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DS90UB949A-Q1: Video Card Setting display at 1920 x 1200 resolution

Mark Philip Felipe
Genius 11270 points

Part Number: DS90UB949A-Q1
Other Parts Discussed in Thread: ALP

Hi Team,

I have a customer inquiry, that may need assistance from E2E.

Video settings and recommended graphics hardware for using the DS90UB949 with a display at 1920 x 1200 resolution

Thank you in advance

  • 0
    TI__Guru** 103215 points

    Hello Mark,

    I'm not sure exactly what you are looking for. If you are just looking for a simple video source to output the HDMI to the 949A, then you could use a regular laptop. It can plug directly into the EVM for the device and if you have a proper EDID communicated from your remote monitor then it will automatically detect the desired resolution and output video. 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    TI__Genius 11270 points

    Hi Casey,

    Thank you for responding back, I'll relay this information. Maybe they could give us more details.

    Thanks

  • 0 in reply to Mark Philip Felipe
    Intellectual 460 points

    Hi Mark,

    The video hardware is produced by our customer, so I don't have access to how it's handling the EDID data. However, I can describe the symptoms we're seeing. According to the Analog Launchpad software, the serializer board can't detect the deserializer at all. However, if we power on the serializer board first, then wait around 10 seconds before powering on the display module, we manage to get a video signal across. We still have to set up the proper resolution by going into the graphics menu of the PC and manually changing the resolution of the "monitor." Once we start seeing an image on the display, the Analog Launchpad software shows that it is now connected to a video source, but still not connected to a deserializer. When we reached out to our customer for answers, they said they were only able to get the link to work with one specific PC. All the other laptops and desktops they tried failed to display any image. Hence, the question about graphics settings and hardware capabilities.

  • 0 in reply to Joshua Dunn55
    TI__Guru** 103215 points

    Hello Joshua,

    Are you using the EVM for 949A or a custom board? To me it sound like the customer may be using a custom board and connecting ALP to that, but if there is another processor on the board also trying to access the I2C bus, then the contention may cause some strange issues in ALP like what is described. Can you verify the situation?

    Thanks,

    Casey 

  • 0 in reply to Casey McCrea
    Intellectual 460 points

    Hi Casey,

    On our side, we're using the EVM for the 949A, and the customer is using a custom board. They're also connecting to the I2C bus, but they should be operating in slave mode, not master mode. The customer part is a display module with touch screen, and the touch controller will be acting as an I2C slave.

    Thanks,

    Josh

  • 0 in reply to Joshua Dunn55
    TI__Guru** 103215 points

    Hello Joshua,

    So the 949A EVM is the one connected to ALP via USB and it is reporting that there is no DES connected? What configuration is being used? coax or STP?

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Intellectual 460 points

    Yes, that describes the setup perfectly.

    1. The computer is outputting HDMI to the EVM

    2. The EVM is connected to ALP on the computer over USB

    3. The EVM is connected to the customer part, which contains a 948 deserializer, through the STP connection

  • 0 in reply to Joshua Dunn55
    TI__Guru** 103215 points

    Hello Joshua,

    Does ALP indicate there is a remote deserializer missing only when video is going to the display? Or does it not show a deserializer under any condition?

    It sounds like there may be a back channel signal problem. Can you please send schematics for the customer module for review?

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Intellectual 460 points

    ALP will not show a deserializer connection under any circumstances, but it also won't show a video source connection until video is being sent to the display (over LVDS). However, if the display module is then powered down, ALP will still report the video source connection.

    Unfortunately, I don't have access to the customer schematics. Besides, while I appreciate your assistance and I welcome any advice you can give, trying to debug our customer's design is ranging a bit far afield for this question. If you're satisfied that an issue with the display module is what's causing this behavior, that's all I can really ask.

    That being said, is there anything more on the serializer end that might be causing the problem?

  • 0 in reply to Joshua Dunn55
    TI__Guru** 103215 points

    Hello Joshua,

    If you are using the 949A EVM for the serializer side then I don't think there is a problem there which is why I suspect some issue with the deserializer side, specifically with regards to the back channel communication over the FPD Link. This could cause some weird issues like the DES not showing up in ALP or intermittent video (because the 949A will not report to the HDMI source that it is ready for video until the DES reports that it is locked to the SER over the back channel). 

    One thing you could try just for test would be to force link detect and link active in the 949A and then see if this gives you more consistant video transmission in the forward direction. This means the SER won't care at all about what it is getting from the DES on the back channel. It will just indicate to the HDMI source that it is ready for video and start sending out the video it is receiving blindly:

    0x5C[6] = 1 and 0x5B[0] = 1

    This is not a long term solution but may help you determine if the source HDMI side is really the issue or if it is related to the DES connection. 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Intellectual 460 points

    Hi Casey,

    That's some very useful information. I probably won't get a chance to try it until Monday, but I will post an update then.

    Thanks,

    Josh

  • 0 in reply to Joshua Dunn55
    Intellectual 460 points

    Hi Casey,

    Sorry for the delay. Here's what I found:

    Setting 0x5C[6], 0x5B[0] and 0x5B[1] will cause an image to appear on the screen, so that we no longer have to go through the power-up sequence of first turning on the board, then waiting, then turning on the screen. We can turn them all on at the same time, and then use these bits to cause the image to appear.

    Based on this result, it's looking like the deserializer side is the issue, not the HDMI side. We're in talks with our customer.

    I have one additional question- what exactly is the difference between the FORCE_LINK and the FORCE_LINK_RDY bits?

  • 0 in reply to Joshua Dunn55
    TI__Guru** 103215 points

    Hello Joshua,

    FORCE_LINK (in conjunction with FORCE_DUAL) sets whether the link is single or dual mode based on the capabilities of the deserializer which are conveyed over the back channel. 

    FORCE_LINK_RDY bypasses the back channel detect to tell the serializer that the deserializer is ready to receive video regardless of the lane count configuration. 

    Best Regards,

    Casey