Cover-position for non smart covers

[pvoncken]

For my latest project i want to use the cover device-type to control the roof-windows of my green house.
It is a simpel motor-gearbox construction without position info.
I already have it working based on the cover example in this library.

Now i would like to add the postion to the code.
I thought that it would be possible to calculate the position based on a timer.

Could anyone help me how to integrate that timer in the code?

I already figured it out.
I start a timer in the loop triggered by the state of the output pin of the shutter.