Datasheet

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STM32L15xCC STM32L15xRC STM32L15xUC STM32L15xVC Functional overview
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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 interface).
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 STM32L15xxC 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.
3.16.1 General-purpose timers (TIM2, TIM3, TIM4, TIM5, TIM9, TIM10 and
TIM11)
There are seven synchronizable general-purpose timers embedded in the STM32L15xxC
devices (see Table 7 for differences).
TIM2, TIM3, TIM4, TIM5
TIM2, TIM3, TIM4 are based on 16-bit auto-reload up/down counter. TIM5 is based on a 32-
bit auto-reload up/down counter. They include a 16-bit prescaler. They feature four
independent channels each for input capture/output compare, PWM or one-pulse mode
output. This gives up to 16 input captures/output compares/PWMs on the largest packages.
TIM2, TIM3, TIM4, TIM5 general-purpose timers can work together or with the TIM10,
TIM11 and TIM9 general-purpose timers via the Timer Link feature for synchronization or
event chaining. Their counter can be frozen in debug mode. Any of the general-purpose
timers can be used to generate PWM outputs.
Table 7. Timer feature comparison
Timer
Counter
resolution
Counter type Prescaler factor
DMA
request
generation
Capture/compare
channels
Complementary
outputs
TIM2,
TIM3,
TIM4
16-bit
Up, down,
up/down
Any integer between
1 and 65536
Yes 4 No
TIM5 32-bit
Up, down,
up/down
Any integer between
1 and 65536
Yes 4 No
TIM9 16-bit
Up, down,
up/down
Any integer between
1 and 65536
No 2 No
TIM10,
TIM11
16-bit Up
Any integer between
1 and 65536
No 1 No
TIM6,
TIM7
16-bit Up
Any integer between
1 and 65536
Yes 0 No