The code snippet below detects Power on the USB Port of WatchX.
An data connection to an computer is not needed.
Put in Setup:
USBCON|=(1<<OTGPADE); //enables VBUS pad
Use in Loop:
if(USBSTA&(1<<VBUS)) {Code on USB Power is on}
or
bool usbConnected = (USBSTA&(1<<VBUS));