from hcsr04 import HCSR04
from time import sleep
from machine import Pin

led1 = Pin(5, Pin.OUT)
sensor = HCSR04(trigger_pin=15, echo_pin=4)

while True:
    distance = sensor.distance_cm()
    print('Distance:', distance, 'cm')
    
    
    if distance < 20:
        led1.value(1)
        sleep(0.09)
        led1.value(0)
        sleep(0.01)
    else:
        led1.value(0)
    sleep(0.1)