diy smartwatch

Projects General Guidance
1

So I have been contemplating a DIY smartwatch project, and mentally (along with research/experience) I have figured out most of the project, but the one thing I am still wondering is how I would get notifications from my android phone to my (hypothetical)watch over Bluetooth. If any insight could be provided into this subject I would be grateful.

PS I have done some extremely basic (and by basic I mean I have only programmed for 4ish hours) programming in java/XML in android studio. I'm also fairly adept in arduino programming and electronics, owning an arduino since 2011. IDK if it matters though, and any help would be greatly apreciated

2

I'm going to throw-out one comment... The smaller you make something the more difficult it is for a do-it-yourselfer. Where I work we build some smallish boards (maybe about the size of an Apple watch) with Bluetooth and Wi-Fi but these are very dense boards with lots of tiny surface mount components packed on both sides of the board. It's assembled with automated equipment. It's not something that's practical to hand solder.