Controlling circuit of the touch control screen make short biography

The touch control screen is a common feature in modern electronic products, typically incorporating a colored liquid crystal display (LCD) with a touch-sensitive interface. This technology is user-friendly and effectively replaces traditional fixed keypads. This document introduces the driving circuit for a touch control screen, which has been developed recently. The structure of the touch control screen consists of a touch-sensitive layer combined with a liquid crystal display. Various types of liquid crystal displays exist based on color, material, and design; this document specifically refers to a 16-bit semitransparent reflecting type TFT LCD. Touch screens are primarily classified into two categories: capacitive and resistive.

Capacitive touch screens operate through the electrical induction of the human body, offering a long lifespan and requiring minimal pressure to activate. They are durable and resistant to wear but have lower precision and can be affected by environmental factors such as temperature and humidity. In contrast, resistive touch screens determine position by measuring resistance along the axes when pressed. They offer high precision and good resistance to interference, can be activated by any object, but are prone to abrasion and require more pressure to operate. The resistive touch screen is the focus of this document.

Recommended integrated circuits for touch control include the ADS7846, ADS7843, and TSC2046, which are common four-wire touch-sensitive screen controllers. These chips, originally developed by BURR-BROWN and now available through Texas Instruments (TI), are pin-compatible with differing internal functionalities, such as integrated temperature sensing and pressure measurement. The TSC2046 is a newer, cost-effective option widely used in consumer electronics like MP3 players and mobile phones.

The operating principle involves the ADS7846's PEN pin being pulled low upon touch, which interrupts the STM32 microcontroller to process the touch event. The device samples the X and Y coordinates continuously for ten cycles; if fewer than ten samples are obtained, no action is taken. Once ten samples are collected, the data is averaged to determine the final X and Y coordinates. The corresponding point on the touch screen is then activated, allowing for interaction. The STM32 driver program has been enhanced with drawing board functionality, written in the C programming language, facilitating easy adaptation.

The touch control screen technology represents a significant advancement in user interface design, enhancing the interactivity and functionality of electronic devices. The integration of touch-sensitive screens into various applications demonstrates their versatility and importance in modern electronics. The choice between capacitive and resistive types depends on the specific application requirements, including factors like precision, durability, and environmental resilience.The touch control screen is not any fresh thing, present electronic product basically all have a colored liquid crystal greatly, add a touch type touch control screen. It is very convenient to use, can totally replace that kind of fixed key set in the past. Introduced the driving circuit of a kind of touch control screen as follows, I just worked out this small board an hour ago too, will publish this daily record at once after succeeding in test, fresh and hot! First of all, introduce the structures of the following contact control screens, it was cohered together by a contact control screen and a liquid crystal display screen.

Liquid crystal display screen according to color, material, last way classification, various in style, does not introduce to the liquid crystal screen in detail here, that used is the display screen of dot matrix of 16Bit semitransparent reflecting type TFT liquid crystal in this text picture. And touch the screen and is mainly divided into two big classes, including capacitive and resistance type.

The capacitive touch control screen carries on the work by the induction by current of the human body, the advantage is to have long performance life, does not need to exert oneself while touching, the faceplate is hard and wear-resisting; The shortcoming is to touch the precision low, it is touching activated to use the particular medium such as the human skin, Exerted a tremendous influence by the temperature humidity, there is the external world relatively at the time of the electric field of high-intensity magnetic fields, the touch control screen will not work, to put it briefly anti-interference is discrepancy. The resistance type touch control screen makes use of resistance quantity of the axis of ordinates and abscissa axis while pressing to be positioned, the advantage is that the anti-interference is good, it is high to touch the precision, can touch with any object, the shortcoming is that a surface is a plastic film, apt to abrade, it is to need a little efforts to press a little to touch.

It was resistance type touch control screen that used in this text. And then recommend some several touch control screens to control IC: ADS7846, ADS7843 and TSC2046, they are the most common four-wire touch-sensitive screen control chips, it is BURR-BROWN have already purchase by TI, go to TI to look for while looking for and capsulating the storehouse The products of the company, the three pin is compatible, but one slice of inner functions is discriminating, for example the integrated temperature is sensory, can be measured and touched functions such as the pressure, etc. , please consult DataSheet specifically in 7846. TSC2046 is a control chip offered newly, because the country produces one slice of prices cheap among themretail about 1 yuan / slice, The ones that applied to producing in China are electronic products such as MP3, mobile phone which touches the screen, etc.

extensively. Operating principle: Push the touch-sensitive screen each time, PEN foot of ADS7846 will be drawn low, touches off STM32 to cut off, then deal with carrying out the function inside the interrupt service routine. The principle of drawing is through to ten times X, Y-corrdinate continuous sampling in cutting off, if not enough ten times, do not do any operation.

After getting data ten times, arrange in an order, the cubic data calculate mean value the middle fetching finally, receive required X, Y-corrdinate. After getting the point of the touch screen, then some is drawn on the screen on this correspondent point.

And unary coin little a bit behind the part that cut out, appear, right side whether the intersection of sulfuric acid and paper print negative that come out. Stick the intersection of touch-sensitive screen and driver program of STM32 finally Have already added the function of the drawing board, With what language C is written, very apt to transplant, i

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