ABSTRACT
Four-wire resistive touch screens have been widely used in electronic products. In this paper, we introduce the theory of resistive touch screens and the working principle of the touch screen controller ADS7843, construct the hardware interface circuit design for the touch screen with the MCU of MSP430, calculate the X–Y position of the touched point and figure out the calibration algorithm for the touch screen based on four points of the touch position. The reliability of the algorithm has been proved by much testing data. The designed circuit in this paper uses MSP430F149 to control a 7” touch screen LCD of 800 × 480 pixels and the presented algorithm works well in practical application.
