example_03_chord_mixer.py

# SPDX-FileCopyrightText: 2023 John Park and @todbot / Tod Kurt
#
# SPDX-License-Identifier: MIT

import time
import board
import digitalio
import audiomixer
import synthio

# for PWM audio with an RC filter
# import audiopwmio
# audio = audiopwmio.PWMAudioOut(board.GP10)

# for I2S audio with external I2S DAC board
import audiobusio

# I2S on Audio BFF or Amp BFF on QT Py:
# audio = audiobusio.I2SOut(bit_clock=board.A3, word_select=board.A2, data=board.A1)

# I2S audio on PropMaker Feather RP2040
power = digitalio.DigitalInOut(board.EXTERNAL_POWER)
power.switch_to_output(value=True)
audio = audiobusio.I2SOut(board.I2S_BIT_CLOCK, board.I2S_WORD_SELECT, board.I2S_DATA)

mixer = audiomixer.Mixer(channel_count=1, sample_rate=22050, buffer_size=2048)
synth = synthio.Synthesizer(channel_count=1, sample_rate=22050)

audio.play(mixer)
mixer.voice[0].play(synth)
mixer.voice[0].level = 0.4

while True:
    synth.press((65, 69, 72))  # midi note 65 = F4
    time.sleep(0.5)
    synth.release((65, 69, 72))  # release the note we pressed
    time.sleep(0.5)
    mixer.voice[0].level = (mixer.voice[0].level - 0.1) % 0.4  # reduce volume each pass