TUSB1046EVM: INT053 Rev. F Display Output Not Working

Hi,

what is the status of R36/ R37? can you measure the common mode of the AUXp and AUXn signals?

Do you see the type-C monitor pop up on you display settings window? Should look something like this.

Thank you for the reply!

Both R36 and R37 are populated. The monitor pops up in the display settings window, but nothing is displayed on it.

There is about 2.07V between AUXp and AUXn.

Hi Phillip,

This value is lower than expected. Are you able to test with multiple DP sinks and see if this value changes?

I also notice that there is a Cypress module (I'm assuming this is the type-C to DP converter). Is there a way you can test without this module? I like to eliminate as many variables as possible while debugging.

Additionally from what I see in the schematic, we cannot have both R36 and R37 populated as they share a pad. Can you double confirm if both are populated?

Cypress module is a USBC analyzer, which has CC and SBU pins exposed. As the AUXp and AUXn are not easily accessible, we have measured the voltages across SBU1 and SBU2 of the connected Cypress module. 

Regarding R36 and 37, we have populated it as it was mentioned in a response to this forum post. 

I have also tested the setup without the Cypress module, observing similar behavior in both scenarios

Hi Phillip,

Understood. regarding the AUX common ode measurements, were you able to gather data with other sinks?

Additionally, I missed this earlier, but AUX common mode measurements are done with reference to ground. 

AUXp should be approx. 3.0V

AUXn should be close to 0.3V

If this is not the case, AUX may not be properly communicating.

An easy way to test this is if you are able to see the display information in advanced display settings:

Thank you, Vishesh.

The display properties are correctly communicated. I see the proper resolution and framerate, as well as the model number of the connected monitor.

I couldn't measure the AUXp and AUXn from different places, but by measuring SBU1 and SBU2 with GND, I am getting 2.75V and 0.28V.

Hi Phillip,

So now we know that the AUX and HPD is communicated properly. The only thing I can think of is performing a continuity test across the MUX to make sure 4 lane DP is enabled and the paths are connected. Are you able to try using I2C here?

Additionally try increasing the EQ. This may simply be a signal quality issue rather than a functional fail.