Use a heart rate monitor and Feather nRF52840 together to display hear rate BPM and training zone percentage. John Park Learn Guide coming soon.
Visit the Adafruit shop online - http://www.adafruit.com
LIVE CHAT IS HERE! http://adafru.it/discord
Adafruit on Instagram: https://www.instagram.com/adafruit
Subscribe to Adafruit on YouTube: http://adafru.it/subscribe