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DVI - LVDS controller

Hello all,

I am thinking of building a device which will convert DVI output from my graphics card to LVDS to drive my LCD panel. I was originally thinking of using ICs but I wondered if it was possible to do using an fpga?

I have a few general questions regarding using LVDS to drive an lcd panel...

From studying TMDS (DVI signal) and LVDS I have found they are quite

similar. Is it possible to simple translate the 10bits TMDS stream to its 8bit RGB value and then send that out at a slower clock speed over the LVDS interface? If I have this correct, my understanding is DVI works at a much higher frequency than my LCD needs (40MHz). Can i simply 'sample' the DVI signal every 4 clock cycles (if I use the clock/4 from the DVI input), for example? Also the datasheet for my LCD panel indicates it does not specfically have pins for timing information. I have seen chips from National Semiconductors which output LVDS but require vsync and hsync parameters

- I am unsure how this fits into my project - can I not simply send the data to the LCD panel every clock cycle?

Lastly. I am thinking of using a Spartan3 based board (possibly the Raggedstone -

formatting link
to do the conversion. Is this board suitable?

Any advice will be greatly appreciated.

Regards, Kevin

Reply to
helix
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No, you cant use FPGA alone, if you want DVI-LVDS take a TI DVI receiver, chances are that you can connect the display to it almost directly there was an project with free PCB design for this kind of converter but unfortunatly I cant find the link any more.

optionally you may use FPGA *after* the DVI receiver if needed for some reason.

Antti

Reply to
Antti

Thanks for the reply, Antti.

I have seen the TI DVI reciever chip and it seems quite complex. Do you know why this is required? Would it be easier to convert from a VGA signal? I would need ADCs then - I just assumed it would be simpler to convert a signal that's already digital.

Reply to
helix

no

an Analog VGA to digital is almost even more complex, there is almost only chip available for purchasing (ADI sells only for 20K+ year customer) the available chip is Averlogic AL875, but unfortunatly it is missing internal PLL so you need additionally ICS1523 or similar - I have the Averlogic ADC but not the PLL so cant test it - (I have a pending design inquiry for VGA to usb conversion)

the TI chip is actually pretty simple, the board that I was referring too had pretty much only the TI chip and connectors on the board

Antti

Reply to
Antti

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