[ltp] Horizontal interrupt

[linux-thinkpad@linux-thinkpad.org]

---- Daniel <skorka@gmx.net> wrote: 
> On Sat, Sep 22, 2007 at 01:21:46PM -0400, bhaskins@chartermi.net wrote:
> > Does anyone know of a way to pick up the start of the horizontal sweep.
> > Another way to say this is to read or generate an interrupt at the start of the speep(how?).
> > I know that I could pick this off of the vga connector in the back but I would really like to find a cleaner, nicer way.
> 
> Umm... What exactly do you want? Do you want an interrupt everytime the
> card would issue a horizontal sweep (for an analog output) or
I need a pulse at the very start of a new row.

> start transmitting a new row (in case of digital outputs? I do not think
> such a thing is available on most cards, given that it is rather useless
> for most applications. Also keep in mind that at 60 Hz vertical refresh
> and 768 lines,
> this interrupt would trigger at a frequency of 46 kHz.
Plenty enough time for this application.
I am trying to interface a expensive fish finder/depth finder to any 
one of my many Thinkpads.
I have the A/D interface hooked up to my printer port and that part is
working fine except that the display is somewhat ragged because the
transmit control is not in sync with the display.
Thanks,
   Bert 
> 
> regards,
> Daniel
> -- 
> The linux-thinkpad mailing list home page is at:
> http://mailman.linux-thinkpad.org/mailman/listinfo/linux-thinkpad