Reversing a small synchronous gearmotor
As far as I can make out that's the same type of motor used in a microwave oven for turntable drive. On startup they run alternate directions. The direction is not controllable. The fact that it's an AC motor with only two terminals gives us a clue that we won't be able to control direction.

I have wondered about why my microwave turntable reverses and found a good response by Sean B on The Naked Scientist:


  Most of the time they come to rest with one pole or the other nearest
  the magnet pole, attracted to it. When power is reapplied this then is
  repulsed, and as the gear set will have less friction in the reverse
  direction ( the gears will have some slack play, when running this
  makes it noisy but allows it to run freely, and when stopped it causes
  a bias) and will tend to turn into that direction with less friction.
  This then gives some momentum to the rotor and it carries on in the
  same direction.


It's the wrong motor for your task.

[Update]

Crouzet make range of reversible motors of the type you had selected. The motors have two coils - one for clockwise and one for anti-clockwise rotation. See here for pricing and link to datasheet. Speed is way too slow for your application but it may give you some ideas.







simulate this circuit &ndash; Schematic created using CircuitLab

Control circuit for reversible AC motor.

Stepper solution

Steppers are great for simple position control provided the movement doesn't stall. For your curtain application this means that the motor needs to have adequate power to guarantee successful motion. For a stepper solution you will need:


A suitable stepper motor.
A suitable gearbox or pulleys to give adequate torque at a mid-range speed for the motor.
A 'home' switch.
Stepper driver module.


Sequence will be:


On power-up drive the motor in the home direction (typically open) until the 'home' switch turns on.
When closing the curtain you run the stepper the required number of steps to just close.
When opening you can either move back the same number of steps or run the home routine again.


The stepper solution is more complex, noisier and requires additional low-voltage supply. The synchronous motor solution is simple and can be operated with a couple of switches. I'd be inclined to "keep it simple".