Subversion Repositories z80soc

library IEEE;

use  IEEE.STD_LOGIC_1164.all;

use  IEEE.STD_LOGIC_ARITH.all;

use  IEEE.STD_LOGIC_UNSIGNED.all;

-- Module Generates Video Sync Signals for Video Montor Interface

-- RGB and Sync outputs tie directly to monitor conector pins

ENTITY VGA_SYNC IS

        PORT(   clock_25Mhz                                                     : IN    STD_LOGIC;

                        red, green, blue                                        : IN    STD_LOGIC_VECTOR(3 DOWNTO 0);

                        red_out, green_out, blue_out            : OUT   STD_LOGIC_VECTOR(3 DOWNTO 0);

                        horiz_sync_out, vert_sync_out,

                        video_on, pixel_clock                           : OUT   STD_LOGIC;

                        pixel_row, pixel_column                         : OUT   STD_LOGIC_VECTOR(9 DOWNTO 0));

END VGA_SYNC;

ARCHITECTURE a OF VGA_SYNC IS

        SIGNAL horiz_sync, vert_sync : STD_LOGIC;

        SIGNAL video_on_int, video_on_v, video_on_h : STD_LOGIC;

        SIGNAL h_count, v_count :STD_LOGIC_VECTOR(9 DOWNTO 0);

--

-- To select a different screen resolution, clock rate, and refresh rate

-- pick a set of new video timing constant values from table at end of code section

-- enter eight new sync timing constants below and

-- adjust PLL frequency output to pixel clock rate from table

-- using MegaWizard to edit video_PLL.vhd

-- Horizontal Timing Constants  

        CONSTANT H_pixels_across:       Natural := 640;

        CONSTANT H_sync_low:            Natural := 664;

        CONSTANT H_sync_high:           Natural := 760;

        CONSTANT H_end_count:           Natural := 800;

-- Vertical Timing Constants

        CONSTANT V_pixels_down:         Natural := 480;

        CONSTANT V_sync_low:            Natural := 491;

        CONSTANT V_sync_high:           Natural := 493;

        CONSTANT V_end_count:           Natural := 525;

BEGIN

-- video_on is high only when RGB pixel data is being displayed

-- used to blank color signals at screen edges during retrace

video_on_int <= video_on_H AND video_on_V;

-- output pixel clock and video on for external user logic

pixel_clock <= clock_25Mhz;

video_on <= video_on_int;

PROCESS

BEGIN

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

--Generate Horizontal and Vertical Timing Signals for Video Signal

-- H_count counts pixels (#pixels across + extra time for sync signals)

-- 

--  Horiz_sync  ------------------------------------__________--------

--  H_count     0                 #pixels            sync low      end

--

        IF (h_count = H_end_count) THEN

                h_count <= "0000000000";

        ELSE

                h_count <= h_count + 1;

        END IF;

--Generate Horizontal Sync Signal using H_count

        IF (h_count <= H_sync_high) AND (h_count >= H_sync_low) THEN

                horiz_sync <= '0';

        ELSE

                horiz_sync <= '1';

        END IF;

--V_count counts rows of pixels (#pixel rows down + extra time for V sync signal)

--  

--  Vert_sync      -----------------------------------------------_______------------

--  V_count         0                        last pixel row      V sync low       end

--

        IF (v_count >= V_end_count) AND (h_count >= H_sync_low) THEN

                v_count <= "0000000000";

        ELSIF (h_count = H_sync_low) THEN

                v_count <= v_count + 1;

        END IF;

-- Generate Vertical Sync Signal using V_count

        IF (v_count <= V_sync_high) AND (v_count >= V_sync_low) THEN

                vert_sync <= '0';

        ELSE

                vert_sync <= '1';

        END IF;

-- Generate Video on Screen Signals for Pixel Data

-- Video on = 1 indicates pixel are being displayed

-- Video on = 0 retrace - user logic can update pixel

-- memory without needing to read memory for display

        IF (h_count < H_pixels_across) THEN

                video_on_h <= '1';

                pixel_column <= h_count;

        ELSE

                video_on_h <= '0';

        END IF;

        IF (v_count <= V_pixels_down) THEN

                video_on_v <= '1';

                pixel_row <= v_count;

        ELSE

                video_on_v <= '0';

        END IF;

-- Put all video signals through DFFs to elminate any small timing delays that cause a blurry image

                horiz_sync_out <= horiz_sync;

                vert_sync_out <= vert_sync;

                red_out <= red AND video_on_int & video_on_int & video_on_int & video_on_int;

                green_out <= green AND video_on_int & video_on_int & video_on_int & video_on_int;

                blue_out <= blue AND video_on_int & video_on_int & video_on_int & video_on_int;

END PROCESS;

END a;

--

-- Common Video Modes - pixel clock and sync counter values

--

--  Mode       Refresh  Hor. Sync    Pixel clock  Interlaced?  VESA?

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

--  640x480     60Hz      31.5khz     25.175Mhz       No         No

--  640x480     63Hz      32.8khz     28.322Mhz       No         No

--  640x480     70Hz      36.5khz     31.5Mhz         No         No

--  640x480     72Hz      37.9khz     31.5Mhz         No        Yes

--  800x600     56Hz      35.1khz     36.0Mhz         No        Yes

--  800x600     56Hz      35.4khz     36.0Mhz         No         No

--  800x600     60Hz      37.9khz     40.0Mhz         No        Yes

--  800x600     60Hz      37.9khz     40.0Mhz         No         No

--  800x600     72Hz      48.0khz     50.0Mhz         No        Yes

--  1024x768    60Hz      48.4khz     65.0Mhz         No        Yes

--  1024x768    60Hz      48.4khz     62.0Mhz         No         No

--  1024x768    70Hz      56.5khz     75.0Mhz         No        Yes

--  1024x768    70Hz      56.25khz    72.0Mhz         No         No

--  1024x768    76Hz      62.5khz     85.0Mhz         No         No

--  1280x1024   59Hz      63.6khz    110.0Mhz         No         No

--  1280x1024   61Hz      64.24khz   110.0Mhz         No         No

--  1280x1024   74Hz      78.85khz   135.0Mhz         No         No

--

-- Pixel clock within 5% works on most monitors.

-- Faster clocks produce higher refresh rates at the same resolution on

-- most new monitors up to the maximum rate.

-- Some older monitors may not support higher refresh rates

-- or may only sync at specific refresh rates - VESA modes most common.

-- Pixel clock within 5% works on most old monitors.

-- Refresh rates below 60Hz will have some flicker.

-- Bad values such as very high refresh rates may damage some monitors

-- that do not support faster refreseh rates - check monitor specs.

--

-- Small adjustments to the sync low count ranges can be used to move

-- video image left, right (H), down or up (V) on the monitor

--

--

-- 640x480@60Hz Non-Interlaced mode

-- Horizontal Sync = 31.5kHz

-- Timing: H=(0.95us, 3.81us, 1.59us), V=(0.35ms, 0.064ms, 1.02ms)

--

--                clock     horizontal timing         vertical timing      flags

--             Mhz    pix.col low  high end    pix.rows low  high end

--640x480    25.175     640  664   760  800        480  491   493  525

--                              <->                        <->    

--  sync pulses: Horiz----------___------   Vert-----------___-------

--

-- Alternate 640x480@60Hz Non-Interlaced mode

-- Horizontal Sync = 31.5kHz

-- Timing: H=(1.27us, 3.81us, 1.27us) V=(0.32ms, 0.06ms, 1.05ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--640x480      25.175  640  672  768  800    480  490  492  525

--

--

-- 640x480@63Hz Non-Interlaced mode (non-standard)

-- Horizontal Sync = 32.8kHz

-- Timing: H=(1.41us, 1.41us, 5.08us) V=(0.24ms, 0.092ms, 0.92ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--640x480      28.322  640  680  720  864    480  488  491  521

--

--

-- 640x480@70Hz Non-Interlaced mode (non-standard)

-- Horizontal Sync = 36.5kHz

-- Timing: H=(1.27us, 1.27us, 4.57us) V=(0.22ms, 0.082ms, 0.82ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--640x480      31.5    640  680  720  864    480  488  491  521

--

--

-- VESA 640x480@72Hz Non-Interlaced mode

-- Horizontal Sync = 37.9kHz

-- Timing: H=(0.76us, 1.27us, 4.06us) V=(0.24ms, 0.079ms, 0.74ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--640x480      31.5    640  664  704  832    480  489  492  520

--

--

-- VESA 800x600@56Hz Non-Interlaced mode

-- Horizontal Sync = 35.1kHz

-- Timing: H=(0.67us, 2.00us, 3.56us) V=(0.03ms, 0.063ms, 0.70ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--800x600      36      800  824  896 1024    600  601  603  625

--

--

-- Alternate 800x600@56Hz Non-Interlaced mode

-- Horizontal Sync = 35.4kHz

-- Timing: H=(0.89us, 4.00us, 1.11us) V=(0.11ms, 0.057ms, 0.79ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--800x600      36      800  832  976 1016    600  604  606  634

--

--

-- VESA 800x600@60Hz Non-Interlaced mode

-- Horizontal Sync = 37.9kHz

-- Timing: H=(1.00us, 3.20us, 2.20us) V=(0.03ms, 0.106ms, 0.61ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--800x600      40      800  840  968 1056    600  601  605  628 +hsync +vsync

--

--

-- Alternate 800x600@60Hz Non-Interlaced mode

-- Horizontal Sync = 37.9kHz

-- Timing: H=(1.20us, 3.80us, 1.40us) V=(0.13ms, 0.053ms, 0.69ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--800x600      40      800 848 1000 1056     600  605  607  633

--

--

-- VESA 800x600@72Hz Non-Interlaced mode

-- Horizontal Sync = 48kHz

-- Timing: H=(1.12us, 2.40us, 1.28us) V=(0.77ms, 0.13ms, 0.48ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--800x600      50      800  856  976 1040    600  637  643  666  +hsync +vsync

--

--

-- VESA 1024x768@60Hz Non-Interlaced mode

-- Horizontal Sync = 48.4kHz

-- Timing: H=(0.12us, 2.22us, 2.58us) V=(0.06ms, 0.12ms, 0.60ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--1024x768     65     1024 1032 1176 1344    768  771  777  806 -hsync -vsync

--

--

-- 1024x768@60Hz Non-Interlaced mode (non-standard dot-clock)

-- Horizontal Sync = 48.4kHz

-- Timing: H=(0.65us, 2.84us, 0.65us) V=(0.12ms, 0.041ms, 0.66ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--1024x768     62     1024 1064 1240 1280   768  774  776  808

--

--

-- VESA 1024x768@70Hz Non-Interlaced mode

-- Horizontal Sync=56.5kHz

-- Timing: H=(0.32us, 1.81us, 1.92us) V=(0.05ms, 0.14ms, 0.51ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--1024x768     75     1024 1048 1184 1328    768  771  777  806 -hsync -vsync

--

--

-- 1024x768@70Hz Non-Interlaced mode (non-standard dot-clock)

-- Horizontal Sync=56.25kHz

-- Timing: H=(0.44us, 1.89us, 1.22us) V=(0.036ms, 0.11ms, 0.53ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--1024x768     72     1024 1056 1192 1280    768  770  776  806   -hsync -vsync

--

--

-- 1024x768@76Hz Non-Interlaced mode

-- Horizontal Sync=62.5kHz

-- Timing: H=(0.09us, 1.41us, 2.45us) V=(0.09ms, 0.048ms, 0.62ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--1024x768     85     1024 1032 1152 1360    768  784  787  823

--

--

-- 1280x1024@59Hz Non-Interlaced mode (non-standard)

-- Horizontal Sync=63.6kHz

-- Timing: H=(0.36us, 1.45us, 2.25us) V=(0.08ms, 0.11ms, 0.65ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--1280x1024   110     1280 1320 1480 1728   1024 1029 1036 1077

--

--

-- 1280x1024@61Hz, Non-Interlaced mode

-- Horizontal Sync=64.25kHz

-- Timing: H=(0.44us, 1.67us, 1.82us) V=(0.02ms, 0.05ms, 0.41ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--1280x1024   110     1280 1328 1512 1712   1024 1025 1028 1054

--

--

-- 1280x1024@74Hz, Non-Interlaced mode

-- Horizontal Sync=78.85kHz

-- Timing: H=(0.24us, 1.07us, 1.90us) V=(0.04ms, 0.04ms, 0.43ms)

--

-- name        clock   horizontal timing     vertical timing      flags

--1280x1024   135     1280 1312 1456 1712   1024 1027 1030 1064

--

--      VGA female connector: 15 pin small "D" connector

--                   _________________________

--                   \   5   4   3   2   1   /

--                    \   10  X   8   7   6 /

--                     \ 15  14  13 12  11 /

--                      \_________________/

--   Signal Name    Pin Number   Notes

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

--   RED video          1        Analog signal, around 0.7 volt, peak-to-peak  75 ohm 

--   GREEN video        2        Analog signal, sround 0.7 volt, peak-to-peak  75 ohm 

--   BLUE video         3        Analog signal, around 0.7 volt, peak-to-peak  75 ohm

--   Monitor ID #2      4        

--   Digital Ground     5        Ground for the video system.

--   RED ground         6  \     The RGB color video signals each have a separate

--   GREEN ground       7  |     ground connection.  

--   BLUE ground        8  /      

--   KEY                9        (X = Not present)

--   SYNC ground       10        TTL return for the SYNC lines.

--   Monitor ID #0     11        

--   Monitor ID #1     12        

--   Horizontal Sync   13        Digital levels (0 to 5 volts, TTL output)

--   Vertical Sync     14        Digital levels (0 to 5 volts, TTL output)

--   Not Connected     15        (Not used)

--