Sample code for driving 128x64 OLED display with SSD1306 driver via ESP-IDF's I2C master driver ====================
See main code main.c.
This sample code implement procedures to read values from 128x64 OLED display with SSD1306 driver via ESP-IDF's I2C master driver. It supports all features decribed in Solomon Systech's SSD1306 datasheet.
----------For local setup ----------
For your local setup, connect SDI pin to GPIO 15 pin and the SCK to GPIO 2 pin as they are default ports (I2C_SDA, I2C_SCL) for I2C master according to ESP32 datasheet, C.4. IO_MUX, Page 49.
Be aware about there are serveal models on 128x64 OLED display with SSD1306. Like one model with more pins works with both SPI/I2C, and another model with lesser pins works I2C only. This cample code is confirmed with a OLED model which have (GND, VDD, SCK, SDA) pins and it supports I2C only (no SPI available). Perhaps your model has slightly different pins, but it should works.
In case it does not work, please check your circit. Consider insert 10k ohm pull-up registors on between 3.3v power supply and (SDA, SCK) pins respectively, as OLED display consumes larger current comparing with other tiny I2C sensors. In my case, 10k ohm pull-up registors stabilized voltage level for clock and SDA and the code worked correctly.