VGA controller for embedded project?

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I am planning a little hobby-project designing an embedded board around a
ColdFire-processor. (I haven't quite decided exactly which processos yet
though...)
One thing I would like to do is to be able to drive a VGA-display directly
from the board, so I need a VGA-controller.
Are there any good and cheap VGA-controllers that are available for purchase
online?
Any suggestions on a suitable controller, and where to get it, would be
greatly apreciated...

Thanks in advance...

Dala



Re: VGA controller for embedded project?
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What are your other system constraints? If power is not a big issue,
and this is not intended for mass-production, then your easiest route
is probably to use an ISA VGA card. There are not many
embedded-friendly VGA controllers, and they're hard to acquire and
hard to home-prototype with. I would not consider any them
"hobby-project" material.

It is MUCH easier (two orders of magnitude, in terms of time wasted)
to take a micro with a flexible TFT-LCD controller, put DACs on the
outputs, and play games with the dot clock and sync timing registers
to drive analog VGA. This has been done, for example, with the Sharp
LH79520.

My advice, for what it's worth: Don't bother with ColdFire, it's a
legacy architecture. Go for something with a future, like ARM or MIPS.
MIPS if you're an ASIC maven, ARM if you intend to use standard SoC
parts.

Re: VGA controller for embedded project?

"Lewin A.R.W. Edwards"

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directly


Are there ANY "embedded friendly" VGA controlles that are easily available?
I see that ATI, for example, have some controllers intended for embedded
use, but I am not sure where I could buy one.

In what way are these chips hard to home-prototype with?



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In what sense?
Motorola keeps developing the ColdFire and I thougt the latest ColFire
processors were quite powerful and modern.
Is there any particular reason why you consider it "old fashioned"?
I am not familiar with all the different processors, but I was thinking
about the ColdFire because at least I know that some of them have a lot of
nice features, like for example integrated ethernet-, SDRAM-,
USB-controllers, etc.
And the core itself also have for example floating-point, MMU, etc.
Basically everything you need.
If you mean I should consider another architecture instead of ColdFire, can
you give me some examples of some processors you mean would be a better
choice, and which have all of these nice features.


Thanks,

Dala



PS. I have a copy of your book, "Embedded system design on a shoestring."
It's a great book...



Re: VGA controller for embedded project?
Hi,

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Well... The short answer to that is "no". The longer answer to that is
"no, but there are some appliances you could repurpose or scavenge".

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Most VGA controllers, period, are PCI-bus (or AGP), which makes them
fantastically difficult to lash onto an average microcontroller. Most
of them are BGA parts, and hand-prototyping that is NOT a job for the
faint of heart. I've done it, but I'm not proud of it. The parts that
are ISA-bus (or similar) are very limited-production, limited-audience
devices. For example, Epson makes some chips that are suitable, and
they're available in QFP which is possible to home-prototype, but you
will have fun trying to find someplace that will sell you in less than
1 tray (50pcs) quantity. I believe (it's been a while since I was in
the market for these parts...) that Oki and perhaps also NEC make
suitable devices, but last time I tried to get anything out of Oki I
couldn't even find someone who knew that they made the particular
parts I was looking to sample.

You'll also have considerable fun trying to get the chip working,
since the sparse application notes are either incomplete, ambiguous or
plain wrong (in Epson's case, anyway - maybe they cleaned up their act
since I last looked, but anecdotal evidence suggests they haven't).

By and large, consumer electronics don't use separate VGA controllers.
They use on-chip hardware in the main SoC to drive the display,
whatever flavor it might be. So there isn't much market for such
devices, and consequently it's hard to get them at reasonable price in
small quantity.

What is your reason for wanting an external VGA controller, by the
way?

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I'm sorry, I had a bit of a brain hiccup there. When people say
ColdFire, I automatically equate that with 68k parts. Ignore what I
said.

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Thanks :)

Re: VGA controller for embedded project?
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Okay, well, your definition of "hobbyist project" is pretty far
advanced of mine, then :)

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ATI is very hard to deal with. It took us six months of wrestling to
get datasheets. Never managed to get actual parts for sampling, and we
were promising several thousand pieces of orders. I hate to say it,
but the two people that are easiest to deal with are Chips and
Technologies (now Asiliant), and Epson. The downside to Asiliant's
parts is that they are really ancient, and you'll probably have to do
some finagling to interface them to current micros. Really they are
for legacy applications. But they are very generous with samples, and
their app notes sort of mostly work.

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I dunno... I still think you're approaching a very difficult problem.
I've had a lot of experience trying to get high-resolution
(1280x1024x24bpp was my target) displays integrated onto embedded
systems - though, my focus was on LVDS LCD interface, not analog VGA.
The ONLY cost-effective method I ever found was to buy an x86-based
SBC with an appropriate laptop LCD/CRT controller on it.

Re: VGA controller for embedded project?
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Another option:

Use an Altera FPGA evaluation card, run the Nios processor, and put
the VGA controller in the FPGA. The Lancelot add on card has a
VGA, mouse, audio, and keyboard interface. http://www.fpga.nl

The whole thing (evaluation card and Lancelot) is about the size of a
small book and also has RAM, Flash, Ethernet, etc.

That certainly wouldn't be a legacy architecture. If it becomes one,
program the FPGA with a different CPU. ;-)

-Rich
--
Richard Pennington
Email: snipped-for-privacy@pennware.com
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Re: VGA controller for embedded project?
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If you need Scale-able Text, we have a solution at
http://www.designtools.co.nz/vga_232.htm

This uses a simple RS232 link, so can be remote from the embedded
controller.

-jg


Re: VGA controller for embedded project?

"Jim Granville"

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purchase


Thanks for your tip, but it is not quite what I was thinking about.
Firstly, I would like to have better resolution, maybe as much as 1600 x
1200.
But what is most important is that the controller is not a "separate
module", I am looking for a controller-chip that can be soldered onto my own
PCB.



Anyway, thanks for your answer.

Dala



Re: VGA controller for embedded project?

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1600x1200, that about 200Mhz Pixel Clock,

With 24bpp at 85Hz, that's a about 470Mb/s  memory bandwidth just to take data
from framebuffer to the DACs.


So I'd say with a FPGA like Spartan 3, two 16bits DDR at 133Mhz (thats 1066Mb/s
bandwidth ), I think it's doable.

With 1280x1024 that would be easier. 75Hz would be ok to have not too much
flicker, About 120Mhz pixel clock, 300Mb/s bandwidth.
With a singe DDR chip you'd have 566Mb/s bandwidth and should be ok to display
like 30 fps.



Sylvain

Re: VGA controller for embedded project?
Dala Dahlgren schrieb:
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You might take a look at the LCD-controllers from EPSON
http://www.eea.epson.com /
You can add a RAMDAC to the  S1D13504  for example to get standard VGA
signal.

HTH
Markus

Re: VGA controller for embedded project?

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Just because I didn't see this remarks yet in this thread, so:

a.) why not just an small FPGA & SDRAM for a VGA controller ?
You probably need some "glue" logic anyway ...

b.) Look in the automotive sections of the big guys (NEC/Toshiba/...)
They have some display controllers, never mention the "VGA" but can
drive crt & lcd fine. Don't know if it is 1200x1024 so ...

just my .000001 cents ;-)



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