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Download the Project Bundle
Your project will use a specific set of CircuitPython libraries, and the code.py file. To get everything you need, click on the Download Project Bundle link below, and uncompress the .zip file.
Connect your computer to the Feather board via a known good USB power+data cable. A new flash drive should show up as CIRCUITPY.
Drag the contents of the uncompressed bundle directory onto your board's CIRCUITPY drive, replacing any existing files or directories with the same names, and adding any new ones that are necessary.
# SPDX-FileCopyrightText: 2023 John Park for Adafruit
# SPDX-License-Identifier: MIT
# Bricktunes LEGO Color Synth
# Feather RP2040 Prop-Maker + AS7341 Color Sensor
# Color comparison code and chime library by CGrover
import time
import math
import board
import digitalio
import audiobusio
from adafruit_as7341 import AS7341, Gain
import audiomixer
from cedargrove_chime import Chime, Voice, Material, Striker
DEBUG = False # Useful for tuning reference color values by printing them
TOLERANCE = 800 # The color matching tolerance index (0 to 8 * max_sensor_count)
sensor = AS7341(board.STEMMA_I2C())
sensor.astep = 128 # (999) The integration time step size in 2.78 microsecond increments
sensor.atime = 50 # The integration time step count.
sensor.gain = Gain.GAIN_256X
sensor.led_current = 4 # increments in units of 4
sensor.led = True
max_sensor_count = (sensor.astep + 1) * (sensor.atime + 1)
# ===================================================
# color lists as 8-channel tuples (channels[0:8])
brick_full_spectrum_values = [
(94, 1310, 1736, 1075, 592, 437, 497, 383), # Blue
(148, 324, 838, 2577, 2363, 1259, 929, 819), # Bright Green
(381, 576, 850, 1619, 3688, 5532, 6291, 4250), # Bright Lt Orange
(404, 2300, 2928, 2385, 2679, 3804, 5576, 4284), # Bright Pink
(545, 1276, 1513, 1178, 2291, 6579, 6579, 6486), # Coral
(136, 1055, 1223, 745, 748, 768, 1205, 1100), # Dark Purple
(85, 731, 1375, 1604, 1019, 557, 533, 370), # Dark Turquoise
(451, 2758, 3786, 2880, 3007, 3064, 4539, 3656), # Lavender
(214, 300, 771, 1811, 3245, 2897, 2051, 1392), # Lime
(188, 341, 435, 507, 625, 1703, 4361, 3692), # Red
(182, 870, 1455, 1799, 2149, 1879, 1702, 1273), # Sand Green
(461, 497, 878, 2412, 4699, 5935, 6579, 4677) # Yellow
]
brick_color_names = [
"Blue",
"Bright Green",
"Bright Light Orange",
"Bright Pink",
"Coral",
"Dark Purple",
"Dark Turquoise",
"Lavender",
"Lime",
"Red",
"Sand Green",
"Yellow"
]
brick_states = [False] * (len(brick_color_names))
gap_state = False
# ===================================================
# audio setup
power = digitalio.DigitalInOut(board.EXTERNAL_POWER)
power.switch_to_output(value=True)
audio_output = audiobusio.I2SOut(board.I2S_BIT_CLOCK, board.I2S_WORD_SELECT, board.I2S_DATA)
mixer = audiomixer.Mixer(sample_rate=11020, buffer_size=4096, voice_count=1, channel_count=1)
audio_output.play(mixer)
mixer.voice[0].level = 0.50 # adjust this for overall volume
brickscale = [
"C5", "D5", "E5", "F5", "G5", "A5", "B5",
"C6", "D6", "E6", "F6", "G6", "A6", "B6",
"C7", "D7", "E7", "F7", "G7", "A7", "B7",
]
# Instantiate the chime synthesizer with custom parameters
chime = Chime(
mixer.voice[0],
scale=brickscale,
material=Material.Brass, # SteelEMT, Ceramic, Wood, Copper, Aluminum, Brass
striker=Striker.HardWood, # Metal, Plexiglas, SoftWood, HardWood
voice=Voice.Tubular, # bell, perfect, tubular
scale_offset=-16
)
# Play scale notes sequentially
for index, note in enumerate(chime.scale):
chime.strike(note, 1.0)
time.sleep(0.1)
time.sleep(1)
def compare_n_channel_colors(color_1, color_2, tolerance=0):
"""Compares two integer multichannel count tuples using an unweighted linear
Euclidean difference. If the color value difference is within the tolerance
band of the reference, the method returns True.
The difference value index `tolerance` is used to detect color similarity.
Value range is an integer value from 0 to
(maximum_channel_count * number_of_channels). Default is 0 (detects a
single color value)."""
# Create list of channel deltas using list comprehension
deltas = [((color_1[idx] - count) ** 2) for idx, count in enumerate(color_2)]
# Resolve squared deltas to a Euclidean difference
# pylint: disable=c-extension-no-member
delta_color = math.sqrt(sum(deltas))
return bool(delta_color <= tolerance)
print("Bricktunes ready")
while True:
sensor_color = sensor.all_channels
# don't bother to check comparison when we're looking at a gap between bricks
if sensor_color[0] <= 70: # this checks for a minimum value on one channel
if gap_state is False:
print("no brick...")
for i in range(len(brick_color_names)):
brick_states[i] = False
gap_state = True
else:
if DEBUG:
print(sensor_color)
for i in range(len(brick_full_spectrum_values)):
color_match = compare_n_channel_colors(
sensor_color,
brick_full_spectrum_values[i],
TOLERANCE
)
if color_match is True:
if brick_states[i] is False:
for n in range(5):
chime.strike(chime.scale[i+(n*2)], 1.0)
time.sleep(0.1)
brick_states[i] = True
gap_state = False
print("sensor color:", sensor_color, "| ref:", brick_full_spectrum_values[i])
print(brick_color_names[i])
break
How It Works
The code has two key functions:
- check the color sensor to see if there is a match (within specified tolerance) to a reference color
- play a synthio arpeggio based on the matched color
Import Libraries
First, you'll import the necessary libraries:
-
time: used to create delays between notes -
math: used for some of the color comparison functions -
board: provides pin mappings for the Feather board -
digitalio: used to power on the extra peripherals of the Feather Prop-Maker (in this case the I2S amp) -
audiobusio: for sending audio to the I2S amp output -
adafruit_as7341: the color sensor library - audiomixer: used for setting the audio output volume
-
cedargrove_chime: this library from the community bundle adds note overtones and envelopes from tubular bell/chime algorithms to synthio
import time import math import board import digitalio import audiobusio from adafruit_as7341 import AS7341, Gain import audiomixer from cedargrove_chime import Chime, Voice, Material, Striker
User Parameters
The DEBUG variable can be set to True or False to switch on and off printing to the serial output of the color values. This is used for calibration.
The TOLERANCE variable sets the color matching tolerance index. It defines how close the detected color needs to be to a reference color to trigger a musical note. A higher value increases tolerance.
DEBUG = False # Useful for tuning reference color values by printing them TOLERANCE = 800 # The color matching tolerance index (0 to 8 * max_sensor_count)
Color Sensor Setup
This configures the AS7341 color sensor. It specifies integration time step, sensor gain, LED current, and whether the LED should be on or off.
sensor = AS7341(board.STEMMA_I2C()) sensor.astep = 128 # (999) The integration time step size in 2.78 microsecond increments sensor.atime = 50 # The integration time step count. sensor.gain = Gain.GAIN_256X sensor.led_current = 4 # increments in units of 4 sensor.led = True max_sensor_count = (sensor.astep + 1) * (sensor.atime + 1)
Brick Color Values & Names
Here we create two lists: measured color values of each brick on the eight channels, and the corresponding color names.
You can replace these with your own brick colors and names by copying values from the REPL.
brick_full_spectrum_values = [
(94, 1310, 1736, 1075, 592, 437, 497, 383), # Blue
(148, 324, 838, 2577, 2363, 1259, 929, 819), # Bright Green
(381, 576, 850, 1619, 3688, 5532, 6291, 4250), # Bright Lt Orange
(404, 2300, 2928, 2385, 2679, 3804, 5576, 4284), # Bright Pink
(545, 1276, 1513, 1178, 2291, 6579, 6579, 6486), # Coral
(136, 1055, 1223, 745, 748, 768, 1205, 1100), # Dark Purple
(85, 731, 1375, 1604, 1019, 557, 533, 370), # Dark Turquoise
(451, 2758, 3786, 2880, 3007, 3064, 4539, 3656), # Lavender
(214, 300, 771, 1811, 3245, 2897, 2051, 1392), # Lime
(188, 341, 435, 507, 625, 1703, 4361, 3692), # Red
(182, 870, 1455, 1799, 2149, 1879, 1702, 1273), # Sand Green
(461, 497, 878, 2412, 4699, 5935, 6579, 4677) # Yellow
]
brick_color_names = [
"Blue",
"Bright Green",
"Bright Light Orange",
"Bright Pink",
"Coral",
"Dark Purple",
"Dark Turquoise",
"Lavender",
"Lime",
"Red",
"Sand Green",
"Yellow"
]
Brick States
brick_states is a list of boolean values that keeps track of whether a specific LEGO brick color is currently detected.
gap_state keeps track of when no brick is currently detected.
brick_states = [False] * (len(brick_color_names)) gap_state = False
Audio Setup
Configuration for audio output and mixer, which is used to set the overall volume. We first have to enable external power via digitalio on the Feather Prop-Maker RP2040 (this is a power saving feature).
power = digitalio.DigitalInOut(board.EXTERNAL_POWER) power.switch_to_output(value=True) audio_output = audiobusio.I2SOut(board.I2S_BIT_CLOCK, board.I2S_WORD_SELECT, board.I2S_DATA) mixer = audiomixer.Mixer(sample_rate=11020, buffer_size=4096, voice_count=1, channel_count=1) audio_output.play(mixer) mixer.voice[0].level = 0.50 # adjust this for overall volume
Chime Setup
We'll create a scale specified in note names and octaves called brickscale and then instantiate the Chime object.
You can adjust the chime's parameters for material, stricker, voice, and scale_offset.
We then play through the scale as a startup sound.
brickscale = [
"C5", "D5", "E5", "F5", "G5", "A5", "B5",
"C6", "D6", "E6", "F6", "G6", "A6", "B6",
"C7", "D7", "E7", "F7", "G7", "A7", "B7",
]
# Instantiate the chime synthesizer with custom parameters
chime = Chime(
mixer.voice[0],
scale=brickscale,
material=Material.Brass, # SteelEMT, Ceramic, Wood, Copper, Aluminum, Brass
striker=Striker.HardWood, # Metal, Plexiglas, SoftWood, HardWood
voice=Voice.Tubular, # bell, perfect, tubular
scale_offset=-16
)
for index, note in enumerate(chime.scale):
chime.strike(note, 1.0)
time.sleep(0.1)
Color Compare Function
The function compare_n_channel_colors compares the color detected by the sensor with reference color values. It calculates the Euclidean difference between two color values and checks if it's within the specified tolerance.
From CGrover's function notes:
Compares two integer multichannel count tuples using an unweighted linear Euclidean difference. If the color value difference is within the tolerance band of the reference, the method returns True.
The difference value index `tolerance` is used to detect color similarity. Value range is an integer value from 0 to (maximum_channel_count * number_of_channels). Default is 0 (detects a single color value).
def compare_n_channel_colors(color_1, color_2, tolerance=0):
# Create list of channel deltas using list comprehension
deltas = [((color_1[idx] - count) ** 2) for idx, count in enumerate(color_2)]
# Resolve squared deltas to a Euclidean difference
# pylint: disable=c-extension-no-member
delta_color = math.sqrt(sum(deltas))
return bool(delta_color <= tolerance)
You can learn more about the color comparison function in this TV Backlight Playground post.
Main Loop
The main loop continuously reads color data from the sensor. If the color reading indicates a gap between LEGO bricks (based on the value of the first channel), it resets the state of all brick colors to "not detected."
If a color is detected, it compares the detected color to the reference colors.
If there's a match within the tolerance, it plays a musical chime note set corresponding to the detected color.
while True:
sensor_color = sensor.all_channels
# don't bother to check comparison when we're looking at a gap between bricks
if sensor_color[0] <= 70: # this checks for a minimum value on one channel
if gap_state is False:
print("no brick...")
for i in range(len(brick_color_names)):
brick_states[i] = False
gap_state = True
else:
if DEBUG:
print(sensor_color)
for i in range(len(brick_full_spectrum_values)):
color_match = compare_n_channel_colors(
sensor_color,
brick_full_spectrum_values[i],
TOLERANCE
)
if color_match is True:
if brick_states[i] is False:
for n in range(5):
chime.strike(chime.scale[i+(n*2)], 1.0)
time.sleep(0.1)
brick_states[i] = True
gap_state = False
print("sensor color:", sensor_color, "| ref:", brick_full_spectrum_values[i])
print(brick_color_names[i])
break
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