Hello,
i have motorized desk, but controller is simple - while pressing button its goes up/down.

Was wondering if its possible to upgrade it with something more sophisticated ie memory (height), or during specific interval move it up or down.
The former functionality i can achieve with simple zigbee 2ch relay - i believe... but not sure how to measure for how long relay has to be on to change the proper height.

Thank you!

 

A hall effect or proximity sensor could be used for setting a specific height required is one thought.

 

There are quite a few methods of monitoring position, with vastly different prices and accuracy levels. Measuring the height and moving to a set height would be called a closed loop servo system, it could be very accurate, and would be a good learning experience as well.
Driving up or down for a measured time would be called an open-loop system with random accuracy.
Another scheme would require an encoder to monitor the distance the drive motor has moved it up or down, and compare that with the specified move distance. That can easily be done with even a small processor.
What sort of motor does the moving? How is it reversed presently?? I ask because some motors are easier to control than others.