[HDMI] Question with TMDS signal

Kyoung Keun Lee

Hello,

I have a question with HDMI Interface, especially with TMDS signal as I mentioned in the title.

Customer notice that our product has a failure with monitor pattern noise.

We analyzed the product and found that our main board's HDMI connector wasn't suit well, It means that HDMI connector one pin for TMDS1+ was open.

From the Desktop, the product which was issued work well. There isn't any noise from the pattern.

From the customer system, the product happened with the problem.

I have questions with these symptom.

1. TMDS 1+ Channel is open, but the monitor is working well with the desktop. Is there any recovery action from the graphic card to the problem signal? Why the monitor work well from desktop?

2. There is a difference with two test methods. What makes the result different? Absolutely, the graphic card makes the difference?

Thanks

over 4 years ago

0 David (ASIC) Liu over 4 years ago

TI__Guru**** 176811 points

Hi,

Which TMDS part are you using?

Is this a source or a sink design?

Thanks

David

0 Kyoung Keun Lee over 4 years ago in reply to David (ASIC) Liu

Prodigy 10 points

Hi, David.

Actually, there is no specific IC (TMDS Part). I just wonder that TMDS 1+ signal open status could impact on the monitor.

Thanks,

Kyoung Keun.

0 David (ASIC) Liu over 4 years ago in reply to Kyoung Keun Lee

TI__Guru**** 176811 points

Kyoung Keun

I honestly don't know, it would depend on the monitor RX. Some RX may be ok with only the data on TMDS1- while other RX needs to see data on both the TMDS1+ and TMDS1-.

Thanks

David

Interface

Interface forum

[HDMI] Question with TMDS signal