given that you can buy these for < $20us delivered to your door i doubt its worth while making them other than as an intellectual exercise
https://au.banggood.com/BOXYM-oFit-2...r_warehouse=CN
i have tried the sparkfun arduino demos and was not particularly impressed with accuracy or stability of readings obtained
{maybe my heart is inaccurate and unstable}
the raspberrypi code goes about it quite differently&nbsp; with some dsp done on data collected in a fixed sampling period [not tried it].
i have no experience with these things , i don't know if reverse engineering the arduino code is even worthwhile
but no matter how you go about it the sort of digital signal processing needed will be lots and lots of hard work with pbp
do you have a plan ? have you established optimal device settings to get the best readings ? how much data is needed and from where ?
reading and writing to the device is child's play, setting it up to get meaningful data and being able to extract information from that data is another story