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  • Touch status funnies

    Hi,
    In my application there are some screens which are loaded with DisplayImageIconFromCard (0x40,0x6D) from a file. It's a 480x272 display so loading the image takes an appreciable time, aorund half a second.

    I wanted an auto-repeat feature for some touchscreen buttons that are used to set the date.

    So on TouchPress, I set a downcounter to 500. The downcounter is decremented at 1kHz and when it gets to zero, if I read TouchMoving from the screen (without an intervening TouchRelease) I pretend that the user has touched the screen again, and set the downcounter to 250.

    My problem is that the touch which calls up the screen may only last about 200ms, but after the new screen has been drawn (500+ms later) I call GetTouchStatus and it returns TouchMoving. Clearly the screen has buffered the touch info. Even if I call GetTouchStatus again immediately I still get TouchMoving. I have to call GetTouchStatus, wait 10ms (5ms is not enough) and then call GetTouchStatus again to get the true current TouchStatus.

    I think your manual could do with some explanation on this point, it took all morning to figure out.

    Cheers,

    Mark

  • #2


    Are you using the latest PmmC?

    There were issues like this with an older PmmC
    Mark

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    • #3


      The hardware revision is 16 and the software is 34. I guess this translates to 1.0 and 2.2 ?

      I'd guess that each call to GetTouchStatus returns the last touch status and kicks off a new measurement of the touch status, which takes 5 to 10ms to complete.

      Cheers,

      Mark

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      • #4


        Unfortunately the displays that have a separate touch processing chip (the 43 displays) behave differently to the other displays.

        The touch processing chips effectively buffer one 'report', which is one 'problem' you are seeing.

        There is also no way to 'force' a 'current' report, you have to 'wait' until the touch chip issues its next 'report', this is why you are only seeing an update every 10ms or so.

        Hope that helps understand why it seems a bit 'odd' at times
        Mark

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