Adafruit nRF52840 Feather Express Add-On Board

Adafruit nRF52840 Feather Express Add-On Board is a BLUETOOTH® Low Energy and native USB support device featuring the nRF52840. The board is an all-in-one Arduino-compatible + BLUETOOTH Low Energy with built-in USB plus battery charging. Native USB means it's ready to join the CircuitPython party. This chip has twice the Flash and four times the SRAM of the nRF52832 (1MB of Flash and 256KB of SRAM). Compared to the nRF51, this board has four to eight times more of everything.

Features

ARM Cortex M4F (with HW floating point acceleration) running at 64MHz
1MB flash and 256KB SRAM
Native Open Source USB stack - pre-programmed with UF2 bootloader
BLUETOOTH Low Energy compatible 2.4GHz radio (Details available in the nRF52840 product specification)
FCC-, IC-, and TELEC-certified module
Up to +8dBm output power
1.7V to 3.3V operation with internal linear and DC/DC voltage regulators
21x GPIO, 6x 12-bit ADC pins, up to 12x PWM outputs (3x PWM modules with 4x outputs each)

Pin #3 red LED for general purpose blinking, NeoPixel for colorful feedback
Power/enable pin
Measures 2.0" x 0.9" x 0.28" (51mm x 23mm x 7.2mm) without headers soldered in
6g in weight
4x mounting holes
Reset button
SWD connector for debugging
Works out of the box with all Adafruit FeatherWings (Even the UART-using ones like the GPS FeatherWing)