• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 32 subscribers
  • Views 601 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Convert PECL Video to VGA

Kevin Connor
Prodigy 10 points

I have an old piece of equipment that I'm trying to get up and running again. Most of the people who have worked on it are retired, so I'm a bit lost trying to trouble shoot. I'm pretty sure I have PECL video signals coming out of a graphics card and into a monitor which is no longer functioning (and was produced by a company which no longer exists), so the plan would be to take the existing video output and convert it into something that could go into a standard monitor, i.e. VGA or DVI. 

My video output is 16 pairs of video labeled video 0+/- to video 15 +/-. I also have an Hsync +/- and Vsync +/- pair, which I'm assuming is horizontal and verticle as well as a pair labeled DOTCLK+/- and a blank pair. There's a 25 MHz oscillator on the board as well, which could be the clock rate. 

Any ideas on how to convert this video? I'm really at a loss. 

Thank you for the help.

  • 0
    TI__Guru** 103215 points

    Hello Kevin,

    I'm not familiar with what you are describing for the video interface. Do you have any more information on what kind of video format/interface this is? 16 diff pairs doesn't sound like an OLDI style output and its unclear to me where the DE signal comes from since you mentioned you have HSYNC/VSYNC but not DE. If you want to convert to DVI you would at least need to figure out where all the sync information is coming from which includes HSYNC/VSYNC/DE, then we would also need to understand what your data pairs are. I.e. is this RGB666 data from 16 diff pairs? Which would correspond to R/G/B channels? Or is this a totally different type of video format. There's not much info to go by 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Prodigy 10 points

    Casey, 

    Thank you very much for the reply. I understand it's not much info to go on, and I wish I had more. I'm mainly staring at the circuit schematic, and looking at signal names. Can you spell out what DE stands for? I don't see any signal paths with that name, I can look for the full name. Converting to DVI would be just as good as an option as VGA, if that would be easier. 

    More info, the graphics card that is starting this signal is a TMS34020, which then sends signals through video pixel logic FPGA, PN: pLSI1032, which then goes through 3 video output registers, PN: 54ABT273, which then leaves the board. 

    There's also a dipswitch on the board that(I think) lets you switch between Mode 0, Mode 1 and Mode 2 (but there are also switches for HSync, VSync and SyncPol, so that might be why there are extra pins, for three different types of displays, but the switch is buried in the device, so it wouldn't be easy to use it on the fly. 

    I'm really shooting in the dark here and appreciate the help. Thank you very much. 

    -Kevin

  • 0 in reply to Kevin Connor
    TI__Guru** 103215 points

    Hello Kevin,

    DE is "Data Enable" which defines the boundary between active video information and video blanking in digital display formats:

    I wish I could help but the scope of this is pretty big and my best guess is that to convert from the video output interface you have to a modern display interface may require a more customized solution vs. something off the shelf. My best guess is that CBLNK from the TMS34020 is equivalent to the DE signal in modern non-interlaced LCD displays but not sure if that is output discretely in your board. Additionally even if you identify what signals you have, I'm not aware of a direct solution to translate that to VGA or DVI - I'd imagine that you probably need to have an FPGA to capture that data and pack it into a displayable 6-10 bit format anyways. I'm sorry but unfortunately I don't believe there is a simple solution we can suggest 

    Best Regards,

    Casey