Adafruit Feather nRF52840 (Express, Sense)

Overview

The Adafruit Feather nRF52840 provides support for the Nordic Semiconductor nRF52840 ARM Cortex-M4F CPU and the following devices:

  • ADC

  • CLOCK

  • FLASH

  • GPIO

  • I2C

  • MPU

  • NVIC

  • PWM

  • RADIO (Bluetooth Low Energy and 802.15.4)

  • RTC

  • Segger RTT (RTT Console)

  • SPI

  • UART

  • USB

  • WDT

Adafruit Feather nRF52840 Express

Hardware

  • nRF52840 ARM Cortex-M4F processor at 64 MHz

  • 1 MB flash memory and 256 KB of SRAM

  • Battery connector and charger for 3.7 V lithium polymer batteries

  • Charging indicator LED

  • 2 User LEDs

  • 1 NeoPixel LED

  • Reset button

  • SWD connector (Express only)

  • SWD solder pads on bottom of PCB (Sense only)

  • LSM6DS33 Accel/Gyro (Sense only)

  • LIS3MDL magnetometer (Sense only)

  • APDS9960 Proximity, Light, Color, and Gesture Sensor (Sense only)

  • MP34DT01-M PDM Microphone sound sensor (Sense only)

  • SHT3X Humidity sensor (Sense only)

  • BMP280 temperature and barometric pressure/altitude (Sense only)

Supported Features

The Adafruit Feather nRF52840 board configuration supports the following hardware features:

Interface

Controller

Driver/Component

ADC

on-chip

adc

CLOCK

on-chip

clock_control

FLASH

on-chip

flash

GPIO

on-chip

gpio

I2C

on-chip

i2c

MPU

on-chip

arch/arm

NVIC

on-chip

arch/arm

PWM

on-chip

pwm

RADIO

on-chip

Bluetooth, ieee802154

RTC

on-chip

system clock

SPI

on-chip

spi

UART

on-chip

serial

USB

on-chip

usb

WDT

on-chip

watchdog

Other hardware features have not been enabled yet for this board.

Connections and IOs

The Adafruit Feather nRF52840 Express Learn site [1] has detailed information about the board including pinouts (Express) [2] and the schematic (Express) [3].

LED

  • LED0 (red) = P1.15 (Express)

  • LED0 (red) = P1.9 (Sense)

  • LED1 (blue) = P1.10

Push buttons

  • SWITCH = P1.02

  • RESET = P0.18

Programming and Debugging

Flashing

Flashing Zephyr onto both the Feather nRF52840 Express and Sense is possible using the SWD headers. Only the Express board has an SWD connector however.

Both the Feather nRF52840 Express and Sense ship with the Adafruit nRF52 Bootloader [7] which supports flashing using UF2 [8]. This allows easy flashing of new images, but does not support debugging the device.

  1. Build the Zephyr kernel and the Blinky sample application.

west build -b adafruit_feather_nrf52840 samples/basic/blinky

  1. If using UF2, connect the board to your host computer using USB.

  2. Tap the reset button twice quickly to enter bootloader mode. A mass storage device named FTHR840BOOT for (Express) or FTHRSNSBOOT (Sense) should appear on the host. Ensure this is mounted.

  3. Flash the image.

west build -b adafruit_feather_nrf52840 samples/basic/blinky
west flash

  1. You should see the red LED blink.

References