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TPS65988EVM: PC doesn't recognize Display

Eriks Austrums
Intellectual 675 points

Part Number: TPS65988EVM

Hello,

We have TPS65988EVM and following the guide we connected PC with displayport cable to EVM and using USB-C to DP cable to a monitor , but nothing happens.
Looking at the leds on EVM I can see that the alternate DP mode is active but the HPD led is not on.
Using Application customization tool 6.1.1 i took this picture.

It looks like TPS65988EVM is not set up for alt mode DisplayPort? I'm working right out of the box , should I reprogram It with TPS65988EVM FW?

Best regards,

Eriks

  • 0
    TI__Genius 9630 points

    Hi Eriks,

    Please go into debug mode to see the current settings on the EVM. You may need to change some settings to successfully go into DisplayPort. Please check out the TPS6598x DisplayPort Alternate Mode app note for more information. 

    Thanks,

    Emma

  • 0 in reply to Emma Hoying
    Intellectual 675 points

    Hello,

    I checked the app note and as I see, everything is set up right. I confirmed it using PD analyzer, PD is negotiated , DP mode is entered and HPD high message is sent.

    I checked at the TPS65988EVM side and i can see that the HPD is not asserted , that explains why PC doesn't recognize the Display , But why is this happening? Why TPS65988EVM isn't asserting the HPD even if I can see it at display side , that It's asserted?

    https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/138/tps65988evm_5F00_to_5F00_display.7z

    I also checked the schematic for TPS65988EVM and I cant find the pull-down resistors on SBU pins for USB-C connectors. Is there a reason why they aren't used? Could this affect AUX channel as it uses the SBU pins ?

    Regards,

    Eriks

  • 0 in reply to Eriks Austrums
    TI__Genius 9630 points

    Hi Eriks,

    can you please describe your test setup? How are you connecting to the TPS65988EVM?

    Thanks,

    Emma

  • 0 in reply to Emma Hoying
    Intellectual 675 points

    Hello ,

    I followed the user guide

    The 7.1.3 Testing DisplayPort™ Alternate Mode section . My setup was , that I connected the power to the EVM, then the EVM to my PC with DP cable and from EVM port A to Display with USB type-c to DP cable. Leds that inticate that the Alternative mode is entered ligth up. But the PC doesn't see the Display.

    Regards,

    Eriks

  • 0 in reply to Eriks Austrums
    TI__Genius 9630 points

    Hi Eriks,

    I have ordered a cable and am awaiting its arrival to test your setup. Please allow me a few days for testing.

    Thanks,

    Emma

  • 0 in reply to Emma Hoying
    TI__Genius 9630 points

    Hi Eriks, 

    I tested part of this set up today and was able to get the results I was looking for for successfully DisplayPort. I could not get my computer to be a DisplayPort host with a HDMI to DisplayPort cable, so I am going to order another DisplayPort to Type-C cable to try this out. I should be able to test again in a few days when it arrives.

    Thanks for your patience,

    Emma