Are you going to a dance party soon? Or maybe a speed dating night? Would you like to wear your heart out?
In this project, you can visibly show off your heart rate in the form of a pulsing pendant. A Circuit Playground Bluefruit (CPB) connects to a heart rate monitor to display the heartbeat of the wearer. Using the CircuitPython programming language, the CPB blinks with red NeoPixels to display the heart rate.
Heart Rate Monitor
You'll need a heart rate monitor that supports Bluetooth Low Energy (BLE). I'm using the Scosche RHYTHM+ but you should be able to use any monitor that uses the Bluetooth SIG Heart Rate service standard.
These work by flashing green (and sometimes yellow) LEDs against your skin and then measuring the reflected light that returns. The color changes/darkens during the pulse of your heart thanks to all that blood sloshing around!
Option 1: you can use a small Lithium Ion Polymer or "Lipo" battery and affix it to the back of the CPB.
Option 2: If you want to avoid lipos, you can use x3 AAA batteries with a battery back to get the same 3.7V to power the CPB.
There's a great case for the CPB that also works for the Circuit Playground Express (CPX). It is not required for this project but helps to make the NeoPixels a little more glowy and provides protection for the electronics.