VGA timing

Hi everbody,
I wanna implement VGA core at 1024x768x75Hz (15" LCD Monitor) on
Spartan3E starter kit. I have got a few question. I have tried to find
some detialed documents for VGA timing But I can't. There are 640x480
and 800x600 but there is no document for more resolution and refresh
rate.
- Front porch time, back porch time, and sync pulse times are same at
every resolution (I think it's standard because VGA cards can change
resulation and refresh rate for every value and every monitor??? But
There are different values for 640x480 and 800x600 on the documents???)
- What is hsync and vsync polarisation? What must I do if it's negative
or positive? (invert the sync signal???) Why it is different for
different resolution?
- Any body can give me timing values or recommend any source? ( I can't
a right document on the Vesa web page)

Thanks

On 2006-10-12, icegray@gmail.com <icegray@gmail.com> wrote:
> - Any body can give me timing values or recommend any source? ( I can't
> a right document on the Vesa web page)

If you google for mode line generator you should find some pages that
allow you to specify a resolution and refresh rate and get timing information
in return. These pages are generally intended to create modelines for
XFree86 so you will have to interpret the results yourself though.

/Andreas

On 12 Oct 2006 00:46:41 -0700, icegray@gmail.com wrote:

>Hi everbody,
>I wanna implement VGA core at 1024x768x75Hz (15" LCD Monitor)

If it is always going to be LCD you can probably use 60Hz to reduce bandwidth.

icegray@gmail.com wrote:
> Hi everbody,
> I wanna implement VGA core at 1024x768x75Hz (15" LCD Monitor) on
>...
> - Any body can give me timing values or recommend any source? ( I can't
> a right document on the Vesa web page)

You can try:
   http://www.tkk.fi/Misc/Electronics/faq/vga2rgb/calc.html

Sandro

icegray@gmail.com wrote:
> Hi everbody,
> I wanna implement VGA core at 1024x768x75Hz (15" LCD Monitor) on
> Spartan3E starter kit. I have got a few question. I have tried to find
> some detialed documents for VGA timing But I can't. There are 640x480
> and 800x600 but there is no document for more resolution and refresh
> rate.
> - Front porch time, back porch time, and sync pulse times are same at
> every resolution (I think it's standard because VGA cards can change
> resulation and refresh rate for every value and every monitor??? But
> There are different values for 640x480 and 800x600 on the documents???)
> - What is hsync and vsync polarisation? What must I do if it's negative
> or positive? (invert the sync signal???) Why it is different for
> different resolution?
> - Any body can give me timing values or recommend any source? ( I can't
> a right document on the Vesa web page)
> 
> Thanks

Google "video timing calculator"

icegray@gmail.com writes:

> Hi everbody,

Hi,

> I wanna implement VGA core at 1024x768x75Hz (15" LCD Monitor) on
> Spartan3E starter kit. I have got a few question. I have tried to find
> some detialed documents for VGA timing But I can't. There are 640x480
> and 800x600 but there is no document for more resolution and refresh
> rate.

Googling vga timings gives this as the first hit, which has 1024x768
at the bottom:
http://www.epanorama.net/documents/pc/vga_timing.html
This might also be useful:
http://www.tldp.org/HOWTO/XFree86-Video-Timings-HOWTO/magic.html

Cheers,
Martin

-- 
martin.j.thompson@trw.com 
TRW Conekt - Consultancy in Engineering, Knowledge and Technology
http://www.conekt.net/electronics.html

   

> You can try:
>    http://www.tkk.fi/Misc/Electronics/faq/vga2rgb/calc.html

This calculator is very good. Thanks for it.
Also do you have any idea for polarization???

icegray@gmail.com wrote:
> > You can try:
> >    http://www.tkk.fi/Misc/Electronics/faq/vga2rgb/calc.html
>
> This calculator is very good. Thanks for it.
> Also do you have any idea for polarization???

icegray,
...search and read, search and read.... ;-)

btw:
http://www.tkk.fi/Misc/Electronics/faq/vga2rgb/basics.html

bye
Sandro

icegray@gmail.com wrote:
> Hi everbody,
> I wanna implement VGA core at 1024x768x75Hz (15" LCD Monitor) on
> Spartan3E starter kit. I have got a few question. I have tried to find
> some detialed documents for VGA timing But I can't. There are 640x480
> and 800x600 but there is no document for more resolution and refresh
> rate.
> - Front porch time, back porch time, and sync pulse times are same at
> every resolution (I think it's standard because VGA cards can change
> resulation and refresh rate for every value and every monitor??? But
> There are different values for 640x480 and 800x600 on the documents???)
> - What is hsync and vsync polarisation? What must I do if it's negative
> or positive? (invert the sync signal???) Why it is different for
> different resolution?
> - Any body can give me timing values or recommend any source? ( I can't
> a right document on the Vesa web page)
> 
> Thanks
> 

I know this doesn't answer the question exactly, but here are the 
parameters I used in my VGA controller for a 60Hz refresh rate:

     "1024x768_60Hz": // pixel clk 65MHz
       begin
                           H_FRONT_PORCH=24;   HSYNC_WIDTH=136;
         H_BACK_PORCH=160; LEFT_BORDER=0;      LINE_WIDTH=1024;
         RIGHT_BORDER=0;   V_FRONT_PORCH=3;    VSYNC_WIDTH=6;
         V_BACK_PORCH=29;  TOP_BORDER=0;       FRAME_HEIGHT=768;
         BOTTOM_BORDER=0;  SYNC_POLARITY=0;
       end

You can probably use the same parameters but just bump up the pixel 
clock frequency to 80MHz or so.
-Kevin

icegray@gmail.com wrote:

> Also do you have any idea for polarization???

At a certain point you just need to try and see what the result is.
When you get close, you can probably figure out the error from the sort
of distortion you see.

Also most modern monitors (and all LCD's) do a lot of interpretation of
the incoming signal, so things like polarity are likely either
autodetected or available in a settings menu.  (Though depending on how
the on screen display is done, you may not be able to see the settings
menu if you have an input signal that is close enough to be recognized
as a signal, but not good enough to produce a stable picture.)