from machine import Pin, time_pulse_us
from time import sleep

trig = Pin(15, Pin.OUT)
echo = Pin(14, Pin.IN)

green_led = Pin(12, Pin.OUT)
red_led = Pin(13, Pin.OUT)

def measure_distance():
    trig.low()
    sleep(0.002)
    trig.high()
    sleep(0.01)
    trig.low()

    pulse_duration = time_pulse_us(echo, 1)
    distance_cm = (pulse_duration * 0.0343) / 2
    return distance_cm

while True:
    d = measure_distance()
    print("Distance:", d, "cm")

    if d < 100:
        red_led.on()
        green_led.off()
    else:
        green_led.on()
        red_led.off()

    sleep(0.5)