Electronic device and method of identifying frequency for detecting touches

1. A method comprising:

identifying a first plurality of drive frequencies at which drive electrodes of a touch-sensitive display of an electronic device are driven, wherein the first plurality of drive frequencies includes a first frequency and a second frequency;

determining a first noise value at the first frequency;

in response to determining that the first noise value meets a first threshold value, comparing the first noise value to a second threshold that is greater than the first threshold value; and

in response to determining that the first noise value is less than the second threshold value that is greater than the first threshold value:

determining, by the electronic device, a second noise value at the second frequency and

driving the drive electrodes at the second frequency in response to determining that the second noise value is less than the first threshold value;

in response to determining that the first noise value meets the second threshold value, identifying, by the electronic device, a third frequency at which the drive electrodes are driven, wherein the third frequency is not one of the first plurality of drive frequencies by:

receiving, from sense electrodes of the touch-sensitive display, a sense signal at the third frequency while the drive electrodes are not driven;

determining a third noise value for the third frequency; and

determining whether the third noise value is less than an identification threshold.

2. The method according to claim 1 , comprising adding the third frequency to the first plurality of frequencies.

3. The method according to claim 1 , comprising adding the third frequency to a second plurality of frequencies, wherein the second plurality of frequencies does not include the first frequency and the second frequency.

4. The method according to claim 1 , comprising, when the first noise value meets the second threshold value, identifying a fourth frequency at which the drive electrodes are driven, wherein the fourth frequency is not one of the plurality of frequencies.

5. The method according to claim 1 , comprising, when the second noise value meets the first threshold value and is less than the second threshold value:

determining a noise value at a fourth frequency of the first plurality of drive frequencies and

utilizing the fourth frequency to drive the drive electrodes in response to determining that the noise value at the fourth frequency is less than the first threshold value.

6. The method according to claim 1 , wherein identifying the first plurality of signal frequencies comprises:

selecting the first frequency;

receiving, from sense electrodes of the touch-sensitive display, a first sense signal at the first frequency while the drive electrodes are not driven;

determining the first noise value for the first sense signal;

determining that the first noise value is less than an identification threshold; and

adding the first frequency to the first plurality of frequencies.

7. The method according to claim 1 , comprising, when the first noise value is less than the first threshold value, driving the drive electrodes at the first frequency.

8. The method according to claim 1 , wherein determining the first noise value comprises determining the first noise value while the drive electrodes are not driven.

9. The method according to claim 1 , wherein determining the first noise value at the first frequency is performed in response to determining that the electronic device is coupled to an external power source.

10. A non-transitory computer-readable storage device having computer-readable code executable by at least one processor of the portable electronic device to perform the method of claim 1 .

11. An electronic device comprising:

a touch-sensitive input device comprising a plurality of drive electrodes and a plurality of sense electrodes;

a controller coupled to the plurality of drive electrodes and the plurality of sense electrodes and configured to:

identify a first plurality of frequencies at which the drive electrodes are driven, wherein the first plurality of frequencies include a first frequency and a second frequency;

determine a first noise value at the first frequency;

in response to determining that the first noise value meets a first threshold value, comparing the first noise value to a second threshold that is greater than the first threshold value; and

in response to determining that the first noise value is less than second threshold value that is greater than the first threshold value:

determine a second noise value at the second drive frequency and

drive the drive the drive electrodes at the second frequency in response to determining that the second noise value is less than the first threshold value;

in response to determining that the first noise value meets the second threshold value, identify a third frequency at which the drive electrodes are driven, wherein the third frequency is not one of the plurality of frequencies, by:

receiving, from sense electrodes of the touch-sensitive display, a sense signal at the third frequency while the drive electrodes are not driven;

determining a third noise value for the third frequency; and

determining whether the third noise value is less than an identification threshold.

12. The electronic device according to claim 11 , wherein the third frequency is added to the first plurality of frequencies.

13. The electronic device according to claim 11 , wherein the third frequency is added to a second plurality of frequencies, wherein the second plurality of frequencies does not include the first frequency and the second frequency.

14. The electronic device according to claim 11 , wherein, when the first noise value meets the second threshold value, a fourth frequency at which the drive electrodes are driven is identified, wherein the fourth frequency is not one of the plurality of frequencies.

15. The electronic device according to claim 11 , wherein, when the second noise value meets the first threshold value and is less than the second threshold value, a noise value at an other frequency of the first plurality of drive frequencies is identified and is utilized to drive the drive electrodes.

16. The electronic device according to claim 11 , wherein determining the first noise value comprises determining the first noise value while the drive electrodes are not driven.

17. The electronic device according to claim 11 , comprising a processor configured to send a notification to a controller of the touch-sensitive display when the electronic device is coupled to an external power source, and wherein the controller is configured to detect the first noise value in response to receipt of the notification.