TMDS181: Handling for SCL_SRC and SDA_SRC

Sadanori Kato

Part Number: TMDS181

Hi,

The ports of SCL_SRC and SDA_SRC are connected to HDMI TX ports of DDC_SCL and DDC_SDA in the source side application, but are connected to GND in the sink side application.
Could you tell me why those ports are connected to GND in the sink side application ?

Best regards,
Kato

over 7 years ago

0 Francisco Javier Zamudio over 7 years ago

TI__Expert 5455 points

Hello Sadanori

In this case, we are considering a different kind of applications, then in one case, you will use the DDC option on HDMI. On the other hand, As
sources are not consistent in implementing all aspects of the DDC link, TI recommends configuring the TMDS181 as per Figure 35 in case of sink side applications.

Regards
Francisco

0 Sadanori Kato over 7 years ago in reply to Francisco Javier Zamudio

Guru 36540 points

Hi Francisco-san,

Thank you for your reply.

Should the ports of SCL_CTL and SDA_CTL be connected to the ports of DDC line in the source side application such as figure 32 ?

Best regards,
Kato

0 Francisco Javier Zamudio over 7 years ago in reply to Sadanori Kato

TI__Expert 5455 points

Hello Sadanori

Sorry but now I don't understand your question. CTL lines are for the I2C internal configuration. In figure 32 these lines are connected to the source because the source has the control of the TMDS181.

Regards
Francisco

0 Sadanori Kato over 7 years ago in reply to Francisco Javier Zamudio

Guru 36540 points

Hi Francisco-san,

Thank you for cofirming.

I understood.

Best regards,
Kato

0 Sadanori Kato over 7 years ago in reply to Sadanori Kato

Guru 36540 points

Hi Francisco-san,

Sorry for confusing you.
There was a typo in my question above.
So, could you please give me your advice whether the ports of SCL_SRC and SDA_SRC should be connected to the ports of DDC line in the source side application such as figure 32 ?

Best regards,
Kato

0 Francisco Javier Zamudio over 7 years ago in reply to Sadanori Kato

TI__Expert 5455 points

Hello Kato-san

It depends on the application if you will use these lines, you must to connect to the DDC lines in the source side and sink side like figure 32 (pull-ups with the correct value, in this case, 2k).

Regards
Francisco

0 Sadanori Kato over 7 years ago in reply to Francisco Javier Zamudio

Guru 36540 points

Hi Francisco-san,

Thank you for your reply.

I have an additional question.
For the sink side application, is it possible to connect the ports of SCL_SRC and SDA_SRC to GND, directly connect the ports of HDMI TX DDC_SCL and DDC_SDA to the ports of SCL_SNK and SDA_SNK such as the source side application ?

Best regards,
Kato

0 Francisco Javier Zamudio over 7 years ago in reply to Sadanori Kato

TI__Expert 5455 points

Hello Kato-san,

Yes, you can. But I recommend you to use the connection like sink side application.

Regards
Francisco

0 Sadanori Kato over 7 years ago in reply to Francisco Javier Zamudio

Guru 36540 points

Hi Francisco-san,

Thank you for your response.
I understood.

Best regards,
Kato

Interface

Interface forum

TMDS181: Handling for SCL_SRC and SDA_SRC