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Can DM6467T Drive this OLED RGB display through THS8200?

Helmut Forren
Mastermind 6805 points
Other Parts Discussed in Thread: THS8200

I'm working on my second generation DM6467T project.  I need to drive an OLED that has analog RGB inputs, specified as compatible with the VESA VSIS standard, which I believe to be DVI-A (DVI analog).  Simultaneously, I need to provide an NTSC output.  Unless I find a magic chip that can do both (suggestions?), I need to drive TWO SD channels out.  One can drive my existing ADV7171 for my NTSC output.  The other can drive a chip to drive the OLED display.

After searching everywhere but my own back yard, I discovered the THS8200, which is in fact on the same DM6467T EVM from which I derived my first generation project.  Of course, I replaced that HD chip with an ADV7171 because I was doing SD, but the EVM gives me a model for integrating the THS8200 back in.

While used in HD mode for the DM6467T EVM, I find that the THS8200 can accept BT.656 coming in.  Therefore, I ought to be able to make it coexist with my ADV7171.

The THS8200 can also generate analog RGB out, and I see horiz and vert sync outputs on a block diagram.  I'm hoping this will be or can be made compatible with the OLED at http://www.emagin.com/wp-content/uploads/2010/08/SVGA_Rev3_XL_User_Manual_Datasheet_Rev_4.pdf

Again, the OLED says this is VESA VSIS standard.  So, bottom line, can the THS8200 take BT.656 in and produce VESA VSIS standard out?

Any advice?

Thanks very much,

Helmut

  • 0
    Mastermind 6805 points

    I see that the THS8200 is capable of accepting 8-bit BT.656 coming in.  This is pretty explicit in the datasheet.  Please correct me if I'm wrong.

    I believe the THS8200 can produce three RGB analog outputs, as well as horizontal and vertical sync out.  Can this be made VESA VSIS compliant?

    So, can I configure the THS8200 to take BT.656 in and drive out VESA VSIS standard compliant?

    I want to connect this to the second of two operating DM6467T SD output channels (an ADV7171 on the first operating output channel), and drive the OLED at http://www.emagin.com/wp-content/uploads/2010/08/SVGA_Rev3_XL_User_Manual_Datasheet_Rev_4.pdf

    Thanks very much,

    Helmut

  • 0
    TI__Genius 16810 points

    Helmut,

    Yes the THS8200 supports 8-bit BT.656, however this standard is typically used for interlaced SD formats.  The THS8200 can support other formats via the 8-bit interface, but it cannot de-interlace.  The frame/line/pixel rate for the desired format needs to be correct at the THS8200 input.  The THS8200 can convert an 8-bit YCbCr interface to VESA RGB with separate syncs, provided the bt656 is progressive scan and is formatted correctly for the VESA format. 

    Will your BT656 be 4:2:2 YCbCr but formatted for a particular VESA standard?

    What formats do you need to support?

    What is the maximum pixel rate required?

  • 0
    Mastermind 6805 points

    Larry,

    Thanks very much for your help.  While I've gotten my first generation hardware running NTSC->DaVinci->NTSC, I'm barely keeping track of you here.  I am uncertain of EXACTLY what your questions mean...

    Interlace vs progressive:

    Note that DM6467T can support two SD output channels, channel 2 and channel 3.  I already have an ADV7171 on channel 2.  This outputs regular NTSC SD, which is interlaced.  I do not know if the data coming from the DaVinci and going into the ADV7171 is interlaced or not!  My code is based on the encodedecode demo, which was HD.  I changed things to make it SD, but in my code I still only ever see whole frames.  It goes through dmai library functions to go out.  So, I don't know where the change from full frames to interlacing occurs:  in dmai, code below that, in the DaVinci hardware, or the ADV7171 !!!!  

    I want to add the THS8200 to channel 3.  Doing so in a natural way, cloning code that I have already, I should be sending BT.656 formatted data to the THS8200.  This will be 8-bit YCbCr coming out of my YUV422SP buffer.  Again, I don't know if the THS8200 will receive progressive or interlaced data.  Perhaps you can tell me!

    I hear you about the THS8200 producing VESA RGB w/sync, "provide the bt656 is progressive scan and is formatted correctly".  This will be my CORE UPCOMING QUESTION.

    VESA format:

    I know nothing about VESA formats.  All I know is the OLED display to which I referred says it is VESA VSIS compatible.  So far as my data being "formatted for a particular VESA standard", can you please clarify?  Are you talking about row count and column count?  This also implies progressive or interlaced.  Are you talking about  4:2:2 YCbCr data sequencing (which is integral to bt.656 I think?)  I'm just not up to speed enough here!

    Pixel rate:

    The OLED display says it can handle a clock rate up to 56MHz.  It has a PLL to recover the clock; I assume this is from the RGB data w/o embedded clock.

  • 0 in reply to Helmut Forren
    Mastermind 6805 points

    any comments on the above?

  • 0 in reply to Helmut Forren
    Mastermind 6805 points

    Larry,

    If you're still available, I would greatly appreciate your continued input.  Can you look at my questions above and give me some suggestions?

    Thanks very much,

    Helmut

    Any other takers?...

  • 0 in reply to Larry Taylor
    Mastermind 6805 points

    Larry (or others):

    I've been studying further.  I just came across the fact that the THS8200 can interpolate from 4:2:2 to 4:4:4.  My understanding that this IS a form of de-interlacing.  If this is true, then the THS8200 actually CAN de-interlace an interlaced BT.656 stream coming from the DaVinci, for the purpose of sending it to the OLED.  

    This would leave only the pixel rate to consider.

    Thoughts?  Comments?

    ...

    Reading further, THS8200 datasheet section 3.1 says, "Supported input formats include 10/8 bit ITU-R.BT656 with embedded sync codes".  That suggests I can connect the THS8200 to simply DaVinci ch3 SD output, leaving ch2 SD output for something else I need.  The datasheet then says, "The use can optionally include a 4:2:2 to 4:4:4 interpolation on the color data path."  This implies it can de-interlace for me and then produce the RGB output.

    However, table 4-1 for "Supported Input Formats" does not mention BT656, so there's a bit of conflict between section 3.1 and table 4-1.

    -Helmut