Play Three Tones

Welcome to Three Tones

In this lab, you will play three tones in a row. Each tone has its own pitch and its own timing. This is how simple music is made!

How It Works

Playing a sequence of tones is a simple pattern. For each tone, you:

1. Turn the sound on with duty_u16.
2. Set the pitch with freq.
3. Wait for a moment with sleep.
4. Turn the sound off with duty_u16(0).
5. Wait for a short gap before the next tone.

Lab 1: Three Tones in a Row

from machine import Pin, PWM  # import Pin and PWM classes
from utime import sleep        # import sleep to pause between notes

SPEAKER_PIN = 16               # GPIO pin connected to the speaker

# Create a PWM object on the speaker pin
speaker = PWM(Pin(SPEAKER_PIN))

# --- First tone: low pitch ---
speaker.duty_u16(1000)         # turn the sound on
speaker.freq(300)              # set pitch to 300 Hz (low note)
sleep(0.5)                     # play for half a second
speaker.duty_u16(0)            # turn the sound off
sleep(0.25)                    # short gap of silence

# --- Second tone: high pitch ---
speaker.duty_u16(1000)         # turn the sound on
speaker.freq(800)              # set pitch to 800 Hz (high note)
sleep(0.5)                     # play for half a second
speaker.duty_u16(0)            # turn the sound off
sleep(0.25)                    # short gap of silence

# --- Third tone: medium pitch ---
speaker.duty_u16(1000)         # turn the sound on
speaker.freq(400)              # set pitch to 400 Hz (medium note)
sleep(0.5)                     # play for half a second

# Always turn the sound off at the end
speaker.duty_u16(0)

What Each Line Does

1. speaker.duty_u16(1000) — turns the sound on. The value 1000 is low, making the tone quieter than 32768.
2. speaker.freq(300) — sets the pitch to 300 Hz. Lower numbers give lower pitches.
3. sleep(0.5) — waits half a second while the note plays.
4. speaker.duty_u16(0) — turns the sound off.
5. sleep(0.25) — waits a short time between notes. This gap makes each tone sound separate.

Key Idea

The gap between notes matters! Without sleep(0.25) between tones, they would blend together and sound like one long note.

Using Variables for Timing

If you want to change how long each note plays, you would have to update every sleep(0.5) line. There is a better way — store the timing values in variables:

# set the time each tone will be on
ONTIME = 0.5
# the time between the tones
OFFTIME = 0.1

Now you only need to change one number to update all the notes at once.

Lab 2: Three Tones With Variables

from machine import Pin, PWM  # import Pin and PWM classes
from utime import sleep        # import sleep to pause between notes

SPEAKER_PIN = 16               # GPIO pin connected to the speaker

# Create a PWM object on the speaker pin
speaker = PWM(Pin(SPEAKER_PIN))

ON_TIME  = 0.25                # how long each note plays (in seconds)
OFF_TIME = 0.1                 # gap of silence between notes (in seconds)

# --- Low tone ---
speaker.duty_u16(1000)         # turn the sound on
speaker.freq(300)              # low pitch: 300 Hz
sleep(ON_TIME)                 # play for ON_TIME seconds
speaker.duty_u16(0)            # turn the sound off
sleep(OFF_TIME)                # short silence

# --- High tone ---
speaker.duty_u16(1000)         # turn the sound on
speaker.freq(800)              # high pitch: 800 Hz
sleep(ON_TIME)                 # play for ON_TIME seconds
speaker.duty_u16(0)            # turn the sound off
sleep(OFF_TIME)                # short silence

# --- Medium tone ---
speaker.duty_u16(1000)         # turn the sound on
speaker.freq(400)              # medium pitch: 400 Hz
sleep(ON_TIME)                 # play for ON_TIME seconds

# Always turn the sound off at the end
speaker.duty_u16(0)

What Changed

• ON_TIME = 0.25 — one variable controls how long every note plays.
• OFF_TIME = 0.1 — one variable controls the gap between every note.
• You can now change the timing of the whole program by editing just two lines.

Monty's Tip

Using CAPITAL_LETTERS for constant values like ON_TIME is a Python convention. It tells other coders (and future you!) that this value is set once and does not change while the program runs.

Experiments

1. Change ON_TIME to a very short value like 0.05. What is the shortest note you can still hear?
2. Try changing the order of the three tones: Low → High → Medium. Then try High → Low → Medium. Which order sounds most like a "game over" sound? Which sounds most like a "level up"?
3. Add a fourth tone. Pick a frequency between 100 and 2000 Hz.

Great Work!

You just programmed your Pico to play a sequence of notes. In the next lab, you will use a loop to play a whole scale of tones automatically!