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.