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SN65DSI83-Q1: Wrong I2C Values during screen blank

Adarsh Verma
Prodigy 80 points

Part Number: SN65DSI83-Q1

Tool/software:

Dear Expert,

We are using the SN65DSI83-Q1 as our MIPI-to-LVDS converter and are encountering a blanking issue. In certain instances, when the device is toggled ON, the screen goes blank with no display, despite the device functioning correctly as confirmed by a screencopy.

Additionally, we observed that during these blanking occurrences, the i2cdump of the SN65DSI83-Q1 shows incorrect values. Could you please assist in diagnosing the root cause of this issue? Specifically, is there a connection between the incorrect register dump values and the blank screen occurrences?

Regards,
Adarsh Verma


Working normal ON

I2Cdump when Working Normal ON

I2Cdump when Working Normal OFF

I2Cdump when Blank Occurs

  • 0
    TI__Guru**** 187851 points

    Hi,

    The LVDS output timing is generated based on the CSR values programmed in the corresponding video parameter fields. The following values need to be programmed to create the timing for the LVDS panel; HSync pulse width, HSync Back Porch duration, and VSync pulse width. So DSI83-Q1 registers must be correctly programmed for the display to work, otherwise you may have a blank screen. 

    Looking at the register dump, it looked DSI CLK is used as the clock source. If the DSI CLK is used as the clock source, are you putting the DSI CLK in HS mode only? Are you also following the initialization sequence as shown below?

    Do you also have multiple devices on the I2C bus? If this is the case, is it possible to isolate the DSI83-Q1 such that it is the only device on the I2C bus? Can you also monitor the I2C bus and make sure no I2C writing is happening when there is a blank screen?

    Thanks
    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 80 points

    Dear David,

    Yes, the DSI clock is operating in HS mode, and we are following the initialization sequence as outlined in the datasheet.

    Currently, we do not have the capability to isolate the device as the sole component on the I2C bus. Additionally, I should mention that the blanking issue occurs randomly, adding complexity to the debugging process thus it is difficult to monitor it

    Best Regards,
    Adarsh Verma

  • 0 in reply to Adarsh Verma
    TI__Guru**** 187851 points

    Adarsh

    DSI83-Q1 being an I2C secondary device, it should not change its I2C register value on its own. 

    Is it possible that you can probe and decode the I2C bus and make sure there is no writes to the DSI83-Q1 before the blanking screen occurs? Do you notice any events that can cause the blanking screen to occur?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 80 points

    Dear David,

    Will try this and let you know.