Programming/Debugging When The Power Supply Is Not From Stlink-V2Ec (Stlk); Power Supply Output - ST STM32 User Manual

The STM32 Nucleo-64 board and its shield can be powered via the STLINK-V2EC connector (CN1). However,
only the STLINK-V2EC circuit is powered before USB enumeration because the host PC only provides 100 mA to
the board at that time. During the USB enumeration, the STM32 Nucleo-64 board requires 500 mA of current from
the host PC.
• If the host can provide the required power, the enumeration ends by a SetConfiguration command. Then,
the power transistor is switched ON and the green LED (LD3) is turned ON. Thus, the STM32 Nucleo-64
board and its shield request no more than 500 mA current.
• If the host is not able to provide the required current, the enumeration fails. Therefore, the power switch
stays OFF and the MCU part including the extension board is not powered. As a consequence, the green
LED (LD3) stays turned OFF. In this case, it is mandatory to use an external power supply.
VIN is the 7 to 12 V DC power from the ARDUINO
In this case, the JP1 jumper must be on [3-4] to select the VIN power source. In that case, the DC power comes
from the ARDUINO
An LDO (U10) is used to provide a fixed 5 V from VIN (7 to 12 V).
5V_EXT is the DC power coming from an external 5 V DC power source from the ST morpho connector (CN7 pin
6). The 5V jumper selection (JP1) must be on [5-6] to select the 5V_EXT power source.
5V_USB is a 5 V DC power with limitations from the USB Type-C
selection (JP1) must be on [7-8] to select the USB power source on the JP1 connector.
External 3V3 power supply input. It is sometimes interesting to use an external 3.3 V source on the 3V3 input
(CN6 pin 4 or CN7 pin 16). It is the case when an expansion board provides 3.3 V. When the Nucleo-64 is
powered with only a 3.3 V source, STLINK-V2EC is not powered thus programming and debugging are
unavailable. When using the 3V3 input, the STLINK-V2EC part is not supplied for this configuration. To prevent
unintentional feedback of 5 V via component U9, ST recommends removing component SB2 from the circuit.
VDD power supply input. In some situations, it is interesting to use an external power source from 1.71 to 3.6 V
to power only the MCU power supply pins (JP5 pin 1). In this configuration, external functions like debug, LED, or
expansion connector are not powered. This option can be used to optimize MCU power consumption
measurement.
6.4.2

Programming/debugging when the power supply is not from STLINK-V2EC (STLK)

In case the current consumption of the Nucleo-64 and the expansion boards exceeds the allowed current on the
ST-LINK USB connector, the external power VIN, 5V_EXT, or 5V_USB can be used. In such a case, it is still
possible to use the embedded ST-LINK for VCP programming and debugging. In this case, the following power
sequence procedure must be respected:
1. Set the JP1 jumper according to the 5 V selected external power source.
2. Connect the external power source according to JP1.
3. Power on the external power supply.
4. Check that the 5 V green LED (LD3) is turned ON.
5. Connect the PC to the USB connector (CN1) for programming/debugging.
If this sequence is not followed, the STLINK-V2EC V
risks might be encountered:
• If the board requires at least 500 mA, this might damage the PC, or the PC might limit the current.
Therefore, the board is not powered correctly.
• 500 mA is requested at enumeration: This request is rejectable and the enumeration does not succeed if
the PC does not provide such a current. Consequently, the board is not power supplied (LED LD3 remains
OFF).
6.4.3

Power supply output

• 5V: Whatever the power source is (STLK, VIN, 5V_EXT, or 5V_USB), the 5 V generated is present on CN6
pin 5 or CN7 pin 18. It can be used as an output power supply for an ARDUINO
board. In this case, the maximum current of the power source specified in
• 3V3: The internal 3V3, on CN6 pin 4 or CN7 pin 16, can be used also as a power supply output. The
current is limited by the maximum current capability of the U9 regulator (500 mA maximum concerning the
STM32 Nucleo-64 board with shields consumption).
UM3353 - Rev 1
®
Uno V3 battery shield and is compatible with the Adafruit
®
connector (CN6) pin 8, or ST morpho connector (CN7) pin 24.
®
®
connector (CN13). In this case, the 5V jumper
might first supply power to the board, and the following
BUS
UM3353
Hardware layout and configuration
PowerBoost 500 shield.
®
shield or an extension
Table 6 needs to be respected.
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