Scanning Electron Beam Deflection Yoke Electron Gun

Grid

Phosphor Screen

Blue

Electron Guns
Red Green

Metal Mask

R B R G

B R B

G B G

R G R

B R B

G B G

R G R B

Phosphor Dots on Glass Face Plate

Glass Face Plate

Figure 10.1 Color CRT and Phosphor Dots on Face of Display.

640 Pixels in a row 0,0 639,0

480 Horizontal Scan Lines and Retrace

480 Pixels in a column

0,479

639,479

Figure 10.2 VGA Image - 640 by 480 Pixel Layout.

480 Horizontal Refresh Cycles Red, Green, Blue P i x e l D a ta Vertical Sync 64 s 16.6 ms

1.02 ms

15.24 ms

0.35 ms

Figure 10.3 Vertical Sync Signal Timing.

R ed, Green, B lu e P i xe l D a ta Horizontal Sync 3.77s

1.89 s

25.17 s

0.94 s

31.77 s

Figure 10.4 Horizontal Sync Signal Timing.

25 M hz C lo c k

S y n c G e n e r a tio n C o u n te rs R ow C ol

H o r iz o n t a l S ync V e r t ic a l S ync

D a ta fr o m D e s ig n

V G A S ig n a ls
P ix e l R A M o r C h a ra c te r G e n e ra to r R O M R G B

Figure 10.5 CLPD based generation of VGA Video Signals.

VGA_SYNC clock_48Mhz red green blue red_out green_out blue_out horiz_sync_out vert_sync_out video_on pixel_clock pixel_row[9..0] pixel_column[9..0] inst

UP3core VGA_SYNC

LIBRARY IEEE; USE IEEE.STD_LOGIC_1164.ALL; USE IEEE.STD_LOGIC_ARITH.ALL; USE IEEE.STD_LOGIC_UNSIGNED.ALL; ENTITY VGA_SYNC IS PORT( clock_25Mhz, red, green, blue red_out, green_out, blue_out horiz_sync_out, vert_sync_out pixel_row, pixel_column END VGA_SYNC;

: IN : OUT : OUT : OUT

STD_LOGIC; STD_LOGIC; STD_LOGIC; STD_LOGIC_VECTOR( 9 DOWNTO 0 ));

ARCHITECTURE a OF VGA_SYNC IS : STD_LOGIC; SIGNAL horiz_sync, vert_sync SIGNAL video_on, video_on_v, video_on_h : STD_LOGIC; : STD_LOGIC_VECTOR( 9 DOWNTO 0 ); SIGNAL h_count, v_count BEGIN -- video_on is High only when RGB data is displayed video_on <= video_on_H AND video_on_V;

PROCESS BEGIN WAIT UNTIL( clock_25Mhz'EVENT ) AND ( clock_25Mhz = '1' );

--Generate Horizontal and Vertical Timing Signals for Video Signal -- H_count counts pixels (640 + extra time for sync signals) --- Horiz_sync -------------------------------------------________--------- H_count 0 640 659 755 799 -IF ( h_count = 799 ) THEN h_count <= "0000000000"; ELSE h_count <= h_count + 1; END IF; --Generate Horizontal Sync Signal using H_count IF ( h_count <= 755 ) AND (h_count => 659 ) THEN horiz_sync <= '0'; ELSE horiz_sync <= '1'; END IF;

--V_count counts rows of pixels (480 + extra time for sync signals) --- Vert_sync ----------------------------------------_______------------- V_count 0 480 493-494 524 -IF ( v_count >= 524 ) AND ( h_count => 699 ) THEN v_count <= "0000000000"; ELSIF ( h_count = 699 ) THEN v_count <= v_count + 1; END IF; -- Generate Vertical Sync Signal using V_count IF ( v_count <= 494 ) AND ( v_count = >493 ) THEN vert_sync <= '0'; ELSE vert_sync <= '1'; END IF;

-- Generate Video on Screen Signals for Pixel Data IF ( h_count <= 639 ) THEN video_on_h <= '1'; pixel_column <= h_count; ELSE video_on_h <= '0'; END IF; IF ( v_count <= 479 ) THEN video_on_v <= '1'; pixel_row <= v_count; ELSE video_on_v <= '0'; END IF; -- Put all video signals through DFFs to eliminate -- any delays that can cause a blurry image -- Turn off RGB outputs when outside video display area red_out <= red AND video_on; green_out <= green AND video_on; blue_out <= blue AND video_on; horiz_sync_out <= horiz_sync; vert_sync_out <= vert_sync; END PROCESS; END a;

VGA_SYNC

C lock_48M hz P BSW ITC H 4

INPUT VCC INPUT VCC

clock_48Mhz
red
green
blue

red_out
green_out
blue_out
horiz_sync_out
vert_sync_out
video_on
pixel_clock
pixel_row[9..0]
pixel_column[9..0]

OUTPUT
OUTPUT
OUTPUT

OUTPUT
OUTPUT

VGA_R ed VGA_Green VGA_Blue VGA_H Sync VGA_VSync

GND 11

Video LED Design Example

VGA_SYNC Clock_48Mhz
INPUT VCC

clock_48Mhz red green blue

red_out green_out blue_out horiz_sync_out vert_sync_out video_on pixel_clock

OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT

VGA_Red VGA_Green VGA_Blue VGA_HSync VGA_VSync

Pixel_column[5] Pixel_column[6] Pixel_column[7] 1

Pixel_row[9..0]

pixel_row[9..0] pixel_column[9..0] Pixel_column[9..0]

Video Color Bar Design Example

Address 000001000 : 000001001 : 000001010 : 000001011 : 000001100 : 000001101 : 000001110 : 000001111 :

Font Data 00011000 ; 00111100 ; 01100110 ; 01111110 ; 01100110 ; 01100110 ; 01100110 ; 00000000 ;

Figure 10.6 Font Memory Data for the Character "A".

8 by 8 Font Pixel Data Character Address 000001 for A

Character Generation ROM

Font Row Address 000...111

8 8-bit words per character

Figure 10.7 Accessing a Character Font Using a ROM.

Char_ROM clock character_address[5..0] f ont_row[2..0] f ont_col[2..0] rom_mux_output

inst

UP3core CHAR_ROM

LIBRARY IEEE; USE IEEE.STD_LOGIC_1164.ALL; USE IEEE.STD_LOGIC_ARITH.ALL; USE IEEE.STD_LOGIC_UNSIGNED.ALL; LIBRARY lpm; USE lpm.lpm_components.ALL; ENTITY Char_ROM IS character_address PORT( font_row, font_col rom_mux_output END Char_ROM;

: IN : IN : OUT

STD_LOGIC_VECTOR( 5 DOWNTO 0 ); STD_LOGIC_VECTOR( 2 DOWNTO 0 ); STD_LOGIC);

ARCHITECTURE a OF Char_ROM IS : STD_LOGIC_VECTOR( 7 DOWNTO 0 ); SIGNAL rom_data : STD_LOGIC_VECTOR( 8 DOWNTO 0 ); SIGNAL rom_address BEGIN -- Small 8 by 8 Character Generator ROM for Video Display -- Each character is 8 8-bit words of pixel data char_gen_rom: lpm_rom GENERIC MAP ( lpm_widthad => 9, lpm_numwords => "512", lpm_outdata => "UNREGISTERED", lpm_address_control => "UNREGISTERED", -- Reads in mif file for character generator font data lpm_file => "tcgrom.mif", lpm_width => 8) PORT MAP ( address => rom_address, q = > rom_data); rom_address <= character_address & font_row; -- Mux to pick off correct rom data bit from 8-bit word -- for on screen character generation rom_mux_output <= rom_data ( (CONV_INTEGER( NOT font_col( 2 DOWNTO 0 ))) ); END a;

Table 10.1 Character Address Map for 8 by 8 Font ROM. CHAR ADDRESS CHAR ADDRESS CHAR ADDRESS CHAR ADDRESS

@ A B C D E F G H I J K L M N O

00 01 02 03 04 05 06 07 10 11 12 13 14 15 16 17

P Q R S T U V W X Y Z [
Dn Arrow

]
Up Arrow Lft Arrow

20 21 22 23 24 25 26 27 30 31 32 33 34 35 36 37

Space ! " # $ % & ( ) * + , . /

40 41 42 43 44 45 46 47 50 51 52 53 54 55 56 57

0 1 2 3 4 5 6 7 8 9 A B C D E F

60 61 62 63 64 65 66 67 70 71 72 73 74 75 76 77

VGA_SYNC

Clock_48Mhz
VCC

INPUT VCC

clock_48Mhz
red
green
blue

red_out
green_out
blue_out
horiz_sync_out
vert_sync_out
video_on
pixel_clock
pixel_row[9..0]
pixel_column[9..0]

OUTPUT
OUTPUT
OUTPUT

VGA_Red
VGA_Green
VGA_Blue

OUTPUT
OUTPUT

VGA_HSync
VGA_VSync

Pixel_row[9..0]

Pixel_column[9..0]

Char_ROM

clock
Pixel_row[9..4]
Pixel_row[3..1]
Pixel_column[3..1]

rom_mux_output

character_address[5..0]
f ont_row[2..0]
f ont_col[2..0]

inst

Character Test Design Example

Figure 10.8 MIPS Computer Video Output.

-- Character Format ROM for Video Display -- Displays constant format character data -- on left side of Display area format_rom: lpm_rom GENERIC MAP ( lpm_widthad lpm_numwords lpm_outdata lpm_address_control lpm_file lpm_width

=> 6, =>"60", => "UNREGISTERED", => "UNREGISTERED", -- Reads in mif file for data display titles =>"format.mif", => 6)

Horizontal Sync Counter 639 Compute New RGB Data

799

Displaying RGB Data

479 599 Vertical Sync Counter

Figure 10.10 Bouncing Ball Video Output.

ENTITY ball IS PORT( : OUT STD_LOGIC; SIGNAL Red, Green, Blue : IN STD_LOGIC; SIGNAL vert_sync_out SIGNAL pixel_row, pixel_column : IN STD_LOGIC_VECTOR( 9 DOWNTO 0 )); END ball; ARCHITECTURE behavior OF ball IS -- Video Display Signals SIGNAL reset, Ball_on, Direction : STD_LOGIC; : STD_LOGIC_VECTOR( 9 DOWNTO 0 ); SIGNAL Size : STD_LOGIC_VECTOR( 10 DOWNTO 0 ); SIGNAL Ball_Y_motion SIGNAL Ball_Y_pos, Ball_X_pos : STD_LOGIC_VECTOR( 10 DOWNTO 0 ); -- Size of Ball BEGIN Size <= CONV_STD_LOGIC_VECTOR (8,10 ); -- Ball center X address Ball_X_pos <= CONV_STD_LOGIC_VECTOR( 320,11 ); -- Colors for pixel data on video signal Red <= '1'; -- Turn off Green and Blue to make -- color Red when displaying ball Green <= NOT Ball_on; Blue <= NOT Ball_on;

RGB_Display: PROCESS ( Ball_X_pos, Ball_Y_pos, pixel_column, pixel_row, Size ) BEGIN -- Set Ball_on = '1' to display ball <= pixel_column + Size ) AND IF ( Ball_X_pos ( Ball_X_pos + Size >= pixel_column ) AND ( Ball_Y_pos <= pixel_row + Size ) AND ( Ball_Y_pos + Size >= pixel_row ) THEN Ball_on <= '1'; ELSE Ball_on <= '0'; END IF; END PROCESS RGB_Display; Move_Ball: PROCESS BEGIN -- Move ball once every vertical sync WAIT UNTIL Vert_sync'EVENT AND Vert_sync = '1'; -- Bounce off top or bottom of screen IF Ball_Y_pos >= 480 - Size THEN Ball_Y_motion <= - CONV_STD_LOGIC_VECTOR(2,11); ELSIF Ball_Y_pos <= Size THEN Ball_Y_motion <= CONV_STD_LOGIC_VECTOR(2,11); END IF; -- Compute next ball Y position Ball_Y_pos <= Ball_Y_pos + Ball_Y_motion; END PROCESS Move_Ball; END behavior;