This is a camera controller I built for making timelapse videos. This is sometimes called an intervalometer, because it commands the camera to take a photo after some pre-set interval.
The whole thing is controlled with an Arduino Pro Mini. It can take HDR timelapses as well as normal timelapses. Also, it allows you to specify both an interval and a quantity of pictures (though this can be infinite).
More information on the project is here: trevorshp.com/creations/intervalometer.htm
(yes, I know: the number of pictures is multiplied by 10, not 100 as I say in the video.)