from machine import Pin,PWM,ADC
buzzer=PWM(Pin(2))
pot=ADC(Pin(26))
vot=ADC(Pin(28))
while True:
    raw=pot.read_u16()
    ra=vot.read_u16()
    buzzer.duty_u16(ra)
    freq = int(200 + (raw / 65535) * 2000)  # 200–2200 Hz
    buzzer.freq(freq)