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SN65DSI83TPAPRQ1: Issues with backlit display when device wakes up

Paula Gavuglio
Prodigy 10 points

Other Parts Discussed in Thread: SN65DSI83

Hello, 

We currently are using SN65DSI83TPAPRQ1 (Automotive single-channel MIPI® DSI to single-link LVDS bridge 64-HTQFP -40 to 105) part for our LVDS IC on a smart tablet device that is connected to a 10" touch screen LCD. 

We see a normal display/operation at most times, but as we are moving into stress testing - we have noticed a prominent issue with the device having a backlit screen when it wakes up from deep sleep (LCD completely asleep). 

We originally reached out to our smart module (SC20) manufacturer, Quectel to provide advise and revisit our design to confirm proper set up, and they advised we reach out to you as "the parameters required by convert_init_setup[] are provided by TI, and may need TI’s assistance in more attempts to achieve the best display effect."

Could you please point our team in the right direction/assign us a technical support member to further discuss the issues we are having to try to resolve this.

Best, 

Paula Gavuglio

SyncWise, LLC

  • 0
    TI__Guru**** 183901 points

    Paula

    For deep sleep, are you putting the DSI83 in the ULPS? How do you enter and exit the deep sleep mode?

    Thanks

    David 

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points

    Hello David, 

    Thank you for your response. I will have to rely on our engineering team to answer questions you posted above. I'll be sure they post feedback. 

    On a side note, please be advised I opened an internal CASE#CS0773908, with the request that an expert review our schematics which are strictly CONFIDENTIAL and cannot be shared publicly on this forum. If you can gain access to the CASE please review. Additional details and questions our team has on our end are provided below. 

    Description:

    • The issue looks like image disappears and becomes backlit screen, which usually occurs during device wake up or boot up (at different stages of a boot and kernel). Here is a video. The device is non-responsive to any captouch, and when reviewing system logs, it appears as if everything is working as expected and the cap-touch buttons appear to be responsive.
    • When reviewing the logs of this occurrence,  we get an error from SN65DSI83: CHA_UNC_ECC_ERR (DSI channel A packet processor detects an uncorrectable ECC error). However, when this error occurs, the LVDS pins of the SN65DSI83 are set to high level.
    • Please note our device is based off of SC20 module, which supports 4-lane MIPI_DSI, up to 1.5 Gbps/lane, HD (720P) @ 60 fps
    • Our team looked through other questions, and saw similar behavior reported in forum post. Please review..

    Please note, our team is working in parallel with Quectel (the smart module manufacturer) as well as our LCD manufacturer as there are so many connected pieces.

    In the meantime, please review and if you could advise on the following questions and provide feedback, we would greatly appreciate it.

    Questions:

    • Please advise the parameters required by convert_init_setup[]
    • Please advise the internal timing patterns - if you could provide over specs/tools - we would appreciate it. 
    • Please advise why we are receiving the ECC error. Is it expected to see the pins of the SN65DSI83 set to high level when this issue occurs?
    • Please advise what other steps we should check

     Thank you,  

    Paula

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points

    Hello David,

    In suspend function we do PLL disable after unpower IC

    In resume function, we enable power, fill in the IC configuration registers, then we do a soft reset (after 10msec)

  • 0
    Prodigy 10 points

    Hello David,

    I wanted to follow up about this case and ask when our team can expect to receive feedback to the questions I posted last week?
    Looking forward to your response.
  • 0 in reply to Paula Gavuglio
    TI__Guru**** 183901 points

    Paula

    How do you control the EN pin, do you have an external 0.22uF pulldown capacitor on it? Please check and make sure you are following the DSI83 initialization sequence as shown below.

    Thanks
    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points

    Hi David, 

    Thank you for the following up, however our team would like to continue this investigation in private within the Case I posted # CS0773908. 

    Looking forward to discussing this further in private your team within the Case.

    Best, 

    Paula

  • 0 in reply to Paula Gavuglio
    TI__Guru**** 183901 points

    Paula

    Would you please accept my request for friendship?

    Thanks
    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points

    David, I accepted your request and reached out via a private message. Let's carry on discussion there.

  • 0 in reply to Paula Gavuglio
    TI__Guru**** 183901 points

    Paula,

    Ok, let's move to the private discussion.

    Thanks

    David