This is the documentation for the latest (main) development branch of Zephyr. If you are looking for the documentation of previous releases, use the drop-down list at the bottom of the left panel and select the desired version.

ST Nucleo L552ZE Q


The Nucleo L552ZE Q board, featuring an ARM Cortex-M33 based STM32L552ZE MCU, provides an affordable and flexible way for users to try out new concepts and build prototypes by choosing from the various combinations of performance and power consumption features. Here are some highlights of the Nucleo L552ZE Q board:

  • STM32L552ZE microcontroller in LQFP144 package

  • Two types of extension resources:

    • Arduino Uno V3 connectivity

    • ST morpho extension pin headers for full access to all STM32 I/Os

  • On-board ST-LINK/V2-1 debugger/programmer with SWD connector

  • Flexible board power supply:

    • USB VBUS or external source(3.3V, 5V, 7 - 12V)

    • ST-Link

  • Three LEDs: USB communication (LD1), user LED (LD2), power LED (LD3)

  • Two push-buttons: USER and RESET

  • External or internal SMPS to generate Vcore logic supply

  • USB OTG full speed or device only

Nucleo L552ZE Q

More information about the board can be found at the Nucleo L552ZE Q website.


The STM32L552xx devices are an ultra-low-power microcontrollers family (STM32L5 Series) based on the high-performance Arm|reg| Cortex|reg|-M33 32-bit RISC core. They operate at a frequency of up to 110 MHz.

  • Ultra-low-power with FlexPowerControl (down to 108 nA Standby mode and 62 uA/MHz run mode)

  • Core: ARM® 32-bit Cortex® -M33 CPU with TrustZone® and FPU.

  • Performance benchmark:

    • 1.5 DMPIS/MHz (Drystone 2.1)

    • 442 CoreMark® (4.02 CoreMark® /MHZ)

  • Security

    • Arm® TrustZone® and securable I/Os memories and peripherals

    • Flexible life cycle scheme with RDP (readout protection)

    • Root of trust thanks to unique boot entry and hide protection area (HDP)

    • Secure Firmware Installation thanks to embedded Root Secure Services

    • Secure Firmware Update support with TF-M

    • HASH hardware accelerator

    • Active tamper and protection temperature, voltage and frequency attacks

    • True Random Number Generator NIST SP800-90B compliant

    • 96-bit unique ID

    • 512-byte One-Time Programmable for user data

  • Clock management:

    • 4 to 48 MHz crystal oscillator

    • 32 kHz crystal oscillator for RTC (LSE)

    • Internal 16 MHz factory-trimmed RC ( ±1%)

    • Internal low-power 32 kHz RC ( ±5%)

    • Internal multispeed 100 kHz to 48 MHz oscillator, auto-trimmed by LSE (better than ±0.25 % accuracy)

    • 3 PLLs for system clock, USB, audio, ADC

  • Power management

    • Embedded regulator (LDO) with three configurable range output to supply the digital circuitry

    • Embedded SMPS step-down converter

    • External SMPS support

  • RTC with HW calendar, alarms and calibration

  • Up to 114 fast I/Os, most 5 V-tolerant, up to 14 I/Os with independent supply down to 1.08 V

  • Up to 22 capacitive sensing channels: support touchkey, linear and rotary touch sensors

  • Up to 16 timers and 2 watchdogs

    • 2x 16-bit advanced motor-control

    • 2x 32-bit and 5x 16-bit general purpose

    • 2x 16-bit basic

    • 3x low-power 16-bit timers (available in Stop mode)

    • 2x watchdogs

    • 2x SysTick timer

  • Memories

    • Up to 512 MB Flash, 2 banks read-while-write

    • 512 KB of SRAM including 64 KB with hardware parity check

    • External memory interface for static memories supporting SRAM, PSRAM, NOR, NAND and FRAM memories

    • OCTOSPI memory interface

  • Rich analog peripherals (independent supply)

    • 3x 12-bit ADC 5 MSPS, up to 16-bit with hardware oversampling, 200 uA/MSPS

    • 2x 12-bit DAC, low-power sample and hold

    • 2x operational amplifiers with built-in PGA

    • 2x ultra-low-power comparators

    • 4x digital filters for sigma delta modulator

  • 19x communication interfaces

    • USB Type-C / USB power delivery controller

    • 2.0 full-speed crystal less solution, LPM and BCD

    • 2x SAIs (serial audio interface)

    • 4x I2C FM+(1 Mbit/s), SMBus/PMBus

    • 6x USARTs (ISO 7816, LIN, IrDA, modem)

    • 3x SPIs (7x SPIs with USART and OCTOSPI in SPI mode)

    • 1xFDCAN

    • 1xSDMMC interface

    • 2x 14 channel DMA controllers

  • CRC calculation unit

  • Development support: serial wire debug (SWD), JTAG, Embedded Trace Macrocell™

More information about STM32L552ZE can be found here:

Supported Features

The Zephyr nucleo_l552ze_q board configuration supports the following hardware features:






ADC Controller



reset and clock control



DAC Controller



Direct Memory Access









nested vector interrupt controller












Trusted Firmware-M



serial port-polling; serial port-interrupt



die temperature sensor

The default configuration can be found in the defconfig and dts files:

Zephyr board options

The STM32L552e is an SoC with Cortex-M33 architecture. Zephyr provides support for building for both Secure and Non-Secure firmware.

The BOARD options are summarized below:




For building Trust Zone Disabled firmware


For building Non-Secure firmware

Here are the instructions to build Zephyr with a non-secure configuration, using tfm_ipc_ sample:

$ west build -b nucleo_l552ze_q/stm32l552xx/ns samples/tfm_integration/tfm_ipc/

Once done, before flashing, you need to first run a generated script that will set platform option bytes config and erase platform (among others, option bit TZEN will be set).

$ ./build/tfm/api_ns/
$ west flash

Please note that, after having run a TFM sample on the board, you will need to run ./build/tfm/api_ns/ once more to clean up the board from secure options and get back the platform back to a “normal” state and be able to run usual, non-TFM, binaries. Also note that, even then, TZEN will remain set, and you will need to use STM32CubeProgrammer to disable it fully, if required.

Connections and IOs

Nucleo L552ZE Q Board has 8 GPIO controllers. These controllers are responsible for pin muxing, input/output, pull-up, etc.

Available pins:

Nucleo L552ZE Q Zio left connector Nucleo L552ZE Q Zio right connector

For more details please refer to STM32 Nucleo-144 board User Manual.

Default Zephyr Peripheral Mapping:

  • UART_1_TX : PA9

  • UART_1_RX : PA10

  • UART_2_TX : PA2

  • UART_2_RX : PA3

  • UART_3_TX : PD8

  • UART_3_RX : PD9

  • I2C_1_SCL : PB6

  • I2C_1_SDA : PB7

  • SPI_1_NSS : PA4

  • SPI_1_SCK : PA5

  • SPI_1_MISO : PA6

  • SPI_1_MOSI : PA7

  • SPI_2_NSS : PB12

  • SPI_2_SCK : PB13

  • SPI_2_MISO : PB14

  • SPI_2_MOSI : PB15

  • SPI_3_NSS : PB12

  • SPI_3_SCK : PC10

  • SPI_3_MISO : PC11

  • SPI_3_MOSI : PC12

  • PWM_2_CH1 : PA0

  • USER_PB : PC13

  • LD2 : PB7

  • DAC1 : PA4

  • ADC1 : PC0

System Clock

Nucleo L552ZE Q System Clock could be driven by internal or external oscillator, as well as main PLL clock. By default System clock is driven by PLL clock at 110MHz, driven by 4MHz medium speed internal oscillator.

Serial Port

Nucleo L552ZE Q board has 6 U(S)ARTs. The Zephyr console output is assigned to UART2. Default settings are 115200 8N1.

Programming and Debugging

Applications for the nucleo_l552ze_q board configuration can be built and flashed in the usual way (see Building an Application and Run an Application for more details).


Nucleo L552ZE Q board includes an ST-LINK/V2-1 embedded debug tool interface. Support can be enabled on pyocd by adding “pack” support with the following pyocd command:

$ pyocd pack --update
$ pyocd pack --install stm32l552ze

Alternatively, this interface is supported by the openocd version included in the Zephyr SDK since v0.13.1.

Flashing an application to Nucleo L552ZE Q

Connect the Nucleo L552ZE Q to your host computer using the USB port. Then build and flash an application. Here is an example for the Hello World application.

Run a serial host program to connect with your Nucleo board:

$ minicom -D /dev/ttyACM0

Then build and flash the application.

# From the root of the zephyr repository
west build -b nucleo_l552ze_q samples/hello_world
west flash

You should see the following message on the console:

Hello World! arm


You can debug an application in the usual way. Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b nucleo_l552ze_q samples/hello_world
west debug