Oled SSD1306 i2c not working

Hi! Why can't I get a regular OLED screen SSD1306 like this one:

To work on my Arduino Uno Wifi rev2?

Using the example sketches for i2c 128x64, changing the reset pin to - 1 from 4, and using the address provided by the manufacturer 0x78, 0x3D, 0x3C doesn't seem to work. Is this not compatible with the Uno wifi?

Please post your code as well

There is an I2C scanner in the Arduino IDE examples. It is the first thing you should load and run whenever you start up a new device. It will list the addresses that are sensed by the Arduino.

thank you for your help.

To answer your questions, this is the code im using to for the display to test:

/**************************************************************************
This is an example for our Monochrome OLEDs based on SSD1306 drivers

Pick one up today in the adafruit shop!
------> http://www.adafruit.com/category/63_98

This example is for a 128x64 pixel display using I2C to communicate
3 pins are required to interface (two I2C and one reset).

Adafruit invests time and resources providing this open
source code, please support Adafruit and open-source
hardware by purchasing products from Adafruit!

Written by Limor Fried/Ladyada for Adafruit Industries,
with contributions from the open source community.
BSD license, check license.txt for more information
All text above, and the splash screen below must be
included in any redistribution.
**************************************************************************/

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

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
// The pins for I2C are defined by the Wire-library.
// On an arduino UNO: A4(SDA), A5(SCL)
// On an arduino MEGA 2560: 20(SDA), 21(SCL)
// On an arduino LEONARDO: 2(SDA), 3(SCL), ...
#define OLED_RESET 4 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3D ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define NUMFLAKES 10 // Number of snowflakes in the animation example

#define LOGO_HEIGHT 16
#define LOGO_WIDTH 16
static const unsigned char PROGMEM logo_bmp =
{ 0b00000000, 0b11000000,
0b00000001, 0b11000000,
0b00000001, 0b11000000,
0b00000011, 0b11100000,
0b11110011, 0b11100000,
0b11111110, 0b11111000,
0b01111110, 0b11111111,
0b00110011, 0b10011111,
0b00011111, 0b11111100,
0b00001101, 0b01110000,
0b00011011, 0b10100000,
0b00111111, 0b11100000,
0b00111111, 0b11110000,
0b01111100, 0b11110000,
0b01110000, 0b01110000,
0b00000000, 0b00110000 };

void setup() {
Serial.begin(9600);

// SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
Serial.println(F("SSD1306 allocation failed"));
for(;;); // Don't proceed, loop forever
}

// Show initial display buffer contents on the screen --
// the library initializes this with an Adafruit splash screen.
display.display();
delay(2000); // Pause for 2 seconds

// Clear the buffer
display.clearDisplay();

// Draw a single pixel in white
display.drawPixel(10, 10, SSD1306_WHITE);

// Show the display buffer on the screen. You MUST call display() after
// drawing commands to make them visible on screen!
display.display();
delay(2000);
// display.display() is NOT necessary after every single drawing command,
// unless that's what you want...rather, you can batch up a bunch of
// drawing operations and then update the screen all at once by calling
// display.display(). These examples demonstrate both approaches...

testdrawline(); // Draw many lines

testdrawrect(); // Draw rectangles (outlines)

testfillrect(); // Draw rectangles (filled)

testdrawcircle(); // Draw circles (outlines)

testfillcircle(); // Draw circles (filled)

testdrawroundrect(); // Draw rounded rectangles (outlines)

testfillroundrect(); // Draw rounded rectangles (filled)

testdrawtriangle(); // Draw triangles (outlines)

testfilltriangle(); // Draw triangles (filled)

testdrawchar(); // Draw characters of the default font

testdrawstyles(); // Draw 'stylized' characters

testscrolltext(); // Draw scrolling text

testdrawbitmap(); // Draw a small bitmap image

// Invert and restore display, pausing in-between
display.invertDisplay(true);
delay(1000);
display.invertDisplay(false);
delay(1000);

testanimate(logo_bmp, LOGO_WIDTH, LOGO_HEIGHT); // Animate bitmaps
}

void loop() {
}

void testdrawline() {
int16_t i;

display.clearDisplay(); // Clear display buffer

for(i=0; i<display.width(); i+=4) {
display.drawLine(0, 0, i, display.height()-1, SSD1306_WHITE);
display.display(); // Update screen with each newly-drawn line
delay(1);
}
for(i=0; i<display.height(); i+=4) {
display.drawLine(0, 0, display.width()-1, i, SSD1306_WHITE);
display.display();
delay(1);
}
delay(250);

display.clearDisplay();

for(i=0; i<display.width(); i+=4) {
display.drawLine(0, display.height()-1, i, 0, SSD1306_WHITE);
display.display();
delay(1);
}
for(i=display.height()-1; i>=0; i-=4) {
display.drawLine(0, display.height()-1, display.width()-1, i, SSD1306_WHITE);
display.display();
delay(1);
}
delay(250);

display.clearDisplay();

for(i=display.width()-1; i>=0; i-=4) {
display.drawLine(display.width()-1, display.height()-1, i, 0, SSD1306_WHITE);
display.display();
delay(1);
}
for(i=display.height()-1; i>=0; i-=4) {
display.drawLine(display.width()-1, display.height()-1, 0, i, SSD1306_WHITE);
display.display();
delay(1);
}
delay(250);

display.clearDisplay();

for(i=0; i<display.height(); i+=4) {
display.drawLine(display.width()-1, 0, 0, i, SSD1306_WHITE);
display.display();
delay(1);
}
for(i=0; i<display.width(); i+=4) {
display.drawLine(display.width()-1, 0, i, display.height()-1, SSD1306_WHITE);
display.display();
delay(1);
}

delay(2000); // Pause for 2 seconds
}

void testdrawrect(void) {
display.clearDisplay();

for(int16_t i=0; i<display.height()/2; i+=2) {
display.drawRect(i, i, display.width()-2i, display.height()-2i, SSD1306_WHITE);
display.display(); // Update screen with each newly-drawn rectangle
delay(1);
}

delay(2000);
}

void testfillrect(void) {
display.clearDisplay();

for(int16_t i=0; i<display.height()/2; i+=3) {
// The INVERSE color is used so rectangles alternate white/black
display.fillRect(i, i, display.width()-i2, display.height()-i2, SSD1306_INVERSE);
display.display(); // Update screen with each newly-drawn rectangle
delay(1);
}

delay(2000);
}

void testdrawcircle(void) {
display.clearDisplay();

for(int16_t i=0; i<max(display.width(),display.height())/2; i+=2) {
display.drawCircle(display.width()/2, display.height()/2, i, SSD1306_WHITE);
display.display();
delay(1);
}

delay(2000);
}

void testfillcircle(void) {
display.clearDisplay();

for(int16_t i=max(display.width(),display.height())/2; i>0; i-=3) {
// The INVERSE color is used so circles alternate white/black
display.fillCircle(display.width() / 2, display.height() / 2, i, SSD1306_INVERSE);
display.display(); // Update screen with each newly-drawn circle
delay(1);
}

delay(2000);
}

void testdrawroundrect(void) {
display.clearDisplay();

for(int16_t i=0; i<display.height()/2-2; i+=2) {
display.drawRoundRect(i, i, display.width()-2i, display.height()-2i,
display.height()/4, SSD1306_WHITE);
display.display();
delay(1);
}

delay(2000);
}

void testfillroundrect(void) {
display.clearDisplay();

for(int16_t i=0; i<display.height()/2-2; i+=2) {
// The INVERSE color is used so round-rects alternate white/black
display.fillRoundRect(i, i, display.width()-2i, display.height()-2i,
display.height()/4, SSD1306_INVERSE);
display.display();
delay(1);
}

delay(2000);
}

void testdrawtriangle(void) {
display.clearDisplay();

for(int16_t i=0; i<max(display.width(),display.height())/2; i+=5) {
display.drawTriangle(
display.width()/2 , display.height()/2-i,
display.width()/2-i, display.height()/2+i,
display.width()/2+i, display.height()/2+i, SSD1306_WHITE);
display.display();
delay(1);
}

delay(2000);
}

void testfilltriangle(void) {
display.clearDisplay();

for(int16_t i=max(display.width(),display.height())/2; i>0; i-=5) {
// The INVERSE color is used so triangles alternate white/black
display.fillTriangle(
display.width()/2 , display.height()/2-i,
display.width()/2-i, display.height()/2+i,
display.width()/2+i, display.height()/2+i, SSD1306_INVERSE);
display.display();
delay(1);
}

delay(2000);
}

void testdrawchar(void) {
display.clearDisplay();

display.setTextSize(1); // Normal 1:1 pixel scale
display.setTextColor(SSD1306_WHITE); // Draw white text
display.setCursor(0, 0); // Start at top-left corner
display.cp437(true); // Use full 256 char 'Code Page 437' font

// Not all the characters will fit on the display. This is normal.
// Library will draw what it can and the rest will be clipped.
for(int16_t i=0; i<256; i++) {
if(i == '\n') display.write(' ');
else display.write(i);
}

display.display();
delay(2000);
}

void testdrawstyles(void) {
display.clearDisplay();

display.setTextSize(1); // Normal 1:1 pixel scale
display.setTextColor(SSD1306_WHITE); // Draw white text
display.setCursor(0,0); // Start at top-left corner
display.println(F("Hello, world!"));

display.setTextColor(SSD1306_BLACK, SSD1306_WHITE); // Draw 'inverse' text
display.println(3.141592);

display.setTextSize(2); // Draw 2X-scale text
display.setTextColor(SSD1306_WHITE);
display.print(F("0x")); display.println(0xDEADBEEF, HEX);

display.display();
delay(2000);
}

void testscrolltext(void) {
display.clearDisplay();

display.setTextSize(2); // Draw 2X-scale text
display.setTextColor(SSD1306_WHITE);
display.setCursor(10, 0);
display.println(F("scroll"));
display.display(); // Show initial text
delay(100);

// Scroll in various directions, pausing in-between:
display.startscrollright(0x00, 0x0F);
delay(2000);
display.stopscroll();
delay(1000);
display.startscrollleft(0x00, 0x0F);
delay(2000);
display.stopscroll();
delay(1000);
display.startscrolldiagright(0x00, 0x07);
delay(2000);
display.startscrolldiagleft(0x00, 0x07);
delay(2000);
display.stopscroll();
delay(1000);
}

void testdrawbitmap(void) {
display.clearDisplay();

display.drawBitmap(
(display.width() - LOGO_WIDTH ) / 2,
(display.height() - LOGO_HEIGHT) / 2,
logo_bmp, LOGO_WIDTH, LOGO_HEIGHT, 1);
display.display();
delay(1000);
}

#define XPOS 0 // Indexes into the 'icons' array in function below
#define YPOS 1
#define DELTAY 2

void testanimate(const uint8_t *bitmap, uint8_t w, uint8_t h) {
int8_t f, icons[NUMFLAKES][3];

// Initialize 'snowflake' positions
for(f=0; f< NUMFLAKES; f++) {
icons[f][XPOS] = random(1 - LOGO_WIDTH, display.width());
icons[f][YPOS] = -LOGO_HEIGHT;
icons[f][DELTAY] = random(1, 6);
Serial.print(F("x: "));
Serial.print(icons[f][XPOS], DEC);
Serial.print(F(" y: "));
Serial.print(icons[f][YPOS], DEC);
Serial.print(F(" dy: "));
Serial.println(icons[f][DELTAY], DEC);
}

for(;:wink: { // Loop forever...
display.clearDisplay(); // Clear the display buffer

// Draw each snowflake:
for(f=0; f< NUMFLAKES; f++) {
  display.drawBitmap(icons[f][XPOS], icons[f][YPOS], bitmap, w, h, SSD1306_WHITE);
}

display.display(); // Show the display buffer on the screen
delay(200);        // Pause for 1/10 second

// Then update coordinates of each flake...
for(f=0; f< NUMFLAKES; f++) {
  icons[f][YPOS] += icons[f][DELTAY];
  // If snowflake is off the bottom of the screen...
  if (icons[f][YPOS] >= display.height()) {
    // Reinitialize to a random position, just off the top
    icons[f][XPOS]   = random(1 - LOGO_WIDTH, display.width());
    icons[f][

Hello
run the simplest example you can find in the WWW to check hardware.

1 Like

That's probably the best way to go, I got that from the adafruit ssd1306 example library.

As for scanning the I2C port, I wasn't able to find an example in IDE but found this script:

https://playground.arduino.cc/Main/I2cScanner/

and when I ran it, at said this:

22:02:09.208 -> Scanning...
22:02:09.249 -> I2C device found at address 0x60 !
22:02:09.289 -> done
22:02:09.289 ->

and thought this was the address of the OLED screen, so I updated the SSD1306 script to this new address, still didn't work. But, then I completely disconnected the OLED screen from the board, and it still said I2C device has been detected?

Take a view into the examples provided located in the IDE.

Ok, problem is solved, mostly.

Here is the solution. I put the SDA and SCL pins on A4 and A5, which as you know, should not be the case for the Uno Wifi Rev2. after putting the pins in the correct holder, i.e. the SDA and SCL pins of Uno Wifi Rev2 board AND doing the I2C scanner, I was able to get the screen to work.

Here's my follow up question: the I2C scanner found the address as the 128x32 (0x3C) screen, but my screen should be a 128X64 screen (0x3D). I realize I2C addresses can be modified so its a moot point, but wanted to check if this normal.

thanks for all your help!!

I2C address 0x60 is the onboard security chip.
If your OLED display is at 0x3C, then use 0x3C. It is as simple as that. Don't overthink it.

The SDA and SCL pins of a OLED display are for a 3.3V I2C bus. Your Arduino board has a 5V I2C bus. The more sensors you add to the I2C bus, the more that could become a problem.

1 Like