ST Nucleo-64 STM32WL3 Series User Manual page 13

7.1.4 Current measurement
As the device has low‑power features, it can be interesting to measure the current consumed by STM32WL33CC.
The board offers an IDD jumper JP2 for easy measurement.
Set JP2 OFF and insert an ammeter at this place. This measures only the STM32WL3x current consumption.
7.1.5 SW1 switch use
SW1 is a two‑position switch used to select if the STM32WL33CC is supplied by onboard 3V3V LDO or an
external power source.
1. Position [1-2]: It is the default position. The voltage source is the U4 LDO providing 3.3 V.
2. Position [3-2]: The external sources might be applied on VEXT on CN10, ST morpho 5VEXT, or ARDUINO
VIN. The externally applied voltages must be in the range of STM32WL33CC supply: 1.7 to 3.6 V. Refer to
solder bridge configurations of SB21, SB22, and SB23 given your use case.
7.2 Clock sources
7.2.1 HSE clock references
The high‑speed clock (HSE) of the MCU RF board is a 48 MHz crystal unit. The internal capacitor bank of
STM32WL33CC can be used to trim this frequency.
7.2.2 LSE clock references
The low‑speed clock (LSE) of the MCU RF board is a 32.768 kHz crystal unit.
7.3 Reset sources
The reset signal of NUCLEO-WL33CCx is active LOW. The internal PU forces the RST signal to a high level. The
sources of reset are:
• The reset push-button (B4)
• The embedded STLINK-V3
• The ARDUINO
• The ST morpho connector (CN3 pin 14)
UM3418 - Rev 1
Figure 8.
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connector (CN5 pin 3)
Hardware layout and configuration
SW1 default setting
UM3418
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