Microchip Technology Inc.

Burke Davison

Yann LeFaou

Keith Edwin Curtis

Sean Steedman

Zeke Lundstrum

Xiang Gao

Stephen B Porter

Aurelian Floricica-Voicu

Andrew Voris

Yann Lefaou

In a method for performing a touch determination with a capacitive sensor, a self capacitance measurement of a capacitive sensor is initiated, wherein at the same time a mutual capacitance measurement including the capacitive sensor is performed. Such a method can be performed such that the self capacitance measurement and the mutual capacitance measurement differentially cancel with ungrounded conductive objects approaching or touching the capacitive sensor and additively combine for grounded objects approaching or touching the capacitive sensor.

Analog elimination of ungrounded conductive objects in capacitive sensing

A system for reducing noise in a sensor measurement system includes a noise detector for detecting noise in capacitive to digital conversion measurements; a noise correction module operably coupled to the noise detector and configured to dynamically modify one or more delays associated with a sampling waveform; and a noise filter for filtering the sampling waveform.

Noise detection and correction routines

A microcontroller measures capacitance of capacitive sensors having guard rings associated therewith. A guard ring is provided around each capacitive sensor plate and is charged to substantially the same voltage as a voltage on the associated capacitive sensor plate. The guard ring reduces parasitic capacitances of the capacitive sensor plate caused by differences in voltage potentials between the capacitive sensor plate, and adjacent circuit conductors, ground planes and power planes. An analog output is buffered and coupled to an analog input coupled to the capacitive sensor plate, and is used to drive the guard ring voltage to substantially the same voltage as the voltage on the capacitive sensor plate.

Measuring capacitance of a capacitive sensor with a microcontroller having an analog output for driving a guard ring

A guard ring is provided around each capacitive sensor plate and charged to substantially the same voltage as a voltage on the capacitive sensor plate. The guard ring reduces parasitic capacitances of the capacitive sensor plate caused by differences in voltage potentials between the capacitive sensor plate, and adjacent circuit conductors, ground planes and power planes. Two digital outputs and associated voltage divider resistors are used to drive the guard ring voltage to substantially the same voltage as the voltage on the capacitive sensor plate.

Measuring capacitance of a capacitive sensor with a microcontroller having digital outputs for driving a guard ring

An analog-to-digital (ADC) controller is used in combination with a digital processor of a microcontroller to control the operation of capacitance measurements using the capacitive voltage division (CVD) method. The ADC controller handles the CVD measurement process instead of the digital processor having to run additional program steps for controlling charging and discharging of a capacitive touch sensor and sample and hold capacitor, then coupling these two capacitors together, and measuring the resulting voltage charge thereon in determining the capacitance thereof. The ADC controller may be programmable and its programmable parameters stored in registers.

Microcontroller with optimized ADC controller

An automated sequencer for a microcontroller is provided which makes a CVD conversion process a hardware function. The sequencer controls the charging/discharging of the sensor and ADC sample-and-hold capacitances, as well as the voltage division process. It also initiates the ADC conversion, with an optional second conversion for greater resolution, or a differential conversion.

Microcontroller with sequencer driven analog-to-digital converter

An ADC module includes an analog to digital converter coupled with an analog bus, wherein the an analog to digital converter comprises a main sample and hold capacitor; and a plurality of additional sample and hold capacitances which can be programmably coupled in parallel with said main sample and hold capacitance.

Microcontroller ADC with a variable sample and hold capacitor

Systems and methods for determining a user's touch in a capacitive touch sensor system is provided, including performing a series of potential touch detection tests for a plurality of sensors until a potential touch is detected and measuring a test frequency for one of the sensors, such that a potential touch may be detected when the measured test frequency deviates from a previously measured test frequency for the same sensor. After detecting a potential touch, the method may additionally include performing a series of baseline comparison tests for each of the sensors, for example, measuring a current frequency for one of the sensors, comparing the current frequency to a baseline frequency, and assigning a deviation value based on the comparison the current frequency and the baseline frequency. The method may identify the sensor with the largest deviation value as a touched sensor.

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Chandler, AZ, United States of America

Burke Davison