I would like to build a project whereby a motor can be turned approximately 110 degrees held there indefinitely and then returned to its original position if required.

I have an Atmel AVR328p lying around and I was hoping to use it for this, my basic thinking is to have a stepper motor controlled by a pin change interput request on one of the AVRs pins. With motor speed set by PWM with max 5V min 0V, what tye of motor would you guys suggest or any other info would be great,

 

What do you mean by "stepper" motor?

If you want to run the motor open loop (no position feedback) then a real stepper motor is the way to go. Read up on driving a stepper motor from a microcontroller. Lots of stuff about that.

If you want to use a DC gear motor, then you need position feedback, either limit switches or some sort of position sensor.

 

The stepper motor is probably the best solution, but for your case you might find that a "non-stepping motor" and limit switches (mechanical or optical) better serves your purpose.

 

A typical Stepper motor moves in 1.8° steps, so if you want it precise, you would have to gear it, you can micro-step, but the torque is greatly reduced.
Max.

 

Easy to do with a standard RC servo.