Setup ItsyBitsy nRF52840 with CircuitPython

We'll need to get our board setup so we can run the CircuitPython code. Let's walk through these steps to get the latest version of CircuitPython onto your board. 

The Mu Python Editor

Mu is a simple Python editor that works with Adafruit CircuitPython hardware. It's written in Python and works on Windows, MacOS, Linux and Raspberry Pi. The serial console is built right in, so you get immediate feedback from your board's serial output! While you can use any text editor with your code, Mu makes it super simple. Instructions for Mu are available here.

Installing or upgrading CircuitPython

You should ensure you have CircuitPython 4.0 or greater on your board. Plug your board in with a known good data + power cable (not the cheesy USB cable that comes with USB power packs, they are power only). You should see a new flash drive pop up.

If the drive is CIRCUITPY, then open the boot_out.txt file to ensure the version number is 4.0 or greater. 

Adafruit CircuitPython 5.0.0-beta.3 on 2020-01-08; Adafruit ItsyBitsy nRF52840 Express with nRF52840

If you need to install or upgrade CircuitPython, see this guide page on the ItsyBitsy nRF52840.

Download the Adafruit CircuitPython Library Bundle

In order to run the code, we'll need to download a few libraries. Libraries contain code to help interface with hardware a lot easier for us.

Use the ItsyBitsy nRF52840 page on Installing Libraries to get the library that matches the major version of CircuitPython you are using noted above, i.e. 4.x for the versiond starting with 4, 5.x for the versions starting with 5, etc.

To run the code for this project, we need the two libraries in the Required Libraries list below. Unzip the library bundle and search for the libraries. Drag and drop the files into a folder named lib on the CIRCUITPY drive (create the folder if it is not already on the ItsyBitsy nRF52840).

Required Libraries 

  • neopixel.mpy
  • adafruit_dotstar.mpy
  • adafruit_bluefruit_connect
  • adafruit_ble
  • adafruit_led_animation

Once we have all the files we need, a directory listing will look similar to above as far as files and directories.

Upload Code

Click on the download link below to grab the main code directly from GitHub. Rename the file to and drop it onto the CIRCUITPY drive main (root) directory. The code will run properly when all of the files have been uploaded including libraries.

Use any text editor or favorite IDE to modify the code. We suggest using Mu as noted above.

# SPDX-FileCopyrightText: 2019 Kattni Rembor for Adafruit Industries
# SPDX-License-Identifier: MIT

Code for ItsyBitsy nRF52840 Infinity Cube.

import board
import neopixel
from adafruit_led_animation.animation.comet import Comet
from adafruit_led_animation.animation.sparkle import Sparkle
from import AnimationGroup
from adafruit_led_animation.sequence import AnimationSequence
import adafruit_led_animation.color as color

from adafruit_ble import BLERadio
from adafruit_ble.advertising.standard import ProvideServicesAdvertisement
from import UARTService

from adafruit_bluefruit_connect.packet import Packet
from adafruit_bluefruit_connect.color_packet import ColorPacket
from adafruit_bluefruit_connect.button_packet import ButtonPacket

# The number of NeoPixels in the externally attached strip
# If using two strips connected to the same pin, count only one strip for this number!

# Setup for comet animation
COMET_SPEED = 0.05  # Lower numbers increase the animation speed
STRIP_COMET_TAIL_LENGTH = 10  # The length of the comet on the NeoPixel strip
STRIP_COMET_BOUNCE = False  # Set to False to stop comet from "bouncing" on NeoPixel strip

# Setup for sparkle animation
SPARKLE_SPEED = 0.1  # Lower numbers increase the animation speed

# Create the NeoPixel strip
strip_pixels = neopixel.NeoPixel(board.D5, STRIP_PIXEL_NUMBER, auto_write=False)

# Setup BLE connection
ble = BLERadio()
uart = UARTService()
advertisement = ProvideServicesAdvertisement(uart)

# Setup animations
animations = AnimationSequence(
        Sparkle(strip_pixels, SPARKLE_SPEED, color.TEAL)
        Comet(strip_pixels, COMET_SPEED, color.TEAL, tail_length=STRIP_COMET_TAIL_LENGTH,

animation_color = None
mode = 0
blanked = False

while True:
    ble.start_advertising(advertisement)  # Start advertising.
    was_connected = False
    while not was_connected or ble.connected:
        if not blanked:  # If LED-off signal is not being sent...
            animations.animate()  # Run the animations.
        if ble.connected:  # If BLE is connected...
            was_connected = True
            if uart.in_waiting:  # Check to see if any data is available.
                    packet = Packet.from_stream(uart)  # Create the packet object.
                except ValueError:
                if isinstance(packet, ColorPacket):  # If the packet is color packet...
                    if mode == 0:  # And mode is 0...
                        animations.color = packet.color  # Update the animation to the color.
                        print("Color:", packet.color)
                        animation_color = packet.color  # Keep track of the current color...
                    elif mode == 1:  # Because if mode is 1...
                        animations.color = animation_color  # Freeze the animation color.
                        print("Color:", animation_color)
                elif isinstance(packet, ButtonPacket):  # If the packet is a button packet...
                    if packet.pressed:  # If the buttons in the app are pressed...
                        if packet.button == ButtonPacket.LEFT:  # If left arrow is pressed...
                            print("A pressed: animation mode changed.")
                    # Change to the next animation.
                        elif packet.button == ButtonPacket.RIGHT:  # If right arrow is pressed...
                            mode += 1  # Increase the mode by 1.
                            if mode == 1:  # If mode is 1, print the following:
                                print("Right pressed: color frozen!")
                            if mode > 1:  # If mode is > 1...
                                mode = 0  # Set mode to 0, and print the following:
                                print("Right pressed: color changing!")

Double Check

See the directory listing above and double check that you have all the files listed to make this project function. If any are missing or in an incorrect directory, move them so they're in the right places.

This guide was first published on Jan 14, 2020. It was last updated on Jun 13, 2024.

This page (Software) was last updated on Jun 13, 2024.

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