china ili9341 tft display free sample
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.
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.
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Arduino development boards always help us to build a project easily and make it look more attractive. Programming an LCD with touch functionality may sound like a complicated task, but it can be made very easy by using Arduino libraries and extension modules. In this project, we will use a 3.5" Arduino TFT LCD to build an Arduino touchscreen calculator that can perform all basic calculations such as addition, subtraction, division, and multiplication.
Before we dive into the project, it is important to understand how this 3.5" TFT LCD module works and the model number used. Let"s take a look at the pinout of this 3.5" TFT LCD module.
You can also find an SD card slot on the bottom of the module shown above. This slot can be used to load an SD card with bmp image files, which can be displayed on our TFT LCD screen using the Arduino program.
Another important thing to keep in mind is your interface IC. there are many types of TFT modules on the market from Adafruit TFT LCD modules to cheap Chinese clones. A program that fits an Adafruit expansion board may not be the same for a Chinese expansion board. Therefore, it is very important to know which type of LCD LCD you are holding. This detail must be obtained from the supplier. If you have a cheap clone like mine, then it most likely uses driver IC ili9341. You can follow the official Arduino tutorial to try some basic example programs to get familiar with this LCD.
If you intend to use the touch screen function of a TFT LCD module, it must be calibrated to work properly. An LCD screen that is not calibrated is unlikely to work properly; for example, you may touch in one place and the TFT may think it is touching somewhere else. These calibration results are not the same for all boards, so you will have to do this work yourself.
The 3.5" TFT LCD is a great Arduino expansion board. You can push the LCD directly onto the top of the Arduino Uno and have it match the pins perfectly and slide them in. However, for safety reasons, the programming terminals of the Arduino UNO must use small insulating tape in case the terminals come into contact with your TFT LCD screen. the LCD assembled to the UNO development board looks like the following.
We use the SPFD5408 library to ensure that the arduino calculator code works properly. This is a modified Adafruit library that works seamlessly with our LCD TFT module. You can view the full program at the end of this article.
As we know, TFT LCD screens can display many colors, all of which must be entered as hexadecimal values. To make it more readable, we assign these values to a variable as shown below.
Okay, now we can move on to the programming part. This program involves three parts. One is to create a user interface for the calculator using buttons and displays. Then, detect the buttons based on user touch and finally calculate the results and display them. Let"s go through them one by one.
Here you can get creative to design the user interface of the calculator. I simply made the basic layout of the calculator with 16 buttons and a display unit. You must build the design as if you were drawing something on an MS drawing board. The added libraries will allow you to draw lines, rectangles, circles, characters, strings and more in any of the preferred colors. You can learn about the available features from this article.
Another challenging task is to detect the user"s touch. Every time the user touches something, we are able to know the X and Y position of the pixel he touched. This value can be displayed on the serial monitor using println, as shown below.
The final step is to calculate the results and display them on the TFT LCD screen. The arduino calculator can only perform two numeric operations. These two numbers are named as variables "Num1" and "Num2". The variable "Number" is given and taken from Num1 and Num2, and the result is obtained.
The process of working with this Arduino touch screen calculator is very simple. You need to upload the following code to the Arduino development board and then power it up. At this point, a calculator will be displayed on the LCD screen.
To download. click the DOWNLOADS button in the top right corner, rename the uncompressed folder Adafruit_ILI9341. Check that the Adafruit_ILI9341 folder contains Adafruit_ILI9341.cpp and Adafruit_ILI9341.
Place the Adafruit_ILI9341 library folder your arduinosketchfolder/libraries/ folder. You may need to create the libraries subfolder if its your first library. Restart the IDE