import machine
from machine import Pin,PWM
from time import sleep_us,sleep
buzzer=Pin(4,Pin.OUT)
buzzer_pwm=PWM(buzzer)
echo=Pin(18,Pin.IN)
trig=Pin(5,Pin.OUT)
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<50:
        buzzer_pwm.freq(500)
        buzzer_pwm.duty(100) 
        sleep(0.1)
        buzzer_pwm.duty(0)
        sleep(0.1)
    sleep(1)














































































#https://randomnerdtutorials.com/micropython-hc-sr04-ultrasonic-esp32-esp8266/