The Adafruit Feather nRF52840 Express is the newest member of the Feather family with Bluetooth Low Energy and native USB support with the nRF52840 !  This is our point of view on an'all-in-one' Arduino-compatible + Bluetooth Low Energy with integrated USB and battery charging. With native USB, it is even ready to join the CircuitPython family.

This chip has twice as much flash, and four times as much SRAM from its brother or sister, nRF52832 - 1 MB of FLASH and 256KB of SRAM. Compared to the nRF51, this map has 4 to 8 times more of everything.

For this chip, we have added Arduino IDE support - you can program the nRF52840 chip directly to take full advantage of the Cortex-M4 processor, then call the Nordic SoftDevice radio stack when you need to communicate via BLE. Since the API and underlying devices are the same for the'832 and'840, you can overload your old nRF52832 projects with the same code, with only one recompilation!

We also chose this chip for our first BLE-compatible CircuitPython card! CircuitPython works best with access to the disk drive, and it is the only native BLE-plus-USB chip that has the memory to run a small Python interpreter. The massive RAM and the fast Cortex M4F chip make it a good choice.

Please note that at the moment, we only have BLE stack support in Arduino. Support for the CircuitPython BLE stack is still in progress!

It has tons of impressive peripherals: many GPIOs, analog inputs, PWMs, timers, etc. Best of all, it has this native USB! Finally, no need for a separate USB serial chip such as CP2104 or FT232. Serial is treated as a CDC USB descriptor, and the chip can act as a keyboard, mouse, MIDI device or even a disk drive (Note that we don't have support for anything other than CDC for Arduino at this time)

Other updates we've added are an additional'USER' switch that can be used to trigger OTA updates (or whatever you want), a NeoPixel LED for status updates, 2 MB of QSPI Flash to store CircuitPython files, and a SWD connector.

We have a number of BTLE-compatible Fetahers (it's a popular protocol!) so check the BT Feather guide for comparative information.

We pre-programmed the chip with the UF2 boot loader, which can use either UART command line programming with nrfutil (we use it for Arduino), or drag and drop mass storage, for CircuitPython installation and also because the hard disk boot loaders make firmware updating so easy. Do you want to program the chip directly? You can use our command line tools with your favorite editor and tool chain. If you want to use a SWD programmer/debugger (for even more advanced use), we have a standard 2x5 0.05" connector.

Even better, we have done everything we can to ensure that you can focus on your project from day one, thanks to the low-level BLE stack formatting! The code example works very well with our existing iOS and Android application.

Features :

    ARM Cortex M4F (with HW floating point acceleration) operating at 64MHz
    1 MB of flash memory and 256 KB of SRAM memory
    Native Open Source USB stack - pre-programmed with UF2 bootloader
    Bluetooth Low Energy 2.4GHz compatible radio (Details available in product specification nRF52840)
    FCC / IC / TELEC certified module
    Up to +8dBm output power
    Operation 1.7v to 3.3v with internal linear regulators and DC/DC voltage regulators
    21 GPIO, 6 pin ADC 12 bit, up to 12 PWM outputs (3 PWM modules with 4 outputs each)
    Pin #3 flashing red LED for general use, NeoPixel for colorful feedback.
    Power supply/activation pin
    Measures 2.0" x 0.9" x 0.28" (51mm x 23mm x 23mm x 7.2mm) without welded manifolds.
    Light as a (large?) feather - 6 grams
    4 fixing holes
    Reset button
    SWD connector for debugging
    Works in an original way with all our Adafruit feather wings! (Even those who use UART like GPS FeatherWing)

Technical details

    Dimensions (not assembled): 51mm x 23mm x 23mm x 7.2mm / 2" x 0.9" x 0.28".
    Weight: 6g