Driving InkyPHAT display directly


#1

I obtained that display lately but i am not satisfied about the way it is updated with all this flickering
taking 15 seconds. I found that it is delibaretale done in the inky library:


under it I can find that display is driven with SPI commands, but neither the commands nor what
the display is, is documented anywhere. Can i found this information somewhere. I am interested
is it possibly to just update parts of the display at time.


#2

Line 120 is not relevant, it’s marked ignore because it serves no purpose in the hardware (presumably it’s reserved for future 4-colour displays), and is not related at all to the display flicker.

The flickering is deliberate and intended to control image retention, since image quality otherwise very quickly degrades. It’s moving physical ink particles in a fluid suspension, and these steps bring the ink back into a - more or less - clean state ready for the next image to be displayed.

See https://github.com/pimoroni/inky/issues/13 for a more general overview of the Inky LUTS and what they actually mean (insofar as I understand them.)

The datasheet is here: https://www.china-epaper.com/uploads/soft/DEPG0420R01V3.0.pdf


#3

line 126 would have been more appropriate point.

Anyway thanks for pointing me to the LUTs documentation.
It seems that red is the slowest color to be turned on.

I managed on my first try to generate ‘fast update’ LUT,
that leaves the red pigment unchanged and only changes black on/off
I wil try to refine this LUT on coming weekend.

first normal update is used and then text changed with the fast black only update


#4

Okay- that’s seriously cool! Really nice work.

I’ve done some more work on the library to revise the presentation of LUTs and better document them.

I hope to separate them out into another file, and perhaps even make it possible to extend Inky with custom LUTs.