Smart scanning for a capacitive sensing array

1. A method comprising:

simultaneously driving a plurality of transmit electrodes in each of a plurality of scan groups in a capacitive sense array to generate a group receive signal for each of the plurality of scan groups corresponding to a mutual capacitance at sense elements of the capacitive sense array that form the scan group, wherein each of the plurality of scan groups comprises a plurality of sense elements;

determining, based on the group receive signals from the plurality of scan groups, a scan group where the generated receive signal is affected by a presence of a conductive object in proximity to the capacitive sense array, wherein each of a number of receive electrodes that form one of the plurality of scan groups share a single receive processing channel of a plurality of receive processing channels;

sequentially driving one or more of the plurality of transmit electrodes in an identified scan group with a transmit signal, where the generated receive signal corresponding to the identified scan group is affected by the presence of the conductive object in proximity to the capacitive sense array; and

determining, based on individual receive signals on each of the receive electrodes that form the identified scan group resulting from the sequential driving, a location of the conductive object, wherein each of the receive electrodes that form the identified scan group are coupled to a separate receive processing channel of the plurality of receive processing channels.

2. The method of claim 1 , wherein the number of receive electrodes that form each of the plurality of scan groups is based on a total number of receive electrodes and a number of receive channels in a capacitive sensing device.

3. The method of claim 1 , further comprising:

measuring a baseline capacitance value for each of the plurality of scan groups in the capacitive sense array; and

measuring a baseline capacitance value for each of the sense elements in the capacitive sense array.

4. The method of claim 3 , wherein identifying a scan group comprises:

comparing a value corresponding to the mutual capacitance for the scan group to the baseline capacitance value for the scan group to determine a differential value; and

determining if the differential value is greater than a touch threshold value.

5. The method of claim 1 , wherein a first scan group of the plurality of scan groups overlaps a second adjacent scan group by at least one electrode.

6. An apparatus comprising:

a capacitive sense array having a plurality of sense elements; and

a processing device coupled to the capacitive sense array, the processing device to:

simultaneously drive a plurality of transmit electrodes in each of a plurality of scan groups in the capacitive sense array to generate a group receive signal for each of the plurality of scan groups corresponding to a mutual capacitance at the sense elements that form the scan group, wherein each of the plurality of scan groups comprises a subset of the plurality of sense elements;

determine, based on the group receive signals from the plurality of scan groups, a scan group where the generated receive signal is affected by a presence of a conductive object in proximity to the capacitive sense array, wherein each of a number of receive electrodes that form one of the plurality of scan groups share a single receive processing channel of a plurality of receive processing channels;

sequentially drive one or more of the plurality of transmit electrodes in an identified scan group with a transmit signal, where the generated receive signal corresponding to the identified scan group is affected by the presence of the conductive object in proximity to the capacitive sense array; and

determine, based on individual receive signals on each of the receive electrodes that form the identified scan group resulting from the sequential driving, a location of the conductive object, wherein each of the receive electrodes that form the identified scan group are coupled to a separate receive processing channel of the plurality of receive processing channels.

7. The apparatus of claim 6 , wherein the number of receive electrodes that form each of the plurality of scan groups is based on a total number of receive electrodes and a number of receive channels in a capacitive sensing device.

8. The apparatus of claim 6 , wherein the processing device is further to:

measure a baseline capacitance value for each of the plurality of scan groups in the capacitive sense array; and

measure a baseline capacitance value for each of the sense elements in the capacitive sense array.

9. The apparatus of claim 8 , wherein in order to determine if a conductive object is present, the processing device to:

compare a value corresponding to the mutual capacitance for a scan group to the baseline capacitance value for the scan group to determine a differential value; and

determine if the differential value is greater than a touch threshold value.

10. The apparatus of claim 6 , wherein a first scan group of the plurality of scan groups overlaps a second adjacent scan group by at least one electrode.

11. An apparatus comprising:

a touch-sensor device, the touch-sensor device comprising an array of capacitive sense elements, the array comprising a plurality of transmit electrodes and a plurality of receive electrodes;

a transmit selection circuit coupled to the touch-sensor device, the transmit selection circuit to selectively apply a transmit signal to one or more of the transmit electrodes;

a receive selection circuit coupled to the touch-sensor device, the receive selection circuit to selectively measure a signal from one or more of the receive electrodes, wherein the measured signal corresponds to a mutual capacitance value between a transmit electrode and a receive electrode; and

a processing device coupled to the touch-sensor device, the processing device to:

simultaneously drive a plurality of transmit electrodes in a scan group of the capacitive sense array, wherein the scan group comprises the plurality of transmit electrodes and a plurality of receive electrodes;

determine, based on a group receive signal from the scan group, if a conductive object is present on the touch-sensor device in an area corresponding to the scan group, wherein each of the plurality of receive electrodes that form the scan group share a single receive processing channel of a plurality of receive processing channels;

if a conductive object is present on the touch-sensor device in the area corresponding to the scan group, sequentially drive one or more of the plurality of transmit electrodes in the scan group with a transmit signal; and

determine, based on individual receive signals on each of the receive electrodes that form the scan group resulting from the sequential driving, a location of the conductive object, wherein each of the receive electrodes that form the identified scan group are coupled to a separate receive processing channel of the plurality of receive processing channels.

12. The apparatus of claim 11 , wherein the number of receive electrodes that form each of the plurality of scan groups is based on a total number of receive electrodes and a number of receive channels in a capacitive sensing device.

13. The apparatus of claim 11 , wherein when the processing device determines the location of the conductive object, the processing device to:

determine a coordinate value corresponding to the location of the conductive object; and

provide the coordinate value to a host machine.

14. The apparatus of claim 11 , wherein the capacitive sense array comprises a plurality of scan groups and wherein a first scan group of the plurality of scan groups overlaps a second adjacent scan group by at least one sense element.