CircuitPython Port To The Nordic Semiconductor nRF52 Series

This is a port of CircuitPython to the Nordic Semiconductor nRF52 series of chips.

Supported Features

  • UART
  • SPI
  • LEDs
  • Pins
  • ADC
  • I2C
  • PWM
  • Temperature
  • RTC (Real Time Counter. Low-Power counter)
  • BLE support including:
    • Peripheral role
    • Scanner role
    • REPL over Bluetooth LE (optionally using WebBluetooth)
    • ubluepy: Bluetooth LE module for CircuitPython
    • 1 non-connectable advertiser while in connection

Tested Hardware

Board Specific Instructions

For board-specific instructions on building and flashing CircuitPython, see the following links:

NOTE: These board specific readmes may be more up to date than the generic board-neutral documentation further down.
  • Adafruit Feather nRF52840: boards/feather_nrf52840_express/README.md: 1MB Flash, 256KB SRAM
  • Nordic PCA10056 (uses nRF52840): boards/pca10056/README.md
  • MakerDiary nRF52840 MDK: boards/makerdiary_nrf52840_mdk/README.md
  • MakerDiary nRF52840 MDK USB Dongle: boards/makerdiary_nrf52840_mdk_usb_dongle/README.md

For all other board targets, see the generic notes below.

Compile and Flash

Prerequisite steps for building the nrf port:

git clone <URL>.git circuitpython
cd circuitpython
git submodule update --init
make -C mpy-cross

To build and flash issue the following command inside the ports/nrf/ folder:

make BOARD=pca10056
make BOARD=pca10056 flash

Compile and Flash with Bluetooth Stack

First prepare the bluetooth folder by downloading Bluetooth LE stacks and headers:

 ./bluetooth/download_ble_stack.sh

If the Bluetooth stacks has been downloaded, compile the target with the following command:

make BOARD=pca10040 SD=s132

The make sd will trigger a flash of the bluetooth stack before that application is flashed. Note that make sd will perform a full erase of the chip, which could cause 3rd party bootloaders to also be wiped.

make BOARD=pca10040 SD=s132 sd

Note: further tuning of features to include in bluetooth or even setting up the device to use REPL over Bluetooth can be configured in the bluetooth_conf.h.

Target Boards and Make Flags

Target Board (BOARD) | Bluetooth Stack (SD) | Bluetooth Support | Flash Util ————————-|————————-|————————|——————————- pca10056 | s140 | Peripheral and Scanner | Segger feather_nrf52840_express | s140 | Peripheral and Scanner | UF2 bootloader makerdiary_nrf52840_mdk | s140 | Peripheral and Scanner | pyocd or ARM mbed DAPLink makerdiary_nrf52840_mdk_usb_dongle | s140 | Peripheral and Scanner | DFU bootloader & nrfutil electronut_labs_papyr | s140 | Peripheral and Scanner | UF2 bootloader electronut_labs_blip | s140 | Peripheral and Scanner | Black Magic Probe

Segger Targets

Install the necessary tools to flash and debug using Segger:

JLink Download

nrfjprog linux-32bit Download

nrfjprog linux-64bit Download

nrfjprog osx Download

nrfjprog win32 Download

note: On Linux it might be required to link SEGGER’s libjlinkarm.so inside nrfjprog’s folder.

DFU Targets

run follow command to install adafruit-nrfutil from PyPi

$ pip3 install --user adafruit-nrfutil

make flash and make sd will not work with DFU targets. Hence, dfu-gen and dfu-flash must be used instead.

  • dfu-gen: Generates a Firmware zip to be used by the DFU flash application.
  • dfu-flash: Triggers the DFU flash application to upload the firmware from the generated Firmware zip file.

Example on how to generate and flash feather_nrf52840 target:

make BOARD=feather_nrf52840 SD=s140
make BOARD=feather_nrf52840 SD=s140 dfu-gen dfu-flash

Bluetooth LE REPL

The port also implements a BLE REPL driver. This feature is disabled by default, as it will deactivate the UART REPL when activated. As some of the nRF devices only have one UART, using the BLE REPL free’s the UART instance such that it can be used as a general UART peripheral not bound to REPL.

The configuration can be enabled by editing the bluetooth_conf.h and set MICROPY_PY_BLE_NUS to 1.

When enabled you have different options to test it:

Other:

  • nRF UART application for IPhone/Android

WebBluetooth mode can also be configured by editing bluetooth_conf.h and set BLUETOOTH_WEBBLUETOOTH_REPL to 1. This will alternate advertisement between Eddystone URL and regular connectable advertisement. The Eddystone URL will point the phone or PC to download WebBluetooth REPL (experimental), which subsequently can be used to connect to the Bluetooth REPL from the PC or Phone browser.