from machine import Pin, Timer
import utime 

led = Pin(13,Pin.OUT)
start_s = Pin(15,Pin.OUT) #trigger
rec_s = Pin(14,Pin.IN,Pin.PULL_DOWN)

#function die periodisch vom Timer aufgerufen wird (interrupt timer)
#Timer Objekt anlegen
mytimer = Timer()
print("hallo")
def measure_d(mytimer):
    start_s.high()
    utime.sleep(0.000015)
    trigger.low()
    while rec_s.value() == 0:
        start_time = utime.ticks_us()
    while rec_s.value() == 1;
        stop_time = utime.ticks_us()
    duration = ticks_diff(stop_time,start_time)
    distance = (duration * 0,00343) /2
    print(duration)


mytimer.init(freq=1,mode=PERIODIC,callback=measure_d)