9.4.6.15.2 4-wire Resistive Touchscreen Principles

A resistive touchscreen is based on two resistive films, each one being fitted with a pair of electrodes, placed at the top and bottom on one film, and on the right and left on the other. In between, there is a layer acting as an insulator, but also enables contact when you press the screen. This is illustrated in the following figure.

The ADC Controller can perform the following tasks without external components:

position measurement
pressure measurement
pen detection

Figure 9-38. Touchscreen Position Measurement

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