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THS8135 connction to DM8148

Bryan Busacco
Expert 1215 points
Other Parts Discussed in Thread: THS8135, THS8200, TPD7S019

THS8135 connction to DM8148.

 

We are looking for advice on setting up the video output system as a whole, supporting 10-bit video, seperate HSYNC/VSYNC in addition to embedded SYNC's.

1) In our application we want to support 10-bit video. Our first concern is that we were told the DM8148 does support this, but we don't see enough pins on the IC. Can you conform that we do in fact have 10-bit video on the DM8148?

2) We need to provide HSYNC and VSYNC to the DB-15 video connector. These come directly from the DM8148. Should we buffer these or do you suggest driving them out the connector directly from the DM8148? Buffering provides a layer of physical protection, better to blow up a buffer than the DM8148 if a short or something crazy happens!. What do you suggest?

3) We would like to support seperate HSYNC and VSYNC as I mention above, but also the option to embed the SYNC's. This will provide the most system flexability. I see that the THS8135 does support this, can you guide us in connecting this up? It looks like we'll take the HSYNC and VSYNC to the THS8135, but will we need external circuitry to turn them on and off when embedding, or not embedding them? Maybe supporting both modes is popular. Let us know how to hook all of this up.

Thank you,

 

Bryan Busacco 

  • 0
    TI__Mastermind 43875 points

    For VGA applications you will actually find very few monitors which will correctly accept VGA with sync on green, so depending on your application I would probably not worry too much about sync on green. If you truly need SOG then you might want to look at the THS8200.

    To be fully VGA compliant you should level shift the sync signals to 5V. Might I suggest using the TPD7S019 ESD protection and level shifter which also provides protection and level shifting for the DDC lines as well as a current limited 5V supply for the monitor EDID.

    [Edit, corrected VOut[1]]

    For 30 bit output you can use VOut[1]. Check section 3.2.23 of the datasheet for ball assignments.

    BR,

    Steve

  • 0 in reply to Steve Clynes
    TI__Genius 16810 points

    Is component video support also required?  The THS8135 has typically been used primarily for graphics supprt, since sync insertion for video required addtional logic to control sync insertion.  The THs8200 can support sync insertion directly from HSYNC and VYSNC inputs or from bt656 type embedded syncs.

    Addtionally, the THS8135 requires 1.8V I/O, while the THS8200 supports 3.3V I/O.

    Regards,

    Larry

     

     

  • 0 in reply to Larry Taylor
    TI__Guru 66466 points

    Thanks Steve and Larry,

    I"m assisting Bryan with this question and the customer has followed up with the folling comments:

    1)      I’m using only the VGA in 1280x1024 resolution.  I’m not using the component output at all. Does this part match the DaVinci data format (for OpenMax)?

    2)      It seems the input and output interface are straight forward.  Has this part been used in another design using DaVinci 8148?

    3)      Does this part have a default power configuration ?

    Regarding the last point, I see that Larry had recommended the schematics from the TVP5151EVM and the TVP7002EVM User Guides in another post. Is there any other documentation we can provide the customer to further assist them?

    http://focus.ti.com/docs/toolsw/folders/print/tvp5151evm.html

    http://focus.ti.com/docs/toolsw/folders/print/tvp7002evm.html

    Best Regards,

    Ryan

  • 0 in reply to Ryan Andrews
    Expert 1215 points

    I will add one additional question/comment:

    4) I see that the PSP for many DaVinci devices indicates that there is NOT support for the THS8200. Based on this, are we selecting the right device for the output?

     

    Thank you,

     

    Bryan Busacco.

     

  • 0 in reply to Bryan Busacco
    TI__Genius 16810 points

    Bryan,

    Most Davinci customers have used the THS8200 over of the THS8135 due to 3.3V I/O support and better componet video sync insertion support.  The THS8200 also offers supports digital embedded sync that are embedded in the RGB or video datastream. 

    In the past we have supplied configuration setups for various formats with most customers using these in their on software solution.  Recently I believe there has been sample code created for setting up the THS8200, but this has probably not found its way to the PSP.  

    Setting up the THS8200 for a particular graphics format involves using I2C to program a set of registers in the THS8200.  If a single format is all that is requried, this should be a fairly siimpe task.

    Regards,

    Larry