from machine import Pin
import utime
a=300
b=0
trigger = Pin(1, Pin.OUT)
echo = Pin(2, Pin.IN)
led=Pin(3,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()
   timepassed = signalon - signaloff
   distance = (timepassed * 0.0343) / 2
   print("The distance from object is ",distance,"cm")
   if (distance<a):
    b=a-distance
    print(b)
    led.value(1)
   else:
       led.value(0)

while True:
   ultra()
   utime.sleep(1)