HD3SS460: HD3SS460

Bruno Fazi

Part Number: HD3SS460
Other Parts Discussed in Thread: SN65DSI86, TEST2, TPS65982, TUSB1046-DCI

For our configuration, we have our iMX8XQP driving MIPI _DSI to the eDP chip (SN65DSI86). From that chip, the 4 video lanes (ML0-ML3) and AUX_P/AUX_N are directly DC connected to the HD3SS460IR (cross point mux). From the MUX, the CSBU1 and CSBU2 lines are directly connected to our USB-C connector. The CTX1/2 lines are capacitor coupled to the USB-C connector. We are having issues getting our USB-C display module to connect and present video.

Some other MUX chips show capacitive coupling on the input of the AUX(SBU) lines.

Is our configuration correct, or do we need cap coupling on the SBU inputs on the MUX ?

Thank you

over 2 years ago

0 David (ASIC) Liu over 2 years ago

TI__Guru**** 177676 points

Hi,

You would need to implement both AC coupling capacitor and pullup/pulldown as shown below.

For DSI86, please pull TEST2 pin to 1.8V thru a 1k to 10k resistor. Once TEST2 is high, the following steps must be performed:

1. Write 0x07 to register 0xFF. This will select Page 7.
2. Write 0x01 to register 0x16. This will make ASSR_CONTROL to be read/write.
3. Write 0x00 to register 0xFF. This will select Page 0.
4. Write 0 to bits 1:0 at register 0x5A. This will change from ASSR to Standard DP.

Do you have a PD controller in your design?

Thanks

David

0 Bruno Fazi over 2 years ago in reply to David (ASIC) Liu

Prodigy 30 points

Thanks David ! The 460 datasheet seemed to indicate a direct connection of the video source (GPU) page 18 of SLLSEM7D –JANUARY 2015–REVISED JANUARY 2017. To answer your question ... yes, we also have the TPS65982 in our design.

0 David (ASIC) Liu over 2 years ago in reply to Bruno Fazi

TI__Guru**** 177676 points

Hi,

Page 18 was focused more on the DP lane mapping over USB Type-C, it was not meant to be a detailed implementation.

Have you tried to enable the DSI86 color bar pattern generation? This will help isolate the issue between the DSI input or the DP output.

Thanks

David

0 Bruno Fazi over 2 years ago in reply to David (ASIC) Liu

Prodigy 30 points

Thanks David - we haven't tried using the color bar generator - good suggestion.

0 Bruno Fazi over 2 years ago

Prodigy 30 points

Hi David,

We are still facing issues with our configuration (see above). We realized that according to the eDP chip (SN65DSI86), it already contains the AC coupling caps within the package. We incorporated the pullup and pulldown resistors as suggested. We tried additional coupling capacitors too just to see if there was a difference but, no luck. The AUX_P and AUX_N lines going into the cross point mux (HD3SS460IR) have an amplitude of ~ 1V p-p centered about 0V as measured with a differential scope probe. When we use our TI evaluation boards ( SN65DSI86/SN65DSI96 EVM and TUSB1046-DCI), we are able to get video on our attached USB-C display. When scoping the output of the TUSB1046, we saw a differential voltage of ~ 2.5V. The datasheet (p8) for the TUSB listed different common-mode voltages for AUXp (0-0.4V) and AUXn (3.0-3.6V).

Any thoughts on what may be the issue ?

Thanks,

Bruno

0 David (ASIC) Liu over 2 years ago in reply to Bruno Fazi

TI__Guru**** 177676 points

Bruno

Can I take a look at your schematic?

Thanks

David

0 Bruno Fazi over 2 years ago in reply to David (ASIC) Liu

Prodigy 30 points

Hi David,

Can I send one to your e-mail address?

Thanks - Bruno

0 David (ASIC) Liu over 2 years ago in reply to Bruno Fazi

TI__Guru**** 177676 points

Bruno

Can you please accept my friendship request? You can then send me the schematic in a private message.

Thanks

David

0 Bruno Fazi over 2 years ago in reply to David (ASIC) Liu

Prodigy 30 points

David - i accepted the request.

Bruno

0 David (ASIC) Liu over 2 years ago in reply to Bruno Fazi

TI__Guru**** 177676 points

Bruno

I sent you a private message asking for schematic, would you please check?

Thanks

David

0 David (ASIC) Liu over 2 years ago in reply to David (ASIC) Liu

TI__Guru**** 177676 points

Bruno

I will close this thread for now. You can reply back to this thread if you need any additional support and the thread will re-open.

Thanks

David

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HD3SS460: HD3SS460