It's operation is very simple:
1 - Rest the phone on the floor or on the object to be measured.
2 - If your phone is equipped with a cover, remove it, or set the thickness of the top and the bottom.
3 - At this point, press the start button and rotate the phone using the base as a fulcrum. Rotate the phone to cover the required distance.
4 - If the rotations are beyond the distance to be measured, correct length with your finger.
5 - If on the last rotation the phone is flipped, rotate it one more time using the board as a fulcrum, then delete a rotation using the appropriate key. In this case you can adjust the length with the finger.
The first few times check the measurements to make sure you did not move too fast. Remember that measurements made with this application are the result of an approximation. Although the measurements are precise enough, they cannot be compared to those performed with a meter.