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

sensor=HCSR04(trigger_pin=4,echo_pin=15)
led1=Pin(13,Pin.OUT)
led2=Pin(12,Pin.OUT)
led3=Pin(14,Pin.OUT)

while True:
    distance=sensor.distance_cm()
    sleep(0.1)
    if distance<20:
        led1.value(1)
        led2.value(0)
        led3.value(0)
    elif distance<30:
        led1.value(1)
        led2.value(1)
        led3.value(0)
    elif distance<40:
        led1.value(1)
        led2.value(1)
        led3.value(1)
    else:
        led1.value(0)
        led2.value(0)
        led3.value(0)