Issues with udoo 7'' LCD panels

Hi,

We recently ordered one and then 4 udoo quad with 7'' LCD panels. The udoo boards are just working well and perfect for our project but we have many issues with the LCD 7'' panels !

Touch issues
On the 5 panels we ordered only one is behaving correctly ! The other five have "dead" touch zones.
The first one we ordered has an horizontal strip of about 100 pixels which is completely unresponsive. The other 3 which do not work as expected have a vertical strip of about 60 pixels on the left border which is also not responsive.

I did the check with Ubuntu and Android reference images and a self-compiled test program. The result is always the same, some regions of the screen do not detect the touch. I recompiled the driver with debug output in the interrupt service routine of the touch controller and noticed that no interrupt is generated for the the touch events in the aforementioned zone. This is then typically an hardware problem since the same software works well and detects all touch events with one of the five screens.

Do other udooers have similar issues ? Is it a manufacturing problem or just me being unlucky ?

Heating issues
Some other members reported that their screens were abnormally heating. I experience the same and would appreciate any hint on how to fix this.
See this post and following ones.

 

Hi delba,

Thanks for the quick feedback.

I first thought that the left side vertical zone on the left could be due to some "reserved area" for Android buttons or something in this style and then checked in the driver and could not see anything in this sense (all defines are commented out).

Unlucky batch of hardware then... 4 screens out of 5. This is more than suspect.

Code:

sitronix_i2c_touch.h

//#define SITRONIX_SENSOR_KEY
//#define SITRONIX_TOUCH_KEY
//#define SITRONIX_KEY_BOUNDARY_MANUAL_SPECIFY

And since the exact same software works with one of the screens without problem (the whole touch area is responsive) we can exclude some wrong conversions, incorrect interpretation of the data,... The point is that there is absolutely no interrupt when touched in this zone.

From this point I can only see few possible reasons:
1) crappy hardware
2) missing some initialisation in the driver but I could not find anything in this sense in the Sitronix protocol definition (see here).
3) missed interrupts (but why would we miss interrupt only in some fixed area ?)
4) buggy firmware in the Sitronix touch controller

Regarding the heating issues I did some measurements and got temperatures of more than 50°C at the screen surface and almost 80°C on the U2 chip at the back just above the connector. This matches what is described in the other forum thread.

Some measurements:
Front


Back

 

Hi Romain
I have the same problems.
Heating issue and deat zone on the top of the touch screen. :-(

Hill

 

Hi Hill,

Sad that you experience the same issues but in a sense it's good to see that other users and people at udoo themselves have similar issues.
For me it's clear that there is a serious problem with these screens or at least with a whole lot of them.

Let's wait and see what udoo people say about these issues.
We already have 2 RMA tickets open for our screens. I can only advise you to open one as well. Just go there to open a new ticket.

Cheers

 

Hi,

Any update on both of this issues ?

1) Unresponsive touch area
Did you perform further tests ? What's the outcome of your investigations ?

2) Heating
I think that assumptions made by in this post are good starting points. Did you investigate further ? If the problem is with the step-down converter IC can you propose a pin-compatible alternative ? We could patch our adapter board if necessary.

 

I too have the problem with the left vertical dead zone...

 

Hi Fabio,

I got my defective screens replaced. Open a ticket here and ask for a RMA (Return Merchandise Authorization).

You'll find details and conditions at this page: http://shop.udoo.org/eu/terms-and-conditions

Cheers,
Romain

 

Thank you very much! I will try it!