The data processing process of capacitive touch screen

After receiving the touch signal, the capacitive touch screen converts the touch data into electrical pulses and transmits them to the touch screen control IC for processing. The signal is first amplified by a low-noise amplifier (LNA), then converted and demodulated through analog-to-digital conversion, and finally sent to a DSP for data processing.
Capacitive touch screens generally have M+N (M columns N rows) physical capacitive touch sensors. These M+N interlaced sensors form M * N capacitive sensing points, and when the user's finger approaches the touch screen, its capacitance will change accordingly. The spacing between sensors (i.e. the distance between adjacent rows or columns) is usually around a few millimeters, which determines the physical resolution M * N of the touch screen. 
The coordinate system between the capacitive touch screen module and the LCD module is completely different. The pixel coordinates of an LCD module are generally determined by its resolution. For example, a WVGA screen has a resolution of 800 * 480, which means there are 800 rows with 480 RGB pixels per row. Thus, a specific position can be determined by the pixel points (x, y) in the X and Y directions. The capacitive touch screen module determines the coordinate system based on its original physical dimensions in the X and Y directions. There must be a reasonable mapping method between two coordinate systems to ensure the correctness of input and output operations.
So, the DSP processor of the touch screen control IC also needs to perform pixel mapping conversion between the capacitive touch screen module and the LCD module on the obtained data, so as to ensure that the touch point sensed by the user on the touch screen is the point pointed by the user.
In addition, in order to maintain the stability of touch coordinates, the touch screen control IC needs to further handle the shaking of touch points, including finger shaking and noise in capacitance data, and change the filtering coefficient of the low-pass filter according to the changes in coordinates to achieve smooth processing of coordinates.
Finally, before transmitting the data to the host, software must be used to analyze the data and determine what function each touch is intended for. This process involves determining the size, shape, and position of the touched area on the screen. If necessary, the processor will organize and group similar touches. If the user moves their finger, the processor will calculate the difference between the starting and ending points of the user's touch.