Method of maintaining a USB active state without data transfer
First Claim
1. An on-demand method of powering a USB device, comprising:
- supplying a first current to a USB device attached to a USB bus segment in active mode;
in response to a lack of USB data transfer activity at the USB device, placing the USB bus segment in suspend mode and supplying a second current lower than the first current to the USB device;
in response to an indication from the USB device, restoring the USB bus segment to active mode and supplying the first current to the USB device;
wherein the USB bus restore does not prompt a data transfer between a USB host and the USB device.
3 Assignments
0 Petitions
Accused Products
Abstract
A USB bus-powered device in Suspend state that requires active bus state power levels, but has no data transfer need, may initiate Resume signaling to return a USB bus segment to active state, without transferring any data across the bus. A device driver considers both USB device power needs and data transfer activity in deciding to Globally or Selectively Suspend a bus or bus segment. In particular, upon deciding to Suspend a bonus or bus segment, the device driver queries a USB bus-powered device. If the device will require active bus mode power within a predetermined duration, the device will indicate to the device driver to remain an active mode. In this case, the device driver does not direct the USB host to Suspend the bus.
39 Citations
15 Claims
-
1. An on-demand method of powering a USB device, comprising:
-
supplying a first current to a USB device attached to a USB bus segment in active mode; in response to a lack of USB data transfer activity at the USB device, placing the USB bus segment in suspend mode and supplying a second current lower than the first current to the USB device; in response to an indication from the USB device, restoring the USB bus segment to active mode and supplying the first current to the USB device; wherein the USB bus restore does not prompt a data transfer between a USB host and the USB device. - View Dependent Claims (2, 3, 4)
-
-
5. A USB bus-powered device, comprising:
-
an electronic circuit; a USB interface receiving from a USB bus segment a first current sufficient to power the electronic circuit in an active mode and a second current insufficient to power the electronic circuit in a suspend mode; and a controller operative to anticipate a need to power the electronic circuit, and in response, to issue a remote wakeup procedure to transition the USB bus segment from suspend mode to active mode without transferring data across the USB bus. - View Dependent Claims (6, 7)
-
-
8. A data processing system, comprising:
-
a processor; a USB bus host controlling at least one USB bus segment; at least one USB bus-powered device drawing current from the USB bus; and a computer readable medium including instructions in the form of a device driver operative to execute on the processor and cause the computer to monitor device activity and selectively direct the USB bus host to suspend the USB bus segment, the device driver further operative to cause the computer to query the USB bus-powered device for power needs prior to suspending the USB bus segment. - View Dependent Claims (9, 10, 11, 12, 13)
-
-
14. A computer readable medium including instructions in the form of a USB device driver, the instructions operative to cause a computer to perform the steps of:
-
monitoring a USB bus segment for data transfer activity; determining, based on a lack of data transfer activity, to suspend the bus segment; querying one or more devices attached to the bus segment whether they can enter a low power mode; and selectively suspending the bus segment or not, in response to the a device'"'"'s response to the query. - View Dependent Claims (15)
-
Specification