Accepting user input is a key requirement of human interface systems that incorporate graphical displays. Designs today tend to feature more stylish and elegant touch-sensing interfaces replacing mechanical buttons. The PIC24FJ DA family marries up its rich graphics acceleration engine with Microchip’s proven mTouch Sensing technology enabling designers to implement a single chip human interface subsystem. With this integration, designers can essentially design touch applications without needing an external touch controller. There are two types of touch sensing interfaces that are typically designed. Where pre-defined fixed-function inputs are desired, designers may implement capacitive touch keys, sliders, buttons or wheels to replace traditional switches. In applications where a more dynamic input is desired such as on-screen context-sensitive menus, touch-screens are typically implemented. Both of these types of touch-sensing interfaces, namely keys and sliders as well as touch screens are supported by the PIC24FJ DA family of devices. Resistive touch screens can be easily implemented by interfacing to the A/D converter channels on the PIC24FJ256DA210. Capacitive touch keys are implemented using a special peripheral named the Charge Time measurement Unit (CTMU). Capacitive sensing using the CTMU also enables designers to incorporate proximity detection features. This feature will help in implementing power-saving features such as turning on the display when the user is in close physical proximity and turning off the display when the system is not being used. Another key benefit of Microchip’s mTouch Sensing technology and the CTMU peripheral is the ability to use many different kinds of materials as overlays when implementing keys, sliders and wheels. mTouch sensing technology supports both plastic and metallic finishes. Metallic overlays and finishes enable the keys to be water-resistant, glove-friendly and even Braille-friendly.