-The first item holds the data/time when the readings were taken and the file is deleted each time the app is run.
-The hrm sensor is sampled @50Hz and this app does not do any processing on it other than clip overly high/extreme values, the array is written as-is. There is an example Python script that can process this signal, smooth it and also extract a myriad of heart rate variability metrics using the hrvanalysis library: