US 2018/0024954 A1 · APPARATUS AND METHODS FOR DYNAMIC ROLE SWITCHING AMONG USB HOSTS AND DEVICES

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 comprising:

connecting an initial Universal Serial Bus (USB) host to an initial USB device, the initial USB host having (i) a USB host stack in a first active state, (ii) a USB device stack in a first idle state, and (iii) a root port operating as a USB host;
evaluating device descriptor information associated with the initial USB device to determine that the initial USB device is capable of switching roles;
issuing a role switch root port message from the USB host stack to the root port;
transitioning the USB device stack from the first idle state to a second active state in response to an activate message from the root port to the USB device stack;
transitioning the USB host stack from the first active state to a second idle state;
enabling the root port to attach to the 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;
and
controlling the role-switched USB device using the role-switched USB host.

5 more elements

Dependencies are inferred from the claim text.

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

Life of this patent

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

Life of this patent

Abstract

Claims20