from machine import Pin, PWM
beep = PWM(Pin(13), freq = 1, duty = 128)
beep.deinit()
key1 = Pin(15, Pin.IN, Pin.PULL_UP)
key2 = Pin(2, Pin.IN, Pin.PULL_UP)
key3 = Pin(4, Pin.IN, Pin.PULL_UP)
key4 = Pin(5, Pin.IN, Pin.PULL_UP)

while True:
    if key1.value() == 0:
        beep = PWM(Pin(13), freq = 294, duty = 128)
        #beep.freq(300)
    elif key2.value() == 0:
        beep = PWM(Pin(13), freq = 330, duty = 128)
    elif key3.value() == 0:
        beep = PWM(Pin(13), freq = 350, duty = 128)
    elif key4.value() == 0:
        beep = PWM(Pin(13), freq = 393, duty = 128)
    else:
        beep.deinit()