There’s QR code library for Arduino released 3 years ago. https://github.com/ricmoo/qrcode/ Well made library, works with less memory of Arduino while supporting QR code versions and error correction levels. You can easily create QR code data with above library and show code to OLED display with u8glib library. Below is sample sketch for showing QR code with “https://programresource.net” text data to OLED display, with inverted B/W on left / right half of screen. Very short and simple sketch which does amazing work.