TPD12S521: HDMI display output not working

Cora Ferrer

Part Number: TPD12S521

Hi!

We have a very similar set up and problem as in this previous question:

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1114255/tpd12s520-hdmi-output-not-working/4130130?tisearch=e2e-sitesearch&keymatch=TPD12S521#4130130

In this case, we are already using TPD12S521 as source, but still no data is shown on the display. There is some information shown on the serial communication about the display (image attached), but way less information than if we would plug the same module in the manufacturer's eval PCB (there are more options about "Modes", for example).

Any insight how to solve this?

Is this related to the HDMI 1.4 version? The eval module where it works has a IC with HDMI 2.0 and backwards compatible standards.

We also modified the I2C // CLK_IN and DAT_IN pullup resistors, but there was no change in the issue here.

Thanks for any help!

Would be interesting to know how that case was resolved :D

Best,

Cora

over 2 years ago

0 Kuno Wu over 2 years ago

TI__Mastermind 18556 points

Hi Cora,

Re-assign to Shuai, who is in charge of EU, thank you.

Best Regards,

Kuno

0 Cora Ferrer over 2 years ago in reply to Kuno Wu

Prodigy 80 points

Hi!

We have been measuring voltages. We see something weird.

On the source side we don't see any voltage. On the Connector side when the HDMI cable is plugged in, we see 3.3V on the +lines TXDs.

Does this indicate something wrong on the configuration?

Best,

Cora

0 Shuai Yuan over 2 years ago in reply to Cora Ferrer

TI__Intellectual 2290 points

Hi Cora，

Thanks for your reaching out, I will look into this case and then come back to you.

Best regards

Shuai

0 Shuai Yuan over 2 years ago in reply to Cora Ferrer

TI__Intellectual 2290 points

Hi Cora,

Could you please help check the 5V_SUPPLY and LV_SUPPLY status first?

It's better to observe the voltage level for 5V_SUPPLY and LV_SUPPLY by oscilloscope. Because these are only two recommended operation conditions for power supply. I want to confirm if the device can work normally.

Best regards

Shuai

0 Cora Ferrer over 2 years ago in reply to Shuai Yuan

Prodigy 80 points

Hi!

It turned out to be a simpler issue and solution.

Reference design used an ESD IC (TPD12S521 alternative) that was internally connected on the transmission lines. When changing to this one, we didn't realize that there is no connection between [Source pins - IC - Connector pins] by the schematic symbol, so no errors were given on the layout rules check.

The issue was quickly found on the layout once we wanted to do some different testing on the TDX lines

We patched short-circuiting the transmission lines and it works :D

I'm attaching the image for reference, might be useful to someone! dummy error // easy fix!

Thanks!

Cora

0 Shuai Yuan over 2 years ago in reply to Cora Ferrer

TI__Intellectual 2290 points

Hi Cora,

Thanks so much for your kindly sharing.

I think it's also helpful for other people who will choose TPD12S521

Best regards

Shuai

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TPD12S521: HDMI display output not working