# PI WITH ULTRASONIC SENSOR
from machine import Pin
import utime
trigger_pin = machine.Pin(15, machine.Pin.OUT)
echo_pin = machine.Pin(14, machine.Pin.IN)

led_pin = machine.Pin(4, machine.Pin.OUT)

def measure_distance():
    trigger_pin.high()
    utime.sleep_us(10)
    trigger_pin.low()
    
    while echo_pin.value() == 0:
        pulse_start = utime.ticks_us()
    while echo_pin.value() == 1:
        pulse_end = utime.ticks_us()
    pulse_duration = pulse_start
    distance = (pulse_duration *  0.0343) / 2
    
    return distance

while True:
    distance = measure_distance()
    
    if distance < 30:
        led_pin.on()
    else:
        led_pin.off()
    utime.sleep(0.1)