A solder bridge (SB18) is used to disconnect the LDO output when an external 1V8 is applied to the Nucleo
board:
• SB18 ON: U9 LDO output provides a 1V8 power supply (default configuration).
• SB18 OFF: U9 LDO output does not provide 1V8. An external 1V8 is needed.
6.4.5 VDD_MCU IDD measurement
The labeled VDD_MCU jumper (JP2) can measure the consumption of the STM32 microcontroller by replacing
the jumper with an ammeter or a current measurement tool:
• Jumper ON: The STM32 microcontroller is powered (default).
• Jumper OFF: An ammeter or an external 3V3 power source must be connected to the power and
measures the STM32 microcontroller consumption.
The jumper can measure the current for both 3V3 and 1V8 MCU voltage ranges.
6.5 LEDs
User green LED (LD1)
The user green LED (LD1) is connected to the PD10 STM32 I/O (SB50 ON and SB49 OFF, default configuration)
or PA5 (SB50 OFF and SB49 ON, optional configuration corresponding to the D13 ST Zio expansion connector).
A transistor is used to drive the LED whatever the MCU 1V8 or 3V3 voltage range is.
User yellow LED (LD2)
The user yellow LED (LD2) is connected to PD13. A transistor is used to drive the LED whatever the MCU 1V8 or
3V3 voltage range is.
User red LED (LD3)
The user red LED (LD3) is connected to PB7. A transistor is used to drive the LED whatever the MCU 1V8 or 3V3
voltage range is.
These user LEDs are ON when the I/O is in the HIGH state, and are OFF when the I/O is in the LOW state.
USB Type-C
®
green LED (LD4)
The green LED (LD4) shows the presence of the VBUS on CN2. Refer to Section 6.12: USB Type-C
®
(HS, DRP)
for more details.
Green PWR LED (LD5)
The green LED (LD5) indicates that the STM32 part is powered by a 5V source. It also indicates the power source
of the user USB connector (CN2) when it is used as the source port.
Tricolor COM LED (LD8)
The tricolor (green, orange, and red) LED (LD8) provides information about the STLINK-V3EC communication
status. The LD8 default color is red. LD8 turns green to indicate that the communication is in progress between
the PC and STLINK-V3EC, with the following setup:
• Red: When the initialization between the PC and STLINK-V3EC is complete
• Green: After a successful target communication initialization
• Red/green fast blinking: During communication with the target
• Orange: Communication failure
UM3276
Hardware layout and configuration
UM3276 - Rev 1
page 20/40
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