GxEPD2 Partial refresh takes 3 seconds instead of 0.3 seconds. How come?

[toddnz]

@Thomasx

And the reason it is run 13 times is, if I understand things correctly, because the memory of my Pro Micro is not large enough to fit the frame-buffer for the partial window in one go.

Correct! Known as "paging".

@Thomasx

But I just got a Pi Pico, so I might try that one instead then, to see if that one will work better

The size of these "slices" is set by the "page height". You set this when declaring your display:

GxEPD2_DISPLAY_CLASS<GxEPD2_DRIVER_CLASS, MAX_HEIGHT(GxEPD2_DRIVER_CLASS)> display(GxEPD2_DRIVER_CLASS(/*CS=*/ 9, /*DC=*/ 8, /*RST=*/ 12, /*BUSY=*/ 13));

(source)

Note the MAX_HEIGHT(GxEPD2_DRIVER_CLASS) argument in there. This sets page height to the same as the display height, meaning you only use one page. This will only work if your device has enough RAM (like the Pi Pico)

If you wanted to, for some reason, you could also manually set a different page height there.