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

Reply to
icegray
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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

Reply to
Andreas Ehliar

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

Reply to
Mike Harrison

You can try:

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Sandro

Reply to
Sandro

Google "video timing calculator"

Reply to
Marlboro

Hi,

Googling vga timings gives this as the first hit, which has 1024x768 at the bottom:

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This might also be useful:
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Cheers, Martin

--
martin.j.thompson@trw.com 
TRW Conekt - Consultancy in Engineering, Knowledge and Technology
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Reply to
Martin Thompson

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

Reply to
icegray

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

btw:

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bye Sandro

Reply to
Sandro

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

Reply to
Kevin Neilson

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.)

Reply to
cs_posting

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