Install CircuitPython

The Adafruit Feather M4 ships with CircuitPython, but lets go ahead and update it to the latest version. It's super easy with the website, just click the link below to launch the page. There you can choose to install the latest stable release or the latest beta. 

Quick Start

  • Connect board to computer via a known good USB and double press the reset button.
  • Download the CircuitPython UF2 and upload to the FEATHERBOOT drive.
  • Open CIRCUITPY drive and upload the required libraries (listed below) and

Adafruit Circuit Python Libraries

Download the CircuitPython library bundle and unzip the folder. Create a new folder on the CIRCUITPY drive and name it lib. The following libraries are required to run the code properly. Double check to ensure all of the files and folders are inside the lib folder on the CIRCUITPY drive.

  • adafruit_bus_device (directory)
  • adafruit_lis3dh.mpy
  • neopixel.mpy

Upload Files

Click the link below to download the project zip – This contains the code and audio files. Upload the file to the CIRCUITPY drive root (main) folder.

Create a new folder on the CIRCUITPY drive and name it sounds. Upload the audio files to that folder. The code will run properly when all of the files have been uploaded.

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

Prop-Maker based Master Sword
Adafruit invests time and resources providing this open source code.
Please support Adafruit and open source hardware by purchasing
products from Adafruit!
Written by Kattni Rembor & Limor Fried for Adafruit Industries
Copyright (c) 2019-2020 Adafruit Industries
Licensed under the MIT license.
All text above must be included in any redistribution.

import time
import random
import digitalio
import audioio
import audiocore
import board
import neopixel
import adafruit_lis3dh

COLOR = (0, 120, 120)      # Default idle is light blue
ALT_COLOR = (255, 50, 0)  # hit color is orange

# CUSTOMISE IDLE PULSE SPEED HERE: 0 is fast, above 0 slows down
IDLE_PULSE_SPEED = 0  # Default is 0 seconds

# CUSTOMISE BRIGHTNESS HERE: must be a number between 0 and 1
IDLE_PULSE_BRIGHTNESS_MIN = 0.2  # Default minimum idle pulse brightness
IDLE_PULSE_BRIGHTNESS_MAX = 1  # Default maximum idle pulse brightness

# CUSTOMISE SENSITIVITY HERE: smaller numbers = more sensitive to motion

# Set to the length in seconds of the "on.wav" file

NUM_PIXELS = 83  # Number of pixels used in project
POWER_PIN = board.D10

enable = digitalio.DigitalInOut(POWER_PIN)
enable.direction = digitalio.Direction.OUTPUT
enable.value = False

strip = neopixel.NeoPixel(NEOPIXEL_PIN, NUM_PIXELS, brightness=1, auto_write=False)
strip.fill(0)  # NeoPixels off ASAP on startup

audio = audioio.AudioOut(board.A0)  # Speaker
wave_file = None

# Set up accelerometer on I2C bus, 4G range:
i2c = board.I2C()  # uses board.SCL and board.SDA
# i2c = board.STEMMA_I2C()  # For using the built-in STEMMA QT connector on a microcontroller
accel = adafruit_lis3dh.LIS3DH_I2C(i2c)
accel.range = adafruit_lis3dh.RANGE_4_G

COLOR_IDLE = COLOR # 'idle' color is the default
COLOR_HIT = ALT_COLOR  # "hit" color is ALT_COLOR set above
COLOR_SWING = ALT_COLOR  # "swing" color is ALT_COLOR set above

def play_wav(name, loop=False):
    Play a WAV file in the 'sounds' directory.
    :param name: partial file name string, complete name will be built around
                 this, e.g. passing 'foo' will play file 'sounds/foo.wav'.
    :param loop: if True, sound will repeat indefinitely (until interrupted
                 by another sound).
    global wave_file  # pylint: disable=global-statement
    print("playing", name)
    if wave_file:
        wave_file = open('sounds/' + name + '.wav', 'rb')
        wave = audiocore.WaveFile(wave_file), loop=loop)
    except OSError:
        pass # we'll just skip playing then

def power_on(sound, duration):
    Animate NeoPixels with accompanying sound effect for power on.
    :param sound: sound name (similar format to play_wav() above)
    :param duration: estimated duration of sound, in seconds (>0.0)
    prev = 0
    start_time = time.monotonic()  # Save audio start time
    while True:
        elapsed = time.monotonic() - start_time  # Time spent playing sound
        if elapsed > duration:  # Past sound duration?
            break  # Stop animating
        animation_time = elapsed / duration  # Animation time, 0.0 to 1.0
        threshold = int(NUM_PIXELS * animation_time + 0.5)
        num = threshold - prev  # Number of pixels to light on this pass
        if num != 0:
            strip[prev:threshold] = [ALT_COLOR] * num
            prev = threshold

def mix(color_1, color_2, weight_2):
    Blend between two colors with a given ratio.
    :param color_1:  first color, as an (r,g,b) tuple
    :param color_2:  second color, as an (r,g,b) tuple
    :param weight_2: Blend weight (ratio) of second color, 0.0 to 1.0
    :return (r,g,b) tuple, blended color
    if weight_2 < 0.0:
        weight_2 = 0.0
    elif weight_2 > 1.0:
        weight_2 = 1.0
    weight_1 = 1.0 - weight_2
    return (int(color_1[0] * weight_1 + color_2[0] * weight_2),
            int(color_1[1] * weight_1 + color_2[1] * weight_2),
            int(color_1[2] * weight_1 + color_2[2] * weight_2))

# List of swing wav files without the .wav in the name for use with play_wav()
swing_sounds = [

# List of hit wav files without the .wav in the name for use with play_wav()
hit_sounds = [

mode = 0  # Initial mode = OFF

# Setup idle pulse
idle_brightness = IDLE_PULSE_BRIGHTNESS_MIN  # current brightness of idle pulse
idle_increment = 0.01  # Initial idle pulse direction

# Main loop
while True:

    if mode == 0:  # If currently off...
        enable.value = True
        power_on('on', POWER_ON_SOUND_DURATION)  # Power up!
        play_wav('idle', loop=True)  # Play idle sound now
        mode = 1  # Idle mode

        # Setup for idle pulse
        idle_brightness = IDLE_PULSE_BRIGHTNESS_MIN
        idle_increment = 0.01
        strip.fill([int(c*idle_brightness) for c in COLOR])

    elif mode >= 1:  # If not OFF mode...
        x, y, z = accel.acceleration  # Read accelerometer
        accel_total = x * x + z * z
        # (Y axis isn't needed, due to the orientation that the Prop-Maker
        # Wing is mounted.  Also, square root isn't needed, since we're
        # comparing thresholds...use squared values instead.)
        if accel_total > HIT_THRESHOLD:  # Large acceleration = HIT
            TRIGGER_TIME = time.monotonic()  # Save initial time of hit
            play_wav(random.choice(hit_sounds))  # Start playing 'hit' sound
            COLOR_ACTIVE = COLOR_HIT  # Set color to fade from
            mode = 3  # HIT mode
        elif mode == 1 and accel_total > SWING_THRESHOLD:  # Mild = SWING
            TRIGGER_TIME = time.monotonic()  # Save initial time of swing
            play_wav(random.choice(swing_sounds))  # Randomly choose from available swing sounds
            # make a larson scanner animation_time
            strip_backup = strip[0:-1]
            for p in range(-1, len(strip)):
                for i in range (p-1, p+2): # shoot a 'ray' of 3 pixels
                    if 0 <= i < len(strip):
                        strip[i] = COLOR_SWING
                if 0 <= (p-1) < len(strip):
                    strip[p-1] = strip_backup[p-1]  # restore previous color at the tail
            while audio.playing:
                pass # wait till we're done
            mode = 2  # we'll go back to idle mode

        elif mode == 1:
            # Idle pulse
            idle_brightness += idle_increment  # Pulse up
            if idle_brightness > IDLE_PULSE_BRIGHTNESS_MAX or \
               idle_brightness < IDLE_PULSE_BRIGHTNESS_MIN:  # Then...
                idle_increment *= -1  # Pulse direction flip
            strip.fill([int(c*idle_brightness) for c in COLOR_IDLE])
            time.sleep(IDLE_PULSE_SPEED)  # Idle pulse speed set above
        elif mode > 1:  # If in SWING or HIT mode...
            if audio.playing:  # And sound currently playing...
                blend = time.monotonic() - TRIGGER_TIME  # Time since triggered
                if mode == 2:  # If SWING,
                    blend = abs(0.5 - blend) * 2.0  # ramp up, down
                strip.fill(mix(COLOR_ACTIVE, COLOR, blend))  # Fade from hit/swing to base color
            else:  # No sound now, but still SWING or HIT modes
                play_wav('idle', loop=True)  # Resume idle sound
                mode = 1  # Return to idle mode

Mu Python Editor

Check out Mu, it's 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!

Audio Files

The sounds used in this project were created with samples from Video CoPilots Motion Pulse sound pack. Hits and swings were mixed with captured sounds in-game from Zelda: BOTW.

This pack contains sounds that are already in the supported audio format.

Adafruit CircuitPython supports 16-bit, Mono, 22.050kHz .wav audio format. See this guide to help format any audio files you might want to use in this project besides the files provided.

In the main loop, the swing and hit modes randomly choose from a list of sounds. For example, swing1.wav, swing2.wav, swing3, etc. This makes the motion effects feel much more varied and less repetitive.

  • Power on – on.wav
  • Idle loop – idle.wav
  • Swing 1 – swing1.wav
  • Swing 2 – swing2.wav
  • Swing 3 – swing3.wav
  • Swing 4 – swing4.wav
  • Hit 1 – hit1.wav
  • Hit 2 – hit2.wav
  • Hit 3 – hit3.wav
  • Hit 4 – hit4.wav

This guide was first published on Jul 30, 2019. It was last updated on May 22, 2024.

This page (Software) was last updated on May 22, 2024.

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