New capacitive touch sensing solution from Cypress, and now from Texas Instruments. (New app notes).
Few months ago Cypress Semiconductor introduced new CapSense Demo Board based on their PSoC microcontrollers. Basic idea is to replace mechanical components like buttons, sliders and touchpads with more economical and reliable parts. Although it is probably more reliable than mechanical switches, the economical issues are not so obvious.
CapSense technology is based on buttons and sliders made directly on PCBs. Sensing elements are built with traces and gaps between them. Application note AN2292 gives PCB layout guidelines. The AN2233a application note outlines theory, design techniques and implementation with PSoC microcontrollers. In the AN2277 is described the Capacitive Front Panel Display demonstration board, its layout, firmware, and features.
Texas Instruments recently released an application report SLA363 “PCB-Based Capacitive Touch Sensing With MSP430″. In this application report, the design of a capacitive touch sensor interface using the MSP430 microcontroller is dicussed. This application report provides an overview of the technology, and details for different methodologies of capacitive touch sensing implementations using the MSP430 family. Main idea is rather similar to that explained in the Cypress app notes.