The charm behind the use of the UC3637 is that it also does current limiting - good protection for motors and drivers, especially if you hit a limit stop.
Although you can do lots of stuff with computers, sometimes the use of chips that have a lot of built in protection schemes is much more efficient than to try to have the computer do everything.
Essentially, that is what Bridgeport and other machine integrators did when they used outsourced servo amp. Current monitoring, over/under voltage and other stuff was easier to do remotely and then merely send an error signal to the PC to tell that a fault had occured.
Look carefully at the use of the UC3637. It was designed to do EXACTLY what you want and requires a minimum amount of input to do so. Yes, it requires a pure analog voltage to run but there are surely step/direction to analog voltage converters that one could readily use/create to affect the interface.
In any event, the U102 application note will provide a lot of useful information to you whether you use the UC3637 to build a servo driver or not.  |