Simulate a VGA monitor connected to a computer?

Discussion in 'Video Hardware' started by notme, Jul 16, 2009.

  1. notme

    notme Guest

    Apparently different video drivers are loaded depending on if a monitor is
    connected or not. This is the case when connecting via VNC to a "headless"
    Mac Mini.

    Using just a Mini-DVI-to-VGA adapter won't load another driver.

    Is there a way to emulate a monitor connection?

    Is this a case of I^2C communication? Any simpler method?

    Thanks.
    N.
     
    notme, Jul 16, 2009
    #1
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  2. notme

    Tim Williams Guest

    "notme" <> wrote in message
    news:-september.org...
    > Is this a case of I^2C communication? Any simpler method?


    I think so. I can't get VGA from my laptop without I2C... when I try
    forcing it, Windows drops the data line (request, I suppose) for about 1ms,
    then it fails, not detecting anything. And I so wanted to get raw RGB+sync
    signals at the time... guess I won't be doing that, at least without
    something I2C on the line (EEPROM? uC?).

    Tim

    --
    Deep Friar: a very philosophical monk.
    Website: http://webpages.charter.net/dawill/tmoranwms
     
    Tim Williams, Jul 16, 2009
    #2
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  3. notme

    IanM Guest

    Tim Williams wrote:
    > "notme" <> wrote in message
    > news:-september.org...
    >> Is this a case of I^2C communication? Any simpler method?

    >
    > I think so. I can't get VGA from my laptop without I2C... when I try
    > forcing it, Windows drops the data line (request, I suppose) for about 1ms,
    > then it fails, not detecting anything. And I so wanted to get raw RGB+sync
    > signals at the time... guess I won't be doing that, at least without
    > something I2C on the line (EEPROM? uC?).
    >
    > Tim
    >

    Its a *long* time since I was digging around inside monitors but IIRC to
    fake one you'll need a 24C02 I2C EEPROM programmed with suitable VESA
    EDID data *AND* 75 ohm resistors to ground on the R B and G lines.
    Probably easiest to rob a dead CRT monitor for the EEPROM if this is a
    one off project. Otherwise you'll need to research VESA DDC2B and EDID.

    --
    Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
    ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
    [at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL:
     
    IanM, Jul 16, 2009
    #3
  4. notme

    JF Mezei Guest

    notme wrote:
    > Apparently different video drivers are loaded depending on if a monitor is
    > connected or not. This is the case when connecting via VNC to a "headless"
    > Mac Mini.
    >
    > Using just a Mini-DVI-to-VGA adapter won't load another driver.


    Not quite the same, but if you plug a VGA monitor to a MiniDisplayPort
    to VGA Adapter, the LAPTOP (13" Macbook pro) will show the second
    monitor as a VGA monitor, while it shows the Laptops's own as the
    standard LCD one.

    So it clearly detects it is a VGA monitor connected to the
    minidisplayport. Whether it used a different driver, I can't tell.

    Not sure how the newer MiniDisplayPort compares against Mini-Dvi in
    terms of the outputs. Is it just a different plug with same signals, or
    is it really very different ?


    Whether it is a different "driver" I can't tell. But the OS clearly knew
    this was a VGA output, despite coming out of a Mini-DVI port.
     
    JF Mezei, Jul 16, 2009
    #4
  5. notme

    notme Guest

    > What problem are you trying to solve?

    When VNC'ing into a Mac Mini (Mini has 10.5.7), I cannot see data in Apple
    Numbers spreadsheets. They appear blank (all menus work, all features of the
    spreadsheet function -- there's just no data displayed). The spreadsheet
    prints and shows the data OK.

    The author of the VNC client tells me that it's probably because of the
    default display driver. He suggests plugging in a monitor or emulating one. I
    am moving house and have nothing (my monitors and most everything else is
    2000 miles away) other than the Mini and an old PowerBook G3/400 (w/ 10.4.11)
    that I'm using for the VNC client.

    I tried another "brand" of VNC client with the same results.

    I tried changing numbers of colors and display resolution with no results.

    not
     
    notme, Jul 17, 2009
    #5
  6. notme

    notme Guest

    > followed by a DVI Detective might do it.
    > <http://www.gefen.com/kvm/dproduct.jsp?prod_id=4714>


    Yow! $80. Hmm...

    Well, if I can't find a simpler way, I'll look into this.

    Thanks.

    Dave
     
    notme, Jul 17, 2009
    #6
  7. notme

    Doc O'Leary Guest

    In article
    <-september.org>,
    notme <> wrote:

    > > followed by a DVI Detective might do it.
    > > <http://www.gefen.com/kvm/dproduct.jsp?prod_id=4714>

    >
    > Yow! $80. Hmm...
    >
    > Well, if I can't find a simpler way, I'll look into this.


    The DVI-to-Video adaptor is only $20, and I'm guessing it doesn't need
    to query a TV to provide the composite signal.

    --
    My personal UDP list: 127.0.0.1, localhost, googlegroups.com, ono.com,
    and probably your server, too.
     
    Doc O'Leary, Jul 17, 2009
    #7
  8. notme

    notme Guest

    On Fri, 17 Jul 2009 08:39:21 -0700, Doc O'Leary wrote
    (in article <>):

    > The DVI-to-Video adaptor is only $20, and I'm guessing it doesn't need
    > to query a TV to provide the composite signal.


    Good idea. Any favorite makes / models?

    Thanks.
     
    notme, Jul 18, 2009
    #8
  9. notme

    notme Guest

    > Have you tried opening the spreadsheet in a brand-new Mac OS X user
    > account to see if the problem is local to that user account?


    Spreadsheet appears identical regardless what user opens it on this Mini via
    VNC.

    > Have you tried placing the spreadsheet on another computer that you can
    > access remotely with VNC to see if perhaps the problem is local to the
    > Mac mini?


    No other computers available. I'm moving house and all my tools & stuff is
    2000 miles away.

    > I would be extremely interested in seeing a screen shot so that I know
    > exactly what you are describing is what I imagine from your description.


    <http://i29.tinypic.com/2ebcric.jpg>

    I can access all menus and buttons on the window. Note the term "Rent" in the
    edit field just below the Format Bar. This shows the content of the current
    cell, and changes as I use the arrow keys to scroll around the (invisible)
    cells of the spreadsheet, so I know the data exists.

    Printing works as it should and shows a normal spreadsheet populated with
    data.

    Thanks.
     
    notme, Jul 18, 2009
    #9
  10. notme

    Chris Ridd Guest

    On 2009-07-18 06:09:43 +0100, notme <> said:

    >> Have you tried opening the spreadsheet in a brand-new Mac OS X user
    >> account to see if the problem is local to that user account?

    >
    > Spreadsheet appears identical regardless what user opens it on this Mini via
    > VNC.
    >
    >> Have you tried placing the spreadsheet on another computer that you can
    >> access remotely with VNC to see if perhaps the problem is local to the
    >> Mac mini?

    >
    > No other computers available. I'm moving house and all my tools & stuff is
    > 2000 miles away.
    >
    >> I would be extremely interested in seeing a screen shot so that I know
    >> exactly what you are describing is what I imagine from your description.

    >
    > <http://i29.tinypic.com/2ebcric.jpg>
    >
    > I can access all menus and buttons on the window. Note the term "Rent" in the
    > edit field just below the Format Bar. This shows the content of the current
    > cell, and changes as I use the arrow keys to scroll around the (invisible)
    > cells of the spreadsheet, so I know the data exists.
    >
    > Printing works as it should and shows a normal spreadsheet populated with
    > data.


    That's a pretty interesting way for Numbers to fail, and I'm wondering
    if it is using Quartz in some way that VNC isn't supporting.

    Which VNC server and client are you using? Have you tried different
    clients? (Not sure if you can run a different VNC server...)

    If you've got Xcode installed, can you run
    /Developer/Applications/Graphics Tools/Quartz Debug.app and play with
    the Disable Quartz Extreme/Enable QuartzGL menu items? I think you need
    to restart Numbers after making these changes.

    --
    Chris
     
    Chris Ridd, Jul 18, 2009
    #10
  11. notme

    Doc O'Leary Guest

    In article
    <-september.org>,
    notme <> wrote:

    > On Fri, 17 Jul 2009 08:39:21 -0700, Doc O'Leary wrote
    > (in article <>):
    >
    > > The DVI-to-Video adaptor is only $20, and I'm guessing it doesn't need
    > > to query a TV to provide the composite signal.

    >
    > Good idea. Any favorite makes / models?


    I was just talking about what the Apple Store has available. You could
    probably find cheaper at any computer shop, especially if you're not
    really going to use it.

    --
    My personal UDP list: 127.0.0.1, localhost, googlegroups.com, ono.com,
    and probably your server, too.
     
    Doc O'Leary, Jul 18, 2009
    #11
  12. notme

    notme Guest

    On Sat, 18 Jul 2009 09:05:11 -0700, Doc O'Leary wrote
    (in article <>):

    > I was just talking about what the Apple Store has available. You could
    > probably find cheaper at any computer shop, especially if you're not
    > really going to use it.


    You mean? ::

    <http://tinyurl.com/kmqcbu>
     
    notme, Jul 18, 2009
    #12
  13. notme

    Tim Murray Guest

    On Thu, 16 Jul 2009 16:15:23 -0400, notme wrote:
    > Apparently different video drivers are loaded depending on if a monitor is
    > connected or not. This is the case when connecting via VNC to a "headless"
    > Mac Mini.
    >
    > Using just a Mini-DVI-to-VGA adapter won't load another driver.
    >
    > Is there a way to emulate a monitor connection?
    >
    > Is this a case of I^2C communication? Any simpler method?
    >
    > Thanks.
    > N.
    >


    I saw the screen shot, and that's certainly odd. I'm thinking Quartz is doing
    something VLC doesn't like. If you have two people available, one at each
    machine, try YuuGuu or www.acrobat.com > connect now. Both are free.
     
    Tim Murray, Jul 19, 2009
    #13
  14. notme

    Chris Ridd Guest

    On 2009-07-20 08:17:54 +0100, notme <> said:

    > On Sun, 19 Jul 2009 08:27:43 -0700, Tim Murray wrote
    > (in article <>):
    >
    >> I saw the screen shot, and that's certainly odd. I'm thinking Quartz is doing

    >
    >> something VLC doesn't like. If you have two people available, one at each
    >> machine, try YuuGuu or www.acrobat.com > connect now. Both are free.

    >
    > My problem -- and the reason I started using VNC -- is that all (2 of them)
    > of my monitors are with all my tools and other stuff, 2000 miles away. The
    > "host" mac (server) is a headless Mini. So even if someone would sit at the
    > Mini, there's nothing to report.


    Have you tried different VNC clients, including Apple's Remote Desktop?
    If no clients can see your Numbers spreadsheet, then the bug's likely
    to be in the VNC server.

    --
    Chris
     
    Chris Ridd, Jul 20, 2009
    #14
  15. notme

    notme Guest

    On Mon, 20 Jul 2009 03:34:17 -0700, Chris Ridd wrote
    (in article <>):

    > Have you tried different VNC clients, including Apple's Remote Desktop?
    > If no clients can see your Numbers spreadsheet, then the bug's likely
    > to be in the VNC server.


    At US$300 for ARD, I could go buy a monitor (2 or 3) to plug into the Mini
    and solve the issue.
     
    notme, Jul 20, 2009
    #15
  16. notme

    Chris Ridd Guest

    On 2009-07-20 14:27:52 +0100, notme <> said:

    > On Mon, 20 Jul 2009 03:34:17 -0700, Chris Ridd wrote
    > (in article <>):
    >
    >> Have you tried different VNC clients, including Apple's Remote Desktop?
    >> If no clients can see your Numbers spreadsheet, then the bug's likely
    >> to be in the VNC server.

    >
    > At US$300 for ARD, I could go buy a monitor (2 or 3) to plug into the Mini
    > and solve the issue.


    Yeah, but what about the other free clients? It mght be worth trying
    this out in an Apple Store too, if you can reach one.
    --
    Chris
     
    Chris Ridd, Jul 20, 2009
    #16
  17. notme

    notme Guest

    On Mon, 20 Jul 2009 06:59:09 -0700, Chris Ridd wrote
    (in article <>):

    > Yeah, but what about the other free clients?


    Both JollysFastVNC and Chicken Of The VNC give identical results.
     
    notme, Jul 20, 2009
    #17
  18. notme

    notme Guest

    > Have you tried doing this yet?:
    >
    > <http://soerennielsen.dk/mod/VGAdummy/index_en.php>


    Thanks for the creative suggestion.

    I just made up one tonight and plugged it into the Mini. It had an effect, if
    not the one I expected.

    When I plug in the "dummy" connector and reboot, I cannot connect to the Mini
    via VNC at all. (Tried different clients; no joy.)

    If I unplug the dummy, the mini behaves as before; VNC connectivity is
    restored.

    ???

    Thanks.
     
    notme, Jul 22, 2009
    #18
  19. notme

    IanM Guest

    notme wrote:
    >> Have you tried doing this yet?:
    >>
    >> <http://soerennielsen.dk/mod/VGAdummy/index_en.php>

    >
    > Thanks for the creative suggestion.
    >
    > I just made up one tonight and plugged it into the Mini. It had an effect, if
    > not the one I expected.
    >
    > When I plug in the "dummy" connector and reboot, I cannot connect to the Mini
    > via VNC at all. (Tried different clients; no joy.)
    >
    > If I unplug the dummy, the mini behaves as before; VNC connectivity is
    > restored.
    >
    > ???
    >
    > Thanks.
    >

    Sounds like its getting stuck before the VNC server starts. Probably
    because its got a dialog box up resulting from the monitor change. Can
    you set the resolution to 640x480 via VNC and try again?


    As all ID pins open was originally defined as 'no monitor', it would
    also be worth connecting pin 11 (ID0) to pin 5 (GND) to properly
    identify your connector as a colour VGA monitor.

    I don't think grounding pin 4 (ID2) will help as I doubt the Mac
    supports IBM 8514/A displays :) It is worth a try though if you
    already have it working at 640x480 to see if you can then switch to
    1024x768.

    You *will* need the I2C eeprom if you want to emulate a higher
    resolution monitor.



    --
    Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
    ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
    [at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL:
     
    IanM, Jul 22, 2009
    #19
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