Magnetic levitation

Some students wanted to build a toothbrush holder that floated a toothbrush in mid air to avoid contamination.
I build a prototype to see if it was possible to implement the control system in software.

This project allow a small permanent magnet to be levitated by a electro magnet.
Since static passive magnetic levitation is not possible a HALL effect sensor
 is used to constantly regulate the magnetic field.
To achieve stability a software based PID controller is used.

5 potentiometers is used to control the PID parameters.
This is the Arduino code for the project