Datasheet

Functional overview STM32L073xx
30/137 DocID027096 Rev 2
3.16 Touch sensing controller (TSC)
The STM32L073xx provide a simple solution for adding capacitive sensing functionality to
any application. These devices offer up to 24 capacitive sensing channels distributed over 8
analog I/O groups.
Capacitive sensing technology is able to detect the presence of a finger near a sensor which
is protected from direct touch by a dielectric (such as 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. 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 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.
Table 9. Capacitive sensing GPIOs available on STM32L073xx devices
Group
Capacitive sensing
signal name
Pin
name
Group
Capacitive sensing
signal name
Pin
name
1
TSC_G1_IO1 PA0
5
TSC_G5_IO1 PB3
TSC_G1_IO2 PA1 TSC_G5_IO2 PB4
TSC_G1_IO3 PA2 TSC_G5_IO3 PB6
TSC_G1_IO4 PA3 TSC_G5_IO4 PB7
2
TSC_G2_IO1 PA4
6
TSC_G6_IO1 PB11
TSC_G2_IO2 PA5 TSC_G6_IO2 PB12
TSC_G2_IO3 PA6 TSC_G6_IO3 PB13
TSC_G2_IO4 PA7 TSC_G6_IO4 PB14
3
TSC_G3_IO1 PC5
7
TSC_G7_IO1 PC0
TSC_G3_IO2 PB0 TSC_G7_IO2 PC1
TSC_G3_IO3 PB1 TSC_G7_IO3 PC2
TSC_G3_IO4 PB2 TSC_G7_IO4 PC3
4
TSC_G4_IO1 PA9
8
TSC_G8_IO1 PC6
TSC_G4_IO2 PA10 TSC_G8_IO2 PC7
TSC_G4_IO3 PA11 TSC_G8_IO3 PC8
TSC_G4_IO4 PA12 TSC_G8_IO4 PC9
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