HOW TO WRITE YOUR OWN ARDUINO LIBRARY?

In the previous tutorial, we’ve met with 7 segment displays. Among everything else, we’ve learned why libraries are useful. Now is the time to write our own. We will sort out this lesson in files that need to be made to make the library functional and transparent.

The thing we want, and will do, are functions that write numbers from 0 to 9, a function that will shut down all segments on the display and a function that will turn the point on and off. Let’s go…

The header file is saved with an .h extension, it’s one of the two necessary files to make the library function. Bearing in mind that Arduino doesn’t do that by itself, here we will define everything that we use in a library. We create a class that we can call in later on in Arduino IDE with all the variables and functions that we want to make available to the user (public)  and those internal ones that we will use to make the library functional (private).

What is a class? If you haven’t met with the term class by now, it’s basically a group of all functions and variables for a certain object. For example, let’s take a male human as an object. Every male has or hasn’t got certain characteristics like IQ, height, mass, height or moustaches. Looking from the programmers’ point of view, IQ is a whole number variable int, height and mass can be float, and moustaches which you either have or you don’t are going to be boolean.

With all that behind us,  let’s get back to creating a library. Open your favorite text editor and let’s get into it:

Source file is a part where we store all of our code/logic, and it’s written in C++ language. Even tho we’ve already explained the logic we want to write, feel free to take a peak in the 7 segment displays tutorial and remind yourself how to work with that. For starters we need to include Arduino.h and  Segment.h  which we  have just created. Again, ofcourse we write in a text editor.

Keywords is a  .txt file that allows Arduino IDE to recognize keywords from our library and changes their color in the editor to make it easier to work with. It would look something like this:

If we want the example of libraries used to appear in Arduino IDE File-Examples we need to create a subfolder called examples. This is how it will look like in Windows OS:

In subfolder examples, we will save examples of libraries’ usage. You can write it in Arduino IDE software, and as an example, we will write a countdown on the display.