I have been looking for a circular e-ink display that has a simple interface. This one ($99) has been around for a long time, but it seems like you have to buy their interface board ($350) to talk to it. So I assume it isn't easy.
Dig as I may, I can't get the raw interface spec. to see if I can understand it.
I have interfaced a bunch of other e-ink displays with SPI with little problem, but these circular ones lock up their spec tight.
Why do you think that might be?
There is a competitor display from China Gligo that has a smaller interface board and obscure spec, but is kind of clunky.
That seems to be it!
I found a product by Withings, and a teardown that seems to indicate it is a custom segmented display.