from machine import Pin
from time import sleep
from hcsr04 import HCSR04
sensor = HCSR04(trigger_pin = 4, echo_pin = 13)
led1 = Pin(2, Pin.OUT)
led2 = Pin(5, Pin.OUT)
led3 = Pin(18, Pin.OUT)
while True:
    distance = sensor.distance_cm()
    print("Khoảng cách: ", distance , "cm")
    if distance < 20 :
        led1.value(1)
    elif distance < 30 :
        led1.value(1)
        led2.value(1)
    elif distance < 40 :
        led1.value(1)
        led2.value(1)
        led3.value(1)
    else :
        led1.value(0)
        led2.value(0)
        led3.value(0)