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Adafruit Feather nRF52840 Express

Support for the Adafruit Feather nRF52840 Express. More...

Detailed Description

Support for the Adafruit Feather nRF52840 Express.

General information

The Feather nRF52840 Express is a development board from Adafruits Feather board family. It provides native USB support, Bluetooth Low Energy and IEEE 802.15.4 support via the nRF52840 MCU.

top-down view on feather-nrf52840

Flash the board

The board is flashed using its on-board UF2 boot loader by default. The boot loader will present a mass storage device that has to be mounted to /media/MDK-DONGLE so uf2conv.py can find it. If you have an auto-mounter installed this will happen automatically.

The rest of the process is automated in the usual way with BOARD=feather-nrf52840.

Example with hello-world application:

make BOARD=feather-nrf52840 -C examples/hello-world flash term

If RIOT is already running on the board, it will automatically reset the CPU and enter the bootloader. If some other firmware is running or RIOT crashed, you need to enter the bootloader manually by double-tapping the board's reset button while the device is connected.

Otherwise see the Flashing section in nRF52 common. The easiest way is to use an external Segger J-Link Programmer connected to the SWD Connector.

Flashing the uf2 bootloader

To flash the uf2 bootloader (if it is no longer present on your BOARD), you need to have nrfjprog installed, connect a jlink to your BOARD and execute the following commands:

git clone git@github.com:adafruit/Adafruit_nRF52_Bootloader.git
cd Adafruit_nRF52_Bootloader
# only download what is needed, use
# `git submodule update --init --recursive`
# to download everything
git submodule update --init
git -C lib/tinyusb submodule update --init hw/mcu/nordic/nrfx/
pip3 install --user adafruit-nrfutil
make BOARD=feather_nrf52840_express all
make BOARD=feather_nrf52840_express flash


To connect a terminal to the Feather, RIOT chooses stdio_cdc_acm per default. This lets you access the Feather directly over USB.

You have several alternative possibilities to connect to the board.

  1. With
    USEMODULE += stdio_uart
    and an FTDI adapter connected to the Feather's RX and TX ports you can use UART-based terminals to connect to the feather
  2. With
    USEMODULE += stdio_rtt
    you can use the Segger J-Link Programmer as a serial interface to the device.


file  board.h
 Board specific configuration for the Adafruit Feather nRF52840 Express.
file  gpio_params.h
 Configuration of SAUL mapped GPIO pins.
file  periph_conf.h
 Peripheral configuration for the Adafruit Feather nRF52840 Express.