This module allows you play sounds from a speaker attached to the micro:bit.
audio module can be imported as
import audio or accessed via
microbit module as
In order to use the audio module you will need to provide a sound source.
A sound source is an iterable (sequence, like list or tuple, or a generator) of
frames, each of 32 samples.
audio modules plays samples at the rate of 7812.5 samples per second,
which means that it can reproduce frequencies up to 3.9kHz.
play(source, wait=True, pin=pin0, return_pin=None)¶
Play the source to completion.
- source – An iterable sound source, each element of which must be
- wait – If
True, this function will block until the source is exhausted.
- pin – Specifies which pin the speaker is connected to.
- return_pin – Specifies a differential pin to connect to the speaker instead of ground.
- source – An iterable sound source, each element of which must be an
AudioFrameobject is a list of 32 samples each of which is an unsigned byte (whole number between 0 and 255).
It takes just over 4 ms to play a single frame.
Overwrite the data in this
AudioFramewith the data from another
Parameters: other –
AudioFrameinstance from which to copy the data.
You will need a sound source, as input to the
play function. You can generate your own, like in
You don’t need to understand this section to use the
It is just here in case you wanted to know how it works.
audio module can consumes an iterable (sequence, like list or tuple, or
AudioFrame instances, each 32 samples at 7812.5 Hz, and uses
linear interpolation to output a PWM signal at 32.5 kHz, which gives tolerable
play fully copies all data from each
AudioFrame before it
next() for the next frame, so a sound source can use the same
audio module has an internal 64 sample buffer from which it reads
samples. When reading reaches the start or the mid-point of the buffer, it
triggers a callback to fetch the next
AudioFrame which is then copied into
the buffer. This means that a sound source has under 4ms to compute the next
AudioFrame, and for reliable operation needs to take less 2ms (which is
32000 cycles, so should be plenty).
from microbit import display, sleep, button_a import audio import math def repeated_frame(frame, count): for i in range(count): yield frame # Press button A to skip to next wave. def show_wave(name, frame, duration=1500): display.scroll(name + " wave", wait=False,delay=100) audio.play(repeated_frame(frame, duration),wait=False) for i in range(75): sleep(100) if button_a.is_pressed(): display.clear() audio.stop() break frame = audio.AudioFrame() for i in range(len(frame)): frame[i] = int(math.sin(math.pi*i/16)*124+128.5) show_wave("Sine", frame) triangle = audio.AudioFrame() QUARTER = len(triangle)//4 for i in range(QUARTER): triangle[i] = i*15 triangle[i+QUARTER] = 248-i*15 triangle[i+QUARTER*2] = 128-i*15 triangle[i+QUARTER*3] = i*15+8 show_wave("Triangle", triangle) square = audio.AudioFrame() HALF = len(square)//2 for i in range(HALF): square[i] = 8 square[i+HALF] = 248 show_wave("Square", square) sleep(1000) for i in range(len(frame)): frame[i] = 252-i*8 show_wave("Sawtooth", frame) del frame #Generate a waveform that goes from triangle to square wave, reasonably smoothly. frames = [ None ] * 32 for i in range(32): frames[i] = frame = audio.AudioFrame() for j in range(len(triangle)): frame[j] = (triangle[j]*(32-i) + square[j]*i)>>5 def repeated_frames(frames, count): for frame in frames: for i in range(count): yield frame display.scroll("Ascending wave", wait=False) audio.play(repeated_frames(frames, 60))