Once set up, press the blue connect bluetooth button. If successful, a notification will confirm this across the top of the screen and logging will start automatically, shown by a green tick next to the ‘save’ icon in the top right of the screen.
The size of the logfile shown on top left of the screen will only update once logging is stopped.
To export the data, go to app settings and the first option is to share the data through whatever service you would like, as well as the option to clear the saved data.
Data is saved in a .csv file in the phone's downloads folder so can also be retrieved via a file manager app, or via a USB connection to a computer.