Mr_Faineant:
It isn't failing, it works just fine, and I am able to control the speed and such, but ultimately the arduino will be doing several other tasks. Using the "on,delay, off, delay..." sequence for my STEP input is simply not IDEAL because it is subject to interrupt. I need very smooth, and very precise output, like I said, on the order of 1 ml/hour from a syringe, which is around 48 micro steps a minute (at 1/8 step). This is very slow, and seemingly easy to control, but I cannot have any pulsing. I am trying to generate a very fine spray from the tip of a needle, so, in short, I am looking for a very clean and consistent STEP input, which is why I am looking to outsource this frequency cycle to a dedicated chip.Does that make any sense, or was that a ramble?
If you haven't encountered BlinkWithoutDelay you need to, there is no need for any extra hardware, 1ms resolution should be fine for 48 steps a minute.
If you are stepping at about 1 microstep a second you will be lucky to get an even spray - the motor will jump each microstep in a tiny fraction of second and stay there till the next one - some sort of low-pass filtering would be needed in the physical domain, or gearing to allow the motor to run faster.