STMicroelectronics Nucleo Development Board for STM32 Microcontrollers NUCLEO-F103RB NUCLEO-F103RB Data Sheet

DocID025833 Rev 3

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It can be of interest to use the +3V3 (CN6 pin 4 or CN7 pin 12 and pin 16) directly as power 
input for instance in case the 3.3

 

V is provided by an extension board. When NUCLEO is 

power supplied by +3V3, the ST-LINK is not powered thus the programming and debug 
features are unavailable. The external power sources +3.3V is summarized in the 

 

          

Two different configurations are possible to use +3V3 to power the board:


ST-LINK is removed (PCB cut), or



SB2 (3V3 regulator) & SB12 (NRST) are OFF. 

When powered by USB, VIN or E5V, the +5V (CN6 pin 5 or CN7 pin 18) can be used as 
output power supply for an Arduino shield or an extension board. In this case, the maximum 
current of the power source specified in 

The +3.3

 

V (CN6 pin 4 or CN7 pin 12 & 16) can be used also as power supply output. The 

current is limited by the maximum current capability of the regulator U4 (500

 

mA max).

The tricolor LED (green, orange, red) LD1 (COM) provides information about ST-LINK 
communication status. LD1 default color is red. LD1 turns to green to indicate that 
communication is in progress between the PC and the ST-LINK/V2-1, with the following 
setup:


Slow blinking Red/Off: at power-on before USB initialization



Fast blinking Red/Off: after the first correct communication between the PC and ST-
LINK/V2-1 (enumeration)



Red LED On: when the initialization between the PC and ST-LINK/V2-1 is complete 



Green LED On: after a successful target communication initialization



Blinking Red/Green: during communication with target



Green On: communication finished and successful.



Orange On: Communication failure

 

User LD2: the green LED is a user LED connected to Arduino signal D13 corresponding to 
MCU I/O PA5 (pin 21) or PB13 (pin 34) depending on the STM32 target. Please refer to 



When the I/O is HIGH value, the LED is on.



When the I/O is LOW, the LED is off.

LD3 PWR: the red LED indicates that the MCU part is powered and +5V power is available.

+3V3

CN6 pin 4
CN7 pin 12 and pin 16

3  V to 3.6

 

V

Used when ST-LINK part of PCB is cut 
or SB2 and SB12 OFF