Patent Application
20060059293
1. Field of the Invention
The present invention relates generally to peripheral device hubs and, more specifically, to Universal Serial Bus (USB) switching hubs.
2. Description of the Related Art
The Universal Serial Bus (USB) allows coupling of peripheral devices to a computer system. USB is a serial cable bus for data exchange between a host computer and a wide range of simultaneously accessible devices. The bus allows peripherals to be attached, configured, used, and detached while the host is in operation. For example, USB printers, scanners, digital cameras, storage devices, card readers, etc. may communicate with a host computer system over USB. USB based systems may require that a USB host controller be present in the host system, and that the operating system (OS) of the host system support USB and USB Mass Storage Class Devices.
USB devices may communicate over the USB bus at low-speed (LS), full-speed (FS), or high-speed (HS). A connection between the USB device and the host may include four wires (a power line, a ground line, and a pair of data lines (D+ and D−). When a USB device connects to the host, the USB device may first pull a D+ line high (the D− line if the device is a low speed device) using a pull up resistor on the D+ line. The host may respond by resetting the USB device. If the USB device is a high-speed USB device, the USB device may “chirp” by driving the D− line high during the reset. The host may respond to the “chirp” by alternately driving the D+ and D− lines high. The USB device may then electronically remove the pull up resistor and continue communicating at high speed. When disconnecting, full-speed devices may remove the pull up resistor from the D+ line (i.e., “tri-state” the line), while high-speed USB devices may tri-state both the D+ and D− lines.
A USB hub may be coupled to a USB host controller to allow multiple USB devices to be coupled to the host system through the USB host controller. In addition, other USB hubs may be coupled to the USB hub to provide additional USB device connections to the USB host controller.
Some dual role peripheral devices may include a slave controller and be capable of communicating with other peripheral devices coupled to them. For example, a dual role USB printer may be able to communicate directly with a USB camera to print pictures from the USB camera. The dual role USB printer may also be accessible (e.g., by a computer system) as a slave peripheral device. If a computer system and dual role peripheral device need to alternately access a peripheral device, the peripheral device may need to be unplugged from one device and coupled to the other. Prior art device switches may not work for high-speed peripheral devices. For example, mechanical switches may introduce too much capacitance or inductance to work with high-speed peripheral devices. High-speed peripheral devices also typically require smooth impedance to prevent ringing (mechanical switches introduce irregularities in the impedance that may cause ringing).
In various embodiments, a USB switching hub may control access between two or more upstream ports on the USB switching hub and at least a subset of downstream ports on the USB switching hub. The USB switching hub may electronically switch between different configurations (e.g., hardwired or software implemented configurations) for access between the two or more upstream ports and the downstream ports. In an embodiment with two upstream ports and three downstream ports, a USB switching hub may switch between multiple configurations. For example, in a first configuration, the first upstream port may be allowed access to the first two downstream ports and the second upstream port may be allowed access to the third downstream port. In a second configuration, the first upstream port may be allowed to access the third downstream port while the second upstream port may be allowed to access the first two downstream ports. Other configurations are also possible (e.g., in one configuration neither upstream port may be allowed to access any downstream port). The USB switching hub, after receiving a control signal (e.g., from a computer, a different attached device, a person, a sensor, etc.), may switch between the first configuration and the second configuration (or another configuration). The control signal may be generated internal to the USB switching hub (e.g., by logic internal to the USB switching hub). In some embodiments, the USB switching hub may not receive a control signal before switching configurations.
In some embodiments, a computer system and a dual role peripheral device (e.g., a dual role USB printer or dual role USB Digital Versatile Disc (DVD) read/write drive, among others) may be coupled to upstream ports of a USB switching hub. Other devices and/or systems (e.g., another computer system) may be coupled to the upstream ports. The dual role peripheral device may interface with other peripheral devices (e.g., downstream peripheral devices) through its host controller and/or may interface with other devices (such as the computer system) as a peripheral device itself.
In some embodiments, the upstream ports may be coupled to a downstream routing controller through one or more hub controllers. The downstream routing controller may switch between different configurations for the two or more upstream ports and the downstream ports (e.g., when triggered by a control signal). In some embodiments, the downstream routing controller may be coupled to the downstream ports through transaction translator circuitry. In some embodiments, the peripheral devices (as well as the dual role peripheral device) may be coupled through interfaces (e.g., a USB Physical Layer (PHY) interface, USB Transceiver Macrocell Interface (UTMI), or UTMI plus low pin interface (ULPI), among others) to the downstream ports. In some embodiments, configurations (e.g., hardwired in the USB switching hub) may be switched as determined by logic on the USB switching hub. Other configuration implementations are also contemplated.
A better understanding of the present invention may be obtained when the following detailed description is considered in conjunction with the following drawings, in which:
a and 4b illustrate two configurations of the USB switching hub, according to an embodiment;
a, 5b, and 5c illustrate additional configurations of the USB switching hub, according to an embodiment;
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. Note, the headings are for organizational purposes only and are not meant to be used to limit or interpret the description or claims. Furthermore, note that the word “may” is used throughout this application in a permissive sense (e.g., having the potential to or being able to in some embodiments), not a mandatory sense (i.e., must). The term “include”, and derivations thereof, mean “including, but not limited to”. The term “coupled” means “directly or indirectly connected”.
In some embodiments, the USB switching hub 119 may have multiple downstream ports 121 for coupling to multiple peripheral devices 125. Peripheral devices 125 may include USB printers, scanners, digital cameras, digital camera docks, consumer audio/video, storage devices, and card readers, among others. In some embodiments the peripheral devices 125 may couple to the USB switching hub 119 through an interface 123. In some embodiments, the interface 123 may be a PHY interface. Other interfaces may also be used (e.g., UTMI or ULPI). The upstream ports 117 and downstream ports 121 may also have interfaces.
In some embodiments, a dual role peripheral device 207 may include a dual role USB printer or dual role USB Digital Versatile Disc (DVD) read/write drive, among others. In some embodiments, the dual role peripheral device 207 may be coupled to an upstream port (e.g., upstream port 117b) of the USB switching hub 119 through device port 210. The dual role peripheral device 207 may interface through the upstream port 117b with other peripheral devices (downstream peripheral devices) coupled to the USB switching hub 119 (e.g., using a host controller 209 on the dual role peripheral device 207). The dual role peripheral device 207 may also interface with other upstream devices (such as the computer system 101) through a slave controller. For example, the dual role peripheral device 207 may be coupled to the USB switching hub 119 as a slave peripheral device (e.g., through a downstream port 121c). In some embodiments, the dual role peripheral device 207, coupled to the USB switching hub, may simultaneously act as a host to one or more peripheral devices and/or as slave peripheral device to a separate host.
In some embodiments, the dual role peripheral device 207 may have an embedded host controller application to operate as a standalone system (e.g., to communicate with another peripheral device, such as a digital camera, without PC intervention). For example, a dual role USB printer may print pictures directly from a digital camera, coupled to a downstream port 121 on the USB switching hub 119, without PC intervention. In some embodiments, the USB switching hub 119 may alternately allow the computer system 101 or the dual role peripheral device 207 to access one or more downstream devices (e.g., by switching between one or more configurations).
a illustrates an embodiment of a computer system electronically coupled to multiple peripheral devices. In some embodiments, the USB switching hub 119 may act like a switch coupling multiple internal “hubs” that may share one or more downstream ports. For example, each potential configuration of the USB switching hub may represent an internal “hub”. In some embodiments, when the computer system 101 is accessing a peripheral device 125 (e.g., peripheral device 125a) coupled to the USB switching hub 119, communications to/from the peripheral device may be processed through a first “hub” comprised of first upstream port 117a, hub controller 203a, transaction translator 205, and at least a subset of the downstream ports 121. A second “hub” may be comprised of a second upstream port 117b, hub controller 203b, transaction translator 205, and at least a subset of the downstream ports 121. In one configuration, the computer system 101 may connect to downstream ports 121a and 121c (through the first “hub”), and the dual role peripheral device 207 may connect to downstream ports 121b and 121d (through the second “hub”) (as seen in
In some embodiments, the computer system 101 and the dual role peripheral device 125 may communicate through the USB switching hub 119 simultaneously with separate downstream devices. For example, while the computer system 101 communicates with device 125a (e.g., through the first “hub”), the dual role peripheral device 207 may communicate with device 125b (e.g., through the second “hub”). In some embodiments, while the peripheral device 125a is being accessed through the first “hub”, a different upstream device may not be able to access peripheral device 125a (e.g., dual role peripheral device 207 may not be able to access peripheral device 125a while peripheral device 125a is being used by computer system 101). In some embodiments, a signal (e.g., from an external control block) may trigger the downstream routing controller 201 to switch access for a subset of downstream ports 121 (e.g., downstream port 121a and/or 121c) on the first “hub” to the second “hub” (i.e., switch configurations).
In some embodiments, the dual role peripheral device 207 may send a control signal to the USB switching hub 119. The USB switching hub may then switch configurations to connect one or more downstream ports to the dual role peripheral device. For example, when a user presses a button on a dual role peripheral device 207 (e.g., a dual role printer), a signal may be sent through mode 211 to the downstream routing controller 201 to switch access of the device 125a from the computer system 101 to the dual role peripheral device 207 (i.e., to switch to a second configuration as seen in
In some embodiments, when activity is no longer detected between the dual role peripheral device 207 and a downstream port (e.g., if the dual role peripheral device 207 is turned off), the downstream routing controller 201 may switch access of the downstream port to the computer system 101 (i.e., switch to a different configuration). In some embodiments, the downstream routing controller 201 may switch access of the downstream port to a different upstream device. In some embodiments, instead of detecting inactivity, a signal from the dual role peripheral device 207 may signal the USB switching hub 119 to switch. Other signals and/or logic may also be used in determining when to switch configurations.
In some embodiments, configurations may be software implemented. In some embodiments, a microprocessor coupled to or comprised in the downstream routing controller 201 may dynamically determine, e.g., using a dynamic configuration profile, which downstream ports to electrically couple to each upstream port. For example, the microprocessor may read a stored configuration profile and attempt to connect upstream ports to downstream ports according to the configuration profile. The configuration profiles may be stored on a memory (e.g., an Electronically Erasable Programmable Read-Only Memory (EEPROM)) coupled to the USB switching hub 119. In some embodiments, hub controllers on the USB switching hub may have access to the configuration profiles.
In some embodiments, a priority logic may be used to switch configurations. Priority logic, or other logic used to grant access, may be internal or external to the USB switching hub 119. In some embodiments, a computer system 101 may be given priority over all of the downstream ports until an external control signal is sent from the dual role peripheral device 207 to switch access of one or more downstream ports to the dual role peripheral device 207. In some embodiments, different control signals may be sent to trigger different configurations (i.e., to switch access of different downstream ports to the dual role peripheral device 207).
In some embodiments, host negotiation logic may be used to determine which configuration to use. In some embodiments, a default configuration may be used until multiple upstream devices “request” access to the same downstream port. Host negotiation logic may be used to determine which configuration to use (i.e., which configuration gives a particular upstream port access to the “requested” downstream port).
In some embodiments, a microprocessor in the USB switching hub 119 may include a built in algorithm that auto detects downstream peripheral devices and determines how to connect the downstream peripheral devices. For example, instead of assigning a specific downstream port to an upstream port, a configuration profile may specify that the upstream port should have access to a digital camera if one is attached. The built in algorithm may auto-detect the digital camera when it is attached to one of the downstream ports and attach it to the appropriate upstream port (i.e., by switching to an appropriate configuration).
In some embodiments, when the downstream routing controller 201 switches configurations, and control of a downstream port is switched from the computer system 101 to the dual role peripheral device 207, a connection between the computer system 101 and the respective peripheral device 125 (coupled to the downstream port to be switched) may be terminated by the computer system 101. In some embodiments, communications between the downstream port to be switched and the computer system 101 may be terminated by the USB switching hub 119. The dual role peripheral device 207 may then connect to, enumerate, and communicate with the respective peripheral device 125 coupled to the switched downstream port.
Upstream devices may see downstream ports that they are not configured to attach to as unattached ports (i.e., active, but with no device connected). In some embodiments, if only a predetermined number of downstream ports is ever going to be attached to a particular upstream port (e.g., a number “x” ports), the upstream device may be signaled that the hub only has x ports. For example, if upstream port 117b is only going to be configured to attach to downstream ports 121c and 121d, a device attached to upstream port 117b may be signaled that the USB switching hub 119 is only a two port hub.
a, 5b, and 5c illustrate various embodiments of a computer system 101 and two dual role peripheral devices coupled to the USB switching hub 419. In some embodiments, multiple dual role peripheral devices may be coupled to the USB switching hub 419. For example, a dual role printer 407 may be coupled to the USB switching hub 419 through upstream port 417b and a dual role DVD read/write drive 467 may be coupled to the USB switching hub 419 through upstream port 417c. Computer system 101 may be coupled to the USB switching hub 419 through upstream port 417a. Each of the upstream devices may be coupled to a respective hub controller 403, downstream routing controller 401, and transaction translator 405. Downstream routing controller 401 may configure communications between each of the upstream devices (i.e., the computer system 101, the dual role printer 407, or dual role DVD read/write drive 467) and at least a subset of the peripheral devices 425.
As seen in
In some embodiments, transaction translator(s) in the USB switching hub (e.g., USB switching hub 419 or USB switching hub 519) may allow upstream ports to communicate at different communication speeds relative to the other upstream ports. For example, one upstream port may be coupled only to high speed devices and, therefore, communicate at high speed, while a separate upstream port may be coupled to only full speed devices and, therefore, communicate at full speed. In some embodiments, upstream ports may be able to communicate with different downstream ports at different speeds because of the transaction translators.
At 701, the USB switching hub may receive a signal (e.g., an external control signal) signaling the USB switching hub to switch between a first configuration and a second configuration. For example, switching configurations may switch access of a first downstream port from a first upstream port to a second upstream port. In some embodiments, a user may press a button on a dual role peripheral device coupled to the USB switching hub, and the dual role peripheral device may send an external control signal to the USB switching hub to signal the USB switching hub to switch between one or more configurations. In some embodiments, the signal may be internal (e.g., generated by logic internal to the USB switching hub).
At 703, communication between a host coupled to the first upstream port and the first peripheral device coupled to the first downstream port may be terminated. In some embodiments, communication may be terminated for a subset of the downstream peripheral devices.
At 705, the USB switching hub may switch between the first configuration and the second configuration to give access of the first downstream port to the second upstream port. In some embodiments, the configuration switch may affect access for a subset of the downstream peripheral devices.
At 707, the downstream peripheral device coupled to the first downstream port may be accessed through the second upstream port by the host coupled to the second upstream port. In some embodiments, the second upstream port may communicate with a subset of the downstream peripheral devices. For example, the host may enumerate and then communicate with the switched multiple downstream devices. In some embodiments, access between the first upstream port and a second downstream port may continue.
Further modifications and alternative embodiments of various aspects of the invention may be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.
