Feather nRF52840 (Express, Sense)

Board Overview

Feather nRF52840 (Express, Sense)

Name:

adafruit_feather_nrf52840

Vendor:

Adafruit Industries, LLC

Architecture:

arm

SoC:

nrf52840

Browse board sources

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

ExpressSense

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 supports the hardware features listed below.

on-chip / on-board

Feature integrated in the SoC / present on the board.

2 / 2

Number of instances that are enabled / disabled.
Click on the label to see the first instance of this feature in the board/SoC DTS files.

vnd,foo

Compatible string for the Devicetree binding matching the feature.
Click on the link to view the binding documentation.

adafruit_feather_nrf52840

/

nrf52840nrf52840/sensenrf52840/sense/uf2nrf52840/uf2

adafruit_feather_nrf52840/nrf52840 target

Type	Location	Description	Compatible
CPU	on-chip	ARM Cortex-M4F CPU1	arm,cortex-m4f
ADC	on-chip	Nordic Semiconductor nRF family SAADC node1	nordic,nrf-saadc
ARM architecture	on-chip	Nordic UICR (User Information Configuration Registers)1	nordic,nrf-uicr
	on-chip	Nordic EGU (Event Generator Unit)6	nordic,nrf-egu
	on-chip	Nordic nRF family ACL (Access Control List)1	nordic,nrf-acl
	on-chip	Nordic nRF family MWU (Memory Watch Unit)1	nordic,nrf-mwu
Audio	on-chip	Nordic PDM (Pulse Density Modulation interface)1	nordic,nrf-pdm
Clock control	on-chip	Nordic nRF clock control node1	nordic,nrf-clock
Comparator	on-chip	Nordic nRF COMP (analog COMParator)1	nordic,nrf-comp
Counter	on-chip	Nordic nRF timer node5	nordic,nrf-timer
Cryptographic accelerator	on-chip	Nordic ECB (AES electronic codebook mode encryption)1	nordic,nrf-ecb
	on-chip	Nordic nRF family CCM (AES CCM mode encryption)1	nordic,nrf-ccm
	on-chip	ARM TrustZone CryptoCell 3101	arm,cryptocell-310
Debug	on-chip	ARMv7 instrumentation trace macrocell1	arm,armv7m-itm
Flash controller	on-chip	Nordic NVMC (Non-Volatile Memory Controller)1	nordic,nrf52-flash-controller
	on-chip	Properties defining the interface for the Nordic QSPI peripheral1	nordic,nrf-qspi
GPIO & Headers	on-chip	NRF5 GPIOTE1	nordic,nrf-gpiote
	on-chip	NRF5 GPIO2	nordic,nrf-gpio
	on-board	GPIO pins exposed on Adafruit Feather headers1	adafruit-feather-header
I2C	on-chip	Nordic nRF family TWI (TWI master)1	nordic,nrf-twi
	on-chip	Nordic nRF family TWIM (TWI master with EasyDMA)1	nordic,nrf-twim
I2S	on-chip	Nordic I2S (Inter-IC sound interface)1	nordic,nrf-i2s
IEEE 802.15.4	on-chip	Nordic nRF IEEE 802.15.4 node1	nordic,nrf-ieee802154
IIO	on-board	Description for a voltage divider, with optional ability to measure resistance of the upper leg1	voltage-divider
Input	on-board	Group of GPIO-bound input keys1	gpio-keys
Interrupt controller	on-chip	ARMv7-M NVIC (Nested Vectored Interrupt Controller)1	arm,v7m-nvic
LED	on-board	Group of GPIO-controlled LEDs1	gpio-leds
Miscellaneous	on-chip	Nordic FICR (Factory Information Configuration Registers)1	nordic,nrf-ficr
	on-chip	Nordic nRF family PPI (Programmable Peripheral Interconnect)1	nordic,nrf-ppi
MTD	on-chip	Flash node1	soc-nv-flash
	on-chip	Fixed partitions of a flash (or other non-volatile storage) memory1	fixed-partitions
	on-board	QSPI NOR flash supporting the JEDEC CFI interface1	nordic,qspi-nor
Networking	on-chip	Nordic nRF family RADIO peripheral1	nordic,nrf-radio
	on-chip	Nordic nRF family NFCT (Near Field Communication Tag)1	nordic,nrf-nfct
Pin control	on-chip	The nRF pin controller is a singleton node responsible for controlling pin function selection and pin properties1	nordic,nrf-pinctrl
Power management	on-chip	Nordic nRF power control node1	nordic,nrf-power
PWM	on-chip	nRF PWM4	nordic,nrf-pwm
	on-chip	nRFx S/W PWM1	nordic,nrf-sw-pwm
Regulator	on-chip	Nordic nRF5X regulator (fixed stage of the core supply)1	nordic,nrf5x-regulator
	on-chip	Nordic nRF52X regulator (high voltage stage of the main supply)1	nordic,nrf52x-regulator-hv
Retained memory	on-chip	Nordic GPREGRET (General Purpose Register Retention) device2	nordic,nrf-gpregret
RNG	on-chip	Nordic nRF family RNG (Random Number Generator)1	nordic,nrf-rng
RTC	on-chip	Nordic nRF RTC (Real-Time Counter)3	nordic,nrf-rtc
Sensors	on-chip	Nordic nRF family TEMP node1	nordic,nrf-temp
	on-chip	Nordic nRF quadrature decoder (QDEC) node1	nordic,nrf-qdec
Serial controller	on-chip	Nordic nRF family UART1	nordic,nrf-uart
	on-chip	Nordic nRF family UARTE (UART with EasyDMA)1	nordic,nrf-uarte
SPI	on-chip	Nordic nRF family SPIM (SPI master with EasyDMA)3	nordic,nrf-spim
	on-chip	Nordic nRF family SPI (SPI master)1	nordic,nrf-spi
SRAM	on-chip	Generic on-chip SRAM description1	mmio-sram
Timer	on-chip	ARMv7-M System Tick1	arm,armv7m-systick
USB	on-chip	Nordic nRF52 USB device controller1	nordic,nrf-usbd
Watchdog	on-chip	Nordic nRF family WDT (Watchdog Timer)1	nordic,nrf-wdt

adafruit_feather_nrf52840/nrf52840/sense target

Type	Location	Description	Compatible
CPU	on-chip	ARM Cortex-M4F CPU1	arm,cortex-m4f
ADC	on-chip	Nordic Semiconductor nRF family SAADC node1	nordic,nrf-saadc
ARM architecture	on-chip	Nordic UICR (User Information Configuration Registers)1	nordic,nrf-uicr
	on-chip	Nordic EGU (Event Generator Unit)6	nordic,nrf-egu
	on-chip	Nordic nRF family ACL (Access Control List)1	nordic,nrf-acl
	on-chip	Nordic nRF family MWU (Memory Watch Unit)1	nordic,nrf-mwu
Audio	on-chip	Nordic PDM (Pulse Density Modulation interface)1	nordic,nrf-pdm
Clock control	on-chip	Nordic nRF clock control node1	nordic,nrf-clock
Comparator	on-chip	Nordic nRF COMP (analog COMParator)1	nordic,nrf-comp
Counter	on-chip	Nordic nRF timer node5	nordic,nrf-timer
Cryptographic accelerator	on-chip	Nordic ECB (AES electronic codebook mode encryption)1	nordic,nrf-ecb
	on-chip	Nordic nRF family CCM (AES CCM mode encryption)1	nordic,nrf-ccm
	on-chip	ARM TrustZone CryptoCell 3101	arm,cryptocell-310
Debug	on-chip	ARMv7 instrumentation trace macrocell1	arm,armv7m-itm
Flash controller	on-chip	Nordic NVMC (Non-Volatile Memory Controller)1	nordic,nrf52-flash-controller
	on-chip	Properties defining the interface for the Nordic QSPI peripheral1	nordic,nrf-qspi
GPIO & Headers	on-chip	NRF5 GPIOTE1	nordic,nrf-gpiote
	on-chip	NRF5 GPIO2	nordic,nrf-gpio
	on-board	GPIO pins exposed on Adafruit Feather headers1	adafruit-feather-header
I2C	on-chip	Nordic nRF family TWI (TWI master)1	nordic,nrf-twi
	on-chip	Nordic nRF family TWIM (TWI master with EasyDMA)1	nordic,nrf-twim
I2S	on-chip	Nordic I2S (Inter-IC sound interface)1	nordic,nrf-i2s
IEEE 802.15.4	on-chip	Nordic nRF IEEE 802.15.4 node1	nordic,nrf-ieee802154
IIO	on-board	Description for a voltage divider, with optional ability to measure resistance of the upper leg1	voltage-divider
Input	on-board	Group of GPIO-bound input keys1	gpio-keys
Interrupt controller	on-chip	ARMv7-M NVIC (Nested Vectored Interrupt Controller)1	arm,v7m-nvic
LED	on-board	Group of GPIO-controlled LEDs1	gpio-leds
Miscellaneous	on-chip	Nordic FICR (Factory Information Configuration Registers)1	nordic,nrf-ficr
	on-chip	Nordic nRF family PPI (Programmable Peripheral Interconnect)1	nordic,nrf-ppi
MTD	on-chip	Flash node1	soc-nv-flash
	on-chip	Fixed partitions of a flash (or other non-volatile storage) memory1	fixed-partitions
	on-board	QSPI NOR flash supporting the JEDEC CFI interface1	nordic,qspi-nor
Networking	on-chip	Nordic nRF family RADIO peripheral1	nordic,nrf-radio
	on-chip	Nordic nRF family NFCT (Near Field Communication Tag)1	nordic,nrf-nfct
Pin control	on-chip	The nRF pin controller is a singleton node responsible for controlling pin function selection and pin properties1	nordic,nrf-pinctrl
Power management	on-chip	Nordic nRF power control node1	nordic,nrf-power
PWM	on-chip	nRF PWM4	nordic,nrf-pwm
	on-chip	nRFx S/W PWM1	nordic,nrf-sw-pwm
Regulator	on-chip	Nordic nRF5X regulator (fixed stage of the core supply)1	nordic,nrf5x-regulator
	on-chip	Nordic nRF52X regulator (high voltage stage of the main supply)1	nordic,nrf52x-regulator-hv
Retained memory	on-chip	Nordic GPREGRET (General Purpose Register Retention) device2	nordic,nrf-gpregret
RNG	on-chip	Nordic nRF family RNG (Random Number Generator)1	nordic,nrf-rng
RTC	on-chip	Nordic nRF RTC (Real-Time Counter)3	nordic,nrf-rtc
Sensors	on-board	Sensirion Humidity SHT3x-DIS humidity and temperature sensor1	sensirion,sht3xd
	on-chip	Nordic nRF family TEMP node1	nordic,nrf-temp
	on-chip	Nordic nRF quadrature decoder (QDEC) node1	nordic,nrf-qdec
Serial controller	on-chip	Nordic nRF family UART1	nordic,nrf-uart
	on-chip	Nordic nRF family UARTE (UART with EasyDMA)1	nordic,nrf-uarte
SPI	on-chip	Nordic nRF family SPIM (SPI master with EasyDMA)3	nordic,nrf-spim
	on-chip	Nordic nRF family SPI (SPI master)1	nordic,nrf-spi
SRAM	on-chip	Generic on-chip SRAM description1	mmio-sram
Timer	on-chip	ARMv7-M System Tick1	arm,armv7m-systick
USB	on-chip	Nordic nRF52 USB device controller1	nordic,nrf-usbd
Watchdog	on-chip	Nordic nRF family WDT (Watchdog Timer)1	nordic,nrf-wdt

adafruit_feather_nrf52840/nrf52840/sense/uf2 target

Type	Location	Description	Compatible
CPU	on-chip	ARM Cortex-M4F CPU1	arm,cortex-m4f
ADC	on-chip	Nordic Semiconductor nRF family SAADC node1	nordic,nrf-saadc
ARM architecture	on-chip	Nordic UICR (User Information Configuration Registers)1	nordic,nrf-uicr
	on-chip	Nordic EGU (Event Generator Unit)6	nordic,nrf-egu
	on-chip	Nordic nRF family ACL (Access Control List)1	nordic,nrf-acl
	on-chip	Nordic nRF family MWU (Memory Watch Unit)1	nordic,nrf-mwu
Audio	on-chip	Nordic PDM (Pulse Density Modulation interface)1	nordic,nrf-pdm
Clock control	on-chip	Nordic nRF clock control node1	nordic,nrf-clock
Comparator	on-chip	Nordic nRF COMP (analog COMParator)1	nordic,nrf-comp
Counter	on-chip	Nordic nRF timer node5	nordic,nrf-timer
Cryptographic accelerator	on-chip	Nordic ECB (AES electronic codebook mode encryption)1	nordic,nrf-ecb
	on-chip	Nordic nRF family CCM (AES CCM mode encryption)1	nordic,nrf-ccm
	on-chip	ARM TrustZone CryptoCell 3101	arm,cryptocell-310
Debug	on-chip	ARMv7 instrumentation trace macrocell1	arm,armv7m-itm
Flash controller	on-chip	Nordic NVMC (Non-Volatile Memory Controller)1	nordic,nrf52-flash-controller
	on-chip	Properties defining the interface for the Nordic QSPI peripheral1	nordic,nrf-qspi
GPIO & Headers	on-chip	NRF5 GPIOTE1	nordic,nrf-gpiote
	on-chip	NRF5 GPIO2	nordic,nrf-gpio
	on-board	GPIO pins exposed on Adafruit Feather headers1	adafruit-feather-header
I2C	on-chip	Nordic nRF family TWI (TWI master)1	nordic,nrf-twi
	on-chip	Nordic nRF family TWIM (TWI master with EasyDMA)1	nordic,nrf-twim
I2S	on-chip	Nordic I2S (Inter-IC sound interface)1	nordic,nrf-i2s
IEEE 802.15.4	on-chip	Nordic nRF IEEE 802.15.4 node1	nordic,nrf-ieee802154
IIO	on-board	Description for a voltage divider, with optional ability to measure resistance of the upper leg1	voltage-divider
Input	on-board	Group of GPIO-bound input keys1	gpio-keys
Interrupt controller	on-chip	ARMv7-M NVIC (Nested Vectored Interrupt Controller)1	arm,v7m-nvic
LED	on-board	Group of GPIO-controlled LEDs1	gpio-leds
Miscellaneous	on-chip	Nordic FICR (Factory Information Configuration Registers)1	nordic,nrf-ficr
	on-chip	Nordic nRF family PPI (Programmable Peripheral Interconnect)1	nordic,nrf-ppi
MTD	on-chip	Flash node1	soc-nv-flash
	on-chip	Fixed partitions of a flash (or other non-volatile storage) memory1	fixed-partitions
	on-board	QSPI NOR flash supporting the JEDEC CFI interface1	nordic,qspi-nor
Networking	on-chip	Nordic nRF family RADIO peripheral1	nordic,nrf-radio
	on-chip	Nordic nRF family NFCT (Near Field Communication Tag)1	nordic,nrf-nfct
Pin control	on-chip	The nRF pin controller is a singleton node responsible for controlling pin function selection and pin properties1	nordic,nrf-pinctrl
Power management	on-chip	Nordic nRF power control node1	nordic,nrf-power
PWM	on-chip	nRF PWM4	nordic,nrf-pwm
	on-chip	nRFx S/W PWM1	nordic,nrf-sw-pwm
Regulator	on-chip	Nordic nRF5X regulator (fixed stage of the core supply)1	nordic,nrf5x-regulator
	on-chip	Nordic nRF52X regulator (high voltage stage of the main supply)1	nordic,nrf52x-regulator-hv
Retained memory	on-chip	Nordic GPREGRET (General Purpose Register Retention) device2	nordic,nrf-gpregret
RNG	on-chip	Nordic nRF family RNG (Random Number Generator)1	nordic,nrf-rng
RTC	on-chip	Nordic nRF RTC (Real-Time Counter)3	nordic,nrf-rtc
Sensors	on-board	Sensirion Humidity SHT3x-DIS humidity and temperature sensor1	sensirion,sht3xd
	on-chip	Nordic nRF family TEMP node1	nordic,nrf-temp
	on-chip	Nordic nRF quadrature decoder (QDEC) node1	nordic,nrf-qdec
Serial controller	on-chip	Nordic nRF family UART1	nordic,nrf-uart
	on-chip	Nordic nRF family UARTE (UART with EasyDMA)1	nordic,nrf-uarte
SPI	on-chip	Nordic nRF family SPIM (SPI master with EasyDMA)3	nordic,nrf-spim
	on-chip	Nordic nRF family SPI (SPI master)1	nordic,nrf-spi
SRAM	on-chip	Generic on-chip SRAM description1	mmio-sram
Timer	on-chip	ARMv7-M System Tick1	arm,armv7m-systick
USB	on-chip	Nordic nRF52 USB device controller1	nordic,nrf-usbd
Watchdog	on-chip	Nordic nRF family WDT (Watchdog Timer)1	nordic,nrf-wdt

adafruit_feather_nrf52840/nrf52840/uf2 target

Type	Location	Description	Compatible
CPU	on-chip	ARM Cortex-M4F CPU1	arm,cortex-m4f
ADC	on-chip	Nordic Semiconductor nRF family SAADC node1	nordic,nrf-saadc
ARM architecture	on-chip	Nordic UICR (User Information Configuration Registers)1	nordic,nrf-uicr
	on-chip	Nordic EGU (Event Generator Unit)6	nordic,nrf-egu
	on-chip	Nordic nRF family ACL (Access Control List)1	nordic,nrf-acl
	on-chip	Nordic nRF family MWU (Memory Watch Unit)1	nordic,nrf-mwu
Audio	on-chip	Nordic PDM (Pulse Density Modulation interface)1	nordic,nrf-pdm
Clock control	on-chip	Nordic nRF clock control node1	nordic,nrf-clock
Comparator	on-chip	Nordic nRF COMP (analog COMParator)1	nordic,nrf-comp
Counter	on-chip	Nordic nRF timer node5	nordic,nrf-timer
Cryptographic accelerator	on-chip	Nordic ECB (AES electronic codebook mode encryption)1	nordic,nrf-ecb
	on-chip	Nordic nRF family CCM (AES CCM mode encryption)1	nordic,nrf-ccm
	on-chip	ARM TrustZone CryptoCell 3101	arm,cryptocell-310
Debug	on-chip	ARMv7 instrumentation trace macrocell1	arm,armv7m-itm
Flash controller	on-chip	Nordic NVMC (Non-Volatile Memory Controller)1	nordic,nrf52-flash-controller
	on-chip	Properties defining the interface for the Nordic QSPI peripheral1	nordic,nrf-qspi
GPIO & Headers	on-chip	NRF5 GPIOTE1	nordic,nrf-gpiote
	on-chip	NRF5 GPIO2	nordic,nrf-gpio
	on-board	GPIO pins exposed on Adafruit Feather headers1	adafruit-feather-header
I2C	on-chip	Nordic nRF family TWI (TWI master)1	nordic,nrf-twi
	on-chip	Nordic nRF family TWIM (TWI master with EasyDMA)1	nordic,nrf-twim
I2S	on-chip	Nordic I2S (Inter-IC sound interface)1	nordic,nrf-i2s
IEEE 802.15.4	on-chip	Nordic nRF IEEE 802.15.4 node1	nordic,nrf-ieee802154
IIO	on-board	Description for a voltage divider, with optional ability to measure resistance of the upper leg1	voltage-divider
Input	on-board	Group of GPIO-bound input keys1	gpio-keys
Interrupt controller	on-chip	ARMv7-M NVIC (Nested Vectored Interrupt Controller)1	arm,v7m-nvic
LED	on-board	Group of GPIO-controlled LEDs1	gpio-leds
Miscellaneous	on-chip	Nordic FICR (Factory Information Configuration Registers)1	nordic,nrf-ficr
	on-chip	Nordic nRF family PPI (Programmable Peripheral Interconnect)1	nordic,nrf-ppi
MTD	on-chip	Flash node1	soc-nv-flash
	on-chip	Fixed partitions of a flash (or other non-volatile storage) memory1	fixed-partitions
	on-board	QSPI NOR flash supporting the JEDEC CFI interface1	nordic,qspi-nor
Networking	on-chip	Nordic nRF family RADIO peripheral1	nordic,nrf-radio
	on-chip	Nordic nRF family NFCT (Near Field Communication Tag)1	nordic,nrf-nfct
Pin control	on-chip	The nRF pin controller is a singleton node responsible for controlling pin function selection and pin properties1	nordic,nrf-pinctrl
Power management	on-chip	Nordic nRF power control node1	nordic,nrf-power
PWM	on-chip	nRF PWM4	nordic,nrf-pwm
	on-chip	nRFx S/W PWM1	nordic,nrf-sw-pwm
Regulator	on-chip	Nordic nRF5X regulator (fixed stage of the core supply)1	nordic,nrf5x-regulator
	on-chip	Nordic nRF52X regulator (high voltage stage of the main supply)1	nordic,nrf52x-regulator-hv
Retained memory	on-chip	Nordic GPREGRET (General Purpose Register Retention) device2	nordic,nrf-gpregret
RNG	on-chip	Nordic nRF family RNG (Random Number Generator)1	nordic,nrf-rng
RTC	on-chip	Nordic nRF RTC (Real-Time Counter)3	nordic,nrf-rtc
Sensors	on-chip	Nordic nRF family TEMP node1	nordic,nrf-temp
	on-chip	Nordic nRF quadrature decoder (QDEC) node1	nordic,nrf-qdec
Serial controller	on-chip	Nordic nRF family UART1	nordic,nrf-uart
	on-chip	Nordic nRF family UARTE (UART with EasyDMA)1	nordic,nrf-uarte
SPI	on-chip	Nordic nRF family SPIM (SPI master with EasyDMA)3	nordic,nrf-spim
	on-chip	Nordic nRF family SPI (SPI master)1	nordic,nrf-spi
SRAM	on-chip	Generic on-chip SRAM description1	mmio-sram
Timer	on-chip	ARMv7-M System Tick1	arm,armv7m-systick
USB	on-chip	Nordic nRF52 USB device controller1	nordic,nrf-usbd
Watchdog	on-chip	Nordic nRF family WDT (Watchdog Timer)1	nordic,nrf-wdt

Connections and IOs

ExpressSense

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.

ExpressExpress UF2SenseSense UF2

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.

ExpressExpress UF2SenseSense UF2

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

1. You should see the red LED blink.

References

[1]

https://learn.adafruit.com/introducing-the-adafruit-nrf52840-feather/

[2]

https://learn.adafruit.com/introducing-the-adafruit-nrf52840-feather/pinouts

[3]

https://learn.adafruit.com/introducing-the-adafruit-nrf52840-feather/downloads

[4]

https://learn.adafruit.com/adafruit-feather-sense

[5]

https://learn.adafruit.com/adafruit-feather-sense/pinouts

[6]

https://learn.adafruit.com/adafruit-feather-sense/downloads

[7]

https://github.com/adafruit/Adafruit_nRF52_Bootloader

[8]

https://github.com/microsoft/uf2