Datasheet

STM32F313xx Functional overview
Doc ID 023636 Rev 1 25/58
variation introduced by the finger (or any conductive object) is measured using a proven
implementation based on a surface charge transfer acquisition principle. It consists of
charging the electrode capacitance and then transferring a part of the accumulated charges
into a sampling capacitor until the voltage across this capacitor has reached a specific
threshold. To limit the CPU bandwidth usage this acquisition is directly managed by the
hardware touch sensing controller and only requires few external components to operate.
The STM32F313xx devices offer up to 23 capacitive sensing channels distributed over 8
analog I/O groups.
The touch sensing controller is fully supported by the STMTouch touch sensing firmware
library which is free to use and allows touch sensing functionality to be implemented reliably
in the end application.