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DS90UB948-Q1: DS90UB948Q1 dev kit not linking video with deserializer

bryan bickel
Prodigy 10 points
Part Number: DS90UB948-Q1
Other Parts Discussed in Thread: DS90UH949-Q1EVM

Tool/software:

I'm having trouble troubleshooting a derserializer that wont link video with the serializer. However, a known good deserializer also wont link video and now I'm confused as to why they won't link.

W/O the video link I can't continue to troubleshoot. It does not look like there are any CRC errors which leads me to more confusion.

My test setup includes the DS90UH949-Q1EVM w/ USB to a PC running analog launchpad and the 12 volt supply; and FPD link link cable between the Eval board and my test board w/ a deserializer, also powered. Super simple, shouldnt have any issues ---- and we've ran the same setup in the past.

Currently the error occurs independently of whether there's a display attached.

  • 0
    TI__Intellectual 2745 points

    Hi Bryan,

    I can help you troubleshoot this, but I have some questions to get started:

    1) Just to confirm, your setup is using a UH949 going into a UB948?

    2) Is this in single port or dual port mode? What type of cable is being used?

    3) What video timings are you programming?

    4) Can I see the script you are using to program the devices?

    5) What is the value of register 0x0C when the 949 is connected to the deserializer giving you issues? This register is a port specific register, so depending on what port setup you are using you will need to change register 0x1E to read back either port 0 0x0C, port 1 0x0C, or read back both separately.

    6) How are you determining that there are CRC errors?

    Best,

    Cameron

  • 0 in reply to Cameron Hoholik-Carlson
    Prodigy 10 points

    1) Just to confirm, your setup is using a UH949 going into a UB948?

    correct

    2) Is this in single port or dual port mode? What type of cable is being used?

    should be single port, using the fpd link quadrax cabling

    3) What video timings are you programming?

    default - -- 720p 

    4) Can I see the script you are using to program the devices?

    I dont recall needing one with analog launchpad previously when we've had video come up, so I dont have one ready actually

    5) What is the value of register 0x0C when the 949 is connected to the deserializer giving you issues? This register is a port specific register, so depending on what port setup you are using you will need to change register 0x1E to read back either port 0 0x0C, port 1 0x0C, or read back both separately.

    bit 1 and bit 0 are set, which are DES error and Link detect. So it makes sense link detect is 1 but i dont get why the deserializer error is occuring

    6) How are you determining that there are CRC errors?

    0x0A bit 1 is set

  • 0 in reply to bryan bickel
    TI__Intellectual 2745 points

    Hi Bryan,

    If bit 0 is set in register 0xC, then you are able to get link. In order to diagnose why there are DES CRC errors, I have a few further questions. 

    1) 

    bryan bickel said:
    should be single port, using the fpd link quadrax cabling

    Sorry, I should have been more specific. I meant is it a STP cable or a Coax cable?

    2) I see you mentioned the 949 is an EVM, is the 948 also and EVM or a custom board? 

    3) What mode straps are each device set to?

    4) When you are not getting video, is there active video coming into the serializer? In order to automatically bring video up, the SER needs to be able to detect the HDMI clock.

    5) If you clear the CRC errors by setting register 0x4 bit 5 to 1 followed by immediately setting it back to 0, do the CRC errors stop or do more appear in register 0xA and 0xB?

    6) Additionally, could you also probe the lock pin on the 948 to see if you have lock?

    Best,

    Cameron