Method for automatically switching USB peripherals between USB hosts
A system for automatically switching peripheral connectivity between two host devices based on respective connectivity of the hosts. The method may be used where peripherals are usually attached to one host and are automatically switched to a second host when the second host is attached to the system. A USB switching hub may be operable to automatically switch connectivity of the peripheral device(s) from the first host device to the second host device when the second host device is connected to the USB device. This automates the process for the end user when normally all peripherals are attached to one host, and some or all peripherals are shared with a second host when the second host is attached.
1. A system, comprising:
a USB hub;
a first host device coupled to the USB hub;
a plurality of peripheral devices coupled to the USB hub;
a second host device operable to be coupled to the USB hub;
wherein the USB hub is operable to provide connectivity between the first host device and the plurality of peripheral devices when the first host device is connected to the USB hub and the second host device is not connected to the USB device;
wherein the USB hub is operable to automatically provide connectivity between the second host device and one or more of the plurality of peripheral devices when the second host device is connected to the USB hub, wherein the USB hub is configured to maintain connectivity between the first host device and remaining ones of the plurality of peripheral devices that were not provided connectivity to the second host device.
2. The system of claim 1 ,
wherein the USB hub is operable to automatically remove connectivity between the first host device and the one or more of the plurality of peripheral devices when the second host device is connected to the USB hub.
3. The system of claim 1 ,
wherein the USB hub is included in a display device.
4. The system of claim 1 ,
wherein the first host device is a computer system.
5. The system of claim 1 , wherein the USB hub comprises:
a plurality of upstream ports;
a plurality N of downstream ports; and
downstream switching logic coupled between the plurality of upstream ports and the plurality of downstream ports;
wherein the downstream switching logic is configured to electronically switch communications between:
a) a downstream port of the plurality of downstream ports and a first upstream port of the plurality of upstream ports to
b) the downstream port of the plurality of downstream ports and a second upstream port of the plurality of upstream ports.
6. The system of claim 5 ,
wherein the USB hub is configured to be enumerated with a substantially similar hub configuration through each of the plurality of upstream ports;
wherein the hub configuration includes N downstream ports.
7. A USB hub comprising:
a first input for coupling to a first USB host device;
a second input for coupling to a second USB host device;
a plurality of peripheral device inputs for coupling to respective ones of a plurality of peripheral USB devices;
switching logic that is operable to provide connectivity between the first input and the plurality of peripheral device inputs when the first USB host device is connected to the first input and the second USB host device is not connected to the second input;
wherein the switching logic is operable to automatically provide connectivity between the second input and one or more of the plurality of peripheral device inputs when the second USB host device is connected to the second input, wherein the switching logic is configured to maintain connectivity between the first input and remaining ones of the plurality of peripheral device inputs that were not provided connectivity to the second input.
8. The USB hub of claim 7 ,
wherein the USB hub is operable to select from a plurality of connectivity configurations to determine how each of the plurality of peripheral USB devices is coupled to the first input and/or the second input.
9. The USB hub of claim 8 , further comprising a memory element coupled to the USB hub, wherein the memory element is configured to store the plurality of connectivity configurations.
10. The USB hub of claim 8 , wherein the USB hub comprises a plurality of control input signals, wherein a combination of a state of each of the plurality of control input signals determines which of the plurality of connectivity configurations is selected.
11. The USB hub of claim 10 , wherein the second input comprises a power connection coupled to one of the plurality of control input signals, wherein the power connection changes states when the second USB host device is coupled to the second input;
wherein one or more of the plurality of peripheral devices are coupled to the second input in response to the power connection changing states, according to a selected one of the plurality of connectivity configurations.
12. The USB hub of claim 11 , wherein a combination of a state of each of remaining ones of the plurality of control input signals determines the selected one of the plurality of connectivity configurations.
13. The USB hub of claim 8 , wherein the USB hub comprises a plurality of control lines, each one of the plurality of control lines corresponding to a respective one of the plurality of peripheral USB devices,
wherein a respective state of each of the plurality of control lines determines whether its corresponding respective one of the plurality of peripheral USB devices couples to the first input and/or the second input.
14. The USB hub of claim 13 , wherein a default state of each of the plurality of control lines is configured to couple its corresponding respective one of the plurality of peripheral USB devices to the first input.
15. The USB hub of claim 14 , wherein the second input comprises a power connection, wherein each of the plurality of control lines is coupled to the power connection through a respective switch;
wherein the power connection changes states when the second USB host device is coupled to the second input; and
wherein a position of each switch determines whether its corresponding respective one of the plurality of control lines changes states, in response to the power connection changing states.
16. The USB hub of claim 15 , wherein the default state is a low state, and wherein a high state of each of the plurality of control lines is configured to couple its corresponding respective one of the plurality of peripheral USB devices to the second input;
wherein in changing states the power connection is driven to a high state from a low state.
17. A method for operating a USB device, the method comprising:
coupling a plurality of peripheral device inputs of the USB device to respective ones of a plurality of peripheral USB devices;
coupling a first input of the USB device to a first USB host device;
providing connectivity between the first input and the plurality of peripheral device inputs when the first USB host device is connected to the first input and a second USB host device is not connected to a second input of the USB device;
coupling the second input of the USB device to a second USB host device;
automatically providing connectivity between the second input and one or more of the plurality of peripheral device inputs when the second USB host device is connected to the second input; and
maintaining connectivity between the first input and remaining ones of the plurality of peripheral device inputs that were not provided connectivity to the second input.
18. The method of claim 17 , further comprising automatically removing connectivity between the first input and the one or more of the plurality of peripheral device inputs when the second USB host device is connected to the second input.
19. The method of claim 17 , further comprising selecting from a plurality of connectivity configurations to determine how each of the plurality of peripheral USB devices is coupled to the first input and/or the second input.
20. The method of claim 19 , further comprising storing the connectivity configurations, wherein said selecting from a plurality of connectivity configurations comprises selecting from the stored connectivity configurations.
21. The method of claim 19 , further comprising performing said selecting from a plurality of connectivity configurations according to a combination of a state of each of a plurality of control input signals.