US 2015/0309954 A1Published application

Apparatus and methods for dynamic role switching among usb hosts and devices

AssigneeMCCI Corporation

InventorTerrill M. Moore

Life of this patent

Estimating the term…

Loading patent…

Abstract

Apparatus and methods for USB hosts and USB devices to dynamically switch roles such that a product which initially operates as a USB host may instead operate as a USB device and vice versa. Products such as smartphones and tablets which initially operate as USB devices may dynamically switch roles to become USB hosts. Similarly, products such as PCs and in-vehicle infotainment systems which initially operate as USB hosts may dynamically switch roles to become USB devices. Dynamic USB role switching is permitted in a variety of topologies including those in which a direct connection exists between a host and a device as well as those in which a USB hub is present. In addition, such dynamic role switching may be performed in topologies which incorporate widely used USB Type A connectors and cables, thus avoiding the need for a special connector or cable.

Claims20

Dependent claims

A method for switching roles between an initial Universal Serial Bus (USB) host and an initial USB device such that the initial USB host becomes a role-switched USB device and the initial USB device becomes a role-switched USB host, the method comprising:

maintaining, by the initial USB host, a USB host stack in a USB host stack active state, a USB device stack in a USB device stack idle state, and a root port operating as a USB host;
maintaining a connection between the initial USB host and the initial USB device;
determining, by the USB host stack, that the initial USB device is capable of switching roles based on device descriptor information associated with the initial USB device;
sending, by the USB host stack, a role switch root port message to the root port;
sending, by the root port, a detach message to the USB host stack in response to receiving the role switch root port message;
detaching the root port from the USB host stack;
sending, by the root port, an activate message to the USB device stack to cause the USB device stack to transition to a USB device stack active state;
transitioning the USB host stack to a USB host stack idle;
using the USB device stack to enable the root port to attach to the initial USB device such that that the initial USB host becomes the role-switched USB device and the initial USB device becomes the role-switched USB host;
and
using the role-switched USB host to control the role-switched USB device.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/699,558Filed 29 Apr 2015
Priority: 29 Apr 2014
Published: 29 Oct 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G06F 13/4022
Coupling between buses: using switching circuits, e.g. switching matrix, connection or expansion network
G06F 13/382
Information transfer, e.g. on bus: using universal interface adapter
G06F 13/426
On a daisy chain bus: using an embedded synchronisation, e.g. Firewire bus, Fibre Channel bus, SSA bus
G06F 13/4045
Using bus bridges: where the bus bridge performs an extender function