09-15-2019 12:56 PM
I have been developing a custom HDMI core on Xilinx Artix-7, and with some devices it does not show any video at all or it is very intermittent, but on other devices the signal is solid.
I do NOT currently implement any AVI Infoframes. Could this be the reason? Or should I be more worried about things like phase drift between TMDS lanes?
Any help appreciated.
09-15-2019 01:15 PM
What kind of HDMI do you implement ? HDMI Rx or HDMI Tx ?
If Rx, you must implement DDC/CI and use suitable EDID.
If Tx, you can only output suitable video signal without AVI infoframe.
09-15-2019 02:57 PM
It's HDMI TX. The video content is RGB444 so is the base format for when info frames are not present, but the compatibility is very poor. Do you think no AVI info frames could be the cause?
09-15-2019 06:34 PM
09-23-2019 06:05 AM
If your question is answered or your issue is solved, please kindly mark the response which helped as solution (click on "Accept as solution" button below the reply).
If this is not solved/answered, please reply in the topic giving more information on your current status.
Thanks and Regards,
09-23-2019 06:09 AM
RGB888? Double samples. I dont think we have the bandwidth for that. It was my understanding that RGB444 was the default standard if no AVI Infoframes are present?
09-24-2019 03:01 PM
There are TIPS for you about HDMI.
- HDMI uses TMDS protocol to reduce/minimize DC component.
-> Must use correct encoding/decoding pattern. which known as K code.
- Don't need AVI infoframe, if you don't concern compatibility.
-> Some HDMI signal and pattern generators can turn off AVI infoframe.
-> It is hard to decode TMDS signal without negotiation in HDMI sink side, if you use specific clock frequency and/or specific resolution.
- There is YUV444 as default format. Also, there are YUV422, YUV420, RGB88 and so on.
So, I suspected it's protocol issue...
09-25-2019 12:58 AM
Thanks for your input.
When you say negotiation, I take you are referring to the i2c EDID part of the protocol?