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Audio-Video

Wiring (Audio)​

  • Wire the AUDIO pin on the board to GP2

Part 1 - Making Sound with PWM​

PWM Basics (Quick Theory)​

  • A PWM signal flips between HIGH and LOW at a frequency (Hz).
  • We want to emulate a sine wave for a specific frequency. The highest volume will be at 50% duty cycle.

Hello, Tone!​

from machine import Pin, PWM
from time import sleep

pwm = PWM(Pin(2))

def tone(freq_hz, duty=32768):
    pwm.freq(freq_hz)
    pwm.duty_u16(duty)

def silence():
    pwm.duty_u16(0)

# Play three tones
tone(440)   # A4
sleep(0.5)
tone(523)   # C5
sleep(0.5)
tone(659)   # E5
sleep(0.5)
silence()

# When done (optional):
# pwm.deinit()

Notes helper​

NOTES = {
    "C4": 261, "D4": 294, "E4": 329, "F4": 349, "G4": 392, "A4": 440, "B4": 494,
    "C5": 523, "D5": 587, "E5": 659, "F5": 698, "G5": 784, "A5": 880, "B5": 988,
}

Melody Player (with rests)​

from machine import Pin, PWM
from time import sleep

pwm = PWM(Pin(2))
pwm.duty_u16(0)

NOTES = {"C4":261, "D4":294, "E4":329, "F4":349, "G4":392, "A4":440, "B4":494, "C5":523}

def play_note(name, duration=0.3, duty=30000):
    if name == "REST" or name is None:
        pwm.duty_u16(0)
        sleep(duration)
        return
    freq = NOTES.get(name, 0)
    if freq > 0:
        pwm.freq(freq)
        pwm.duty_u16(duty)
        sleep(duration)
        pwm.duty_u16(0)

melody = [
    ("C4", 0.25), ("D4", 0.25), ("E4", 0.25), ("REST", 0.1),
    ("E4", 0.25), ("D4", 0.25), ("C4", 0.25), ("REST", 0.2),
    ("C4", 0.25), ("G4", 0.25), ("C5", 0.35),
]

for name, dur in melody:
    play_note(name, dur)

# pwm.deinit()

Exercises - Audio​

  1. Scales Up & Down Play C major ascending and descending (C4->C5->C4), with 0.2s per note.

  2. Volume Envelope For each note, start with low duty_u16, ramp up, then ramp down.

  3. Tempo Control Add a bpm parameter and convert beats to seconds (quarter note = 60/bpm).

  4. Arpeggiator Cycle through a chord (e.g., C-E-G) at a set rate for 5 seconds.

Part 2 - Drawing on the Pico Explorer with PicoGraphics​

note

Look on the pimoroni github repo for the documentation.

Set Up the Display​

from picographics import PicoGraphics, DISPLAY_PICO_EXPLORER

display = PicoGraphics(display=DISPLAY_PICO_EXPLORER)
W, H = display.get_bounds()   # expected 240x240

Pens, Clear, Text​

from picographics import PicoGraphics, DISPLAY_PICO_EXPLORER

display = PicoGraphics(display=DISPLAY_PICO_EXPLORER)
W, H = display.get_bounds()

BLACK = display.create_pen(0, 0, 0)
WHITE = display.create_pen(255, 255, 255)
RED   = display.create_pen(255, 0, 0)

display.set_pen(BLACK)
display.clear()

display.set_pen(RED)
display.rectangle(10, 10, 100, 15)

display.set_pen(WHITE)
display.text("Hello IPW!", 10, 10, W, 2)  # (text, x, y, wrap, scale)

display.update()

Shapes & Animation Loop (basic)​

from picographics import PicoGraphics, DISPLAY_PICO_EXPLORER
from time import sleep

display = PicoGraphics(display=DISPLAY_PICO_EXPLORER)
W, H = display.get_bounds()
bg = display.create_pen(10, 10, 40)
fg = display.create_pen(240, 240, 240)
ball = display.create_pen(0, 200, 200)

x, y = 30, 30
vx, vy = 3, 2
r = 12

while True:
    display.set_pen(bg); display.clear()
    display.set_pen(fg); display.text("Bouncy!", 10, 10, W, 2)
    display.set_pen(ball); display.circle(int(x), int(y), r)
    display.update()

    x += vx; y += vy
    if x < r or x > W - r: vx = -vx
    if y < r or y > H - r: vy = -vy
    sleep(0.01)

Exercises - Display​

  1. Centered Text Write a helper draw_centered(text, y, pen, scale) that measures text using display.measure_text(...) and centers it.

  2. Progress Bar Draw a horizontal bar that fills from 0% to 100% over 3 seconds.

  3. Color Cycler Animate the background hue over time (convert HSV->RGB).

  4. Sprite Sheet (Simple) Simulate a 2-frame sprite: alternate between two rectangles (different colors) to "blink".

  5. FPS Counter Display frames per second by counting frames in 1 second windows.

Part 3 - Putting It Together: Audio-Reactive Visuals​

Visual Metronome (with Click)​

from machine import Pin, PWM
from time import ticks_ms, ticks_diff, sleep
from picographics import PicoGraphics, DISPLAY_PICO_EXPLORER

# --- Audio ---
BUZZER_PIN = 2
pwm = PWM(Pin(BUZZER_PIN))
pwm.duty_u16(0)

def click(freq=1000, dur_ms=40, duty=25000):
    pwm.freq(freq)
    pwm.duty_u16(duty)
    sleep(dur_ms/1000)
    pwm.duty_u16(0)

# --- Display ---
display = PicoGraphics(display=DISPLAY_PICO_EXPLORER)
W, H = display.get_bounds()
BLACK = display.create_pen(0,0,0)
WHITE = display.create_pen(255,255,255)
ACCENT = display.create_pen(0,200,120)

BPM = 120
beat_ms = int(60000 / BPM)
last = ticks_ms()
beat = 0

while True:
    now = ticks_ms()
    if ticks_diff(now, last) >= beat_ms:
        last = now
        beat = (beat + 1) % 4
        click(1000 if beat == 0 else 800)

    phase = ticks_diff(now, last) / beat_ms  # 0..1 within a beat
    radius = int(20 + 40 * (1 - phase))

    display.set_pen(BLACK); display.clear()
    display.set_pen(WHITE)
    display.text("METRONOME", 8, 8, W, 2)
    display.text("BPM: %d" % BPM, 8, 30, W, 2)
    display.set_pen(ACCENT)
    display.circle(W//2, H//2, radius)
    display.update()

    sleep(0.005)

Mini "Frequency Viz" (maps frequency to bar width)​

from machine import Pin, PWM
from time import sleep
from picographics import PicoGraphics, DISPLAY_PICO_EXPLORER

display = PicoGraphics(display=DISPLAY_PICO_EXPLORER)
W, H = display.get_bounds()
BG = display.create_pen(0,0,0)
BAR = display.create_pen(255,180,0)
TXT = display.create_pen(220,220,220)

BUZZER_PIN = 2
pwm = PWM(Pin(BUZZER_PIN))
pwm.duty_u16(0)

NOTES = [261, 294, 329, 349, 392, 440, 494, 523]  # C4..C5

def play_and_draw(freq, ms=300):
    pwm.freq(freq)
    pwm.duty_u16(28000)

    display.set_pen(BG); display.clear()
    display.set_pen(TXT)
    display.text("Freq: %d Hz" % freq, 10, 10, W, 2)

    # map 200..1000 Hz -> 0..W
    width = int((freq - 200) * (W / (1000 - 200)))
    width = max(0, min(W, width))

    display.set_pen(BAR)
    display.rectangle(0, H//2 - 20, width, 40)
    display.update()

    sleep(ms/1000)
    pwm.duty_u16(0)
    sleep(0.08)

while True:
    for f in NOTES:
        play_and_draw(f)

Bigger Practice Set (Mix & Match)​

  1. Piano Keys UI Draw 4 on-screen "keys" (rectangles). Highlight the active key as you play a scale. Add button inputs (A/B/X/Y).

  2. Christmas Tree++ Add music to yesterday's Christmas tree.

  3. Simon Says Flash a colored sequence (rectangles) while playing matching tones. Then wait for the user to repeat via buttons. Increase length each round.

  4. Rhythm Game Drop circles from the top at beat times; the user taps a button when they hit a target line. Score accuracy. Beep on hits.

  5. Scope-ish View Fake an oscilloscope by drawing a sine curve for the current freq. (Use math.sin to plot y = mid + amp*sin(2 * pi * f * x).)

  6. Real music! Get a MIDI file and transform it into tones using this website. Play the song!