SLAU857A May   2021  – July 2021 MSP430FR2476 , MSP430FR2512 , MSP430FR2522 , MSP430FR2532 , MSP430FR2533 , MSP430FR2632 , MSP430FR2633 , MSP430FR2672 , MSP430FR2673 , MSP430FR2675 , MSP430FR2676

 

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2 Principles of Capacitive Touch

Figure 2-1 shows a common capacitive touch sensor. Sensors typically use copper on the PCB as electrodes. The top layer is covered with a nonconductive protective layer, such as glass or plastic, and glued to the PCB. A grid ground surrounds the sensor.

GUID-20210517-CA0I-TGQG-K3WX-1PJ7WDJTCZN6-low.pngFigure 2-1 Capacitive Touch Structure

Based on the type of capacitance detected, capacitive touch can be described as self-capacitive detection (detecting the capacitance value between a single electrode and power line ground) or mutual-capacitive detection (detecting the capacitance value between two electrodes).