Cable presence detection for detecting a connection between two devices

• US 7,423,434 B2
• Filed: 01/06/2005
• Issued: 09/09/2008
• Est. Priority Date: 01/06/2005
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Stancil, Charles J.
• Primary Examiner(s): Nguyen; Vincent Q.
• Assistant Examiner(s): NATALINI, JEFF WILLIAM
• Application Number:
  US11/030,028
• Publication Number:
  US 20060146485A1
• Time in Patent Office: 1,342 Days
• Field of Search: 324/66
• US Class Current: 324/539
• CPC Class Codes: G01R 31/69 of terminals at the end of a cable or a wire harness; of plugs; of sockets, e.g. wall sockets or power sockets in appliances

Abstract

Systems, methodologies, media, and other embodiments associated with detecting devices connected to a cable are described. One exemplary system embodiment includes logic configured to determine whether devices are connected to a cable and are powered while maintaining ground isolation between the devices.

Claims

1. A system for detecting a cable connection between a first device and a second device, the system comprising:

a bi-directional detection logic configured within the first device to generate a first signal that indicates whether a power signal from the second device is present from the cable where the first signal and the power signal are electrically isolated from each other; and

the bi-directional detection logic being further configured to generate a second signal that indicates whether the first device is connected and powered where the second signal is configured to be transmitted over the cable to the second device while maintaining ground isolation between the first device and the second device;

where the bidirectional detection logic includes;

a first optical isolator including a diode configured to be powered by the power signal of the second device, and including a phototransistor configured to generate the first signal while electrically isolating the first signal from the power signal of the second device;

and a second optical isolator including a diode configured to be powered by the first device, and including a phototransistor configured to conduct the power signal back to the second device through the cable if the diode is powered.

2. The system of claim 1 where the second signal is formed from the power signal of the second device.

3. The system of claim 1 where the first signal is configured to be used by the first device to determine whether the second device is connected to the cable and is powered, and where the second signal is configured to be used by the second device to determine whether the first device is connected to the cable and is powered.

4. The system of claim 1 where bi-directional logic is configured to communicate with the cable being one of:

a PCI Express cable, a serial cable, a Universal Serial Bus cable, and an Ethernet cable.

5. The system of claim 1 where the bi-directional logic includes:

means for generating the first signal that indicates whether the power signal from the second device is present from the cable; and

means for generating the second signal that indicates whether the first device is connected and powered, while maintaining ground isolation between the first device and the second device.

6. The system of claim 1, where the cable includes:

a first signal line configured to conduct the power signal from the second device to the first device; and

a second signal line configured to conduct the second signal from the first device to the second device.

7. A method of manufacturing an electrical device for indicating connectivity over a cable between the electrical device and a remote device, the method comprising:

configuring a first isolator, in the electrical device, to indicate to the remote device whether the electrical device is connected to the cable and is powered while maintaining ground isolation between the electrical device and the remove device; and

configuring a second isolator, in the electrical device, to detect whether the remote device is connected to the cable and is powered where the electrical device and remote device are ground isolated;

where the first isolator includes an optical isolator having a first phototransistor and a first diode, the method further including;

operatively connecting the first phototransistor to receive a power signal from the remote device over a first cable line, where the power signal is conducted back to the remote device over a second cable line based on a state of the first diode;

and operatively connecting the first diode to be powered by the electrical device.

8. The method of claim 7 where the second isolator includes an optical isolator having a second diode and a second phototransistor, the method further including:

operatively connecting the second diode to be powered by the remote device where the second diode controls a state of the second phototransistor; and

operatively connecting the second phototransistor to generate a status signal based on the state of the phototransistor, the status signal used to indicate whether the remote device is connected to the cable and is powered.

9. A electrical device configured to detect whether a remote device is connected thereto by a cable, the electrical device comprising:

a first optical isolator including;

a first diode configured to be powered by the electrical device; and

a first phototransistor being operatively connected to receive power from the remote device over a first signal line of the cable, and when the first diode is powered, the first phototransistor is configured to conduct the power onto a second signal line of the cable as a first output signal back to the remote device, and when the first diode is not powered, the first phototransistor is configured to not conduct the power to the second signal line where the first output signal on the second signal line is used by the remote device to determine whether the electrical device is connected to the cable and is powered;

a second optical isolator including;

a second diode configured to be powered by the remote device; and

a second phototransistor having an emitter being operatively connected to a ground of the electrical device and having a collector operatively connected to a power source of the electrical device to produce a second output signal, where the second phototransistor is in an off state when the second diode is not powered and is in an on state when the second diode is powered;

a logic configured to sense the second output signal to determine whether the remote device is connected to the cable and is powered; and

where the electrical device and the remote device are ground isolated.

10. The electrical device of claim 9 where the second diode is configured to receive power from the remote device from an emitter of the first phototransistor.

11. The electrical device of claim 9 where the first output signal and the second output signal provide for bi-directional presence detection of the electrical device and the remote device.

12. The electrical device of claim 9 where the cable includes a cable compatible with PCI Express.

13. A method comprising:

transmitting a power signal over a first cable line from a first device to a second device;

returning the power signal over a second cable line from the second device to the first device if the second device is powered while maintaining ground isolation between the first device and the second device;

determining, by the first device, whether the second device is powered by sensing the power signal from the second cable line;

powering a diode, in the second device, with the power signal from the first device where the diode includes a state including an on state when the power signal is present and an off state when the power signal is not present; and

determining, by the second device, whether the first device is powered by sensing the state of the diode while maintaining ground isolation between the first device and the second device.

14. A system, comprising:

means for determining, in a first device, whether a second device is connected to a cable means with the first device and is powered while maintaining ground isolation between the first device and the second device; and

means for indicating to the second device whether the first device is connected to the cable means and is powered while maintaining ground isolation between the first device and the second device;

where the means for indicating include a first optical isolator including a first diode configured to be powered by the first device and a first phototransistor operatively connected to receive power from the second device over a first signal line of the cable, and when the first diode is powered, the first phototransistor is configured to conduct the power onto a second signal line of the cable as a first output signal back to the second device, and when the first diode is not powered, the first phototransistor is configured to not conduct the power to the second signal line where the first output signal on the second signal line is used by the second device to determine whether the first device is connected to the cable and is powered.

15. The system of claim 14 where the cable means includes a PCI Express cable.

16. The system of claim 14 where the means for determining includes an optical isolator.

17. The system of claim 14 where the means for determining and the means for indicating include circuitry configured with one or more of:

relays, electrical isolation circuits, optical isolators, and combinations thereof.