PIC Chopper Full Half Micro-stepping

I've been searching for some information on design considerations for chopper drives and how they work. I don't find much information about them or how to determine what the chopper frequency should be. I am interested in building a drive that is current limiting via chopping. I would also like to make it capable of full, half and microstepping. Is this getting too complicated? I have some basic ideas, but don't know the intimate details about even considering such a project. Can anyone help out with this? I'm thinking of a driver capable of supplying about 40V, 5A. I know that there are several manufacturers of stepper drives and maybe I should just bite the bullet and buy one of them instead. Any advice?

Go to this thread, read it all, you could even help by porting the translator stage to a PIC.

http://www.cnczone.com/forums/showthread.php?t=25361