How to create Class and Object on Arduino IDE

I want to do OOP (Object Oriented Programming) on Arduino. How to create Class and Object on Arduino IDE (version 1.x and 2.x)? For example, I want to create a class to control LED.

Answer

There are two ways to create and use Class on Arduino.

Create Class by making a library and include it into libraries on Arduino IDE
Create Class in the same folder with Arduino sketch

The rest of this will show how to create Class in the same folder with Arduino sketch.

Let's assump that we want to create a class, called LED, to do the following works:

Turn on a LED
Turn off a LED
Get the state of the LED

Let's do it step by step:

Open Arduino IDE, Create an Arduino sketch, called ArduinoGetStarted.com.ino. This code contains the setup() and loop() functions
Either click on the button just below the serial monitor icon and choose "New Tab", or press Ctrl+Shift+N.

Give file's name "LED.h" and click "OK" button

Copy the code and paste it to that file.

// LED.h #ifndef LED_h #define LED_h #include <Arduino.h> class LED { private: int ledPin; unsigned char ledState; public: LED(int pin); void turnON(); void turnOFF(); int getState(); }; #endif

Again, Either click on the button just below the serial monitor icon and choose "New Tab", or use Ctrl+Shift+N.
Give file's name "LED.cpp" and click "OK" button

Copy the code and paste it to that file.

// LED.cpp #include "LED.h" LED::LED(int pin) { ledPin = pin; ledState = LOW; pinMode(ledPin, OUTPUT); } void LED::turnON() { ledState = HIGH; digitalWrite(ledPin, ledState); } void LED::turnOFF() { ledState = LOW; digitalWrite(ledPin, ledState); } int LED::getState() { return ledState; }

Navigate to the ArduinoGetStarted.com.ino tab
Copy the code and paste it to that file.

// main code: ArduinoGetStarted.com.ino #include "LED.h" LED led1(2); // create a LED object that attach to pin 2 LED led2(3); // create a LED object that attach to pin 3 void setup() { Serial.begin(9600); } void loop() { led1.turnON(); led2.turnON(); Serial.print("LED 1 state: "); Serial.println(led1.getState()); Serial.print("LED 2 state: "); Serial.println(led2.getState()); delay(2000); led1.turnOFF(); led2.turnOFF(); Serial.print("LED 1 state: "); Serial.println(led1.getState()); Serial.print("LED 2 state: "); Serial.println(led2.getState()); delay(2000); }

Now you will see three files in three tab on Arduino IDE:

LED.h: This is a header file and it contains the class's declaration.
LED.cpp: This contains the class's definition (also called implementation).
ArduinoGetStarted.com.ino: This is main code of Arduino project. This file includes header file and creates objects of the class.

※ NOTE THAT:

Because the class files (LED.h and LED.cpp) are stored in the same folder as main sketch (ArduinoGetStarted.com.ino), You need to call #include "LED.h", not #include <LED.h>

Test the class and object by:

Upload the code to Arduino
See the result on Serial Monitor

COM6

Send

LED 1 state: 1 LED 2 state: 1 LED 1 state: 0 LED 2 state: 0 LED 1 state: 1 LED 2 state: 1 LED 1 state: 0 LED 2 state: 0

Autoscroll Show timestamp

Clear output

9600 baud

Newline

※ NOTE THAT:

The above code is a simple LED class. You can refer to our Arduino - LED library to learn more

See more references:

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