Capacitive sensing
First Claim
1. A device comprising:
- a multi-channel capacitive sensor comprising a drive line; and
a control circuit configured to;
ground a first sense capacitor and a second sense capacitor of the multichannel capacitive sensor, wherein the first sense capacitor and the second sense capacitor are adapted to be connected to the drive line;
charge, by a first voltage provided on a pin of the control circuit, an in-series combination of a sample capacitor and the first sense capacitor using forward conduction of a drive signal by a first diode coupled to the first sense capacitor;
preventing charging of the second sense capacitor, during said charge of the in-series combination of the sample capacitor and the first sense capacitor, by reverse biasing a second diode coupling the second sense capacitor to the pin of the control circuit having the first voltage; and
measure a second voltage on the pin of the control circuit resulting at least in part from charging the in-series combination of the sample capacitor and the first sense capacitor, wherein the second voltage provides an indication of a capacitance of the first sense capacitor.
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Accused Products
Abstract
In one embodiment, a device includes a multi-channel capacitive sensor and a control circuit. The control circuit is configured to ground a first sense capacitor and a second sense capacitor of the multi-channel capacitive sensor. The first sense capacitor and the second sense capacitor are adapted to be connected to a drive line. The control circuit is configured to charge, by a first voltage provided on a pin of the controller, an in-series combination of a sample capacitor and the first sense capacitor while not charging the second sense capacitor by the first voltage provided on the pin of the controller. The control circuit is further configured to measure a second voltage on the pin of the controller resulting at least in part from charging the in-series combination, the second voltage providing an indication of a capacitance of the first sense capacitor.
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Citations
17 Claims
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1. A device comprising:
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a multi-channel capacitive sensor comprising a drive line; and a control circuit configured to; ground a first sense capacitor and a second sense capacitor of the multichannel capacitive sensor, wherein the first sense capacitor and the second sense capacitor are adapted to be connected to the drive line; charge, by a first voltage provided on a pin of the control circuit, an in-series combination of a sample capacitor and the first sense capacitor using forward conduction of a drive signal by a first diode coupled to the first sense capacitor; preventing charging of the second sense capacitor, during said charge of the in-series combination of the sample capacitor and the first sense capacitor, by reverse biasing a second diode coupling the second sense capacitor to the pin of the control circuit having the first voltage; and measure a second voltage on the pin of the control circuit resulting at least in part from charging the in-series combination of the sample capacitor and the first sense capacitor, wherein the second voltage provides an indication of a capacitance of the first sense capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A non-transitory computer-readable medium comprising logic, the logic when executed by one or more processors configured to cause the one or more processors to perform operations comprising:
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grounding a first sense capacitor and a second sense capacitor of a multi-channel capacitive sensor, wherein the first sense capacitor and the second sense capacitor are adapted to be connected to a drive line; charging, by a first voltage provided on a pin of a controller, an in-series combination of a sample capacitor and the first sense capacitor using forward conduction of a drive signal by a first diode coupled to the first sense capacitor; preventing charging of the second sense capacitor, during said charge of the in-series combination of the sample capacitor and the first sense capacitor, by reverse biasing a second diode coupling the second sense capacitor to the pin of the control circuit having the first voltage; and measuring a second voltage on the pin of the controller resulting at least in part from charging the in-series combination of the sample capacitor and the first sense capacitor, wherein the second voltage provides an indication of a capacitance of the first sense capacitor. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method, comprising:
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grounding a first sense capacitor and a second sense capacitor of a multi-channel capacitive sensor, wherein the first sense capacitor and the second sense capacitor are adapted to be connected to a drive line; charging, by a first voltage provided on a pin of a controller, an in-series combination of a sample capacitor and the first sense capacitor using forward conduction of a drive signal by a first diode coupled to the first sense capacitor; preventing charging of the second sense capacitor, during said charge of the in-series combination of the sample capacitor and the first sense capacitor, by reverse biasing a second diode coupling the second sense capacitor to the pin of the control circuit having the first voltage; and measuring a second voltage on the pin of the controller resulting at least in part from charging the in-series combination of the sample capacitor and the first sense capacitor, wherein the second voltage provides an indication of a capacitance of the first sense capacitor. - View Dependent Claims (16, 17)
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Specification