At the beginning of this year I received from Chinese company LILYGO a great 4.7 parallel epaper. I really like the update speed (650ms full update) and the communication speed compared with SPI.

So I decided not to reinvent the wheel and use the great component EPDiy that is also a project here in HackADay to drive them. Here is concept behind it:

https://github.com/martinberlin/cale-idf/wiki/Parallel-epapers-driven-by-Epdiy-with-I2S-Data-bus

What I did in my existing Cale-idf C++ Firmware is to make function wrappers to support most of EPDiy functions but using Adafruit GFX functions and font support.

Proof of concept video

Flashing and rendering a Bitmap downloaded using ESP32 WiFi
Documenting the parallel implementation idea