OLED displays are a useful upgrade over traditional character LCDs when an Arduino project needs a compact graphical interface. Since OLEDs provide individual pixel control, they can display text, shapes, icons, graphics, and simple animations while maintaining a thin and lightweight form factor.

In this project, I interfaced both I2C and SPI versions of a 0.96-inch 128×64 OLED display with an Arduino Nano. Both displays use the SSD1306 controller, making them a good choice for experimenting with graphical displays in Arduino projects.

OLED Display Overview

The OLED used in this project has a 128×64 pixel resolution and operates from a typical 3.3V–5V supply. Unlike conventional LCDs, OLED pixels produce their own light, so no backlight is required. This provides high contrast, deep blacks, and good viewing angles.

The SSD1306 controller receives commands and display data from the Arduino and controls the OLED pixels. It includes 1KB of internal Graphic Display Data RAM (GDDRAM), which stores the pixel information used to refresh the display.

The memory is divided into 8 pages, with each page containing 128 columns. Each column controls 8 vertical pixels:

8 pages × 128 columns × 8 bits

Total = 8,192 bits

Total memory = 1KB

A 128×32 OLED uses only four pages of this memory, while the remaining memory remains unused.

I2C OLED Display

The I2C version is particularly convenient because it requires only two communication lines in addition to power. The module typically includes the SSD1306 controller, voltage regulation, filtering capacitors, I2C pull-up resistors, and configuration jumpers.

The SSD1306 supports two commonly used 7-bit I2C addresses: 0x3C and 0x3D. The selected address depends on the configuration of the address jumper on the module.

I2C Pin Connections

GND → Arduino Nano GND

VCC → Arduino Nano 5V

SCL → Arduino Nano A5

SDA → Arduino Nano A4

With only four connections, the I2C OLED leaves most of the Arduino's digital pins available for other peripherals.

SPI OLED Display

The SPI version uses additional pins because the communication interface has separate clock, data, and control signals. Unlike I2C, SPI uses direct push-pull signaling and therefore does not require the same pull-up resistor arrangement.

SPI Pin Connections

GND → Arduino Nano GND

VCC → Arduino Nano 5V

SCK → Arduino Nano D10

MOSI → Arduino Nano D9

CS → Arduino Nano D12

D/C → Arduino Nano D11

Here, SCK provides the SPI clock and MOSI transfers data from the Arduino to the OLED. The CS pin selects the display, while D/C determines whether the transmitted information is interpreted as a command or display data.

Hardware Required

The basic hardware setup consists of:

Arduino Nano R3

0.96-inch 128×64 SSD1306 I2C OLED

0.96-inch 128×64 SSD1306 SPI OLED

USB A-to-Mini-B cable

Jumper wires

5V power supply

For software, the project uses the Arduino IDE and the Adafruit SSD1306 library. The Adafruit GFX library can also be used for drawing text and graphical elements.

Working with Graphics

One of the biggest advantages of an OLED over a character LCD is pixel-level control. Once the display is initialized, the Arduino can be used to create different graphical elements such as:

Text and numbers

Lines

Rectangles

Circles

Icons

Bitmap images

Sensor graphs

Progress indicators

Simple animations

This makes a small SSD1306 OLED useful for projects that need more than basic character-based information.

I2C vs SPI OLED

Both interfaces can be used with the same SSD1306-based OLED concept, but they have different wiring requirements.

I2C is a good choice when fewer Arduino pins are available because it requires only SDA and SCL for communication.

SPI requires more connections but provides dedicated communication and control lines, making it useful when SPI is already being used in a project or when a dedicated display interface is preferred.

Conclusion

Interfacing an SSD1306 OLED with an Arduino Nano is a straightforward way to add a compact graphical interface to an embedded project. The I2C version keeps the wiring simple, while the SPI version provides dedicated communication and control signals.

With pixel-level control and support for text, shapes, images, and other graphics, these displays can be used in a wide range of Arduino-based projects.

For the complete project, source code, detailed OLED memory explanation, and additional examples, visit Play with Circuit:

OLED Display with Arduino Tutorial