from machine import Pin
import utime

trigger = Pin(3,Pin.OUT)
echo = Pin(2,Pin.IN)

def ultra():
    # Pull the trigger pin low, to ensure that it is not active, then pause for two microseconds.
    trigger.low()
    utime.sleep_us(2)

    # Pull the trigger pin high for five microsends before pulling the trigger pin low
    trigger.high()
    utime.sleep_us(5)
    trigger.low()

    # Create a while loop to check the echo pin.

    while echo.value() == 0:
        # If no echo pulse is received, update a variable, signaloff so that it contains a timestamp in microseconds.
        signaloff = utime.ticks_us()
    # Create another while loop, 
    
    # this time to check if an echo has been received. This will store the current timestamp in microseconds to the signalon variable.
    while echo.value() == 1:
       signalon = utime.ticks_us()

    # timepassed, which will store the value total time taken for the pulse to leave the sensor, hit the object and return back to the sensor as an echo.
    timepassed = signalon - signaloff


    # We multiply the journey time (timepassed) by the speed of sound (343.2 m/s,
    # which is 0.0343 cm per microsecond) the product of that equation is 
    # divided by two as we do not need the total journey distance, just the distance from the object to the sensor.
    
    distance = (timepassed * 0.0343) / 2
    print("The distance from object is ",distance,"cm")





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