VGA

A Video Graphics Array (VGA) connector is a three-row 15-pin DE-15 connector. The 15-pin VGA connector is found on many video cards, computer monitors, and some high definition television sets. On laptop computers or other small devices, a mini-VGA port is sometimes used in place of the full-sized VGA connector.

Interfacing VGA with FPGA/CPLD UDB

The Spartan-3 Primer board has 3-Bit VGA, indicated as in Figure. As shown in Figure, the Spartan3 FPGA/CPLD UDB controls five VGA signals: Red (R) its 1st pin in connector, Green (G) its 2nd pin, Blue (B) its 3rd pin, Horizontal Sync (HS) 13th pin, and Vertical Sync (VS) its 14th pin, all available on the VGA connector. The FPGA/CPLD pins that drive the VGA port appear in Table. A video controller circuit must be created in the FPGA to drive the sync and color signals with the correct timing in order to produce a working display system.

Pin Assignment with Spartan-3 Primer FPGA/CPLD

Note: Please refer User Manual for Pin number of FPGA/CPLD

Schematics to Interface VGA with FPGA/CPLD UDB

VHDL Code for VGA using FPGA/CPLD UDB

********************************************************************

Title : Program for VGA to LED Display

***********************************************************************

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.STD_LOGIC_ARITH.ALL;

use IEEE.STD_LOGIC_UNSIGNED.ALL;

 

entity VGA is

port(clk50_in : in std_logic;         -----system clock i/p

       red       : out std_logic;         -----primrary colour output

       green     : out std_logic;

       blue     : out std_logic;

       hs_out   : out std_logic;         ------horizontal control signal

       vs_out   : out std_logic);         ------vertical   control signal

end VGA;

 

architecture Behavioral of VGA is

 

signal clk25             : std_logic;

signal hs : std_logic_vector (9 downto 0);

signal vs : std_logic_vector (9 downto 0);

begin

 

-- generate a 25Mhz clock

process (clk50_in)

begin

if clk50_in'event and clk50_in='1' then

if (clk25 = '0') then              

clk25 <= '1';

else

clk25 <= '0';

end if;

end if;

end process;

------display logic for message "PANTECH SOLUTIONS"

process (clk25)

begin

if clk25'event and clk25 = '1' then

if hs = "0011001000" and vs >= "0011001000" and vs <= "0011111010" then ---horizantal and vertical line display constraint

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0011001000" and vs >= "0100101100" and vs <= "0101000101" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0011111010" and vs >= "0011001000" and vs <= "0011100001" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0011111010" and vs >= "0101000101" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0100000100" and vs >= "0011001000" and vs <= "0011111010" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0100000100" and vs >= "0100101100" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0100110110" and vs >= "0011001000" and vs <= "0011111010" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0100110110" and vs >= "0100101100" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0101000000" and vs >= "0011001000" and vs <= "0011111010" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0101000000" and vs >= "0100101100" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0101110010" and vs >= "0011001000" and vs <= "0011111010" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0101111110" and vs >= "0100101100" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0110101110" and vs >= "0100101100" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0110010101" and vs >= "0011001000" and vs <= "0011111010" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0110111000" and vs >= "0011001000" and vs <= "0011111010" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0111010001" and vs >= "0100101100" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "0111110100" and vs >= "0011001000" and vs <= "0011111010" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "1000001101" and vs >= "0100101100" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "1000110000" and vs >= "0011001000" and vs <= "0011111010" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "1001100010" and vs >= "0011001000" and vs <= "0011111010" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "1000110000" and vs >= "0100101100" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "1001100010" and vs >= "0100101100" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "1001101100" and vs >= "0100101100" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

elsif hs = "1010011110" and vs >= "0100101100" and vs <= "0101011110" then

red <= '1' ;

blue <= '0';

green <= '0' ;

--------------------------------------------------------------------------------

else                     ----------blank signal display

red <= '0' ;

blue <= '0';

green <= '0' ;

end if;

if (hs > "0000000000" )

and (hs < "0001100001" ) -- 96+1   -----horizontal tracing

then

hs_out <= '0';

else

hs_out <= '1';

end if;

if (vs > "0000000000" )

and (vs < "0000000011" ) -- 2+1   ------vertical tracing

then

vs_out <= '0';

else

vs_out <= '1';

end if;

hs <= hs + "0000000001" ;

if (hs= "1100100000") then     ----incremental of horizontal line

vs <= vs + "0000000001";       ----incremental of vertical line

hs <= "0000000000";

end if;

if (vs= "1000001001") then                 

vs <= "0000000000";

end if;

end if;

end process;

end Behavioral;

User Constraint File

NET "blue"  LOC = "p26"  ;

NET "clk50_in"  LOC = "p181"  ;

NET "green"  LOC = "p24"  ;

NET "hs_out"  LOC = "p21"  ;

NET "red"  LOC = "p27"  ;

NET "vs_out"  LOC = "p22"