320*240 resistive touch screen calibration problem

Hi every one.

I have 320*240 LCD with resistive touch screen and touch screen controller of AD7843 ( All is together in one LCD from topway: KM2088S). I want to know what is the best way to calibrate the touch screen? when I push the touch screen a little bit it shows me a number, but when I push it harder it shows me a different number!! how can I solve it? Is it going to solve by calibration? I really appreciate if you guys can help me.

Regards

Arash

Parents
  • Hi Arash-

    I checked with my contact here for resistive touch screen controllers and they provided the following information:

    I would suggest measuring pressure as well as the X and Y coordinates. This can only be done with the AD7873 but this part is pin-to-pin compatible with the AD7843. Would it be possible to replace the AD7843 with the AD7873?

    Also, to improve the accuracy of the AD7843, usually, some averaging of the X and Y position is a good idea. The touch screens, due to their mechanical construction, can bounce a bit, so most customers perform some sort of averaging on the result. For the AD7843, the averaging must be done in the host.

    Since there is not a specific community on EngineerZone to support this, if you have further questions on this topic, I suggest contacting your local Analog Devices support center listed at http://www.analog.com/support.

    Regards,

    AndyR

    EngineerZone Community Manager

Reply
  • Hi Arash-

    I checked with my contact here for resistive touch screen controllers and they provided the following information:

    I would suggest measuring pressure as well as the X and Y coordinates. This can only be done with the AD7873 but this part is pin-to-pin compatible with the AD7843. Would it be possible to replace the AD7843 with the AD7873?

    Also, to improve the accuracy of the AD7843, usually, some averaging of the X and Y position is a good idea. The touch screens, due to their mechanical construction, can bounce a bit, so most customers perform some sort of averaging on the result. For the AD7843, the averaging must be done in the host.

    Since there is not a specific community on EngineerZone to support this, if you have further questions on this topic, I suggest contacting your local Analog Devices support center listed at http://www.analog.com/support.

    Regards,

    AndyR

    EngineerZone Community Manager

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