Datasheet

ManualsBrandsAdafruit ManualsAdafruitCircuit Playground Express

111

112

113

114

115

116

117

118

119

120

Basic Tones

We can start by making simple tones. We will play sine waves. We first generate a single period of a sine wave in

python, with the math.sin function, and stick it into sine_wave .

Then we enable the speaker by setting the SPEAKER_ENABLE pin to be an output and True .

We can create the audio object with this line that sets the output pin and the sine wave sample object and give it the

sample array

audio = audioio.AudioOut(board.SPEAKER)

sine_wave_sample = audioio.RawSample(sine_wave)

Finally you can run audio.play() - if you only want to play the sample once, call as is. If you want it to

loop

the sample,

which we definitely do so its one long tone, pass in loop=True

You can then do whatever you like, the tone will play in the background until you call audio.stop()

Playing Audio Files

Tones are lovely but lets play some music! You can drag-and-drop audio files onto the CIRCUITPY drive and then play

them with a Python command

Here's the two files we're going to play:

https://adafru.it/zFK

import time

import array

import math

import audioio

import board

import digitalio

FREQUENCY = 440 # 440 Hz middle 'A'

SAMPLERATE = 8000 # 8000 samples/second, recommended!

# Generate one period of sine wav.

length = SAMPLERATE // FREQUENCY

sine_wave = array.array("H", [0] * length)

for i in range(length):

sine_wave[i] = int(math.sin(math.pi * 2 * i / 18) * (2 ** 15) + 2 ** 15)

# enable the speaker

speaker_enable = digitalio.DigitalInOut(board.SPEAKER_ENABLE)

speaker_enable.direction = digitalio.Direction.OUTPUT

speaker_enable.value = True

audio = audioio.AudioOut(board.A0)

sine_wave_sample = audioio.RawSample(sine_wave)

audio.play(sine_wave_sample, loop=True) # keep playing the sample over and over

time.sleep(1) # until...

audio.stop() # we tell the board to stop