Cypress Semiconductor Corporation

Vibheesh Bharathan

Andrew Kinane

David Gordon Wright

Edward L Grivna

Santhosh Kumar Vojjala

Jijeesh Choorakottayil Gopinathan

Sai Prashanth Chinnapalli

Disclosed are sensing systems and methods that eliminate CPU intervention or interrupts when performing sensor scans of a touch interface, supports low power sensing operation without requiring periodic wake up of the CPU, and is scalable to multi-channel or multi-chip sensor configuration to support large touch screens or a high number of sensors. Sensor scanning is configured and controlled by an autonomous engine and comparison is completed by wake-up detection logic, operable without CPU interaction.

Systems and method for always-on sensing user interface

Disclosed are sensing systems and methods that eliminate CPU intervention or interrupts when performing sensor scans of a touch interface, supports low power sensing operation without requiring periodic wake up of the CPU, and is scalable to multi-channel or multi-chip sensor configuration to support large touch screens or a high number of sensors. A sensor scanning module may operate in a chained-scan using direct memory access (CS-DMA) mode or an autonomous scan-multiple scan (AS-MS) mode to perform scanning of all sensors within a frame without requiring CPU intervention or generating CPU interrupts after every scan in the frame. The sensor scanning module may operate autonomously in a low-power always-on scan (LP-AOS) mode for multiple frames without CPU interaction until a touch event is detected. The CPU may operate in a low power sleep mode during the scan while providing consistent refresh rate and low touch-to-system wake up latency.

Always on low power capacitive matrix autonomous scan

Apparatuses and methods of distinguishing between a finger and stylus proximate to a touch surface are described. One apparatus includes a first circuit to obtain capacitance measurements of sense elements when a conductive object is proximate to a touch surface. The apparatus also includes a second circuit coupled to the first circuit. The second circuit is operable to detect whether the conductive object activates the first sense element, second sense element, or both, in view of the capacitance measurements. To distinguish between a stylus and a finger as the conductive object, the second circuit determines the conductive object as being the stylus when the second sense element is activated and the first sense element is not activated and determines the conductive object as being the finger when the first sense element and the second sense element are activated.

Detect and differentiate touches from different size conductive objects on a capacitive button

A circuit, system, and method for converting mutual capacitance to a digital value is described. Charge packets are transferred from a mutual capacitance to a pair of integration capacitors during alternate charge and discharge cycles. The time required to bring the discharged integration capacitor to the same potential as the charged integration capacitor with a current source is measured as a single-slope analog-to-digital converter (ADC). The output of the ADC is representative of the mutual capacitance.

Quasi-differential mutual capacitance measurement

Apparatuses and methods of distinguishing between a finger and a stylus proximate to a touch surface are described. One apparatus includes a first circuit to obtain capacitance measurements of sense elements when a conductive object is proximate to a touch surface. The apparatus also includes a second circuit coupled to the first circuit. The second circuit is operable to detect whether the conductive object activates the first sense element, second sense element, or both, in view of the capacitance measurements. To distinguish between a stylus and a finger as the conductive object, the second circuit determines the conductive object as being the stylus when the second sense element is activated and the first sense element is not activated and determines the conductive object as being the finger when the first sense element and the second sense element are activated.

Apparatuses and methods of capacitive buttons and detecting and differentiating touches from different size conductive objects on the capacitive buttons. One apparatus includes a capacitance-sensing circuit coupled to a capacitive button. The capacitive button includes a first sense element and a second sense element. The capacitance-sensing circuit is operative to measure signals from the first sense element and the second sense element with a sensing parameter (also referred to as tuning properties) set to a first value. The signals correspond to capacitances of the first sense element and second sense element. An inner perimeter of the first sense element is disposed to surround (at least in part) an outer perimeter of the second sense element. The apparatus further includes processing logic coupled to the capacitance-sensing circuit. The processing logic is operative to detect whether the first sense element is activated by a conductive object proximate to the capacitive button based on the measured signals. The processing logic detects whether the second sense element is activated by the conductive object proximate to the capacitive button based on the measured signals. The processing logic adjusts the first value to a second value for the sensing parameter when the second sense element is activated and the first sense element is not activated. The capacitance-sensing circuit is operative to measure an additional signal from the second sense element with the sensing parameter set to the second value when the second sense element is activated and the first sense element is not activated.

An apparatus includes multiple capacitive sensing elements coupled through a filter network. The apparatus can include a control device configured to excite the capacitive sensing elements with different scanning frequencies and determine capacitances corresponding to each of the capacitive sensing elements based on sensor responses to the excitation of the capacitive sensing elements with the different scanning frequencies and a configuration of the filter network.

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San Jose, CA, United States of America

Vibheesh Bharathan