from hcsr04 import HCSR04
from machine import Pin,PWM
from time import sleep
sensor=HCSR04(trigger_pin=19,echo_pin=18)
sleep(1)
i=0
led=Pin(15,Pin.OUT)
Buzzer=PWM(Pin(16))
Buzzer.freq(1700)
while True:
    distancia=sensor.distance_cm()
    print(i, ':distancia',distancia,'cm')
    i=i+1
    sleep(0.5)
    if distancia<25:
        led.on()
        sleep(0.5)
        led.off()
        sleep(distancia/1000)
        Buzzer.duty_u16(25000)
        sleep(0.5)
        Buzzer.duty_u16(0)
        sleep(distancia/1000)