Touchscreen and audio stop working after a long click on the screen

I have a Colibri T20 running on WEC7 with the image 1.4 and a resistive touchscreen. Sometimes when I keep pressed the touchscreen (long click) it stops working and also does the audio.
In this situation the application and the operating system keep working fine. I can click the screen controls with a mouse.

When I migrated from image 1.3 to 1.4, Toradex sent me a registry patch to avoid a ‘pop’ noise after I played an audio stream, that I’m currently using:


Dear @mllona

Unfortunately I was not able to reproduce the issue. I used

  • Colibri Evaluation Board V3.2
    • Colibri T20 512MB IT V1.2A
      • WEC7 V1.4
        • Added the two registry entries described in your question
        • (everything else in factory default configuration)
  • ET070080DH6 resistive touch display

I pressed the touch and released it after roughly 1-5 seconds, and repeated this several hundred times.
A few times I also tried much longer presses, doubleClick-and-hold, drag-and-hold, but I couldn’t render the touch non-functional.
Can you give me some more details about how to force the error?

I would also like to ask you for an additional test:
Please update the system to WEC7 V2.2. Does the problem still exist?

Regards, Andy

Dear Andy, thanks for your answer. Like I said, the failure occurs only sometimes. It’s not easy to reproduce.
I will try with WEC7 V2.2.

I’ve found the following link in the forum:
Colibri T20 touch screen freezes after 10 Hours usage in Version 1.4
Could this be related to that issue?

Dear @mllona

What we finally discussed in the other forum post was the fact, that de-initializing the ADC could disable the touch, too. This is, because these two functions share the same hardware.
Unless the long-touch triggers any ADC operations in your application, I can’t see a relation.

I have a few moe questions about when the touch starts failing. I hope they help us and also yourself to find the best way of triggering the problem.
Please note that audio, touch and ADC are all handled by the WM9715 chip. So we should look for any special events of these three features.

  1. Does the error happen already on the WinCe desktop, or only when your application is running? In the latter case, do you have any idea what in the error case might be special in terms of audio, ADC or touch?
  2. The system does power-down some analog circuits in two steps: by default 500ms and 1000ms after the last activity (end of audio playback, touch press, …). Is it likely that the freeze occurs if your long press ends at the moment when a power-down would occur, or is the time of a long-press way off this time?
  3. How often do you approximately need to do a long touch, and how long do you approximately hold the touch to force the error? Is it reasonable to reproduce the problem manually, or will it be necessary to build a circuit which emulates long touch presses automatically?

Regards, Andy

I was not able to reproduce the problem on the WinCe desktop, but it happens only sometimes, so it’s difficult to get a conclusion or to give you an answer to these questions.
I’m on the way of trying with image V2.2
Regards, Martin

Dear @mllona
As we didn’t get any similar complaints so far, I assume the error happens only in your particular environment. Please understand that we need to find a way to reproduce the problem, in order to be able to analyze and fix it.
Please get back to me as soon as you have any findings.
Regards, Andy