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 G431RB


The Nucleo G431RB board features an ARM Cortex-M4 based STM32G431RB MCU with a wide range of connectivity support and configurations. Here are some highlights of the Nucleo G431RB board:

  • STM32 microcontroller in LQFP64 package

  • Arduino Uno V3 connectivity

  • On-board ST-LINK/V3E debugger/programmer with SWD connector

  • Flexible board power supply:

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

    • Power management access point

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

  • Two push-buttons: RESET and USER

Nucleo G431RB

More information about the board can be found at the Nucleo G431RB website.


The STM32G431RB SoC provides the following hardware IPs:

  • Ultra-low-power with FlexPowerControl (down to 28 nA Standby mode and 84 µA/MHz run mode)

  • Core: ARM® 32-bit Cortex® -M4 CPU with FPU, frequency up to 170 MHz

  • Clock Sources:

    • 4 to 48 MHz crystal oscillator (HSE)

    • 32 kHz crystal oscillator for RTC (LSE)

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

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

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

  • RTC with HW calendar, alarms and calibration

  • 14x timers:

    • 1x 32-bit timer and 2x 16-bit timers with up to four IC/OC/PWM or pulse counter and quadrature (incremental) encoder input

    • 2x 16-bit 8-channel advanced motor control timers, with up to 8x PWM channels, dead time generation and emergency stop

    • 1x 16-bit timer with 2x IC/OCs, one OCN/PWM, dead time generation and emergency stop

    • 2x 16-bit timers with IC/OC/OCN/PWM, dead time generation and emergency stop

    • 2x watchdog timers (independent, window)

    • 2x 16-bit basic timers

    • SysTick timer

    • 1x low-power timer

  • Up to 86 fast I/Os, most 5 V-tolerant

  • Memories

    • Up to 128 KB single bank Flash, proprietary code readout protection

    • Up to 22 KB of SRAM including 16 KB with hardware parity check

  • Rich analog peripherals (independent supply)

    • 2x 12-bit ADC 5 MSPS, up to 16-bit with hardware oversampling, 200 µA/MSPS

    • 4x 12-bit DAC, low-power sample and hold

    • 3x operational amplifiers with built-in PGA

    • 4x ultra-fast rail-to-rail analog comparators

  • 16x communication interfaces

    • 1 x FDCAN controller supporting flexible data rate

    • 3x I2C FM+(1 Mbit/s), SMBus/PMBus

    • 4x USARTs (ISO 7816, LIN, IrDA, modem)

    • 1x LPUART

    • 3x SPIs (2x with multiplexed half duplex I2S interface)

    • 1x SAI (serial audio interface)

    • USB 2.0 full-speed interface with LPM and BCD support

    • IRTIM (Infrared interface)

    • USB Type-C™ /USB power delivery controller (UCPD)

  • 12-channel DMA controller

  • True random number generator (RNG)

  • CRC calculation unit, 96-bit unique ID

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

More information about STM32G431RB can be found here:

Supported Features

The Zephyr nucleo_g431rb board configuration supports the following hardware features:






nested vector interrupt controller



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/nucleo_g431rb/nucleo_g431rb_defconfig

Connections and IOs

Nucleo G431RB Board has 6 GPIO controllers. These controllers are responsible for pin muxing, input/output, pull-up, etc.

For more details please refer to STM32G4 Nucleo-64 board User Manual.

Default Zephyr Peripheral Mapping:

  • UART_1_TX : PC4

  • UART_1_RX : PC5

  • LPUART_1_TX : PA2

  • LPUART_1_RX : PA3

  • I2C_1_SCL : PB8

  • I2C_1_SDA : PB9

  • SPI_1_NSS : PB6

  • 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 : PA15

  • SPI_3_SCK : PC10

  • SPI_3_MISO : PC11

  • SPI_3_MOSI : PC12

  • PWM_3_CH1 : PB4

  • USER_PB : PC13

  • LD2 : PA5

  • DAC1_OUT1 : PA4

System Clock

Nucleo G431RB 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 150MHz, driven by 16MHz high speed internal oscillator. The clock can be boosted to 170MHz if boost mode is selected.

Serial Port

Nucleo G431RB board has 3 U(S)ARTs and one LPUART. The Zephyr console output is assigned to LPUART1. Default settings are 115200 8N1.

Please note that LPUART1 baudrate is limited to 9600 if the MCU is clocked by LSE (32.768 kHz) in low power mode.

Programming and Debugging

Applications for the nucleo_g431rb board configuration can be built and flashed in the usual way (see Building an Application and Run an Application for more details).


Nucleo G431RB board includes an ST-LINK/V3E embedded debug tool interface.

This interface is not yet supported by the openocd version included in the Zephyr SDK.

Instead, support can be enabled on pyocd by adding “pack” support with the following pyocd command:

$ pyocd pack --update
$ pyocd pack --install stm32g431rb

Note: To manually enable the openocd interface, You can still update, compile and install a ‘local’ openocd from the official openocd repo . Then run the following openocd command where the ‘/usr/local/bin/openocd’is your path for the freshly installed openocd, given by “$ which openocd” :

$ west flash --openocd /usr/local/bin/openocd

Flashing an application to Nucleo G431RB

Connect the Nucleo G431RB to your host computer using the USB port, then run a serial host program to connect with your Nucleo board.

$ minicom -D /dev/ttyACM0

Now build and flash an application. Here is an example for Hello World.

# From the root of the zephyr repository
west build -b nucleo_g431rb 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_g431rb samples/hello_world
west debug