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SN65LVDS93B-Q1: pixel bit ordering

Marvn Arcangel
Genius 14970 points

Part Number: SN65LVDS93B-Q1

Hi Team,

I am planning to use the SN65LVDS93B-Q1 to convert the RGB signals from my host processor to LVDS for my display.  My host processor has native RGB565 display signals (16-bit).  My initial thought was to use the display example in Figure 14 on page 19 of the SN65LVDS93B-Q1 datasheet, which shows an 18-bit configuration, and then just ground the inputs for the two bits (Red and Blue) that are not used in the RGB565 configuration.

I was originally thinking that I should ground the two LSBs on the SN65LVDS93B-Q1:  D0 for Red and D15 for Blue.  Then I realized that the difference between the 24-bit example and the 18-bit example has the MSBs grounded and not the LSBs, so I thought I should ask here first to clarify.

For using the SN65LVDS93B-Q1 in RGB565 (16-bit) configuration, should I ground D0 for Red (treating D6 as MSB and D1 as LSB), or ground D6 (treating D4 as MSB and D0 as LSB)? 

Likewise for Blue, should I ground D15 (treating D22 as MSB and D18 as LSB), or ground D22 (treating D21 as MSB and D15 as LSB)?

Regards,

Marvin

  • 0
    TI__Mastermind 26540 points

    Hi Marvin,

    The "8.3.2 LVDS Output Data" shows how the RGB bits or data bits D0-D27 will be serialized on the LVDS output. There are 3 different formats shown in the table. You will find that compared to 8-bit FORMAT-1 vs 6-bit, the MSBs are grounded in the 6 bit version. So this will depend on which format the RGB input pins are connected from the host to the LVDS93B.

    From the host controller, you should check which output format is used, and make sure that the output also matches the display. Which format data is the display expecting? These formats are also often referred to as JEIDA or VESA formats (shown in section 3 here: https://www.ti.com/lit/an/snla014a/snla014a.pdf).

    To summarize, you will just need to make sure the formats are set up so that each RGB bit from the input matches what the display is configured for. Whether to ground LSB or MSB depends on the input format).

    Best regards,
    Ikram