nRF52 Adafruit Feather

Overview

Zephyr applications use the nrf52_adafruit_feather board configuration to run on the nRF52 Adafruit Bluefruit Feather hardware. It provides support for the Nordic Semiconductor nRF52832 ARM Cortex-M4F CPU and the following devices:

  • NVIC
  • RTC
  • UART
  • GPIO
  • FLASH
  • RADIO (Bluetooth Low Energy)
  • Segger RTT (RTT Console)
nRF52 Adafruit Feather Board

nRF52 Adafruit Feather Board (Credit: Adafruit)

More information about the board and its features can be found at the Adafruit Feather nRF52 Bluefruit Learning Guide [1]. The Nordic Semiconductor Documentation library [4] contains the processor’s information and the datasheet.

Hardware

  • nRF52832 ARM Cortex-M4F processor at 64 MHz
  • 32.768 kHz crystal oscillator
  • 512 KiB flash memory and 64 KiB of SRAM
  • Battery connector and charger for 3.7 V lithium polymer batteries
  • Charging indicator LED
  • 2 User LEDs
  • Reset button
  • SWD connector
  • USB serial converter

Supported Features

The nRF52 Adafruit Feather board configuration supports the following hardware features:

Interface Controller Driver/Component
NVIC on-chip nested vectored interrupt controller
RTC on-chip system clock
UART on-chip serial port
GPIO on-chip gpio
FLASH on-chip flash
RADIO on-chip Bluetooth
RTT on-chip console

Other hardware features are not supported by the Zephyr kernel.

Connections and IOs

The Adafruit Feather nRF52 Bluefruit Learning Guide [1] has detailed information about the board including pinouts [3] and the schematic [2].

LED

  • LED0 (red) = P0.17
  • LED1 (blue) = P0.19

Push buttons

  • DFU = SW0 = P0.20
  • RESET = SW1 = P0.21/reset

Programming and Debugging

The nrf52_adafruit_feather board is available in two different versions:

Applications for the nrf52_adafruit_feather board configuration can be built and flashed in the usual way (see Build an Application and Run an Application for more details); however, the standard debugging targets are not currently available.

Flashing

Flashing Zephyr onto the nrf52_adafruit_feather board requires an external J-Link programmer. The programmer is attached to the X1 SWD header.

Follow the instructions in the Nordic nRF5x Segger J-Link page to install and configure all the necessary software. Further information can be found in Flashing. Then build and flash applications as usual (see Build an Application and Run an Application for more details).

Here is an example for the Hello World application.

  1. Build the Zephyr kernel and the Hello World sample application:

    # On Linux/macOS
    cd $ZEPHYR_BASE/samples/hello_world
    mkdir build && cd build
    # On Windows
    cd %ZEPHYR_BASE%\samples\hello_world
    mkdir build & cd build
    cmake -GNinja -DBOARD=nrf52_adafruit_feather ..
    ninja
    
  2. Connect the Adafruit nRF52 Feather to your host computer using USB

  3. Run your favorite terminal program to listen for output.

    $ minicom -D <tty_device> -b 115200
    

    Replace <tty_device> with the port where the nRF52 Adafruit Feather board can be found. For example, under Linux, /dev/ttyUSB0.

  4. Flash the image:

    # On Linux/macOS
    cd $ZEPHYR_BASE/samples/hello_world
    mkdir build && cd build
    # On Windows
    cd %ZEPHYR_BASE%\samples\hello_world
    mkdir build & cd build
    cmake -GNinja -DBOARD=nrf52_adafruit_feather ..
    ninja flash
    

    You should see “Hello World! arm” in your terminal.

Debugging

The nrf52_adafruit_feather board does not have an on-board J-Link debug IC as some nRF5x development boards, however, instructions from the Nordic nRF5x Segger J-Link page also apply to this board, with the additional step of connecting an external debugger.

Testing the LEDs and buttons on the nRF52 Adafruit Feather

There are several samples that allow you to test that the buttons (switches) and LEDs on the board are working properly with Zephyr:

You can build and flash the examples to make sure Zephyr is running correctly on your board. The button and LED definitions can be found in boards/arm/nrf52_adafruit_feather/board.h.