china tft lcd ili9341 free sample

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.

As you can see, the module pins can be divided into four main categories, namely LCD command pins, LCD data pins, SD card pins and power pins, we don"t need to know the details of how these pins work because they will be implemented by the Arduino library.

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 best way to calibrate is to use a calibration sample program (with a library) or use a serial monitor to detect your errors. But for this project, calibration should not be a big issue due to the large size of the buttons, and I will also explain how to calibrate your LCD in the programming section below.

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 mentioned before, we need to calibrate the LCD to make it work properly, but don"t worry the values given here are almost universal. The variables TS_MINX, TS_MINY, TS_MAXX and TS_MAXY determine the calibration of the screen. If you feel that the calibration is not ideal, you can make a slight change.

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.

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.