[rcheshire (Rowland)]

Here's a working sketch. A bit clunky in places, but effective.

It will do an imaging run - dither between shots - dark frames as required (version 2 does bias and flats too - under development) -override the image limit, which is set at 40.

The first four parameters sets the intervalometer parameters. Set motor steps and delays to suit.

Dither is a bit clunky but works driving a box spiral with RA and DEC

end of session goes into a while (1) - may have to reset the board to reactivate a session in that case.

For a 5d mkii 500 milliseconds is needed to lock the mirror up and settle to fire the shutter. 100 is sufficient for a 1000D. If lock up time is too short the shutter locks up but the shutter won't activate.

Have fun.