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Music

MicroPython on the BBC micro:bit comes with a powerful music and sound module. It's very easy to generate bleeps and bloops from the device if you attach a speaker. Use crocodile clips to attach pin 0 and GND to the positive and negative inputs on the speaker - it doesn't matter which way round they are connected to the speaker.

pin0-gnd.png

Note

Do not attempt this with a Piezo buzzer - such buzzers are only able to play a single tone.

Let's play some music:

import music

music.play(music.NYAN)

Notice that we import the music module. It contains methods used to make and control sound.

MicroPython has quite a lot of built-in melodies. Here's a complete list:

  • 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

Take the example code and change the melody. Which one is your favourite? How would you use such tunes as signals or cues?

Wolfgang Amadeus Microbit

Creating your own tunes is easy!

Each note has a name (like C# or F), an octave (telling MicroPython how high or low the note should be played) and a duration (how long it lasts through time). Octaves are indicated by a number ~ 0 is the lowest octave, 4 contains middle C and 8 is about as high as you'll ever need unless you're making music for dogs. Durations are also expressed as numbers. The higher the value of the duration the longer it will last. Such values are related to each other - for instance, a duration of 4 will last twice as long as a duration 2 (and so on). If you use the note name R then MicroPython will play a rest (i.e. silence) for the specified duration.

Each note is expressed as a string of characters like this:

NOTE[octave][:duration]

For example, "A1:4" refers to the note named A in octave number 1 to be played for a duration of 4.

Make a list of notes to create a melody (it's equivalent to creating an animation with a list of images). For example, here's how to make MicroPython play opening of "Frere Jaques":

import music

tune = ["C4:4", "D4:4", "E4:4", "C4:4", "C4:4", "D4:4", "E4:4", "C4:4",
        "E4:4", "F4:4", "G4:8", "E4:4", "F4:4", "G4:8"]
music.play(tune)

Note

MicroPython helps you to simplify such melodies. It'll remember the octave and duration values until you next change them. As a result, the example above can be re-written as:

import music

tune = ["C4:4", "D", "E", "C", "C", "D", "E", "C", "E", "F", "G:8",
        "E:4", "F", "G:8"]
music.play(tune)

Notice how the octave and duration values only change when they have to. It's a lot less typing and simpler to read.

Sound Effects

MicroPython lets you make tones that are not musical notes. For example, here's how to create a Police siren effect:

import music

while True:
    for freq in range(880, 1760, 16):
        music.pitch(freq, 6)
    for freq in range(1760, 880, -16):
        music.pitch(freq, 6)

Notice how the music.pitch method is used in this instance. It expects a frequency. For example, the frequency of 440 is the same as a concert A used to tune a symphony orchestra.

In the example above the range function is used to generate ranges of numeric values. These numbers are used to define the pitch of the tone. The three arguments for the range function are the start value, end value and step size. Therefore, the first use of range is saying, in English, "create a range of numbers between 880 and 1760 in steps of 16". The second use of range is saying, "create a range of values between 1760 and 880 in steps of -16". This is how we get a range of frequencies that go up and down in pitch like a siren.

Because the siren should last forever it's wrapped in an infinite while loop.

Importantly, we have introduced a new sort of a loop inside the while loop: the for loop. In English it's like saying, "for each item in some collection, do some activity with it". Specifically in the example above, it's saying, "for each frequency in the specified range of frequencies, play the pitch of that frequency for 6 milliseconds". Notice how the thing to do for each item in a for loop is indented (as discussed earlier) so Python knows exactly which code to run to handle the individual items.