The previous OLED display was really cute for its small 128x32px size, but it wasn't working well for the QR code. 

Imagine a square with less than 10x10mm, shinning bright (OLED). It was really hard to focus with the smartphone camera.

I've then decided to switch for a similar but bigger I2C OLED display, now with 128x64px:

Then I've took advantage of its taller real state to improve and/or implement new screens:

• splash: more about that soon, with an nerdy extra feature;
• wi-fi reset;
• wi-fi setup: cold start or after reset;
• E-TKT ready state: QR code + text of the local assigned IP to access the web app;
• printing progress;
• printing finished;
• cutting, feeding and reeling: requested manually from the web app);
• saving settings: more about that in the following updates;
• rebooting;

It turns out that having not so many pixels to push around is pretty funny. Also, I've used symbols with a dedicated font to improve the meaning and communication.

Thanks to olikraus for the amazing U8g2 library that is super useful.