Comment by thot_experiment

The heart rate is calculated manually by counting 20 heartbeats and using the timer.

Here are a couple (and I recall one other project but I can't remember the name of it right now) open source alternatives for those who aren't trying to fw a proprietary app/closed source system.

https://github.com/joeycastillo/Sensor-Watch https://github.com/PegorK/F91_Kepler