avr lcd touch screen free sample

Description:This 7.0" TFT LCD Module can be can be easy controlled by MCU such as 51,AVR,STM32,PIC,MSP430,DSP,ARM, and ARM .It can be used in any embedded systems which require display high quality colorful image. The Module used

SSD1963 LCD controller with 7 inch LCD module with touchscreen. This LCD has a superior display quality and super wide viewing angle, please see the sample pictures, they are taken directly from the LCD display.

LCD Type: TFT Transmissive Normal White Interface: 16bit parallel bus interface PCB Color: Blue On board 400mA DC-DC Boost regulator to provide power supply to LCD backlight LCD-specificed intialization code is provided, so that you can save time to optimize power control register and gamma curves for best display performance. We have test the provided code, it gives the best display performanace Module dimension: 186mmx106mmx23mm(including pin header extrusion) Active Area: 154mmx86mm Pixel pitch: 0.179mmx0.179mm Standard 2x20 2.54mm pin header for connection to MCU/development board Module weight: 410grams Warning: All data port voltage can not exceed 3.6V.

ER-TFTM070-4V2.1 is the updated version of ER-TFTM070-4,that is 800x480 dots 7" color tft lcd module display with ssd1963 controller board,superior display quality,super wide viewing angle and easily controlled by MCU such as 8051, PIC, AVR, ARDUINO, and ARM .It can be used in any embedded systems,industrial device,security and hand-held equipment which requires display in high quality and colorful image.

It supports 6800, 8080 8-bit /9-bit/16-bit/18-bit/24-bit parallel interface.Built-in MicroSD card slot.It"s optional for resistive touch panel and controller XPT2046,capacitive touch panel and controller FT5206, font chip, flash chip and microsd card. We offer two types connection,one is pinheader and the another is ZIF connector with flat cable mounting on board by default and suggested.

Of course, we wouldn"t just leave you with a datasheet and a "good luck!".Here is the link for7" TFT capacitive touch shield with libraries,examples,schematic diagram for Arduino Due,Mega 2560 and Uno. For 8051 microcontroller user,we prepared the detailed tutorial such as interfacing, demo code and development kit at the bottom of this page.

HY-TFT320 is a 3.2 inch TFT LCD Screen module, 320*240 (resolution), 65K color, 34pins interface , not just a LCD breakout, but include the Touch screen, SD card. So it’s a powerful extension module for your project.

This Screen includes a controller SSD1289, it’s 16bit data interface, easy to drive by many MCU like STM32 ,AVR and 8051.HY-TFT320 is designed with a touch controller in it . The touch IC is XPT2046 , and touch interface is included in the 34 pins breakout. Another useful extension in this module is the SD Card socket . It use the SPI mode to operate the SD card, the SPI interface include in the 40pins breakout.

The UTFT library is required to be installed to get this screen model display. This library is especially designed for 3.2” TFT LCD screen using 16 bit mode. The library require the following connections.

Note: The TFT controller model needs to be declared in the initializing statement. ITDB02 myGLCD(38,39,40,41) needs to be modified as myGLCD(38,39,40,41,ITDB32S) when using Arduino Mega2560.ITDB02 myGLCD(19,18,17,16,ITDB32S) needs to be commented when using Aduino UNO. Otherwise it just show a blank screen. In practice, RS, WR, CS, RSET can be connected to any free pin. But the pin number must be in accord with myGLCD(RS,WR,CS,RST).

The LCD has a 3.2" 4-wire resistive touch screen lying over it. The Touch libraryneeds to be installed to get it works. This library is designed for 2.4’’ TFT, 3.2” TFT LCD screen module.

Note:TCLK, TCS, TDIN, TDOUT, IRQ also can be connected to any free pin. But the pin number must be in accord with the touch screen initializing statement myTouch(DCLK,CS,IN,OUT,IRQ).

The default setting is accurate for 2.4” TFT module, but you need to calibrate when using 3.2” TFT module. A program to calibrate the touch screen is included in the example. If you touch screen is inaccurate, you need to run touch_calibration. Follow the on-screen instruction to calibrate the touch screen. Better not use your finger to calibrate it, use your accessory touch pen to pressure the frontsight with stength. Then record the calibration parameters and apply them in ITDB02_Touch.cpp in your touch screen library.

This tutorial shows how to use the I2C LCD (Liquid Crystal Display) with the ESP32 using Arduino IDE. We’ll show you how to wire the display, install the library and try sample code to write text on the LCD: static text, and scroll long messages. You can also use this guide with the ESP8266.

Additionally, it comes with a built-in potentiometer you can use to adjust the contrast between the background and the characters on the LCD. On a “regular” LCD you need to add a potentiometer to the circuit to adjust the contrast.

Before displaying text on the LCD, you need to find the LCD I2C address. With the LCD properly wired to the ESP32, upload the following I2C Scanner sketch.

Displaying static text on the LCD is very simple. All you have to do is select where you want the characters to be displayed on the screen, and then send the message to the display.

The next two lines set the number of columns and rows of your LCD display. If you’re using a display with another size, you should modify those variables.

To display a message on the screen, first you need to set the cursor to where you want your message to be written. The following line sets the cursor to the first column, first row.

Scrolling text on the LCD is specially useful when you want to display messages longer than 16 characters. The library comes with built-in functions that allows you to scroll text. However, many people experience problems with those functions because:

In a 16×2 LCD there are 32 blocks where you can display characters. Each block is made out of 5×8 tiny pixels. You can display custom characters by defining the state of each tiny pixel. For that, you can create a byte variable to hold  the state of each pixel.

In summary, in this tutorial we’ve shown you how to use an I2C LCD display with the ESP32/ESP8266 with Arduino IDE: how to display static text, scrolling text and custom characters. This tutorial also works with the Arduino board, you just need to change the pin assignment to use the Arduino I2C pins.

LCD stands for Liquid Crystal Display. It can be used to display anything (virtually anything!). They are of many types. The ones we commonly use for embedded systems, robotics, etc are of two types – character LCD and graphical LCD. We will discuss about character LCDs in this post whereas graphical LCDs will be discussed later.

The most popular type of character LCD is the HD44780 Character LCD. In this post, we will be using the JHD 162A character LCD shown below. One of my readers, Rizwan, has also worked out this tutorial successfully using the LMB162ABC character LCD. Thanks Rizwan for the update! :)

The JHD 162A LCD is fully compatible with the HD44780 LCD. Hence, the same set of codes will work for both. It is a 16×2 LCD module i.e. it has 16 columns and 2 rows for display. It can operate in either 8 bit mode or 4 bit mode. In 8 bit mode, an 8 bit is data is sent to the LCD from the MCU whereas in 4 bit mode, 4 bits of data are sufficient to operate it.

Now, for the LCD to work in 8 bit mode, it requires the 8 data pins (DB0…DB7) and 3 control pins (RS, R/W, EN) whereas in 4 bit mode, it requires 4 data pins (DB4…DB7, only the upper nibble) and 3 control pins (RS, R/W, EN). Though the 8 bit mode is faster and more accurate, it consumes more pins of the MCU. However, the 4 bit mode is also fast and accurate enough to satisfy most of our need, plus it requires only 7 pins for interfacing. Hence, we will be working in the 4 bit mode. In the 4 bit mode, data pins DB0…DB3 are left open.

First of all, you need to make basic connections of the LCD. You can refer to the following circuit diagram for this. Relate it with the pin configuration given above.

Before coding, kindly download the LCD library written by Peter Fleury from here. This is an awesome library with predefined codes so that we can ease out a little bit by not breaking our heads upon the coding part. Thus we get to use the library functions instead of going into the depths of programming. This method is much more productive, efficient and time saving. At this point, don’t worry about how a library is written. May be in days to come, I’ll teach you that as well. ;)

Now that we are ready for programming, open up AVR Studio 5 and create new project. If you are new to AVR Studio 5, view this page to get started. Now in the right pane, you will find the Solution Explorer window. There, right click on the project name, go to Add and then choose Existing Item…. Now browse to the folder where you have downloaded the libraries and choose lcd.c and lcd.h.

Double click on the ‘lcd.h’ file (in the Solution Explorer) to open it. Now make sure that you scroll down very slowly or else you will miss out on some important details.

As you begin to scroll down, you will find some commented text describing the library. Note the line where it says LCD_IO_MODE = 0 for memory mapped mode, LCD_IO_MODE = 1 for 4 bit mode, whereas 8 bit mode is not supported.

Just below it lies the best part. You can choose your own port where to interface the LCD with! As I said earlier, in 4 bit operation, there will be 4 data pins (DB4…DB7) and 3 control pins (RS, R/W, EN). You can either choose them to be across one port, or distributed across different ports. This is where you do it. By default it’s across PORTA. Choose them as per your pin availability.

Now, if you continue to scroll, you will find a list of all the functions defined in the library along with their description. You will find functions like lcd_init(), lcd_clrscr(), lcd_home(), lcd_gotoxy(), lcd_putc(), lcd_puts(), lcd_puts_p(), lcd_command(), lcd_data() and lcd_puts_P(). Their description is attached alongwith their declaration.

After building the project and burning your code, you will see “hello” written in the first row and “maxEmbedded” written in the second row. This was a basic example. Now it’s up to you upon how to exploit the library resources. Okay, try this one out by yourself. The LCD should display your in the first line, and then create a bouncing effect. Your name should move towards right till it reaches the corner. And then it should move left till it once again reaches the other corner. This should continue. Hint: Use lcd_command() function e.g. lcd_command(LCD_MOVE_DISP_RIGHT), lcd_command(LCD_MOVE_DISP_LEFT), etc.

One drawback of Fleury’s library is that the is no function which can directly display an integer or floating point value on the LCD. For that, we can use lcd_puts() itself in combination with itoa() and sprintf() funtions.

Displaying a custom image or graphic on a LCD display is a very useful task as displays are now a premium way of providing feedback to users on any project. With this functionality, we can build projects that display our own logo, or display images that help users better understand a particular task the project is performing, providing an all-round improved User Experience (UX) for your Arduino or ESP8266 based project. Today’s tutorial will focus on how you can display graphics on most Arduino compatible displays.

The procedure described in this tutorial works with all color displays supported by Adafruit’s GFX library and also works for displays supported by the TFTLCD library from Adafruit with little modification. Some of the displays on which this procedure works include:

Before an image is displayed on any of the Arduino screens, it needs to be converted to a C compatible hex file and that can only happen when the image is in bitmap form. Thus, our first task is to create a bitmap version of the graphics to be displayed or convert the existing image to a bitmap file. There are several tools that can be used for creation/conversion of bitmap images including, Corel Draw and Paint.net, but for this tutorial, we will use the Paint.net.

Image2Code is an easy-to-use, small Java utility to convert images into a byte array that can be used as a bitmap on displays that are compatible with the Adafruit-GFX or Adafruit TFTLCD (with little modification) library.

Paste the bit array in the graphics.c file and save. Since we have two graphics (the car and the text), You can paste their data array in the same file. check the graphics.c file attached to the zip file, under the download section to understand how to do this. Don’t forget to declare the data type as “const unsigned char“, add PROGEM in front of it and include the avr/pgmspace.h header file as shown in the image below.  This instructs the code to store the graphics data in the program memory of the Arduino.

To reduce the amount of code, and stress involved in displaying the graphics, we will use two wonderful libraries; The GFX library and the TFTLCD library from Adafruit.

The first two are thex and y coordinates of a point on the screen where we want the image to be displayed. The next argument is the array in which the bitmap is loaded in our code, in this case, it will be the name of the car and the text array located in the graphics.c file. The next two arguments are the width and height of the bitmap in pixels, in other words, the resolution of the image. The last argument is the color of the bitmap, we can use any color we like. The bitmap data must be located in program memory since Arduino has a limited amount of RAM memory available.

As usual, we start writing the sketch by including the libraries required. For this procedure, we will use the TFTLCD library alone, since we are assuming you are using a display that is not supported by the GFX library.

The last section of the code is the drawBitmap function itself, as earlier mentioned, to use the drawbitmap() function with the Adafruit TFTLCD library, we need to copy the function’s code and paste into the Arduino sketch.

Plug in your screen as shown above. If you are using any other display, connect it as shown in the corresponding linked tutorial. With the schematics in place, connect the Arduino board to your PC and upload the code. Don’t forget the graphics file needs to be in the same folder as the Arduino sketch.

A touchscreen or touch screen is the assembly of both an input ("touch panel") and output ("display") device. The touch panel is normally layered on the top of an electronic visual display of an electronic device.

A user can give input or control the information processing system through simple or multi-touch gestures by touching the screen with a special stylus or one or more fingers.zooming to increase the text size.

The touchscreen enables the user to interact directly with what is displayed, rather than using a mouse, touchpad, or other such devices (other than a stylus, which is optional for most modern touchscreens).

Touchscreens are common in devices such as smartphones, handheld game consoles, personal computers, electronic voting machines, automated teller machines and point-of-sale (POS) systems. They can also be attached to computers or, as terminals, to networks. They play a prominent role in the design of digital appliances such as personal digital assistants (PDAs) and some e-readers. Touchscreens are also important in educational settings such as classrooms or on college campuses.

The popularity of smartphones, tablets, and many types of information appliances is driving the demand and acceptance of common touchscreens for portable and functional electronics. Touchscreens are found in the medical field, heavy industry, automated teller machines (ATMs), and kiosks such as museum displays or room automation, where keyboard and mouse systems do not allow a suitably intuitive, rapid, or accurate interaction by the user with the display"s content.

Historically, the touchscreen sensor and its accompanying controller-based firmware have been made available by a wide array of after-market system integrators, and not by display, chip, or motherboard manufacturers. Display manufacturers and chip manufacturers have acknowledged the trend toward acceptance of touchscreens as a user interface component and have begun to integrate touchscreens into the fundamental design of their products.

The prototypeCERNFrank Beck, a British electronics engineer, for the control room of CERN"s accelerator SPS (Super Proton Synchrotron). This was a further development of the self-capacitance screen (right), also developed by Stumpe at CERN

One predecessor of the modern touch screen includes stylus based systems. In 1946, a patent was filed by Philco Company for a stylus designed for sports telecasting which, when placed against an intermediate cathode ray tube display (CRT) would amplify and add to the original signal. Effectively, this was used for temporarily drawing arrows or circles onto a live television broadcast, as described in US 2487641A, Denk, William E, "Electronic pointer for television images", issued 1949-11-08. Later inventions built upon this system to free telewriting styli from their mechanical bindings. By transcribing what a user draws onto a computer, it could be saved for future use. See US 3089918A, Graham, Robert E, "Telewriting apparatus", issued 1963-05-14.

The first version of a touchscreen which operated independently of the light produced from the screen was patented by AT&T Corporation US 3016421A, Harmon, Leon D, "Electrographic transmitter", issued 1962-01-09. This touchscreen utilized a matrix of collimated lights shining orthogonally across the touch surface. When a beam is interrupted by a stylus, the photodetectors which no longer are receiving a signal can be used to determine where the interruption is. Later iterations of matrix based touchscreens built upon this by adding more emitters and detectors to improve resolution, pulsing emitters to improve optical signal to noise ratio, and a nonorthogonal matrix to remove shadow readings when using multi-touch.

The first finger driven touch screen was developed by Eric Johnson, of the Royal Radar Establishment located in Malvern, England, who described his work on capacitive touchscreens in a short article published in 1965Frank Beck and Bent Stumpe, engineers from CERN (European Organization for Nuclear Research), developed a transparent touchscreen in the early 1970s,In the mid-1960s, another precursor of touchscreens, an ultrasonic-curtain-based pointing device in front of a terminal display, had been developed by a team around Rainer Mallebrein[de] at Telefunken Konstanz for an air traffic control system.Einrichtung" ("touch input facility") for the SIG 50 terminal utilizing a conductively coated glass screen in front of the display.

In 1972, a group at the University of Illinois filed for a patent on an optical touchscreenMagnavox Plato IV Student Terminal and thousands were built for this purpose. These touchscreens had a crossed array of 16×16 infrared position sensors, each composed of an LED on one edge of the screen and a matched phototransistor on the other edge, all mounted in front of a monochrome plasma display panel. This arrangement could sense any fingertip-sized opaque object in close proximity to the screen. A similar touchscreen was used on the HP-150 starting in 1983. The HP 150 was one of the world"s earliest commercial touchscreen computers.infrared transmitters and receivers around the bezel of a 9-inch Sony cathode ray tube (CRT).

In 1977, an American company, Elographics – in partnership with Siemens – began work on developing a transparent implementation of an existing opaque touchpad technology, U.S. patent No. 3,911,215, October 7, 1975, which had been developed by Elographics" founder George Samuel Hurst.World"s Fair at Knoxville in 1982.

In 1984, Fujitsu released a touch pad for the Micro 16 to accommodate the complexity of kanji characters, which were stored as tiled graphics.Sega released the Terebi Oekaki, also known as the Sega Graphic Board, for the SG-1000 video game console and SC-3000 home computer. It consisted of a plastic pen and a plastic board with a transparent window where pen presses are detected. It was used primarily with a drawing software application.

Touch-sensitive control-display units (CDUs) were evaluated for commercial aircraft flight decks in the early 1980s. Initial research showed that a touch interface would reduce pilot workload as the crew could then select waypoints, functions and actions, rather than be "head down" typing latitudes, longitudes, and waypoint codes on a keyboard. An effective integration of this technology was aimed at helping flight crews maintain a high level of situational awareness of all major aspects of the vehicle operations including the flight path, the functioning of various aircraft systems, and moment-to-moment human interactions.

In the early 1980s, General Motors tasked its Delco Electronics division with a project aimed at replacing an automobile"s non-essential functions (i.e. other than throttle, transmission, braking, and steering) from mechanical or electro-mechanical systems with solid state alternatives wherever possible. The finished device was dubbed the ECC for "Electronic Control Center", a digital computer and software control system hardwired to various peripheral sensors, servos, solenoids, antenna and a monochrome CRT touchscreen that functioned both as display and sole method of input.stereo, fan, heater and air conditioner controls and displays, and was capable of providing very detailed and specific information about the vehicle"s cumulative and current operating status in real time. The ECC was standard equipment on the 1985–1989 Buick Riviera and later the 1988–1989 Buick Reatta, but was unpopular with consumers—partly due to the technophobia of some traditional Buick customers, but mostly because of costly technical problems suffered by the ECC"s touchscreen which would render climate control or stereo operation impossible.

Multi-touch technology began in 1982, when the University of Toronto"s Input Research Group developed the first human-input multi-touch system, using a frosted-glass panel with a camera placed behind the glass. In 1985, the University of Toronto group, including Bill Buxton, developed a multi-touch tablet that used capacitance rather than bulky camera-based optical sensing systems (see History of multi-touch).

The first commercially available graphical point-of-sale (POS) software was demonstrated on the 16-bit Atari 520ST color computer. It featured a color touchscreen widget-driven interface.COMDEX expo in 1986.

In 1987, Casio launched the Casio PB-1000 pocket computer with a touchscreen consisting of a 4×4 matrix, resulting in 16 touch areas in its small LCD graphic screen.

Touchscreens had a bad reputation of being imprecise until 1988. Most user-interface books would state that touchscreen selections were limited to targets larger than the average finger. At the time, selections were done in such a way that a target was selected as soon as the finger came over it, and the corresponding action was performed immediately. Errors were common, due to parallax or calibration problems, leading to user frustration. "Lift-off strategy"University of Maryland Human–Computer Interaction Lab (HCIL). As users touch the screen, feedback is provided as to what will be selected: users can adjust the position of the finger, and the action takes place only when the finger is lifted off the screen. This allowed the selection of small targets, down to a single pixel on a 640×480 Video Graphics Array (VGA) screen (a standard of that time).

Sears et al. (1990)human–computer interaction of the time, describing gestures such as rotating knobs, adjusting sliders, and swiping the screen to activate a switch (or a U-shaped gesture for a toggle switch). The HCIL team developed and studied small touchscreen keyboards (including a study that showed users could type at 25 wpm on a touchscreen keyboard), aiding their introduction on mobile devices. They also designed and implemented multi-touch gestures such as selecting a range of a line, connecting objects, and a "tap-click" gesture to select while maintaining location with another finger.

In 1990, HCIL demonstrated a touchscreen slider,lock screen patent litigation between Apple and other touchscreen mobile phone vendors (in relation to

An early attempt at a handheld game console with touchscreen controls was Sega"s intended successor to the Game Gear, though the device was ultimately shelved and never released due to the expensive cost of touchscreen technology in the early 1990s.

Touchscreens would not be popularly used for video games until the release of the Nintendo DS in 2004.Apple Watch being released with a force-sensitive display in April 2015.

In 2007, 93% of touchscreens shipped were resistive and only 4% were projected capacitance. In 2013, 3% of touchscreens shipped were resistive and 90% were projected capacitance.

A resistive touchscreen panel comprises several thin layers, the most important of which are two transparent electrically resistive layers facing each other with a thin gap between. The top layer (that which is touched) has a coating on the underside surface; just beneath it is a similar resistive layer on top of its substrate. One layer has conductive connections along its sides, the other along top and bottom. A voltage is applied to one layer and sensed by the other. When an object, such as a fingertip or stylus tip, presses down onto the outer surface, the two layers touch to become connected at that point.voltage dividers, one axis at a time. By rapidly switching between each layer, the position of pressure on the screen can be detected.

Resistive touch is used in restaurants, factories and hospitals due to its high tolerance for liquids and contaminants. A major benefit of resistive-touch technology is its low cost. Additionally, as only sufficient pressure is necessary for the touch to be sensed, they may be used with gloves on, or by using anything rigid as a finger substitute. Disadvantages include the need to press down, and a risk of damage by sharp objects. Resistive touchscreens also suffer from poorer contrast, due to having additional reflections (i.e. glare) from the layers of material placed over the screen.3DS family, and the Wii U GamePad.

Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the touchscreen panel. When the panel is touched, a portion of the wave is absorbed. The change in ultrasonic waves is processed by the controller to determine the position of the touch event. Surface acoustic wave touchscreen panels can be damaged by outside elements. Contaminants on the surface can also interfere with the functionality of the touchscreen.

The Casio TC500 Capacitive touch sensor watch from 1983, with angled light exposing the touch sensor pads and traces etched onto the top watch glass surface.

A capacitive touchscreen panel consists of an insulator, such as glass, coated with a transparent conductor, such as indium tin oxide (ITO).electrostatic field, measurable as a change in capacitance. Different technologies may be used to determine the location of the touch. The location is then sent to the controller for processing. Touchscreens that use silver instead of ITO exist, as ITO causes several environmental problems due to the use of indium.complementary metal–oxide–semiconductor (CMOS) application-specific integrated circuit (ASIC) chip, which in turn usually sends the signals to a CMOS digital signal processor (DSP) for processing.

Unlike a resistive touchscreen, some capacitive touchscreens cannot be used to detect a finger through electrically insulating material, such as gloves. This disadvantage especially affects usability in consumer electronics, such as touch tablet PCs and capacitive smartphones in cold weather when people may be wearing gloves. It can be overcome with a special capacitive stylus, or a special-application glove with an embroidered patch of conductive thread allowing electrical contact with the user"s fingertip.

A low-quality switching-mode power supply unit with an accordingly unstable, noisy voltage may temporarily interfere with the precision, accuracy and sensitivity of capacitive touch screens.

Some capacitive display manufacturers continue to develop thinner and more accurate touchscreens. Those for mobile devices are now being produced with "in-cell" technology, such as in Samsung"s Super AMOLED screens, that eliminates a layer by building the capacitors inside the display itself. This type of touchscreen reduces the visible distance between the user"s finger and what the user is touching on the screen, reducing the thickness and weight of the display, which is desirable in smartphones.

In this basic technology, only one side of the insulator is coated with a conductive layer. A small voltage is applied to the layer, resulting in a uniform electrostatic field. When a conductor, such as a human finger, touches the uncoated surface, a capacitor is dynamically formed. The sensor"s controller can determine the location of the touch indirectly from the change in the capacitance as measured from the four corners of the panel. As it has no moving parts, it is moderately durable but has limited resolution, is prone to false signals from parasitic capacitive coupling, and needs calibration during manufacture. It is therefore most often used in simple applications such as industrial controls and kiosks.

This diagram shows how eight inputs to a lattice touchscreen or keypad creates 28 unique intersections, as opposed to 16 intersections created using a standard x/y multiplexed touchscreen .

Projected capacitive touch (PCT; also PCAP) technology is a variant of capacitive touch technology but where sensitivity to touch, accuracy, resolution and speed of touch have been greatly improved by the use of a simple form of

Some modern PCT touch screens are composed of thousands of discrete keys,etching a single conductive layer to form a grid pattern of electrodes, by etching two separate, perpendicular layers of conductive material with parallel lines or tracks to form a grid, or by forming an x/y grid of fine, insulation coated wires in a single layer . The number of fingers that can be detected simultaneously is determined by the number of cross-over points (x * y) . However, the number of cross-over points can be almost doubled by using a diagonal lattice layout, where, instead of x elements only ever crossing y elements, each conductive element crosses every other element .

In some designs, voltage applied to this grid creates a uniform electrostatic field, which can be measured. When a conductive object, such as a finger, comes into contact with a PCT panel, it distorts the local electrostatic field at that point. This is measurable as a change in capacitance. If a finger bridges the gap between two of the "tracks", the charge field is further interrupted and detected by the controller. The capacitance can be changed and measured at every individual point on the grid. This system is able to accurately track touches.

Unlike traditional capacitive touch technology, it is possible for a PCT system to sense a passive stylus or gloved finger. However, moisture on the surface of the panel, high humidity, or collected dust can interfere with performance.

These environmental factors, however, are not a problem with "fine wire" based touchscreens due to the fact that wire based touchscreens have a much lower "parasitic" capacitance, and there is greater distance between neighbouring conductors.

This is a common PCT approach, which makes use of the fact that most conductive objects are able to hold a charge if they are very close together. In mutual capacitive sensors, a capacitor is inherently formed by the row trace and column trace at each intersection of the grid. A 16×14 array, for example, would have 224 independent capacitors. A voltage is applied to the rows or columns. Bringing a finger or conductive stylus close to the surface of the sensor changes the local electrostatic field, which in turn reduces the mutual capacitance. The capacitance change at every individual point on the grid can be measured to accurately determine the touch location by measuring the voltage in the other axis. Mutual capacitance allows multi-touch operation where multiple fingers, palms or styli can be accurately tracked at the same time.

Self-capacitive touch screen layers are used on mobile phones such as the Sony Xperia Sola,Samsung Galaxy S4, Galaxy Note 3, Galaxy S5, and Galaxy Alpha.

Self capacitance is far more sensitive than mutual capacitance and is mainly used for single touch, simple gesturing and proximity sensing where the finger does not even have to touch the glass surface.

Capacitive touchscreens do not necessarily need to be operated by a finger, but until recently the special styli required could be quite expensive to purchase. The cost of this technology has fallen greatly in recent years and capacitive styli are now widely available for a nominal charge, and often given away free with mobile accessories. These consist of an electrically conductive shaft with a soft conductive rubber tip, thereby resistively connecting the fingers to the tip of the stylus.

Infrared sensors mounted around the display watch for a user"s touchscreen input on this PLATO V terminal in 1981. The monochromatic plasma display"s characteristic orange glow is illustrated.

An infrared touchscreen uses an array of X-Y infrared LED and photodetector pairs around the edges of the screen to detect a disruption in the pattern of LED beams. These LED beams cross each other in vertical and horizontal patterns. This helps the sensors pick up the exact location of the touch. A major benefit of such a system is that it can detect essentially any opaque object including a finger, gloved finger, stylus or pen. It is generally used in outdoor applications and POS systems that cannot rely on a conductor (such as a bare finger) to activate the touchscreen. Unlike capacitive touchscreens, infrared touchscreens do not require any patterning on the glass which increases durability and optical clarity of the overall system. Infrared touchscreens are sensitive to dirt and dust that can interfere with the infrared beams, and suffer from parallax in curved surfaces and accidental press when the user hovers a finger over the screen while searching for the item to be selected.

A translucent acrylic sheet is used as a rear-projection screen to display information. The edges of the acrylic sheet are illuminated by infrared LEDs, and infrared cameras are focused on the back of the sheet. Objects placed on the sheet are detectable by the cameras. When the sheet is touched by the user, frustrated total internal reflection results in leakage of infrared light which peaks at the points of maximum pressure, indicating the user"s touch location. Microsoft"s PixelSense tablets use this technology.

Optical touchscreens are a relatively modern development in touchscreen technology, in which two or more image sensors (such as CMOS sensors) are placed around the edges (mostly the corners) of the screen. Infrared backlights are placed in the sensor"s field of view on the opposite side of the screen. A touch blocks some lights from the sensors, and the location and size of the touching object can be calculated (see visual hull). This technology is growing in popularity due to its scalability, versatility, and affordability for larger touchscreens.

Introduced in 2002 by 3M, this system detects a touch by using sensors to measure the piezoelectricity in the glass. Complex algorithms interpret this information and provide the actual location of the touch.

The key to this technology is that a touch at any one position on the surface generates a sound wave in the substrate which then produces a unique combined signal as measured by three or more tiny transducers attached to the edges of the touchscreen. The digitized signal is compared to a list corresponding to every position on the surface, determining the touch location. A moving touch is tracked by rapid repetition of this process. Extraneous and ambient sounds are ignored since they do not match any stored sound profile. The technology differs from other sound-based technologies by using a simple look-up method rather than expensive signal-processing hardware. As with the dispersive signal technology system, a motionless finger cannot be detected after the initial touch. However, for the same reason, the touch recognition is not disrupted by any resting objects. The technology was created by SoundTouch Ltd in the early 2000s, as described by the patent family EP1852772, and introduced to the market by Tyco International"s Elo division in 2006 as Acoustic Pulse Recognition.

There are several principal ways to build a touchscreen. The key goals are to recognize one or more fingers touching a display, to interpret the command that this represents, and to communicate the command to the appropriate application.

Dispersive-signal technology measures the piezoelectric effect—the voltage generated when mechanical force is applied to a material—that occurs chemically when a strengthened glass substrate is touched.

There are two infrared-based approaches. In one, an array of sensors detects a finger touching or almost touching the display, thereby interrupting infrared light beams projected over the screen. In the other, bottom-mounted infrared cameras record heat from screen touches.

The development of multi-touch screens facilitated the tracking of more than one finger on the screen; thus, operations that require more than one finger are possible. These devices also allow multiple users to interact with the touchscreen simultaneously.

With the growing use of touchscreens, the cost of touchscreen technology is routinely absorbed into the products that incorporate it and is nearly eliminated. Touchscreen technology has demonstrated reliability and is found in airplanes, automobiles, gaming consoles, machine control systems, appliances, and handheld display devices including cellphones; the touchscreen market for mobile devices was projected to produce US$5 billion by 2009.

The ability to accurately point on the screen itself is also advancing with the emerging graphics tablet-screen hybrids. Polyvinylidene fluoride (PVDF) plays a major role in this innovation due its high piezoelectric properties, which allow the tablet to sense pressure, making such things as digital painting behave more like paper and pencil.

TapSense, announced in October 2011, allows touchscreens to distinguish what part of the hand was used for input, such as the fingertip, knuckle and fingernail. This could be used in a variety of ways, for example, to copy and paste, to capitalize letters, to activate different drawing modes, etc.

For touchscreens to be effective input devices, users must be able to accurately select targets and avoid accidental selection of adjacent targets. The design of touchscreen interfaces should reflect technical capabilities of the system, ergonomics, cognitive psychology and human physiology.

Guidelines for touchscreen designs were first developed in the 2000s, based on early research and actual use of older systems, typically using infrared grids—which were highly dependent on the size of the user"s fingers. These guidelines are less relevant for the bulk of modern touch devices which use capacitive or resistive touch technology.

Much more important is the accuracy humans have in selecting targets with their finger or a pen stylus. The accuracy of user selection varies by position on the screen: users are most accurate at the center, less so at the left and right edges, and least accurate at the top edge and especially the bottom edge. The R95 accuracy (required radius for 95% target accuracy) varies from 7 mm (0.28 in) in the center to 12 mm (0.47 in) in the lower corners.

This user inaccuracy is a result of parallax, visual acuity and the speed of the feedback loop between the eyes and fingers. The precision of the human finger alone is much, much higher than this, so when assistive technologies are provided—such as on-screen magnifiers—users can move their finger (once in contact with the screen) with precision as small as 0.1 mm (0.004 in).

Users of handheld and portable touchscreen devices hold them in a variety of ways, and routinely change their method of holding and selection to suit the position and type of input. There are four basic types of handheld interaction:

Touchscreens are often used with haptic response systems. A common example of this technology is the vibratory feedback provided when a button on the touchscreen is tapped. Haptics are used to improve the user"s experience with touchscreens by providing simulated tactile feedback, and can be designed to react immediately, partly countering on-screen response latency. Research from the University of Glasgow (Brewster, Chohan, and Brown, 2007; and more recently Hogan) demonstrates that touchscreen users reduce input errors (by 20%), increase input speed (by 20%), and lower their cognitive load (by 40%) when touchscreens are combined with haptics or tactile feedback. On top of this, a study conducted in 2013 by Boston College explored the effects that touchscreens haptic stimulation had on triggering psychological ownership of a product. Their research concluded that a touchscreens ability to incorporate high amounts of haptic involvement resulted in customers feeling more endowment to the products they were designing or buying. The study also reported that consumers using a touchscreen were willing to accept a higher price point for the items they were purchasing.

Unsupported touchscreens are still fairly common in applications such as ATMs and data kiosks, but are not an issue as the typical user only engages for brief and widely spaced periods.

Touchscreens can suffer from the problem of fingerprints on the display. This can be mitigated by the use of materials with optical coatings designed to reduce the visible effects of fingerprint oils. Most modern smartphones have oleophobic coatings, which lessen the amount of oil residue. Another option is to install a matte-finish anti-glare screen protector, which creates a slightly roughened surface that does not easily retain smudges.

Touchscreens do not work most of the time when the user wears gloves. The thickness of the glove and the material they are made of play a significant role on that and the ability of a touchscreen to pick up a touch.

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Seems interesting UGUI. However for example for the controller ST7586S have any examples of LCD functions to associate with UGUI? If you have made and canst send to me …

Have you thought about how to implement screen rotation? I am wondering how to change to portrait from landscape on my display (at compile time, not run time)

However, i´m not a great GUI designer. I just have a RTOS project and i would like to disseminate the use of such a great tool for embedded software development. Even, i developed a demo based in your code using RTOS services. Doing that i realized a excessive CPU usage for the touch screen reading (like 10%). I just raised the I2C clock to 250khz, droping the CPU usage for less than 1%.

I"ve got a problem with the refresh rate. Some times a flicker line appear on the middle of the screen. The flicker will occurs rarely if I lower the PCLKto 16MHz, but it still appears.

Starting with your example of uGFX 3.0 on Stm32f429-Discovery (embd LCD removed) i have changed only screen dimensions to the ltdc.h in order to make it all work and so on it"s a really good result.

Can I use ugui with STM32F4-Discovery + ssd1963 fsmc module? I have ssd1963 library. I can run the screen but do not know how I could combine seamlessly with ugui. Can you help with this?Hi Mehmet,

We are using Tiny6410 stamp module. It is restricted to using only friendlyarm display. We need to interface resistive touchscreen display of 5 inch & 7 inch of our choice. Please give steps how we can use your library.

i really wonder about your gui. it is very simple to use. i want to draw a image on my lcd. i also done by using your library with given example image. now i want to convert image to header file. can you suggest any software to do that.Hi Arun, I think there is a conversion utility on the ST microelectronics page. I can’t remember the name, but I’m sure there is one. BR Achim

I tried, but I can not force to work my 240×128 display with T6963C controller . Could you please send me the code to this: 240×128 LCD | Driver: T6963C | Interface: 8080

I have a small display with no touchscreen. However I want to use windows with GUI buttons and use up/down buttons (physical buttons) to select GUI buttons on the screen (and use an enter button to simulate pressing a GUI button). Is it possible to do this with ugui, to select GUI buttons and generate GUI button clicks programmatically without toutchscreen?

I"ve set it up on an STM32L100RCT6 with an 128×64 glcd, and everything works like a charm, except the UG_DrawLine() function, which seems to always draw a falling line, no matter how the arguments are arranged