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Author Topic: Touch screen sensitivity  (Read 881 times)
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Hi all,
  I recently bought a tft touch screen from Sainsmart:

http://www.sainsmart.com/arduino-compatibles-1/lcd-module/sainsmart-3-2-tft-lcd-display-touch-panel-pcb-adapter-sd-slot-for-arduino-2560.html

I'm using it with a Sainsmart Mega clone and shield (it was all in a bundle from them). I tried testing it using Henning Karlsen's touch library:

http://henningkarlsen.com/electronics/library.php?id=55

But it seems the touch screen is not that sensitive. I can see there is a setting in the code for the precision of the touch library, and a calibration one. I've calibrated it and tried various precision settings. But sometimes it seems that it just doesn't register my touches. Sometimes on the example drawing app I touch it and there is a single dot, sometimes lots of dots. On the example with buttons I sometimes had to tap it multiple times to get the buttons to register a tap.

Any idea on how to improve the sensitivity? Is this an issue with the hardware itself, or likely to be a software/library issue?

-Matt
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Is your outer screen tight against the LCD?
I had received one and it's outer screen had a slight raise to it.
If this is the case for you tell them and they should exchange it if the purchase was recent.
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I have got a similar problem and I solved it by the following way :

I have solved the problem by canceling, in the UTouch.cpp file, the line 113 :
/*        if (!((temp_x>max(touch_x_left, touch_x_right)) or (temp_x==0) or (temp_y>max(touch_y_top, touch_y_bottom)) or (temp_y==0)))*/

It works fine and without, for me, any side effect.

But it is not a very nice way.

Write to sainsmart and they will send you a modified version of UTouch that solve the problem.

Sincerely.

Pierre
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Check out http://forum.arduino.cc/index.php?topic=198188.0.  I had the same problem and had to add a delay after
myTouch.dataAvailable().
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I have the sainsmart 3.2TFT with the Mega, and the latest UTouch and UTFT  work fine for me. No special version from Sainsmart is required.
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