CPT112S TouchXpress Capacitive Touch Controllers Silicon Labs CPT112S TouchXpress™ Capacitive Touch Controllers are highly integrated devices that offer a simple solution for adding capacitive touch in new and legacy systems. These CPT112S controllers support up to 12 capacitive sensor inputs and use an I²C interface to communicate to the host processor. As part of the TouchXpress family, the CPT112S is designed to make it easy to replace mechanical buttons with capacitive touch buttons.