Thanks for the help guys. I was able to accomplish my goal using the "blink without delay example". If I have spare time I may try the countdown method but I'm wondering if the speed that the processor is able to get through the loop changes based on the task that it is working on. I will be recording the 5v output signal on two different data loggers and using it sync the two units, so it's pretty important that the signal is consistent. A few millisecs off here or there is ok but not much more.