7. Piezo Buzzer and music

See: https://microbit-micropython.readthedocs.io/en/v2-docs/music.html

Warning

For use of the buzzer on the breadboard, set the speaker to off so that the in-built speaker does not also play sounds.

For use of the inbuilt speaker on the V2 microbit, set the speaker to on.

7.1. Connections

The buzzer is usually connected to pin0.

If it is connected to pin1 or pin2 instead, the pin number must be used as a parameter in the play method.

7.2. Model

Place the buzzer first. It pins directly into the breadboard. Ignore the diagram suggestion that wires are used.
Connect with the jumper wires to the edge-connector using pin0 and ground, 0V.

7.3. Library

Put import music at the top under from microbit import *.

from microbit import *
import music

7.4. Volume V2

set_volume(volume)

Configure the output volume of the microbit speaker and pins.

Parameters:: volume – An integer between 0 and 255 to set the volume.

The code below increases the volume and plays a C note in octave 4 for 2 ticks at each volume.
the A-button can be pressed to exit the for-loop then the while-loop using break.
Pressing the reset button on the back of the microbit will restart the code.

from microbit import *
import music


note = "c4:2"
while True:
    for v in range(0, 255, 25):
        set_volume(v)
        music.play(note)
        if button_a.is_pressed():
            break
    if button_a.is_pressed():
        break

7.5. Speaker V2

By default sound output will be via the edge connector on pin0 and the V2 built-in speaker.

The V2 built-in speaker can be turned off or on without affecting playing via pin0.

speaker.off(): Use off() to turn off the speaker. This does not disable sound output to an edge connector pin.

speaker.on(): Use on() to turn on the speaker.

Note

The docs suggest that there is a test for the speaker status via speaker.is_on().
However, print(help(speaker)) does not list it as being available yet (as of July 2022).
See: https://microbit-micropython.readthedocs.io/en/v2-docs/microbit_micropython_api.html

For use of the buzzer on the breadboard, set the speaker to off so that the in-built speaker does not also play sounds.

music.play(music, pin=pin0, wait=True, loop=False)

Play the music.

If music can be a string, such as ‘c1:4’, or a list of notes as strings, such as [‘c’, ‘d’, ‘e’]

The duration and octave values are reset to their defaults before the music is played.

The output pin can be used to override the default pin0. Use pin=None to prevent sounds being played.

If wait is set to True, playing is blocking, and the music will be played to the end.

If loop is set to True, the music repeats until stop is called.

music.stop(pin=pin0)

Stops all music playback on the built-in speaker and any pin outputting sound.

An optional argument can be provided to specify a pin, eg. music.stop(pin1).

music.reset()

Resets the state of the following attributes as listed:

ticks = 4; bpm = 120; duration = 4; octave = 4

music.set_tempo(ticks=4, bpm=120)

Sets the tempo for playback.

A number of ticks, expressed as an integer, make a beat. The default is 4 ticks per beat.

Each beat is to be played at a certain frequency, beats per minute, expressed as an integer. The default is 120 bpm.

Examples of use:
music.set_tempo() - reset the tempo to default of ticks = 4, bpm = 120
music.set_tempo(ticks=8) - change the beat to 8 ticks
music.set_tempo(bpm=240) - just change the tempo to 240 beats per minute

The length of a beat in milliseconds is (60 sec * 1000 / bpm).

For the default value of 120 bpm, that’s 60000/120 or 1 beat in 500 milliseconds.

music.get_tempo(): Gets the current tempo as a tuple of integers: (bpm, ticks).

To display the tuple from get_tempo it can be converted to a string:

from microbit import *
import music

music.set_tempo(ticks=4, bpm=240)
tempo_data = str(music.get_tempo())
display.scroll(tempo_data)

Each value in the tuple can be accessed using its index as shown below:

from microbit import *
import music

music.set_tempo(ticks=2, bpm=120)
tempo_data = music.get_tempo()
bpm = tempo_data[0]
ticks = tempo_data[1]
display.scroll(bpm)
display.scroll(ticks)

7.6. Tuple unpacking for advanced users

For advanced users, tuple unpacking can be used instead of indices:
bpm, ticks = music.get_tempo()
See: https://www.w3schools.com/python/python_tuples_unpack.asp

from microbit import *
import music

music.set_tempo(ticks=2, bpm=120)
bpm, ticks = music.get_tempo()
display.scroll(bpm)
display.scroll(ticks)

7.7. Notes

An individual note is specified thus: NOTE[octave][:duration].
Notes are the letters a to g. Lower case or upper case are the same.
If the octave is left out it defaults to 4 (containing middle C).
If the duration is left out it defaults to 4 (a crotchet).
For example, a2:4 refers to the note “A” in octave 2 that lasts for four ticks (a tick is an arbitrary length of time defined by a tempo setting function). If the note name R is used then it is treated as a rest (silence).
Accidentals (flats and sharps) are denoted by the b (flat - a lower case b) and # (sharp - a hash symbol).
For example, Ab is A-flat and C# is C-sharp.
The octave and duration parameters are states that carry over to subsequent notes until re-specified.
The tempo can be set using music.set_tempo(ticks=4, bpm=120)

Use music.play(note) to play a note in the note variable.

from microbit import *
import music

speaker.off()
note = 'c4:8'
music.play(note)

Use music.play(notes) to play a list of notes in the notes_list variable.

The code below plays a list of notes that use various forms to specify them.

from microbit import *
import music

speaker.off()
notes_list = ['c4:1', 'e:4', 'g:8', 'c:2', 'e5', 'g4','f#','eb']

music.set_tempo(ticks=4, bpm=240)
music.play(notes_list)

Tasks

Play the 5 notes: c, e, g, e, c.
Play the 5 notes: c, e, g, e, c with a tempo of 120, 180 and 240bpm.
Design a function that takes a tempo list of 120, 240, 360 , 480 and 600 bpm as one parameter and a sleep_time with default value 1000. Use a repeat loop to set the tempo and play the notes_list.

7.8. Scales

The lists below are the notes of scales.

Press A or B to play a different scale.

from microbit import *
import music

speaker.off()
cmajor = ['c', 'd', 'e', 'f', 'g', 'a', 'b', 'c']
eminor = ['e', 'f#', 'g', 'a', 'b', 'c', 'd', 'e']

while True:
    if button_a.is_pressed():
        music.play(cmajor)
    elif button_b.is_pressed():
        music.play(eminor)
    sleep(1000)

Tasks

Play the 8 notes of D major. See: https://www.pianoscales.org/major.html
Play the 8 notes of F minor. See: https://www.pianoscales.org/minor.html
Play the D major scale when the A-button is pressed and the F minor scale when the B-button is pressed.

7.9. Built in music

There are built-in melodies that can be found by typing music.

Melodies can be played using music.play(melody).

from microbit import *
import music

speaker.off()
music.play(music.POWER_UP)

The code below uses a for-loop to loop through each melody in the melodies_list and play it.

For a list of built-in meodies see: https://microbit-micropython.readthedocs.io/en/v2-docs/music.html

from microbit import *
import music

speaker.off()
melodies_list = [music.DADADADUM, music.POWER_DOWN]
for melody in melodies_list:
    music.play(melody)

7.10. All Built in melodies

This code plays all the melodies.
the A-button can be pressed to exit the for-loop then the while-loop using break.
Pressing the reset button on the back of the microbit will restart the code.

from microbit import *
import music

speaker.off()
built_in_tunes = [music.DADADADUM, music.ENTERTAINER, music.PRELUDE,
                  music.ODE, music.NYAN, music.RINGTONE, music.FUNK, music.BLUES,
                  music.BIRTHDAY, music.WEDDING, music.FUNERAL, music.PUNCHLINE,
                  music.PYTHON, music.BADDY, music.CHASE, music.BA_DING,
                  music.WAWAWAWAA, music.JUMP_UP, music.JUMP_DOWN, music.POWER_UP,
                  music.POWER_DOWN]

while True:
    for tune in built_in_tunes:
        music.play(tune)
        sleep(1000)
        if button_a.is_pressed():
            break
    if button_a.is_pressed():
        break

Tasks

Play any 3 melodies using a list.
Use the choice function to randomly pick melodies from a melody list. See: https://www.w3schools.com/python/ref_random_choice.asp. Use https://python.microbit.org/v/3 instead of Mu editor.

7.11. Sound effects using pitch

music.pitch(frequency, duration=-1, pin=pin0, wait=True)

Plays a pitch at the integer frequency given for the duration specified in milliseconds.

Only one pitch can be played on one pin at any one time.

If duration is negative the pitch is played continuously until either the blocking call is interrupted or, in the case of a background call, a new frequency is set or stop is called.

An optional argument to specify the output pin can be used to override the default of pin0. pin=None causes no sound to play.

If wait is set to True, this function is blocking.

The code below increases the picth in steps of 16 with playing duration of 20 ms.

from microbit import *
import music

speaker.off()
for freq in range(880, 1760, 16):
    music.pitch(freq, duration=20)

Tasks

Modify the code to increase the pitch in steps of 32 with a duration of 40.
Modify the code to decrease the pitch instead.
Modify the code to increase then decrease the pitch.

7.12. Note frequencies

The table below has the frequencies for notes from A to A over 2 octaves.

The frequency of any note is doubled when going up one octave.

Note	Frequency
A	440
B flat	466
B	494
C	523
C sharp	554
D	587
D sharp	622
E	659
F	698
F sharp	740
G	784
A flat	831
A	880
B flat	932
B	988
C	1046
C sharp	1108
D	1174
D sharp	1244
E	1318
F	1396
F sharp	1480
G	1568
A flat	1662
A	1760

The code uses a for-loop to play each frequency.
the A-button can be pressed to exit the while-loop using break.
Pressing the reset button on the back of the microbit will restart the code.

from microbit import *
import music

speaker.off()
Am_freqs = [440, 494, 523, 587, 659, 698, 784, 880]
timing = 400
while True:
    for freq in Am_freqs:
        music.pitch(freq, duration=timing)
    if button_a.is_pressed():
        break

Tasks

Modify the code to play the pitches of the E minor scale. See: https://www.piano-keyboard-guide.com/e-minor-scale.html.
Modify the code to play the pitches of the D major scale. See: http://www.piano-keyboard-guide.com/d-major-scale.html.

7.13. Custom tunes

Guess the nursery rhyme (care of Raph).

from microbit import *
import music

speaker.off()
music.set_tempo(ticks=4, bpm=240)
notes_list = ['e', 'd', 'c', 'd', 'e', 'e','e','d','d','d','e','g','g','e','d','c','d','e','e','e','d','d','e','d','c']


while True:
    music.play(notes_list)
    sleep(1000)