ST Nucleo-64 STM32U3 User Manual page 28

External oscillator to PH0 input (default: not connected)
The input clock comes from an external oscillator through PH0, CN17 pin 29. The following configuration is
needed:
• SB19 and SB21 ON. PH0 and PH1 are connected to CN7 (PH1 can be used as a GPIO).
• SB20 OFF. MCO is not connected to PH0.
• SB3 and SB4 OFF. The external crystal is disconnected from PH0 and PH1.
HSE not used (default configuration)
PH0 and PH1 are used as GPIOs instead of crystal input. The following configuration is needed:
• SB19 and SB21 ON. PH0 and PH1 are connected to expansion connector CN7 as GPIOs.
• SB20 OFF. MCO is not connected to PH0.
• SB3 and SB4 OFF. The external crystal X2 is disconnected from PH0 and PH1.
7.8 Reset sources
The reset signal NRST of the Nucleo-64 board is active LOW and the reset sources come from:
• The RESET button (B2)
• The embedded STLINK-V3EC (CN1)
• The ARDUINO
• The ST morpho connector (CN7 pin 14)
7.9 Virtual COM port (VCP)
An STM32 serial interface is connected to the STLINK-V3EC debug interface. The user can choose between a
USART or an LPUART interface.
The selection between USART and LPUART is performed by setting related solder bridges.
Refer to the two tables below to set the USART or LPUART connection to the VCP interface.
ST-LINK and ARDUINO
configuration
USART1 (PA9/PA10) connected
to STLINK-V3EC VCP
and
LPUART1 (PA2/PA3) connected
®
to ARDUINO
LPUART1 (PA2/PA3) connected to
STLINK-V3EC VCP
and
USART1 (PA9/PA10) connected to
®
ARDUINO Uno V3 D0/D1
1. The default configuration is in bold.
By default:
• The serial communication between the target MCU and ST-LINK MCU is enabled on USART1 because this
interface supports Bootloader mode.
• The serial communication between the target MCU and ARDUINO
enabled on LPUART1, not to interfere with the VCP interface.
UM3062 - Rev 2
®
connector (CN6 pin 3)
Table 9.
®
UART
Solder bridge configuration
SB15, SB17, SB35, and SB37
ON
SB16, SB26, SB34, and SB36
OFF
Uno V3 D0/D1
SB16, SB26, SB34, and SB36 ON
SB15, SB17, SB35, and SB37
OFF
USART1 LPUART1 connection
(1)
USART1 (PA9/PA10) connected to STLINK-V3EC
VCP
LPUART1 (PA2/PA3) connected to ARDUINO
Uno V3 D0/D1
LPUART1 (PA2/PA3) connected to STLINK-V3EC
VCP
USART1 (PA9/PA10) connected to ARDUINO
V3 D0/D1
®
UM3062
Hardware layout and configuration
Feature
Uno V3 or ST morpho connector is
®
®
Uno
page 28/47