I made a LED matrix clock using esp32 syncing time with ntp server every hour and an external RTC to do time keeping if my network is down, and it runs perfectly for years, with accuracy +-1s to time.is. Never have to do setting except the first boot to setup wifi.

The main reason i'm sticking around with embedded, seeing your code manifest to physical action is just...fun. No matter how good is your simulator/emulator, nothing beats real life.

But still, that does not prevent one from measuring the voltage directly at pixel.

Also when pushing for high refresh rate, you may need to use higher voltage, to make the droplets rise/fall faster. But sometime, those droplets are driven too hard and kind of stuck forever, so yeah, that's a trade off.

I have a question, hope it's not too sensitive, how do you guy protect your secret waveform ? One with enough tool and determination can just measure voltage at pixel and reverse the whole thing, the chinese can do that in less than a week i bet.

The thing is, Eink's waveform is kind of secret afaik, everyone has different tuning.

It will never be both objectively and subjectively equal. Even the geographic is already difference, the weather, then there is people, wealth, etc.

If you dive into even more niche, NDA-Only MCU, We have BES2700 MCU, which is even better

a picture is worth a thousand words. Of course your text article can have pictures, but how can you sure you include all the "useful" pictures. Then there is animation which is impossible to do with static picture.