POWERED COMMUNICATIONS INTERFACE WITH PRE-OPERATING MODE USING LOW VOLTAGES AND CURRENTS FOR INFORMATION SIGNALING

• US 20100095136A1
• Filed: 10/10/2008
• Published: 04/15/2010
• Est. Priority Date: 10/10/2008
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Karam, Roger
• Granted Patent: US 8,099,611 B2
• Time in Patent Office: Days
• US Class Current: 713/300
• 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: H04L 12/10 Current supply arrangements

Abstract

A powered device can provide information to another device (such as a power sourcing equipment) via a powered communications interface when operating power is not being provided to the powered device via the powered communications interface, enabling a variety of functions and applications. Relatively low voltages and currents of the type used for detection and classification of the powered device are used in an extended way to achieve the communications. The power sourcing equipment performs additional detections and/or classifications, and the powered device responds by presenting corresponding signatures or identity networks that convey additional information beyond the presence and power requirements of the powered device. As an example, a powered device can present a sequence of signatures signifying that power should be applied to the powered device notwithstanding an active policy of withholding power in furtherance of a power conservation scheme. Many other kinds of information can be signaled for a variety of system-level purposes and using a variety of signal forms using the relatively low signaling voltages and currents.

Claims

1. A method of operating a powered communications interface of a power-sourcing equipment, the powered communications interface including coupling circuitry operative to couple data signals between the power-sourcing equipment and conductors of the cable, the method comprising:

in a powered operating mode, supplying operating power to the powered device via the coupling circuitry in the form of a relatively high supply voltage across the conductors of the cable and a relatively high supply current through the conductors of the cable; and

in a non-powered operating mode, (1) withholding the operating power from the powered device, and (2) applying a sequence of relatively low signaling voltages and relatively low signaling currents to the conductors of the cable via the coupling circuitry, the sequence of relatively low signaling voltages and currents including (a) first signaling voltages and currents of a detection and classification operation by which the presence and power requirements of the powered device are detected, and (b) second signaling voltages and currents by which the powered device provides additional information to the power-sourcing equipment, the additional information being encoded in the form of values and sequence of the second signaling currents conducted by the powered device in response to corresponding values and sequence of the second signaling voltages.

2. A method according to claim 1, wherein at least initial ones of the second signaling voltages are compliant with published standards specifying the magnitude and timing of the signaling voltages.

3. A method according to claim 2, wherein subsequent ones of the second signaling voltages are not compliant with the published standards and constitute manufacturer-specific exchange of information between the power-sourcing equipment and the powered device.

4. A method according to claim 1, wherein:

the power-sourcing equipment is provided with a control value indicating that the power-sourcing equipment is normally to withhold power even when the detection/classification operation indicates that the powered device is present;

the additional information indicates the existence of a special operating condition of the powered device which should override the normal withholding of power; and

the powered operating mode is entered in response to receiving the additional information from the powered device.

5. A method according to claim 1, wherein the second signaling voltages and currents are of additional detection/classification operations operative to detect multiple identification networks of the powered device.

7. A method according to claim 1, wherein the powered device is a power-only device lacking circuitry for performing high-speed communications via the communications channels.

8. A method according to claim 1, further comprising:

during the powered operating mode, (1) monitoring for the occurrence of a fault condition, and (2) in response to detection of the fault condition, ceasing to supply power to the powered device via the coupling circuitry and setting a debug flag indicating that the fault condition was detected; and

during a subsequent execution of the pre-operating mode, (1) prior to applying the second signaling voltages and currents, checking whether the debug flag is set, and (2) only if the debug flag is set, then applying the second signaling voltages and currents and interpreting the additional information from the powered device as information pertaining to the fault condition.

10. A method according to claim 1, wherein the detection and classification operation is active at the same time as the providing of additional information to the power-sourcing equipment.

11. A method according to claim 1, wherein the detection and classification operation and the providing of additional information to the power-sourcing equipment are active at different times.

12. A method according to claim 11, wherein the completion of one of the two activities of (1) the detection and classification operation, and (2) the providing of additional information to the power-sourcing equipment, leads to the initiation of the other of the two activities or the initiation of additional activities.

16. A power-sourcing equipment according to claim 12, wherein:

the power-sourcing equipment is provided with a control value indicating that the power-sourcing equipment is normally to withhold power even when the detection/classification operation indicates that the powered device is present;

the additional information indicates the existence of a special operating condition of the powered device which should override the normal withholding of power; and

the powered operating mode is entered in response to receiving the additional information from the powered device.

6. A method according to claim 6, wherein the additional detection/classification operations are performed in parallel.

9. A method according to claim 9, further comprising performing time-domain reflectometry to obtain TDR result information about the fault condition.

13. A power-sourcing equipment to be coupled to a powered device via a cable, comprising:

coupling circuitry operative to couple data signals between the power-sourcing equipment and conductors of the cable;

power circuitry connected to the coupling circuitry, the power circuitry being operative under control of power control signals to provide operating power to the powered device via the conductors of the cable; and

power control circuitry operative, when the power-sourcing equipment is coupled to the powered device via the cable, to generate the power control signals;

(i) in a powered operating mode, to control the power circuitry to supply the operating power to the powered device in the form of a relatively high supply voltage across the conductors of the cable and a relatively high supply current through the conductors of the cable; and

(ii) in a non-powered operating mode, to (1) control the power circuitry to withhold the operating power from the powered device, and (2) apply a sequence of relatively low signaling voltages and relatively low signaling currents to the conductors of the cable, including (a) first signaling voltages and currents of a detection and classification operation by which the presence and power requirements of the powered device are detected, and (b) second signaling voltages and currents by which the powered device provides additional information to the power-sourcing equipment, the additional information being encoded in the form of values and sequence of the second signaling currents conducted by the powered device in response to corresponding values and sequence of the second signaling voltages.

14. A power-sourcing equipment according to claim 13, wherein at least initial ones of the second signaling voltages are compliant with published standards specifying the magnitude and timing of the signaling voltages.

15. A power-sourcing equipment according to claim 14, wherein subsequent ones of the second signaling voltages are not compliant with the published standards and constitute manufacturer-specific exchange of information between the power-sourcing equipment and the powered device.

17. A power-sourcing equipment according to claim 13, wherein the second signaling voltages and currents are of additional detection/classification operations operative to detect multiple identification networks of the powered device.

18. A power-sourcing equipment according to claim 17, wherein the additional detection/classification operations are performed in parallel.

19. A power-sourcing equipment according to claim 13, wherein the power circuitry and power control circuitry are further operative to:

during the powered operating mode, (1) monitor for the occurrence of a fault condition, and (2) in response to detection of the fault condition, cease to supply power to the powered device via the coupling circuitry and set a debug flag indicating that the fault condition was detected; and

during a subsequent execution of the pre-operating mode, (1) prior to applying the second signaling voltages and currents, check whether the debug flag is set, and (2) only if the debug flag is set, then apply the second signaling voltages and currents and interpreting the additional information from the powered device as information pertaining to the fault condition.

20. A power-sourcing equipment according to claim 19, further operative to perform time-domain reflectometry to obtain TDR result information about the fault condition.

21. A powered device for coupling to a power-sourcing equipment, comprising:

coupling circuitry to be coupled to the power-sourcing equipment via a cable, the coupling circuitry being capable of transferring high-speed data communications signals between the powered device and conductors of the cable; and

power circuitry and power control circuitry configured and operative to;

(A) in a powered operating mode, receive operating power from the power-sourcing equipment via the coupling circuitry in the form of a relatively high supply voltage across the conductors of the cable and a relatively high supply current through the conductors of the cable; and

(B) in a non-powered operating mode, (1) not receive the operating power from the power-sourcing equipment via the coupling circuitry, and (2) receive a sequence of relatively low signaling voltages and relatively low signaling currents from the power-sourcing equipment via the conductors of the cable and the coupling circuitry, the sequence of relatively low signaling voltages and currents including (a) first signaling voltages and currents of a detection and classification operation by which the presence and power requirements of the powered device are detected, and (b) second signaling voltages and currents by which the powered device provides additional information to the power-sourcing equipment, the additional information being encoded in the form of values and sequence of the second signaling currents conducted by the powered device in response to corresponding values and sequence of the second signaling voltages.

22. A powered device according to claim 21, wherein the additional information indicates the existence of a special operating condition of the powered device which should override a withholding of power occurring at the power-sourcing equipment.

23. A powered device according to claim 21, being a power-only device lacking circuitry for performing high-speed communications via the coupling circuitry.