Pro Mini - usb power/serial port connection detection

Gents, i saw a few threads here and on stackexchange (http://arduino.stackexchange.com/questions/438/how-does-this-code-line-detect-if-a-serial-interface-is-connected) about proper detection of usb/serial connection/communication.

They all (seemed) to be related to UNO models, but i have a Pro Moni. I'm powering it either using a battery ( over power module) on VCC or by USB ( over FTDI module).

In a larger scope i'd like to detect if the Pro is connected to PC (over FTDI/USB) or just powered from a battery.

Since both power sources connect to VCC pins, i think there maybe a way to check something on FTDI side and work in reverse from there - if FTDI.XYZ == ON then you are not on battery. Appreciate your help.

Since both power sources connect to VCC pins, i think there maybe a way to check something on FTDI side and work in reverse from there - if FTDI.XYZ == ON then you are not on battery.

You don't have access to anything outside of the AtMega328 chips, including how the device is powered.

Thank you Paul, i guess i'd have to just assume that i'm always on battery.