Ultralow Power Comparators And Reference Voltage; Routing Interface; Touch Sensing - STMicroelectronics STM32L151CB Manual

STM32L151x6/8/B, STM32L152x6/8/B
This dual digital Interface supports the following features:
•
two DAC converters: one for each output channel
•
left or right data alignment in 12-bit mode
•
synchronized update capability
•
noise-wave generation
•
triangular-wave generation
•
dual DAC channels' independent or simultaneous conversions
•
DMA capability for each channel (including the underrun interrupt)
•
external triggers for conversion
• input reference voltage V
Eight DAC trigger inputs are used in the STM32L15xx6/8/B. The DAC channels are
triggered through the timer update outputs that are also connected to different DMA
channels.
3.12

Ultralow power comparators and reference voltage

The STM32L15xx6/8/B embeds two comparators sharing the same current bias and
reference voltage. The reference voltage can be internal or external (coming from an I/O).
•
one comparator with fixed threshold
•
one comparator with rail-to-rail inputs, fast or slow mode. The threshold can be one of
the following:
–
–
–
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).
3.13

Routing interface

This interface controls the internal routing of I/Os to TIM2, TIM3, TIM4 and to the
comparator and reference voltage output.
3.14

Touch sensing

The STM32L15xx6/8/B devices provide a simple solution for adding capacitive sensing
functionality to any application. These devices offer up to 20 capacitive sensing channels
distributed over 10 analog I/O groups. Only software capacitive sensing acquisition mode is
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
REF+
DAC output
External I/O
Internal reference voltage (V
DocID17659 Rev 10
) or V submultiple (1/4, 1/2, 3/4)
REFINT REFINT
Functional overview
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