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Original question:

DS90UB948-Q1: How to detect external lvds signal in test pattern mode using internal clock？

DS90UB948-Q1: DS90UB948-Q1: DS90UB948 LVDS Output Single Abnorm

user6204151
Prodigy 40 points
Part Number: DS90UB948-Q1
Other Parts Discussed in Thread: ALP, USB2ANY

Hi Ti expert :

     We used the serializer is DS90UB941AS-Q1 and the deserializer is DS90UB948-Q1. The connection diagram  appears as follows:

Now in our processor can  visit  DS90UB948 I2C addr, but DS90UB948 LVDS output single is continuous high level，for example D0- is 1.5V D0+ is 1.0V.

 When I use ALP  to connect  DS90UB948, and set  Test Pattern Mode, DS90UB948 LVDS output single is still continuous high leve.Please help me .

Thanks!

  • 0
    TI__Expert 5480 points

    Hello, 

    Can you give me more details as to what you are trying to achieve? Are you trying to reduce the swing level? Are you not seeing data toggle high to low/ low to high? 

  • 0 in reply to Sally Cheung95
    Prodigy 40 points

    Hello,

    1.what you are trying to achieve?

    As the question i feedback before, I wan't  use DS90UB948 to output LVDS single to light up 1920x720 resolution LVDS screen. The main  circuit diagram as follows:

    2.trying to reduce the swing level?

    Do you mean reduce the swing level of oscilloscope ？

    3. data toggle high to low/ low to high? 

    I can't seeing  data toggle high to low/ low to high in all of  DS90UB948's LVDS single pins.

  • 0 in reply to Sally Cheung95
    Prodigy 40 points

    Hello ,

         In addtion , The debugging method I have done as follows:

    1.DS90UB941 link with DS90UB948 ,and DS90UB948 LOCK pin is high. Then i use usb2any to connect DS90UB948 i2c，and set DS90UB948  Test  Pattern Mode in ALP. In ALP pattren generator control select enable generator and color bars, video control timing source select external.

    2. Disconnect DS90UB941 use DS90UB948 alone.Use usb2any to connect DS90UB948 i2c，and set DS90UB948  Test  Pattern Mode in ALP. In ALP pattren generator control select enable generator and color bars, video control timing source select internal.

  • 0 in reply to user6204151
    TI__Expert 5480 points

    Hello, 

    Did test 1 or 2 have display output to the screen?

  • 0 in reply to Sally Cheung95
    Prodigy 40 points

    Hello, 

            Test 1 or 2 have no display output to the screen, and DS90UB948 lvds output single is continuous high level.

    we also measure  DS90UB948 lvds outpu single without display screen, but the  DS90UB948 lvds output single is continuous high level.