For the past few months i've been developing a new Closed Loop stepper drive. The main problem with steppers machines is after a few years they start to jam and loose steps, usually because of dirt in linear bearings or lead screws.
My Cobra-Sv drive will work with any stepper motor fitted with either a 500 or 1000 line encoder. I recommend differential encoders, but single ended will also work for short cables. The step resolution can be jumper set to 500,1000 or 2000 steps/rev.

The drive is running a Pic Dsp with almost no other hardware other than a 393 comparator and mosfet drivers. All the PWM and chopping is done in software with timers and fast interupts. It has step/dir input and fault and error flash outputs. Also an rs232 interface for tuning . I will add a command set in the future to make it a stand alone single axis motion drive too.

Its running now and almost done, but i have a bit of noise so i have to change the pcb layout a bit or possibly go to a 4 layer board (its 2 layer now).

I am making 2 sizes , a 60volt @ 6 amp/phase drive, and a 120 volt @ 14amp/phase drive for bridgeports.
More to add soon...