Hello,
Does anyone know where can I find an HDMI core for SPARTAN 6 FPGA?

Search for XAPP495.

You mean to search in this cite (opencores.org) or generally in the internet?

XAPP495 is a Xilinx application note.
Suggest you look on the Xilinx website, if you are using the *XILINX* Spartan-6.

If you are using the Altera Spartan-6, then please ignore my comments :)

Thanks, I'll look into it.

XAPP495 is a start, and works for Digilent Atlys board, but there are a few gotchas.
One of them is that it does not implement EDID (monitor identification data) nor audio, so technically is not HDMI compliant. It is actually a DVI generator, which is compatible with HDMI. Due to lack of EDID, some HDMI monitors and video sources refuse to work with XAPP495, but several monitors/cameras do work.

You can read about that here: http://forums.xilinx.com/t5/Spartan-Family-FPGAs/xapp495-big-problem/td-p/138728

Jonny

1. EDID is not the only possible 'show-stopper' with HDMI or DVI interfaces. HDMI design requires significant effort and attention to many details.

2. EDID is for the benefit of the video source and only the video source. The video display (or 'sink') should not have any dependency on the use (or non-use) of EDID by the video source.

3. The HDMI standard defines some video formats which *all* video sources and video displays (sinks) are required to support. You should not need EDID to source or display video in one of these common denominator video formats.

With all due respect, this is silly. This *incorrectly* suggests some incompatibility in XAPP495. There is a distinction to be made between incompatibility and 'additional stuff left to the designer'.

And as I mentioned in previous post, lack of EDID in a video source would not prevent a connected display from operating. In other words, there is no basis for saying that any HDMI monitor would not work with an XAPP495-based design, simply for lack of EDID.

FWIW I also concur with this statement. EDID data is generated by the sink (eg. monitor) to allow a source to detect the timing/resolutions supported by the sink (monitor). If your sink is designed to drive out a specified resolution, then EDID can be ignored/not implement.

So that said, is there a reason xapp495 won't work with some hdmi tv/monitors? I assume the audio and data periods are optional if there is no audio or data to send. Are the preamble and guard band required for some monitors? Just trying to understand how a monitor I have is able to make the distinction that the signal coming out of xapp495 is in fact DVI.

Suggest you examine *all* the differences between signal sources which work with a specific display and signal sources which do not. I suspect there are more differences than simply "XAPP495" vs. "non-XAPP495".

There are many many things which can go wrong. XAPP495 has been 'out' for a number of years, and I have yet to hear of some clear, documented fundamental incompatibility issue in its design. Your presumption, therefore, should be that the problems you are seeing are likely NOT due to XAPP495 code.