Microphone V2

This object lets you access the built-in microphone available on the micro:bit V2. It can be used to respond to sound. The microphone input is located on the front of the board alongside a microphone activity LED, which is lit when the microphone is in use.

micro:bit with microphone LED on

Sound events

The microphone can respond to a pre-defined set of sound events that are based on the amplitude and wavelength of the sound.

These sound events are represented by instances of the SoundEvent class, accessible via variables in microbit.SoundEvent:

  • microbit.SoundEvent.QUIET: Represents the transition of sound events, from loud to quiet like speaking or background music.
  • microbit.SoundEvent.LOUD: Represents the transition of sound events, from quiet to loud like clapping or shouting.

Functions

microbit.microphone.current_event()
  • return: the name of the last recorded sound event, SoundEvent('loud') or SoundEvent('quiet').
microbit.microphone.was_event(event)
  • event: a sound event, such as SoundEvent.LOUD or SoundEvent.QUIET.
  • return: true if sound was heard at least once since the last call, otherwise false. was_event() also clears the sound event history before returning.
microbit.microphone.is_event(event)
  • event: a sound event, such as SoundEvent.LOUD or SoundEvent.QUIET.
  • return: true if sound event is the most recent since the last call, otherwise false. It does not clear the sound event history.
microbit.microphone.get_events()
  • return: a tuple of the event history. The most recent is listed last. get_events() also clears the sound event history before returning.
microbit.microphone.set_threshold(event, value)
  • event: a sound event, such as SoundEvent.LOUD or SoundEvent.QUIET.
  • value: The threshold level in the range 0-255. For example, set_threshold(SoundEvent.LOUD, 250) will only trigger if the sound is very loud (>= 250).
microbit.microphone.sound_level()
  • return: a representation of the sound pressure level in the range 0 to 255.

Example

An example that runs through some of the functions of the microphone API:

# Basic test for microphone.  This test should update the display when
# Button A is pressed and a loud or quiet sound *is* heard, printing the
# results. On Button B this test should update the display when a loud or
# quiet sound *was* heard, printing the results. On shake this should print
# the last sounds heard, you should try this test whilst making a loud sound
# and a quiet one before you shake.

from microbit import *

display.clear()
sound = microphone.current_event()

while True:
    if button_a.is_pressed():
        if microphone.current_event() == SoundEvent.LOUD:
            display.show(Image.SQUARE)
            uart.write('isLoud\n')
        elif microphone.current_event() == SoundEvent.QUIET:
            display.show(Image.SQUARE_SMALL)
            uart.write('isQuiet\n')
        sleep(500)
    display.clear()
    if button_b.is_pressed():
        if microphone.was_event(SoundEvent.LOUD):
            display.show(Image.SQUARE)
            uart.write('wasLoud\n')
        elif microphone.was_event(SoundEvent.QUIET):
            display.show(Image.SQUARE_SMALL)
            uart.write('wasQuiet\n')
        else:
            display.clear()
        sleep(500)
    display.clear()
    if accelerometer.was_gesture('shake'):
        sounds = microphone.get_events()
        soundLevel = microphone.sound_level()
        print(soundLevel)
        for sound in sounds:
            if sound == SoundEvent.LOUD:
                display.show(Image.SQUARE)
            elif sound == SoundEvent.QUIET:
                display.show(Image.SQUARE_SMALL)
            else:
                display.clear()
            print(sound)
            sleep(500)