How to replace a 3.5" LCD by a 7" on Mini2440?

Joao Ferreira
Hello All!

Sorry about my ignorance, but Im a newbie. I have one Mini2440 with W35
3.5" original LCD which works just fine. I bought a new S70 7" thinking
that would be just plugging the new and it will work fine, but it is not. 

The 7" gets all white with two thick grey bars in the middle after some
line movements at boot. 

There is a drive, a configuration or something? Reading several threads
looks like is something complex. Replacing a 3.5" for a 7" is really so
difficult or there is some kind of tutorial somewhere?

Thank you in advance.

JR

Screwface
Hi Joao,

You'll have to add your screen characteristics in the BSP file
(mach-mini2440). This screen is not actually supported in the factory linux
kernel.

Joao Ferreira
Thank you for the reply Screwface! I think in the datasheet of the display
I have the characteristics. Where exactly I find this file in the Mini
2440?

davef
According to this the A70:

http://search.gmane.org/?query=a70&group=gmane.comp.embedded.ptxdist...

is in the Pengutronix BSP.  Maybe, that helps.

http://www.oselas.org/oselas/bsp/pengutronix/mini2440_bsp_en.html

Screwface
You're right Dave, A70 is in Pengutronix BSP, but I'm not sure timings are
the same than S70.

Joao, the file is in arch/arm/s3c2440 folder of your linux kernel.
But I won't be able to help you to calculate the values as I don't know how
they are calculated. I also tried to change the mini2440 screen for a
bigger one but I was stuck at that level, and I have no time at the moment
to spend on this topic. :(

davef
http://article.gmane.org/gmane.comp.embedded.ptxdist.oselas.community/17...

"The original Tiny6410 implementation
targets S70 screen which uses 1-wire but also has additional buttons
(I just remember the one for orientation)."

Do the mini2440 and mini6410 use the same LCD controller?

Screwface
I think so, but different clock speeds. So values are not the same.

Juergen Beisert
Mini2440 and Mini6410 share the same LCD connector. But due to the nature
of their different SoCs, the LCD controller inside the SoC differs. But at
the electrical level of the LCD signals this doesn't matter. You just need
to set up their controllers differently to output the same signals and
timings.

Joao Ferreira
Still no luck!

Im accessing the Mini2440 via Telnet. I found no arch/arm/ folder. Im not
a Linux user, so I looked everywhere and found nothing. 

Any other suggestions?

davef
arch/arm will be on your host computer, where you placed the kernel source
prior to cross-compiling.

Joao Ferreira
No, I just bought this Mini2440 with a 3.5" display which came working out
of the box with Qtopia. So I bought one 7" LCD display thinking that would
be just unplug the smaller and install the 7". But did not work at all. Im
unable to solve this problem even searching in the forums. So I bought a
new one, already with a 7" LCD, but unluckily came in separated boxes and
without compatible configuration too! Now I have two Mini 2440, two 7" LCD
display and both just works with the 3.5!

The name is FriendlyARM, but looks like it is not so friendly at all, since
for a simple task which should be exchange a display, looks like you have
to be a savvy user to compile a kernel! And Im not finding any solution
even looking in several forums.

Any thoughts?

Juergen Beisert
Embedded devices are not like desktop PCs. Your expectation is wrong. Your
embedded toy isn't a multi giga herz giga byte machine. Its much smaller in
many ways and needs more love to make it work in a way you like it.

The software cannot detect the attached display (like a desktop PC can). So
its up to you to tell the software what you intend to connect.

Welcome to the world of embedded programming.

Joao Ferreira
Juergen,

I know that, but when you buy a system, like this new 7" Mini 2440, it
should come working just like my old 3.5" came. If someone just want to
start playing with FriendlyARM, getting started having to compile a kernel
for adjust the LCD timing should not be the first experience. And if even
in this forum looks like is not a easy task, what to say for a newbie? But
if this is my fault or from the vendor, is not the point. 

If someone could try any suggestion will be welcome.

Juergen Beisert
> If someone could try any suggestion will be welcome.

Keep your fingers on the software. If you intend to do serious things with
your new toys you must first create a reliable build environment. Otherwise
you will end up hunting phantoms when your own programs are crashing and
you will be *really* frustrated.

Reggie
We're also a random collection of people across the net who might or might
not have answers for you, the simple fact is that all of us at one point or
another have had to deal with our own newbie-ness and learn.

Joao Ferreira
Well, this is not meant to be a toy. I was thinking in using it to be a
touch interface with a pre loaded remote control QT application which sends
control strings over serial and controls my stuff. 

I bought the 3.5" which came working out of the box. The programmer just
uploaded the software via ftp to my unit and worked perfect. But I think
the 3.5 " LCD is too small for my eyes and fingers. So I bought one 7" LCD
which did not work, and after search everywhere, I was not able even to
find a meaningful tutorial for this supposed simple exchange. Im too busy
dealing with other problems and I thought this forum could be of some help.
But looks like  everyone have to learn by themselves. Eventually, I one
masters in this stuff, he come back here make fun of who does not. 

I contact at least 5 people who have this ARMs and nobody knows how to deal
with this display stuff. If who use cant, what to say form a ex newbie.

I will ebay this UNFriendlyARMs and replace by PC based tablet which I can
deal myself without bothering the "experts". 

Thank you very much.

Ozzy
Hey,

I think there is a simple solution: just set up your system like described
here:
http://mini2440vietnam.blogspot.de/2011/01/install-linux-into-mini2440-b...

The only thing you have to change is not to use the "zImage_T35" but the
A70 image from the CD or from the friendly-arm download. 

I tried this manual and got the same display results as you did, and after
some searching I found the hint with the wrong display-image. After that
everything worked fine.

Best regards
Ozzy

Reggie
I get a little tired of people demanding that we help them and then
complaining when we do, there is of course the company that the product was
purchased from if all else fails but that seems not to be an option these
days.

If you can't do the simple things, like compile a kernel with the correct
driver or read various tutorials on the net on how friendlyarm boards work,
then you're not going to get very far anyway.

The lcd's used to be controlled by a commandline option called mini2440=,
and also selecting the correct lcd in the menuconfig.

Drivers > Graphics Support >  Support for frame buffer devices > LCD
Select.

From there you can actually select the lcd you want, they're all in there.

well
Sorry to bring up this discussion. at first i also get this problem.
but after some checking, the zImage for 7 inch LCD is included on the
shipped DVD.
or you can download it at http://www.arm9.net/download.asp
i already tried it, and it works like a charm

Well