You can also code your glowing friend with CircuitPython!

CircuitPython is designed to simplify experimentation and education on low-cost microcontrollers. It makes it easier than ever to get prototyping by requiring no upfront desktop software downloads. Simply copy and edit files on the CIRCUITPY drive to iterate.

Are you new to using CircuitPython? No worries, there is a full getting started guide here.

Adafruit suggests using the Mu editor to edit your code and have an interactive REPL in CircuitPython. You can learn about Mu and its installation in this tutorial.

Follow this guide for instructions on installing the latest release version of CircuitPython for the Feather M0 Adalogger.

Yes, even though we're using the Feather M0 Bluefruit LE, the .uf2 file we're using is that for the Feather M0 Adalogger!


You'll also need to add the following libraries for this project. Follow this guide on adding libraries. The ones you'll need are:

  • adafruit_bus_device
  • adafruit_lis3dh

Download the latest adafruit-circuitpython-bundle .zip file as linked in the guide. Then,  unzip the file and drag those libraries to the lib folder on your Feather.


Here is the code we'll use. Copy it and then paste in Mu. Save it to your Feather as

# RGB Color Picker demo - wire up RGB LEDs and set their color
# using Adafruit Bluefruit Connect App on your phone
# runs on Feather M0 Bluefruit LE running the Feather M0 Adalogger build
# of CircuitPython with Prop-Maker Wing and 3W RGB LED

import time
import random
import board
import busio
import pwmio
from digitalio import DigitalInOut, Direction
from adafruit_bluefruitspi import BluefruitSPI
import adafruit_lis3dh

ADVERT_NAME = b'BlinkaNeoLamp'

# RGB LED on D11, 12, 13, we're using a Prop Maker wing
red_led = pwmio.PWMOut(board.D11, frequency=50000, duty_cycle=0)
green_led = pwmio.PWMOut(board.D12, frequency=50000, duty_cycle=0)
blue_led = pwmio.PWMOut(board.D13, frequency=50000, duty_cycle=0)
# Prop maker wing has a power pin for the LED!
power_pin = DigitalInOut(board.D10)
power_pin.direction = Direction.OUTPUT
power_pin.value = True

spi_bus = busio.SPI(board.SCK, MOSI=board.MOSI, MISO=board.MISO)
cs = DigitalInOut(board.D8)
irq = DigitalInOut(board.D7)
rst = DigitalInOut(board.D4)
bluefruit = BluefruitSPI(spi_bus, cs, irq, rst, debug=False)

i2c = busio.I2C(board.SCL, board.SDA)
lis3dh = adafruit_lis3dh.LIS3DH_I2C(i2c)

def init_bluefruit():
    # Initialize the device and perform a factory reset
    print("Initializing the Bluefruit LE SPI Friend module")
    bluefruit.command_check_OK(b'AT+FACTORYRESET', delay=1)
    # Print the response to 'ATI' (info request) as a string
    print(str(bluefruit.command_check_OK(b'ATI'), 'utf-8'))
    # Change advertised name

def wait_for_connection():
    print("Waiting for a connection to Bluefruit LE Connect ...")
    # Wait for a connection ...
    dotcount = 0
    while not bluefruit.connected:
        print(".", end="")
        dotcount = (dotcount + 1) % 80
        if dotcount == 79:

# This code will check the connection but only query the module if it has been
# at least 'n_sec' seconds. Otherwise it 'caches' the response, to keep from
# hogging the Bluefruit connection with constant queries
connection_timestamp = None
is_connected = None
def check_connection(n_sec):
    # pylint: disable=global-statement
    global connection_timestamp, is_connected
    if (not connection_timestamp) or (time.monotonic() - connection_timestamp > n_sec):
        connection_timestamp = time.monotonic()
        is_connected = bluefruit.connected
    return is_connected

# Unlike most circuitpython code, this runs in two loops
# one outer loop manages reconnecting bluetooth if we lose connection
# then one inner loop for doing what we want when connected!
while True:
    # Initialize the module
    try:        # Wireless connections can have corrupt data or other runtime failures
                # This try block will reset the module if that happens
        while True:
            # Once connected, check for incoming BLE UART data
            if check_connection(3):  # Check our connection status every 3 seconds
                # OK we're still connected, see if we have any data waiting
                resp = bluefruit.read_packet()
                if not resp:
                    continue  # nothin'
                print("Read packet", resp)
                # Look for a 'C'olor packet
                if resp[0] != 'C':
                # Set the LEDs to the three bytes in the packet
                red_led.duty_cycle = int(resp[1]/255 * 65535)
                green_led.duty_cycle = int(resp[2]/255 * 65535)
                blue_led.duty_cycle = int(resp[3]/255 * 65535)
            else:  # Not connected
                # print(lis3dh.acceleration)
                if lis3dh.acceleration.y < -5:
                    red_led.duty_cycle = random.randint(0, 65535)
                    green_led.duty_cycle = random.randint(0, 65535)
                    blue_led.duty_cycle = random.randint(0, 65535)

    except RuntimeError as e:
        print(e)  # Print what happened
        continue  # retry!


Once you've saved the file to the board, the LED will light up! For info on testing it with the Bluefruit App, head back to the previous page in this guide, to the section on Testing.

This guide was first published on Nov 06, 2018. It was last updated on Nov 06, 2018.

This page (Code with CircuitPython) was last updated on Apr 21, 2021.

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