hello, I’m very new to this, but I just got my featherwing oled working in a basic mode. Are you including the “oled-wing-adafruit.h” program from the library? It works, just press A button after you load it. Hope this helps.
What exact display are you using?
How have you wired the display?
Have you set it for SPI use?
How do you supply the signal to your input pin?
Is D7 LED going on as expected?
Does any of the Adafruit_SSD1306 samples work?
This does not fit the code.
With this instruction Adafruit_SSD1306 display(OLED_DC,OLED_CS,OLED_RESET); you are telling the library to use SPI and consequently you don’t use the I2C pins D0/D1 on the controller but the SPI pins A4 (MISO) & A5 (MOSI) and you need to connet the CLK pin to A3 (SCK) - also your code has #define OLED_RESET D5 yet you wire RES-D2
This doesn’t really qualify as a sufficient answer to
There are several different versions of that with different pin designations and some of them even have solder jumpers to select I2C or SPI.
See, there you are.
In the top left corner you have a legend that tells you how the solder jumpers of your display need to be set for what interface mode.
Since yours is set for 4-wire SPI, you need to wire it exactly for that and use the respective library constructor.