Install the libraryhttps://github.com/ThingPulse/esp8266-oled-ssd1306

  First, we need to include the Wire.h library, which is required for I2C communication with the OLED display. We also need to include the SSD1306.h library, which we will use to interact with the device.

#include <wire.h>
#include "SSD1306.h"

 Next, we need to declare an object of class SSD1306, which will provide the functions needed for drawing in the display. We will call this object to display.

  The constructor of the class mentioned below receives the I2C address of the device as the first parameter, which is 0x3c. As the second and third parameters, the constructor receives the number of SDA and SCL pins, respectively. In our example, as shown in the schematic, we use pins 21 and 22 of ESP32.

SSD1306 display(0x3c, 21, 22); 

 Now, in the setup function, we will initialize the display by calling the init method of the display object. This method takes no parameters and returns void.

display.init();

  Next we can start drawing on the display. For this simple example, we will draw a very simple "Hello World" message. For this, we can call the drawString method of the display object.

 This method receives the x and y coordinates as the first and second parameters, where the string will be drawn on the display, and as the third parameter, it receives the String with actual content.

display.drawString(0, 0, "Hello World");

 Finally, to send the content to the display for effective drawing, we need to call the display method on the object. This method does not receive any parameters.

display.display();

 Since we do not intend to change the display content, we may leave an empty Arduino loop function. As long as it is connected, the string we have just drawn will remain on the display. The final source code is shown below.

#include <Wire.h>
#include "SSD1306.h"

SSD1306 display(0x3c, 21, 22);

void setup() {
  display.init();

  display.setFont(ArialMT_Plain_24);
  display.drawString(0, 0, "Hello World");
  display.display();
}

void loop() {
 
}