Capacitance Sensing Using Microcontroller ADC and Switches
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Solution Overview
Problem
There is a need for more flexible and easily integratable capacitance sensing methods and devices, particularly for microcontroller devices, to accurately determine changes in capacitance values, such as in touch sensing applications.
Innovation Solution
A microcontroller with an analog-to-digital converter and a limit checker, along with switching elements, alternately charges and discharges capacitance to generate a switching signal, allowing for the detection of capacitance changes based on oscillation parameters like frequency or period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional capacitance sensing methods are used, then capacitance detection can be achieved, but the integration into microcontroller devices is complex and inflexible
Solution Approach 1:
The patent combines the capacitance sensing function with standard microcontroller components (ADC, limit checker, switches) that are already present in most microcontroller devices. By merging the sensing function with existing infrastructure, the patent achieves easy integration without adding significant complexity.
Solution Approach 2:
The patent creates a universal capacitance sensing method that can be applied to various touch sensing applications using standard microcontroller components. The method uses general-purpose ADC, switches, and limit checkers that can serve multiple functions, making the sensing system adaptable and versatile across different applications.
2Measurement precision
If precise capacitance measurement is implemented, then accurate touch detection is achieved, but the system requires complex external circuitry
Solution Approach 1:
The patent makes the microcontroller's own components serve the capacitance sensing function. The ADC, switches, and limit checker - which are standard parts of the microcontroller - are utilized for sensing, eliminating the need for complex external circuitry while maintaining measurement precision.
Solution Approach 2:
The patent replaces complex external sensing circuitry with software-controlled operations using standard microcontroller components. The capacitance sensing is achieved through programmed switching and ADC readings rather than dedicated hardware circuits, simplifying the overall system.
3Reliability
If oscillation-based capacitance sensing is used, then capacitance changes can be detected, but the system requires additional oscillation circuitry
Solution Approach 1:
The patent merges the oscillation generation function with the existing ADC and switching components. The oscillation is created by alternately charging and discharging the capacitance through the switches, using the ADC to detect the oscillation state, thereby eliminating the need for separate oscillation circuitry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise and flexible capacitance sensing, allowing for the determination of capacitance values and changes, which is essential for touch sensing applications, and can be easily integrated into microcontroller devices.
Implementation Method 1
an analog-to-digital converter (102) to provide a digital value based on an analog input signal
Implementation Method 2
at least one switch (110) alternately coupling the first input to a first potential (112a) for charging the capacitance and to a second potential (112b) for discharging the capacitance
Data Source
AI summary
Embodiments related to sensing a capacitance are described and depicted.