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help with CFAG240128LTMITZTS

lpstech

New member
i need help trying to figure out how to wire the touch screen such as what other stuff do i need to buy and how to wire it. the only thing i have right now is the CFAG240128LTMITZTS.
can anyone help me?
thank you.
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CF Support

Administrator
The touch screen is an "Analog 4-wire" and there is no controller on board.

The touch screen must be driven in one direction, then read in the other direction. TI makes a low-level part that has the drivers and ADC built into one part. Some micros have analog inputs that may work directly. There is a company http://www.tsharc.com/ that makes a high-level controller from a pre-programmed PIC micro.

Basically you put a gradient across one set of electrodes (both set as digital outputs, drive one high and the other low), then you look at either of the other set of electrodes (both set as inputs, at least one analog). The analog input will pick up the voltage of the gradient at the contact point. To read the other channel, you just rotate the whole process 90 degrees:

http://www.elotouch.com/products/accutec/accworks.asp

This description is just a conceptual outline, I am sure there are many other nuances to be addressed (references, calibration, drift, non-contact,detecting "taps" and "double-taps").

Some diagrams of 4-wire:

http://www.amtouch.com.tw/products....=15&PName=Resistive Touch Screen Construction

Here is a bunch of book-marks on touchscreen controllers:

http://www.howstuffworks.com/question716.htm
http://www.analog.com/en/subCat/0,2879,760%5F1085%5F0%5F%5F0%5F,00.html
http://www.maxim-ic.com/solutions/touchscreen_controllers/index.mvp
http://focus.ti.com/docs/prod/folders/print/ads7843.html
http://focus.ti.com/docs/prod/folders/print/tsc2003.html
http://www.tsharc.com/
http://www.national.com/mpf/LM/LM8300.html
 
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