Datasheet

If you open up an application on your mobile device or laptop that support the standard Heart Rate Monitor

Service (https://adafru.it/f4I), you should be able to see the heart rate being updated in sync with the changes seen in

the Serial Monitor:

nRF Toolbox HRM Example

The image below is a screenshot from the free nRF Toolbox (https://adafru.it/e9M) application from Nordic on Android

(also available on iOS (https://adafru.it/f4J)), showing the incoming Heart Rate Monitor data: