import machine
from machine import Pin,PWM
from utime import sleep_us,sleep
buzzer=Pin(5,Pin.IN)
buzzer_pwm=PWM(buzzer)
echo=Pin(4,Pin.IN)
trig=Pin(2,Pin.OUT)

note = {
    'C': 250,
    'D': 300,
    'E': 350,
    'F': 400,
    'G': 450,
    'A': 500,
    'B': 550,
}
while True:
    trig.value(0)
    sleep_us(2)
    trig.value(1)
    sleep_us(10)
    trig.value(0)
    x=machine.time_pulse_us(echo,1)
    distance=(0.034*x)/2
    print('Distance:',distance, 'cm')
    if distance >= 10 and distance < 20:
        buzzer_pwm.duty(100)
        buzzer_pwm.freq(note['C'])
        sleep(0.5)
        buzzer_pwm.freq(note['E'])
        sleep(0.5)
        buzzer_pwm.freq(note['G'])
        sleep(0.5)
        buzzer_pwm.duty(0)    
    elif distance >= 20 and distance < 30:
        buzzer_pwm.duty(100)
        buzzer_pwm.freq(note['B'])
        sleep(0.5)
        buzzer_pwm.freq(note['F'])
        sleep(0.5)
        buzzer_pwm.freq(note['C'])
        sleep(0.5)
        buzzer_pwm.duty(0)
    elif distance >= 30:
        buzzer_pwm.duty(100)
        buzzer_pwm.freq(note['E'])
        sleep(0.5)
        buzzer_pwm.freq(note['G'])
        sleep(0.5)
        buzzer_pwm.freq(note['B'])
        sleep(0.5)
        buzzer_pwm.duty(0)
    else:
        buzzer_pwm.duty(0)
    sleep(2)