I will explain in more details how this kind of display works.
This display will be later on used for more useful purpose that just display a still image ;)
Depending on the target application (not yet clearly defined!) I will develop either more efficient software if it is intended to be used with a micro-controller, or an IP for FPGA to interface with this display.
Quick update (July 07, 2022):
After some serious optimization and use of SPI (end of the bit-banging for the data transmission!), much more processing power is available to do more useful thing than just display a still image.
Posted a very small video to give an idea of new possibilities.
I'll come back to describe more in depth operation and optimizations done.
To be continued!
Here is one: https://github.com/mariosgit/VFD/tree/master/lib/VFD_MN12832L