HDMI issue in DM8168 design

Swapnil Kanani

We are facing HMDI issue with one of our Netra design.

Issue: HDMI demo is working on DM8168 EVM and not working on our Video Server Mother board hardware. We have tested all the demos available in DVR RDK release 01.01.00.04.

Below are the non compliance items from hardware perspective in VSMB from datasheet guidelines

1) 1) Single ended impedance of 60E is not maintained for 4 differential lines of HDMI from processor to ESD device..

2) 2) Between ESD device and HDMI connector thicker traces are used to absorb more ESD energy, in doing so we have not maintained 100E differential and 60E single ended impedance for 4 differential lines of HDMI.

Please confirm whether above deviations can cause problem in proper functioning of on chip HDMI on Netra(DM8167) and integra (C6A8167). We are not observing any activity on any of the 4 differential lines or HDMI_SCL or HDMI_SDA.

over 13 years ago

0 Steve Clynes over 13 years ago

TI__Mastermind 43875 points

I would not expect these differences to cause the complete failure of the HDMI interface. They might cause compliance issues, but not likely a complete failure.

If you are not seeing ANY activity on the differential data/clock lines then this is something more critical than trace impedance matching causing the issue.

Can you post your HDMI portion of your schematics please?

BR,

Steve

0 K Md Feroz Irfan over 13 years ago in reply to Steve Clynes

TI__Expert 7225 points

Hi Steve,

I have shared the schematics with you over email already. Please check your emails with subject " HDMI issue in Netra..."

Thanks & Best Regards

Feroz

0 Steve Clynes over 13 years ago in reply to K Md Feroz Irfan

TI__Mastermind 43875 points

The first thing I see is that R35 should be 5K9 and not 698R.

This would actually cause the output to swing more, not less though, so I am not convinced this is the root cause.

Can you please replace this resistor and check multiple boards to see if this is a board specific issue or if it affects all boards?

BR,

Steve

0 sweta bhatt over 13 years ago in reply to Steve Clynes

Expert 2345 points

Hi,

This was a design issue. Connections for HDMI connector were not as per HDMI specification.

After fixing connections properly, this is working fine.

Thanks,
Sweta

0 Steve Clynes over 13 years ago in reply to sweta bhatt

TI__Mastermind 43875 points

Sweta,

Please also make sure that you do the R35 change.

BR,

Steve

0 sweta bhatt over 13 years ago in reply to Steve Clynes

Expert 2345 points

Hi Steve,

Thanks for update. Yes, we also did R35 change. This also contributed to make it work.

Regards,
Sweta

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HDMI issue in DM8168 design