arduino tft lcd display loop example brands

In this article, you will learn how to use TFT LCDs by Arduino boards. From basic commands to professional designs and technics are all explained here.

In electronic’s projects, creating an interface between user and system is very important. This interface could be created by displaying useful data, a menu, and ease of access. A beautiful design is also very important.

There are several components to achieve this. LEDs,  7-segments, Character and Graphic displays, and full-color TFT LCDs. The right component for your projects depends on the amount of data to be displayed, type of user interaction, and processor capacity.

TFT LCD is a variant of a liquid-crystal display (LCD) that uses thin-film-transistor (TFT) technology to improve image qualities such as addressability and contrast. A TFT LCD is an active matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven LCDs with a few segments.

In Arduino-based projects, the processor frequency is low. So it is not possible to display complex, high definition images and high-speed motions. Therefore, full-color TFT LCDs can only be used to display simple data and commands.

In this article, we have used libraries and advanced technics to display data, charts, menu, etc. with a professional design. This can move your project presentation to a higher level.

In electronic’s projects, creating an interface between user and system is very important. This interface could be created by displaying useful data, a menu, and ease of access. A beautiful design is also very important.

There are several components to achieve this. LEDs,  7-segments, Character and Graphic displays, and full-color TFT LCDs. The right component for your projects depends on the amount of data to be displayed, type of user interaction, and processor capacity.

TFT LCD is a variant of a liquid-crystal display (LCD) that uses thin-film-transistor (TFT) technology to improve image qualities such as addressability and contrast. A TFT LCD is an active matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven LCDs with a few segments.

In Arduino-based projects, the processor frequency is low. So it is not possible to display complex, high definition images and high-speed motions. Therefore, full-color TFT LCDs can only be used to display simple data and commands.

In this article, we have used libraries and advanced technics to display data, charts, menu, etc. with a professional design. This can move your project presentation to a higher level.

Size of displays affects your project parameters. Bigger Display is not always better. if you want to display high-resolution images and signs, you should choose a big size display with higher resolution. But it decreases the speed of your processing, needs more space and also needs more current to run.

After choosing the right display, It’s time to choose the right controller. If you want to display characters, tests, numbers and static images and the speed of display is not important, the Atmega328 Arduino boards (such as Arduino UNO) are a proper choice. If the size of your code is big, The UNO board may not be enough. You can use Arduino Mega2560 instead. And if you want to show high resolution images and motions with high speed, you should use the ARM core Arduino boards such as Arduino DUE.

In electronics/computer hardware a display driver is usually a semiconductor integrated circuit (but may alternatively comprise a state machine made of discrete logic and other components) which provides an interface function between a microprocessor, microcontroller, ASIC or general-purpose peripheral interface and a particular type of display device, e.g. LCD, LED, OLED, ePaper, CRT, Vacuum fluorescent or Nixie.

The display driver will typically accept commands and data using an industry-standard general-purpose serial or parallel interface, such as TTL, CMOS, RS232, SPI, I2C, etc. and generate signals with suitable voltage, current, timing and demultiplexing to make the display show the desired text or image.

The LCDs manufacturers use different drivers in their products. Some of them are more popular and some of them are very unknown. To run your display easily, you should use Arduino LCDs libraries and add them to your code. Otherwise running the display may be very difficult. There are many free libraries you can find on the internet but the important point about the libraries is their compatibility with the LCD’s driver. The driver of your LCD must be known by your library. In this article, we use the Adafruit GFX library and MCUFRIEND KBV library and example codes. You can download them from the following links.

You must add the library and then upload the code. If it is the first time you run an Arduino board, don’t worry. Just follow these steps:Go to www.arduino.cc/en/Main/Software and download the software of your OS. Install the IDE software as instructed.

By these two functions, You can find out the resolution of the display. Just add them to the code and put the outputs in a uint16_t variable. Then read it from the Serial port by Serial.println(); . First add Serial.begin(9600); in setup().

First you should convert your image to hex code. Download the software from the following link. if you don’t want to change the settings of the software, you must invert the color of the image and make the image horizontally mirrored and rotate it 90 degrees counterclockwise. Now add it to the software and convert it. Open the exported file and copy the hex code to Arduino IDE. x and y are locations of the image. sx and sy are sizes of image. you can change the color of the image in the last input.

Upload your image and download the converted file that the UTFT libraries can process. Now copy the hex code to Arduino IDE. x and y are locations of the image. sx and sy are size of the image.

In this template, We converted a .jpg image to .c file and added to the code, wrote a string and used the fade code to display. Then we used scroll code to move the screen left. Download the .h file and add it to the folder of the Arduino sketch.

In this template, We used sin(); and cos(); functions to draw Arcs with our desired thickness and displayed number by text printing function. Then we converted an image to hex code and added them to the code and displayed the image by bitmap function. Then we used draw lines function to change the style of the image. Download the .h file and add it to the folder of the Arduino sketch.

In this template, We created a function which accepts numbers as input and displays them as a pie chart. We just use draw arc and filled circle functions.

In this template, We added a converted image to code and then used two black and white arcs to create the pointer of volumes.  Download the .h file and add it to the folder of the Arduino sketch.

In this template, We added a converted image and use the arc and print function to create this gauge.  Download the .h file and add it to folder of the Arduino sketch.

while (a < b) { Serial.println(a); j = 80 * (sin(PI * a / 2000)); i = 80 * (cos(PI * a / 2000)); j2 = 50 * (sin(PI * a / 2000)); i2 = 50 * (cos(PI * a / 2000)); tft.drawLine(i2 + 235, j2 + 169, i + 235, j + 169, tft.color565(0, 255, 255)); tft.fillRect(200, 153, 75, 33, 0x0000); tft.setTextSize(3); tft.setTextColor(0xffff); if ((a/20)>99)

while (b < a) { j = 80 * (sin(PI * a / 2000)); i = 80 * (cos(PI * a / 2000)); j2 = 50 * (sin(PI * a / 2000)); i2 = 50 * (cos(PI * a / 2000)); tft.drawLine(i2 + 235, j2 + 169, i + 235, j + 169, tft.color565(0, 0, 0)); tft.fillRect(200, 153, 75, 33, 0x0000); tft.setTextSize(3); tft.setTextColor(0xffff); if ((a/20)>99)

In this template, We display simple images one after each other very fast by bitmap function. So you can make your animation by this trick.  Download the .h file and add it to folder of the Arduino sketch.

In this template, We just display some images by RGBbitmap and bitmap functions. Just make a code for touchscreen and use this template.  Download the .h file and add it to folder of the Arduino sketch.

Hi guys, welcome to today’s tutorial. Today, we will look on how to use the 1.8″ ST7735  colored TFT display with Arduino. The past few tutorials have been focused on how to use the Nokia 5110 LCD display extensively but there will be a time when we will need to use a colored display or something bigger with additional features, that’s where the 1.8″ ST7735 TFT display comes in.

The ST7735 TFT display is a 1.8″ display with a resolution of 128×160 pixels and can display a wide range of colors ( full 18-bit color, 262,144 shades!). The display uses the SPI protocol for communication and has its own pixel-addressable frame buffer which means it can be used with all kinds of microcontroller and you only need 4 i/o pins. To complement the display, it also comes with an SD card slot on which colored bitmaps can be loaded and easily displayed on the screen.

The schematics for this project is fairly easy as the only thing we will be connecting to the Arduino is the display. Connect the display to the Arduino as shown in the schematics below.

Due to variation in display pin out from different manufacturers and for clarity, the pin connection between the Arduino and the TFT display is mapped out below:

We will use two libraries from Adafruit to help us easily communicate with the LCD. The libraries include the Adafruit GFX library which can be downloaded here and the Adafruit ST7735 Library which can be downloaded here.

We will use two example sketches to demonstrate the use of the ST7735 TFT display. The first example is the lightweight TFT Display text example sketch from the Adafruit TFT examples. It can be accessed by going to examples -> TFT -> Arduino -> TFTDisplaytext. This example displays the analog value of pin A0 on the display. It is one of the easiest examples that can be used to demonstrate the ability of this display.

The second example is the graphics test example from the more capable and heavier Adafruit ST7735 Arduino library. I will explain this particular example as it features the use of the display for diverse purposes including the display of text and “animated” graphics. With the Adafruit ST7735 library installed, this example can be accessed by going to examples -> Adafruit ST7735 library -> graphics test.

The first thing, as usual, is to include the libraries to be used after which we declare the pins on the Arduino to which our LCD pins are connected to. We also make a slight change to the code setting reset pin as pin 8 and DC pin as pin 9 to match our schematics.

Next, we create an object of the library with the pins to which the LCD is connected on the Arduino as parameters. There are two options for this, feel free to choose the most preferred.

Next, we move to the void setup function where we initialize the screen and call different test functions to display certain texts or images.  These functions can be edited to display what you want based on your project needs.

The complete code for this is available under the libraries example on the Arduino IDE. Don’t forget to change the DC and the RESET pin configuration in the code to match the schematics.

Uploading the code to the Arduino board brings a flash of different shapes and text with different colors on the display. I captured one and its shown in the image below.

That’s it for this tutorial guys, what interesting thing are you going to build with this display? Let’s get the conversation started. Feel free to reach me via the comment section if you have any questions as regards this project.

Touchscreen displays are everywhere! Phones, tablets, self-serve kiosks, bank machines and thousands of other devices we interact with make use of touchscreen displays to provide an intuitive user interface.

Today we will learn how touchscreens work, and how to use a common inexpensive resistive touchscreen shield for the Arduino.  Future videos and articles will cover capacitive touchscreens, as well as a touchscreen HAT for the Raspberry Pi.

Eric A Johnson, a researcher at the Royal Radar Establishment in Malvern UK is credited for describing and then prototyping the first practical touchscreen. HIs device was a capacitive touchscreen, and it’s first commercial use was on air traffic control screens. However, the touchscreens used then were not transparent, instead, they were mounted on the frame of the CRT display.

In 1972, a group at the University of Illinois filed for a patent on an optical touchscreen. This device used a 16×16 array of LEDs and phototransistors, mounted on a frame around a CRT display. Placing your finger, or another solid object, on the screen would break two of the light beams, this was used to determine the position and respond accordingly.

The first commercial product to use a touchscreen was a point-of-sale terminal developed by Atari and displayed at the 1986 COMDEX expo in Las Vegas. The next year Casio launched theCasio PB-1000 pocket computerwith a touchscreen consisting of a simple 4×4 matrix.

This is the most inexpensive method of designing a resistive touchscreen. The touchscreen display that we will be working with today uses this arrangement.

Capacitive touchscreens are actually older technology than resistive displays.  They are commonly used in phones and tablets, so you’re probably familiar with them.

The module we will be experimenting with today is a very common Arduino Shield, which is rebranded by many manufacturers. You can easily find these on Amazon, eBay or at your local electronics shop.

You can also just use the shield as an LCD display and ignore the two other components, however, if you intend on doing that it would be cheaper just to buy an LCD display without any touchscreen features.

This is a TFT orThin Film Transistordevice that uses liquid crystals to produce a display.  These displays can produce a large number of colors with a pretty decent resolution.

You do need to be looking directly at the display for best color accuracy, as most of these inexpensive LCD displays suffer from distortion and “parallax error” when viewed from the side. But as the most common application for a device like this is as a User Interface (UI) this shouldn’t be a problem.

This shield uses a 4-wire analog resistive touchscreen, as described earlier.  Two of the wires (one X and one Y) are connected to a couple of the analog inputs on the Arduino. The analog inputs are required as the voltage levels need to be measured to determine the position of the object touching the screen.

The microSD card socket is a convenience, it’s normally used for holding images for the display but it can also be used for program storage.  This can be handy for holding things like calibration settings and favorite selections.

You should note that the microSD card uses the SPI interface and is wired for the Arduino Uno. While the rest of the shield will function with an Arduino Mega 2560, the SPI connections on the Mega are different, so the microSD card will not work.

The last paragraph regarding the microSD card may make you think that an Arduino Uno is the best choice for the Touchscreen Display Shield.  And it you require the microSD card then it probably is a good choice.

But using an Arduino Uno with this shield does have one big disadvantage – a limited number of free I/O pins.  In fact there are only three pins left over once the card has been plugged in:

If your product is self-contained and doesn’t need many (or any) I/O pins then you’ll be fine. But if you need more pins to interface with then an Arduino Mega 2560 is a much better choice. It has a lot of additional analog and digital pins.

So if you don’t require the microSD card, or are willing to hook up a separate microSD card, then the Arduino Mega 2560 is a better choice for most applications.

As there are three devices on the shield you will need libraries for each of the ones you want to use.  TheSD Libraryis already installed in your Arduino IDE, so you will just need libraries for the display and touchscreen.

For the LCD you will have a lot of choices in libraries. Most of these shields come with a CD ROM with some sketches and libraries, so you can use the LCD libraries there. Bear in mind however that code on these CD ROMs tends to be a little dated, you may have better lick on the vendors website.

This useful resource contains code, libraries and datasheets for a wealth of LCD displays, both touchscreen and non-touchscreen. You’ll also find code for some common OLED displays as well.

I ran my touchscreen through all of the code samples I obtained from the LCD Wiki. It’s an interesting exercise, and by examining the sketch for each demo you can learn a lot about programming the display.

The first example is a very simple color “sweep” test. Navigate to theExample_01_Simple_testfolder and open the folder for your Arduino controller.  Navigate down until you find the “ino” file and load it.

This test does not make use of any of the extra libraries, it drives the LCD directly. It is only a test of the LCD display, it does not make use of the touchscreen membrane.

You’ll find this example in theExample_02_clear_screenfolder, the sameclear_Screen.inoexample is used for both the Uno and Mega so there are no separate folders.

This example does use the custom libraries, and is a very good way to learn how to use them.  You’ll note that theLCDWIKI_GUI.hlibrary is loaded, which is the graphics library for the LCD display.

Another library, LCDWIKI_KBV.h, is loaded as well. This is a hardware-specific “helper” library that provides an interface to the actual hardware for the other libraries.

When you run this example the results will be similar to the first one, a series of colors will sweep across the screen. In this case the colors are different, and they vary in speed.

A look at the loop will show how this is done. TheLCDWIKI_GUI.hlibrary has a “Fill_Screen” method that fills the screen with an RGB color. You can specify the color in both hexadecimal or decimal format, the example illustrates both ways.

The example itself is in a folder labeled “Example_03_colligate_test” and the code itself is in the colligate_test.ino file. I suspect a translation error resulted in the name!

This sketch uses a number of functions from theLCDWIKI_GUI.hlibrary, along with some custom functions to draw geometric shapes. It then displays a cycle of graphs, shapes, and patterns on the LCD display.

One way in which this sketch differs is that most of the graphics routines are executed in the Setup function, so they only run once. The loop then displays some text with a selection of colors and fonts. The orientation is changed as it cycles through the loop.

This example makes use of a second file that contains fonts. The Display Scroll sketch illustrates a number of different methods of scrolling characters, in different fonts, colors and even languages.

One interesting thing about this test is that it illustrates how to display text in different “aspects”, Portrait and Landscape, Right side up and Reversed.

Unlike the previous examples that put the text in with a number of graphics, this example is a pretty simple one with just a block of text in different sizes and colors.  This makes it very simple to understand how the text is positioned on the display.

The result of running the sketch is the display screen fills with rows of hexadecimal values while the background alternates between blue and black and the orientation (or “aspect”) changes.  If you stand back to see the “big picture” you’ll note that the color values form “number patterns”.

The Display Phone Call sketch draws a mockup telephone keypad. Pressing one of the keys will display the result on a line of text at the top.  There is also a key to delete your entries, as well as ones to send and disconnect the call – the latter two are “dummy” functions of course as it’s only a demo.

In addition to the graphics and “helper” libraries that have been used in the previous examples this sketch also uses theTouchScreenlibrary to read screen interaction.  This was one of the libraries included in the original ZIP file.

As its name would imply, this sketch displays a bitmap image on the display. The images need to be placed onto the root of a microSD card, which in turn is plugged into the socket on the display shield.

Note that this demo will only work on the Arduino Uno, as the microSD card uses the SPI bus and is wired to the Arduino Uno SPI port. The Arduino Mega 2560 board uses different pins for SPI.

The images will show off the display resolution, which is reasonably impressive. You’ll also note that to see them at their best, you need to be directly in front of the display, viewing the display at an angle causes the display to distort colors.

Another thing you will notice is the speed at which the images draw, which is not particularly impressive. The clock speed of the Arduino has a lot to do with this, as does the method used to extract each individual pixel from the image.

This example draws some small “switches” on the display. The switches are active and respond to touch.  There are slide switches, a push button, some radio buttons and some text-based expandable menus to test with.

The Touch Pen example is actually a pretty decent little drawing application. You can draw whatever you want on the main screen area. A set of buttons allow you to set the stylus color and pen width.

While the sample code is a bit difficult to follow it’s worth the effort, as it shows you how to create a dynamic menu system. Touching the stylus color button, for example, will open a new menu to select colors.  This is a handy technique that you’ll need to know when developing your own user interfaces.

After calibration, the sketch will display a number of calibration values for the resistive touchscreen. These values can be used in your future sketches to make the touchscreen more accurate.

The examples are a great way to demonstrate the capabilities of your touchscreen. But to really put your interface to work you’ll need to write your own interface code.

Writing a touchscreen interface can be challenging. I would suggest that you start by modifying one of the example codes, one that is closest to your desired interface.

For my experiment, I will be using an Arduino Mega 2560 to drive three LEDs. I used a Red, Green and Blue LED but really any colors will work – I just wanted my LED colors to match my button colors.

The digital I/O connector at the back of the Mega is still accessible even when the touchscreen display shield is installed, so I used three of those connections for the LEDs. I hooked up each LED anode through a 220-ohm dropping resistor and connected them as follows:

The sketch is based upon the telephone keypad sketch. I modified it to eliminate the other functions and just display three buttons.  Then I added code to toggle the LEDs.

TheAdafruit GFX Libraryis a comprehensive graphics library that can be used in a variety of display applications.  It is a “core library”, meaning that it is called by other Adafruit libraries.

TheAdafruit TFTLCD Libraryis used. It uses the previous library to provide an easy method of drawing on the LCD display.  It works with LCD displays that use driver chips like the ILI9325 and ILI9328.

TheTouchScreenlibrary comes in the code that you downloaded from the LCD Wiki or from the CD ROM included with your touchscreen shield.  As its name implies it is used to interface with the touchscreen.

TheMCUFRIEND_kbvlibrary is also included in the software you obtained for your display shield. It takes care of supplying the correct hardware information for your display shield to the other libraries.

Next, we define some touchscreen parameters. You can ‘fine-tune” your code here by using parameters from your own display, which you can obtain from the Calibration Sketch we ran from the sample code.  Otherwise, just use the values here and you should be fine.

Next, we reset the display and try to identify it. This will run through a list of display chip drivers in the MCUFRIEND_kbv library and will attempt to select the correct one.

Now, still in the Setup, we set up the LCD display rotation and fill the background in black. Next step is to draw our buttons. Once we are done that the Setup is finished, and our screen should be displaying the three buttons on a black background.

The loop is where we will be monitoring the screen for keypresses. If we get one, and if its position corresponds to a button location, then we need to toggle the correct LED.

We start by triggering the touchscreen, which is done by toggling pin 13 on the Arduino high. If something is touching the screen we read it and assign it to a TSPoint object named “p”.

We then need to reset the pin modes for two of the touchscreen pins back to outputs. This is done as these pins get shared with other LCD display functions and get set as inputs temporarily.

Load the code into your Arduino IDE and upload it to your Arduino Mega 2560. Make sure you have the correct processor-type set in your Arduino IDE, especially if you are used to working with the Uno!

This is a pretty simple demo but it does illustrate how to create a simple IDE. You can expand upon it to add more buttons, or to change the button colors or shapes. And, of course, you don’t have to light LEDs with your buttons, they can control anything that you can connect to your Arduino.

Touchscreen interfaces are used in a number of products, and now you can design your own devices using them. They can really make for an intuitive and advanced display and will give your project a very professional “look and feel” if done correctly.

This is not the only time we will look at touchscreen displays. Next time we’ll examine a capacitive touchscreen and we’ll explore the Adafruit Graphics libraries further to create some very fancy displays with controls and indicators.

Let"s learn how to use a touchscreen with the Arduino. We will examine the different types of touchscreens and will then create a simple interface using an inexpensive Arduino touchscreen shield.

If I write any draw-function in the loop the screen turns white. I figured that this is because the screen needs some time to build up. So I added a delay(1000). But then the screen flashes every second wich is obviously also not what I want.

The next weired thing is that the program stops working when I draw once the display is touched. In the code below I have three draw-functions. Two of them are working one is not. (see comments)

Update: I stoped the display from flashing by letting the touched event only happen once when the display is touched. But I am still having the problem that nothing is drawn...

The display is driven by a ST7735R controller ( ST7735R-specifications.pdf (2.1 MB) ), can be used in a “slow” and a “fast” write mode, and is 3.3V/5V compatible.

Adafruit_ST7735 is the library we need to pair with the graphics library for hardware specific functions of the ST7735 TFT Display/SD-Card controller.

In the file dialog select the downloaded ZIP file and your library will be installed automatically. This will automatically install the library for you (requires Arduino 1.0.5 or newer). Restarting your Arduino software is recommended as it will make the examples visible in the examples menu.

The easiest way to remedy this is by extracting the GitHub ZIP file. Place the files in a directory with the proper library name (Adafruit_GFX, Adafruit_ST7735 or SD) and zip the folder (Adafruit_GFX, Adafruit_ST7735.zip, SD.zip). Now the Arduino software can read and install the library automatically for you.

Basically, besides the obvious backlight, we tell the controller first what we are talking to with the CS pins. CS(TFT) selects data to be for the Display, and CS(SD) to set data for the SD-Card. Data is written to the selected device through SDA (display) or MOSI (SD-Card). Data is read from the SD-Card through MISO.

So when using both display and SD-Card, and utilizing the Adafruit libraries with a SainSmart display, you will need to connect SDA to MOSI, and SCL to SCLK.

As mentioned before, the display has a SLOW and a FAST mode, each serving it’s own purpose. Do some experiments with both speeds to determine which one works for your application. Of course, the need of particular Arduino pins plays a role in this decision as well …

Note: Adafruit displays can have different colored tabs on the transparent label on your display. You might need to adapt your code if your display shows a little odd shift. I noticed that my SainSmart display (gree tab) behaves best with the code for the black tab – try them out to see which one works best for yours.

Low Speed display is about 1/5 of the speed of High Speed display, which makes it only suitable for particular purposes, but at least the SPI pins of the Arduino are available.

After connecting the display in Low Speed configuration, you can load the first example from the Arduino Software (“File” “Example” “Adafruit_ST7735” –  recommend starting with the “graphictest“).

Below the code parts for a LOW SPEED display (pay attention to the highlighted lines) – keep in mind that the names of the pins in the code are based on the Adafruit display:

You can name your BMP file “parrot.bmp” or modify the Sketch to have the proper filename (in “spitftbitmap” line 70, and in “soft_spitftbitmap” line 74).

#define SD_CS 4 // Chip select line for SD card#define TFT_CS 10 // Chip select line for TFT display#define TFT_DC 9 // Data/command line for TFT#define TFT_RST 8 // Reset line for TFT (or connect to +5V)

#define SD_CS 4 // Chip select line for SD card#define TFT_CS 10 // Chip select line for TFT display#define TFT_DC 9 // Data/command line for TFT#define TFT_RST 8 // Reset line for TFT (or connect to +5V)

To use this in your Arduino Sketch: The first 2 characters represent RED, the second set of two characters is for GREEN and the last 2 characters represent BLUE. Add ‘0x’ in front of each of these hex values when using them (‘0x’ designates a hexadecimal value).

This function is used to indicate what corner of your display is considered (0,0), which in essence rotates the coordinate system 0, 90, 180 or 270 degrees.

However, if your application needs your screen sideways, then you’d want to rotate the screen 90 degrees, effectively changing the display from a 128×160 pixel (WxH) screen to a 160×128 pixel display. Valid values are: 0 (0 degrees), 1 (90 degrees), 2 (180 degrees) and 3 (270 degrees).

Based on these functions, I did create a little demo to show what these functions do. Either download the file or just copy the code and paste it into an empty Arduino Sketch.

tft.print("Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur adipiscing ante sed nibh tincidunt feugiat. Maecenas enim massa, fringilla sed malesuada et, malesuada sit amet turpis. Sed porttitor neque ut ante pretium vitae malesuada nunc bibendum. Nullam aliquet ultrices massa eu hendrerit. Ut sed nisi lorem. In vestibulum purus a tortor imperdiet posuere. ");

Recently, I had the idea to make a digital picture frame—one of these kinds which load images from SD cards and show each image for some time. I was remembering myself that I already own a small TFT display, the KMR-1.8 SPI, that works out of the box with an Arduino Uno. When I digged up my KMR-1.8 SPI, I realized that it has also an in-built SD card reader. Moreover, I looked up the Internet and found ready-to-use libraries for the in-built SD card reader as well as showing images on the TFT display. For these reasons, I thought making such an digital picture frame will turn out very easy.

When I started to implement my first lines of codes and started to connect my Arduino Uno to the KMR-1.8 SPI, I ran into two major problems. First, the colors of my image file did not match to the colors displayed by the KMR-1.8 (red and blue were interchanged). Second, my first prototypes stopped to work after about 5 minutes. The application started to freeze and showed the same image forever instead of displaying the next image after a chosen time.

I did some research on the Internet and I found out that many people ran into similar problems. The second problem seemed to be caused by some memory leaks in the code. Nevertheless, I did not came across any example code that worked out of the box for my setup. Therefore, I want to share how I made it work.

There exists various versions of so-called “1.8 TFT displays” from different manufacturers. Not all of them are 100% compatible to each other. Therefore, if you own a TFT display and want to use my tutorial to make it work, please check if your TFT display really matches the version I used in this tutorial:

The source code relies on three header files (and libraries): SPI.h (Link), SD.h (Link) and TFT.h (Link). Please make sure that all of them are correctly installed before trying out my source code (In Arduino IDE: Tools -> Manage Libraries…).

In the introduction of this blog post, I mentioned that I came across two major problems: the colors red and blue were interchanged and my early Arduino programs started to freeze after some time. Luckily, I was able to fix all issues. The following source code works perfect on my setup. My “digital picture frame” does not require to be restarted after some time (my long-term test lasted about two weeks—and no restart was necessary).

I overcame the first problem by not using the default initialization method (“TFTscreen.begin();”) of the TFT library. Instead, I looked up whats inside the “begin”-method. I found a method called “initR” which has a parameter that allows to perform the initialization for a specific chip. Here, the parameter value “INITR_BLACKTAB” worked for me as the colors were then shown correctly. In addition, I call the method “setRotation” with parameter value “1” in order to be conform to the default initialization method. In the end, the code for the setting up the TFT library object looks like this:// ...

The code looks for image files (*.BMP) on the SD card and shows each image for 60 seconds. You can change the display time by setting “DELAY_IMAGE_SWAP” to a new value.

In this Arduino touch screen tutorial we will learn how to use TFT LCD Touch Screen with Arduino. You can watch the following video or read the written tutorial below.

For this tutorial I composed three examples. The first example is distance measurement using ultrasonic sensor. The output from the sensor, or the distance is printed on the screen and using the touch screen we can select the units, either centimeters or inches.

The next example is controlling an RGB LED using these three RGB sliders. For example if we start to slide the blue slider, the LED will light up in blue and increase the light as we would go to the maximum value. So the sliders can move from 0 to 255 and with their combination we can set any color to the RGB LED,  but just keep in mind that the LED cannot represent the colors that much accurate.

The third example is a game. Actually it’s a replica of the popular Flappy Bird game for smartphones. We can play the game using the push button or even using the touch screen itself.

As an example I am using a 3.2” TFT Touch Screen in a combination with a TFT LCD Arduino Mega Shield. We need a shield because the TFT Touch screen works at 3.3V and the Arduino Mega outputs are 5 V. For the first example I have the HC-SR04 ultrasonic sensor, then for the second example an RGB LED with three resistors and a push button for the game example. Also I had to make a custom made pin header like this, by soldering pin headers and bend on of them so I could insert them in between the Arduino Board and the TFT Shield.

Here’s the circuit schematic. We will use the GND pin, the digital pins from 8 to 13, as well as the pin number 14. As the 5V pins are already used by the TFT Screen I will use the pin number 13 as VCC, by setting it right away high in the setup section of code.

I will use the UTFT and URTouch libraries made by Henning Karlsen. Here I would like to say thanks to him for the incredible work he has done. The libraries enable really easy use of the TFT Screens, and they work with many different TFT screens sizes, shields and controllers. You can download these libraries from his website, RinkyDinkElectronics.com and also find a lot of demo examples and detailed documentation of how to use them.

After we include the libraries we need to create UTFT and URTouch objects. The parameters of these objects depends on the model of the TFT Screen and Shield and these details can be also found in the documentation of the libraries.

So now I will explain how we can make the home screen of the program. With the setBackColor() function we need to set the background color of the text, black one in our case. Then we need to set the color to white, set the big font and using the print() function, we will print the string “Arduino TFT Tutorial” at the center of the screen and 10 pixels  down the Y – Axis of the screen. Next we will set the color to red and draw the red line below the text. After that we need to set the color back to white, and print the two other strings, “by HowToMechatronics.com” using the small font and “Select Example” using the big font.

Now we need to make the buttons functional so that when we press them they would send us to the appropriate example. In the setup section we set the character ‘0’ to the currentPage variable, which will indicate that we are at the home screen. So if that’s true, and if we press on the screen this if statement would become true and using these lines here we will get the X and Y coordinates where the screen has been pressed. If that’s the area that covers the first button we will call the drawDistanceSensor() custom function which will activate the distance sensor example. Also we will set the character ‘1’ to the variable currentPage which will indicate that we are at the first example. The drawFrame() custom function is used for highlighting the button when it’s pressed. The same procedure goes for the two other buttons.

drawDistanceSensor(); // It is called only once, because in the next iteration of the loop, this above if statement will be false so this funtion won"t be called. This function will draw the graphics of the first example.

getDistance(); // Gets distance from the sensor and this function is repeatedly called while we are at the first example in order to print the lasest results from the distance sensor

So the drawDistanceSensor() custom function needs to be called only once when the button is pressed in order to draw all the graphics of this example in similar way as we described for the home screen. However, the getDistance() custom function needs to be called repeatedly in order to print the latest results of the distance measured by the sensor.

Here’s that function which uses the ultrasonic sensor to calculate the distance and print the values with SevenSegNum font in green color, either in centimeters or inches. If you need more details how the ultrasonic sensor works you can check my particular tutorialfor that. Back in the loop section we can see what happens when we press the select unit buttons as well as the back button.

Ok next is the RGB LED Control example. If we press the second button, the drawLedControl() custom function will be called only once for drawing the graphic of that example and the setLedColor() custom function will be repeatedly called. In this function we use the touch screen to set the values of the 3 sliders from 0 to 255. With the if statements we confine the area of each slider and get the X value of the slider. So the values of the X coordinate of each slider are from 38 to 310 pixels and we need to map these values into values from 0 to 255 which will be used as a PWM signal for lighting up the LED. If you need more details how the RGB LED works you can check my particular tutorialfor that. The rest of the code in this custom function is for drawing the sliders. Back in the loop section we only have the back button which also turns off the LED when pressed.

In order the code to work and compile you will have to include an addition “.c” file in the same directory with the Arduino sketch. This file is for the third game example and it’s a bitmap of the bird. For more details how this part of the code work  you can check my particular tutorial. Here you can download that file:

drawDistanceSensor(); // It is called only once, because in the next iteration of the loop, this above if statement will be false so this funtion won"t be called. This function will draw the graphics of the first example.

getDistance(); // Gets distance from the sensor and this function is repeatedly called while we are at the first example in order to print the lasest results from the distance sensor

I picked up the project again today and de-soldered my SAMD51 T4 clone pcb as I need speed! The T4 would have been perfect, so tried a few code changes, got the screen running in the setup function (static text etc), but as soon as it enters the loop(), you guessed it....white screen. Its as if the t4 is too fast on spi or something, but I have changed the clock speeds down to 5mhz and yield the same results...

To confirm, I had the T4 intermittently working on both the adafruit ili9341 library and the optimised ili9341_t3. I"ve been through 3 T4s and I have 5 different ILI934 displays. (all give the same results, pull ups, no pullups, removed sd circuitry, ran the T4 at 5v I"ve tried it all!)