A polling method, apparatus, and system to detect the attachment and detachment
of Universal Serial Bus devices in a wireless system. A hub provides a wired connection
to the host and wireless attachment points for its devices. The host periodically
queries the hub for changes in the hub's status register by sending a polling message
through each of its wireless ports, and awaits a response. A peripheral device
that wishes to attach to the system responds by sending its unique peripheral address.
If a device currently occupies the port, the hub sends out the device's unique
address in the polling message. If the device is still present, it responds by
sending its unique peripheral address. If a response is not received after multiple
retries, the device is considered detached. The hub thus determines the status
of the ports and updates the status register, which is queried by the host.
