Open source hackable smart watch with app

forgive the lack of formality e.g. lack of proper sentence grammar or capitalization. im writing this more or less free thought so i can get it down and post the update while i have to do my regular job

current progress:

to be honest, other things have been keeping my attention (this is a side project/hobby after all), so not much progress in the last couple of weeks. however, i have made a mock kanban in google sheets with the following epics.

watch responds to bluetooth: 

the smart watch response to the adafruit bluetooth app

make a simple bluetooth app that watch responds to: 

making a very pared-down version of the adafruit bluetooth app that the smart watch responds to. my initial plan is to use react native so it can port to both android and ios, but failing that, i will make it in android, which is simply my preference for now

get watch buttons working (mock data):

1) mode select button: change between time, timer, and display
2) action button: executes simple action for each mode

send time via bluetooth:

simply have the watch set its time via the bluetooth app

send display via bluetooth:

whatever text is set in the app, it is synced to the device. see note below

compartmentalize watch functions:

toward the goal of making this easy for people to pick up and use, modify the smart watch code so that people can add or remove their own functions easily and cleanly

note on the "display" mode: this function may seem odd or out of place. i admit this open smart watch project is a stepping stone for a different project, but this way not only can i make what i need, but others can possibly benefit by my documentation here.

things i need to do for this project
- provide images / code / screenshots of current progress

Noting that I shifted the overall aim of this project to include a smart phone app to connect to a simple Arduino smart watch, so people can take that and run with it.

I am open to other technologies (e.g. ESP32 for the board and Gadgetbridge for the app)

Some links to places I've looked that had more information and resourcres:

Gadgetbridge

Asteroid OS

Open SmartWatch

ElectroNoobs - SmartWatch Firmware v2.0 - Some Arduino code I may utilize

My initial work uses the following hardware

- Adafruit Feather nRF52840 Express (https://www.adafruit.com/product/4062)

-- is discoverable by BlueTooth

-- has a Stemma connector, which I eventually abandoned

-- can connect with a battery

-- can recharge that battery

- Adafruit Grayscale 1.5" 128x128 OLED Graphic Display (https://www.adafruit.com/product/4741)

-- good screen size

-- Stemma connector

- Lithium Ion Polymer Battery - 3.7v 500mAh (https://www.adafruit.com/product/1578)

-- about the size of a US quarter, about 4mm thick, which is a decent small size

-- pretty good capacity

-- connects easily to the Feather board

I plan to try to either use a single board for bluetooth and magnetometer functionality, or get two smaller boards if the combined board has too many extras.

This board has both, but might end up having too much extra stuff (and it's $15 more than the other Feather): Adafruit Feather nRF52840 Sense (https://www.adafruit.com/product/4516)

Here is my current list of desirables

- bluetooth discoverability: so any phone can connect to it and send it data (two way communication NOT required)

- bluetooth communication including

-- phone sends message to display watch, not necessarily SMS

- magnetometer to track movement like gestures like left/right and show compass direction

- utilization of a battery with display of battery remaining

- ability to recharge battery via typical USB

- display that turns on with a button press (for the first version)

- watch functionality including

-- timer

-- stopwatch

-- set time and date

-- show current month calendar

-- change display between digital and analog

- display

-- I've played with the basic types of displays like ST7789

-- I would prefer a screen that's about 1 1/2 inches (38 mm) in diagonal

-- I would love high pixel density, but I don't know what I could use or the downsides