System and Method for Enumerating a USB Device Using Low Power

• US 20080126594A1
• Filed: 08/17/2006
• Published: 05/29/2008
• Est. Priority Date: 08/17/2006
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Standard Microsystems Corporation (Microchip Technology Incorporated)
• Inventors: Monks, Morgan H., Bohm, Mark R.
• Granted Patent: US 7,624,202 B2
• Time in Patent Office: Days
• US Class Current: 710/17
• 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

System and method for enumerating and/or enumerating a device. The device may be a USB portable device which adheres to a first standard, e.g., the USB specification, and may engage in enumeration with respect to a USB hub/USB host device. Where a battery included in the device is sufficiently low, the device may engage in low power enumeration, e.g., to begin charging the device using enumerated power. Low power enumeration may allow the device to enumerate even when the device is incapable of powering on. Additionally, or alternatively, the device may determine whether the hub/host device is capable of providing high power charging. If it is, the device may begin charging the battery of the device using power provided by the hub/host device at a high power level.

Claims

1. A USB device, comprising:

a battery;

at least one port, coupled to the battery, wherein the at least one port is operable to couple to a host USB device which is operable to charge the battery, where the at least one port is operable to receive an enumeration request from the host USB device; and

detection logic coupled to the battery and operable to detect a charge state of the battery, wherein the detection logic is operable to enable the USB device to engage in USB device enumeration in response to the enumeration request if the charge state of the battery is sufficient to engage in the USB device enumeration; and

first circuitry coupled to the detection logic, wherein the first circuitry is operable to engage in low-power enumeration of the USB device if the charge state of the battery is not sufficient to engage in USB device enumeration, wherein the first circuitry is operable to use power received from the host USB device in performing the low-power enumeration.

2. The USB device of claim 1, further comprising:

battery charging circuitry, coupled to the battery and the at least one port, wherein the battery charging circuitry is operable to charge the battery using power received from the host USB device.

3. The USB device of claim 2, wherein the USB device further comprises device circuitry, wherein the device circuitry is operable to perform functions of the USB device and engage in the USB device enumeration of the USB device;

and

wherein the detection logic is operable to determine if the charge state of the battery is sufficient during charging, and wherein, if the detection logic determines that the charge state of the battery is sufficient, the device circuitry is further operable to engage in the USB device enumeration.

4. The USB device of claim 1, wherein the USB device further comprises device circuitry, wherein the device circuitry is operable to perform functions of the USB device and engage in the USB device enumeration of the USB device if the battery is sufficiently charged.

5. The USB device of claim 1, wherein the USB device conforms to a first standard, and wherein the first standard specifies provision of maximum power to the USB device at a first power level, and wherein the detection logic is further operable to:

determine if the USB device should receive high-power charging of the battery; and

request and receive high-power to charge the battery from the host USB device if the USB device should receive high-power charging, wherein power received from the host USB device during high-power charging is at a second power level, wherein the second power level is greater than the first power level, and wherein, prior to and during high-power charging, the USB device is not enumerated.

6. The USB device of claim 1, wherein the USB device further comprises device circuitry, wherein the device circuitry is operable to perform functions of the device if the battery is sufficiently charged, and wherein a user of the USB device is operable to use the USB device via the functions of the USB device while the USB device is being charged.

7. The USB device of claim 1, wherein the power received from the host USB device in performing the low-power enumeration comprises a current which is substantially 100 milliamps (mA) or less.

8. The USB device of claim 1, wherein power received from the host USB device after enumeration comprises a current which is substantially 500 mA or less.

9. The USB device of claim 1, wherein the low power enumeration comprises low power or full speed enumeration.

10. A method for charging a USB device, comprising:

detecting coupling of the USB device to a USB host device;

determining if a battery of the USB device is sufficiently charged for USB device enumeration;

if the battery of the USB device is not sufficiently charged for USB device enumeration, engaging in enumeration of the USB device using low-power enumeration, wherein said engaging in enumeration of the USB device using low-power enumeration comprises engaging in enumeration of the USB device using power received from the USB host device during enumeration.

11. The method of claim 10, further comprising:

charging the battery of the USB device.

12. The method of claim 10, further comprising:

if the battery of the USB is sufficiently charged for normal enumeration, engaging in USB device enumeration of the USB device.

13. The method of claim 10, further comprising:

determining the charge state of the battery during said charging the battery if the battery of the USB device was enumerated using low-power enumeration;

if the charge state of the battery is sufficient based on said determining, powering the USB device.

14. The method of claim 13, wherein said powering the USB device is performed in response to user input or automatically, wherein said automatically powering the USB device is performed without user input specifying powering of the USB device.

15. The method of claim 13, further comprising:

if the charge state of the battery is sufficient based on said determining, engaging in USB device enumeration of the USB device.

16. The method of claim 10, wherein the USB device conforms to a first standard, wherein the first standard specifies provision of maximum power to the device at a first power level, and wherein the method further comprises:

determining if the USB device requires high-power charging of the battery; and

requesting and receiving power at a second power level to charge the battery from the host USB device if the USB device requires high-power charging, wherein the second power level is greater than the first power level.

17. The method of claim 16, further comprising:

charging the battery with the power received from the host USB at the second power level.

18. The method of claim 10, wherein the power received from the host USB device during enumeration comprises a current which is substantially 100 milliamps (mA).

19. The method of claim 10, further comprising:

charging the battery with enumerated power received from the USB host if the USB device is enumerated.

20. The method of claim 19, wherein the received enumerated power comprises a current which is substantially 500 mA.

21. A method for charging a USB device, comprising:

detecting coupling of the USB device to a USB host device, wherein the USB device comprises a battery;

if the battery of the USB device is not sufficiently charged for USB device enumeration, engaging in enumeration of the USB device using low-power enumeration, wherein said engaging in enumeration of the USB device using low-power enumeration comprises engaging in enumeration of the USB device using power received from the USB host device during enumeration.