Power Management Contracts for Accessory Devices

• US 20150331463A1
• Filed: 05/19/2014
• Published: 11/19/2015
• Est. Priority Date: 05/19/2014
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Obie, Gene Robert, Huang, Heng, He, Yi, Evans, Duane Martin
• Granted Patent: US 9,874,914 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 1/1632 External expansion units, e.g. docking stations
• CPC Class Codes: G06F 1/266 Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips
• CPC Class Codes: G06F 21/44 Program or device authentication

Abstract

Power management contracts for accessory devices are described. In one or more implementations, a power management contract is established for a system including a host computing device and an accessory device based at least in part upon power exchange conditions observed for the system. The power management contracts define operating constraints for power exchange between components of the system, including at least a power exchange direction and current limits. The host computing device and accessory devices are each configured to renegotiate the power management contract to dynamically change operating constraints in “real-time.” Additionally, different power management contracts may be associated with identifying data corresponding to different types of accessory devices.

Claims

1. A method implemented by a host computing device comprising:

detecting connection of an accessory device to the host computing device via an accessory interface;

obtaining data indicative of an identity of the accessory device;

determining based on the data indicative of the identity whether the accessory device is an authorized accessory; and

when the accessory device is an authorized accessory, setting a default power contract for power exchange with the accessory device established based on the identity, including;

looking-up power contract settings associated with the accessory device; and

setting a power exchange direction and current limits according to the power contract settings;

2. A method as described in claim 1, further comprising monitoring to detect indications of power contract changes.

3. A method as described in claim 2, wherein the indications of power contract changes comprise power contract update messages communicated by the accessory device in response to power exchange conditions observed at the accessory device.

4. A method as described in claim 3, wherein power exchange conditions at the accessory device comprise power loads associated with one or more peripheral devices connected to the accessory device.

5. A method as described in claim 3, further comprising:

responsive to receiving a power contract update message communicated by the accessory device, updating the power exchange direction and current limits based on settings indicated by the power contract update message.

6. A method as described in claim 1, further comprising detecting an indication of a power contract change based on power exchange conditions observed at the host computing;

updating settings for the power exchange direction and current limits based on the indicated power contract change; and

sending a power contract update message to the accessory device to direct the accessory device to implement the updated settings.

7. A method as described in claim 1, further comprising:

when the accessory device is not an authorized accessory, restricting interaction with the accessory device.

8. A method as described in claim 1, wherein the accessory device comprises a docking station configured to facilitate connection of the host computing device to multiple peripheral devices.

9. A method as described in claim 1, wherein the data indicative of the identity of the accessory device comprises credentials supplied by the accessory device and determining whether the accessory device is an authorized accessory comprises authenticating the accessory device for power exchange with the host computing device by checking the credentials against known credentials for accessory devices authorized to exchange power with the host computing device.

10. A method as described in claim 9, wherein the credentials comprises a resistor value of a resistor associated with the accessory device.

11. A method as described in claim 10, wherein multiple different types of accessory devices connectable to the host computing device have different resistor values used to distinguish between the different types of accessory devices.

12. A host computing device comprising:

one or more microcontrollers;

one or more computer-readable media storing instructions that when executed via the one or more microcontrollers cause the host computing device to perform operations including;

managing power exchange between the host computing device and an accessory device connected to the host computing device in accordance with settings for at least a power exchange direction and current limits defined by an active power management contract;

monitoring to detect conditions that prompt changes to settings of the active power management contract;

when power contract changes are prompted according to the monitoring, updating the settings for at least the power exchange direction and current limits in accordance with the detected conditions.

13. A host computing device as described in claim 12, wherein the instructions are implemented via firmware corresponding to the one or more microcontrollers of the host computing device and the one or more microcontrollers are configured to operate independently of a primary processing system of the host computing device.

14. A host computing device as described in claim 12, wherein the accessory device includes a peripheral device hub and the conditions that prompt changes include a change in a number of peripherals devices attached to the peripheral device hub that causes an adjustment to the current limits.

15. A host computing device as described in claim 12, wherein the current limits comprises a maximum for power delivery from the accessory device to the host computing device.

16. A host computing device as described in claim 12, wherein the one or more microcontrollers include a power controller configured to enforce power contracts established between the host computing device and the accessory device to dynamically adjust the direction of power exchange and current limits based upon power exchange conditions observed at the host computing device and accessory device including at least relative states of charge, power loads, and power source availability.

19. An accessory device as recited in claim 16, wherein the power exchange conditions include at least a power load supplied by the accessory device to power peripheral devices connected via the accessory device.

20. An accessory device as recited in claim 16, wherein the power exchange conditions include at least an amount of power available to the accessory device via internal and external power supplies.

17. An accessory device comprising:

one or more hardware elements;

one or more modules that when executed via the one or more hardware elements cause the accessory device to perform operations including;

supplying data to a host computing device indicative of an identity of the accessory device;

exchanging power with the host computing device in accordance with active settings for current limits and exchange direction associated with the identity;

monitoring power exchange conditions at the accessory device;

when power contract changes are prompted according to the monitoring;

communicating a power contract update message to the host device to adjust the active settings, the power contract update message specifying values for the exchange direction and current limits based on the power exchange conditions observed by the monitoring;

subsequently exchanging power with the host computing device in accordance with adjusted settings for current limits and exchange direction.

18. An accessory device as recited in claim 17, wherein supplying the data indicative of the identity of the accessory device comprises exposing a resistor value indicative of the identity for reading by the host computing device.