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.

EFR32 BRD4170A (SLWRB4170A)


The EFR32MG12 Mighty Gecko Radio Board contains a Wireless System-On-Chip from the EFR32MG12 family built on an ARM Cortex®-M4F processor with excellent low power capabilities.

SLWRB4170A Mighty Gecko Radio Board

SLWRB4170A (image courtesy of Silicon Labs)

The BRD4170A a.k.a. SLWRB4170A radio board plugs into the Wireless Starter Kit Mainboard BRD4001A and is supported as one of EFR32 Radio Boards.


  • EFR32MG12P433F1024GM68 Mighty Gecko SoC

  • CPU core: ARM Cortex®-M4 with FPU

  • Flash memory: 1024 kB

  • RAM: 256 kB

  • Transmit power: up to +19 dBm

  • Operation frequency: 2.4 GHz and Sub-Ghz

  • Crystals for LFXO (32.768 kHz) and HFXO (38.4 MHz).

For more information about the EFR32MG12 SoC and BRD4170A board, refer to these documents:

Supported Features

Please refer to EFR32 Radio Board Supported Features for details of the configuration and common features supported by the efr32_radio/efr32mg12p433f1024gm68 board.

The default configuration can be found in boards/silabs/efr32_radio/efr32_radio_efr32mg12p433f1024gm68_defconfig

System Clock

The EFR32MG12P SoC is configured to use the 38.4 MHz external oscillator on the board.

Serial Port

The EFR32MG12P SoC has four USARTs and one Low Energy UARTs (LEUART). USART0 is connected to the board controller and is used for the console.

Programming and Debugging

Please refer to Programming and Debugging EFR32 Radio Board for details on the supported debug interfaces.


Connect the BRD4001A board with a mounted BRD4170A radio module to your host computer using the USB port.

Here is an example for the Hello World application.

# From the root of the zephyr repository
west build -b efr32_radio/efr32mg12p433f1024gm68 samples/hello_world
west flash

Open a serial terminal (minicom, putty, etc.) with the following settings:

  • Speed: 115200

  • Data: 8 bits

  • Parity: None

  • Stop bits: 1

Reset the board and you should see the following message in the terminal:

Hello World! efr32_radio