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RE: Touch Screen Question

Doug you kick ass. ok. 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. TFT LCD..
Touch screen overlay that will work as a mouse, and
what kind of connection? VGA?

-----Original Message-----
From: Doug Sutherland [mailto:]
Sent: Wednesday, April 02, 2003 6:39 AM
To: 
Subject: RE: Touch Screen Question

Jeremy,

 > Hmm I guess I will have write and find out if this will work as a mouse.
 > http://www.earthlcd.com/sbc.htm

 From their web site ...

How does the touchscreen work? The 3M (formerly Dynapro) touch drivers
will work under all windows operating systems. The touch controller is
compatible with the Dynapro SC3 controller. The driver under windows
replaces the mouse so most software is already touch compatible if it
used the mouse!

http://www.earthlcd.com/KIT_S78_SBC.htm

You need to be careful with LCDs though ... the first question is what
SBC are you connecting to ... even though this is "VGA" it is digital
VGA and its STN signals ... it needs to be driven by a graphics
controller that supports these signals. Some things to note about
this particular LCD ...

First of all, STN is not the best of displays ... they tend to be
quite dim in comparison to TFT (thin film transistor). The best
displays are active matrix TFT ... note this comment ...

Can I use this in my Car? NO. Unless you don't want video and your car
is going to be inside for show use only. This screen is about 80 nits
and we reccommend at least 200 nits for car use because of the high
ambient light (sunlight!)

Also note this comment ...

Can I use this for Video? No the number of colors(256) an screen
response time (300ms) is unacceptable for video.

How about Photographs? Depending on your software yes. This type
of display is used in electronic picture frames. Usually the jpeg
images have dithering in them. Unmodified images and different
viewing software will have different results.

(this is a very low end display for indoor still images ...)

Finally, and the most important, is this ...
What single board computers will this kit work with? We put the 44 pin
2 millimeter header that matches many Advantech and Aeeon single board
computers. We will update this page with the pin out soon and the SBC's
our customers have tested this with.

The Advantech boards do have a 44-pin 2mm connector (same as laptop
hard drive), but to say generically "the type with 44-pin connector"
is a scary statement ... there are MANY different pinouts on various
SBCs ... most often you need to make a custom cable (like this) ...

http://home.earthlink.net/~wearable/images/fashion-lcd-custom-cable-large.jp
g
http://home.earthlink.net/~wearable/galleria/fashion/

If I was shopping for an LCD ... and an SBC ... I would look for
LVDS connection rather than standard digital wiring ... because
you can extend the length of the cable ... and because there are
a smaller number of wires between the SBC (the LVDS transmitter)
and the display. Many LCDs support both LVDS and standard digital
signals. Most LCDs have 30-40 pins, so the cabling is a fairly
important issue ... I have used belkin printer cables in the past
because they are round and clean, but the length can only go
about 18 inches, not too good ... LVDS would be better ...

The other is issue is BIOS support ... the BIOS provides the
proper timings ... sometimes the BIOS needs to be updated to
support a particular display (good luck doing this yourself ...)
This display has a BIOS modification for a particular SBC, and
they have it available for download here ...

http://www.earthlcd.com/downloads/4823/

Sometimes you get lucky and an LCD will work with the standard
VGA BIOS on an SBC ... I got lucky with Advantech PCM-582x and
NEC NL6448AC20-06 display.

I recommend that you start with looking at the SBC specs and
the "supported LCDs" info on the manufacturer web site. Best
case scenario: pick an LCD that is KNOWN to be working, and
where there is pinout mapping available. Otherwise you are
taking a risk that the LCD won't work with the SBC. I have
wired quite a few of these things, often you need to map the
SBC graphic controller pinout info (ie the LCD connector pins)
to a particular LCD and make a custom cable. Most of the SBC
vendors will make a cable for you but it costs big bucks and
you have to send them the LCD. Sometimes they need to do BIOS
updates.

Yes, this is all a real PITA ... like I said look for LCDs
are KNOWN to work with your particular SBC ... do you have
an SBC already? Which? Some companies provide LCD kits for
their SBCs ... those are guaranteed to work ... outside of
that be prepared to spend lots of hours trying to get it
working ... and it may not ever work ...

    -- Doug

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