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 menu on the left and select the desired version.



The STM32WB5MM-DK Discovery kit is designed as a complete demonstration and development platform for the STMicroelectronics STM32W5MMG module based on the Arm® Cortex®-M4 and Arm® Cortex®-M0+ cores. The STM32 device is a multi-protocol wireless and ultra-low-power device embedding a powerful and ultra-low-power radio compliant with the Bluetooth® Low Energy (BLE) SIG specification v5.2 and with IEEE 802.15.4-2011.

STM32WB5MM-DK supports the following features:

  • STM32WB5MMG (1-Mbyte Flash memory, 256-Kbyte SRAM)
    • Dual-core 32‑bit (Arm® Cortex®-M4 and M0+)

    • 2.4 GHz RF transceiver

    • 0.96-inch 128x64 OLED display

    • 128-Mbit Quad-SPI NOR Flash Memory

    • Temperature sensor

    • Accelerometer/gyroscope sensor

    • Time-of-Flight and gesture-detection sensor

    • Digital microphone

    • RGB LED

    • Infrared LED

    • 3 push-buttons (2 users and 1 reset) and 1 touch key button

  • Board connectors:
    • STMod+

    • ARDUINO® Uno V3 expansion connector

    • USB user with Micro-B connector

    • TAG10 10-pin footprint

  • Flexible power-supply options:
    • ST-LINK/V2-1 USB connector,

    • 5 V delivered by:
      • ARDUINO®,

      • external connector,

      • USB charger, or USB power

  • On-board ST-LINK/V2-1 debugger/programmer with USB re-enumeration
    • Virtual COM port and debug port


More information about the board can be found in STM32WB5MM-DK on


STM32WB5MMG is an ultra-low-power and small form factor certified 2.4 GHz wireless module. It supports Bluetooth® Low Energy 5.4, Zigbee® 3.0, OpenThread, dynamic, and static concurrent modes, and 802.15.4 proprietary protocols.

Based on the STMicroelectronics STM32WB55VGY wireless microcontroller, STM32WB5MMG provides best-in-class RF performance thanks to its high receiver sensitivity and output power signal. Its low-power features enable extended battery life, small coin-cell batteries, and energy harvesting.

  • Ultra-low-power with FlexPowerControl

  • Core: ARM® 32-bit Cortex®-M4 CPU with FPU

  • Radio:

    • 2.4GHz

    • RF transceiver supporting:

      • Bluetooth® 5.4 specification,

      • IEEE 802.15.4-2011 PHY and MAC,

      • Zigbee® 3.0

    • RX sensitivity:

      • -96 dBm (Bluetooth® Low Energy at 1 Mbps),

      • -100 dBm (802.15.4)

    • Programmable output power up to +6 dBm with 1 dB steps

    • Integrated balun to reduce BOM

    • Support for 2 Mbps

    • Support GATT caching

    • Support EATT (enhanced ATT)

    • Support advertising extension

    • Accurate RSSI to enable power control

  • Clock Sources:

    • 32 MHz crystal oscillator with integrated trimming capacitors (Radio and CPU clock)

    • 32 kHz crystal oscillator for RTC (LSE)

    • Internal low-power 32 kHz (±5%) RC (LSI1)

    • Internal low-power 32 kHz (stability ±500 ppm) RC (LSI2)

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

    • High speed internal 16 MHz factory trimmed RC (±1%)

    • 2x PLL for system clock, USB, SAI, ADC

More information about STM32WB55RG can be found here:

Supported Features

The Zephyr STM32WB5MM-DK board configuration supports the following hardware features:






serial port-polling; serial port-interrupt

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

The default configuration can be found in the defconfig file: boards/st/stm32wb5mm_dk/stm32wb5mm_dk_defconfig

Bluetooth and compatibility with STM32WB Copro Wireless Binaries

To operate bluetooth on STM32WB5MMG, Cortex-M0 core should be flashed with a valid STM32WB Coprocessor binaries (either ‘Full stack’ or ‘HCI Layer’). These binaries are delivered in STM32WB Cube packages, under Projects/STM32WB_Copro_Wireless_Binaries/STM32WB5x/.

For compatibility information with the various versions of these binaries, please check modules/hal/stm32/lib/stm32wb/hci/README in the hal_stm32 repo.

Note that since STM32WB Cube package V1.13.2, “full stack” binaries are not compatible anymore for a use in Zephyr and only “HCI Only” versions should be used on the M0 side.

Connections and IOs

Default Zephyr Peripheral Mapping:

  • UART_1 TX/RX : PB7/PB6 ( Connected to ST-Link VCP)

  • LPUART_1 TX/RX : PA3/PA2

  • USB : PA11/PA12

  • SWD : PA13/PA14

System Clock

STM32WB5MMG System Clock could be driven by internal or external oscillator, as well as main PLL clock. By default System clock is driven by HSE clock at 32MHz.

Serial Port

STM32WB5MM-DK board has 2 (LP)U(S)ARTs. The Zephyr console output is assigned to USART1. Default settings are 115200 8N1.

Programming and Debugging

Applications for the stm32wb5mm_dk board configuration can be built the usual way (see Building an Application).


STM32WB5MM-DK has an on-board ST-Link to flash and debug the firmware on the module.

Flashing hello_world application to STM32WB5MM-DK

Connect the STM32WB5MM-DK to your host computer using the USB port (CN11). Then build and flash an application. Here is an example for the hello_world application.

Run a serial host program to connect with your STM32WB5MM-DK board:

$ minicom -D /dev/ttyACM0

Then first build and flash the application for the STM32WB5MM-DK board.

# From the root of the zephyr repository
west build -b stm32wb5mm_dk samples/hello_world
west flash

Reset the board and you should see the following messages on the console:

Hello World! stm32w5mm_dk


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 stm32wb5mm_dk samples/hello_world
west debug