Oled not working on Nano or Pro Mirco

I’m using a 4pin I2C 0.96 Inch 128X64 Oled Display, aliexpr link
wen I use it on a Arduino Leonardo It works fine,
But wen I want to use it on Nano or Pro Micro it will not work,
Using a address scanner sketch I find nothing on I2C.
I tried using different library’s and sketches on the Leonardo everything works fine.

I use Leonardo R3 Atmega32u4

Pro Micro ATmega32U4 whit NRF24L01. aliexp link

Nano V3.0 ATMEGA328P whit NRF24L01. aliexpress link

This is how I wired everything

Oled - Leonardo
SCL - SCL 
SDA - SDA
GND -GND
VCC - 3.3V

Oled - Pro Micro
SCL - 3
SDA - 2
GND -GND
VCC - VCC

Oled - Nano
SCL - 5
SDA - 4
GND -GND
VCC - 3v

This the sketch I like to get to work, just a simple Temp and Humility display

#include "DHT.h"
#define DHT11Pin 4
#define DHTType DHT22
//OLED
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

DHT HT(DHT11Pin,DHTType);
float tempC;
float humi;

//float tempF;

//OLED define
#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)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  Serial.begin(9600);
  //For DHT11
  HT.begin();
  //For OLED I2C
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  display.display(); //Display logo
  delay(1000); 
  display.clearDisplay();
}

void loop() {
 delay(1000);
 tempC = HT.readTemperature();
 humi = HT.readHumidity();
 
 //tempF = HT.readTemperature(true);

 Serial.print("Humidity:");
 Serial.print(humi,0);
 Serial.print("%");
 Serial.print(" Temperature:");
 Serial.print(tempC,1);
 Serial.print("C ~ ");
// Serial.print(tempF,1);
// Serial.println("F");

 display.clearDisplay();
 oledDisplayHeader();
 
 oledDisplay(2,0,0,tempC, "C");
 oledDisplay(3,60,30, humi,"%");
// oledDisplay(2,70,44,tempF,"F");
 
 display.display(); 
 
}
void oledDisplayHeader(){
 display.setTextSize(3);
 display.setTextColor(WHITE);
 display.setCursor(20, 30);
 display.print("RV ");
// display.setCursor(30, 0);
// display.print("Temperature");
}
void oledDisplay(int size, int x,int y, float value, String unit){
 int charLen=12;
 int xo=x+charLen*3.2;
 int xunit=x+charLen*3.6;
 int xval = x; 
 display.setTextSize(size);
 display.setTextColor(WHITE);
 
 if (unit=="%"){
   display.setCursor(x, y);
   display.print(value,0);
   display.print(unit);
 } else {
   if (value>99){
    xval=x;
   } else {
    xval=x+charLen;
   }
   display.setCursor(xval, y);
   display.print(value,0);
   display.drawCircle(xo, y+3, 3, WHITE);  // print degree symbols (  )
   display.setCursor(xunit, y);
   display.print(unit);
 }
 
}

I googled and did read a lot but nothing helped so far

Go on. It is pretty straightforward. The OP has:

Oled - Nano

SCL - 5
SDA - 4
GND -GND
VCC - 3v

when it should be:

Oled - Nano
SCL - A5
SDA - A4
GND -GND
VCC - 3v

Most will also be happy with VCC = 5V as well but we need to see pcb or a link to your OLED.
Most have on-pcb pullups. Again, we need a link to verify.

David.

when it should be:

Oled - Nano

SCL - A5
SDA - A4
GND -GND
VCC - 3v

I did use the the A ports and did try switching those 2

the Oled runs at and 3v and 5v I did try it out on the Leonardo and did work fine on ether of them.
Oled aliexpr link

Do you have 4k7 pull-ups to the 3.3 V Vcc of the OLED, on SDA and SCL?

I'm not using any extra ones, there are some on the Oled pcb it self I think

Just want to give a update that I frigged out why i did not get it to work on a nano or pro mirco.
Who knows it might help some one out :wink:

Cheap Breadboard was not making proper connections.

after i did some soldering direct on a nano it all worked just fine :slight_smile: