Interleaved scanning for capacitive touch sensors
A touch sensing circuit includes: a plurality of sensor channels; a controller coupled to the plurality of sensor channels, the controller configured to: map the sensor channels to sensor nodes, the sensor nodes forming a plurality of interleaved lumped sensors, where at least two of the interleaved lumped sensors include a common sensor node; scan, during a scan period, the interleaved lumped sensors to detect one or more touch inputs; and responsive to detecting one or more touch inputs, determining a location of at least one touch input.
1. A touch sensing circuit comprising:
a plurality of sensor channels;
a controller coupled to the plurality of sensor channels, the controller configured to:
map the sensor channels to sensor nodes, the sensor nodes forming a plurality of interleaved lumped sensors, where at least two of the interleaved lumped sensors include a common sensor node;
scan, during a scan period, the interleaved lumped sensors to detect one or more touch inputs; and responsive to detecting one or more touch inputs,
determining a location of at least one touch input.
2. The touch sensing circuit of claim 1 , wherein the controller is further configured to:
scan a sensor node in an interleaved lumped sensor to resolve a detection ambiguity between two or more interleaved lumped sensors that are touched.
3. The touch sensing circuit of claim 1 , wherein the controller is further configured to:
compare changes in capacitance measured on two or more interleaved lumped sensors to resolve a detection ambiguity between the two or more interleaved lumped sensors.
4. The touch sensing circuit of claim 1 , wherein the controller is further configured to map the interleaved lumped sensors to rows and columns of a two-dimensional (2D) surface to thereby form a one-dimensional (1D) lumped sensor.
5. The touch sensing circuit of claim 4 , wherein the 1D lumped sensor is a slider.
6. The touch sensing circuit of claim 4 , wherein the controller is further configured to determine a location of a single touch input on the 2D surface based on which 1D lumped sensors are touched.
7. The touch sensing circuit of claim 4 , wherein the controller is further configured to scan individual sensor nodes in the 1D lumped sensors to resolve a location ambiguity on the 2D surface.
8. A method of touch sensing comprising:
mapping, by a controller of a touch sense circuit, sensor channels to sensor nodes, the sensor nodes forming a plurality of interleaved lumped sensors, where at least two of the interleaved lumped sensors include a common sensor node;
scanning, during a scan period, the interleaved lumped sensors to detect one or more touch inputs; and responsive to detecting one or more touch inputs,
determining a location of at least one touch input.
9. The method of claim 8 , further comprising:
scanning, by the controller, a sensor node in an interleaved lumped sensor to resolve a detection ambiguity between two or more interleaved lumped sensors that are touched.
10. The method of claim 8 , further comprising:
comparing, by the controller, changes in capacitance measured on two or more interleaved lumped sensors to resolve a detection ambiguity between the two or more interleaved lumped sensors.
11. The method of claim 8 , wherein the controller is further configured to map the interleaved lumped sensors to rows and columns of a two-dimensional (2D) surface to thereby form a one-dimensional (1D) lumped sensor.
12. The method of claim 11 , wherein the 1D lumped sensor is a slider.
13. The method of claim 11 , further comprising:
determining, by the controller, a location of a single touch input on the 2D surface based on which 1D lumped sensors are touched.
14. The method of claim 11 , further comprising:
scanning, by the controller, individual sensor nodes in the 1D lumped sensors to resolve a location ambiguity on the 2D surface.
15. A touch sensing system comprising:
sensor nodes;
a microcontroller;
a controller coupled to the microcontroller and the sensor nodes, the controller configured to:
map the sensor channels to the sensor nodes, the sensor nodes forming a plurality of interleaved lumped sensors, where at least two of the interleaved lumped sensors include a common sensor node;
scan, during a scan period, the interleaved lumped sensors to detect one or more touch inputs; responsive to detecting one or more touch inputs,
determining a location of at least one touch input; and
reporting the location to the microcontroller.
16. The touch sensing system of claim 15 , wherein the controller is configured to:
scan a sensor node in an interleaved lumped sensor to resolve a detection ambiguity between two or more interleaved lumped sensors that are touched.
17. The touch sensing system of claim 15 , wherein the controller is configured to:
compare changes in capacitance measured on two or more interleaved lumped sensors to resolve a detection ambiguity between the two or more interleaved lumped sensors.
18. The touch sensing system of claim 15 , wherein the controller is further configured to map the interleaved lumped sensors to rows and columns of a two-dimensional (2D) surface to thereby form a one-dimensional (1D) lumped sensor.
19. The touch sensing system of claim 18 , wherein the controller is configured to determine a location of a single touch input on the 2D surface based on which 1D lumped sensors are touched.
20. The touch sensing system of claim 18 , wherein the controller is configured to scan individual sensor nodes in the 1D lumped sensors to resolve a location ambiguity on the 2D surface.