"Lovely Music Generator" For CircuitPython by LIXIE LABS

code.py

# ----------------------------------------------------------------------------
# LOVELY MUSIC GENERATOR by LIXIE LABS
# https://leds.social/@lixielabs
#
# Plays random notes/chords from the Amaj7 scale in a pleasing fashion using
# audiopwmio to drive a speaker with five synthio sine voices and ADSR envelopes.

# Import dependencies
import time
import board
import synthio
import audiopwmio
import array
import math
import random

# ----------------------------------------------------------------------------
# USER VARIABLES

# You can use the speaker directly, but it's MUCH louder to use a PAM8503 3W Audio Amplifier PCB  (https://www.amazon.com/ALAMSCN-Speaker-Loudspeaker-Amplifier-Replacement/dp/B0953B5KMJ/ref=sr_1_6)
SPEAKER_PWM_PIN = board.GP15

# Some of the AMaj7 scale in MIDI note numbers:
MUSICAL_SCALE = [40, 42, 44, 45, 47, 49, 50, 52, 54, 56, 57, 59, 61, 62, 64, 66, 68, 69, 71, 73, 74, 76, 78]

# How much to transpose the scale (default +2 octaves)
TRANSPOSITION = 12

# Should the ADSR envelope evolve slightly over time?
envelope_changes = True

# ----------------------------------------------------------------------------
# AUDIO SETUP SECTION

# Initialize PWM audio output on SPEAKER_PIN
audio = audiopwmio.PWMAudioOut(SPEAKER_PWM_PIN, quiescent_value = 32768)

# Render waveform data for use by synthio (single sine cycle)
synth_waveform = array.array('h')

wave_sample_count = 1024

for i in range(wave_sample_count):
    sine_value = math.sin(2 * math.pi * (i / wave_sample_count)) * 0.2
    adjusted_value = int(((sine_value + 1) / 2) * 65535) - 32768
    
    synth_waveform.append(adjusted_value)

# Define the note ADSR envelope timings
adsr_envelope = synthio.Envelope(
    attack_time   = 0.05,    # Attack time in seconds
    decay_time    = 0.50,    # Decay time in seconds
    release_time  = 1.00,    # Release time in seconds
    attack_level  = 1.00,    # Peak volume of the attack phase (0.0 to 1.0)
    sustain_level = 0.40     # Volume of the sustain phase relative to the attack level (0.0 to 1.0)
)

# Initialize the synthesizer
synth = synthio.Synthesizer(sample_rate=44100, envelope=adsr_envelope, waveform=synth_waveform)

# Start the audio engine
audio.play(synth)

# ----------------------------------------------------------------------------
# LOVELY MUSIC SECTION

# This stores currently playing notes
notes = [0, 0, 0, 0, 0]

# Start looping forever now
while True:
    # Iterate through 5 voices
    for i in range(len(notes)):
        # If 1 in 10 chance:
        if random.randint(0, 10) < 1:
            # Play random new note from MUSICAL_SCALE + TRANSPOSITION using this voice
            synth.release((notes[i]))
            notes[i] = MUSICAL_SCALE[random.randint(0, len(MUSICAL_SCALE) - 1)] + TRANSPOSITION
            synth.press((notes[i]))

            # If 1 in 10 chance: (1 in 100 since note changes are already 1 in 10) alter the ADSR envelope
            if random.randint(0, 10) < 1 and envelope_changes == True:
                new_adsr_envelope = synthio.Envelope(
                    attack_time   = (random.randint(10,100) / 500.0),    # Attack time in seconds
                    decay_time    = (random.randint(10,100) / 500.0),    # Decay time in seconds
                    release_time  = (random.randint(10,100) / 150.0),    # Release time in seconds
                    attack_level  = 1.00,    # Peak volume of the attack phase (0.0 to 1.0)
                    sustain_level = 0.10     # Volume of the sustain phase relative to the attack level (0.0 to 1.0)
                )
                synth.envelope = new_adsr_envelope

    # Keeps playback speed in check
    time.sleep(0.4)