trellism4_wavefile_synth.py

"""
This synthesizer is loaded with wave files for 3 octaves of notes each in 4 different waveforms.
It uses Mixer to play up to 7 notes at once.
Play notes with the rainbow buttons. Change waveform types ith the white buttons in the last column.
"""
import board
from audiocore import WaveFile
from audioio import AudioOut
from audiomixer import Mixer
import adafruit_trellism4

# trellis helper object
trellis = adafruit_trellism4.TrellisM4Express()
# low brightness on the neopixles
trellis.pixels.brightness = 0.05
# each musical note letter
note_letters = ["C", "D", "E", "F", "G", "A", "B"]
# colors of the rainbow
colors = [
    (255, 0, 0),
    (255, 127, 0),
    (255, 255, 0),
    (0, 255, 0),
    (0, 0, 255),
    (56, 43, 105),
    (139, 0, 255),
]

# dictionary holding note string to wave file value.
# e.g. {... "sined4": audioio.WaveFile(open("notes/sine/d4.wav")), ...}
notes = {}

# list of all waveform types
WAVE_TYPES = ["sine", "square", "sawtooth", "triangle"]

# current waveform type. Will get changed from the last column
current_wave_type = "sine"

# load the notes dictionary
for wave_type in WAVE_TYPES:
    for octave in range(3, 6):  # [3,4,5]
        for note_letter in note_letters:
            # note with octave e.g. a4
            cur_note = "{}{}".format(note_letter, octave)
            # add wave file to dictionary
            key = "{}{}".format(wave_type, cur_note)
            notes[key] = WaveFile(
                open("notes/{}/{}.wav".format(wave_type, cur_note), "rb")
            )

# main audio object
audio = AudioOut(left_channel=board.A0, right_channel=board.A1)
# mixer to allow pylyphonic playback
mixer = Mixer(
    voice_count=8,
    sample_rate=8000,
    channel_count=2,
    bits_per_sample=16,
    samples_signed=True,
)

audio.play(mixer)

# turn on the rainbow lights
for i, color in enumerate(colors):
    trellis.pixels[i, 0] = color
    trellis.pixels[i, 1] = color
    trellis.pixels[i, 2] = color

# list of keys pressed on the previous iteration
prev_pressed = []

# voice recycling variables
available_voices = [1, 2, 3, 4, 5, 6, 7]
# key to voice dictionary e.g. {... (1,2):4, (1,3):3,  ...}
used_voices = {}

# waveform selector in the last column
# default to index 0 sine
trellis.pixels[7, 0] = (255, 255, 255)
while True:
    cur_keys = trellis.pressed_keys
    # if the keys are different from previous iteration
    if cur_keys != prev_pressed:
        # loop over currently pressed keys
        for key in cur_keys:
            # if it's a note key. First 7 columns.
            if key[0] < len(note_letters):
                # if we aren't already playing this note and we have available voice
                if key not in used_voices.keys() and available_voices:
                    # build not string
                    note_for_key = "{}{}".format(note_letters[key[0]], key[1] + 3)
                    note_to_play = "{}{}".format(current_wave_type, note_for_key)
                    # if the note exists in the notes dictionary
                    if note_to_play in notes:
                        # get an available voice
                        voice_to_use = available_voices.pop()
                        used_voices[key] = voice_to_use
                        # play the note
                        mixer.play(notes[note_to_play], voice=voice_to_use, loop=True)
            else:  # last column
                current_wave_type = WAVE_TYPES[key[1]]
                # turn off all last column pixels
                for y_pixel in range(0, 4):
                    trellis.pixels[7, y_pixel] = (0, 0, 0)
                # turn on selected
                trellis.pixels[7, key[1]] = (255, 255, 255)
        if mixer.playing:
            # loop over each note that is playing
            for key in used_voices:
                # if the key is no longer down
                if key not in cur_keys:
                    # stop playing
                    mixer.stop_voice(used_voices[key])
                    # recycle voice
                    available_voices.append(used_voices[key])
                    used_voices.pop(key, None)
    # update variable for next iteration
    prev_pressed = cur_keys