The Design And Implementation Of Five-wire Touch Screen Controller Based On Linux

With simple and convenient features in the public information inquiry, industrial control and life electronic products, the touch screens are widely used. This thesis has discussed how to design and implement the five-wire touch screen controller on Linux platform based on USB2.0 controlling IC chip FS7803 R&D by FameG itself and 12-bit sampling analog-to-digital converter IC chip ADS7845 of Texas Instruments. The thesis has summarized the achievements by this author and described in detail to three parts of the solutions: USB drive layer development, XF86 driver layer development and the design of calibration arithmetic for five-wire touch screen controller on Linux platform.Based on the analysis of IC chip FS7803 and IC chip ADS7845, and the chip agreement of SPI and I2C, the author has successfully finished the entire design of five-wire touch screen controller as well as the technical implementation way. More over, the author also fulfilled the hardware design of the circuit and the firmware for this five-wire touch screen controller. Based on study of Texas Instruments'technique on touch screen calibration algorithm, the author finally designed the four-point correction algorithm, which solved the error caused by the inconsistent of the inverse proportion coefficient and machine.This thesis fulfilled the design of entire system software and divided it into three parts: USB driver layer, XF86 driver layer and high software layer.In the part of USB driver layer and XF86 driver layer realization, the author focused on USB drives and XF86-driven architecture in the Linux operating system. And in the part of USB drive layer, the author implemented the data communication between PC and five-wire touch screen controller. In the part of XF86 driver layer, the author completed the transformation of data issued up from USB driver layer to the mouse's movement. In the part of high-end layer of software, the author realized the touch screen calibration algorithm, the phonic control when mouse pressed down or poped up, and many mouse action events handling procedures such as the triggle time and enabling.The design of five-wire touch screen controller based on Linux now successfully applied in projects such as the Multimedia In-car System,the Netbook and so on. Although there are still many deficiencies between our device and the professional touch-screen controller in function, but our device has manifested its own application superiority in the specific domain.