Both comparators can wake up from Stop mode, and be combined into a windowcomparator.The internal reference voltage is available externally via a low power / low current outputbuffer (driving current capability of 1 μA typical).3.13Routing interfaceThis interface controls the internal routing of I/Os to TIM2, TIM3, TIM4 and to thecomparator and reference voltage output.3.14Touch sensingThe STM32L15xxx devices provide a simple solution for adding capacitive sensingfunctionality to any application. These devices offer up to 20 capacitive sensing channelsdistributed over 10 analog I/O groups. Only software capacitive sensing acquisition mode issupported.Capacitive sensing technology is able to detect the presence of a finger near a sensor whichis protected from direct touch by a dielectric (glass, plastic, ...). The capacitive variationintroduced by the finger (or any conductive object) is measured using a provenimplementation based on a surface charge transfer acquisition principle. It consists ofcharging the sensor capacitance and then transferring a part of the accumulated chargesinto a sampling capacitor until the voltage across this capacitor has reached a specificthreshold. The capacitive sensing acquisition only requires few external components tooperate.Reliable touch sensing functionality can be quickly and easily implemented using the freeSTM32L1xx STMTouch touch sensing firmware library.3.15Timers and watchdogsThe ultra-low-power STM32L15xxx devices include six general-purpose timers, two basictimers and two watchdog timers.Table 8 compares the features of the general-purpose and basic timer |