Counting on falling and rising edge of clock

Ahh, I didn't know that. (I used to work for X, but that was before they acquired Coolrunner, so I don't know much about that family. I was pretty sure the rest didn't support that.). If that's what you're targeting, then you're probably looking at an Altera device that doesn't have a PLL in it. But if it's purely a counter, then the lowest bit is purely a reflection of the clock(or the inverse of it, depending when you start the counter). I'm guessing you need more than a counter to have rise+fall capabilities?