from time import sleep
from machine import Pin, PWM

button_A = Pin(28, Pin.IN, Pin.PULL_DOWN)
button_B = Pin(27, Pin.IN, Pin.PULL_DOWN)
led = Pin(2, Pin.OUT)

buzzer   = PWM(Pin(1))
buzzer.duty_u16(32767) # Que sea un ciclo de trabajo del 50% (32767/65535)

frequency= 1000

def ButtonIRQHandler (pin):
    global frequency
    if pin == button_A: # subir la frecuencia
        if frequency < 2000:
            frequency += 50
            led.value(1)
    elif pin == button_B: # bajar la frecuencia
        if frequency > 100:
            frequency -= 50
            led.value(0)

# Configure la IRQ y conectela al controlado
button_A.irq (trigger = machine.Pin.IRQ_RISING, handler = ButtonIRQHandler)
button_B.irq (trigger = machine.Pin.IRQ_RISING, handler = ButtonIRQHandler)
while True:
    buzzer.freq (frequency)