ST NUCLEO-WL55JC STM32WL User Manual

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6.5.2 LSE clock (low-speed external clock) – 32.768 kHz

There are three ways to configure the pins corresponding to the low-speed clock (LSE):

• On-board oscillator (Default): X2 crystal. Refer to the Oscillator design guide for STM8S, STM8A

and STM32 microcontrollers application note (AN2867) as the oscillator design guide for STM32

microcontrollers. It is recommended to use NX3215SA-32.768kHz-EXS00A-MU00527 (32.768 kHz, 6 pF

load capacitance, 20 ppm) from NDK.

– SB11 and SB14 OFF

– SB12 and SB13 ON

• Oscillator from external PC14: from external oscillator through the pin 25 of CN7 connector. The

configuration must be:

– SB11 (and SB14 ON, but not necessary)

– SB12 and SB13 OFF

• LSE not used: PC14 and PC15 are used as GPIOs instead of the low-speed clock. The configuration must

be:

– SB11 and SB14 ON (to get them on CN7)

– SB12 and SB13 OFF

6.6 Board functions

6.6.1 LEDs

LED1 (USER LED)

This blue LED is a user LED connected to STM32WL I/O PB15. To light the LED LED1, a high-logic state “1” has

to be written in the corresponding GPIO PB15.

LED2 (USER LED)

This green LED is a user LED connected to STM32WL I/O PB9. To light the LED LED2, a high-logic state “1” has

to be written in the corresponding GPIO PB9.

LED3 (USER LED)

This red LED is a user LED connected to STM32WL I/O PB11. To light the LED LED3, a high-logic state “1” has to

be written in the corresponding GPIO PB11.

LED4 USB power fault (OC, overcurrent)

LED4 indicates that the board power consumption on USB ST-LINK exceeds 500 mA, consequently the user

must check the root cause of the overconsumption or power the board using an external power supply.

LED5 (5V_PWR)

The green LED indicates that the STM32WL part is powered and +5 V power is available on CN6 pin 5 and CN7

pin 18 if the jumper JP7 is fitted.

LED6 (STLINK-V3 COM LED)

The bicolor LED LED6 (green, red) provides information about STLINK-V3E communication status. LED6

indicates the communication progress between the PC and the STLINK-V3E, with the following setup:

• Blinking red: the first USB enumeration with the PC is taking place

• Red LED ON: when the initialization between the PC and STLINK-V3E is complete

• Blinking red or green: during programming and debugging with target

• Green LED ON: communication finished and successful

• Orange ON: communication failure

UM2592

Board functions

UM2592 - Rev 1

page 25/49

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ST NUCLEO-WL55JC STM32WL Specifications

General

Microcontroller	STM32WL55JC
Flash Memory	256 KB
RAM/SRAM	64 KB
Operating Frequency	Up to 48 MHz
On-board debugger	ST-LINK/V2-1
ADC	12-bit, up to 16 channels
Wireless Technology/Radio	LoRa, (G)FSK, (G)MSK, BPSK
Operating Voltage	1.7 V to 3.6 V
DAC	12-bit
Communication Interfaces	SPI, I2C, USART
Operating Temperature	-40 °C to +85 °C