ST Nucleo-64 STM32U3 User Manual page 26

7.5 LEDs
STLINK-V3EC tricolor LEDs (LD1 and LD4)
The tricolor (green, orange, and red) LEDs provide information about STLINK-V3EC communication status (LD1)
and power status (LD4). For detailed information about these LEDs, refer to the technical note Overview of ST-
LINK derivatives (TN1235).
User green LED (LD2)
The user green LED (LD2) is connected to the STM32 I/O PA5 (SB10 ON, default configuration) also used for
®
ARDUINO D13 function. A transistor is used to drive the LED whatever the MCU 1V8 or 3V3 voltage range is.
5V PWR LED (LD3)
The green LED (LD3) indicates that the Nucleo-64 board is powered by a 5 V source. This source is available on
CN6 pin 5 and CN7 pin 18, but also for the LDO and external SMPS input.
®
USB Type-C
The green LED (LD6) shows the presence of 5 V on the USB-USER connector. Refer to
®
C FS for more details.
7.6 Push-buttons
Two buttons are available on the Nucleo-64 board.
USER button (B1)
The blue button for the user and wake‑up functions is connected to PC13 to support the default TAMPER function
or to PA0 to support the optional wake‑up function of the STM32 microcontroller. When the button is pressed the
logic state is HIGH, otherwise, the logic state is LOW.
• To connect the USER button to PC13, SB24 must be ON and SB23 must be OFF. This is the default
configuration.
• To connect the USER button to PA0, SB24 must be OFF and SB23 must be ON. This is the optional
configuration.
The USER button is implemented using a firmware debounce filter. This helps to reduce the BOM cost by
removing the external hardware debounce filter R48 and C72.
Warning:
RESET button (B2)
The black button connected to NRST is used to reset the STM32 microcontroller. When the button is pressed the
logic state is LOW, otherwise, the logic state is HIGH.
The blue and black plastic hats placed on these push-buttons can be removed if necessary when a shield or an
application board is plugged into the top of the Nucleo-64 board. This avoids pressure on the buttons and
consequently a possible permanent target MCU reset.
UM3062 - Rev 2
LED (LD6)
PC13 I/O used for the USER button must be set in INPUT, pull
Never set the PC13 in OUTPUT level LOW to avoid a shortcut when the USER button is
pressed.
UM3062
Hardware layout and configuration
Section 7.11: USB Type-
‑ down (PD) with debouncing.
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