Design a VGA control board for an LCD.

[[email protected]]

Hi,

I currently have an 21" NEC LCD that can handle 1280x1024 of
resolution. I'd like to build a simple card to accept VGA signal and
control the LCD after that.

I saw some off-the-shelf controller card, but they seem to be expensive
and not very widely available for ordering.

Is there other off-the-shelf IC or card that can do such a thing ?

Thanks.

 

[Christopher Ott]

Hi,

I currently have an 21" NEC LCD that can handle 1280x1024 of
resolution. I'd like to build a simple card to accept VGA signal and
control the LCD after that.

I saw some off-the-shelf controller card, but they seem to be expensive
and not very widely available for ordering.

Is there other off-the-shelf IC or card that can do such a thing ?

Thanks.

I'm not entirely clear what you're after. Are you saying that you just have
the glass and want the interface card, or do you have the whole monitor
without a VGA input?

Digital View makes interface cards
http://www.digitalview.com/controllers/products.php however I'm not too sure
of the current pricing, or availability in small quantities. I redesigned
the model MAV-1280 LCD card for them in early 2000 to get it to pass CE, and
I can tell you that there is nothing simple about it. You will also need the
inverter board to operate the backlight.

If you know of a monitor which uses that glass, you could look for a broken
one on eBay to get the driver boards.

Chris

 

[Don McKenzie]

I'm not entirely clear what you're after. Are you saying that you just have
the glass and want the interface card, or do you have the whole monitor
without a VGA input?

Digital View makes interface cards
http://www.digitalview.com/controllers/products.php however I'm not too sure
of the current pricing, or availability in small quantities. I redesigned
the model MAV-1280 LCD card for them in early 2000 to get it to pass CE, and
I can tell you that there is nothing simple about it. You will also need the
inverter board to operate the backlight.

If you know of a monitor which uses that glass, you could look for a broken
one on eBay to get the driver boards.

Chris

not 100% sure of the question either, but here is a potential answer:
http://www.dontronics.com/micro-vga.html

Don...


--
Don McKenzie
E-Mail Contact Page: http://www.dontronics.com/e-mail.html

Micro,TTL,USB to 1.5" color LCD http://www.dontronics.com/micro-lcd.html
USB,RS232 or TTL to VGA Monitor http://www.dontronics.com/micro-vga.html
World's smallest USB 2 TTL Conv http://www.dontronics.com/micro-usb.html

 

[[email protected]]

I have a NEC NL128102AC31-02 LCD. This would describe what it is:

http://www.stobby.co.uk/RDS/nec-dl.asp?f=NL128102AC31-02.pdf

I think it's almost VGA ready, unless...

Thanks for your responses so far.

 

[[email protected]]

Actually, mine is the version 01 instead of 02 of the LCD, this link is
better:

http://www.beyondinfinite.com/lcd/Library/Nec/NL128102AC31-01.pdf

It now seems to boil down to how to generate the "dot clock" signal
from the VGA signals .

Any comments ?

Thanks,

 

[lemonjuice]

Actually, mine is the version 01 instead of 02 of the LCD, this link is
better:

http://www.beyondinfinite.com/lcd/Library/Nec/NL128102AC31-01.pdf

It now seems to boil down to how to generate the "dot clock" signal
from the VGA signals .

Any comments ?

Thanks,

Well the options are many ... a few bucks of some components of an
LC tank oscillator with a quartz crystal will get you your dot clock.
Any PC with an average VGA card can generate for you a dot clock
signal. Zdnet once had a basic program for download that could do that
so if you hunt for that you can play around with all the
possibilities.

It would seem though you need more then a dot clock oscillator ...
Your monitor specs indicates that it uses differential low voltage
signals for video input ... The interfaces for such are usually
expensive but Kontron produce(d) one of those starting at 72 dollars
which is cheap. Try the following url
http://us.kontron.com/index.php?id=82&cat=640&source=Searchengine


lemonjuice

 

[[email protected]]

Sorry for being confusing at the begining, but the monitor version 01
does use the analog RGB. The link for Kontron shows interesting
products.

What if I like to use the monitor on a generic VGA device (tuner..) not
sure the dot clock signal is easily found. Even on a PC VGA card, would
it feasible to carry it (100 Mhz signal) along the cable ?

Thanks,

 

[lemonjuice]

Sorry for being confusing at the begining, but the monitor version 01
does use the analog RGB. The link for Kontron shows interesting
products.

What if I like to use the monitor on a generic VGA device (tuner..) not
sure the dot clock signal is easily found. Even on a PC VGA card, would
it feasible to carry it (100 Mhz signal) along the cable ?

Thanks,

Looking at the attachment would seem to indicate that the monitor
accepts TTL level RGB inputs. If that is the case then you wouldn't
see anything because analogue RGB inputs are lower voltage levels
then the TTL ones.
However some thinking plus extra circuit components will somewhat
clear the problem.

Normally what travels on your video cable is the output from your
Random Access Memory Digital to Analog Converter on your video card
which is normally a seperate chip though sometimes it is incorporated
in your Video processor. The frequency given is always the "maximum"
frequency which depends on seperate circuitry that generates the dot
clock signal on the VGA adapter. Many modern video adapters though
have different dot clock signal generators. The actual frequency will
always be lower as it is a function of monitor settings like refresh
rate etc. 100Mhz looks quite feasible. It is actually true that to
maximise your visual experiance you have to match your monitors
bandwidth to the dot clock frequency but then that is another subject.

lemonjuice

 

[Joel Kolstad]

Normally what travels on your video cable is the output from your
Random Access Memory Digital to Analog Converter on your video card
which is normally a seperate chip though sometimes it is incorporated
in your Video processor.

I'd venture that almost any video card you could purchase today would have an
integrated ADC; outboard ADCs haven't been common (at least in "run of the
mill" video cards) for many years now.

Dot clocks are often above 100MHz as well... a 1600x1200 60Hz display is
144MHz, and about the highest resolution monitors that still have analog
inputs are probably 1920x1200 @ 75Hz = 172.8MHz.

---Joel

 

[lemonjuice]

I'd venture that almost any video card you could purchase today would have an
integrated ADC; outboard ADCs haven't been common (at least in "run of the
mill" video cards) for many years now.

You don't seem to have noticed I was talking about Digital to Analog
converter and not Analog to Digital converters.

BTW what is the deal with ADC ... most modern monitors use Analog
input signals.

And the Op's monitor has an Analog input signal.

Dot clocks are often above 100MHz as well... a 1600x1200 60Hz display is
144MHz,

More like 1600*1200*60 =115.2Hz
No deal though talking about a 1600x1200 resolution when the Op's
monitor goes up only to 1280x1024

and about the highest resolution monitors that still have analog
inputs are probably 1920x1200 @ 75Hz = 172.8MHz.

Still higher resolution?
However this calculation doesn't take into account the blanking times
of the horizontal and vertical scan which gets you a completely
different dot clock frequency.

---Joel

lemonjuice

 

[Jerry R]

Actually, mine is the version 01 instead of 02 of the LCD, this link is
better:

http://www.beyondinfinite.com/lcd/Library/Nec/NL128102AC31-01.pdf

It now seems to boil down to how to generate the "dot clock" signal
from the VGA signals .

Any comments ?

Thanks,

[snip]

Analog Devices makes several chips that will generate dotclock from RGBHV.
It's their AD988x series.

....jerry