Nyan Cat, except it gets faster — RTTTL on the Raspberry Pi Pico

# Raspberry Pi Pico RTTTL example
# nyan cat, but it gets faster
# scruss - 2021-02: sorry, not sorry ...

# Uses rtttl.py from
#  github.com/dhylands/upy-rtttl
# Nyan Cat RTTTL from
#  github.com/KohaSuomi/emb-rtttl/blob/master/rtttl/nyancat.rtttl

from rtttl import RTTTL
from time import sleep_ms
from machine import Pin, PWM

b = 90    # bpm variable

# pin 26 - GP20; just the right distance from GND at pin 23
#  to use one of those PC beepers with the 4-pin headers
pwm = PWM(Pin(20))
led = Pin('LED', Pin.OUT)


def play_tone(freq, msec):
    # play RTTL notes, also flash onboard LED
    print('freq = {:6.1f} msec = {:6.1f}'.format(freq, msec))
    if freq > 0:
        pwm.freq(int(freq))       # Set frequency
        pwm.duty_u16(32767)       # 50% duty cycle
    led.on()
    sleep_ms(int(0.9 * msec))     # Play for a number of msec
    pwm.duty_u16(0)               # Stop playing for gap between notes
    led.off()
    sleep_ms(int(0.1 * msec))     # Pause for a number of msec


while True:
    nyan = 'nyancat:d=4,o=5,b=' + str(b) + ':16d#6,16e6,8f#6,8b6,16d#6,16e6,16f#6,16b6,16c#7,16d#7,16c#7,16a#6,8b6,8f#6,16d#6,16e6,8f#6,8b6,16c#7,16a#6,16b6,16c#7,16e7,16d#7,16e7,16c#7,8f#6,8g#6,16d#6,16d#6,16p,16b,16d6,16c#6,16b,16p,8b,8c#6,8d6,16d6,16c#6,16b,16c#6,16d#6,16f#6,16g#6,16d#6,16f#6,16c#6,16d#6,16b,16c#6,16b,8d#6,8f#6,16g#6,16d#6,16f#6,16c#6,16d#6,16b,16d6,16d#6,16d6,16c#6,16b,16c#6,8d6,16b,16c#6,16d#6,16f#6,16c#6,16d#6,16c#6,16b,8c#6,8b,8c#6,8f#6,8g#6,16d#6,16d#6,16p,16b,16d6,16c#6,16b,16p,8b,8c#6,8d6,16d6,16c#6,16b,16c#6,16d#6,16f#6,16g#6,16d#6,16f#6,16c#6,16d#6,16b,16c#6,16b,8d#6,8f#6,16g#6,16d#6,16f#6,16c#6,16d#6,16b,16d6,16d#6,16d6,16c#6,16b,16c#6,8d6,16b,16c#6,16d#6,16f#6,16c#6,16d#6,16c#6,16b,8c#6,8b,8c#6,8b,16f#,16g#,8b,16f#,16g#,16b,16c#6,16d#6,16b,16e6,16d#6,16e6,16f#6,8b,8b,16f#,16g#,16b,16f#,16e6,16d#6,16c#6,16b,16f#,16d#,16e,16f#,8b,16f#,16g#,8b,16f#,16g#,16b,16b,16c#6,16d#6,16b,16f#,16g#,16f#,8b,16b,16a#,16b,16f#,16g#,16b,16e6,16d#6,16e6,16f#6,8b,8a#,8b,16f#,16g#,8b,16f#,16g#,16b,16c#6,16d#6,16b,16e6,16d#6,16e6,16f#6,8b,8b,16f#,16g#,16b,16f#,16e6,16d#6,16c#6,16b,16f#,16d#,16e,16f#,8b,16f#,16g#,8b,16f#,16g#,16b,16b,16c#6,16d#6,16b,16f#,16g#,16f#,8b,16b,16a#,16b,16f#,16g#,16b,16e6,16d#6,16e6,16f#6,8b,8c#6'
    tune = RTTTL(nyan)
    print('bpm: ', b)
    for freq, msec in tune.notes():
        play_tone(freq, msec)
    b = int(b * 1.2)