Detecting a connection to an unpowered host

• US 8,024,491 B1
• Filed: 08/20/2008
• Issued: 09/20/2011
• Est. Priority Date: 08/20/2007
• Status: Active Grant

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Wright, David, Abbott, Shane, Richardson, Derek
• Primary Examiner(s): Hafiz, Tariq
• Assistant Examiner(s): SUN, SCOTT C
• Application Number:
  US12/195,374
• Time in Patent Office: 1,126 Days
• Field of Search: None
• US Class Current: 710/8
• CPC Class Codes: G06F 13/4295 using an embedded synchronisation

Abstract

A method and apparatus for detecting a connection between a peripheral device and a host device is described.

Claims

1. An apparatus, comprising:

a cable comprising a data line and a cable screen, wherein the cable screen is a conductor configured to shield the data line from interference; and

a sensor coupled with the cable, wherein the sensor is configured to determine whether the cable is connected to a host device by detecting an impedance between the cable screen and a ground of the host device.

2. The apparatus of claim 1, further comprising:

a peripheral device;

the host device; and

the cable, wherein the cable is configured to connect the peripheral device to the host device.

3. The apparatus of claim 1, wherein the sensor is configured to determine whether the cable is connected to a host device when the host device is in one of an unpowered state and a hibernate state.

4. The apparatus of claim 1, wherein the cable is a Universal Serial Bus (USB) cable.

5. The apparatus of claim 1, wherein the peripheral device is a glucose meter.

6. The apparatus of claim 1, wherein the sensor is further configured to detect whether the connection is present in response to a triggering event.

7. The apparatus of claim 1, further comprising a voltage source coupled with the cable screen through a pull-up resistor, wherein the sensor is integrated with a peripheral controller.

8. The apparatus of claim 7, wherein detecting the impedance between the conductor and the ground of the host device comprises detecting a voltage difference between the cable screen and the ground line of the cable, wherein the sensor detects a connection with the host device if a voltage level of the conductor is within a threshold voltage of the ground line.

9. The apparatus of claim 1, further comprising a peripheral controller configured to disable a function of the peripheral device in response to detecting a connection with the host device.

10. A method, comprising:

applying a voltage to a conductor of a cable, wherein the cable is configured to connect a peripheral device to a host device, the conductor comprising a cable screen configured to shield a data line in the cable from interference;

detecting whether a connection is present between the peripheral device and the host device by detecting an impedance between the conductor and a ground of the host device; and

disabling a function of the peripheral device in response to detecting a connection with the host device.

11. The method of claim 10, wherein the host device is in one of an unpowered state and a hibernate state.

12. The method of claim 10, wherein the cable is a Universal Serial Bus (USB) cable.

13. The method of claim 10, wherein the peripheral device is a glucose meter.

14. The method of claim 10, wherein detecting whether the connection is present occurs in response to a triggering event.

15. The method of claim 10, further comprising applying a voltage to the conductor through a pull-up resistor.

16. The method of claim 10, wherein detecting the impedance between the conductor and the ground of the host device comprises detecting a voltage at an input pin of a peripheral controller.

17. The method of claim 10, wherein detecting the impedance between the conductor and the ground of the host device comprises detecting a voltage difference between the conductor and the ground line of the cable, wherein the sensor detects a connection with the host device if a voltage level of the conductor is within a threshold voltage of the ground line.