Power management in electronic devices

• US 8,762,746 B1
• Filed: 03/22/2011
• Issued: 06/24/2014
• Est. Priority Date: 03/22/2011
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Lachwani, Manish, Berbessou, David
• Primary Examiner(s): YANCHUS III, PAUL B
• Application Number:
  US13/069,297
• Time in Patent Office: 1,190 Days
• Field of Search: None
• US Class Current: 713/300
• CPC Class Codes: G06F 1/263 Arrangements for using multiple switchable power supplies, e.g. battery and AC G06F1/30 takes precedence
• 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

Abstract

Some implementations provide power management techniques for an electronic device that receives power through a USB port. The device may receive power from various different power sources such as a PC, USB hub, and various types of power adapters. To identify a type of power adapter connected to the USB port, the device'"'"'s USB device controller may be reconfigured to operate in a host mode. A pull-up or pull-down may be placed on one of the D+ or D− lines of the USB port for determining whether the lines are shorted or floating. When the lines are shorted, the power source may be identified as a first type of power adapter that provides a known level of current. When the lines are not shorted, the values of the lines may be compared with known values for one or more pull-ups or pull-downs to attempt to identify other known power adapters.

Claims

1. A device comprising:

a universal serial bus (USB) port having a D+ line and a D−

line;

a USB device controller configured to operate in a host controller mode and a device controller mode;

one or more processors operatively coupled to a computer readable medium; and

a power management module maintained on the computer-readable medium and executed on the one or more processors to perform operations including;

detecting that a power source is connected to the USB port;

based at least in part on determining that the D+ and D−

lines are at least one of shorted or floating, setting the USB device controller to operate in the host controller mode;

determining, based at least in part on a pull-up or pull-down placed on one of the D+ or D−

lines, whether the D+ and D−

lines are shorted or floating; and

when the D+ and D−

lines are shorted, identifying the power source as being a type of power adapter capable of providing a known level of current.

2. The device as recited in claim 1, the setting the USB device controller to operate in the host controller mode further comprising:

stopping the USB device controller while the USB device controller is configured to operate in the device controller mode; and

restarting the USB device controller in the host controller mode to enable the USB device controller to place the pull-up or pull-down on the one of the D+ or D−

lines.

3. The device as recited in claim 1, wherein:

the USB device controller further comprises a register indicating a state of the D+ and D−

lines when the power source is connected to the USB port; and

the power management module performing operations further comprising;

prior to setting the USB device controller to operate in the host controller mode, determining, at least in part from the register, that the D+ and D−

lines are indicated to be at least one of shorted or floating.

4. The device as recited in claim 3, the determining, at least in part from the register, that the D+ and D−

lines are indicated to be at least one of shorted or floating further comprising checking values of a pair of line status bits in the register.

5. The device as recited in claim 1, the power management module performing operations further comprising, when the D+ and D−

lines are floating, attempting to identify, based at least in part on at least one of the pull-up or pull-down on at least one of the D+ and D−

lines, a particular power adapter as the power source.

6. The device as recited in claim 5, the power management module performing operations further comprising referring to a power adapter information table to compare values of the D+ and D−

lines with values previously determined for known adapter models to attempt to identify the particular power adapter.

7. The device as recited in claim 5, the power management module performing operations further comprising, when the attempting to identify the particular power adapter fails, setting a level of current to be drawn from the power source to a default level of current, lower than the known level of current.

8. The device as recited in claim 1, further comprising a power management integrated circuit (PMIC), the PMIC configured to receive an instruction from the power management module for setting a level of current to be drawn from the power source based, at least in part, on the known level of current.

9. The device as recited in claim 1, wherein the determining whether the D+ and D−

lines are shorted or floating comprises determining that the D+ and D−

lines are shorted when the pull-up or pull-down placed on a first one of the D+ or D−

lines results in a second one of the D+ and D−

lines following the first one.

10. A method comprising:

under control of an electronic device configured with specific executable instructions and having a universal serial bus (USB) port,

connecting a power source to the USB port, the USB port including a D+ line and a D−

line;

based at least in part on determining that the D+ and D−

lines are at least one of shorted or floating, stopping a USB device controller operating in a client controller mode;

restarting the USB device controller in a host controller mode; and

applying a pull-up or pull-down on one of the D+ or D−

lines of the USB port to determine whether the D+ and D−

lines are shorted.

11. The method as recited in claim 10, further comprising,

prior to the stopping the USB device controller, accessing a register of the USB device controller;

and

determining, at least in part from the register, that the D+ and D−

lines are indicated to be at least one of shorted or floating.

12. The method as recited in claim 11, the determining, at least in part from the register, that the D+ and D−

lines are indicated to be at least one of shorted or floating further comprising checking values of a pair of line status bits in the register.

13. The method as recited in claim 10, further comprising:

prior to stopping the USB device controller, accessing a register of the USB device controller; and

determining, that the power source is not a host USB port on another device.

14. The method as recited in claim 10, further comprising, following a decision that the D+ and D−

lines are shorted, setting a current level to be drawn from the power source to a known current level.

15. The method as recited in claim 14, wherein the known current level is greater than or equal to 880 milliamps.

16. The method as recited in claim 10, further comprising, following a decision that the D+ and D−

lines are not shorted, attempting to identify the power source as a known power adapter based at least in part on a value determined for one of the D+ and D−

lines in response to the pull-up or pull-down applied on the other of the D+ and D−

lines.

17. The method as recited in claim 16, further comprising:

positively identifying the known power adapter based at least in part on applying a plurality of pull-ups or pull-downs of different values to at least one of the D+ and D−

lines; and

comparing values of the D+ and D−

lines with previously determined values for particular known power adapters.

18. The method as recited in claim 17, wherein the comparing further comprises comparing values of the D+ and D−

lines with values for a plurality of known power adapters previously determined and stored in a power adapter information table.

19. The method as recited in claim 16, further comprising, when the attempting to identify the power source as a known power adapter is unsuccessful, setting a level of current to be drawn from the power source to a default level of current.

20. One or more non-transitory computer-readable media having instructions recorded thereon, the instructions executable by a processor to program a device to perform operations comprising:

detecting that a power source is connected to a universal serial bus (USB) port of the device, the USB port including a D+ line and a D−

line;

based at least in part on determining that the power source is not a host USB port of another device, setting a USB device controller of the device to operate in a host controller mode;

in the host controller mode, applying a pull-up or pull-down on one of the D+ or D−

lines of the USB port; and

determining from a comparison of values of the D+ and D−

lines whether the D+ and D−

lines are floating.

21. The one or more non-transitory computer-readable media as recited in claim 20, wherein applying the pull-up or pull-down further comprises connecting a resistor of a known resistance between the one of the D+ or D−

lines and a voltage source or voltage drain, respectively.

22. The one or more non-transitory computer-readable media as recited in claim 20, the operations further comprising, when the D+ and D−

lines are not determined to be floating, setting a level of current to be drawn from the power source to a predefined current level for power adapters having shorted D+ and D−

lines.

23. The one or more non-transitory computer-readable media as recited in claim 20, the operations further comprising, when the D+ and D−

lines are determined to be floating, determining whether the power source is a known power adapter based, at least in part, on comparing the values of the D+ and D−

lines with one or more stored values of D+ and D−

lines for one or more known power adapters.

24. The one or more non-transitory computer-readable media as recited in claim 23, the operations further comprising, when the power source is not identified as a known power adapter, setting a default current level to be drawn from the power source.

25. The one or more non-transitory computer-readable media as recited in claim 20, the operations further comprising, following a determination of a current level to be drawn from the power source, resetting the USB device controller to operate in a device controller mode.