ST STM32U575I-EV, User Manual, Page: 65 / 105

Table 50. CN4 EXT_I2C connector pinout
Connector pin
number
STM32 pin Board function
1 - -
2 GND Power GND
3 - -
4 VDD Power VDD
5 MFX_IO8 External reset command from MFX
6 PG7 / PB10
I
2
C SCL clock signal
7 - -
8 PG8 / PB11
I
2
C SDA data signal
7.27 Touchkey button
7.27.1 Description
The STM32U575I-EV Evaluation board supports a touchkey button based on either RC charging or charge-
transfer technique. This one is enabled by default.
7.27.2 Touchkey button I/O interface
The touchkey button is connected to one of the TSC ports of STM32U575AII6Q with the related charge capacitor.
An active shield is designed in layer 2 of the main PCB, under the button footprint. It allows reducing disturbances
from other circuits to prevent false touch detections.
The active shield is connected to another TSC interface of STM32U575AII6Q through the R21 serial resistor. The
related charge capacitor is connected to the same TSC interface.
The solder bridge and jumper configuration related to the touchkey function enables or disables its operation.
However, most of them serve to optimize the touchkey performance, by isolating copper tracks to avoid
disturbances due to their antenna effect.
For more information about the TSC interface and the tuning explanation for this interface, refer to the application
note
Getting started with touch sensing control on STM32 microcontrollers ( AN5105 ) and the STM32U5xx product
datasheets.
STM32U575I-EV
Touchkey button
UM2854 - Rev 1
page 65/105