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RE: Touch Screen Question

From: Doug Sutherland <>
Date: Thu, 03 Apr 2003 17:29:24 +0200

Jeremy,

 > Doug you kick ass.

My friend has a t-shirt that says
"equal opportunity ass kicker" <g>

 > I probably am not going to use a SBC I am probably gonna
 > go with the VIA EPIA board.... so what shoulf I be looking for.

The VIA EPIA Manual is here:
http://www.viavpsd.com/product/3/4/EPIA-M_Manual_v1.0.pdf

At first I thought this board didn't support flat panels,
but the manual says "1 connector for LVDS module (optional).
This board doesn't appear to have flat panel connector like
most embedded boards. It looks like it's assumed that people
will connect to analog VGA or TV (NTSC) devices.

If you want really crisp and nice flat panel output, I
suggest that you find this "LVDS module" and mate that
with the EPIA ... the module is an LVDS transmitter.

See this paper on LVDS ...
http://www.9xmedia.com/Pages/Technology%20-%20LVDS.html

With the appropriate LVDS module, you can connect EPIA
to flat panels that support LVDS ... however there still
might be an issue of pinout/pin mapping (I'm not sure
because I still haven't tried LVDS but will be doing
that soon).

With EPIA you only have three options: analog VGA,
TV (NTSC) output, and LVDS to flat panel. Most of the
HMDs including Tekger M1 and MicroOptical SV-3 accept
analog VGA inputs, so you can use either of those with
the analog VGA port. The M1 can also be driven by a
smaller driver using the TV out signal (RS170 module).
For flat panel support, you either need an LVDS
module for that board or an LCD controller board
that accepts analog VGA and converts to digital.
Earth LCD has some of those (see below) but they
are not small and they tend to use a lot of power.

http://www.earthlcd.com/controllers.htm

 > TFT LCD.. Touch screen overlay that will work as a
 > mouse, and what kind of connection? VGA?

LCDs that already have integrated touch screens are
very expensive (except for small PDA screens but that
is a different world, they are really designed to
connect to processors like SA-1110 etc and support
only QVGA, which usually is NOT supported on x86
boards). Therefore, it's more economical to find a
nice flat panel without touch screen and add an
overlay (they are available in different sizes).
For connection (signal), I think that LVDS is the
best way to go. Keep in mind that "VGA" can mean
different things .... the "VGA port" (15-pin DSUB
connector) is ANALOG ... it will NOT drive an LCD
(which is DIGITAL) without extra hardware. This is
why most SBCs have BOTH analog VGA ports and flat
panel connectors (digital). It's kind of sad IMO
but mating an LCD with SBC is not all that easy
unless you go with big/bulky/power hungry and
expensive parts. I'm still eyeing the Toshiba
4 inch VGA display ... which does 200 pixels per
inch ... I want to try that ...

http://wearables.blu.org/wear-hard-02/20027037.html

Hope this helps ...

   -- Doug

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