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HDMI to VGA with FPGA ?

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farshadr

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hi every body
i want read from HDMI port and convert in to VGA with fpga device
i dont know anything about HDMI protecol and how its work.
having any idea or useful document ?
 

TrickyDicky

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I guess no one knows - you'll have to do your own research.
 

emresel

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Hi;
You can find see the documents; especially first white paper demystifies the concept.
https://cn.siliconimage.com/docs/SiI-WP-007-A.pdf
https://www.pxisa.org/files/Digital%20test%20for%20video.pdf
On the other hand as you see from the picture datarate on TMDS lines are 10 times of pixel clk (for an 8 bit video content).
i.e. for 1080p video, pixel clk is around 148Mhz, which means you should capture/sample data bits around 1.48Ghz. -Since it is serial and baseband video, not applied any codecs etc.- I am not sure if this can be performed on an FPGA DCMs.


May be you can use this kind of “HDMI receiver IC” as an example.
SiI9223 & 9223 HDMI Receiver
It extracts the video and audio content from the TMDS and puts on a parallel data bus. Then your FPGA speed downs to 148Mhz which should be reasonable for FPGAs.

Goodluck
 

elec4fun

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Hi,

This king of conversion is hardly possible due to the HDCP protection. The HDMI stream is scrambled in order to achieve copy protection.

If you source is not HDCP protected then you could do this conversion in FPGA. The stream can be parallelized using serdes (ALTGX in altera devices).

Regards,
Franck.
 

StephenEcob

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XIlinx have an excellent application note, xapp460. It comes with a free implementation of an HDMI receiver for the Spartan FPGA. Once you've used it to receive an HDMI stream then outputting a VGA equivalent should be reasonably straightforward. You will need an external triple 8 bit DAC chip for the VGA RGB signals, or you could create a cheap and nasty DAC using 24 LVCMOS outputs and a bunch of resistors.

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Regards,
Stephen
 

BlackHelicopter

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Nice, keep the idea's flowing. How about VGA to HDMI or TMDS is that possible?
 
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StephenEcob

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VGA to HDMI is certainly do-able. The first requirement is a high speed triple ADC to convert the VGA colour channels to digital. After that, feed the outputs of the ADCs into an FPGA. XIlinx application note xapp460 includes HDMI output circuitry as well as HDMI in.


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