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SN65DSI85: SN65DSI85 LR function

Ryuuichi machida
Guru 12650 points
Part Number: SN65DSI85
Other Parts Discussed in Thread: DS90UB941AS-Q1

Hello,

Let me ask about usecase of LF function of DSI85.

For instance, when user input two kinds of images to each DSI channel as shown below.

In that case, I believe that same resolution image is NOT output from DSI85.

Because, this have only one PLL for LVDS.

This means only same image is output from LVDS even though DSI inputs are different.

So, could you please tell us which usecase do you assume for this function ?

Best Regards,

  • 0
    TI__Mastermind 35130 points
    Hi Ryuuichi-san,

    I believe the function of LR depends on the DSI source. The DSI85 can be configured for OE or LR but which one you would choose is decided by the output of your processor.

    If you want to output two different images with different resolutions then you should configure the device in the two single-channel DSI to two single-link LVDS operating mode. Please see table 4 in the datasheet for detailed explanations of each operating mode.

    Regards,
    I.K.
  • 0 in reply to Ikechukwu Anyiam
    Guru 12650 points

    Hello Anyiam-san,

    Thank you for your reply.

    If you want to output two different images with different resolutions then you should configure the device in the two single-channel DSI to two single-link LVDS operating mode. Please see table 4 in the datasheet for detailed explanations of each operating mode.

    I confirmed table 4. However I would like you to confirm about below sentence which you described.

    "If you want to output two different images with different resolutions"

    As I said previous thread, it seems that this device have only one PLL(implemented at ch A side) for LVDS outout.

    Therefore, I do NOT think that this device can NOT output different resolution from LVDS output.

    So, I asked usecase of LR mode. If I have mis-understanding, please correct me.

    Best Regards,

  • 0 in reply to Ryuuichi machida
    TI__Mastermind 35130 points
    Hi Ryuuichi-san,

    You make a good point about the PLL. Although there are two LVDS clocks they both will be the same frequency, so this certainly limits the resolution options. However, you can still have a different line length and frame rate for each channel as long as the clock frequency requirement for the panels are the same. This applies to the "two single-channel DSI to two single-link LVDS" operating mode.

    For LR mode, there's not really a special use case for this mode. The receiver will accept either OE or LR inputs, and it depends on the DSI source output and the engineer's preference.

    Regards,
    I.K.
  • 0 in reply to Ryuuichi machida
    TI__Mastermind 35130 points
    Hi again Ryuuichi-san,

    If you are interested in a DSI to LVDS device with two independent streams with independent resolutions, you can also take a look at the DS90UB941AS-Q1.

    Regards,
    I.K.
  • 0 in reply to Ikechukwu Anyiam
    Guru 12650 points
    Hello Anyiam-san,

    Understood.

    BR,