It was funny to port i2c driver from 8-bit to 32-bit MCU. Lot of changes, but it was a big step forward. So seems to be that,  I have successfully ported my previously used OLED SSD1306 driver.

It just counts from 0-300, but image was stripped ;). I guess, for basic presentation is enough.

There is a lot of TODO points, but next step will be displaying value based on encoder rotation... .