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 WBA55CG


NUCLEO-WBA55CG is a Bluetooth® Low Energy wireless and ultra-low-power board embedding a powerful and ultra-low-power radio compliant with the Bluetooth® Low Energy SIG specification v5.3.

The ARDUINO® Uno V3 connectivity support and the ST morpho headers allow the easy expansion of the functionality of the STM32 Nucleo open development platform with a wide choice of specialized shields.

  • Ultra-low-power wireless STM32WBA55CG microcontroller based on the Arm® Cortex®‑M33 core, featuring 1 Mbyte of flash memory and 128 Kbytes of SRAM in a UFQFPN48 package

  • MCU RF board (MB1863):

    • 2.4 GHz RF transceiver supporting Bluetooth® specification v5.3

    • Arm® Cortex® M33 CPU with TrustZone®, MPU, DSP, and FPU

    • Integrated PCB antenna

  • Three user LEDs

  • Three user and one reset push-buttons

  • Board connectors:

    • USB Micro-B

    • ARDUINO® Uno V3 expansion connector

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

  • Flexible power-supply options: ST-LINK USB VBUS or external sources

  • On-board STLINK-V3MODS debugger/programmer with USB re-enumeration capability: mass storage, Virtual COM port, and debug port

Nucleo WBA55CG


The STM32WBA55xx multiprotocol wireless and ultralow power devices embed a powerful and ultralow power radio compliant with the Bluetooth® SIG Low Energy specification 5.3. They contain a high-performance Arm Cortex-M33 32-bit RISC core. They operate at a frequency of up to 100 MHz.

  • Includes ST state-of-the-art patented technology

  • Ultra low power radio:

    • 2.4 GHz radio

    • RF transceiver supporting Bluetooth® Low Energy 5.3 specification

    • Proprietary protocols

    • RX sensitivity: -96 dBm (Bluetooth® Low Energy at 1 Mbps)

    • Programmable output power, up to +10 dBm with 1 dB steps

    • Integrated balun to reduce BOM

    • Suitable for systems requiring compliance with radio frequency regulations ETSI EN 300 328, EN 300 440, FCC CFR47 Part 15 and ARIB STD-T66

  • Ultra low power platform with FlexPowerControl:

    • 1.71 to 3.6 V power supply

      • 40 °C to 85 °C temperature range

    • Autonomous peripherals with DMA, functional down to Stop 1 mode

    • 140 nA Standby mode (16 wake-up pins)

    • 200 nA Standby mode with RTC

    • 2.4 µA Standby mode with 64 KB SRAM

    • 16.3 µA Stop mode with 64 KB SRAM

    • 45 µA/MHz Run mode at 3.3 V

    • Radio: Rx 7.4 mA / Tx at 0 dBm 10.6 mA

  • Core: Arm® 32-bit Cortex®-M33 CPU with TrustZone®, MPU, DSP, and FPU

  • ART Accelerator™: 8-Kbyte instruction cache allowing 0-wait-state execution from flash memory (frequency up to 100 MHz, 150 DMIPS)

  • Power management: embedded regulator LDO supporting voltage scaling

  • Benchmarks:

    • 1.5 DMIPS/MHz (Drystone 2.1)

    • 407 CoreMark® (4.07 CoreMark/MHz)

  • Clock sources:

    • 32 MHz crystal oscillator

    • 32 kHz crystal oscillator (LSE)

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

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

    • PLL for system clock and ADC

  • Memories:

    • 1 MB flash memory with ECC, including 256 Kbytes with 100 cycles

    • 128 KB SRAM, including 64 KB with parity check

    • 512-byte (32 rows) OTP

  • Rich analog peripherals (independent supply):

    • 12-bit ADC 2.5 Msps with hardware oversampling

  • Communication peripherals:

    • Three UARTs (ISO 7816, IrDA, modem)

    • Two SPIs

    • Two I2C Fm+ (1 Mbit/s), SMBus/PMBus®

  • System peripherals:

    • Touch sensing controller, up to 20 sensors, supporting touch key, linear,

      rotary touch sensors

    • One 16-bit, advanced motor control timer

    • Three 16-bit timers

    • One 32-bit timer

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

    • Two Systick timers

    • Two watchdogs

    • 8-channel DMA controller, functional in Stop mode

  • Security and cryptography:

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

    • Flexible life cycle scheme with RDP and password protected debug

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

    • SFI (secure firmware installation) thanks to embedded RSS (root secure services)

    • Secure data storage with root hardware unique key (RHUK)

    • Secure firmware upgrade support with TF-M

    • Two AES co-processors, including one with DPA resistance

    • Public key accelerator, DPA resistant

    • HASH hardware accelerator

    • True random number generator, NIST SP800-90B compliant

    • 96-bit unique ID

    • Active tampers

    • CRC calculation unit

  • Up to 35 I/Os (most of them 5 V-tolerant) with interrupt capability

  • Development support:

    • Serial wire debug (SWD), JTAG

  • ECOPACK2 compliant package

More information about STM32WBA series can be found here:

Supported Features

The Zephyr nucleo_wba55cg board configuration supports the following hardware features:






nested vector interrupt controller



serial port-polling; serial port-interrupt


















independent watchdog



True Random number generator



Bluetooth Low Energy




Other hardware features are not yet supported on this Zephyr port.

The default configuration can be found in the defconfig file: boards/st/nucleo_wba55cg/nucleo_wba55cg_defconfig

Bluetooh support

BLE support is enabled on nucleo_wba55cg. To build a zephyr sample using this board you first need to install Bluetooth Controller libraries available in Zephyr as binary blobs.

To fetch Binary Blobs:

west blobs fetch stm32

Connections and IOs

Nucleo WBA55CG Board has 4 GPIO controllers. These controllers are responsible for pin muxing, input/output, pull-up, etc.

Default Zephyr Peripheral Mapping:

  • USART_1 TX/RX : PB12/PA8

  • I2C_1_SCL : PB2

  • I2C_1_SDA : PB1

  • USER_PB : PC13

  • LD1 : PB4

  • SPI_1_NSS : PA12 (arduino_spi)

  • SPI_1_SCK : PB4 (arduino_spi)

  • SPI_1_MISO : PB3 (arduino_spi)

  • SPI_1_MOSI : PA15 (arduino_spi)

System Clock

Nucleo WBA55CG System Clock could be driven by internal or external oscillator, as well as main PLL clock. By default System clock is driven by HSE+PLL clock at 100MHz.

Serial Port

Nucleo WBA55CG board has 1 U(S)ARTs. The Zephyr console output is assigned to USART1. Default settings are 115500 8N1.

Programming and Debugging

Nucleo WBA55CG board includes an ST-LINK/V3 embedded debug tool interface. It could be used for flash and debug using either OpenOCD or STM32Cube ecosystem tools.


STM32CubeProgrammer is configured as flashing tool by default. If available, OpenOCD could be used. Same process applies with both tools.

Flashing an application to Nucleo WBA55CG

Here is an example for the Blinky application.

# From the root of the zephyr repository
west build -b nucleo_wba55cg samples/basic/blinky
west flash

You will see the LED blinking every second.


Debugging using OpenOCD

You can debug an application in the usual way using OpenOCD. Here is an example for the Blinky application.

# From the root of the zephyr repository
west build -b nucleo_wba55cg samples/basic/blinky
west debug

Debugging using STM32CubeIDE

You can debug an application using a STM32WBA compatible version of STM32CubeIDE.

For that:

  • Create an empty STM32WBA project by going to File > New > STM32 project

  • Select your MCU, click Next, and select an Empty project.

  • Right click on your project name, select Debug as > Debug configurations

  • In the new window, create a new target in STM32 Cortex-M C/C++ Application

  • Select the new target and enter the path to zephyr.elf file in the C/C++ Application field

  • Check Disable auto build

  • Run debug