System Configuration Controller And Routing Interface; Touch Sensing; Timers And Watchdogs - STMicroelectronics STM32L151CCT6 Manual

Functional overview
Both comparators can wake up from Stop mode, and be combined into a window
comparator.
The internal reference voltage is available externally via a low-power / low-current output
buffer (driving current capability of 1 µA typical).
3.14

System configuration controller and routing interface

The system configuration controller provides the capability to remap some alternate
functions on different I/O ports.
The highly flexible routing interface allows the application firmware to control the routing of
different I/Os to the TIM2, TIM3 and TIM4 timer input captures. It also controls the routing of
internal analog signals to ADC1, COMP1 and COMP2 and the internal reference voltage
V .
REFINT
3.15

Touch sensing

The STM32L151xC and STM32L152xC devices provide a simple solution for adding
capacitive sensing functionality to any application. These devices offer up to 23 capacitive
sensing channels distributed over 10 analog I/O groups. Both software and timer capacitive
sensing acquisition modes are supported.
Capacitive sensing technology is able to detect the presence of a finger near a sensor which
is protected from direct touch by a dielectric (glass, plastic...). The capacitive 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 sensor 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. The capacitive sensing acquisition only requires few external components to
operate. This acquisition is managed directly by the GPIOs, timers and analog I/O groups
(see Section 3.14: System configuration controller and routing
Reliable touch sensing functionality can be quickly and easily implemented using the free
STM32L1xx STMTouch touch sensing firmware library.
3.16

Timers and watchdogs

The ultra-low-power STM32L151xC and STM32L152xC devices include seven general-
purpose timers, two basic timers, and two watchdog timers.
Table 7 compares the features of the general-purpose and basic timers.
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STM32L151xC STM32L152xC
interface).