Hi Bojan. It's a positive earth - did I say negative
Anyway, the software is complete and putting the final touches to the button pushing bot. I'm using an opto coupler for the Arduino board camera interface. It's just about ready for testing.
With help from one of the guys on the Arduino forum dithering is now a square box spiral. It will need fine tuning to get the stepper speed just right.
The session time needs to be uploaded for each session, but its fairly easy to work out. In anycase it wont shut down until the board time >= session time and the last exposure complete. It won't shutdown in the middle of an image. Set and forget.
Now it needs wake-up/power up and power down. At the moment power is controlled by an external timer.
Once it's complete I'll post some images.