PRESS ON POWER-UP DETECTION FOR A TOUCH-SENSOR DEVICE

• US 20090114456A1
• Filed: 10/29/2008
• Published: 05/07/2009
• Est. Priority Date: 11/02/2007
• Status: Active Grant

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Wisniewski, John Anthony
• Granted Patent: US 8,395,589 B2
• Time in Patent Office: Days
• US Class Current: 178/18.30
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer

Abstract

A method and apparatus to determine during a power-up of an electronic system whether a conductive object is present at a sensing device at the power-up.

Claims

1. A processing device implemented method comprising:

powering up an electronic system; and

determining during the power-up of the electronic system whether a conductive object is present at a sensing device at the power-up.

2. The method of claim 1, wherein the sensing device comprises a target touch-sensor button and one or more secondary touch-sensor buttons.

3. The method of claim 2, wherein determining whether the conductive object is present comprises:

measuring a baseline capacitance value of the target touch-sensor button;

measuring a baseline capacitance value of the secondary touch-sensor buttons;

determining a difference between the baseline capacitance value of the target touch-sensor button and the baseline capacitance value of the secondary touch-sensor buttons;

comparing the difference to a button threshold value; and

when the difference is greater than the button threshold value, determining that the conductive object is present.

4. The method of claim 3, further comprising:

calculating an offset value for the target touch-sensor button and for each of the secondary touch-sensor buttons, wherein calculating the offset value comprises determining an offset value for the target touch-sensor button and for each of the secondary touch-sensor buttons, such that when the offset value is added to a raw capacitance value, an adjusted capacitance value for the target touch-sensor button and each of the secondary touch-senor buttons is approximately equal.

5. The method of claim 4, wherein measuring the baseline capacitance value of the target touch-sensor button comprises applying the offset value of the target touch-sensor button to a raw capacitance value of the target touch-sensor button.

6. The method of claim 4, wherein measuring the baseline capacitance value of the secondary touch-sensor buttons comprises determining the lowest baseline capacitance value of the secondary touch-sensor buttons.

7. The method of claim 4, wherein measuring the baseline capacitance value of the secondary touch-sensor buttons comprises computing an average baseline capacitance value of the secondary touch-sensor buttons.

8. The method of claim 7, wherein computing the average baseline capacitance value comprises applying an average offset value of the secondary touch-sensor buttons to an average raw capacitance value of the secondary touch-sensor buttons.

9. The method of claim 7, wherein computing the average baseline capacitance value comprises:

applying the offset value for each of the secondary touch-sensor buttons to a raw capacitance value of each of the secondary touch-sensor buttons to generate a baseline capacitance value for each of the secondary touch sensor buttons; and

computing an average of the baseline capacitance values.

10. The method of claim 1, further comprising:

when the conductive object is present at the power-up, updating a status register.

11. The method of claim 1, further comprising:

when the conductive object is present at the power-up, sending an interrupt request to a host processor.

14. The apparatus of claim 10, wherein the signals received from the sensing device represent the capacitance measured on the sensing device.

12. An electronic system comprising:

a processing device configured to receive signals from a sensing device, the processing device to determine at a power-up of the electronic system whether a conductive object is present at the sensing device.

13. The apparatus of claim 12, wherein the processing device comprises one or more capacitance sensors coupled to the sensing device, and wherein the one or more capacitance sensors are configured to measure a capacitance on the sensing device to detect the presence of the conductive object on the sensing device.

15. The apparatus of claim 12, wherein the sensing device comprises a target touch-sensor button and one or more secondary touch-sensor buttons.

16. The apparatus of claim 15, wherein the processing device is configured to:

measure a baseline capacitance value of the target touch-sensor button;

measure a baseline capacitance value of the secondary touch-sensor buttons;

determine a difference between the baseline capacitance value of the target touch-sensor button and the baseline capacitance value of the secondary touch-sensor buttons;

compare the difference to a button threshold value; and

when the difference is greater than the button threshold value, determine that the conductive object is present.

17. The apparatus of claim 12, further comprising:

an interface line coupled between the processing device and a host processor, the interface line to send instructions to update a status register on the host processor when a conductive object is present at the power-up.

18. An electronic system comprising:

means for powering up the electronic system during a first time period; and

means for determining during the first time period whether a conductive object is present at a sensing device.

19. The apparatus of claim 18, wherein the means for detecting comprises a non-mechanical means.

20. The method of claim 18, wherein the means for determining during the first time period occurs before a second time period begins, the second time period comprising detecting when the conductive object is no longer present.