from machine import Pin 
import utime
#initialiser les pins
trigger = Pin(3, Pin.OUT)
echo = Pin(2, Pin.IN)
red_led=pin(18,pin.OUT)

def ultra():
    trigger.low()
    utime.sleep_us(2)

    trigger.high()
    utime.sleep_us(5)
    trigger.low()

    while echo.value() == 0:
        signaloff = utime.ticks_us()
    while echo.value() == 1:
        signalon = utime.ticks_us()
    timpassed = signalon - signaloff
    distance = (timpassed * 0.0330)/2
    print("The distance from object is:", distance,"cm")
while True:
    ultra()
    utime.sleep(1)


defmain():
    while True:
        distance=ultra()
        red_led.high()

       ***if distance < 50:
            red_led.high()
        else
            red_led.low()
        sleep(1)***