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LCD touch screen unusable on Overo/Chestnut

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JamesAng

Re: LCD touch screen unusable on Overo/Chestnut

Ash Charles-2 wrote

Hi James,
For my suggestion to change the version of Xorg, you should just be
able to opkg a different version. Here is some documentation on the
opkg command: http://gumstix.org/add-software-packages.html.

Hi Ash,

I tried using opkg to update the Xorg in Gumstix but the "opkg list_installed" and "opkg list" has both the same version of xserver-xorg - 2:1.9.4-r19.0.9

Search Angstrom-Distribution Package Feed at
http://www.angstrom-distribution.org/repo/
shows only 1.3.0.0-r4

So, what are the commands that I need to execute in Gumstix to change the installed Xorg and from which source?

Thks in adv.

James.

BrentP

Re: LCD touch screen unusable on Overo/Chestnut

In reply to this post by JamesAng

James:

I didn't actually get as far as modifying the driver just yet. I had to put my Gumstix project on the back burner soon after posting this, but I should be getting back to it soon.

I can dig up some more details in a bit, but basically, I believe I set "defaultdisplay=dvi" in U-Boot which then uses the generic LCD driver. I then used a combination of "fbset" and echo'ing timings to "/sys/devices/omapdss/display0/timings"

According to my notes I did:

echo "15000,480/1/15/14,272/1/45/33" > /sys/devices/omapdss/display0/timings

I'd have to go back and try that again to make sure that's exactly what did it, but that was the path I was on.

I'll try to post something more detailed later, but maybe this can get you going in the right direction. Ultimately, we need to patch the driver as a workaround until the hardware issue is solved.

Brent

JamesAng wrote

BrentP wrote

I confirmed yesterday that my touchscreen responsiveness was directly related to the pixel clock setting of the LCD. I still don't understand why, but if I set the pixel clock to 9.6MHz (the nominal clock in the datasheet of the LCD), the touchscreen response was sluggish. As I increased it, it became better and better. I currently have it set to 15Mhz which is the top end spec'd in the datasheet. I had it as higha s 23.5MHz and everything was still working well.

Any clues as to why the pixel clock on the LCD would effect things like this?

Brent

Hi Brent,

I'm also experiencing the same sluggish of the touchscreen on my Chestnut and LG LCD screen.

Can you share with the community the exact steps to change the frequency of the pixel clock and how to have bitbake uses the modified file when compiling.

Many Thanks in adv.

James.

JamesAng

Re: LCD touch screen unusable on Overo/Chestnut

BrentP wrote

James:

I didn't actually get as far as modifying the driver just yet. I had to put my Gumstix project on the back burner soon after posting this, but I should be getting back to it soon.

I can dig up some more details in a bit, but basically, I believe I set "defaultdisplay=dvi" in U-Boot which then uses the generic LCD driver. I then used a combination of "fbset" and echo'ing timings to "/sys/devices/omapdss/display0/timings"

According to my notes I did:

echo "15000,480/1/15/14,272/1/45/33" > /sys/devices/omapdss/display0/timings

I'd have to go back and try that again to make sure that's exactly what did it, but that was the path I was on.

I'll try to post something more detailed later, but maybe this can get you going in the right direction. Ultimately, we need to patch the driver as a workaround until the hardware issue is solved.

Brent

Hi Brent,

Understood. :)
But your investigation into the timing issue do help to narrow the search for a permanent solution.

I look forward to more details that you can provide so that I can also try to solve it at my end over here.

Cheers~!

James.

dcraw101

Re: LCD touch screen unusable on Overo/Chestnut

JamesAng wrote

BrentP wrote

James:

I didn't actually get as far as modifying the driver just yet. I had to put my Gumstix project on the back burner soon after posting this, but I should be getting back to it soon.

I can dig up some more details in a bit, but basically, I believe I set "defaultdisplay=dvi" in U-Boot which then uses the generic LCD driver. I then used a combination of "fbset" and echo'ing timings to "/sys/devices/omapdss/display0/timings"

According to my notes I did:

echo "15000,480/1/15/14,272/1/45/33" > /sys/devices/omapdss/display0/timings

I'd have to go back and try that again to make sure that's exactly what did it, but that was the path I was on.

I'll try to post something more detailed later, but maybe this can get you going in the right direction. Ultimately, we need to patch the driver as a workaround until the hardware issue is solved.

Brent

Hi Brent,

Understood. :)
But your investigation into the timing issue do help to narrow the search for a permanent solution.

I look forward to more details that you can provide so that I can also try to solve it at my end over here.

Cheers~!

James.

I am trying to connect the Chestnut to a an AUO 5.7" LCD. If I set the pixel clock to 25 MHz (as per the AUO datasheet) then the touch panel is very erratic and updates very slowly. if I change the pixel clock down to 10MHz then the touch panel is much more responsive, but now my LCD is refreshing too slow. Could this be an electical interferrence or cross-talk issue? Could it help to lower the speed of the SPI bus communicating with the ADS7846?

thanks,
Doug

JamesAng

Re: LCD touch screen unusable on Overo/Chestnut

Hi Doug,

dcraw101 wrote:

>
>
>
> JamesAng wrote:
>>
>>
>> BrentP wrote:
>>>
>>> James:
>>>
>>> I didn't actually get as far as modifying the driver just yet. I had to
>>> put my Gumstix project on the back burner soon after posting this, but I
>>> should be getting back to it soon.
>>>
>>> I can dig up some more details in a bit, but basically, I believe I set
>>> "defaultdisplay=dvi" in U-Boot which then uses the generic LCD driver.
>>> I then used a combination of "fbset" and echo'ing timings to
>>> "/sys/devices/omapdss/display0/timings"
>>>
>>> According to my notes I did:
>>>
>>> echo "15000,480/1/15/14,272/1/45/33" >
>>> /sys/devices/omapdss/display0/timings
>>>
>>> I'd have to go back and try that again to make sure that's exactly what
>>> did it, but that was the path I was on.
>>>
>>> I'll try to post something more detailed later, but maybe this can get
>>> you going in the right direction. Ultimately, we need to patch the
>>> driver as a workaround until the hardware issue is solved.
>>>
>>>
>>> Brent
>>>
>>
>> Hi Brent,
>>
>> Understood. :)
>> But your investigation into the timing issue do help to narrow the search
>> for a permanent solution.
>>
>> I look forward to more details that you can provide so that I can also
>> try to solve it at my end over here.
>>
>> Cheers~!
>>
>> James.
>>
>>
>
> I am trying to connect the Chestnut to a an AUO 5.7" LCD. If I set the
> pixel clock to 25 MHz (as per the AUO datasheet) then the touch panel is
> very erratic and updates very slowly. if I change the pixel clock down to
> 10MHz then the touch panel is much more responsive, but now my LCD is
> refreshing too slow. Could this be an electical interferrence or
> cross-talk issue? Could it help to lower the speed of the SPI bus
> communicating with the ADS7846?
>
> thanks,
> Doug
>

ATM, I've put this at a lower priority.
Have you tried to see if the response between "ts_test"'s draw and that on
the GUI is vastly different?

For mine without any modification, ts_test give a good response time but
sluggish when on the GUI..
But why??..
--
View this message in context: http://old.nabble.com/LCD-touch-screen-unusable-on-Overo-Chestnut-tp30728009p32503706.html
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Stephen Farnsworth-2

Re: LCD touch screen unusable on Overo/Chestnut

Took me awhile to find this thread, but I am having a related problem with 2 recently purchased lcd + chestnut43, although it is worse than just slow sampling time. Mine almost never work. Switching display to DVI causes the touchscreen to actually work. Where is this separate thread for the LG device driver? I'd love to help get something upstream to fix this.

On Tue, Sep 20, 2011 at 7:17 PM, JamesAng <[hidden email]> wrote:

Hi Doug,

dcraw101 wrote:
>
>
>
> JamesAng wrote:
>>
>>
>> BrentP wrote:
>>>
>>> James:
>>>
>>> I didn't actually get as far as modifying the driver just yet. I had to
>>> put my Gumstix project on the back burner soon after posting this, but I
>>> should be getting back to it soon.
>>>
>>> I can dig up some more details in a bit, but basically, I believe I set
>>> "defaultdisplay=dvi" in U-Boot which then uses the generic LCD driver.
>>> I then used a combination of "fbset" and echo'ing timings to
>>> "/sys/devices/omapdss/display0/timings"
>>>
>>> According to my notes I did:
>>>
>>> echo "15000,480/1/15/14,272/1/45/33" >
>>> /sys/devices/omapdss/display0/timings
>>>
>>> I'd have to go back and try that again to make sure that's exactly what
>>> did it, but that was the path I was on.
>>>
>>> I'll try to post something more detailed later, but maybe this can get
>>> you going in the right direction. Ultimately, we need to patch the
>>> driver as a workaround until the hardware issue is solved.
>>>
>>>
>>> Brent
>>>
>>
>> Hi Brent,
>>
>> Understood. :)
>> But your investigation into the timing issue do help to narrow the search
>> for a permanent solution.
>>
>> I look forward to more details that you can provide so that I can also
>> try to solve it at my end over here.
>>
>> Cheers~!
>>
>> James.
>>
>>
>
> I am trying to connect the Chestnut to a an AUO 5.7" LCD. If I set the
> pixel clock to 25 MHz (as per the AUO datasheet) then the touch panel is
> very erratic and updates very slowly. if I change the pixel clock down to
> 10MHz then the touch panel is much more responsive, but now my LCD is
> refreshing too slow. Could this be an electical interferrence or
> cross-talk issue? Could it help to lower the speed of the SPI bus
> communicating with the ADS7846?
>
> thanks,
> Doug
>

ATM, I've put this at a lower priority.
Have you tried to see if the response between "ts_test"'s draw and that on
the GUI is vastly different?

For mine without any modification, ts_test give a good response time but
sluggish when on the GUI..
But why??..
--
View this message in context: http://old.nabble.com/LCD-touch-screen-unusable-on-Overo-Chestnut-tp30728009p32503706.html

Sent from the Gumstix mailing list archive at Nabble.com.

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definitive record of customers, application performance, security
threats, fraudulent activity and more. Splunk takes this data and makes
sense of it. Business sense. IT sense. Common sense.
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kaoruko

Re: LCD touch screen unusable on Overo/Chestnut

Stephen,

Did you make progress with this? Which revision of the chestnut43 are you using? (I've two R3078s with this problem and an R2467 without).
The screens did not work at all with the stable angstrom images (omap3-desktop), and I had to use the latest experimental image.

The touchscreen is still sluggish - I've found the frequency hack to work but am looking for an upstream fix.

Christian Ruocco

Re: LCD touch screen unusable on Overo/Chestnut

In reply to this post by Derek Baum

I have this issue with all 10 of our Overo/Chestnut combos.. Erratic
touchscreen behavior and it also seems you have to press really hard on the
screen to get consistent samples, and then they're still not very
consistent. When I say really hard I mean substantially more than the light
brush needed to use an iPhone or the Verdex/ConsoleLCD16-vx for an example.
I have even put some debugging code in the driver to determine how reliably
the PENIRQ fires, and it is inconsistent, so I'm assuming this is a hardware
issue? There have been suggestions that it's somehow tied to the LCD refresh
rate. I have experimented with that and found that there is no correlation
for me at least. I have also used the prebuilt images on Gumstix site to
double check I haven't mangled something. I used the SD image from
http://cumulus.gumstix.org/images/angstrom/factory/2011-08-30-1058/ and
using X-Windows on that exhibits the same problem.

Any suggestions are welcome!

Kind Regards,
Christian Ruocco

Mark Zieg

Re: LCD touch screen unusable on Overo/Chestnut

Hi Christian,

Are the screens LG or Samsung? We experienced exactly what you describe with LG, but the Samsung ones worked much better.

Try adding the InvertY option to your /usr/lib/X11/xorg.conf.d/05-evdev.conf:

Section "InputClass"
Identifier "evdev touchscreen catchall"
MatchIsTouchscreen "on"
MatchDevicePath "/dev/input/event*"
Driver "evdev"
Option "InvertY" "true"
EndSection

Calibrate your screen using a script like this (get ts_calibrate from 'apt-get install tslib')

$ cat scripts/calibrateScreen.sh
#!/bin/bash
EVENT=`ls /dev/input/ | grep event`
sudo TSLIB_TSDEVICE=/dev/input/$EVENT /usr/bin/ts_calibrate

(I assume you've already done the "setenv defaultdisplay lcd43" bit.)

Also, occasionally we find that the screens don't want to act as input devices following a boot, so we bounce the driver using a script like this:

$ cat scripts/bounceTouch.sh
#!/bin/bash
sudo modprobe -r ads7846
sleep 1
sudo modprobe ads7846

We've been reasonably happy with the screens after following these steps. Not thrilled, but they get the job done.

-MZ

-----Original Message-----
From: Christian Ruocco [mailto:[hidden email]]
Sent: Tuesday, March 06, 2012 3:01 AM
To: [hidden email]
Subject: Re: [Gumstix-users] LCD touch screen unusable on Overo/Chestnut

I have this issue with all 10 of our Overo/Chestnut combos.. Erratic touchscreen behavior and it also seems you have to press really hard on the screen to get consistent samples, and then they're still not very consistent. When I say really hard I mean substantially more than the light brush needed to use an iPhone or the Verdex/ConsoleLCD16-vx for an example.
I have even put some debugging code in the driver to determine how reliably the PENIRQ fires, and it is inconsistent, so I'm assuming this is a hardware issue? There have been suggestions that it's somehow tied to the LCD refresh rate. I have experimented with that and found that there is no correlation for me at least. I have also used the prebuilt images on Gumstix site to double check I haven't mangled something. I used the SD image from http://cumulus.gumstix.org/images/angstrom/factory/2011-08-30-1058/ and using X-Windows on that exhibits the same problem.

Any suggestions are welcome!

Kind Regards,
Christian Ruocco

--
View this message in context: http://gumstix.8.n6.nabble.com/LCD-touch-screen-unusable-on-Overo-Chestnut-tp561488p4550477.html
Sent from the Gumstix mailing list archive at Nabble.com.

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error please notify the sender immediately and then delete this e-mail.
E-mail transmission cannot be guaranteed to be secure or error free as
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Stephen Farnsworth-2

Re: LCD touch screen unusable on Overo/Chestnut

It is the LG screens. There is a bad board design and there seems to be around +-1V high frequency noise at the touch device controller on the chestnut boards according to my o-scope. I've given up for now, and am now banging my head on other gumstix things...

On Tue, Mar 6, 2012 at 5:04 AM, Mark Zieg <[hidden email]> wrote:

Hi Christian,

Are the screens LG or Samsung? We experienced exactly what you describe with LG, but the Samsung ones worked much better.

Try adding the InvertY option to your /usr/lib/X11/xorg.conf.d/05-evdev.conf:

Section "InputClass"
Identifier "evdev touchscreen catchall"
MatchIsTouchscreen "on"
MatchDevicePath "/dev/input/event*"
Driver "evdev"
Option "InvertY" "true"
EndSection

Calibrate your screen using a script like this (get ts_calibrate from 'apt-get install tslib')

$ cat scripts/calibrateScreen.sh
#!/bin/bash
EVENT=`ls /dev/input/ | grep event`
sudo TSLIB_TSDEVICE=/dev/input/$EVENT /usr/bin/ts_calibrate

(I assume you've already done the "setenv defaultdisplay lcd43" bit.)

Also, occasionally we find that the screens don't want to act as input devices following a boot, so we bounce the driver using a script like this:

$ cat scripts/bounceTouch.sh
#!/bin/bash
sudo modprobe -r ads7846
sleep 1
sudo modprobe ads7846

We've been reasonably happy with the screens after following these steps. Not thrilled, but they get the job done.

-MZ

-----Original Message-----
From: Christian Ruocco [mailto:[hidden email]]
Sent: Tuesday, March 06, 2012 3:01 AM
To: [hidden email]
Subject: Re: [Gumstix-users] LCD touch screen unusable on Overo/Chestnut

I have this issue with all 10 of our Overo/Chestnut combos.. Erratic touchscreen behavior and it also seems you have to press really hard on the screen to get consistent samples, and then they're still not very consistent. When I say really hard I mean substantially more than the light brush needed to use an iPhone or the Verdex/ConsoleLCD16-vx for an example.
I have even put some debugging code in the driver to determine how reliably the PENIRQ fires, and it is inconsistent, so I'm assuming this is a hardware issue? There have been suggestions that it's somehow tied to the LCD refresh rate. I have experimented with that and found that there is no correlation for me at least. I have also used the prebuilt images on Gumstix site to double check I haven't mangled something. I used the SD image from http://cumulus.gumstix.org/images/angstrom/factory/2011-08-30-1058/ and using X-Windows on that exhibits the same problem.

Any suggestions are welcome!

Kind Regards,
Christian Ruocco

--
View this message in context: http://gumstix.8.n6.nabble.com/LCD-touch-screen-unusable-on-Overo-Chestnut-tp561488p4550477.html
Sent from the Gumstix mailing list archive at Nabble.com.

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material. If you are not the addressee, any disclosure, reproduction,
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error please notify the sender immediately and then delete this e-mail.
E-mail transmission cannot be guaranteed to be secure or error free as
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Christian Ruocco

Re: LCD touch screen unusable on Overo/Chestnut

In reply to this post by Mark Zieg

Hi Mark,

Thanks so much for your reply!

Just to clarify, you say "We've been reasonably happy with the screens after following these steps. Not thrilled, but they get the job done. ". Are you talking about the LG screens here or the Samsung?

If you mean the LG, would you say the Samsung's are working as well as you would expect for a good user experience (ie. iphone or even verdex/touchscreen combo quality) or is just better than with the LG, but still not great?

Kind Regards,
Christian

Christian Ruocco

Re: LCD touch screen unusable on Overo/Chestnut

In reply to this post by Stephen Farnsworth-2

Hi Stephen,

Thanks for your reply! I was pretty sure it was hardware. Have you tried the Samsung screen yet?

Kind Regards,
Christian

Mark Zieg

Re: LCD touch screen unusable on Overo/Chestnut

In reply to this post by Christian Ruocco

We've been reasonably happy with Samsung, but you're never going to get iPhone quality for $50.

The LG units we use as coasters.

Mark

On Mar 8, 2012, at 5:23 AM, "Christian Ruocco" <[hidden email]> wrote:

> Hi Mark,
>
> Thanks so much for your reply!
>
> Just to clarify, you say "We've been reasonably happy with the screens after
> following these steps. Not thrilled, but they get the job done. ". Are
> you talking about the LG screens here or the Samsung?
>
> If you mean the LG, would you say the Samsung's are working as well as you
> would expect for a good user experience (ie. iphone or even
> verdex/touchscreen combo quality) or is just better than with the LG, but
> still not great?
>
> Kind Regards,
> Christian
>
>
>
> --
> View this message in context: http://gumstix.8.n6.nabble.com/LCD-touch-screen-unusable-on-Overo-Chestnut-tp561488p4557890.html
> Sent from the Gumstix mailing list archive at Nabble.com.
>
> ------------------------------------------------------------------------------
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> also focuses on allowing computing to be delivered as a service.
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material. If you are not the addressee, any disclosure, reproduction,
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strictly prohibited. If you have received this transmission in
error please notify the sender immediately and then delete this e-mail.
E-mail transmission cannot be guaranteed to be secure or error free as
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Stephen Farnsworth-2

Re: LCD touch screen unusable on Overo/Chestnut

I haven't tried the Samsung screen. It is low on my priorities to get a touchscreen working. At some point in the future I may try hacking the hardware just to see if I can reduce noise enough to get the LG touchscreen to work.

On Thu, Mar 8, 2012 at 3:59 AM, Mark Zieg <[hidden email]> wrote:

We've been reasonably happy with Samsung, but you're never going to get iPhone quality for $50.

The LG units we use as coasters.

Mark

On Mar 8, 2012, at 5:23 AM, "Christian Ruocco" <[hidden email]> wrote:

> Hi Mark,
>
> Thanks so much for your reply!
>
> Just to clarify, you say "We've been reasonably happy with the screens after
> following these steps. Not thrilled, but they get the job done. ". Are
> you talking about the LG screens here or the Samsung?
>
> If you mean the LG, would you say the Samsung's are working as well as you
> would expect for a good user experience (ie. iphone or even
> verdex/touchscreen combo quality) or is just better than with the LG, but
> still not great?
>
> Kind Regards,
> Christian
>
>
>
> --
> View this message in context: http://gumstix.8.n6.nabble.com/LCD-touch-screen-unusable-on-Overo-Chestnut-tp561488p4557890.html
> Sent from the Gumstix mailing list archive at Nabble.com.
>
> ------------------------------------------------------------------------------
> Virtualization & Cloud Management Using Capacity Planning
> Cloud computing makes use of virtualization - but cloud computing
> also focuses on allowing computing to be delivered as a service.
> http://www.accelacomm.com/jaw/sfnl/114/51521223/
> _______________________________________________
> gumstix-users mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/gumstix-users

********************************************************

The information transmitted is intended only for the person or entity to
which it is addressed and may contain confidential and/or privileged
material. If you are not the addressee, any disclosure, reproduction,
copying, distribution, or other dissemination or use of this communication is
strictly prohibited. If you have received this transmission in
error please notify the sender immediately and then delete this e-mail.
E-mail transmission cannot be guaranteed to be secure or error free as
information could be intercepted, corrupted lost, destroyed, arrive late or
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JamesAng

Re: LCD touch screen unusable on Overo/Chestnut

In reply to this post by Stephen Farnsworth-2

Hi,

On Wed, Mar 7, 2012 at 2:33 AM, Stephen Farnsworth <[hidden email]> wrote:
> It is the LG screens. There is a bad board design and there seems to be
> around +-1V high frequency noise at the touch device controller on the
> chestnut boards according to my o-scope. I've given up for now, and am now
> banging my head on other gumstix things...
>

Can you point out the test points where you observed the noise?

I would like to see for myself too since I too have the same issue
with my Chestnut+LG setup.

--
Regards,
James

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Stephen Farnsworth-2

Re: LCD touch screen unusable on Overo/Chestnut

I'll have to pull it out and take a look again. I believe it was the power rail for the touch driver. I tried to take a screenshot on the oscope, but couldn't do it quickly so I gave up.

On Thu, Mar 8, 2012 at 4:49 PM, James <[hidden email]> wrote:

Hi,

On Wed, Mar 7, 2012 at 2:33 AM, Stephen Farnsworth <[hidden email]> wrote:
> It is the LG screens. There is a bad board design and there seems to be
> around +-1V high frequency noise at the touch device controller on the
> chestnut boards according to my o-scope. I've given up for now, and am now
> banging my head on other gumstix things...
>

Can you point out the test points where you observed the noise?

I would like to see for myself too since I too have the same issue
with my Chestnut+LG setup.

--
Regards,
James

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Neil MacMunn

Re: LCD touch screen unusable on Overo/Chestnut

Hi Everyone,

There is a known issue with the Chestnut43 that could be causing
touchscreen problems. See here:

http://gumstix.org/hardware-design/product-changes-known-issues-a-eol/67-known-issues/203-pki-2012-1-chestnut43-r3078-issues-r1-not-populated.html

-
Neil

On Thu, Mar 8, 2012 at 5:39 PM, Stephen Farnsworth <[hidden email]> wrote:

> I'll have to pull it out and take a look again. I believe it was the power
> rail for the touch driver. I tried to take a screenshot on the oscope, but
> couldn't do it quickly so I gave up.
>
>
> On Thu, Mar 8, 2012 at 4:49 PM, James <[hidden email]> wrote:
>>
>> Hi,
>>
>> On Wed, Mar 7, 2012 at 2:33 AM, Stephen Farnsworth <[hidden email]>
>> wrote:
>> > It is the LG screens. There is a bad board design and there seems to be
>> > around +-1V high frequency noise at the touch device controller on the
>> > chestnut boards according to my o-scope. I've given up for now, and am
>> > now
>> > banging my head on other gumstix things...
>> >
>>
>> Can you point out the test points where you observed the noise?
>>
>> I would like to see for myself too since I too have the same issue
>> with my Chestnut+LG setup.
>>
>> --
>> Regards,
>> James
>>
>>
>> ------------------------------------------------------------------------------
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>
>
>
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Mark Zieg

Re: LCD touch screen unusable on Overo/Chestnut

Hi Neil,

Do we know which problem(s) this missing resistor would cause? Would this cause jitter, or miscalibration, or coordinate inversion, or visible flicker when USB / ethernet devices are plugged in, or periodic failure to respond to inputs following reboot, or color palette changes, or...? (I've experienced 6 of those 7, and am just wondering how delighted I should be with this discovery ;-)

Thanks,

Mark Zieg

On Mar 9, 2012, at 2:42 PM, Neil MacMunn wrote:

> Hi Everyone,
>
> There is a known issue with the Chestnut43 that could be causing
> touchscreen problems. See here:
>
> http://gumstix.org/hardware-design/product-changes-known-issues-a-eol/67-known-issues/203-pki-2012-1-chestnut43-r3078-issues-r1-not-populated.html
>
> -
> Neil
>
>
> On Thu, Mar 8, 2012 at 5:39 PM, Stephen Farnsworth <[hidden email]> wrote:
>> I'll have to pull it out and take a look again. I believe it was the power
>> rail for the touch driver. I tried to take a screenshot on the oscope, but
>> couldn't do it quickly so I gave up.
>>
>>
>> On Thu, Mar 8, 2012 at 4:49 PM, James <[hidden email]> wrote:
>>>
>>> Hi,
>>>
>>> On Wed, Mar 7, 2012 at 2:33 AM, Stephen Farnsworth <[hidden email]>
>>> wrote:
>>>> It is the LG screens. There is a bad board design and there seems to be
>>>> around +-1V high frequency noise at the touch device controller on the
>>>> chestnut boards according to my o-scope. I've given up for now, and am
>>>> now
>>>> banging my head on other gumstix things...
>>>>
>>>
>>> Can you point out the test points where you observed the noise?
>>>
>>> I would like to see for myself too since I too have the same issue
>>> with my Chestnut+LG setup.
>>>
>>> --
>>> Regards,
>>> James
>>>
>>>
>>> ------------------------------------------------------------------------------
>>> Virtualization & Cloud Management Using Capacity Planning
>>> Cloud computing makes use of virtualization - but cloud computing
>>> also focuses on allowing computing to be delivered as a service.
>>> http://www.accelacomm.com/jaw/sfnl/114/51521223/
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>>> gumstix-users mailing list
>>> [hidden email]
>>> https://lists.sourceforge.net/lists/listinfo/gumstix-users
>>
>>
>>
>> ------------------------------------------------------------------------------
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>
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Neil MacMunn

Re: LCD touch screen unusable on Overo/Chestnut

On Fri, Mar 9, 2012 at 12:02 PM, Mark Zieg <[hidden email]> wrote:
> Hi Neil,
>
> Do we know which problem(s) this missing resistor would cause?

I've seen this manifest in a few ways, most notably, undetected
ADS7846 on cold boot. Coordinate inversion seems unlikely (I remember
this being a software issue a while back) but I've only tested a few
units.

-
Neil

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Stephen Farnsworth-2

Re: LCD touch screen unusable on Overo/Chestnut

I can verify that I am missing that resistor,
WO 28198 11-02
BRD30005-R3078

On Fri, Mar 9, 2012 at 12:21 PM, Neil MacMunn <[hidden email]> wrote:

On Fri, Mar 9, 2012 at 12:02 PM, Mark Zieg <[hidden email]> wrote:
> Hi Neil,
>
> Do we know which problem(s) this missing resistor would cause?

I've seen this manifest in a few ways, most notably, undetected
ADS7846 on cold boot. Coordinate inversion seems unlikely (I remember
this being a software issue a while back) but I've only tested a few
units.

-
Neil

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