This project is intended to be paired with https://www.thingiverse.com/thing:3406844
I built mine using an Adafruit 2.4" TFT FeatherWing, Adafruit Feather nRF52 Bluefruit LE -nRF52832, and a 400mAh Lipo battery.
Links: https://www.adafruit.com/product/3315 https://www.adafruit.com/product/3406 https://www.adafruit.com/product/3898
Please buy them from Adafruit if you can. They do great stuff, provide support, and are awesome folks.
This project is ROUGH around the edges, as my C skills are rusty at best. So other boards or displays may not work.
Version 1 starts out our capacity bars at some value, then exponentially decays them. Version 2 will do a better job and change the color from blue (100%-50%), Yellow (50%-25%), Red (bellow 25%).
If you ar curious the text is AL=Activity Level, BR=Breathing Rate, ST=?, HR=Heart Rate, 02=Oxygen.
You will need to make sure that your Arduino IDE has the support for your board setup: for the nrf52 board: https://learn.adafruit.com/bluefruit-nrf52-feather-learning-guide/arduino-bsp-setup
And install the required Libraries: Adafruit GFX Adafruit ILI9341 gfxfont