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Linux/am3352: TSC unexpected touch up event

LIANG WANG102707
Expert 1415 points

Part Number: AM3352
Other Parts Discussed in Thread: AM3352

Tool/software: Linux

Hello:

We are using linux 4.4.41  with 5 wires touch screen to am3352 touch controller.

When we drag in the ts test ,we found that it  sometimes  touch up ,but we do not touch up.

Is there someone meet this problem?

Is it related to the driver ?Or can it be fixed by change in the tslib?

Best regard

Wangl

  • 0
    TI__Guru 65405 points

    Hi Wangl,

    This problem is not observed on the EVM boards.

    Could you recalibrate the touchscreen and perform the same test again.

    If the problem still appears I suspect lower sensitivity of the touchscreen and if you drag on TSC with variable pressure and on some points the pressure is lower it decides touch up event appear. This is only an assumption.

    You can try an useful tool for TSC events logging as:

    # evtest /dev/input/touchscreen0

    You can make a single drag and attach the log in a text file.

    BR

    Tsvetolin Shulev

  • 0 in reply to Cvetolin Shulev-XID
    Expert 1415 points

    Hello Tsvetolin :

    We do find the touch up  event in the ts_test of ts_lib when we drag on the touch screen.

    The problem is how to make the  sensitivity of the touchscreen to higher?

    Can it be set  higher to filter the unwanted touch up?

    Best regard

    wangl

  • 0 in reply to LIANG WANG102707
    TI__Guru 65405 points
    I have missed to ask you what touchscreen you are using and how it is configured in the device tree and kernel config?
    It is important for further investigation to search in documentation of touchscreen for threshold for minimal pressure.

    BR
    Tsvetolin Shulev