i have been wondering for a while now how i could make an application that is like the bluetooth voltmeter., but is capable of reading other sensors and sending the information to a gui interface or app? i saw someone who used the headset input as a voltmeter with an app but i figure it would have to be through usb . power shoulldnt travel through the headset port but i have had chargers were it connected to the headset port? what is the reason for this?