nRF52840 Development with Arduino and CircuitPython
jimblom 
CircuitPython Installation
Are you looking for an escape from C/C++ or Arduino? Want to turn your nRF52840 into a Python-interpreting wonder? Check out the nRF port of CircuitPython!
Alpha Development
Please note that development on the CircuitPython port for the nRF52840 is still in very early stages of development. You're part of something exciting, but things might not always work as expected.
If you ever find your nRF52840 in an unknown state, you can always factory reset it -- essentially erasing any application and preserving the bootloader. For instructions on factory resetting, check out the Pro nRF52840 Mini Hookup Guide.
Flashing CircuitPython
The nRF52840's UF2 bootloader, which presents a drag-and-drop, USB mass-storage-device-based programming interface, can be used to flash CircuitPython onto your board.
To begin, download our latest release of the CircuitPython firmware. It's packaged as a .UF2 file.
Next put your nRF52840 Mini into bootload mode. Either double-tap the reset button, or hold pin-13 down while tapping the reset button. Your computer should find an "NRF52BOOT" device that looks like a removable USB drive.
Now simply drag the UF2 file onto NRF52BOOT. After the file copies over, you may get a warning indicating that the file is too large -- this should be safe to ignore (hit "Cancel").
After the firmware is programmed, a new drive should pop up on your computer: CIRCUITPY. Just as you programmed the firmware on, you'll drag-and-drop Python files into this folder to run new applications.