Best Microstepping driver?

Hi everyone,

Do you have an idea if what is the best Microstepping driver to use for a unipolar stepper motor? I'm using atmega328 and ULN2003A and it works perfectly. My motor is rated 5V at and draws small current.

My problem is the small resolution. The resolution is 200 steps per revolution. I want to increase it to about 1600 or 2000.

Any idea?

I don't know of any commercially available unipolar microstepping drives but if you're interested in building your own, look here: http://pminmo.com/. If your motor is a 6 wire unipolar it can be wired as a bipolar by ignoring the center tap on each coil. If it is a 5 wire motor it can only be unipolar. There are a number of inexpensive bipolar microstepping drives available such as the Easy Driver from Sparkfun or the 4988 board from Pololu.