Overview: TouchXpress™ Family CPT212B Data Sheet The CPT212B device, part of the TouchXpress family, is designed to quickly add capacitive touch via an I2C interface by eliminating the firmware plexity and reducing the development time for capacitive sensing applications. Supporting up to 12 capacitive sensor inputs in packages as small as a 3 mm x 3 mm QFN, the CPT212B is a highly-integrated device that interfaces via I2C to the host processor to provide a simple solution for adding capacitive touch.