circuitpython/ports/nrf/boards/feather52840

Setup

The feather52840 board is currently based on the PCA10056 development board from Nordic Semiconductors, since commercial modules are not yet available for the nRF52840.

The difference between the pca10056 and feather52840 board support packages is that no bootloader is present on the pca10056 (a HW debugger like a Segger J-Link is required to flash firmware images), whereas the feather52840 package uses a serial bootloader, with a slightly different flash layout to account for the bootloader's presence.

Both targets run on the same hardware and assume the same pinouts.

The feather52840 board support package will be updated at a later date to reflect any pin changes in the final Feather form-factor HW.

Installing CircuitPython submodules

Before you can build, you will need to run the following commands once, which will install the submodules that are part of the CircuitPython ecosystem, and build the mpy-cross tool:

$ cd circuitpython
$ git submodule update --init
$ make -C mpy-cross

You then need to download the SD and Nordic SDK files via:

This script relies on wget, which must be available from the command line.

$ cd ports/nrf
$ ./drivers/bluetooth/download_ble_stack.sh

Installing the Serial Bootloader

The Adafruit nRF52840 Feather uses a serial bootloader that allows you to update the core CircuitPython firmware and internal file system contents using only a serial connection.

On empty devices, the serial bootloader will need to be flashed once using a HW debugger such as a Segger J-Link before the serial updater (nrfutil) can be used.

Install nrfjprog

Before you can install the bootloader, you will first need to install the nrfjprog tool from Nordic Semiconductors for your operating system. The binary files can be downloaded via the following links:

• nRF5x toolset tar for Linux 32-bit v9.7.2
• nRF5x toolset tar for Linux 64-bit v9.7.2
• nRF5x toolset tar for OSX v9.7.2
• nRF5x toolset installer for Windows v9.7.2

You will then need to add the nrfjprog folder to your system PATH variable so that it is available from the command line. The exact process for this is OS specific, but on a POSIX type system like OS X or Linux, you can temporarily add the location to your PATH environment variables as follows:

$ export PATH=$PATH:YOURPATHHERE/nRF5x-Command-Line-Tools_9_7_2_OSX/nrfjprog/

You can test this by running the following command:

$ nrfjprog --version
nrfjprog version: 9.7.2
JLinkARM.dll version: 6.20f

Flash the Bootloader with nrfjprog

This operation only needs to be done once, and only on boards that don't already have the serial bootloader installed.

Once nrfjprog is installed and available in PATH you can flash your board with the serial bootloader via the following command:

make SD=s140 BOARD=feather52840 boot-flash

This should give you the following (or very similar) output, and you will see a DFU blinky pattern on one of the board LEDs:

$ make SD=s140 BOARD=feather52840 boot-flash
Use make V=1, make V=2 or set BUILD_VERBOSE similarly in your environment to increase build verbosity.
nrfjprog --program boards/feather52840/bootloader/feather52840_bootloader_6.0.0_s140_single.hex -f nrf52 --chiperase --reset
Parsing hex file.
Erasing user available code and UICR flash areas.
Applying system reset.
Checking that the area to write is not protected.
Programing device.
Applying system reset.
Run.

From this point onward, you can now use a simple serial port for firmware updates.

Building and Flashing CircuitPython

Installing nrfutil

If you haven't installed the required command-line tool yet, go to the /libs/nrfutil folder (where nrfutil 0.5.2 is installed as a sub-module) and run the following commands:

If you get a 'sudo: pip: command not found' error running 'sudo pip install', you can install pip via 'sudo easy_install pip'

$ cd ../../lib/nrfutil
$ sudo pip install -r requirements.txt
$ sudo python setup.py install

Flashing CircuitPython

With the serial bootloader present on your board, you can build and flash a CircuitPython binary via the following command:

make SD=s140 SERIAL=/dev/ttyACM0 BOARD=feather52840 dfu-gen dfu-flash