For my project, stepper motor will be used to rotate thermostat knob.
My problem is i want stepper motor to rotate to the shut off position of knob. When the knob is not moving(obviously it has some shutdown point), stepper motor should stop rotating.
Is there any mechanism for microcontroller to know that stepper motor is not moving anymore and shut it down?
Any ideas how can i do this?

 

For my project, stepper motor will be used to rotate thermostat knob.

For this u need a gear mechanism found in old hifi stereo systems
The Volume is driven by a motor. A clutch type mechanism in these volumes is what will work best for you

My problem is i want stepper motor to rotate to the shut off position of knob. When the knob is not moving(obviously it has some shutdown point), stepper motor should stop rotating.

To implement this you would need a limit switch to determine the shut off point.
Or let the μC decide how many steps to step the motor to shut off point.

Is there any mechanism for microcontroller to know that stepper motor is not moving anymore and shut it down?

Yup. It's called a pulse counter or detector. A IR led and sensor combination. These are readily available.

Any ideas how can i do this?

It depends on what you are trying to put this in.

Let see what other members have in mind.

 

The problem is i dont know what is the number of steps. The motor will switch off the knob and will return to same position after some time.

 

What type of unit is the thermostat connected to?
If the variable control of the thermostat is a variable resistor why not replace the control with a digital pot?
Can you post a photo of the thermostat?

 

Its a thermostat on a geyser....2 metal arms connected with motor will switch it off and on. The on position is not fixed.