We do not recommend CY8C20xx6A for proximity detection. I suggest that you consider our newest PSoC4 family for CapSense Proximity detection. We have a ready to go kit, CY8CKIT-024 for this. This kit works in conjunction with either CY8CKIT-040 or CY8CKIT-042. We also have a proximity demonstration with a more economical kit CY8CKIT-049.
We understand that the newer family is suggested and more supported for prox. det. This is obvious. Nevertheless we have strong reasons for continuing to use the 20666A. The button wizard has a prox. det. button to select. I want to use it. There isn't any API (to speak of) for it. We feel you can do better.