Pico W fruit piano: MPR121, buzzer and RGB LED

# Fruit piano: each of the MPR121's twelve electrodes plays its own note
# on the buzzer (GP15), and the RGB LED (GP13, GP12, GP11) flashes a
# random color while it sounds.
from machine import I2C, Pin, PWM
from mpr121 import MPR121
import random
import time

NOTES = [220, 247, 262, 294, 330, 349, 392, 440, 494, 523, 587, 659]   # A3 to E5
touch = MPR121(I2C(1, sda=Pin(6), scl=Pin(7), freq=400000))
buzzer = PWM(Pin(15))
buzzer.duty_u16(0)
rgb = [PWM(Pin(n)) for n in (13, 12, 11)]
for ch in rgb:
    ch.freq(1000)

def light(r, g, b):
    for ch, v in zip(rgb, (r, g, b)):
        ch.duty_u16(v)

while True:
    pads = touch.pads()
    if pads:
        hz = NOTES[pads[0]]
        buzzer.freq(hz)
        buzzer.duty_u16(30000)
        light(random.randint(0, 65535), random.randint(0, 65535), random.randint(0, 65535))
        print("pad", pads[0], hz, "Hz")
        time.sleep_ms(500)
    buzzer.duty_u16(0)
    light(0, 0, 0)
    time.sleep_ms(20)

# mpr121.py: the MPR121 capacitive touch controller, the few registers
# a touch keyboard needs. touched() returns a 12-bit mask: electrode 0
# is bit 0.
import time

class MPR121:
    def __init__(self, i2c, addr=0x5A):
        self.i2c = i2c
        self.addr = addr
        self._set(0x80, 0x63)            # soft reset
        time.sleep_ms(1)
        self._set(0x5E, 0x00)            # stop, so the setup can be written
        for e in range(12):
            self._set(0x41 + 2 * e, 12)  # touch threshold
            self._set(0x42 + 2 * e, 6)   # release threshold
        self._set(0x5D, 0x04)            # sample timing
        self._set(0x5E, 0x8C)            # run all 12 electrodes

    def _set(self, reg, value):
        self.i2c.writeto_mem(self.addr, reg, bytes([value]))

    def touched(self):
        low, high = self.i2c.readfrom_mem(self.addr, 0x00, 2)
        return (low | high << 8) & 0x0FFF

    def pads(self):
        mask = self.touched()
        return [e for e in range(12) if mask & (1 << e)]