0.96″ Inch 128×64 3.3V I2C OLED Blue Display Module with 4-Key Matrix Keyboard Interface Full View (SSD1315 Driver)

Pinout & Connection Guide

The module features a 4-pin I2C interface for easy connection to your microcontroller.

Pin Definitions (4-Pin)

I2C Pin Mapping for Common Development Boards

Wiring Diagram (ESP32)

OLED Module          →    ESP32
─────────────────────────────────────
VCC                  →    3.3V
GND                  →    GND
SCL                  →    GPIO22 (SCL)
SDA                  →    GPIO21 (SDA)

Important Electrical Notes:

• This module operates at 3.3V only. Do not connect VCC to 5V.

• The four tactile buttons are connected to the I2C bus via pull-up resistors . They share the same SDA/SCL lines as the display.

• If you need to add multiple I2C devices, be aware that the buttons add capacitance to the bus (approximately 85pF with three devices) . An I2C multiplexer may be required for complex multi-device setups.

Usage Guide

Software Setup (Arduino IDE)

Step 1: Install Required Libraries

The U8g2 library by Oliver Kraus is the most reliable choice for SSD1315 displays, offering excellent support and many font options.

1. Open Arduino IDE → Sketch → Include Library → Manage Libraries

2. Search for “U8g2” by Oliver Kraus

3. Click Install

4. (Optional) For keypad support, install “Adafruit Keypad” library

Step 2: Basic Test Sketch

#include <Arduino.h>
#include <U8g2lib.h>
#include <Wire.h>

// Hardware I2C mode – uses default I2C pins
U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE);

void setup() {
  u8g2.begin();                          // Initialize display
  u8g2.enableUTF8Print();                // Enable UTF8 characters if needed
  u8g2.setFont(u8g2_font_ncenB08_tr);    // Choose a suitable font
}

void loop() {
  u8g2.firstPage();                      // Start page loop
  do {
    u8g2.drawStr(0, 15, "0.96 OLED");
    u8g2.drawStr(0, 35, "128x64");
    u8g2.drawStr(0, 55, "SSD1315");
  } while ( u8g2.nextPage() );           // Transfer buffer to display
  
  delay(1000);
}

Step 3: Using the 4 Keys

The four keys share the I2C bus with the display. The module uses 10kΩ pull-up resistors on the button lines . To read key presses, you can use the Adafruit Keypad library or directly read the I2C register values (consult the module’s specific documentation for register mapping).

Important Note on Debouncing: The mechanical buttons have a typical bounce time of 6.2ms ±1.4ms . For reliable key detection, implement a 10ms debounce window in your firmware to prevent false triggers.

Power Consideration: When a button is pressed, it can cause a momentary VDD drop of up to 0.3V, which may cause OLED brightness fluctuation . Adding a 0.1µF ceramic capacitor between VDD and GND near the module is recommended for stable operation.

Raspberry Pi Setup (Python)

1. Enable I2C: sudo raspi-config → Interface Options → I2C → Yes

2. Install required libraries:

sudo apt-get install python3-pip
pip3 install luma.oled

3. Python example code:

from luma.core.interface.serial import i2c
from luma.oled.device import ssd1306
from luma.core.render import canvas

# Create I2C interface (default address 0x3C)
serial = i2c(port=1, address=0x3C)

# Create display device
device = ssd1306(serial, width=128, height=64)

with canvas(device) as draw:
    draw.rectangle(device.bounding_box, outline="white", fill="black")
    draw.text((10, 20), "0.96 OLED", fill="white")
    draw.text((10, 40), "128x64", fill="white")

Understanding the Display Buffer Workflow (U8g2)

The U8g2 library uses a page-buffered approach to manage memory efficiently:

u8g2.firstPage();   // Start drawing session
do {
  // All drawing commands go here
  u8g2.drawStr(0, 20, "Hello");
} while ( u8g2.nextPage() );  // Transfer buffer to display and repeat

This structure allows the same code to work on both full-buffer and low-memory devices. The _F_ (full buffer) constructors use more RAM but provide smoother updates.

SSD1315 Driver Notes

The SSD1315 is the driver IC for this 0.96″ OLED module . It is compatible with the SSD1306 command set, meaning existing SSD1306 libraries (including U8g2 and Adafruit_SSD1306) will work with this display . The SSD1315 supports I2C clock speeds up to 1MHz, though many modules are limited to 400kHz for compatibility.

Key Advantage: The SSD1315 has better timing tolerance than the SSD1306, with SCL rise times of approximately 110ns compared to 280ns on SSD1306 modules . This makes it more reliable for high-speed I2C communication.