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What is the interface to a touchscreen driver from Qt

John Carpenter
Prodigy 30 points
Other Parts Discussed in Thread: OMAP-L138

Hello,

I am in need of assistance.  I am working on a custom-built OMap-L138 board with an AD7843 Digitizer chip.  Further, I have a linux kernel (2.6) running on the ARM, and need to design a custom device driver for the touchscreen.  On our board, we interface to the touchscreen digitizer through our FPGA, which means that none of the pre-built drivers in "menuconfig" will work for the touchscreen.  I also have a few Qt applications running on the screen, but have no way to interract with the GUI, since we have no mouse/touchscreen driver.

My question is this:  what layer(s) connect the touchscreen with Qt, and what are the interfaces between these layers.  I can read out touchscreen readings in the FPGA, but do not know how Qt needs this information in order to design a device driver for this interface.

Thanks in advance for any help!

-John

  • 0
    Prodigy 30 points

    Also, if something in my question is unclear, badly phrased, or too broad, let me know how i can improve my question for next time!  I am new to forums, so guidance on what the scope/length of a question should be is welcome.

  • 0 in reply to John Carpenter
    TI__Intellectual 1275 points

    Hi,

    I do not know about QT, but I assume it should also be waiting for input events from touchscreen device. You can have a look at evtest utility, which is used for generic input device validation.

    Thanks,

    Prakash

  • 0 in reply to Prakash PM
    Prodigy 30 points

    Thank you so much for a response!

    Do I have to explicitly handle this in Qt?  I was under the impression that Qt could handle mouse/keyboard event "behind the scenes".  For instance, when I create a Qt application for a system with just a mouse and keyboard, Qt handles them and implicitly knows when a button is hovered over or a key is pressed without any code in the Qt application monitoring the mouse or keyboard.

    I read about this library called Tslib, does Qt use Tslib to make the touchscreen look like a mouse from Qt's perspective?

    Thanks again in advance for your response,

    John