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DS90UB948-Q1EVM: 1-Lane Coax mode - configuration issue, Lock LED blinking

stephane chami
Prodigy 50 points
Part Number: DS90UB948-Q1EVM

Dear Support team,

we are facing a poblem while trying to display a video on a LCD screen, using the Serdes products.

The configuration is as follow:

- Deserializer DS90UB948 (EVM)

- Serializer DS90UB949 (EVM)

- 1-Lane mode, using 1 coax cable

- video source: HDMI output from a PC

- Display: LCD Screen 1280x800 RGB 60fps

We attach pictures to illustrate HW configuration and parameters (DIP Switches for Mode SEL0/1)

The registers are forced to Coax mode and Single Link but it seems that there is a conflict. The register keeps changing from single to dual link mode automatically. (Unfortunately,  we can't find how to upload .txt files which should be useful to upload the local and remote registers....)

The image is not "fixed", Lock LED keeps blilnking. We face the same behaviour with the pattern generated by the EVM.

EDID configuration generated from these parameters:

pixel_clock  : 71.1
h_resolution : 1280
v_resolution : 800
h_blanking   : 160
v_blanking   : 23
h_back_porch : 80
v_back_porch : 10
h_sync_width : 32
v_sync_width : 3
h_size       : 21
v_size       : 13
d_gamma      : 2.2

Have we missed anything ?

Thanks for your precious help.

Best Regards,

  • 0
    TI__Mastermind 30515 points
    Hi Chami
    1. firstly you should check the lock status of ub948 and the HDMI i/f status of ub947.
    2.for the single coax applocation, pls check the cable parameter and the coax connector design in evm.
    3.pls also check whether edid is updated with your resolution.



    best rgds
    steven
  • 0 in reply to Steven(Shenzhen) Shi
    Prodigy 50 points

    Hi Steve,

    Thanks for your quick reply.

    1. What do you mean by checking the HDMI i/f status of ub947 ?

    2. Already done.

    3. EDID is updated with the right resolution ; the image is displayed correctly when using the DOUT0+ and DOUT- signals to transmit data (2-coax). It fails when we remove the coax cable connected on DOUT- (replaced by a 50 Ohms end resistance, as shown on the images sent)

    Any other suggestions ?

  • 0 in reply to stephane chami
    TI__Mastermind 30515 points
    1. it is the UB949's HDMI I/f status and UB948's FPD-Link input status. from the item3 above, it sounds the total link already can work.
    3. the issue seems to be: the image is displayed correctly when using the DOUT0+ and DOUT- signals to transmit data (2-coax). It fails when we remove the coax cable connected on DOUT- (replaced by a 50 Ohms end resistance, as shown on the images sent).
    from above description, the image has one black stripe, correct? please check UB948's lock status, and CRC bit error detection. thanks.

    best regards,
    Steven
  • 0 in reply to stephane chami
    Prodigy 50 points
    Is it possible to get the HW configuration for the duo EVM DS90UB948/9 using 1-Lane transmission on one 1 coax ?

    In addition, why the registers are overwritten despite the fact that they should be set to a fixed configuration ?

    Any additional information concerning these evaluation boards is appreciated. We've followed multiple videos and application notes and it seems that we still miss something.

    Thank you in advance.
  • 0 in reply to stephane chami
    TI__Mastermind 30515 points
    sure, you can. you can visit www.ti.com to get UB948 and UB949 EVM user guide which have sch. and layout for your reference.
    regarding the reg. overwritten issue, sorry I can't understand your question well, you can read which registers have this issue and check these "overwritten reg." names in d/s. for few registers of UB948, they can be updated from the serializer's setting, such as ID address etc.

    best regards,
    Steven
  • 0 in reply to Steven(Shenzhen) Shi
    Prodigy 50 points

    Hi Steve,

    we finally got our set up functional.

    There is a curious behaviour we would like to understand:

    - on the Deserializer x948, we found out that the register 0x39 should be set at 0x02. When set with this value, we get our set-up working properly. But we are unable to explain why. Any idea ? Is it the right configuration ?  This registers is flagged as reserved...

    Thanks,