from machine import Pin
from time import sleep
from hcsr04 import HCSR04
sensor = HCSR04(trigger_pin = 4, echo_pin = 15)
led1 = Pin(2, Pin.OUT)
led2 = Pin(5, Pin.OUT)
led3 = Pin(18, Pin.OUT)
while True: 
    distance = sensor.distance_cm()
    print(distance)
    sleep(0.1)
    if distance < 20:
        led1.value(1)
    elif 20 < distance < 30:
        led1.value(1)
        led2.value(1)
    elif 30 < distance < 40:
        led1.value(1)
        led2.value(1)
        led3.value(1)
    else:
        led1.value(0)
        led2.value(0)
        led3.value(0)