Silicon Labs created interest in capacitive touch sensing solutions with the launch of the C8051F700 family of microcontrollers in early 2009. These MCUs were the first in the industry to include a 16-bit hardware capacitive-to-digital converter module, optimized for capacitive touch sensing applications. The C8051F700 MCUs have since been adopted for both capacitive buttons and touch screen applications.  The total system solution from Silicon Labs (including semiconductors, integrated development environment and software libraries) has now been enhanced with the addition of a ‘baselining’ function to the Silicon Labs QuickSense™ firmware API.

Baselining is a method of adjusting capacitance measurements to compensate for changes in environmental and operating conditions. Some environmental effects include temperature or humidity changes. For example, a change in operating conditions includes calibration of a capacitive sense channel by someone with an ungloved hand that would later be used by someone with a gloved hand. The baselining function in the QuickSense™ firmware API compares the runtime baseline values to calibrated reference baseline values in order to calculate the offset and adjust accordingly. See the diagram illustrating this operation.  More details can be found in application note.