Pulsed LED display vs always-on readout - which would you pick for a watch build?

I built something similar a couple years back with an e-ink module from a cheap weather station, and I can tell you the driver is even more fiddly than you'd guess. The refresh sequence has this wierd timing dance and if you get one register wrong the panel just ghosts old pixels everywhere. That said, once it worked I never touched it again, and the thing still shows the time on a shelf in my workshop two battery swaps later.

The part people underestimate is the button press thing. My first version was also press-to-read, and in real life I almost never pressed it. Cold morning, hands full, riding in a car, you just don't want to fumble with a button. It sat in a drawer within a month. A watch you have to interact with turns into a gadget, and gadgets get abandoned.

So my vote is e-ink, even with the hassle. The charm of a binary watch is decoding it in your head, and you can still do that at a glance since the pattern just sits there. Battery life goes from silly-long to merely great, and you stop caring about microamps entirely, wich honestly felt like the real win. If you do go that route, buy the module with a breakout board first and get the driver working on a dev board before you commit to the tiny panel. Saved me from ordering the wrong size twice.

I went through the same debate on a bedside clock project and ended up with one of those memory-in-pixel LCDs pulled from a dead fitness band. It holds the image with basically no current, only sips power when the pixels change once a minute, and you can read it in daylight without pressing anything. In the dark it's useless though, so I kept a single LED behind it that lights for a second when I tap the case. Best of both, and the coin cell is still going after a year and a half.

Honestly though, on the wrist I might just keep what you have. Mine was a binary display too at one point and I found the little mental pause of decoding it became part of the fun. After a few weeks you read it instantly anyway, same as reading an analog face. The wife test is the real spec, I'll give you that. Mine called my version 'a puzzle pretending to be a watch' and I still smile about it. If you do try the LCD route, check the current draw in the datasheet yourself before committing. Some of those panels look similar but draw noticeably different idle current, and it matters at coin cell scale.

I only ever got as far as a breadboard version of somthing like this, so take my take with a grain of salt. Mine was a binary desk clock, not a watch, and I left the LEDs on all the time thinking the decoding woud stay fun. What actualy happened is my brain got lazy after a week and now I just glance at it like a normal clock. So maybe the button press is what keeps the puzzle alive? Sort of hoping someone here has worn a binary one long term and can say wheather the decoding charm sticks or fades.

I keep seeing this idea that e-ink means you stop caring about microamps and I don't buy it. The panel itself sips, sure, but the driver chip behind it has its own sleep states, and if you get those wrong it drags the whole rail down. I put a small e-ink module on a datalogger once and the driver was quietly eating half my budget even with the display just sitting there. Had to cut a trace and add a switch to actually kill it between updates. So no, you don't escape the current obsession, it just moves to a diferent part of the board. If the LED version runs for years as-is, that's not a compromise I'd trade lightly.

My fix for the button problem was swapping it for a cheap accelerometer on a breakout board. A quick flick of the wrist wakes the LEDs, so no fumbling when your hands are full. It draws almost nothing in sleep, so the battery math barely changed, and honestly it made the watch feel more like a watch again. Cost me less than the coin cell holder did.

The battery math has a ceiling anyway, so I wouldn't sweat it too much. A coin cell self-discharges whether you use it or not, so past a certain point the pulsed version isn't actually gaining anything by idling harder. Might as well spend some of that headroom on being easier to live with. Mine's a press-to-read thing too and I still wear it, but mine lives on a shelf half the week, so maybe that proves the earlier point about gadgets. Curious if anyone's tried a hybrid, like the e-ink showing minutes and LEDs doing the binary part when you tap.