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3 Step 1: Understand the Basics of Capacitive Touch Sensing and CapTIvate Technology

The first step of designing a successful capacitive touch sensing system is to understand the basic principles of capacitive touch sensing. Capacitive sensing performs a measurement to detect a change in the capacitance of a sensor element. A sensor element can be any conductive material (for example, a copper PCB plane or a wire). The change can be due to human interaction, such as a finger, ear, or hand. This is often termed capacitive touch, and Figure 2 shows the stackup of a basic capacitive touch design.

For additional information, visit Capacitive Sensing Basics.

stack-up-of-basic-capacitive-touch.pngFigure 2. Stackup of Basic Capacitive Touch Design

Two different capacitive sensing measurement methods are available: self capacitance and mutual capacitance. Table 1 compares these two sensing measurement methods. Review the fundamentals of these two sensing methods to choose the one that best suits the application requirements. CapTIvate MCUs support both sensing methods in a single design.

For additional information, visit these topics:

Table 1. Comparison of Self Capacitance and Mutual Capacitance

Characteristic Self Capacitance Mutual Capacitance
Sensor layout Simpler More complex
Allow overlay air gap Yes No
Number of PCB layers Typically 1 or 2 Typically 2
Pins required for 12 buttons 12 7 (3 TX and 4 RX)

At this point, you should have a good understanding of the capacitive touch sensing fundamentals. Refer to these topics to find out how TI CapTIvate technology applies these fundamentals: