logic);
end VGA_Module;

architecture Behavioral of VGA_Module is
		signal Clk25					: std_logic;
		signal Horizontal_Counter	: std_logic_vector (9 downto 0);
		signal Vertical_Counter		: std_logic_vector (9 downto 0);

begin
--Generate 25Mhz Clock
process (clk50_in)
begin
	if clk50_in'event and clk50_in='1' then
	  if (Clk25 = '0')then
	    Clk25 <= '1' after 2 ns;
	  else
	    Clk25 <= '0' after 2 ns;
		end if;
	end if;
end process;		  

process (Clk25)
TYPE Screen_Line1 is ARRAY(0 to 15, 0 to 47) OF std_logic;
 
--CONSTANT char_L1 : Screen_Line1 := (( '0','1','1','1','0','0','0','0','0','0','0','1','0','0','1','0','0','0','0','0','0','1','1','1','0','0','0','1','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'),
--										  		( '1','0','0','0','0','1','0','0','1','0','0','1','0','0','1','0','0','0','0','0','0','1','0','0','1','0','0','1','0','0','0','0','0','0','0','0','1','1','1','1','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'),
--										  		( '1','0','0','0','0','1','0','1','0','0','0','1','0','0','1','0','0','0','0','0','0','1','0','0','1','0','0','1','0','1','0','0','1','0','0','1','0','0','0','0','1','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'),
--										  		( '0','1','1','0','0','1','1','0','0','0','0','0','1','1','1','0','0','0','0','0','0','1','0','0','1','0','0','1','0','1','0','0','1','0','0','1','0','0','0','0','1','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'),
--										  		( '0','0','0','1','0','1','1','0','0','0','0','0','0','0','1','0','0','0','0','0','0','1','1','1','1','0','0','1','0','1','0','0','1','0','0','1','1','1','1','1','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'),
--										  		( '0','0','0','1','0','1','0','1','0','0','0','0','0','0','1','0','0','0','0','0','0','1','0','0','0','1','0','1','0','1','0','0','1','0','0','1','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'),
--										  		( '0','0','0','1','0','1','0','0','1','0','0','0','0','1','0','0','0','0','0','0','0','1','0','0','0','1','0','1','0','0','1','1','1','0','0','0','1','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'),
--										  		( '1','1','1','0','0','1','0','0','0','1','0','1','1','0','0','0','0','0','0','0','0','1','1','1','1','0','0','1','0','0','0','0','0','1','0','0','0','1','1','1','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0') );
												


CONSTANT char_L1 : Screen_Line1 :=(
('0','0','0','0','1','0','0','0','0','0','1','0','0','0','0','0','0','0','0','0','0','0','0','1','0','1','0','0','0','0','0','0','0','0','0','0','0','0','0',
'1','0','0','0','0','0','0','0','0'),

('0','1','1','1','1','1','1','1','0','0','1','1','0','0','0','0','0','0','0','0','0','0','0','1','0','0','1','1','0','0','0','0','0','0','0','0','0','0','0',
'1','0','0','0','1','1','0','0','0'),

('0','0','0','0','1','0','0','0','0','0','1','0','1','0','0','0','0','0','0','0','0','0','0','1','0','0','0','1','0','0','0','0','0','0','1','1','1','1','0',
'1','1','0','1','0','0','0','0','0'),

('1','1','1','1','1','1','1','1','1','1','1','1','1','1','1','0','1','1','1','1','1','1','1','1','1','1','1','1','1','1','1','0','0','0','0','0','0','1','0',
'1','0','1','0','0','0','0','0','0'),

('0','0','0','0','0','0','0','0','0','0','1','0','0','0','0','0','0','0','0','0','0','0','0','1','0','0','0','0','0','0','0','0','0','0','0','0','1','0','0',
'1','0','0','1','1','0','0','0','0'),

('0','1','1','1','1','1','1','1','0','0','1','0','0','0','0','0','0','0','1','0','0','0','0','1','0','0','0','1','1','0','0','0','0','0','1','1','0','1','0',
'1','0','0','0','0','1','1','1','0'),

('0','1','0','0','1','0','0','1','0','0','1','0','1','0','0','0','0','0','0','1','0','0','0','1','0','0','1','0','0','0','0','0','0','0','0','0','0','0','1',
'0','0','0','0','0','0','1','0','0'),

('0','1','1','1','1','1','1','1','0','0','1','0','1','1','0','0','0','0','0','0','1','0','0','1','0','1','0','0','0','0','0','0','0','0','0','0','1','0','0',
'0','0','0','1','0','0','0','0','0'),

('0','1','0','0','1','0','0','1','0','0','1','0','1','0','0','0','0','0','0','0','0','1','0','1','1','1','0','0','0','0','0','0','1','1','1','0','1','0','1',
'1','1','0','1','0','1','1','0','0'),

('0','1','1','1','1','1','1','1','0','0','0','1','1','0','0','0','0','0','0','0','1','0','0','1','0','0','1','0','0','0','0','0','0','0','1','0','1','1','0',
'0','1','0','1','1','0','0','0','0'),

('0','0','0','1','0','0','1','0','0','0','0','1','0','0','0','0','0','0','0','1','0','0','0','1','0','0','0','1','1','0','0','0','0','0','1','0','1','1','0',
'0','1','0','1','0','1','0','0','0'),

('0','1','1','1','1','1','1','1','1','0','0','1','0','0','0','0','0','1','1','0','0','0','0','1','0','0','0','0','1','1','1','0','0','1','0','0','1','0','1',
'0','1','0','1','0','1','0','0','0'),

('0','0','0','1','0','0','1','0','0','0','1','0','1','0','1','0','0','0','0','0','0','0','0','1','0','0','0','0','0','1','0','0','0','1','0','0','1','0','0',
'1','0','0','1','0','0','1','1','0'),

('1','1','1','1','1','1','1','1','1','1','0','0','1','0','1','0','0','0','0','0','0','0','0','1','0','0','0','0','0','0','0','0','1','0','0','0','1','0','1',
'0','0','0','1','0','0','1','0','0'),

('0','0','0','1','0','0','1','0','0','0','0','0','0','1','1','0','0','0','0','0','0','1','0','1','0','0','0','0','0','0','0','0','0','0','1','0','1','0','0',
'0','1','0','1','0','0','0','0','0'),

('0','1','1','0','0','0','0','1','0','0','0','0','0','0','1','0','0','0','0','0','0','0','1','0','0','0','0','0','0','0','0','0','0','0','0','1','0','0','0',
'0','0','1','0','0','0','0','0','0'));

							
variable Line:integer:=0;
variable Pixel:integer:=0;

	begin       --initial the screen
		if Clk25'event and Clk25 = '1' then
			if (Horizontal_Counter >= "0010010000" ) -- 144   why from 144?
			and (Horizontal_Counter < "1100010000" ) -- 784   640+100
			and (Vertical_Counter >= "0000100111" ) -- 39     why from 39?
    		and (Vertical_Counter < "1000000111" ) -- 519     480+39
			then
				Red_out <= '0';
				Green_out <= '0';
				Blue_out <='0';
				-----Line 1	
			  	  if (Horizontal_Counter >=  "0110111000" )--440    640/2-24+144
				  and (Horizontal_Counter <= "0111101000")--	488    640/2+24+144
				  and (Vertical_Counter >=	"0011101000") --232      240-8
				  and (Vertical_Counter <= "0011110111") then -- 247  240+8-1
				  	if(Pixel <= 47) then --Line 1 Lets make our Text WHITE
				  		 Red_out <= char_L1(Line, Pixel);
						 Green_out <= char_L1(Line, Pixel);
						 Blue_out <= char_L1(Line, Pixel);
						 Pixel:= Pixel+1;
				 	 elsif(Pixel >= 48) then  -- All else BLACK
				  		Red_out <= '0';
						Green_out <= '0';
						Blue_out <= '0';
				  	end if;
					end if;
					end if;
			if (Horizontal_Counter > "0000000000" )
      		and (Horizontal_Counter < "0001100001" ) -- 96+1   generate the hs_out and the vs_out
    			then
			  		hs_out <= '0';
    			else
      	  		hs_out <= '1';
    		end if;
			if (Vertical_Counter > "0000000000" )
      		and (Vertical_Counter < "0000000011" ) -- 2+1
    			then
      			vs_out <= '0';
    			else
      			vs_out <= '1';
    		end if;

			Horizontal_Counter <= Horizontal_Counter+"0000000001";
    		if (Horizontal_Counter="1100100000") then    --800? decide the frequency of Hs 50000000/2/800 = 31.25K Hz
      		Vertical_Counter <= Vertical_Counter+"0000000001";
      		Horizontal_Counter <= "0000000000";
				Pixel:= 0;
				if (Vertical_Counter >=	"0011101000") -- First Line  232
				   and (Vertical_Counter <= "0011110111") then     --247  
						if (Line <= 15) then
				  		Line:= Line+1;
						elsif (Line >= 16) then
				 		 Line:= 0;
						end if;
				 end if;
    		end if;
    		if (Vertical_Counter="1000001001") then		--521?  decide the frequency of Hs 50000000/2/800/521 = 59.98 Hz  
      		Vertical_Counter <= "0000000000";
				Line:= 0;
    		end if;
  		end if;
	end process;	 
end Behavioral;