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> Android Porting : Trouble With Touchscreen
joey
post Jan 28 2008, 08:16 PM
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Hello all,

I am porting android to my ARM9 device and am having problems getting
the touchscreen to work. On my device the touchpanel driver passes
absolute X/Y co-ordinate values to the kernel input subsystem. When i
touch the screen, more often than not , nothing happens. But on rare
occassions the main screen left/right scroll button might move or the
browser "google search" button might get pressed - but even for this i
have to give a real good thumb press, a firm tap is not enough.


I ran open source program evtest (which is an input event tester) and
it reported the co-ordinates of all my touches.


I then ran strace for the zygote process - i noticed that all of my
taps/touches/presses are read() by some thread which opens the /dev/
input/event1 device, but no action is taken on the reported events.


I also modified the (touchpanel) hardware reported raw X/Y co-ordinate
values so that they correspond to the screen size (640x480 landscape)
and then passed these values to the kernel input subsytem, but there
was no change in behaviour.


I have read on some posts about "porting tslib" - what is this for ?
Is it required here ? Also some posts mention "normarlization of the
coordination" and "auto calibration using sysfs" - what do they
mean ?


Any pointers/help would be appreciated


Regards
Joey

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joey
post Feb 5 2008, 08:13 PM
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Group: Members
Posts: 5
Joined: 28-January 08
Member No.: 21,291



My touchscreen driver was incorrectly initialising the ABS_X [MIN/MAX], ABS_Y [MIN/MAX] values - these were supposed to be initialised according to the dimensions of the VGA panel (640x480) i am using. Also i had to calibrate the hardware reported X/Y values according to the 640 x 480 screen - i now pass these calibrated values (alongwith pressure value) to the input subsystem. My touch screen works fairly well now.
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