CRTOUCH Datasheet, PDF (7/68 Pages) Freescale Semiconductor, Inc – Capacitive and Resistive Touch Sensing Application Specific IC.

Functional Description
2 Functional Description
The capacitive and resistive touch (CRTouch) is a device capable of interfacing with 4-wire and 5-wire resistive touch screens.
It is capable of detecting single touch slide and two-touch rotate and pinch gestures. CRTouch includes a calibration procedure
to increase the touch detection accuracy and configurable low power and shutdown modes to reduce power consumption.
2.1 CRTouch resistive touchscreen scanning
2.1.1 Touchscreen electrical signals
The types of resistive touchscreen supported by this device are passive elements composed of two layers of conductive material
uniformly distributed across the screen . Due to the resistivity of the conductive material, it can be seen as a resistor between
the terminals of each layer. The following figure shows the construction of the 4 and 5 wire types of screens, and their simplified
electrical equivalent circuit.
Figure 4. Construction and electrical equivalent of a four wire touchscreen
Figure 5. Construction and electrical equivalent of a five wire touchscreen
CRTouch Data Sheet, Rev. 3
Freescale Semiconductor
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