Generating Frequencies and Playing a Tune

Your board has a speaker, and a speaker plus a list of numbers is a music box. By the end of this lab, your Circuit Playground Express will play a song you picked.

Overview

You'll play a single tone on the board's built-in buzzer, then string tones together into a melody with a list and a for-loop, and finally use tuples to give each note its own duration so the tune actually sounds like the song.

Builds on: Roulette Wheel — you'll reuse the setup-then-infinite-loop program structure.

Before you start

Connect your Circuit Playground Express and open code.py on the CIRCUITPY drive. If you don't see the drive, ask for help before continuing.

You've got it when…

The buzzer plays a single tone at a frequency you chose.
Your program plays a melody from a list of notes with a for-loop.
Each note plays for its own duration, stored in a tuple with the note.

Collaboration & AI

Work: On your own. Ask a neighbor for a hand if you're stuck, but the code you submit should be yours.

AI — AIAS Level 2, AI Planning: You may search the Internet or ask an AI for the names of the notes in a melody you like. The program that plays them is yours to write. What the levels mean.

Playing a Tone

A piezo buzzer (a type of speaker) is built into the board. We'll play a tone on the buzzer.

Import the libraries we'll need.

code.py

from adafruit_circuitplayground import cp

Play a tone on the buzzer at a frequency of 440 Hz for 1 second.
```
cp.play_tone(440, 1, cp.SQUARE_WAVE)
```

Frequency is how many times a sound wave vibrates (or wiggles) every second, and it's measured in units called Hertz (Hz). When something vibrates faster (higher frequency), we hear a higher-pitched sound, like a whistle; when it vibrates more slowly (lower frequency), we hear a lower-pitched sound, like a drum.

Tip

Try this website to generate different tones and see their frequencies.

Making Music

Musical notes are just specific frequencies — for example, the note A above middle C vibrates 440 times per second (440 Hz). The frequencies can be matched to musical notes to play a tune.

Write a program that will play a song on the piezo speaker. You may search the Internet or ask an AI for the names of the notes of a melody for a song you like, then look up their frequencies in the table below.

Define some variables for the musical notes you need for your song. For example, these are the notes we would need for Twinkle, Twinkle Little Star:
```
C = 261.63
D = 293.66
E = 329.63
F = 349.23
G = 392.00
A = 440.00
```
In the setup portion of your program (before the infinite loop), create a list of the musical notes to play in order.
```
song = [C, C, G, G, A, A, G]
```

Create a for-loop to play each note.

for note in song:
    cp.play_tone(note, 0.5, cp.SQUARE_WAVE)

Note Frequency Table — open to look up your notes

Note	Frequency (Hz)
G#9/Ab9	13289.75
G9	12543.85
F#9/Gb9	11839.82
F9	11175.3
E9	10548.08
D#9/Eb9	9956.06
D9	9397.27
C#9/Db9	8869.84
C9	8372.02
B8	7902.13
A#8/Bb8	7458.62
A8	7040
G#8/Ab8	6644.88
G8	6271.93
F#8/Gb8	5919.91
F8	5587.65
E8	5274.04
D#8/Eb8	4978.03
D8	4698.64
C#8/Db8	4434.92
C8	4186.01
B7	3951.07
A#7/Bb7	3729.31
A7	3520
G#7/Ab7	3322.44
G7	3135.96
F#7/Gb7	2959.96
F7	2793.83
E7	2637.02
D#7/Eb7	2489.02
D7	2349.32
C#7/Db7	2217.46
C7	2093
B6	1975.53
A#6/Bb6	1864.66
A6	1760
G#6/Ab6	1661.22
G6	1567.98
F#6/Gb6	1479.98
F6	1396.91
E6	1318.51
D#6/Eb6	1244.51
D6	1174.66
C#6/Db6	1108.73
C6	1046.5
B5	987.77
A#5/Bb5	932.33
A5	880
G#5/Ab5	830.61
G5	783.99
F#5/Gb5	739.99
F5	698.46
E5	659.26
D#5/Eb5	622.25
D5	587.33
C#5/Db5	554.37
C5	523.25
B4	493.88
A#4/Bb4	466.16
A4 concert pitch	440
G#4/Ab4	415.3
G4	392
F#4/Gb4	369.99
F4	349.23
E4	329.63
D#4/Eb4	311.13
D4	293.66
C#4/Db4	277.18
C4 (middle C)	261.63
B3	246.94
A#3/Bb3	233.08
A3	220
G#3/Ab3	207.65
G3	196
F#3/Gb3	185
F3	174.61
E3	164.81
D#3/Eb3	155.56
D3	146.83
C#3/Db3	138.59
C3	130.81
B2	123.47
A#2/Bb2	116.54
A2	110
G#2/Ab2	103.83
G2	98
F#2/Gb2	92.5
F2	87.31
E2	82.41
D#2/Eb2	77.78
D2	73.42
C#2/Db2	69.3
C2	65.41
B1	61.74
A#1/Bb1	58.27
A1	55
G#1/Ab1	51.91
G1	49
F#1/Gb1	46.25
F1	43.65
E1	41.2
D#1/Eb1	38.89
D1	36.71
C#1/Db1	34.65
C1	32.7
B0	30.87
A#0/Bb0	29.14
A0	27.5

Tuples

That's not bad, but some notes should play longer than others. We'd like to store the duration, or how long each note should be played, with the note itself.

A Python tuple is a way to store a group of items together, like a list, but with one important difference: once you create it, you can't change it. Tuples are written using parentheses, like (1, 2, 3) or (C, D, E). They're useful when you want to keep things fixed, such as storing coordinates, RGB colors, or musical notes that shouldn't be accidentally changed in your program.

We can use a tuple to store a note and its duration like this:

(C, 0.5)

We can access the items in the tuple by assigning them to two variables like this:

note, time = (C, 0.5)
# now we can use note or time like any other variables!

We can make a list of these note/durations and loop over them to play them one at a time.

song = [(C, 0.5), (G, 0.25), (F, 0.25)]
for item in song:
    note, time = item
    cp.play_tone(note, time, cp.SQUARE_WAVE)

Challenges

Tuples for real. Update your list of notes to be a list of tuples, each storing the note and its duration.
Take a rest. Add a rest to your notes by defining a new variable named REST with the frequency set to 0.
Encore. Wrap the for-loop in an infinite loop so your song begins playing again continuously after it ends.
Light show. Using what you learned in the previous assignment, make the LED lights light up with your notes. Use a different light for each note in your song to make an effect like a finger on piano keys.

Turn It In

Submit your code.py file. You'll find it on the CIRCUITPY drive that appears when your board is connected and turned on.

The CIRCUITPY drive in a file browser with code.py selected.

How It's Graded

This lab is worth up to 4 points. One score covers everything you turn in.

Score	What it looks like
4 — Excellent	Your `code.py` plays a song a classmate could name — notes stored as named variables, the melody in a list of `(note, duration)` tuples, and one for-loop playing the whole thing with durations that make it sound like the actual song.
3 — Above Average	A melody plays from a list with a for-loop, with a minor slip — every note the same length because the tuples never made it in, or a wrong note or two in the chorus.
2 — Average	The single 440 Hz tone works but the melody is a fragment, or the song plays from copy-pasted `play_tone` lines instead of a loop over the list.
1 — Below Average	The buzzer never makes a sound, or `code.py` doesn't run.
0 — Failing	No `code.py` submitted.