update only part of the screen? about inky

[Gadgetoid]

There's no hardware support for partial refresh, so unfortunately this is impossible. On bi-colour displays it's basically useless anyway as the way the display works is fuzzy enough that it distorts pixels around the partial update area (we saw this on our original prototypes with a different display part).

[chrislast]

The mono version at https://www.china-epaper.com/uploads/soft/DEPG0420A01V3.0.pdf suggests that SPI command 0x22 0xC0 will do a partial update in Section 13.4 even though it doesn't show it as supported in the command table. The multicolour manual at https://www.china-epaper.com/uploads/soft/DEPG0420R01V3.0.pdf doesn't even suggest it although it does still support the partial ram address commands 0x44, 0x45, 0x4e, 0x4f as well so it would probably work, possibly badly for the reasons Gadgetoid mentioned.

It looks like you'd have to keep the EPD powered up between partial refreshes to work correctly so you'll sacrifice some current. Not sure whether gadgetoid kept it powered when testing...

Anyway I came here wondering the same thing so now I know thanks for the answer :)

[MattiJarvinen]

Damn... Thanks for the info.

[STrRedWolf]

Just saw this and wondering if the Inky Impression was able to partially update. Different hardware and all.

[Gadgetoid]

Impression also cannot do partial updates for largely the same reasons. Frustrating because the update cycle is so long that you lose a bunch of ambient information for almost half a minute.