HDMI input

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  • 4 weeks later...



I'd love to know if there is any status update since september? Is the correct place to track it at http://hamsterworks.co.nz/mediawiki/index.php/HDMI_Input ?


What is the easiest way to get a PCB board these days? I'd love to port our HDMI2USB firmware to the Papilio board. The HDMI code has it origin in the NeTV base, but I'm hoping to eventually replace the XAPP code with the awesome stuff you are doing.


Keep up the awesome work!


Tim 'mithro' Ansell

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Hi Tim,


Since it looks like anything approaching 720p @60Hz isn't going to work the design won't meet my original needs and the design has stalled. I've yet to make a serious attempt at EDID support, but it shouldn't be too hard to implement. 


But what I'm really waiting for my Scarab miniSpartan6+ to arrive. It has both HDMI in and out, and the signal path should give much cleaner signals, and allow 24bit pixels end to end.


I am more than happy to make you (or anyone) up a board and post them - the TMDS stuff is stable enough to be useful at 640x480 or maybe 800x600 (or higher at lower frame rates).



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Do you know what is causing the issues with your current design? It sounds like you are suggesting it is an issue with the trace length (or cross talk) on the Papilio board to the header?


The addition of a cheap buffer can go a long way to making HDMI reception easier as they clean up the signal significantly. 


Do you have access to high speed oscilloscope for viewing the signal?

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I don't have any access to high-speed scope, but here is my understanding of my problem...

        + 3.3V      |    50 Ohm                                           +      |                                              |\------+---- Pin connector --- header --- pcb trace --++\                                                     |  \      + 3.3V                                         |   \      |                                              |FPGA+---    50 Ohm                                           |   /      |                                              |  /------+---- Pin connector --- header --- pcb trace --+-/                                                     |/                                                     +

The 50 ohm should be 'close' to the FPGA as possible - at lower speed the 'stub' from the resistor into the FPGA is small enough that reception is fine. At higher speeds I suspect that two traces to the FPGA are acting like capacitors, giving some inter-symbol issues (only a few 8b/10b codes get corrupted - the one with long runs of 1s or 0s).


It is definitely achievable if you design the PCB from scratch to support the high speed interface, but not if you are trying to retrofit it to a board that wasn't designed to support HDMI.

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I just haven't had time to follow this project. I guess you're using the gtp transceivers? At work we use the xilinx ibert core to qualify the signal integrity. I've only used it on gtx and gth not sure about gtp or if it requires an expensive licence.

perhaps i can build you a core but perhaps it is runtime licensed.

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  • 1 year later...

Thank you very much for this project. I've been wanting to try and receive some kind of low-res digital video signal, say 640x480, for a while.

For some (misguided) reason I started by reading the DisplayPort standard, but I quickly realized it's waaay too complex for my abilities. :blink: Compared to it, HDMI / DVI-D seems a piece of cake. I mean, It even comes with its own clock line! Actually I never knew HDMI was just DVI-D repackaged. That's quite sleazy of them.

I don't have a Papilion (yet). Would you strongly recommend using an FPGA with builtin support for TMDS? Said another way, what kind of circuit would I need to hook the TMDS pairs to a simple CPLD, or maybe to a Cyclone IV? (which is what I have atm.*) I don't have any experience with differential transmission lines, so if it's more complicated than a few components, I'll just get a Papilion.

Finally, I couldn't find the schematics for your wing board on your wiki, could you please send me a copy? Even if it's just a sketch or a screenshot, I'm a beginner and every bit helps :P

* Cyclone IV datasheet says "Differential I/O: SSTL, HSTL, LVPECL, BLVDS, LVDS, mini-LVDS, RSDS, and PPDS" but I don't have a clue whether any of them are physically compatible with TMDS! :unsure:

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  • 2 years later...
On 2014. 9. 4. at 11:57 AM, hamster said:



Dear Hamster,

If you don't mind, Can I buy your spare PCBs of wings? or Can you send me hdmi pcb file?



>I attempted to build three wings last night for those who asked. Here they are prior to reflow




My HDMI connector reflow skills are lacking. I put the line of solder paste in the wrong place and I ended up with solder bridges trapped under the connector. I might have slavaged two with a little solder wick. Will update as when I get a chance to go over the boards with my meter.



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  • 2 weeks later...

Hello Carter Lee, 

I don't think that Hamster has any of these HDMI Wings available yet. But I have a newer version available that I can send to you, as long as you don't mind any documentation or support... If that is ok then send us an email with your shipping information at support@gadgetfactory.net




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