I2C OLED Module En

Overview

The Arduino OLED module is a display module with a small size and high resolution, suitable for various projects. Based on OLED (Organic Light Emitting Diode) technology, it provides excellent color and contrast.

OLED Operating Principle

Organic Material: OLED contains a thin layer of organic materials that emit light when an electric current passes through. Organic compounds have the property of emitting light when stimulated electrically. Electrodes: The OLED panel typically consists of two electrodes (anode and cathode). When electricity flows, the organic material releases electrons, and these electrons combine with holes to generate light.

SSD1306

The SSD1306 is a driver IC (integrated circuit) used to control OLED displays.

It contains 1KB of dedicated RAM for graphic display (GDDRAM), which is used to store the bit patterns to be displayed.

List	Explanation
Memory capacity	1KB (8192bit)
Number of Page	8 page (Page 0-7)
Number of lines arranged vertically	128 vertical lines (vertical line 0-127)
Bit Information	8 bits per vertical line (bits 0-7)
Calculation	8 pages x 128 vertical lines x 8 bits = 8192 bits = 1024 bytes (1KB)

Specification

List	Explanation
Display Size	Various sizes such as 0.91inch, 0.96inch, 1.3inch, 2.42inch
Resolution	128x64 pixels or 128x32 pixels
Display Type	OLED (Organic Light Emitting Diode)
Color	Black and White (White or Blue)
Interface	I2C (2 pins)
Voltage	3.3V ~ 5V
Power Consumption	Standby Power: About 0.1mA, Maximum Power: About 20mA

Application Examples

Circuit Configuration

OLED module pin	Arduino Uno/Nano	Arduino Mega
VCC	5V or 3.3V	5V or 3.3V
GND	GND	GND
SCL	A5	21
SDA	A4	22

Device Address Verification

This is the code used to find the address of devices connected to the I2C bus.

Before running the examples introduced below, please run the I2C Scanner first to check the address of the module.

#include <Wire.h>

void setup() {
  Serial.begin(9600);
  Wire.begin();
  Serial.println("I2C Scanner Start...");
}

void loop() {
  byte error, address;
  int nDevices = 0;

  Serial.println("I2C Device Scanning...");

  for (address = 1; address < 127; address++) {
    // Attempting to connect to the I2C device
    Wire.beginTransmission(address);
    error = Wire.endTransmission();

    if (error == 0) {
      Serial.print("Device found! Address: 0x");
      if (address < 16) {
        Serial.print("0");
      }
      Serial.print(address, HEX);
      Serial.println();
      nDevices++;
    } else if (error == 4) {
      Serial.print("Address 0x");
      Serial.print(address, HEX);
      Serial.println("error occurred!");
    }
  }

  if (nDevices == 0) {
    Serial.println("No I2C device found.");
  } else {
    Serial.println("Device scanning complete.");
  }

  delay(5000); // Wait for 5 seconds before scanning again.
}

실행 결과

Library

Please use the Adafruit SSD1306 library.

When installing SSD1306, please also click INSTALL ALL to install the required Adafruit BusIO and Adafruit GFX Library together.

1. Library Default Examples

Click on File - Examples - Adafruit SSD1306 - ssd1306_128x64 i2c to open the example.

Please change the Address part in the example code to the device address confirmed earlier with the I2C Scanner.

2. Text Output

This is an example of printing simple text.

I used a 0.91-inch OLED, and since this module has a resolution of 128 x 32 pixels, I changed the 6th line SCREEN_HEIGHT from 64 to 32.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128  // OLED width
#define SCREEN_HEIGHT 32   // OLED height

// I2C address of the OLED module (typically 0x3D or 0x3C)
#define OLED_ADDR 0x3C 

// Create Adafruit_SSD1306 object
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  // OLED Initialization
  display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR);
  display.clearDisplay(); // Clear the screen
  display.setTextSize(1); // Set text size
  display.setTextColor(SSD1306_WHITE); // Set text color
  display.setCursor(0, 0); // Set cursor position
  display.println("GONGZIPSA"); // Print text
  display.setCursor(0, 10); // Set cursor position
  display.println("ArduWiki"); // Print text
  display.display(); // Display on the screen
}

void loop() {
}

The roles of the used functions are as follows.

Functions	Explanation
begin()	Initializes the OLED display. Sets the I2C address and resolution.
clearDisplay()	Clears the current content of the display. Initializes the screen.
setTextSize(size)	Sets the size of the text to be displayed. The size indicates the scale. (e.g., 1, 2, etc.)
setTextColor(color)	Sets the color of the text. Typically, SSD1306_WHITE and SSD1306_BLACK are used.
setCursor(x, y)	Sets the position where the text will be displayed. x is the horizontal position, and y is the vertical position. (0, 0) is the top-left corner, and as x increases, it moves to the right, while increasing y moves it downward.
println("Contents")	Sets the content to be displayed.
display()	Outputs the content stored in the buffer to the OLED display.

Execution Result

3. Simple Shape Output

This is an example of outputting simple shapes such as rectangles, triangles, and circles.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_ADDR 0x3C 

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR);
  display.clearDisplay(); // Clear the screen
  display.drawTriangle(10, 10, 40, 30, 10, 30, WHITE); // Draw a small triangle
  display.drawRect(50, 10, 30, 20, WHITE); // Draw a rectangle
  display.fillRect(90, 10, 30, 20, WHITE); // Draw a filled rectangle
  display.drawCircle(25, 50, 13, WHITE); // Draw a circle
  display.drawRoundRect(50, 40, 30, 20, 7, WHITE); // Draw a rounded rectangle
  display.fillRoundRect(90, 40, 30, 20, 7, WHITE); // Draw a filled rounded rectangle
  display.display(); // Display the shapes
}

void loop() {
  
}

The functions related to shapes are as follows:

Functions	Explanation
drawLine(x1, y1, x2, y2, color)	Draws a line connecting two points.
drawRect(x, y, width, height, color)	Draws an empty rectangle.
fillRect(x, y, width, height, color)	Draws a filled rectangle.
drawCircle(x, y, radius, color)	Draws an empty circle.
fillCircle(x, y, radius, color)	Draws a filled circle.
drawTriangle(x1, y1, x2, y2, x3, y3, color)	Draws a triangle
drawRoundRect(x, y, width, height, radius, color)	Draws an empty rectangle with rounded corners.
fillRoundRect(x, y, width, height, radius, color)	Draws a filled rectangle with rounded corners.

Execution Result

4. ASCII Code Output

This is an example of outputting characters corresponding to ASCII codes 1 to 8.

For more characters, please refer to the ASCII code table.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_ADDR 0x3C 

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR);
  display.clearDisplay(); // Clear the screen

  // Text output settings
  display.setTextSize(1);       // Set text size
  display.setTextColor(WHITE);  // Set text color
  display.setCursor(0, 0);      // Set cursor position

  // Print ASCII code characters
  display.println("ASCII Code Print");

  // Print ASCII code characters
  for (char c = 1; c < 9; c++) { // From ASCII code 1 to 8
      display.print(c);                // Print each character
      display.print(" ");              // Add space
  }

  display.display(); // Display the buffer content on the screen
}

void loop() {
}

Execution Result

5. Bitmap Image Output

This is an example of outputting an image on the OLED by converting it into a byte array.

How to Convert an Image to a Byte Array

1. Go to image2cpp (javl.github.io).

2. Upload Image

Select a file to upload from the left-side Select image.

3. Image Settings

Enter the image size in the Canvas size field and check the Preview. If the image is too large and the Canvas size is not properly adjusted, the image may not display correctly in the Preview.

4. Output

Set the Code output format to Arduino Code and click Generate code. The array will be displayed below.

Copy the output array and use it in the example code.

Code

You can use the drawBitmap(x, y, bitmap, width, height, color) function to draw a bitmap image at a specified position.

The color is set to white, so the image will be displayed in white.

Change the const unsigned char ~ part on line 12 to the byte array you created above.

If the example image (64 x 64 size) is different in size, you will need to adjust the x and y cursor positions, as well as the width and height values in the drawBitmap function on line 56 to match the image size.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_ADDR 0x3C 

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// GONGZIPSA LOGO
const unsigned char GONGZIPSA [] PROGMEM = { 
	0xff, 0xff, 0xff, 0xf0, 0x0f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x00, 0x7f, 0xff, 0xff, 
	0xff, 0xff, 0xf0, 0x00, 0x00, 0x0f, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x03, 0xff, 0xff, 
	0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xfc, 0x00, 0x00, 0x00, 0x00, 0x3f, 0xff, 
	0xff, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x0f, 0xff, 
	0xff, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0x80, 0x00, 0x10, 0x00, 0x40, 0x01, 0xff, 
	0xff, 0x00, 0x00, 0x30, 0x00, 0xe0, 0x00, 0xff, 0xff, 0x00, 0x00, 0x70, 0x00, 0xf0, 0x00, 0xff, 
	0xfe, 0x00, 0x00, 0xf0, 0x00, 0xf8, 0x00, 0x7f, 0xfc, 0x00, 0x01, 0xf0, 0x00, 0xfc, 0x00, 0x3f, 
	0xf8, 0x00, 0x03, 0xf0, 0x00, 0xfc, 0x00, 0x1f, 0xf8, 0x00, 0x03, 0xf0, 0x00, 0xff, 0x00, 0x1f, 
	0xf0, 0x00, 0x07, 0xf0, 0x00, 0xff, 0xe0, 0x07, 0xff, 0x80, 0x3e, 0xf0, 0x01, 0xff, 0xf8, 0x7f, 
	0xbf, 0xf1, 0xff, 0xe0, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x03, 0xff, 0xff, 0xf7, 
	0xdf, 0xff, 0xff, 0xf0, 0x0f, 0xef, 0xff, 0xf3, 0xc7, 0xdf, 0xff, 0xf0, 0x0f, 0xe7, 0xff, 0x63, 
	0xc3, 0xff, 0xfc, 0xb0, 0x0f, 0xef, 0xff, 0xe3, 0x81, 0xff, 0xf9, 0xb0, 0x0f, 0xff, 0xff, 0xc1, 
	0x80, 0xff, 0xf1, 0x70, 0x07, 0xff, 0xcd, 0xc1, 0x80, 0xf9, 0xfc, 0xf0, 0x0f, 0xff, 0xef, 0xc1, 
	0x80, 0xc9, 0xff, 0xf0, 0x0f, 0xff, 0xff, 0xe1, 0x80, 0x5c, 0xff, 0xe0, 0x07, 0xfb, 0xff, 0xc1, 
	0x00, 0x7f, 0xcf, 0xe0, 0x07, 0xfb, 0xff, 0xc0, 0x00, 0x3f, 0xcf, 0xc0, 0x03, 0xff, 0xff, 0x80, 
	0x00, 0x1f, 0xff, 0x80, 0x01, 0xff, 0xff, 0x80, 0x00, 0x0f, 0xff, 0x00, 0x00, 0x7f, 0xff, 0x00, 
	0x00, 0x07, 0xff, 0x80, 0x00, 0xff, 0xfe, 0x00, 0x00, 0x01, 0xff, 0x80, 0x00, 0xff, 0xf4, 0x00, 
	0x00, 0x00, 0x7f, 0xc0, 0x01, 0xff, 0x90, 0x00, 0x00, 0x00, 0xff, 0xe0, 0x03, 0xff, 0x80, 0x00, 
	0x80, 0x00, 0xff, 0xe0, 0x03, 0xff, 0x80, 0x01, 0x80, 0x00, 0x73, 0x30, 0x02, 0x07, 0x00, 0x01, 
	0x80, 0x71, 0xcb, 0x4e, 0x7d, 0x78, 0xf0, 0x81, 0x81, 0xf3, 0xec, 0xdf, 0x7f, 0xfd, 0xf1, 0x81, 
	0x81, 0x06, 0x2c, 0xf0, 0x0b, 0xc7, 0x01, 0x81, 0xc1, 0x04, 0x7c, 0xe0, 0x13, 0xcf, 0x83, 0x83, 
	0xc3, 0x3c, 0x7a, 0xe6, 0x23, 0xf9, 0xf2, 0xc3, 0xc3, 0x1c, 0x73, 0xe2, 0x63, 0x80, 0x16, 0xc3, 
	0xe3, 0x1c, 0x53, 0xe2, 0xc3, 0x80, 0x17, 0xc7, 0xe3, 0xf7, 0xd1, 0xff, 0xf7, 0x83, 0xfc, 0xc7, 
	0xf1, 0xe3, 0x91, 0x3f, 0xff, 0x03, 0xc8, 0x4f, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x0f, 
	0xf8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 
	0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x3f, 0xfe, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x7f, 
	0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 
	0xff, 0x80, 0x00, 0x00, 0x00, 0x00, 0x01, 0xff, 0xff, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x03, 0xff, 
	0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x0f, 0xff, 0xff, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xff, 
	0xff, 0xfc, 0x00, 0x00, 0x00, 0x00, 0x3f, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 
	0xff, 0xff, 0xc0, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x00, 0x00, 0x0f, 0xff, 0xff, 
	0xff, 0xff, 0xfe, 0x00, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x0f, 0xff, 0xff, 0xff
};

void setup() {
  display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR);
  display.clearDisplay(); // Screen initialization
}

void loop() {
  display.clearDisplay(); // Clear the screen

  // Drawing a 64x64 bitmap image
  display.drawBitmap(32, 0, GONGZIPSA, 64, 64, WHITE); // (x, y, bitmap, width, height, color)

  display.display(); // Output the buffer contents to the screen
}

Execution Result

Due to flickering, the image appears cut off when captured, but in reality, the round logo is displayed clearly.

Purchase Link

GONGZIPSA