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DS90UH948-Q1EVM: DS90UH948 Pattern Generator Output Problem

Mustafa Tarhan
Intellectual 1300 points
Part Number: DS90UH948-Q1EVM
Other Parts Discussed in Thread: ALP

************************

 Hi 

Our customer connect their own test card to the Deserializer EVB, which includes the ds90uh949 IC,

When the SER-DES lock is done with the UCD-323 pattern generator, we can get the LVDS output from the DES and read it in the internal EDID located in the IC. CASE-1

However, when we try it with HDMI, the PC does not see second screen, so we cannot get LVDS output, CASE-2

I share the data below via the ALP GUI of both halves, we are waiting for your return.

 

UCD-323: Pattern Generator used;  CASE-1

 

 

PC HDMI Port used: CASE-2

 

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  • 0
    TI__Intellectual 2810 points

    Hello Mustafa,

    Thank you for reaching out. I will look into it and get back to you within 1-2 days.

    Thanks,
    Kate

  • 0 in reply to Kate Hawkins
    TI__Intellectual 1300 points

    Hi Kate

    thanks a lot for the support.

    Based on our phone call with customer, we saw that the problem was caused by the HPD pin, the PC does not detect HDMI because it is always low when the HPD pin is connected to the IC,

    However, when they separate the HPD pin from the IC, we see it as PC HDMI and they see that they lock with DES and then they access LVDS data,

    Why is the HPD pin LOW when they connect it to the IC, we look forward to your comments 

  • 0 in reply to Kate Hawkins
    TI__Intellectual 1300 points

    Hi Kate

    thanks a lot for the support.

    Based on our phone call with customer, we saw that the problem was caused by the HPD pin, the PC does not detect HDMI because it is always low when the HPD pin is connected to the IC,

    However, when they separate the HPD pin from the IC, we see it as PC HDMI and they see that they lock with DES and then they access LVDS data,

    Why is the HPD pin LOW when they connect it to the IC, we look forward to your comments 

  • 0 in reply to Mustafa Tarhan
    TI__Intellectual 2810 points

    Hello Mustafa,

    The 949 IC holds HPD low until it is ready to receive signals from the source, at which point it will release HPD to be pulled up to 5V (RX_5V) with a 1kOhm resistor. Do you have this pull up resistor included?

    The 948 initiates the connection by first providing the 5V (2.4V-5.3V) power signal to the HDMI interface. This will let the 949 know that it is ready to communicate. Is this being done?

    How are you reading the value of the HPD?

    Thanks,

    Kate