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Original question:

DS90CF383 LVDS color bit mapping 24 bit LDI to 24 bit VESA

DS90CR286A: LVDS to HDMI

William Caruana
Prodigy 70 points
Part Number: DS90CR286A
Other Parts Discussed in Thread: DS90CR286, AM4378, DS90CF383, TFP410, DS90CF386

I am trying to take the LVDS output of DS90CF383BM chip and turn it into HDMI output by using the DS90CR286ATD and TFP410PAP chips. My question is the bit order coming out of the DS90CR286 chip the same as it was going into the DS90CF383BM chip once it is researlized? The data going into the DS90CF383BM is from the AM4378. Also are tese the right chips to use for LVDS to HDMI transformation?

  • 0
    TI__Guru** 103215 points

    Hello William,

    I would suggest using DS90CF383 -> DS90CF386 -> TFP410 

    We have an example board to do this function which you can reference here for your design:

    FPD23DAEVM_User_Guide.pdf

    The LVDS to parallel RGB bit mappings are the same between DS90CF383 and DS90CF386 so there should be no issue with the bit mappings

    Best Regards,

    Casey 

  • 0
    Prodigy 70 points

    The original DSS_DATA (AM4378) to LVDS (DS90CF383) used the following data connection:

    DSS_DATA output                                    DS90CF383 data input

    0                                                                 15

    1                                                                 18

    2                                                                 19

    3                                                                 20

    4                                                                 21

    5                                                                 22

    6                                                                 16

    7                                                                 17   

    8                                                                 7

    9                                                                 8

    10                                                               9 

    11                                                               12

    12                                                               13

    13                                                                14

    14                                                                10

    15                                                                11

    16                                                                0

    17                                                               1

    18                                                               2

    19                                                               3

    20                                                               4

    21                                                               6

    22                                                               27

    23                                                               5

    24                                                               24

    25                                                               25

    26                                                               26

    27                                                               23

    My question is this, should I hook up the DS90CF386  to TFP410 with this bit mapping or use the one on the TI reference design?                                                        

  • 0 in reply to William Caruana
    TI__Guru** 103215 points

    Hello William,

    Where did the above pin mapping come from? Do you have some info on the DSS_DATA pin to RGB/Sync signal mapping?

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Prodigy 70 points

    From the TI document "How to bridge HDMI/DVI to LVDS/OLDI (slla325c), Table 3, I inherited it from previous engineers design taking DSS_DATA to LVDS out.

  • 0 in reply to William Caruana
    TI__Guru** 103215 points

    Hello William,

    Table 3 in the app note is assuming VESA color mapping, where MSBs are on the Y3 line so the R/G/B bits to CF383 input pins align with what is shown in the table. The reference design attached is assuming JEIDA is the LVDS format used. So first please confirm that the output format of DSS_DATA is VESA.

    If so, then you should use that same table as a reference for the pin number to color mappings when connecting to TFP410 as it will be different than the reference design. You can see the table in section 7.3.1 of the TFP410 datasheet for the R/G/B bits to input pins and also in the schematics of the reference design on page 15 you can see the pins labeled with the corresponding colors.

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Prodigy 70 points

    Thanks for the help Casey, I really appreciate it!