Thanks Jan,
This link gave me hints, but, I did not manage to trig an event when connecting and disconnecting the usb cable. When I run "udevadm monitor", there is no event displayed upon cable connection or disconnection.
On my setup, the phyCore is the device, and I wish to detect when the PC (host) is connected or not. The detection is on the phyCORE side (linux embedded).
I have also been looking for a detection of the power USB from PC, found nothing yet.