Buffering output stream I'm looking to toggle a pin on and off in a fast and timing-sensitive manner, and I'm wondering if the Arduino Uno has any built in "buffers" that would be able to hold a set of values and send them sequentially to the output pin at high speed, separately from the rest of the loop. I could then refill the buffer with the next set to be outputted, and so on.
Is this even possible? If anyone has any documentation on what's involved, I'd really appreciate some links (or tips!) :) thanks
The closest thing to what you describe is DMA (Direct Memory Access). The Arduino doesn't have DMA. More powerful microcontrollers often do, but not little 8 bit ones.

The closest you could do is to use a timer interrupt to run a small function periodically which reads the next value from an array and sets the pin to that state.

The TimerOne or TimerThree libraries can be of help to you here.