OMAP, nice! but will be an overkill for our application

Gus

--- In l..., "Paul Curtis" wrote:
>
> Hi,
>
> > Is there an LCD to VGA ready-made circuits out there? (basically
> > FPGA+RAM)
> >
> > I was able to generate VGA 640x480 timing using an LPC2478. This greatly
> > slowed down the system, due to the high load on SDRAM.
> > Now, to go to higher resolutions, it is not much of an option on
> > LPC2478. I have seen a VGA frame generator chip before that have built
> > in frame buffer and then you can use LPC248 to clock 1024x768 at low
> > frequency to the chip and then the chip will take care of generating the
> > high speed XVGA timings. It found only one company but I was not able to
> > get any communication back from them!
> >
> > IS there someone that offers a circuit (FPGA/RAM) to take in the LCD
> > signals at low clock rate (4Mhz maybe) and then this circuit will buffer
> > the data on RAM then take the same data and generate the required
> > timings?
> >
> > My understanding is that this can be easily done using FPGA but I know
> > thing about FPGA!
>
> Why not use an OMAP or iMX51, these support HDMI... It's a step up, I
> would grant you. ;-)
>
> -- Paul.
>
> --
> Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
> CrossWorks V2 is out for LPC1700, LPC3100, LPC3200, SAM9, and more!
>

We have a large application that runs from internal flash+SDRAM and most variables are in SDRAM so yes using LCD is slowing down the system.

I have done a lot of experiments and know what LPC can/can't do. All I am looking for is a frame generator circuit that will take 1024x768 from LPC2478 at low clock rate, maybe 4Mhz and then the circuit will buffer the frame-buffer and send it to VGA monitor at standard clock rate (over 60Mhz)

There are already chips that do that but I only found one company, which is not responding!

Gus

--- In l..., "Tim Mitchell" wrote:
>
> ----Original Message----
> From: l...
> [mailto:l...] On Behalf Of Mike Harrison
> Sent: 08 February 2010 10:27 To: l...
> Subject: Re: [lpc2000] VGA frame generator
>
> > On Mon, 8 Feb 2010 09:52:53 -0000, you wrote:
>
> > > LPC2478 can do 1024x768, it should not "greatly slow
> > > down the system" as it's all hardware ...
> >
> > But the SDRAM bus is shared with LCD access, so a high
> > bandwidth LCD load will slow down anything that needs to
> > use the SDRAM
>
> Yes, it does share the bus, but the SDRAM contention is only noticeable
> if you copy large blocks using memcpy. In normal operation it doesn't
> make much difference. This is why I wondered what he was going to be
> doing with it, if you're shifting blocks of graphics around it can have
> an impact.
>
> --
> Tim Mitchell
>

yes you can do 1024x768 on an LCD but *NOT* on a VGA monitor. You will need a clock of 60Mhz++!

Even whne I run it at 640x240 on a VGA monitor, I need 25Mhz which really slows down the system.... the problem is not in the resolution but in the high clock speed.

Gus

--- In l..., "Tim Mitchell" wrote:
>
> ----Original Message----
> From: l...
> [mailto:l...] On Behalf Of The G Man
> Sent: 07 February 2010 18:43 To: l...
> Subject: [lpc2000] VGA frame generator
>
> > Hello,
> >
> > Is there an LCD to VGA ready-made circuits out there?
> > (basically FPGA+RAM)
> >
> > I was able to generate VGA 640x480 timing using an
> > LPC2478. This greatly slowed down the system, due to the
> > high load on SDRAM.
> > Now, to go to higher resolutions, it is not much of an
> > option on LPC2478. I have seen a VGA frame generator chip
> > before that have built in frame buffer and then you can
> > use LPC248 to clock 1024x768 at low frequency to the chip
> > and then the chip will take care of generating the high
> > speed XVGA timings. It found only one company but I was
> > not able to get any communication back from them!
> >
> > IS there someone that offers a circuit (FPGA/RAM) to take
> > in the LCD signals at low clock rate (4Mhz maybe) and
> > then this circuit will buffer the data on RAM then take
> > the same data and generate the required timings?
> >
> > My understanding is that this can be easily done using
> > FPGA but I know thing about FPGA!
>
> LPC2478 can do 1024x768, it should not "greatly slow down the system" as
> it's all hardware ... Herbert Demmel on this list has done it.
> Solomon do a wide range of standalone LCD controller chips if you want
> something standalone but then you have an added problem of transferring
> the graphics data into the controller chip. At least on the LPC2478 the
> graphics buffer is part of the system ram.
>
> You don't say what you are trying to display on the LCD?
>
> --
> Tim Mitchell
>

There is this componenless vga project in the mbed project here:

http://mbed.org/projects/cookbook/

I have been waiting for the author to release the details but nothing yet.
--- In l..., groups@... wrote:
>
> Tim Mitchell schrieb:
> > ----Original Message----
> > From: l...
> > [mailto:l...] On Behalf Of The G Man
> > Sent: 07 February 2010 18:43 To: l...
> > Subject: [lpc2000] VGA frame generator
> >
> >
> >> Hello,
> >>
> >> Is there an LCD to VGA ready-made circuits out there?
> >> (basically FPGA+RAM)
> >>
> >> I was able to generate VGA 640x480 timing using an
> >> LPC2478. This greatly slowed down the system, due to the
> >> high load on SDRAM.
> >> Now, to go to higher resolutions, it is not much of an
> >> option on LPC2478. I have seen a VGA frame generator chip
> >> before that have built in frame buffer and then you can
> >> use LPC248 to clock 1024x768 at low frequency to the chip
> >> and then the chip will take care of generating the high
> >> speed XVGA timings. It found only one company but I was
> >> not able to get any communication back from them!
> >>
> >> IS there someone that offers a circuit (FPGA/RAM) to take
> >> in the LCD signals at low clock rate (4Mhz maybe) and
> >> then this circuit will buffer the data on RAM then take
> >> the same data and generate the required timings?
> >>
> >> My understanding is that this can be easily done using
> >> FPGA but I know thing about FPGA!
> >>
> >
> > LPC2478 can do 1024x768, it should not "greatly slow down the system" as
> > it's all hardware ... Herbert Demmel on this list has done it.
> >
> I've done 1024 x 600 (not 768) and would like you to keep in mind, that
> the frame refresh rate is only about a bit more than 30 fps, as the
> maximum pixel refresh rate which can be done with the LPC2478 is 24 MHz
> only (possibly 48 MHz with 32-bit SDRAM, I did not test it with 32 bits).
>
> Most TFTs do support 60 Hz +/- 5 Hz frame refresh rate only, the one we
> use luckily goes down to 25 Hz enabling us to realize this project. We
> are using a 16-bit wide SDRAM causing a bandwidth usage of about 65% for
> display refreshing (according to the bandwidth calculator available on
> NXP's website), we are operating the TFT in 16 bit color mode.
>
> As we run the complete program in the flash memory and have nearly all
> variables and buffers in the internal SRAM, the performance of the whole
> system is unbelievable good for a 72 MHz controller with a (dumb)
> built-in display controller. The only drawback I can see is that we need
> to go down to 4.5 MHz for the SD card interface to avoid flickering
> during SD card reading / writing.
>
> Hope that helps you to estimate "what can be done with a LPC2478".
>
> Have a nice day
> Herbert
>

Tim Mitchell schrieb:
> ----Original Message----
> From: l...
> [mailto:l...] On Behalf Of The G Man
> Sent: 07 February 2010 18:43 To: l...
> Subject: [lpc2000] VGA frame generator
>
>
>> Hello,
>>
>> Is there an LCD to VGA ready-made circuits out there?
>> (basically FPGA+RAM)
>>
>> I was able to generate VGA 640x480 timing using an
>> LPC2478. This greatly slowed down the system, due to the
>> high load on SDRAM.
>> Now, to go to higher resolutions, it is not much of an
>> option on LPC2478. I have seen a VGA frame generator chip
>> before that have built in frame buffer and then you can
>> use LPC248 to clock 1024x768 at low frequency to the chip
>> and then the chip will take care of generating the high
>> speed XVGA timings. It found only one company but I was
>> not able to get any communication back from them!
>>
>> IS there someone that offers a circuit (FPGA/RAM) to take
>> in the LCD signals at low clock rate (4Mhz maybe) and
>> then this circuit will buffer the data on RAM then take
>> the same data and generate the required timings?
>>
>> My understanding is that this can be easily done using
>> FPGA but I know thing about FPGA!
>>
>
> LPC2478 can do 1024x768, it should not "greatly slow down the system" as
> it's all hardware ... Herbert Demmel on this list has done it.
>
I've done 1024 x 600 (not 768) and would like you to keep in mind, that
the frame refresh rate is only about a bit more than 30 fps, as the
maximum pixel refresh rate which can be done with the LPC2478 is 24 MHz
only (possibly 48 MHz with 32-bit SDRAM, I did not test it with 32 bits).

Most TFTs do support 60 Hz +/- 5 Hz frame refresh rate only, the one we
use luckily goes down to 25 Hz enabling us to realize this project. We
are using a 16-bit wide SDRAM causing a bandwidth usage of about 65% for
display refreshing (according to the bandwidth calculator available on
NXP's website), we are operating the TFT in 16 bit color mode.

As we run the complete program in the flash memory and have nearly all
variables and buffers in the internal SRAM, the performance of the whole
system is unbelievable good for a 72 MHz controller with a (dumb)
built-in display controller. The only drawback I can see is that we need
to go down to 4.5 MHz for the SD card interface to avoid flickering
during SD card reading / writing.

Hope that helps you to estimate "what can be done with a LPC2478".

Have a nice day
Herbert

----Original Message----
From: l...
[mailto:l...] On Behalf Of Mike Harrison
Sent: 08 February 2010 10:27 To: l...
Subject: Re: [lpc2000] VGA frame generator

> On Mon, 8 Feb 2010 09:52:53 -0000, you wrote:

> > LPC2478 can do 1024x768, it should not "greatly slow
> > down the system" as it's all hardware ...
>
> But the SDRAM bus is shared with LCD access, so a high
> bandwidth LCD load will slow down anything that needs to
> use the SDRAM

Yes, it does share the bus, but the SDRAM contention is only noticeable
if you copy large blocks using memcpy. In normal operation it doesn't
make much difference. This is why I wondered what he was going to be
doing with it, if you're shifting blocks of graphics around it can have
an impact.

--
Tim Mitchell

On Mon, 8 Feb 2010 09:52:53 -0000, you wrote:

>----Original Message----
>From: l...
>[mailto:l...] On Behalf Of The G Man
>Sent: 07 February 2010 18:43 To: l...
>Subject: [lpc2000] VGA frame generator
>
>> Hello,
>>
>> Is there an LCD to VGA ready-made circuits out there?
>> (basically FPGA+RAM)
>>
>> I was able to generate VGA 640x480 timing using an
>> LPC2478. This greatly slowed down the system, due to the
>> high load on SDRAM.
>> Now, to go to higher resolutions, it is not much of an
>> option on LPC2478. I have seen a VGA frame generator chip
>> before that have built in frame buffer and then you can
>> use LPC248 to clock 1024x768 at low frequency to the chip
>> and then the chip will take care of generating the high
>> speed XVGA timings. It found only one company but I was
>> not able to get any communication back from them!
>>
>> IS there someone that offers a circuit (FPGA/RAM) to take
>> in the LCD signals at low clock rate (4Mhz maybe) and
>> then this circuit will buffer the data on RAM then take
>> the same data and generate the required timings?
>>
>> My understanding is that this can be easily done using
>> FPGA but I know thing about FPGA!
>
>LPC2478 can do 1024x768, it should not "greatly slow down the system" as
>it's all hardware ...

But the SDRAM bus is shared with LCD access, so a high bandwidth LCD load will slow down anything
that needs to use the SDRAM

----Original Message----
From: l...
[mailto:l...] On Behalf Of The G Man
Sent: 07 February 2010 18:43 To: l...
Subject: [lpc2000] VGA frame generator

> Hello,
>
> Is there an LCD to VGA ready-made circuits out there?
> (basically FPGA+RAM)
>
> I was able to generate VGA 640x480 timing using an
> LPC2478. This greatly slowed down the system, due to the
> high load on SDRAM.
> Now, to go to higher resolutions, it is not much of an
> option on LPC2478. I have seen a VGA frame generator chip
> before that have built in frame buffer and then you can
> use LPC248 to clock 1024x768 at low frequency to the chip
> and then the chip will take care of generating the high
> speed XVGA timings. It found only one company but I was
> not able to get any communication back from them!
>
> IS there someone that offers a circuit (FPGA/RAM) to take
> in the LCD signals at low clock rate (4Mhz maybe) and
> then this circuit will buffer the data on RAM then take
> the same data and generate the required timings?
>
> My understanding is that this can be easily done using
> FPGA but I know thing about FPGA!

LPC2478 can do 1024x768, it should not "greatly slow down the system" as
it's all hardware ... Herbert Demmel on this list has done it.
Solomon do a wide range of standalone LCD controller chips if you want
something standalone but then you have an added problem of transferring
the graphics data into the controller chip. At least on the LPC2478 the
graphics buffer is part of the system ram.

You don't say what you are trying to display on the LCD?

--
Tim Mitchell

Hi,

> Is there an LCD to VGA ready-made circuits out there? (basically
> FPGA+RAM)
>
> I was able to generate VGA 640x480 timing using an LPC2478. This greatly
> slowed down the system, due to the high load on SDRAM.
> Now, to go to higher resolutions, it is not much of an option on
> LPC2478. I have seen a VGA frame generator chip before that have built
> in frame buffer and then you can use LPC248 to clock 1024x768 at low
> frequency to the chip and then the chip will take care of generating the
> high speed XVGA timings. It found only one company but I was not able to
> get any communication back from them!
>
> IS there someone that offers a circuit (FPGA/RAM) to take in the LCD
> signals at low clock rate (4Mhz maybe) and then this circuit will buffer
> the data on RAM then take the same data and generate the required
> timings?
>
> My understanding is that this can be easily done using FPGA but I know
> thing about FPGA!

Why not use an OMAP or iMX51, these support HDMI... It's a step up, I
would grant you. ;-)

-- Paul.

--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks V2 is out for LPC1700, LPC3100, LPC3200, SAM9, and more!

An Engineer's Guide to the LPC2100 Series