The idea of Cypress CapSense is to measure the parasitic capacitance of the sensor and converts it into a number. We call that number as raw counts. Based on the value of raw counts the parasitic capacitance can be estimated. So in your case in order to detect the pressure you should convert the pressure to capacitance. For that we recommend you to use a flexible dielectric so that when touched with more force the effective distance between the finger and overlay decreases and the raw counts increases. In this way you can detect pressure using CapSense. So please go through the PSoC 4 capSense design guide to design the application with a flexible overlay.
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