Calculator of cable length

The device must have:
1 . Power from the phone battery (3.7B)
2nd The indication on the OLED display is 0.96" in the form of a number of length indicator.
Three The button of the indicator.
4 . Infrared LED pair and photo resistant LTR-5576 (or analogue) for the reading of the rotating wave movement (principe as in the ball mouse).
and 5. The indicated form and dimensions
As a result, it is expected to get: a printed plate model for manufacture, the source code and a work prototype for the manufacture of the plate.
The ratio of wave rotation to the indicators on the screen is calculated by the formula.