How do I make an HR-controlled PWM fan, using my Alta HR as a control input?

[423536271827]

It should work like this. The fan is off at 50% heart rate or less. When heart rate is 50% or higher, each 1% my HR increases or decreases, the fan's speed will increase/decrease by 2%. It should be at full speed when my HR is 100%. How do I do the PWM, and how do I turn off the fan with pin 4 when my heart rate is less than 50%? How do I get the live HR directly from a BT connection between the Alta HR and my Raspberry pi? 100% heart rate is calculated by subtracting your age from 220, and I already got the code to enter your age.

[Gordon-C]

Hi @423536271827 

All Fitbit devices do not support direct BT connectivity to a 3rd party device.  The only devices that support real-time access to the data are the smart watches (ionic, Versa family and Sense).   However, using the Device SDK with the smart watches, you can build a companion application which pulls the data from the Fitbit device over a "socket" connection.