With this app you can use BlueTooth to generate and display up to 16 signals on the model railway or other corresponding signal images such as Hp0, Hp1, Hp2, Sh0, Sh1 etc.).
In addition, various other models such as the VOLLMER gantry crane can be controlled.

In this case, a direct train control is optional (by relays, for example)

The control unit is an ARDUINO μc - depending on usage a UNO or a MEGA